Improved single transistor flyback driver
Dr. Dark Current, Sat Jan 19 2008, 04:10PMThis could be interesting for the HV newbies that want to build their first flyback driver (maybe it can even be "implemented" in the Hv Wiki?)
I wanted a quick&dirty HV power supply for some lightbulb plasma experiments so I threw together the single transistor flyback driver. I played with it a bit and here's the result of my experimenting:
The 0.47uF cap should be a high-quality foil or film one. The value is not critical , my circuit starts to work well from 0.22uF.
The transistor gets warm but not as hot as with the original driver, but mainly the arcs are 3x as big and hot. The output voltage is also a bit higher.
I used an old transistor by "Tesla" (KD606), I think it should work just as well with 2N3055 or similar. (Note: a HOT or any other higher voltage transistor will not work, because they have different internal structure and the circuit will fail to oscillate)
Video here:]1200758621_152_FT0_pict0289.wmv[/file]
It is still not "fine tuned", maybe other people could try it and experiment with number of turns etc and post what works best for them?
Re: Improved single transistor flyback driver
HvHaxor05, Sat Jan 19 2008, 07:05PM
WOW i am impressed i will be sure to make this circuit and try it out my self ty
HvHaxor05, Sat Jan 19 2008, 07:05PM
WOW i am impressed i will be sure to make this circuit and try it out my self ty
Re: Improved single transistor flyback driver
Firnagzen, Sun Jan 20 2008, 01:23AM
I'll point out that since this circuit depends on the transistor being saturated to switch, the lower the saturatin voltage, the better. The MJE13007/8/9 transistors are fantastic for this.
Firnagzen, Sun Jan 20 2008, 01:23AM
I'll point out that since this circuit depends on the transistor being saturated to switch, the lower the saturatin voltage, the better. The MJE13007/8/9 transistors are fantastic for this.
Re: Improved single transistor flyback driver
MRacerxdl, Sun Jan 20 2008, 02:56AM
Very impressive arcs :D I will try some time the driver with a MJE13007 that are High Speed Transistor (up to 100Mhz if I am't mistake)
MRacerxdl, Sun Jan 20 2008, 02:56AM
Very impressive arcs :D I will try some time the driver with a MJE13007 that are High Speed Transistor (up to 100Mhz if I am't mistake)
Re: Improved single transistor flyback driver
Dr. Dark Current, Sun Jan 20 2008, 08:39AM
The MJ15003 is a nice transistor for this circuit
Dr. Dark Current, Sun Jan 20 2008, 08:39AM
Firnagzen wrote ...
I'll point out that since this circuit depends on the transistor being saturated to switch, the lower the saturatin voltage, the better. The MJE13007/8/9 transistors are fantastic for this.
I don't know if they will work, they are 400V transistors.. Something is wrong with the HV transistors, they have much higher Toff time and lower Hfe (I was trying to find out the difference and I believe it was in how the base was made - epitaxial vs. triple diffused IIRC)I'll point out that since this circuit depends on the transistor being saturated to switch, the lower the saturatin voltage, the better. The MJE13007/8/9 transistors are fantastic for this.
The MJ15003 is a nice transistor for this circuit
Re: Improved single transistor flyback driver
flannelhead, Sun Jan 20 2008, 12:52PM
It looks a bit dangerous... Isn't it too dangerous to recommend to a beginner?
However, very nice arcs from such a simple circuit!!
flannelhead, Sun Jan 20 2008, 12:52PM
It looks a bit dangerous... Isn't it too dangerous to recommend to a beginner?
However, very nice arcs from such a simple circuit!!
Re: Improved single transistor flyback driver
Zum Beispiel, Sun Jan 20 2008, 03:35PM
That is *very* impressive
I would expect to see such arcs from a halfbridge or fullbridge, but certainly not from a single transistor! I'll have to try this some time.
Zum Beispiel, Sun Jan 20 2008, 03:35PM
That is *very* impressive
I would expect to see such arcs from a halfbridge or fullbridge, but certainly not from a single transistor! I'll have to try this some time.
Re: Improved single transistor flyback driver
flannelhead, Mon Jan 21 2008, 02:08PM
I was wondering could this kind of circuit work for an sstc? Here is something similar:
Some beginners would really like it...
flannelhead, Mon Jan 21 2008, 02:08PM
I was wondering could this kind of circuit work for an sstc? Here is something similar:
Some beginners would really like it...
Re: Improved single transistor flyback driver
Dr. Dark Current, Mon Jan 21 2008, 03:24PM
Dr. Dark Current, Mon Jan 21 2008, 03:24PM
spark wrote ...
I was wondering could this kind of circuit work for an sstc? Here is something similar:
Some beginners would really like it...
I don't know, since this circuit relies on the saturation of the ferrite core... Maybe it would work but the capacitor would need to be adjusted or removed completely. For single transistor SSTC see I was wondering could this kind of circuit work for an sstc? Here is something similar:
Some beginners would really like it...
Re: Improved single transistor flyback driver
DuartmaN, Wed Jan 23 2008, 12:20PM
Amazing! i can use this HV generator to excite a tesla coil? congratulations for this forum im from portugal, and in my contry dont´t existe foruns abaut tesla coil and electronics either.
When i 14 yrs i contruct smal PVC tesla coil with a relé and a iverted 12v 200v transformer! but work´s with a smal spark´s, now i wold like to contruct a biger tesla coil but i need a HV generator, maybe contructed with a flybak T like thise on thius topic!
*sory my englis
DuartmaN, Wed Jan 23 2008, 12:20PM
Amazing! i can use this HV generator to excite a tesla coil? congratulations for this forum im from portugal, and in my contry dont´t existe foruns abaut tesla coil and electronics either.
When i 14 yrs i contruct smal PVC tesla coil with a relé and a iverted 12v 200v transformer! but work´s with a smal spark´s, now i wold like to contruct a biger tesla coil but i need a HV generator, maybe contructed with a flybak T like thise on thius topic!
*sory my englis
Re: Improved single transistor flyback driver
Marko, Wed Jan 23 2008, 12:35PM
If I had to build a blocking oscillator like that, first thing I'd do is to use a small saturable current transformer for feedback instead of saturating the power transformer's core. That should help efficiency especially with slower transistors.
Marko, Wed Jan 23 2008, 12:35PM
If I had to build a blocking oscillator like that, first thing I'd do is to use a small saturable current transformer for feedback instead of saturating the power transformer's core. That should help efficiency especially with slower transistors.
Re: Improved single transistor flyback driver
Dr. Dark Current, Wed Jan 23 2008, 04:30PM
Really this is just a "extension" of the classic STFD and it can push approx. 3 times as much power through the flyback without the transistor exploding
DuartmaN, do you mean driving the coil from the output of the flyback? If so, this would work but you need to rectify the flyback (if you already don't have a rectified one).
Dr. Dark Current, Wed Jan 23 2008, 04:30PM
Marko wrote ...
If I had to build a blocking oscillator like that, first thing I'd do is to use a small saturable current transformer for feedback instead of saturating the power transformer's core. That should help efficiency especially with slower transistors.
Marko, if I wanted to go one complexity step higher I would use a 555 driving a MOSFET If I had to build a blocking oscillator like that, first thing I'd do is to use a small saturable current transformer for feedback instead of saturating the power transformer's core. That should help efficiency especially with slower transistors.
Really this is just a "extension" of the classic STFD and it can push approx. 3 times as much power through the flyback without the transistor exploding DuartmaN, do you mean driving the coil from the output of the flyback? If so, this would work but you need to rectify the flyback (if you already don't have a rectified one).
Re: Improved single transistor flyback driver
flannelhead, Wed Jan 23 2008, 05:36PM
Can this circuit produce dangerous currents if a small FBT and 12V is used? I really wanna build this circuit but first I want to know how dangerous it is.
flannelhead, Wed Jan 23 2008, 05:36PM
Can this circuit produce dangerous currents if a small FBT and 12V is used? I really wanna build this circuit but first I want to know how dangerous it is.
Re: Improved single transistor flyback driver
Dr. Dark Current, Wed Jan 23 2008, 06:07PM
(like draw arcs to earthed wire and stay away from the HV output) I think not too dangerous currents are involved, probably below 20mA on the output.
I still need to fix the schematic, this 0.68 cap is too big, probably around 0.33 to 0.47 would be better. And to add that the flyback must use an air gap.
Dr. Dark Current, Wed Jan 23 2008, 06:07PM
spark wrote ...
Can this circuit produce dangerous currents if a small FBT and 12V is used? I really wanna build this circuit but first I want to know how dangerous it is.
No circuit is dangerous if you observe safety precautions Can this circuit produce dangerous currents if a small FBT and 12V is used? I really wanna build this circuit but first I want to know how dangerous it is.
(like draw arcs to earthed wire and stay away from the HV output) I think not too dangerous currents are involved, probably below 20mA on the output.I still need to fix the schematic, this 0.68 cap is too big, probably around 0.33 to 0.47 would be better. And to add that the flyback must use an air gap.
Re: Improved single transistor flyback driver
Littlew, Mon Apr 21 2008, 06:11PM
Wow
I'll try to made this circuit at holidays
Littlew, Mon Apr 21 2008, 06:11PM
Wow
I'll try to made this circuit at holidays
Re: Improved single transistor flyback driver
Tonic, Mon Apr 21 2008, 06:43PM
If we're back on topic, let me ask one thing - how diode and capacitor improve this circuit? I guess that capacitor bypasses spikes to supply rails, but diode? At first glance I thought that it bypasses current from primary's magnetic field to negative and helps with heating transistors, but diode is placed in way that blocks this current, so I have no clue what it does.
Tonic, Mon Apr 21 2008, 06:43PM
If we're back on topic, let me ask one thing - how diode and capacitor improve this circuit? I guess that capacitor bypasses spikes to supply rails, but diode? At first glance I thought that it bypasses current from primary's magnetic field to negative and helps with heating transistors, but diode is placed in way that blocks this current, so I have no clue what it does.
Re: Improved single transistor flyback driver
Dr. Dark Current, Mon Apr 21 2008, 07:05PM
The cap and the primary winding form a parallel resonant circuit and the driver starts to operate in "pseudo class E" mode, not exact Class E switching, but it improves performance greatly and decreases transistor heating (mainly because it has more time to turn off - Toff switching losses are minimised).
Dr. Dark Current, Mon Apr 21 2008, 07:05PM
Tonic wrote ...
If we're back on topic, let me ask one thing - how diode and capacitor improve this circuit? I guess that capacitor bypasses spikes to supply rails, but diode? At first glance I thought that it bypasses current from primary's magnetic field to negative and helps with heating transistors, but diode is placed in way that blocks this current, so I have no clue what it does.
The diode is there to extend the transistor's life - bipolar transistors don't like negative spikes on collector (I believe this is the reason why it sometimes fails in the original circuit).If we're back on topic, let me ask one thing - how diode and capacitor improve this circuit? I guess that capacitor bypasses spikes to supply rails, but diode? At first glance I thought that it bypasses current from primary's magnetic field to negative and helps with heating transistors, but diode is placed in way that blocks this current, so I have no clue what it does.
The cap and the primary winding form a parallel resonant circuit and the driver starts to operate in "pseudo class E" mode, not exact Class E switching, but it improves performance greatly and decreases transistor heating (mainly because it has more time to turn off - Toff switching losses are minimised).
Re: Improved single transistor flyback driver
Firefox, Wed Apr 23 2008, 12:41AM
I recently tried this circuit after my first few HV projects (two Tesla coils and three CW multipliers-threads to come) when a friend was getting rid of an old CRT monitor. My flyback is the crappy encased kind, but overlooking that it is rated for 26kV output with a 2A 250V input. However, being new to the hobby I didn't have any buckets of the seemingly abundant 2N3055, so I went searching through my broken computer PSU and other boards looking for a suitable replacement, and came across what I think is a real find in the Sanyo 2SC4106. While it is only rated for 7A collector current and 3A base current, the C-B rating is 500V and the C-E rating is 400V. E-B is 7V. The performance with 12V at up to 6A (computer PSU) in is reasonable with arcs starting at 1-3mm and drawing to 10-15mm, I would really like opinions on how far I can push the input with this transistor. The resistors are a chain and a bank of various 3-7 watt resistors (Req are 465 ohms and 22 ohms and are made up of 6 resistors each) so there is no worry of burning them out before anything else. Answers?
Firefox, Wed Apr 23 2008, 12:41AM
I recently tried this circuit after my first few HV projects (two Tesla coils and three CW multipliers-threads to come) when a friend was getting rid of an old CRT monitor. My flyback is the crappy encased kind, but overlooking that it is rated for 26kV output with a 2A 250V input. However, being new to the hobby I didn't have any buckets of the seemingly abundant 2N3055, so I went searching through my broken computer PSU and other boards looking for a suitable replacement, and came across what I think is a real find in the Sanyo 2SC4106. While it is only rated for 7A collector current and 3A base current, the C-B rating is 500V and the C-E rating is 400V. E-B is 7V. The performance with 12V at up to 6A (computer PSU) in is reasonable with arcs starting at 1-3mm and drawing to 10-15mm, I would really like opinions on how far I can push the input with this transistor. The resistors are a chain and a bank of various 3-7 watt resistors (Req are 465 ohms and 22 ohms and are made up of 6 resistors each) so there is no worry of burning them out before anything else. Answers?
Re: Improved single transistor flyback driver
teravolt, Wed Apr 23 2008, 01:48AM
the circuit looks like a class E tesla circuit and the 8 primary turns and .68uf cap detemins the oscillating frequency. if the biasing were changed why not use a mosfet insted if it cuold be made to oscillate
teravolt, Wed Apr 23 2008, 01:48AM
the circuit looks like a class E tesla circuit and the 8 primary turns and .68uf cap detemins the oscillating frequency. if the biasing were changed why not use a mosfet insted if it cuold be made to oscillate
Re: Improved single transistor flyback driver
Antonio, Wed Apr 23 2008, 03:05AM
This circuit does not require core saturation to work. The current in the transistor is interrupted when it leaves saturation. The oscillation frequency does not depend significantly on the capacitor, that just widens the pulse that appears at the collector when the transistor cuts the current. It can be smaller. I recommend adding another diode in series with a zener diode between emitter and base of the transistor, to avoid excessive inverse voltages there.
Antonio, Wed Apr 23 2008, 03:05AM
This circuit does not require core saturation to work. The current in the transistor is interrupted when it leaves saturation. The oscillation frequency does not depend significantly on the capacitor, that just widens the pulse that appears at the collector when the transistor cuts the current. It can be smaller. I recommend adding another diode in series with a zener diode between emitter and base of the transistor, to avoid excessive inverse voltages there.
Re: Improved single transistor flyback driver
Dr. Dark Current, Wed Apr 23 2008, 07:08AM
Firefox - for me, for some reason the higher voltage transistors (>200V) don't work very well, get hot and sometimes fail to oscillate. If it works for you, it's good. Go as high supply voltage as you dare, the transistor should theoretically stand 50V or more (watch supply current and transistor temp).
Maybe you can try reversing both primary and feedback coils, this sometimes significantly improves performance with rectified transformers.
Dr. Dark Current, Wed Apr 23 2008, 07:08AM
Antonio wrote ...
I recommend adding another diode in series with a zener diode between emitter and base of the transistor, to avoid excessive inverse voltages there.
Well, the large bipolars (e.g. 2N3055) are rated maybe an amp or more of reverse base current, so I left it out. Adding it does not hurt of course.I recommend adding another diode in series with a zener diode between emitter and base of the transistor, to avoid excessive inverse voltages there.
Firefox - for me, for some reason the higher voltage transistors (>200V) don't work very well, get hot and sometimes fail to oscillate. If it works for you, it's good. Go as high supply voltage as you dare, the transistor should theoretically stand 50V or more (watch supply current and transistor temp).
Maybe you can try reversing both primary and feedback coils, this sometimes significantly improves performance with rectified transformers.
Re: Improved single transistor flyback driver
Steve Conner, Wed Apr 23 2008, 09:48AM
Antonio, are you saying that the cycle will end when the transistor goes out of saturation, even if the core doesn't saturate?
I guess that makes sense, since the transistor out of saturation is a constant current sink, constant current implies di/dt = 0, and hence there can be no induced voltage in the transformer to provide the base drive.
Steve Conner, Wed Apr 23 2008, 09:48AM
Antonio, are you saying that the cycle will end when the transistor goes out of saturation, even if the core doesn't saturate?
I guess that makes sense, since the transistor out of saturation is a constant current sink, constant current implies di/dt = 0, and hence there can be no induced voltage in the transformer to provide the base drive.
Re: Improved single transistor flyback driver
Antonio, Wed Apr 23 2008, 03:56PM
Yes. The operation is, essentially:
1 - The collector current rises in a ramp from zero while the base current is constant.
2 - When the transistor leaves saturation, the collector current ceases to increase.
3 - The base current goes to zero because dic/dt is zero.
4 - A large positive pulse appears at the collector, caused by the current in the upper inductance charging the capacitor and the load capacitance, while a negative pulse appears at the base. The amplitude of this pulse is clipped if the be junction ruptures. Maybe good to put a diode in series with the base to prevent this, and a resistor between base and emitter to discharge the base. The zener+diode that I suggested before would just cause clipping at a smaller voltage.
5 - The pulse falls and tends to become negative, being clipped by the diode across the transistor. When the pulse returns to zero the cycle repeats.
Similar oscillators can be found in the standby power supply in the power supply of most PCs.
Antonio, Wed Apr 23 2008, 03:56PM
Dr. Spork wrote ...
Antonio, are you saying that the cycle will end when the transistor goes out of saturation, even if the core doesn't saturate?
I guess that makes sense, since the transistor out of saturation is a constant current sink, constant current implies di/dt = 0, and hence there can be no induced voltage in the transformer to provide the base drive.
Antonio, are you saying that the cycle will end when the transistor goes out of saturation, even if the core doesn't saturate?
I guess that makes sense, since the transistor out of saturation is a constant current sink, constant current implies di/dt = 0, and hence there can be no induced voltage in the transformer to provide the base drive.
Yes. The operation is, essentially:
1 - The collector current rises in a ramp from zero while the base current is constant.
2 - When the transistor leaves saturation, the collector current ceases to increase.
3 - The base current goes to zero because dic/dt is zero.
4 - A large positive pulse appears at the collector, caused by the current in the upper inductance charging the capacitor and the load capacitance, while a negative pulse appears at the base. The amplitude of this pulse is clipped if the be junction ruptures. Maybe good to put a diode in series with the base to prevent this, and a resistor between base and emitter to discharge the base. The zener+diode that I suggested before would just cause clipping at a smaller voltage.
5 - The pulse falls and tends to become negative, being clipped by the diode across the transistor. When the pulse returns to zero the cycle repeats.
Similar oscillators can be found in the standby power supply in the power supply of most PCs.
Re: Improved single transistor flyback driver
Dr. Dark Current, Wed Apr 23 2008, 04:27PM
Maybe I'm wrong but this is how I think the circuit works;
1) Transistor gets turned on by the resistor divider.
2) Voltage gets induced on the feedback coil. This voltage forces even more current through the transistor base.
3)As the transformer core saturates, the base currents starts to fall until the transistor goes out of saturation.
4) As the transistor turns off, the magnetic field collapses, and induces a high voltage pulse of OPPOSITE polarity on all coils - so this forces the base voltage to go negative, shutting the transistor off, untill the voltage "flies back" . The cycle repeats.
If the primary-feedback phasing was opposite, the circuit would fail to oscillate, because the HV spike of opposite polarity would force the transistor ON instead of OFF - so it would never happen.
EDIT - Here are quick MS Paint waveforms, in no way accurate, but they illustrate my idea good enough:
Dr. Dark Current, Wed Apr 23 2008, 04:27PM
Maybe I'm wrong but this is how I think the circuit works;
1) Transistor gets turned on by the resistor divider.
2) Voltage gets induced on the feedback coil. This voltage forces even more current through the transistor base.
3)As the transformer core saturates, the base currents starts to fall until the transistor goes out of saturation.
4) As the transistor turns off, the magnetic field collapses, and induces a high voltage pulse of OPPOSITE polarity on all coils - so this forces the base voltage to go negative, shutting the transistor off, untill the voltage "flies back" . The cycle repeats.
If the primary-feedback phasing was opposite, the circuit would fail to oscillate, because the HV spike of opposite polarity would force the transistor ON instead of OFF - so it would never happen.
EDIT - Here are quick MS Paint waveforms, in no way accurate, but they illustrate my idea good enough:
Re: Improved single transistor flyback driver
Antonio, Wed Apr 23 2008, 09:50PM
The waveforms assuming that the transformer does not saturate are similar, but the current grows linearly. I show below the result of a simulation with SwitcherCAD III, showing the voltages at the collector and at the base, and the currents trough the collector and the diode across the transistor. The simulator assumed that the be junction does not break down.
Antonio, Wed Apr 23 2008, 09:50PM
The waveforms assuming that the transformer does not saturate are similar, but the current grows linearly. I show below the result of a simulation with SwitcherCAD III, showing the voltages at the collector and at the base, and the currents trough the collector and the diode across the transistor. The simulator assumed that the be junction does not break down.
Re: Improved single transistor flyback driver
cbfull, Fri Apr 25 2008, 11:57AM
Just a quick note about that circuit, you can put a diode in series with the 22R segment to eliminate the wasted 30-40mA that drains through those two resistors. It's nothing major but if you start going up in power (which most of us do), the wasted power can become significant.
I might have to double check my archives but I have a circuit diagram with this diode included.
cbfull, Fri Apr 25 2008, 11:57AM
Just a quick note about that circuit, you can put a diode in series with the 22R segment to eliminate the wasted 30-40mA that drains through those two resistors. It's nothing major but if you start going up in power (which most of us do), the wasted power can become significant.
I might have to double check my archives but I have a circuit diagram with this diode included.
Re: Improved single transistor flyback driver
quicksilver, Fri Apr 25 2008, 02:35PM
I could be way off base here but doesn't all this have an interdependency on the flyback in question? I've used the "simple driver" with a 2N3773 and it worked a bit better than the the same driver with the MJE13009 with specific transformers.
Then the "enhanced" driver appeared to function much better with a third (NTE284) transistor. The differences between flybacks appears to be a greater variable than just the driver design alone.
This had just been my experience from my sampling....but is there validity to this???
quicksilver, Fri Apr 25 2008, 02:35PM
I could be way off base here but doesn't all this have an interdependency on the flyback in question? I've used the "simple driver" with a 2N3773 and it worked a bit better than the the same driver with the MJE13009 with specific transformers.
Then the "enhanced" driver appeared to function much better with a third (NTE284) transistor. The differences between flybacks appears to be a greater variable than just the driver design alone.
This had just been my experience from my sampling....but is there validity to this???
Re: Improved single transistor flyback driver
Proud Mary, Fri Apr 25 2008, 03:49PM
Very good points I think. TV LOPTs have been optimized not only for operation at ~16kHz, but usually to drive multiple loads from primary taps and often multiple tapped secondaries in addition to the EHT winding, and all at the same time. PC Monitor flybacks will have been optimized for operation at twice this frequency and more. I would expect this optimization to be reflected in the composition of the magnetic core, and whatever gaps it may have.
Proud Mary, Fri Apr 25 2008, 03:49PM
quicksilver wrote ...
I could be way off base here but doesn't all this have an interdependency on the flyback in question? I've used the "simple driver" with a 2N3773 and it worked a bit better than the the same driver with the MJE13009 with specific transformers.
Then the "enhanced" driver appeared to function much better with a third (NTE284) transistor. The differences between flybacks appears to be a greater variable than just the driver design alone.
This had just been my experience from my sampling....but is there validity to this???
I could be way off base here but doesn't all this have an interdependency on the flyback in question? I've used the "simple driver" with a 2N3773 and it worked a bit better than the the same driver with the MJE13009 with specific transformers.
Then the "enhanced" driver appeared to function much better with a third (NTE284) transistor. The differences between flybacks appears to be a greater variable than just the driver design alone.
This had just been my experience from my sampling....but is there validity to this???
Very good points I think. TV LOPTs have been optimized not only for operation at ~16kHz, but usually to drive multiple loads from primary taps and often multiple tapped secondaries in addition to the EHT winding, and all at the same time. PC Monitor flybacks will have been optimized for operation at twice this frequency and more. I would expect this optimization to be reflected in the composition of the magnetic core, and whatever gaps it may have.
Re: Improved single transistor flyback driver
dingo27, Fri May 02 2008, 10:37AM
i tried that schematics, but little bit different... i dont have any diode or capacitor, resistors i have 220 and 22 ohms... primary winding 5 turns and secondary 3 turns on HV transformer from CRT...
and... i am running it from 12V PC PSU
arcs are 1cm long, but not flammable (e.g. safe) and it is doing squeeking sound ( i cant WRITE exactly :) ... i am powering with it my mini SGTC ( available at teslacoils, theme TC at 12V? )
transistor should be cooled good enough, because it is slightly overheating (2n3055)
photos as soon as i get charged my batteries (8-9 hours, maybe i buy two)
dingo27, Fri May 02 2008, 10:37AM
i tried that schematics, but little bit different... i dont have any diode or capacitor, resistors i have 220 and 22 ohms... primary winding 5 turns and secondary 3 turns on HV transformer from CRT...
and... i am running it from 12V PC PSU
arcs are 1cm long, but not flammable (e.g. safe) and it is doing squeeking sound ( i cant WRITE exactly :) ... i am powering with it my mini SGTC ( available at teslacoils, theme TC at 12V? )
transistor should be cooled good enough, because it is slightly overheating (2n3055)
photos as soon as i get charged my batteries (8-9 hours, maybe i buy two)
Re: Improved single transistor flyback driver
Dr. Dark Current, Fri May 02 2008, 12:59PM
Dingo, the capacitor makes the biggest difference. Your circuit looks to me like the original schematic. With the capacitor my transistor does not run hot and I can draw out more power.
Dr. Dark Current, Fri May 02 2008, 12:59PM
Dingo, the capacitor makes the biggest difference. Your circuit looks to me like the original schematic. With the capacitor my transistor does not run hot and I can draw out more power.
Re: Improved single transistor flyback driver
Mads Barnkob, Fri May 02 2008, 04:40PM
I just tried out this circuit with components harvested from the same CRT as the flyback transformer but its not working as intended, unless I wanted something cooked.
12 V PC PSU / 14A
I used 4400uF / 25V, 500R, 27R, E13009L transistor, EGP30D diode 200V and a 0.27uF capacitor. I used 7T and 4T on the windings.
When powering it up after a few seconds the transistor is so hot that the wire on the collector will disconnect due to the heat melting the solder. Dont know if its dead, but it can repeat this torture.
Mads Barnkob, Fri May 02 2008, 04:40PM
I just tried out this circuit with components harvested from the same CRT as the flyback transformer but its not working as intended, unless I wanted something cooked.
12 V PC PSU / 14A
I used 4400uF / 25V, 500R, 27R, E13009L transistor, EGP30D diode 200V and a 0.27uF capacitor. I used 7T and 4T on the windings.
When powering it up after a few seconds the transistor is so hot that the wire on the collector will disconnect due to the heat melting the solder. Dont know if its dead, but it can repeat this torture.
Re: Improved single transistor flyback driver
Dr. Dark Current, Fri May 02 2008, 04:48PM
2) some transistor with Vce of >250V do not work well
3) maybe your transistor is cooked
Dr. Dark Current, Fri May 02 2008, 04:48PM
MadsKaizer wrote ...
I just tried out this circuit with components harvested from the same CRT as the flyback transformer but its not working as intended, unless I wanted something cooked.
12 V PC PSU / 14A
I used 4400uF / 25V, 500R, 27R, E13009L transistor, EGP30D diode 200V and a 0.27uF capacitor. I used 7T and 4T on the windings.
When powering it up after a few seconds the transistor is so hot that the wire on the collector will disconnect due to the heat melting the solder. Dont know if its dead, but it can repeat this torture.
1) try to reverse polarity of one of the windindings (feedback OR primary). If nothing happens, now reverse polarity of BOTH primary and feedback.I just tried out this circuit with components harvested from the same CRT as the flyback transformer but its not working as intended, unless I wanted something cooked.
12 V PC PSU / 14A
I used 4400uF / 25V, 500R, 27R, E13009L transistor, EGP30D diode 200V and a 0.27uF capacitor. I used 7T and 4T on the windings.
When powering it up after a few seconds the transistor is so hot that the wire on the collector will disconnect due to the heat melting the solder. Dont know if its dead, but it can repeat this torture.
2) some transistor with Vce of >250V do not work well
3) maybe your transistor is cooked
Re: Improved single transistor flyback driver
Mads Barnkob, Fri May 02 2008, 05:56PM
first try: Reversing the polarity of the feedback worked, now I can draw some arcs, but I get a shortcircuit that suddenly jumps between ABL and +40V on the flyback. Also changed to a 2n3055 which gets too hot to run for more than 30seconds.
second try: tried with old transistor again, the E13009L but once again it overheats and melts the solder.
third try: wire on chickenstick was connected to +40V instead of ABL, no more shortcircuting between those two pins and it can now draw a nice hot arc starting at 10mm and can be drawn up to about 20mm.
nice circuit and thanks for the help :)
edit: fourth try: gave it 17V and it could draw arcs about 2-4 mm further away than before, but 2n3055 heats up very fast and it can only run for a few seconds before i chicken out and turn it off.
Mads Barnkob, Fri May 02 2008, 05:56PM
Plasmaddict wrote ...
2) some transistor with Vce of >250V do not work well
3) maybe your transistor is cooked
MadsKaizer wrote ...
I just tried out this circuit with components harvested from the same CRT as the flyback transformer but its not working as intended, unless I wanted something cooked.
12 V PC PSU / 14A
I used 4400uF / 25V, 500R, 27R, E13009L transistor, EGP30D diode 200V and a 0.27uF capacitor. I used 7T and 4T on the windings.
When powering it up after a few seconds the transistor is so hot that the wire on the collector will disconnect due to the heat melting the solder. Dont know if its dead, but it can repeat this torture.
1) try to reverse polarity of one of the windindings (feedback OR primary). If nothing happens, now reverse polarity of BOTH primary and feedback.I just tried out this circuit with components harvested from the same CRT as the flyback transformer but its not working as intended, unless I wanted something cooked.
12 V PC PSU / 14A
I used 4400uF / 25V, 500R, 27R, E13009L transistor, EGP30D diode 200V and a 0.27uF capacitor. I used 7T and 4T on the windings.
When powering it up after a few seconds the transistor is so hot that the wire on the collector will disconnect due to the heat melting the solder. Dont know if its dead, but it can repeat this torture.
2) some transistor with Vce of >250V do not work well
3) maybe your transistor is cooked
first try: Reversing the polarity of the feedback worked, now I can draw some arcs, but I get a shortcircuit that suddenly jumps between ABL and +40V on the flyback. Also changed to a 2n3055 which gets too hot to run for more than 30seconds.
second try: tried with old transistor again, the E13009L but once again it overheats and melts the solder.
third try: wire on chickenstick was connected to +40V instead of ABL, no more shortcircuting between those two pins and it can now draw a nice hot arc starting at 10mm and can be drawn up to about 20mm.
nice circuit and thanks for the help :)
edit: fourth try: gave it 17V and it could draw arcs about 2-4 mm further away than before, but 2n3055 heats up very fast and it can only run for a few seconds before i chicken out and turn it off.
Re: Improved single transistor flyback driver
Dr. Dark Current, Fri May 02 2008, 06:27PM
Dr. Dark Current, Fri May 02 2008, 06:27PM
MadsKaizer wrote ...
edit: fourth try: gave it 17V and it could draw arcs about 2-4 mm further away than before, but 2n3055 heats up very fast and it can only run for a few seconds before i chicken out and turn it off.
glad you got it working, I was getting some 5cm arks and the transistor was not too hot on a big heatsink after a minute. Maybe you can try to tune it better (220-680nf high quality cap works best), and wind the windings tightly on top of each other (insulate with some tape). Do you have rectified or unrectified transformer? Do you have some gap in the core?edit: fourth try: gave it 17V and it could draw arcs about 2-4 mm further away than before, but 2n3055 heats up very fast and it can only run for a few seconds before i chicken out and turn it off.
Re: Improved single transistor flyback driver
Mads Barnkob, Fri May 02 2008, 06:59PM
Ive installed the transistor on a piece of siemens plc rail now, so it got a huge 30cm long heatsink, it can drive for minutes without even being luke warm.
Its a real messy birdnest circuit I made just to try it out, when I put it on some board ill try to tune it with different caps.
There is not much space around the core of the transformer, its a fairly new one from a computer crt, so they are wound above each other, the core aint broken if thats what you mean, else its gaps 1-1.5 mm from its housing where i have the windings placed. I guess its a rectified transformer, since its new and the output arcs are very smooth and silent compared to my ignition coil.
Mads Barnkob, Fri May 02 2008, 06:59PM
Plasmaddict wrote ...
MadsKaizer wrote ...
edit: fourth try: gave it 17V and it could draw arcs about 2-4 mm further away than before, but 2n3055 heats up very fast and it can only run for a few seconds before i chicken out and turn it off.
glad you got it working, I was getting some 5cm arks and the transistor was not too hot on a big heatsink after a minute. Maybe you can try to tune it better (220-680nf high quality cap works best), and wind the windings tightly on top of each other (insulate with some tape). Do you have rectified or unrectified transformer? Do you have some gap in the core?edit: fourth try: gave it 17V and it could draw arcs about 2-4 mm further away than before, but 2n3055 heats up very fast and it can only run for a few seconds before i chicken out and turn it off.
Ive installed the transistor on a piece of siemens plc rail now, so it got a huge 30cm long heatsink, it can drive for minutes without even being luke warm.
Its a real messy birdnest circuit I made just to try it out, when I put it on some board ill try to tune it with different caps.
There is not much space around the core of the transformer, its a fairly new one from a computer crt, so they are wound above each other, the core aint broken if thats what you mean, else its gaps 1-1.5 mm from its housing where i have the windings placed. I guess its a rectified transformer, since its new and the output arcs are very smooth and silent compared to my ignition coil.
Re: Improved single transistor flyback driver
Dr. Dark Current, Fri May 02 2008, 07:03PM
Dr. Dark Current, Fri May 02 2008, 07:03PM
MadsKaizer wrote ...
I guess its a rectified transformer, since its new and the output arcs are very smooth and silent compared to my ignition coil.
With rectified transformers try to change polarity of both primary and feedback coils, it will either work better or worse. This is because the HV output pulse is much bigger in one polarity and the diode will either block it or pass it depending on polarity.I guess its a rectified transformer, since its new and the output arcs are very smooth and silent compared to my ignition coil.
Re: Improved single transistor flyback driver
Mads Barnkob, Fri May 02 2008, 07:22PM
I will look into your surgestions tomorrow, got some other stuff that needs my attention for the rest of the day. I will write down the different settings with some pictures for comparison.
Mads Barnkob, Fri May 02 2008, 07:22PM
Plasmaddict wrote ...
MadsKaizer wrote ...
I guess its a rectified transformer, since its new and the output arcs are very smooth and silent compared to my ignition coil.
With rectified transformers try to change polarity of both primary and feedback coils, it will either work better or worse. This is because the HV output pulse is much bigger in one polarity and the diode will either block it or pass it depending on polarity.I guess its a rectified transformer, since its new and the output arcs are very smooth and silent compared to my ignition coil.
I will look into your surgestions tomorrow, got some other stuff that needs my attention for the rest of the day. I will write down the different settings with some pictures for comparison.
Re: Improved single transistor flyback driver
dingo27, Mon May 12 2008, 09:50PM
i managed to do my own HV transformer (bit nerdy... but works :) ) it gives 3-4mm sparks and one end of secondary gets really hot - red hot. i must try that with capacitor and diode, as it will be powering my yet smaller TC i am building tomorrow...
btw. i post photos as soon as i get suitable batteries, because that rechargeable i am using are crap.
but if you want to imagine, it is 15mm diameter x 2 cm width , and shape is " H " ... it works quite good for that little thing :)
dingo27, Mon May 12 2008, 09:50PM
i managed to do my own HV transformer (bit nerdy... but works :) ) it gives 3-4mm sparks and one end of secondary gets really hot - red hot. i must try that with capacitor and diode, as it will be powering my yet smaller TC i am building tomorrow...
btw. i post photos as soon as i get suitable batteries, because that rechargeable i am using are crap.
but if you want to imagine, it is 15mm diameter x 2 cm width , and shape is " H " ... it works quite good for that little thing :)
Re: Improved single transistor flyback driver
Firefox, Tue May 13 2008, 01:02AM
This is a wonderful little circuit, and I was wondering, how far could I push it with the right components? My transistor is rated 600V 7A, diode is a 250V 8A rectifier, my cap is 250VAC, my smoothing cap is 300V 600uF, and my resistors are a string and a bank of 5 5W resistors each. Could I theoretically put rectified wall voltage into it? Its already drawing ~6-8mm arcs on a 12V 6A rail of a computer PSU.
Firefox, Tue May 13 2008, 01:02AM
This is a wonderful little circuit, and I was wondering, how far could I push it with the right components? My transistor is rated 600V 7A, diode is a 250V 8A rectifier, my cap is 250VAC, my smoothing cap is 300V 600uF, and my resistors are a string and a bank of 5 5W resistors each. Could I theoretically put rectified wall voltage into it? Its already drawing ~6-8mm arcs on a 12V 6A rail of a computer PSU.
Re: Improved single transistor flyback driver
Dr. Dark Current, Tue May 13 2008, 07:08AM
For operating at higher voltages it is also advised to increase number of primary turns and possibly the value of the "upper" resistor (maybe too decrease the value of the capacitor and increase its voltage rating).
Dr. Dark Current, Tue May 13 2008, 07:08AM
Firefox wrote ...
Could I theoretically put rectified wall voltage into it? Its already drawing ~6-8mm arcs on a 12V 6A rail of a computer PSU.
No, no! The transistor voltage should be generally at least 6x your supply voltage (a rule of thumb, some transistors can take more abuse than others), so for rectified mains you would need at least 1200V transistor (if you are on 120V) or a 2000V one /if you are one 230V- I've never seen a commonly available transistor of this rating). Could I theoretically put rectified wall voltage into it? Its already drawing ~6-8mm arcs on a 12V 6A rail of a computer PSU.
For operating at higher voltages it is also advised to increase number of primary turns and possibly the value of the "upper" resistor (maybe too decrease the value of the capacitor and increase its voltage rating).
Re: Improved single transistor flyback driver
dingo27, Tue May 13 2008, 09:05AM
maybe you could use CW multiplier...
dingo27, Tue May 13 2008, 09:05AM
maybe you could use CW multiplier...
Re: Improved single transistor flyback driver
Firefox, Tue May 13 2008, 06:31PM
I could, but a CW would drop the overall output power, and I'm just trying to increase power without having to buy a new transistor. I guess I will have to find a variable power supply if I want to plug this thing in.
Firefox, Tue May 13 2008, 06:31PM
I could, but a CW would drop the overall output power, and I'm just trying to increase power without having to buy a new transistor. I guess I will have to find a variable power supply if I want to plug this thing in.
Re: Improved single transistor flyback driver
dingo27, Tue May 13 2008, 06:38PM
hm, what are you using as transistor? i built that cicuit twice, once with HV trafo from CRT screen (10-15 mm sparks) and second HV trafo by myself (4-5 mm sparks)
i was using 5 turns primary and 3 turns flyback... no capacitors etc. just transistor and 2 resistors
dingo27, Tue May 13 2008, 06:38PM
hm, what are you using as transistor? i built that cicuit twice, once with HV trafo from CRT screen (10-15 mm sparks) and second HV trafo by myself (4-5 mm sparks)
i was using 5 turns primary and 3 turns flyback... no capacitors etc. just transistor and 2 resistors
Re: Improved single transistor flyback driver
Mads Barnkob, Tue May 13 2008, 08:10PM
I just tried with a MJE13005F transistor instead of 2n3055, as I have understood from the datasheets the MJE is a faster transistor with higher voltage ratings and about the same current and on values.
but for some reason the copperlanes on my veroboard connected to the primary winding glowed up red and burned my board pretty bad.
suddenly I am not that excited to try a mosfet on it, so I better ask first, would a IRFP250 be suitable?
Mads Barnkob, Tue May 13 2008, 08:10PM
I just tried with a MJE13005F transistor instead of 2n3055, as I have understood from the datasheets the MJE is a faster transistor with higher voltage ratings and about the same current and on values.
but for some reason the copperlanes on my veroboard connected to the primary winding glowed up red and burned my board pretty bad.
suddenly I am not that excited to try a mosfet on it, so I better ask first, would a IRFP250 be suitable?
Re: Improved single transistor flyback driver
Dr. Dark Current, Tue May 13 2008, 08:24PM
To your transistor, as I said it sometimes does not work with >250V transistors because of different base structure. They usually work better with higher supply voltages and more pri. and feedback turns.
Have you tried changing polarity of one of the windings? The feedback may be of wrong polarity, so the circuit does not oscillate and your transistor is turned on all the time (shorting out the power supply).
Dr. Dark Current, Tue May 13 2008, 08:24PM
MadsKaizer wrote ...
I just tried with a MJE13005F transistor instead of 2n3055, as I have understood from the datasheets the MJE is a faster transistor with higher voltage ratings and about the same current and on values.
but for some reason the copperlanes on my veroboard connected to the primary winding glowed up red and burned my board pretty bad.
suddenly I am not that excited to try a mosfet on it, so I better ask first, would a IRFP250 be suitable?
This circuit will not work with MOSFETs as they have totally different gate drive requiremens.I just tried with a MJE13005F transistor instead of 2n3055, as I have understood from the datasheets the MJE is a faster transistor with higher voltage ratings and about the same current and on values.
but for some reason the copperlanes on my veroboard connected to the primary winding glowed up red and burned my board pretty bad.
suddenly I am not that excited to try a mosfet on it, so I better ask first, would a IRFP250 be suitable?
To your transistor, as I said it sometimes does not work with >250V transistors because of different base structure. They usually work better with higher supply voltages and more pri. and feedback turns.
Have you tried changing polarity of one of the windings? The feedback may be of wrong polarity, so the circuit does not oscillate and your transistor is turned on all the time (shorting out the power supply).
Re: Improved single transistor flyback driver
Mads Barnkob, Tue May 13 2008, 08:32PM
I reinstalled the 2n3055 to test the circuit and luckily its still working despite it looks like bombs were droppped.
you think that changeging polarity would work even though both transistors share pinout and are connected in the same way.
offtopic: a friend of mine raised a question about the resonance of the flyback would interfer with a tesla coils resonance if the flyback is used as the powersupply, say flyback runs at 15-50 khz vs tc at 400-800khz?
Mads Barnkob, Tue May 13 2008, 08:32PM
Dr. Monster Arc wrote ...
To your transistor, as I said it sometimes does not work with >250V transistors because of different base structure. They usually work better with higher supply voltages and more pri. and feedback turns.
Have you tried changing polarity of one of the windings? The feedback may be of wrong polarity, so the circuit does not oscillate and your transistor is turned on all the time (shorting out the power supply).
MadsKaizer wrote ...
I just tried with a MJE13005F transistor instead of 2n3055, as I have understood from the datasheets the MJE is a faster transistor with higher voltage ratings and about the same current and on values.
but for some reason the copperlanes on my veroboard connected to the primary winding glowed up red and burned my board pretty bad.
suddenly I am not that excited to try a mosfet on it, so I better ask first, would a IRFP250 be suitable?
This circuit will not work with MOSFETs as they have totally different gate drive requiremens.I just tried with a MJE13005F transistor instead of 2n3055, as I have understood from the datasheets the MJE is a faster transistor with higher voltage ratings and about the same current and on values.
but for some reason the copperlanes on my veroboard connected to the primary winding glowed up red and burned my board pretty bad.
suddenly I am not that excited to try a mosfet on it, so I better ask first, would a IRFP250 be suitable?
To your transistor, as I said it sometimes does not work with >250V transistors because of different base structure. They usually work better with higher supply voltages and more pri. and feedback turns.
Have you tried changing polarity of one of the windings? The feedback may be of wrong polarity, so the circuit does not oscillate and your transistor is turned on all the time (shorting out the power supply).
I reinstalled the 2n3055 to test the circuit and luckily its still working despite it looks like bombs were droppped.
you think that changeging polarity would work even though both transistors share pinout and are connected in the same way.
offtopic: a friend of mine raised a question about the resonance of the flyback would interfer with a tesla coils resonance if the flyback is used as the powersupply, say flyback runs at 15-50 khz vs tc at 400-800khz?
Re: Improved single transistor flyback driver
Dr. Dark Current, Tue May 13 2008, 08:45PM
Dr. Dark Current, Tue May 13 2008, 08:45PM
MadsKaizer wrote ...
you think that changeging polarity would work even though both transistors share pinout and are connected in the same way.
In this case it won't work, like you say. The transistor is probably not good for the job you think that changeging polarity would work even though both transistors share pinout and are connected in the same way.
Re: Improved single transistor flyback driver
Firefox, Tue May 13 2008, 08:56PM
My transistor is a Sanyo 2SC4106 (400V 7A) salvaged from a PC PSU that I blew out. There were two of them, and ironically I think it was this chip's twin that fried. Screwed to the heatsink it came on with lots of thermal paste, this transistor only gets hot after about 5 minutes of operation. Arcs start at about 3-5mm and can be drawn to about 12-14mm. Toying with the values of the resistors seemed to help/hurt the arc length a bit, but I don't have any brand-new parts, so both resistors are made from several 2-4W resistors soldiered together. This is all with a 4 turn primary, and a 2 turn feedback.
Firefox, Tue May 13 2008, 08:56PM
My transistor is a Sanyo 2SC4106 (400V 7A) salvaged from a PC PSU that I blew out. There were two of them, and ironically I think it was this chip's twin that fried. Screwed to the heatsink it came on with lots of thermal paste, this transistor only gets hot after about 5 minutes of operation. Arcs start at about 3-5mm and can be drawn to about 12-14mm. Toying with the values of the resistors seemed to help/hurt the arc length a bit, but I don't have any brand-new parts, so both resistors are made from several 2-4W resistors soldiered together. This is all with a 4 turn primary, and a 2 turn feedback.
Re: Improved single transistor flyback driver
Mads Barnkob, Tue May 13 2008, 09:11PM
Firefox, have you tried 8 turn primary / 4 turn feedback?
that setting worked out best for my flyback after trying alot of different settings. I can start arcs 15mm.
Mads Barnkob, Tue May 13 2008, 09:11PM
Firefox, have you tried 8 turn primary / 4 turn feedback?
that setting worked out best for my flyback after trying alot of different settings. I can start arcs 15mm.
Re: Improved single transistor flyback driver
dingo27, Tue May 13 2008, 09:42PM
i am running one TC with that... nothing happened, it is normal (an SGTC )
second is to come
dingo27, Tue May 13 2008, 09:42PM
MadsKaizer wrote ...
offtopic: a friend of mine raised a question about the resonance of the flyback would interfer with a tesla coils resonance if the flyback is used as the powersupply, say flyback runs at 15-50 khz vs tc at 400-800khz?
offtopic: a friend of mine raised a question about the resonance of the flyback would interfer with a tesla coils resonance if the flyback is used as the powersupply, say flyback runs at 15-50 khz vs tc at 400-800khz?
i am running one TC with that... nothing happened, it is normal (an SGTC )
second is to come
Re: Improved single transistor flyback driver
Antonio, Wed May 14 2008, 01:04AM
About high-voltage transistors, in all the monitors that I have seen the flyback is driven by a transistor rated at 1500 V, several A. Just find the transistor connected to the flyback primary winding where you found the flyback. Take also the diode also rated at 1500 V that is in parallel with it, and the high voltage capacitor (several nF, 1600 V) that is usually there too.
Antonio, Wed May 14 2008, 01:04AM
About high-voltage transistors, in all the monitors that I have seen the flyback is driven by a transistor rated at 1500 V, several A. Just find the transistor connected to the flyback primary winding where you found the flyback. Take also the diode also rated at 1500 V that is in parallel with it, and the high voltage capacitor (several nF, 1600 V) that is usually there too.
Re: Improved single transistor flyback driver
quicksilver, Wed May 14 2008, 03:12PM
I could be wrong about this but the transistor that you are taking about IS rated at 1500v but at the low current (ma) level level. I was looking up a great many transistors on my day off and I am very well acquainted with ripping guts from old stuff and re-using it. Unfortunately the transistor (equivalent to a C4634) is a 1500v but low current according to data sheet. You may have gotten lucky; but I'd check again because the high voltage/low current part is common.
However if you have a monitor that you want to use for parts there is a large fellow that's 400v / 12A & it's the C4423. There are also a few MJE13005, MJE13007 & 9's available. Those fellows are common.
I'm of the opinion that there are so many vast differences in flybacks & their construction that not one transistor or methodology is the answer. However I've found some commonalities..... If you use well made, evenly spaced coils (even and well constructed) with a thicker well insulated wire, you may have better arcs. The idea of an 8/4 winding is what I have had success with also. BUT, I've also had fantastic success with a weird 10/3 winding that if I changed it....but fall to sh*t....
The best transistor for a variety of transformers that I have personally used (over a broad spectrum of flybacks) is the 2N3773. Best performance over a broader range.....I have ripped apart a very large amount of stuff; for a really large selection of parts. Another great source for power transistors are larger, broken amplifiers for home stereos, musical instruments, etc.
I get a monitor (or TV or MO - whatever) and really pull every part off that bastard. Using the traces and looking closely at the circuit board helps a lot in understanding a great many things! THEN finding out what I've got in the way of transistors becomes a real challenge. Because a transistor MAY be used for horizontal diffusion in a TV (let's say) but it could still be used in HV applications....IF you check the specs and don't simply make a generalization based on superficialities.
It's been a good learning process for me. The parts are there! There are very few things that need to be bought. But I am beginning to see th value in a big breadboard.
quicksilver, Wed May 14 2008, 03:12PM
I could be wrong about this but the transistor that you are taking about IS rated at 1500v but at the low current (ma) level level. I was looking up a great many transistors on my day off and I am very well acquainted with ripping guts from old stuff and re-using it. Unfortunately the transistor (equivalent to a C4634) is a 1500v but low current according to data sheet. You may have gotten lucky; but I'd check again because the high voltage/low current part is common.
However if you have a monitor that you want to use for parts there is a large fellow that's 400v / 12A & it's the C4423. There are also a few MJE13005, MJE13007 & 9's available. Those fellows are common.
I'm of the opinion that there are so many vast differences in flybacks & their construction that not one transistor or methodology is the answer. However I've found some commonalities..... If you use well made, evenly spaced coils (even and well constructed) with a thicker well insulated wire, you may have better arcs. The idea of an 8/4 winding is what I have had success with also. BUT, I've also had fantastic success with a weird 10/3 winding that if I changed it....but fall to sh*t....
The best transistor for a variety of transformers that I have personally used (over a broad spectrum of flybacks) is the 2N3773. Best performance over a broader range.....I have ripped apart a very large amount of stuff; for a really large selection of parts. Another great source for power transistors are larger, broken amplifiers for home stereos, musical instruments, etc.
I get a monitor (or TV or MO - whatever) and really pull every part off that bastard. Using the traces and looking closely at the circuit board helps a lot in understanding a great many things! THEN finding out what I've got in the way of transistors becomes a real challenge. Because a transistor MAY be used for horizontal diffusion in a TV (let's say) but it could still be used in HV applications....IF you check the specs and don't simply make a generalization based on superficialities.
It's been a good learning process for me. The parts are there! There are very few things that need to be bought. But I am beginning to see th value in a big breadboard.
Re: Improved single transistor flyback driver
dingo27, Wed May 14 2008, 03:59PM
that diode you are talking about is BY329 series as i writed few posts sooner. Usually looks like TO220 but only with 2 legs...
that diode is perfect for most applications
dingo27, Wed May 14 2008, 03:59PM
that diode you are talking about is BY329 series as i writed few posts sooner. Usually looks like TO220 but only with 2 legs...
that diode is perfect for most applications
Re: Improved single transistor flyback driver
Mads Barnkob, Wed May 14 2008, 05:23PM
Another thought on optimization.
I used 0,75 mm^2 (awg 18-19) pvc insulated wire to wind primary and feedback, would it be better to use heavy enamaled magnet wire?
I have now written about my version of it and pictures can be seen at http://kaizerpowerelectronics.dk/high-voltage/2n3055-flyback-driver/
for now its in danish till I have time to translate it, but there is still pictures to enjoy
Mads Barnkob, Wed May 14 2008, 05:23PM
Another thought on optimization.
I used 0,75 mm^2 (awg 18-19) pvc insulated wire to wind primary and feedback, would it be better to use heavy enamaled magnet wire?
I have now written about my version of it and pictures can be seen at http://kaizerpowerelectronics.dk/high-voltage/2n3055-flyback-driver/
for now its in danish till I have time to translate it, but there is still pictures to enjoy
Re: Improved single transistor flyback driver
Antonio, Thu May 15 2008, 12:09AM
This is the biggest flyback driver transistor that I have, found in a monitor:
Another, less powerful, but easier to find. It has many equivalents:
Transistors are really limited to low currents, if they are sustaining high voltage at the same time and for long periods. Power dissipation limits this. But in these flyback drivers they operate ideally as switches, with high current at low voltage or no current at high voltage, and only at switching instants there is significant power dissipation.
Another useful component that you can find in monitors are switching power supply controllers. Some are very simple to use, and are more flexible that the 555s that people is using to control the drivers. An example:
Antonio, Thu May 15 2008, 12:09AM
This is the biggest flyback driver transistor that I have, found in a monitor:
Another, less powerful, but easier to find. It has many equivalents:
Transistors are really limited to low currents, if they are sustaining high voltage at the same time and for long periods. Power dissipation limits this. But in these flyback drivers they operate ideally as switches, with high current at low voltage or no current at high voltage, and only at switching instants there is significant power dissipation.
Another useful component that you can find in monitors are switching power supply controllers. Some are very simple to use, and are more flexible that the 555s that people is using to control the drivers. An example:
Re: Improved single transistor flyback driver
quicksilver, Thu May 15 2008, 05:11AM
@MadsKaizer: I've had VERY good responses w/ the insulated 18. In fact, that's all I use now. I can honestly tell a difference between that and the enameled thinner magnet material. But what I've found very important is that simply by the insulation, my coils are tighter and even and that may be a serious issue (IMO). In addition, if the core has sharp corners, it can shave off the enamel.
@ Antonio: Posting what you have found is a GREAT help. The basic problem is that often (depending upon the year of manufacture and maker) the nomenclature (naming conventions) can differ. But generally a Cxxxx is common enough to get most folks close. Good stuff!
quicksilver, Thu May 15 2008, 05:11AM
@MadsKaizer: I've had VERY good responses w/ the insulated 18. In fact, that's all I use now. I can honestly tell a difference between that and the enameled thinner magnet material. But what I've found very important is that simply by the insulation, my coils are tighter and even and that may be a serious issue (IMO). In addition, if the core has sharp corners, it can shave off the enamel.
@ Antonio: Posting what you have found is a GREAT help. The basic problem is that often (depending upon the year of manufacture and maker) the nomenclature (naming conventions) can differ. But generally a Cxxxx is common enough to get most folks close. Good stuff!
Re: Improved single transistor flyback driver
dingo27, Fri May 16 2008, 07:35PM
whoah, i tried thet schematics with diode and cap. and what i found is, that when i use that, i blow every 2n3055 in it. I blowed 2 and don't want to blow another... What capacitance i should use?
aaah... i was really angry for that, i trashed circuit board to wall...
it was working once, few seconds...
dingo27, Fri May 16 2008, 07:35PM
whoah, i tried thet schematics with diode and cap. and what i found is, that when i use that, i blow every 2n3055 in it. I blowed 2 and don't want to blow another... What capacitance i should use?
aaah... i was really angry for that, i trashed circuit board to wall...
it was working once, few seconds...
Re: Improved single transistor flyback driver
Dr. Dark Current, Fri May 16 2008, 07:44PM
-try to start with lower voltages and if nothing happens, reverse polarity of one of the coils.
Dr. Dark Current, Fri May 16 2008, 07:44PM
dingo27 wrote ...
whoah, i tried thet schematics with diode and cap. and what i found is, that when i use that, i blow every 2n3055 in it. I blowed 2 and don't want to blow another... What capacitance i should use?
aaah... i was really angry for that, i trashed circuit board to wall...
it was working once, few seconds...
If you mean the resonant capacitor, it should be between 200nF to 500nF (approx.) and it MUST be non-polarised film or foil type, (PP/MKP type preferred).whoah, i tried thet schematics with diode and cap. and what i found is, that when i use that, i blow every 2n3055 in it. I blowed 2 and don't want to blow another... What capacitance i should use?
aaah... i was really angry for that, i trashed circuit board to wall...
it was working once, few seconds...
-try to start with lower voltages and if nothing happens, reverse polarity of one of the coils.
Re: Improved single transistor flyback driver
dingo27, Sat May 17 2008, 09:18AM
it worked, it worked... i used 0.47uF (470n, right?) foil from power supply clearing circuit...
but nothing with it was working as without it. Maybe i am using BAD transistor, because first manufacturer was (i dunno name, some stupid logo i newer saw yet... maybe china stuff), but as i am using ones with ISC on it, i burn them as with ot without C and D.
Dont buy 2n3055 with ISC on it! next time i will request another manufacturer from local radio shack.
dingo27, Sat May 17 2008, 09:18AM
it worked, it worked... i used 0.47uF (470n, right?) foil from power supply clearing circuit...
but nothing with it was working as without it. Maybe i am using BAD transistor, because first manufacturer was (i dunno name, some stupid logo i newer saw yet... maybe china stuff), but as i am using ones with ISC on it, i burn them as with ot without C and D.
Dont buy 2n3055 with ISC on it! next time i will request another manufacturer from local radio shack.
Re: Improved single transistor flyback driver
Berni, Sat May 17 2008, 10:23AM
I once got my hands on some fake 2N3055.
They could handle as much power as a signal transistor.Then i grinded it open and saw a tiny die in there that was coverd in some white stuff.These fake trasistor had its partnumber printed on it in red, then found out all these red 2N3055 are fake
Berni, Sat May 17 2008, 10:23AM
I once got my hands on some fake 2N3055.
They could handle as much power as a signal transistor.Then i grinded it open and saw a tiny die in there that was coverd in some white stuff.These fake trasistor had its partnumber printed on it in red, then found out all these red 2N3055 are fake
Re: Improved single transistor flyback driver
Mads Barnkob, Sun May 18 2008, 02:58PM
I have used a capacitor as low as 10nF and it made it behave well crazy, very flickering streamers that screamed.
you should be able to drive it without diode, i did that while experimenting.
Mads Barnkob, Sun May 18 2008, 02:58PM
I have used a capacitor as low as 10nF and it made it behave well crazy, very flickering streamers that screamed.
you should be able to drive it without diode, i did that while experimenting.
Re: Improved single transistor flyback driver
dingo27, Sun May 18 2008, 06:05PM
one question - can anybody push the upper "cylinder" on 2n3055 ??? because i can and i think that was impossible with other TO3 transistors...
i can push it downward maybe 2-3 mm ...
with su169 i was cooling it that on upper cylinder was a iron strip and pushing it more to cooler, and it was never any sign of pushing on transistor when i removed it.
//i know that heatsink is on bottom, i was just using bar so transisor could be strongly mounted to cooler
dingo27, Sun May 18 2008, 06:05PM
one question - can anybody push the upper "cylinder" on 2n3055 ??? because i can and i think that was impossible with other TO3 transistors...
i can push it downward maybe 2-3 mm ...
with su169 i was cooling it that on upper cylinder was a iron strip and pushing it more to cooler, and it was never any sign of pushing on transistor when i removed it.
//i know that heatsink is on bottom, i was just using bar so transisor could be strongly mounted to cooler
Re: Improved single transistor flyback driver
Berni, Sun May 18 2008, 07:04PM
I never had such a case. But there are a lot of fake 2N3055s out there that have a red partnumber on it, those are fake. It should be black
Berni, Sun May 18 2008, 07:04PM
I never had such a case. But there are a lot of fake 2N3055s out there that have a red partnumber on it, those are fake. It should be black
Re: Improved single transistor flyback driver
Dr. Dark Current, Sun May 18 2008, 07:58PM
The upper metal "dome" on TO3 is not really meant to be "pushed", and the transistor is meant to be heatsinked on the bottom metal plate with the screw holes in it.
The dome is not enough thermally conductive for connecting to a heatsink.
Dr. Dark Current, Sun May 18 2008, 07:58PM
The upper metal "dome" on TO3 is not really meant to be "pushed", and the transistor is meant to be heatsinked on the bottom metal plate with the screw holes in it.
The dome is not enough thermally conductive for connecting to a heatsink.
Re: Improved single transistor flyback driver
Mads Barnkob, Thu May 22 2008, 04:50PM
I just put together a little movie with some of the recordings with my version of this flyback driver.
Mads Barnkob, Thu May 22 2008, 04:50PM
I just put together a little movie with some of the recordings with my version of this flyback driver.
Re: Improved single transistor flyback driver
Arcstarter, Thu May 22 2008, 06:14PM
Arcstarter, Thu May 22 2008, 06:14PM
MadsKaizer wrote ...
you should be able to drive it without diode, i did that while experimenting.
Well the diode is there to protect transistor.you should be able to drive it without diode, i did that while experimenting.
Re: Improved single transistor flyback driver
Spedy, Fri May 23 2008, 02:23AM
Cool! I imagine this has been asked already, but does this work w/ modern flybacks? I wanna make sparks with this thing while I'm waiting for my 555 Driver parts to come in. Would the parts for this be available at Radioshack?
Spedy, Fri May 23 2008, 02:23AM
Cool! I imagine this has been asked already, but does this work w/ modern flybacks? I wanna make sparks with this thing while I'm waiting for my 555 Driver parts to come in. Would the parts for this be available at Radioshack?
Re: Improved single transistor flyback driver
Firefox, Fri May 23 2008, 02:38AM
As many people have commented, you should be able to lash a bunch of parts together from the monitor board. I know thats where all the parts I used for my second one came from.
Firefox, Fri May 23 2008, 02:38AM
As many people have commented, you should be able to lash a bunch of parts together from the monitor board. I know thats where all the parts I used for my second one came from.
Re: Improved single transistor flyback driver
quicksilver, Fri May 23 2008, 01:41PM
By "modern" I assume you mean those without a rectifier. Absolutely; it's works just fine. There are perhaps significant initial performance differences between the most basic original design of LOPT and the most common today - but you may find that the "modern" common ones often preform with differing & longer arcs! The issue is what use you are to put them to after you get them running. That's where the "older" type has some flexibility.
Firefox's idea is (IMO) the best way to go. You will learn and have on hand some of the most useful parts for this hobby. I continually tear into a varied collection of old items and now have a collection of materials that would actually cost several thousand dollars if I were to have bought them.
This hobby is actually FREE! If you continually look for the "sources", you'll have more than enough to have fun for years. Somewhere on the Forum, someone composed a list of sources existing of thrown away items and at last count there was over 20 pieces of "junk" that would give you everything that Radio Shack could never provide.
quicksilver, Fri May 23 2008, 01:41PM
By "modern" I assume you mean those without a rectifier. Absolutely; it's works just fine. There are perhaps significant initial performance differences between the most basic original design of LOPT and the most common today - but you may find that the "modern" common ones often preform with differing & longer arcs! The issue is what use you are to put them to after you get them running. That's where the "older" type has some flexibility.
Firefox's idea is (IMO) the best way to go. You will learn and have on hand some of the most useful parts for this hobby. I continually tear into a varied collection of old items and now have a collection of materials that would actually cost several thousand dollars if I were to have bought them.
This hobby is actually FREE! If you continually look for the "sources", you'll have more than enough to have fun for years. Somewhere on the Forum, someone composed a list of sources existing of thrown away items and at last count there was over 20 pieces of "junk" that would give you everything that Radio Shack could never provide.
Re: Improved single transistor flyback driver
Dr. Dark Current, Fri May 23 2008, 02:01PM
With my original driver and AC transformer I got something like 20KV (sparks igniting at 2cm), the modern potted transformers have usually 2x or more turns than the "old" type, so I can imagine 40+KV could be possible with this driver and some tunning. I actually wanted to try this but I am extremely lazy, maybe in a week or so I'll get to it.
Dr. Dark Current, Fri May 23 2008, 02:01PM
With my original driver and AC transformer I got something like 20KV (sparks igniting at 2cm), the modern potted transformers have usually 2x or more turns than the "old" type, so I can imagine 40+KV could be possible with this driver and some tunning. I actually wanted to try this but I am extremely lazy, maybe in a week or so I'll get to it.
Re: Improved single transistor flyback driver
Spedy, Fri May 23 2008, 11:32PM
Cool There are atleast 2 GIANT power-transistor looking thingies in this monitor, but I'm pretty sure which one was driving the flyback. I'll have to do some de-soldering at some point, but it looks like almost all the parts I need are in the monitor or in my junk box...
Spedy, Fri May 23 2008, 11:32PM
Cool There are atleast 2 GIANT power-transistor looking thingies in this monitor, but I'm pretty sure which one was driving the flyback. I'll have to do some de-soldering at some point, but it looks like almost all the parts I need are in the monitor or in my junk box...
Re: Improved single transistor flyback driver
Antonio, Sat May 24 2008, 12:02AM
Look for the part number here, to get the data sheet:
It may be also interesting to have the schematic diagram of the monitor, here:
The two big things are probably a high-voltage transistor and a diode (just what is needed). If you are lucky, there is also a high-voltage mosfet.
Antonio, Sat May 24 2008, 12:02AM
Look for the part number here, to get the data sheet:
It may be also interesting to have the schematic diagram of the monitor, here:
The two big things are probably a high-voltage transistor and a diode (just what is needed). If you are lucky, there is also a high-voltage mosfet.
Re: Improved single transistor flyback driver
Spedy, Sat May 24 2008, 12:13AM
Got the data sheet off of google. Its a "diffused power semiconductor" from Philips. What are the rating symbols I should be looking for? I see Vcesm, Vceo, ect.. It has an anti-parallel diode and a small resistor from base to emiter..
Look at the philips datasheet.
I also have the perfect capacitor, .47uF 250v. I'm pretty sure its a metal film. I've got plenty of HUGE diodes in that crt set if I need em..
Edit: I have found what LOOKS like a suitable diode but the data sheet results says its a 3-phase rectifier.. would this be ok? It only has 2 leads and I'd expect more on a 3 phase rec. It came from a MO
Double edit: Awesome, Power mosfet. It doesn't have the data sheet, but it's very close to the two results that came up.
SSH6N80. the results were -70 and -90 on the end instead of -80
Spedy, Sat May 24 2008, 12:13AM
Got the data sheet off of google. Its a "diffused power semiconductor" from Philips. What are the rating symbols I should be looking for? I see Vcesm, Vceo, ect.. It has an anti-parallel diode and a small resistor from base to emiter..
Look at the philips datasheet.
I also have the perfect capacitor, .47uF 250v. I'm pretty sure its a metal film. I've got plenty of HUGE diodes in that crt set if I need em..
Edit: I have found what LOOKS like a suitable diode but the data sheet results says its a 3-phase rectifier.. would this be ok? It only has 2 leads and I'd expect more on a 3 phase rec. It came from a MO
Double edit: Awesome, Power mosfet. It doesn't have the data sheet, but it's very close to the two results that came up.
SSH6N80. the results were -70 and -90 on the end instead of -80
Re: Improved single transistor flyback driver
Antonio, Sat May 24 2008, 01:27AM
This transistor already has a diode in parallel with it.
The important parameters are the maximum voltage (1500 V) and the collector current (8 A). A separated diode for use with a similar transistor should be a fast diode rated also at 1500 V. In monitors it's usual to find one looking as a transistor with 2 pins attached to the same heat sink of the power transistor. Several fast diodes rated at lower voltages, in the conventional axial form, can be found too.
Antonio, Sat May 24 2008, 01:27AM
This transistor already has a diode in parallel with it.
The important parameters are the maximum voltage (1500 V) and the collector current (8 A). A separated diode for use with a similar transistor should be a fast diode rated also at 1500 V. In monitors it's usual to find one looking as a transistor with 2 pins attached to the same heat sink of the power transistor. Several fast diodes rated at lower voltages, in the conventional axial form, can be found too.
Re: Improved single transistor flyback driver
Spedy, Sat May 24 2008, 01:34AM
Err.. I assume you mean I DON'T need another diode for that one. All I need now are the big fat resistors!
Edit: Is the 4700uF cap absolutely necessary? For some reason I don;t have that value in stock and don;t want to pay the prices at radioshack. I do have a ready-made bank of 4400uF. Would that work?
Spedy, Sat May 24 2008, 01:34AM
Err.. I assume you mean I DON'T need another diode for that one. All I need now are the big fat resistors!
Edit: Is the 4700uF cap absolutely necessary? For some reason I don;t have that value in stock and don;t want to pay the prices at radioshack. I do have a ready-made bank of 4400uF. Would that work?
Re: Improved single transistor flyback driver
Weston, Sat May 24 2008, 04:04AM
I think you need .47 uf.
Weston, Sat May 24 2008, 04:04AM
I think you need .47 uf.
Re: Improved single transistor flyback driver
Dr. Dark Current, Sat May 24 2008, 07:02AM
The 4700uF cap is for filtering and/or proecting your power supply, so the value is not really critical. if you already have a dc power supply you can probably use 1000uF or less.
Dr. Dark Current, Sat May 24 2008, 07:02AM
The 4700uF cap is for filtering and/or proecting your power supply, so the value is not really critical. if you already have a dc power supply you can probably use 1000uF or less.
Re: Improved single transistor flyback driver
quicksilver, Sat May 24 2008, 02:31PM
BELIEVE ME....you may really NEED that cap. (I don't think the value has to right on the money however). If you hunt around enough, you may find a "winner" of a LOPT.
I got one from a huge screen projection TV that blows the doors off anything I have ever used before. Even with the "mini-single transistor" driver I was getting arcs of 3cm and the spray was so violent that the display back into the PS was fouled (bizarre mottled numbering on the digital read-outs).
The cap I used stopped that and arcs went out cleaner and more controllably. It was a 4500 but worked fine.
ALLDATA is great. I discovered that some weeks back when I got several monitors to do at once and wanted to pick the good stuff off fast and not waste time on low voltage material or rectifiers that looked like transistors, etc. This thread is developing some very important issues of a wider range in that the identification of useful materials for any project is occasionally overlooked if one person has access to unique stuff and it's not an "off the shelf item".
)
quicksilver, Sat May 24 2008, 02:31PM
BELIEVE ME....you may really NEED that cap. (I don't think the value has to right on the money however). If you hunt around enough, you may find a "winner" of a LOPT.
I got one from a huge screen projection TV that blows the doors off anything I have ever used before. Even with the "mini-single transistor" driver I was getting arcs of 3cm and the spray was so violent that the display back into the PS was fouled (bizarre mottled numbering on the digital read-outs).
The cap I used stopped that and arcs went out cleaner and more controllably. It was a 4500 but worked fine.
ALLDATA is great. I discovered that some weeks back when I got several monitors to do at once and wanted to pick the good stuff off fast and not waste time on low voltage material or rectifiers that looked like transistors, etc. This thread is developing some very important issues of a wider range in that the identification of useful materials for any project is occasionally overlooked if one person has access to unique stuff and it's not an "off the shelf item".
)
Re: Improved single transistor flyback driver
Spedy, Sat May 24 2008, 04:33PM
Cool, thanks. Can't wait to get this thing up and running!
(now to chop the filter cap off of my failed SSTC..)
I used to have a ton of 5watt resistors from the same CRT, but the bag disappeared... =/
Spedy, Sat May 24 2008, 04:33PM
Cool, thanks. Can't wait to get this thing up and running!
(now to chop the filter cap off of my failed SSTC..)
I used to have a ton of 5watt resistors from the same CRT, but the bag disappeared... =/
Re: Improved single transistor flyback driver
Dr. Dark Current, Sun May 25 2008, 09:17PM
Here is the promised run with a DC flyback
Approx. 40kV. I used: 390R/2W, 10(!)R/6W, 8 pri. turns, 3 feedback turns, 0.56uF cap, KD606 transistor (made by "Tesla", long discontinued, but it's the best transistor for the single transistor driver I ever had...) gets just little warm after short runs.
I'll try to remove some primary turns and set the operating point so I get more kV out with the same power...
Dr. Dark Current, Sun May 25 2008, 09:17PM
Here is the promised run with a DC flyback
Approx. 40kV. I used: 390R/2W, 10(!)R/6W, 8 pri. turns, 3 feedback turns, 0.56uF cap, KD606 transistor (made by "Tesla", long discontinued, but it's the best transistor for the single transistor driver I ever had...) gets just little warm after short runs.
I'll try to remove some primary turns and set the operating point so I get more kV out with the same power...
Re: Improved single transistor flyback driver
Antonio, Sun May 25 2008, 11:18PM
To determine the voltage precisely, produce sparks between balls. The spark length between points depends on many details, and is easily 3 times longer.
This is 20 kV:
A good formula for the voltage for a spark between two identical balls is:
V=E*4*d/(d/R+1+sqrt((d/R+1)^2+8))
E=30000 V/cm
d=spark length (cm)
R=ball radius (cm)
(sqrt=square root)
1 cm sparks between balls with 2 cm radius gives 25523 V
Antonio, Sun May 25 2008, 11:18PM
To determine the voltage precisely, produce sparks between balls. The spark length between points depends on many details, and is easily 3 times longer.
This is 20 kV:
A good formula for the voltage for a spark between two identical balls is:
V=E*4*d/(d/R+1+sqrt((d/R+1)^2+8))
E=30000 V/cm
d=spark length (cm)
R=ball radius (cm)
(sqrt=square root)
1 cm sparks between balls with 2 cm radius gives 25523 V
Re: Improved single transistor flyback driver
Spedy, Wed May 28 2008, 02:42AM
So you mean the 390R/2W at the 'top' of the schem. and the 10R/6W at the bottom, right?
Spedy, Wed May 28 2008, 02:42AM
Dr. Monsterarc wrote ...
Here is the promised run with a DC flyback
Approx. 40kV. I used: 390R/2W, 10(!)R/6W, 8 pri. turns, 3 feedback turns, 0.56uF cap, KD606 transistor (made by "Tesla", long discontinued, but it's the best transistor for the single transistor driver I ever had...) gets just little warm after short runs.
I'll try to remove some primary turns and set the operating point so I get more kV out with the same power...
Here is the promised run with a DC flyback
Approx. 40kV. I used: 390R/2W, 10(!)R/6W, 8 pri. turns, 3 feedback turns, 0.56uF cap, KD606 transistor (made by "Tesla", long discontinued, but it's the best transistor for the single transistor driver I ever had...) gets just little warm after short runs.
I'll try to remove some primary turns and set the operating point so I get more kV out with the same power...
So you mean the 390R/2W at the 'top' of the schem. and the 10R/6W at the bottom, right?
Re: Improved single transistor flyback driver
Shaun, Wed May 28 2008, 03:55AM
Antonio, where on earth did you find that formula!? That's a nice one; it sure takes things further than just 1.1kv/mm like i usually use to "measure" voltage.
I think it deserves this though, for ease of understanding:
Shaun, Wed May 28 2008, 03:55AM
Antonio, where on earth did you find that formula!? That's a nice one; it sure takes things further than just 1.1kv/mm like i usually use to "measure" voltage.
I think it deserves this though, for ease of understanding:
Re: Improved single transistor flyback driver
Dr. Dark Current, Wed May 28 2008, 06:09AM
---
what I found out: More feedback turns=more power (but not necesarilly more voltage). Decreasing the value of bottom resistor results in more power and voltage, but the resistor WILL get very hot if you get it too small. The top resistor has minimal effect on performance, so it is best to use the highest value that allows for reliable start-up.
Bigger capacitors tend to produce hotter arcs possibly with decreased output voltage.
Dr. Dark Current, Wed May 28 2008, 06:09AM
Spedy wrote ...
So you mean the 390R/2W at the 'top' of the schem. and the 10R/6W at the bottom, right?
yeahSo you mean the 390R/2W at the 'top' of the schem. and the 10R/6W at the bottom, right?
---
what I found out: More feedback turns=more power (but not necesarilly more voltage). Decreasing the value of bottom resistor results in more power and voltage, but the resistor WILL get very hot if you get it too small. The top resistor has minimal effect on performance, so it is best to use the highest value that allows for reliable start-up.
Bigger capacitors tend to produce hotter arcs possibly with decreased output voltage.
Re: Improved single transistor flyback driver
quicksilver, Wed May 28 2008, 02:27PM
You bring up a very interesting point from what I am just studying. When I was looking at the circuit I believe those resistors to be functioning in parallel even though they exist in a series of two (one after another). If I'm correct and they are functioning in parallel, their collective value will be lower than the lowest one of the two.
Example: We have two resistors, a 22 ohm & a 470 which = 492ohm but the actual resistance would be 21 ohm if they are used as parallel with our circuit. But if we didn't have a 22 & 470 but a 92 & a 400 ohm we would have 75.1 total resistance. I tried playing with the values and that gave me the idea that they were functioning in parallel. If I'm right we could use two resistors & depending upon the values of each those choices would determine the functionality. So this concept playing itself out to the fullest - if we had a 600 & a 20 ohm, our total resistance would be 19.3 ohms....even less than the 470 & 22 original design.
{I also was wondering what you meant by the term "big" in capacitors; voltage or storage...? As I'd like to experiment with that.}
quicksilver, Wed May 28 2008, 02:27PM
Dr. Monsterarc wrote ...
Decreasing the value of bottom resistor results in more power and voltage, but the resistor WILL get very hot if you get it too small. The top resistor has minimal effect on performance, so it is best to use the highest value that allows for reliable start-up.
Bigger capacitors tend to produce hotter arcs possibly with decreased output voltage.
Decreasing the value of bottom resistor results in more power and voltage, but the resistor WILL get very hot if you get it too small. The top resistor has minimal effect on performance, so it is best to use the highest value that allows for reliable start-up.
Bigger capacitors tend to produce hotter arcs possibly with decreased output voltage.
You bring up a very interesting point from what I am just studying. When I was looking at the circuit I believe those resistors to be functioning in parallel even though they exist in a series of two (one after another). If I'm correct and they are functioning in parallel, their collective value will be lower than the lowest one of the two.
Example: We have two resistors, a 22 ohm & a 470 which = 492ohm but the actual resistance would be 21 ohm if they are used as parallel with our circuit. But if we didn't have a 22 & 470 but a 92 & a 400 ohm we would have 75.1 total resistance. I tried playing with the values and that gave me the idea that they were functioning in parallel. If I'm right we could use two resistors & depending upon the values of each those choices would determine the functionality. So this concept playing itself out to the fullest - if we had a 600 & a 20 ohm, our total resistance would be 19.3 ohms....even less than the 470 & 22 original design.
{I also was wondering what you meant by the term "big" in capacitors; voltage or storage...? As I'd like to experiment with that.}
Re: Improved single transistor flyback driver
Spedy, Thu May 29 2008, 12:10AM
Hmm, this could present a problem for me. What if I paralleled a ton of resistors of the same value to get a higher wattage, would the resistance change? Ex: 10x 10ohms in parallel would = less than 10ohms?
Spedy, Thu May 29 2008, 12:10AM
Hmm, this could present a problem for me. What if I paralleled a ton of resistors of the same value to get a higher wattage, would the resistance change? Ex: 10x 10ohms in parallel would = less than 10ohms?
Re: Improved single transistor flyback driver
Tesladownunder, Thu May 29 2008, 12:56AM
This circuit has been around for a long time. I got my circuit from Sam Barros' site and made it up in 2002. Draws 3 A at 20V with 2N3055 for 1/2 inch spark.
TDU
Tesladownunder, Thu May 29 2008, 12:56AM
This circuit has been around for a long time. I got my circuit from Sam Barros' site and made it up in 2002. Draws 3 A at 20V with 2N3055 for 1/2 inch spark.
TDU
Re: Improved single transistor flyback driver
Antonio, Thu May 29 2008, 01:14AM
The formula comes from this document ("North report"):
It is said there that the formula is exact, but it isn't. It is a good approximation, however. The exact expression has an infinite series.
Antonio, Thu May 29 2008, 01:14AM
Shaun wrote ...
Antonio, where on earth did you find that formula!? That's a nice one; it sure takes things further than just 1.1kv/mm like i usually use to "measure" voltage.
I think it deserves this though, for ease of understanding:
Antonio, where on earth did you find that formula!? That's a nice one; it sure takes things further than just 1.1kv/mm like i usually use to "measure" voltage.
I think it deserves this though, for ease of understanding:
The formula comes from this document ("North report"):
It is said there that the formula is exact, but it isn't. It is a good approximation, however. The exact expression has an infinite series.
Re: Improved single transistor flyback driver
flannelhead, Mon Jun 16 2008, 05:43AM
I made a 555 based single MOSFET driver and started with a 440nF cap across the FET. The arc started at 5mm and stretched to 25mm. Then I removed 220nF from the capacitance and the arcs started at 20mm and drawed to 50mm! So tuning is very important.
flannelhead, Mon Jun 16 2008, 05:43AM
I made a 555 based single MOSFET driver and started with a 440nF cap across the FET. The arc started at 5mm and stretched to 25mm. Then I removed 220nF from the capacitance and the arcs started at 20mm and drawed to 50mm! So tuning is very important.
Re: Improved single transistor flyback driver
coffeetable, Wed Oct 21 2009, 06:18PM
Apologies for the thread necromancy, but I figured it was better than posting an all-new thread just for my question;
I'm a newbie. I built the 2n3055 circuit on the wiki, it worked, but they were right to say it leaves you wanting more. So I tried to build this one, with the materials to hand.
The materials at hand are a 2SD1555 transistor (built in damper diode, ~5V threshold voltage) and a 12V power supply. And it doesn't work.
My suspicion is that I'm not delivering enough voltage to turn the transistor on, but I've got no idea how to modify the circuit to fix this. Can anyone help?
(explainations of why the changes you suggest would fix it would be appreciated as well, so that I can actually start to understand what I'm building)
Thanks
coffeetable, Wed Oct 21 2009, 06:18PM
Apologies for the thread necromancy, but I figured it was better than posting an all-new thread just for my question;
I'm a newbie. I built the 2n3055 circuit on the wiki, it worked, but they were right to say it leaves you wanting more. So I tried to build this one, with the materials to hand.
The materials at hand are a 2SD1555 transistor (built in damper diode, ~5V threshold voltage) and a 12V power supply. And it doesn't work.
My suspicion is that I'm not delivering enough voltage to turn the transistor on, but I've got no idea how to modify the circuit to fix this. Can anyone help?
(explainations of why the changes you suggest would fix it would be appreciated as well, so that I can actually start to understand what I'm building)
Thanks
Re: Improved single transistor flyback driver
Dr. Dark Current, Wed Oct 21 2009, 07:37PM
You want a transistor similar to 2n3055, with <300V C-E max. voltage, I believe the low voltage ones are made with different process than the high-voltage horizontal output transistors.
EDIT: You can try decreasing the value of the top resistor. The circuit might start oscillating but it will probably work pretty bad with your transistor.
Dr. Dark Current, Wed Oct 21 2009, 07:37PM
coffeetable wrote ...
The materials at hand are a 2SD1555 transistor (built in damper diode, ~5V threshold voltage) and a 12V power supply. And it doesn't work.
That's a HOT, they don't work well in this circuit (probably because of very low Hfe).The materials at hand are a 2SD1555 transistor (built in damper diode, ~5V threshold voltage) and a 12V power supply. And it doesn't work.
You want a transistor similar to 2n3055, with <300V C-E max. voltage, I believe the low voltage ones are made with different process than the high-voltage horizontal output transistors.
EDIT: You can try decreasing the value of the top resistor. The circuit might start oscillating but it will probably work pretty bad with your transistor.
Re: Improved single transistor flyback driver
Zeus, Mon Oct 26 2009, 03:42AM
and 10 mA(the old ones). However RF burn is very bad. It burns tiny holes into your flesh.
I don't want to put you off but be careful around HFHV.
Zeus, Mon Oct 26 2009, 03:42AM
Dr. Kilovolt wrote ...
(like draw arcs to earthed wire and stay away from the HV output) I think not too dangerous currents are involved, probably below 20mA on the output.
You would be very lucky to get 20 mA out of a flyback. They generaly put out 5 mA(the new ones)spark wrote ...
Can this circuit produce dangerous currents if a small FBT and 12V is used? I really wanna build this circuit but first I want to know how dangerous it is.
No circuit is dangerous if you observe safety precautions Can this circuit produce dangerous currents if a small FBT and 12V is used? I really wanna build this circuit but first I want to know how dangerous it is.
(like draw arcs to earthed wire and stay away from the HV output) I think not too dangerous currents are involved, probably below 20mA on the output.and 10 mA(the old ones). However RF burn is very bad. It burns tiny holes into your flesh.
I don't want to put you off but be careful around HFHV.
Re: Improved single transistor flyback driver
Dr. Dark Current, Mon Oct 26 2009, 07:24AM
Where they put out 5mA? In the TV? You forgot that our drivers can push X-times more power through the transformer than it did put out in the TV
With the old-style AC ones, I think 50mA is not a problem (based on the appearance/thickness of the arc.)
Remember that if your driver draws e.g. 500W from the wall (most good flybacks can take this for a short time), the transformer can see over 1500VA. And with 20kV on the output, that's maybe something like 75mA short circuit current.
Dr. Dark Current, Mon Oct 26 2009, 07:24AM
Zeus wrote ...
You would be very lucky to get 20 mA out of a flyback. They generaly put out 5 mA(the new ones)
and 10 mA(the old ones). However RF burn is very bad. It burns tiny holes into your flesh.
I don't want to put you off but be careful around HFHV.
You would be very lucky to get 20 mA out of a flyback. They generaly put out 5 mA(the new ones)
and 10 mA(the old ones). However RF burn is very bad. It burns tiny holes into your flesh.
I don't want to put you off but be careful around HFHV.
Where they put out 5mA? In the TV? You forgot that our drivers can push X-times more power through the transformer than it did put out in the TV
With the old-style AC ones, I think 50mA is not a problem (based on the appearance/thickness of the arc.)
Remember that if your driver draws e.g. 500W from the wall (most good flybacks can take this for a short time), the transformer can see over 1500VA. And with 20kV on the output, that's maybe something like 75mA short circuit current.
Re: Improved single transistor flyback driver
Zeus, Tue Oct 27 2009, 01:59AM
In regards to old flybacks 50 mA is possible because my hacked CFL circuit can melt glass and salt.
However in this circuit 5 to 20 mA is likely. HFHV to my understanding is not as lethal as DC because
AC will not lock musles like DC.
A CRT needs a electrostatic field so the current only needs to be around 100 micro amps.
Zeus, Tue Oct 27 2009, 01:59AM
In regards to old flybacks 50 mA is possible because my hacked CFL circuit can melt glass and salt.
However in this circuit 5 to 20 mA is likely. HFHV to my understanding is not as lethal as DC because
AC will not lock musles like DC.
A CRT needs a electrostatic field so the current only needs to be around 100 micro amps.
Re: Improved single transistor flyback driver
aris, Sun Jun 13 2010, 02:40PM
sorry for reply on an old topic!I made this circuit..I use 500ohm resistor(combination of 3w and 10w resistors),18ohm resistor(combination of 10w resistors),25v 4400uf,250v~0,33uf(gpf type).Also i use this transistor:http://pdf1.alldatasheet.com/datasheet- pdf/view/12991/PANASONIC/2SC5406A.html and i dont take anything!I used a 7v 3A battery!The problem maybe is the materials or the power supply?
Sorry for my English!
aris, Sun Jun 13 2010, 02:40PM
sorry for reply on an old topic!I made this circuit..I use 500ohm resistor(combination of 3w and 10w resistors),18ohm resistor(combination of 10w resistors),25v 4400uf,250v~0,33uf(gpf type).Also i use this transistor:http://pdf1.alldatasheet.com/datasheet- pdf/view/12991/PANASONIC/2SC5406A.html and i dont take anything!I used a 7v 3A battery!The problem maybe is the materials or the power supply?
Sorry for my English!
Re: Improved single transistor flyback driver
Wolfram, Sun Jun 13 2010, 03:12PM
Wolfram, Sun Jun 13 2010, 03:12PM
aris wrote ...
sorry for reply on an old topic!I made this circuit..I use 500ohm resistor(combination of 3w and 10w resistors),18ohm resistor(combination of 10w resistors),25v 4400uf,250v~0,33uf(gpf type).Also i use this transistor:http://pdf1.alldatasheet.com/datasheet- pdf/view/12991/PANASONIC/2SC5406A.html and i dont take anything!I used a 7v 3A battery!The problem maybe is the materials or the power supply?
Sorry for my English!
sorry for reply on an old topic!I made this circuit..I use 500ohm resistor(combination of 3w and 10w resistors),18ohm resistor(combination of 10w resistors),25v 4400uf,250v~0,33uf(gpf type).Also i use this transistor:http://pdf1.alldatasheet.com/datasheet- pdf/view/12991/PANASONIC/2SC5406A.html and i dont take anything!I used a 7v 3A battery!The problem maybe is the materials or the power supply?
Sorry for my English!
That's a HOT, they don't work well in this circuit (probably because of very low Hfe).
You want a transistor similar to 2n3055, with <300V C-E max. voltage, I believe the low voltage ones are made with different process than the high-voltage horizontal output transistors.
EDIT: You can try decreasing the value of the top resistor. The circuit might start oscillating but it will probably work pretty bad with your transistor.
Re: Improved single transistor flyback driver
aris, Sun Jun 13 2010, 03:32PM
But this transistor work with the original driver..I forgot to mention that i use this diode(BY397P:http://www.datasheetcatalog.org/ datasheet/GeneralSemiconductor/mXusvqx.pdf).Also here are some of my capacitors:
Which of them is best?!
aris, Sun Jun 13 2010, 03:32PM
But this transistor work with the original driver..I forgot to mention that i use this diode(BY397P:http://www.datasheetcatalog.org/ datasheet/GeneralSemiconductor/mXusvqx.pdf).Also here are some of my capacitors:
Which of them is best?!
Re: Improved single transistor flyback driver
Hellraiser, Sun Jun 13 2010, 07:31PM
Hey guys, i need some help with my driver.
1 i use this diode: D31F6 (SIYU)
2 my cap is 3500uF 50V
3 and second Cap is a 0.22uF (The same XG-VF posted here but lower)
4 i use 22R 10W
5 i use a flyback from 15" LG and use 8 turns 18AWG for primary and 3 turns 22AWG for feedback
My 2n3055 toshiba transistor mounted in cooler and keep cooled all time, my pilot lamp burns inside and a metal wire smelts but the sparks only shows at almost short circuiting the cables from flyback and i need to do this to see the sparks with i'm powering with two batteries with 6V and 2.5A in series.
Please help-me i need to know where is the problem, if is my driver or power source or i made some wong substitutions.
Some pics form my driver "working" with this lower performer runing from those battery 12V, 2.5A.
Hellraiser, Sun Jun 13 2010, 07:31PM
Hey guys, i need some help with my driver.
1 i use this diode: D31F6 (SIYU)
2 my cap is 3500uF 50V
3 and second Cap is a 0.22uF (The same XG-VF posted here but lower)
4 i use 22R 10W
5 i use a flyback from 15" LG and use 8 turns 18AWG for primary and 3 turns 22AWG for feedback
My 2n3055 toshiba transistor mounted in cooler and keep cooled all time, my pilot lamp burns inside and a metal wire smelts but the sparks only shows at almost short circuiting the cables from flyback and i need to do this to see the sparks with i'm powering with two batteries with 6V and 2.5A in series.
Please help-me i need to know where is the problem, if is my driver or power source or i made some wong substitutions.
Some pics form my driver "working" with this lower performer runing from those battery 12V, 2.5A.
Re: Improved single transistor flyback driver
Mads Barnkob, Sun Jun 13 2010, 08:37PM
What is the voltage over the batteries when you draw an arc? They could be discharged?
Mads Barnkob, Sun Jun 13 2010, 08:37PM
Hellraiser wrote ...
Hey guys, i need some help with my driver.
1 i use this diode: D31F6 (SIYU)
2 my cap is 3500uF 50V
3 and second Cap is a 0.22uF (The same XG-VF posted here but lower)
4 i use 22R 10W
5 i use a flyback from 15" LG and use 8 turns 18AWG for primary and 3 turns 22AWG for feedback
My 2n3055 toshiba transistor mounted in cooler and keep cooled all time, my pilot lamp burns inside and a metal wire smelts but the sparks only shows at almost short circuiting the cables from flyback and i need to do this to see the sparks with i'm powering with two batteries with 6V and 2.5A in series.
Please help-me i need to know where is the problem, if is my driver or power source or i made some wong substitutions.
Some pics form my driver "working" with this lower performer runing from those battery 12V, 2.5A.
@edit:
Another question my 0.22uF capacitor has polarity?
Hey guys, i need some help with my driver.
1 i use this diode: D31F6 (SIYU)
2 my cap is 3500uF 50V
3 and second Cap is a 0.22uF (The same XG-VF posted here but lower)
4 i use 22R 10W
5 i use a flyback from 15" LG and use 8 turns 18AWG for primary and 3 turns 22AWG for feedback
My 2n3055 toshiba transistor mounted in cooler and keep cooled all time, my pilot lamp burns inside and a metal wire smelts but the sparks only shows at almost short circuiting the cables from flyback and i need to do this to see the sparks with i'm powering with two batteries with 6V and 2.5A in series.
Please help-me i need to know where is the problem, if is my driver or power source or i made some wong substitutions.
Some pics form my driver "working" with this lower performer runing from those battery 12V, 2.5A.
@edit:
Another question my 0.22uF capacitor has polarity?
What is the voltage over the batteries when you draw an arc? They could be discharged?
Re: Improved single transistor flyback driver
Hellraiser, Sun Jun 13 2010, 09:29PM
The driver drains all tension from battery and it shows decresing until 0V but the battery shows 13V disconect and i use it for tests when i built this driver today.
You think the battery is insuficient or i built it with wong itens?
I token those batteries from newer emergency light about 2 weeks they're in constanting float charger.
Hellraiser, Sun Jun 13 2010, 09:29PM
The driver drains all tension from battery and it shows decresing until 0V but the battery shows 13V disconect and i use it for tests when i built this driver today.
You think the battery is insuficient or i built it with wong itens?
I token those batteries from newer emergency light about 2 weeks they're in constanting float charger.
Re: Improved single transistor flyback driver
aris, Mon Jun 14 2010, 12:11PM
i bought a 2n3055 transistor and two 0,22 and 0,47 mtk capacitors so i am to way for second try!I think to use a pc psu 12v 16A the 2n3055 transistor will could carry this power?
aris, Mon Jun 14 2010, 12:11PM
i bought a 2n3055 transistor and two 0,22 and 0,47 mtk capacitors so i am to way for second try!I think to use a pc psu 12v 16A the 2n3055 transistor will could carry this power?
Re: Improved single transistor flyback driver
Mads Barnkob, Mon Jun 14 2010, 01:50PM
You found your problem, use a transformer instead.
Just because the batteries was pulled out of a float charge setup does not mean they are any good...
Mads Barnkob, Mon Jun 14 2010, 01:50PM
Hellraiser wrote ...
The driver drains all tension from battery and it shows decreasing until 0V.
The driver drains all tension from battery and it shows decreasing until 0V.
You found your problem, use a transformer instead.
Just because the batteries was pulled out of a float charge setup does not mean they are any good...
Re: Improved single transistor flyback driver
Hellraiser, Mon Jun 14 2010, 02:24PM
Thank you guys i will try run this in a power source!
Another question i have here a real 350W seventeam power source for pc, once i test trading a zener 5V reference for CI, for 8.2V and get 14V and if take out this diode i will have arround 30V can i run the driver with that source?
You guys know how to use that PC source in this driver?
I allready destroy a working LG CTR for built this, i wanna see this runing!
Hellraiser, Mon Jun 14 2010, 02:24PM
Mads Barnkob wrote ...
You found your problem, use a transformer instead.
Just because the batteries was pulled out of a float charge setup does not mean they are any good...
Hellraiser wrote ...
The driver drains all tension from battery and it shows decreasing until 0V.
The driver drains all tension from battery and it shows decreasing until 0V.
You found your problem, use a transformer instead.
Just because the batteries was pulled out of a float charge setup does not mean they are any good...
Thank you guys i will try run this in a power source!
Another question i have here a real 350W seventeam power source for pc, once i test trading a zener 5V reference for CI, for 8.2V and get 14V and if take out this diode i will have arround 30V can i run the driver with that source?
You guys know how to use that PC source in this driver?
I allready destroy a working LG CTR for built this, i wanna see this runing!
Re: Improved single transistor flyback driver
aris, Mon Jun 14 2010, 06:56PM
i bought a RGP30M diode rate at 3A and 1000v..Its ok or it must be 200v?Also if i use a 12v 16A pc psu this diode will be ok?And something else,a 2n3055 transistor is ok for a 12v 16A power source?
aris, Mon Jun 14 2010, 06:56PM
i bought a RGP30M diode rate at 3A and 1000v..Its ok or it must be 200v?Also if i use a 12v 16A pc psu this diode will be ok?And something else,a 2n3055 transistor is ok for a 12v 16A power source?
Re: Improved single transistor flyback driver
Dr. Dark Current, Tue Jun 15 2010, 01:20PM
aris: the diode is fine, the transistor too. Just beware of fakes, there are a lot of fakes of the 2nN3055 transistor. The current on the power supply is just the maximum it can put out, the circuit will draw how much it needs (and with 12V the performance probably wont be great, or it wont start at all. If it doesn't start, decrease the value of the 470ohm resistor).
Dr. Dark Current, Tue Jun 15 2010, 01:20PM
aris: the diode is fine, the transistor too. Just beware of fakes, there are a lot of fakes of the 2nN3055 transistor. The current on the power supply is just the maximum it can put out, the circuit will draw how much it needs (and with 12V the performance probably wont be great, or it wont start at all. If it doesn't start, decrease the value of the 470ohm resistor).
Re: Improved single transistor flyback driver
aris, Tue Jun 15 2010, 03:00PM
thank you very much!I have to make a dicission:An ATX pc psu power supply or a AT?Which is better for this circuit and more confortable and easy in use?
aris, Tue Jun 15 2010, 03:00PM
thank you very much!I have to make a dicission:An ATX pc psu power supply or a AT?Which is better for this circuit and more confortable and easy in use?
Re: Improved single transistor flyback driver
aris, Sat Jun 26 2010, 03:56PM
I made the circuit and i power it up with a pc psu 12v 12A....When i turned on the power supply i didn't take spark but the moment i turn it off i take an instantly spark...After i disconnect the 250v capacitor and power on the circuit, now i have a good purple spark...Then i try to connect again the capacitor and IT WORKS,i have a burnt purple spark!The bad point is that when i turn off again the power supply and i wait 5minutes..Then i power it up and again nothing,i can take again an instantly spark when i turn it off....
I think the problem is the transistor(2n3055) because the circuit stop to work when it become cool,and i need to connect-disconnect the capacitor.I have tried 4-5capacitors of different uF but all have the same problem..It;s very strange:/
What is going wrong?
aris, Sat Jun 26 2010, 03:56PM
I made the circuit and i power it up with a pc psu 12v 12A....When i turned on the power supply i didn't take spark but the moment i turn it off i take an instantly spark...After i disconnect the 250v capacitor and power on the circuit, now i have a good purple spark...Then i try to connect again the capacitor and IT WORKS,i have a burnt purple spark!The bad point is that when i turn off again the power supply and i wait 5minutes..Then i power it up and again nothing,i can take again an instantly spark when i turn it off....
I think the problem is the transistor(2n3055) because the circuit stop to work when it become cool,and i need to connect-disconnect the capacitor.I have tried 4-5capacitors of different uF but all have the same problem..It;s very strange:/
What is going wrong?
Re: Improved single transistor flyback driver
aris, Mon Jun 28 2010, 10:19AM
When i power up the circuit don't work but if i discharge with a screwdriver the 250v capacitor its starts to work...What is going wrong?
aris, Mon Jun 28 2010, 10:19AM
When i power up the circuit don't work but if i discharge with a screwdriver the 250v capacitor its starts to work...What is going wrong?
Re: Improved single transistor flyback driver
tritium, Thu Jul 22 2010, 05:28PM
i have build this circuit for my homemade hv-transformer to zap bugs away, and it works allmost perfect.
but when the secondary is short, the circuit is not oscilating anymore, what is the best thing i can try?
1: feedback closer to the core (is now over the sec. winding.
2: change the falue of the resistors
3: more turns of the feedback coil
4: something else
tritium, Thu Jul 22 2010, 05:28PM
i have build this circuit for my homemade hv-transformer to zap bugs away, and it works allmost perfect.
but when the secondary is short, the circuit is not oscilating anymore, what is the best thing i can try?
1: feedback closer to the core (is now over the sec. winding.
2: change the falue of the resistors
3: more turns of the feedback coil
4: something else
Re: Improved single transistor flyback driver
GhostNull, Fri Jul 30 2010, 12:41PM
This should be added to the 4hv Wiki
GhostNull, Fri Jul 30 2010, 12:41PM
This should be added to the 4hv Wiki
Re: Improved single transistor flyback driver
811a vttc, Sat Aug 14 2010, 05:29AM
Um i just tested it on my flyback it oscillated but it killed my flyback
so i hooked it up to a micro sstc using a ferite core transformer to get the oscilations then i ran that into my sstc, it worked!amazed
811a vttc, Sat Aug 14 2010, 05:29AM
Um i just tested it on my flyback it oscillated but it killed my flyback
so i hooked it up to a micro sstc using a ferite core transformer to get the oscilations then i ran that into my sstc, it worked!amazed
Re: Improved single transistor flyback driver
tritium, Mon Aug 23 2010, 03:54PM
is this paralel resonance? the primary and cap are in serie.
I think it is serie resonance or do I understand something wrong?
tritium, Mon Aug 23 2010, 03:54PM
Dr. Kilovolt wrote ...
The cap and the primary winding form a parallel resonant circuit and the driver starts to operate in "pseudo class E" mode, not exact Class E switching, but it improves performance greatly and decreases transistor heating (mainly because it has more time to turn off - Toff switching losses are minimised).
The cap and the primary winding form a parallel resonant circuit and the driver starts to operate in "pseudo class E" mode, not exact Class E switching, but it improves performance greatly and decreases transistor heating (mainly because it has more time to turn off - Toff switching losses are minimised).
is this paralel resonance? the primary and cap are in serie.
I think it is serie resonance or do I understand something wrong?
Re: Improved single transistor flyback driver
Dr. Dark Current, Mon Aug 23 2010, 03:58PM
its parallel resonance, it doesn't matter if you connect the resonant cap to the +V or GND rail, because they are AC coupled by the filter cap.
Dr. Dark Current, Mon Aug 23 2010, 03:58PM
its parallel resonance, it doesn't matter if you connect the resonant cap to the +V or GND rail, because they are AC coupled by the filter cap.
Re: Improved single transistor flyback driver
tritium, Mon Aug 23 2010, 05:12PM
is it the same like this?
tritium, Mon Aug 23 2010, 05:12PM
is it the same like this?
Re: Improved single transistor flyback driver
Dr. Dark Current, Mon Aug 23 2010, 05:24PM
yes its the same, just I'd rather put the cap across the transistor because of wiring inductances which might result in some ringing (but probably of no significance).
Dr. Dark Current, Mon Aug 23 2010, 05:24PM
yes its the same, just I'd rather put the cap across the transistor because of wiring inductances which might result in some ringing (but probably of no significance).
Re: Improved single transistor flyback driver
tritium, Mon Aug 23 2010, 06:21PM
I think we can run this circuit without high power resistors, if we know the Al of the core and also L of the feedback.
Maybe I don't understand everything, but I will just try to improve this circuit.
@dr kilovolt,
how did you calculate the resistor values?
tritium, Mon Aug 23 2010, 06:21PM
I think we can run this circuit without high power resistors, if we know the Al of the core and also L of the feedback.
Maybe I don't understand everything, but I will just try to improve this circuit.
@dr kilovolt,
how did you calculate the resistor values?
Re: Improved single transistor flyback driver
Dr. Dark Current, Mon Aug 23 2010, 07:12PM
Ps. This circuit is a little outdated, now I would maybe do it a bit different, but have no time for testing the circuits right now.
Dr. Dark Current, Mon Aug 23 2010, 07:12PM
tritium wrote ...
@dr kilovolt,
how did you calculate the resistor values
The bottom resistor sets the turn-off current (via the transistor's Hfe) and in turn output power. The upper resistor just needs to provide above 0.7V on the divider output, so the transistor doesn't stay turned off.@dr kilovolt,
how did you calculate the resistor values
Ps. This circuit is a little outdated, now I would maybe do it a bit different, but have no time for testing the circuits right now.
Re: Improved single transistor flyback driver
quicksilver, Mon Aug 23 2010, 10:58PM
I've tweaked this circuit many times and that's what I've come to understand (the bottom resistor is turn-off current) However even 5w is a touch light in certain circumstances: do not go to anything lower than 5w; in fact it appears to preform w/ less stress on a TO-220 package if yo raise that to 10w. Using a MJ13009 x-sistor I got some fair performance with anything from a 18-24ohm.
I happen to like it because it's so "flexible". I beefed up all components and it handled quite a bit of power. I have compared differing caps and gotten great results with higher (than 4700uf) capacitance (& voltage). It's a far cry from a ZVS but for it's potential size; it's a lot of fun.
I HAVE tried putting a cap across the x-sister & I like it better.
The fact that you can make it SO small that the only real room is taken by the heat-sink makes it fun to put in a small box w/ the flyback.
quicksilver, Mon Aug 23 2010, 10:58PM
I've tweaked this circuit many times and that's what I've come to understand (the bottom resistor is turn-off current) However even 5w is a touch light in certain circumstances: do not go to anything lower than 5w; in fact it appears to preform w/ less stress on a TO-220 package if yo raise that to 10w. Using a MJ13009 x-sistor I got some fair performance with anything from a 18-24ohm.
I happen to like it because it's so "flexible". I beefed up all components and it handled quite a bit of power. I have compared differing caps and gotten great results with higher (than 4700uf) capacitance (& voltage). It's a far cry from a ZVS but for it's potential size; it's a lot of fun.
I HAVE tried putting a cap across the x-sister & I like it better.
The fact that you can make it SO small that the only real room is taken by the heat-sink makes it fun to put in a small box w/ the flyback.
Re: Improved single transistor flyback driver
tritium, Sat Aug 28 2010, 05:43PM
@dr. kilovolt
are you willing to post your new design?
tritium, Sat Aug 28 2010, 05:43PM
@dr. kilovolt
are you willing to post your new design?
Re: Improved single transistor flyback driver
Alex M, Tue Jul 05 2011, 10:10PM
I am going to give this a try but have one question, is the 4700uF cap across the power supply essential as I am using a 12 7AH lead acid battery for my supply (which works fine for the regular 2n3055 version, giving 1 1/2 inch arcs from one of my flybacks!). Or is it only needed when using a power supply where ripple current might be an issue?
Thanks.
Alex M, Tue Jul 05 2011, 10:10PM
I am going to give this a try but have one question, is the 4700uF cap across the power supply essential as I am using a 12 7AH lead acid battery for my supply (which works fine for the regular 2n3055 version, giving 1 1/2 inch arcs from one of my flybacks!). Or is it only needed when using a power supply where ripple current might be an issue?
Thanks.
Re: Improved single transistor flyback driver
quicksilver, Mon Jul 11 2011, 07:12PM
Doesn't require 4.7K capacitance but it needs to be fairly close & (in terms of voltage) a good idea is using one approx 1/3 larger than input voltage. RE: heat sinking & related issues, consider the current level of the battery as well (use heavy traces or wiring). The circuit itself is very flexible and works well for what it is. I really like the 2N3773 and if you have a decent heat sink the MJE13007 (I've also used 13009 savaged & all was fine) have gotten great results.
quicksilver, Mon Jul 11 2011, 07:12PM
Doesn't require 4.7K capacitance but it needs to be fairly close & (in terms of voltage) a good idea is using one approx 1/3 larger than input voltage. RE: heat sinking & related issues, consider the current level of the battery as well (use heavy traces or wiring). The circuit itself is very flexible and works well for what it is. I really like the 2N3773 and if you have a decent heat sink the MJE13007 (I've also used 13009 savaged & all was fine) have gotten great results.
Re: Improved single transistor flyback driver
SaberShip, Mon Apr 23 2012, 11:26PM
This is a great circuit! I'm using a MJ15003G transistor and have played around with it alot. I can get some nice 4cm arcs starting at about 1.5cm and the transistor hardly gets warm after several minuets on my 5" heatsink!!
I was wondering if the resonance cap across the transistor could be applied some how to this circuit using the MJ15003Gs ??
http://www.kronjaeger.com/hv/hv/src/fly/flyback1.png
The website that this schematic comes from is right here:
http://www.kronjaeger.com/hv/hv/src/fly/index.html
Any insight would be appreciated, thanks!
SaberShip, Mon Apr 23 2012, 11:26PM
This is a great circuit! I'm using a MJ15003G transistor and have played around with it alot. I can get some nice 4cm arcs starting at about 1.5cm and the transistor hardly gets warm after several minuets on my 5" heatsink!!
I was wondering if the resonance cap across the transistor could be applied some how to this circuit using the MJ15003Gs ??
http://www.kronjaeger.com/hv/hv/src/fly/flyback1.png
The website that this schematic comes from is right here:
http://www.kronjaeger.com/hv/hv/src/fly/index.html
Any insight would be appreciated, thanks!
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