Flyback Driver inside a PC PSU box
Dr. Dark Current, Wed Jan 31 2007, 12:06PMHi all, I want to make a flyback driver that will fit incl. the flyback in a PC PSU box. Now I'm wondering if it is a bad thing that the flyback will be inside a metal box, will the metal "steal" power from the flyback? (I don't know much about magnetics
)Re: Flyback Driver inside a PC PSU box
J. Aaron Holmes, Wed Jan 31 2007, 12:35PM
Transformers and CRTs (generally implies flybacks) are found in metal enclosures all the time. I wouldn't think it would be a problem; the vast majority of the flux you care about is going to be in the flyback's metal core. Now, if you were talking big air-core reactors, then you might have to start worrying about induction-heating your PC case.
Of course, putting anything HV in a metal box means there are a lot more places the HV *could* go besides where you intended
Regards,
Aaron, N7OE
J. Aaron Holmes, Wed Jan 31 2007, 12:35PM
Transformers and CRTs (generally implies flybacks) are found in metal enclosures all the time. I wouldn't think it would be a problem; the vast majority of the flux you care about is going to be in the flyback's metal core. Now, if you were talking big air-core reactors, then you might have to start worrying about induction-heating your PC case.
Of course, putting anything HV in a metal box means there are a lot more places the HV *could* go besides where you intended
Regards,
Aaron, N7OE
Re: Flyback Driver inside a PC PSU box
TheMerovingian, Wed Jan 31 2007, 12:53PM
I have done this. Housed a royer flyback driver in a metal psu casing (separate ground of course)
RoyerFlyback
Some static is possible, if you don't ground the casing.
TheMerovingian, Wed Jan 31 2007, 12:53PM
I have done this. Housed a royer flyback driver in a metal psu casing (separate ground of course)
RoyerFlyback
Some static is possible, if you don't ground the casing.
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Wed Jan 31 2007, 01:29PM
Yes, some flybacks in crt's are in metal enclosure, but there they do not work at too high powers, I guess around 50w for a standard flyback. My flyback is going to operate over 300w so I was wondering that if I screw it to the metal case (so the core will be really close to the case), the flyback could inductive heat the case and decrease performance.
Dr. Dark Current, Wed Jan 31 2007, 01:29PM
J. Aaron Holmes wrote ...
Transformers and CRTs (generally implies flybacks) are found in metal enclosures all the time. I wouldn't think it would be a problem; the vast majority of the flux you care about is going to be in the flyback's metal core. Now, if you were talking big air-core reactors, then you might have to start worrying about induction-heating your PC case.
Of course, putting anything HV in a metal box means there are a lot more places the HV *could* go besides where you intended
Regards,
Aaron, N7OE
Insulation is not a big problem, output voltage is only about 15kv. I will remove the 230V output plug, cover the hole with some plastic, dig a hole in the centre of the plastic and thread the HV wire through it.Transformers and CRTs (generally implies flybacks) are found in metal enclosures all the time. I wouldn't think it would be a problem; the vast majority of the flux you care about is going to be in the flyback's metal core. Now, if you were talking big air-core reactors, then you might have to start worrying about induction-heating your PC case.
Of course, putting anything HV in a metal box means there are a lot more places the HV *could* go besides where you intended
Regards,
Aaron, N7OE
Yes, some flybacks in crt's are in metal enclosure, but there they do not work at too high powers, I guess around 50w for a standard flyback. My flyback is going to operate over 300w so I was wondering that if I screw it to the metal case (so the core will be really close to the case), the flyback could inductive heat the case and decrease performance.
Re: Flyback Driver inside a PC PSU box
Steve Ward, Wed Jan 31 2007, 05:25PM
The only possible location for induction to surrounding materials is at the gap in the core. But, the gap is usually so tiny, that the flux doesnt extend out from the core much at all. Otherwise, 99% of the magnetic flux is going to be contained within the ferrite, no worries about induction heating the case.
I dont suspect your flyback will last long at 300W, though.
Steve Ward, Wed Jan 31 2007, 05:25PM
My flyback is going to operate over 300w so I was wondering that if I screw it to the metal case (so the core will be really close to the case), the flyback could inductive heat the case and decrease performance.
The only possible location for induction to surrounding materials is at the gap in the core. But, the gap is usually so tiny, that the flux doesnt extend out from the core much at all. Otherwise, 99% of the magnetic flux is going to be contained within the ferrite, no worries about induction heating the case.
I dont suspect your flyback will last long at 300W, though.
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Wed Jan 31 2007, 06:12PM
I was very lucky to get such a "killer" flyback, it gets just little warm after operating a Jacob's ladder for few minutes at full power
(300w is only at max. arc lenght, so I guess the average power is more like 200w)
Of course when I get it finished, I'll post some scary arc pictures
Dr. Dark Current, Wed Jan 31 2007, 06:12PM
Steve Ward wrote ...
The only possible location for induction to surrounding materials is at the gap in the core. But, the gap is usually so tiny, that the flux doesnt extend out from the core much at all. Otherwise, 99% of the magnetic flux is going to be contained within the ferrite, no worries about induction heating the case.
I dont suspect your flyback will last long at 300W, though.
In my design the core does not use a gap, so I guess it is fine then ;)My flyback is going to operate over 300w so I was wondering that if I screw it to the metal case (so the core will be really close to the case), the flyback could inductive heat the case and decrease performance.
The only possible location for induction to surrounding materials is at the gap in the core. But, the gap is usually so tiny, that the flux doesnt extend out from the core much at all. Otherwise, 99% of the magnetic flux is going to be contained within the ferrite, no worries about induction heating the case.
I dont suspect your flyback will last long at 300W, though.
I was very lucky to get such a "killer" flyback, it gets just little warm after operating a Jacob's ladder for few minutes at full power
(300w is only at max. arc lenght, so I guess the average power is more like 200w)Of course when I get it finished, I'll post some scary arc pictures
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Sun Feb 04 2007, 12:41PM
Oh well, my flyback is now ruined
. A nice yellow light is shining from the inside of the secondary. I had the driver nearly finished, built into the pc psu case, when the flyback arced inside the secondary. I have one (different) secondary left that I will try, but I think it will make nowhere as nice arcs as the one that just burned.
edit> the new secondary is not as bad as I expected, the arcs are a little shorter, but "idle" current was decreased as well as driver heating. I will post pics after the driver is finished.
Dr. Dark Current, Sun Feb 04 2007, 12:41PM
Oh well, my flyback is now ruined
. A nice yellow light is shining from the inside of the secondary. I had the driver nearly finished, built into the pc psu case, when the flyback arced inside the secondary. I have one (different) secondary left that I will try, but I think it will make nowhere as nice arcs as the one that just burned.edit> the new secondary is not as bad as I expected, the arcs are a little shorter, but "idle" current was decreased as well as driver heating. I will post pics after the driver is finished.
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Mon Feb 05 2007, 04:22PM
It is done the flyback is really AMAZING find, puts out scary flaming arcs, almost like a small mot 
,but it gets just little warm after minutes of abuse.
pics
the box of death
:
inside
mot-like arcs:
that arc is like 12cm long
Dr. Dark Current, Mon Feb 05 2007, 04:22PM
It is done
the flyback is really AMAZING find, puts out scary flaming arcs, almost like a small mot ,but it gets just little warm after minutes of abuse.pics
the box of death
:
inside
mot-like arcs:
that arc is like 12cm long
Re: Flyback Driver inside a PC PSU box
..., Tue Feb 06 2007, 02:16AM
Meh, you need to switch over to a mazzilli driver and my homewound flyback...
I just need to solve that little problem that the fets release their m4g1c 5m0k3 at 120v instead of at 200v (so I can run it off fullwave rectified mains)
It would fit in a computer psu case, but I would have to use oil arround the flyback/doubler since sparks can start at ~2" (tracking)
But making it small and self conatined like that is pretty sweet!
..., Tue Feb 06 2007, 02:16AM
Meh, you need to switch over to a mazzilli driver and my homewound flyback...
I just need to solve that little problem that the fets release their m4g1c 5m0k3 at 120v instead of at 200v (so I can run it off fullwave rectified mains)
It would fit in a computer psu case, but I would have to use oil arround the flyback/doubler since sparks can start at ~2" (tracking)But making it small and self conatined like that is pretty sweet!
Re: Flyback Driver inside a PC PSU box
ragnar, Tue Feb 06 2007, 04:26AM
That's the way! =-D
ragnar, Tue Feb 06 2007, 04:26AM
That's the way! =-D
Re: Flyback Driver inside a PC PSU box
TheMerovingian, Tue Feb 06 2007, 10:10AM
I am a bit warned by safety. You should use a ceramic insulator to hold the hv wire. If you accidentally brush your hand on that thing, touching the metal case, you will get a nasty burn on your hand .
TheMerovingian, Tue Feb 06 2007, 10:10AM
I am a bit warned by safety. You should use a ceramic insulator to hold the hv wire. If you accidentally brush your hand on that thing, touching the metal case, you will get a nasty burn on your hand .
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Tue Feb 06 2007, 03:31PM
hmm, those are really scary arcs bp
, I think my flyback could also do such arcs but i want it to last and not melt after 20 seconds (i can run it for hours just fine)
And theres aproblem with the "zvs" driver that the primary gets nasty hot even if you use thick wire and if you wand it to run directly from mains you need xpensive hv fets. (my halfbridge overcomes all these problems i think )
btw. BP, how much power did you get in that arc? My flyback does not make very high voltage ,so it takes around 350w to stretch the arc to ~12cm, butthe arc is very hot (i calculated about 70ma of current)
Dr. Dark Current, Tue Feb 06 2007, 03:31PM
hmm, those are really scary arcs bp
, I think my flyback could also do such arcs but i want it to last and not melt after 20 seconds (i can run it for hours just fine)And theres aproblem with the "zvs" driver that the primary gets nasty hot even if you use thick wire and if you wand it to run directly from mains you need xpensive hv fets. (my halfbridge overcomes all these problems i think
)btw. BP, how much power did you get in that arc? My flyback does not make very high voltage ,so it takes around 350w to stretch the arc to ~12cm, butthe arc is very hot (i calculated about 70ma of current)
Re: Flyback Driver inside a PC PSU box
Marko, Tue Feb 06 2007, 03:45PM
I think blackplasma used 4 flybacks..in parallel, there?
Only thing I trust is a 2 meter long chicken stick.. I wouldm't be anywhere near the box while it's running anyways...
Marko, Tue Feb 06 2007, 03:45PM
I think blackplasma used 4 flybacks..in parallel, there?
I am a bit warned by safety. You should use a ceramic insulator to hold the hv wire. If you accidentally brush your hand on that thing, touching the metal case, you will get a nasty burn on your hand .
Only thing I trust is a 2 meter long chicken stick.. I wouldm't be anywhere near the box while it's running anyways...
Re: Flyback Driver inside a PC PSU box
uzzors2k, Tue Feb 06 2007, 07:41PM
Nice job jmartis. What kind of driver is it, just a tl494->halfbridge thing? How many turns are you using on the flyback primary?
uzzors2k, Tue Feb 06 2007, 07:41PM
Nice job jmartis. What kind of driver is it, just a tl494->halfbridge thing? How many turns are you using on the flyback primary?
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Tue Feb 06 2007, 08:31PM
My fuse kept blowing (the caps acted as a short when empty) so I included a charging circuit that consists of a charging resistor and a relay delay ( ) circuit, that shorts the resistor after the caps have charged. I think it works quite well.
Edit> I just found that the metal case around the flyback secondary is heating a bit, what is causing this? I hope it doesnt reduce performance too much...
Dr. Dark Current, Tue Feb 06 2007, 08:31PM
uzzors wrote ...
Nice job jmartis. What kind of driver is it, just a tl494->halfbridge thing? How many turns are you using on the flyback primary?
Hi uzzors, thanks, it uses ir2153 halfbridge driver ic to drive irf740 halfbridge (no gdt's requied), operating frequency ~30k. There are 30 turns of pvc-insulated wire on the primary.Nice job jmartis. What kind of driver is it, just a tl494->halfbridge thing? How many turns are you using on the flyback primary?
My fuse kept blowing (the caps acted as a short when empty) so I included a charging circuit that consists of a charging resistor and a relay delay (
) circuit, that shorts the resistor after the caps have charged. I think it works quite well.Edit> I just found that the metal case around the flyback secondary is heating a bit, what is causing this? I hope it doesnt reduce performance too much...
Re: Flyback Driver inside a PC PSU box
Steve Conner, Tue Feb 06 2007, 10:26PM
Good work jmartis! Most hobbyists seem to have real trouble getting those IR half-bridge driver ICs to work well.
Steve Conner, Tue Feb 06 2007, 10:26PM
Good work jmartis! Most hobbyists seem to have real trouble getting those IR half-bridge driver ICs to work well.
Re: Flyback Driver inside a PC PSU box
Marko, Wed Feb 07 2007, 09:24AM
You can use an NTC thermistor (from ATX supply, same purpose) to limit the inruch current to caps.
It's just connected series with AC input.
Relay circuit is surely better, but not as cost-effective solution.
Marko, Wed Feb 07 2007, 09:24AM
My fuse kept blowing (the caps acted as a short when empty) so I included a charging circuit that consists of a charging resistor and a relay delay ( ) circuit, that shorts the resistor after the caps have charged. I think it works quite well.
You can use an NTC thermistor (from ATX supply, same purpose) to limit the inruch current to caps.
It's just connected series with AC input.
Relay circuit is surely better, but not as cost-effective solution.
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Wed Feb 07 2007, 02:04PM
Dr. Dark Current, Wed Feb 07 2007, 02:04PM
Steve Cønner wrote ...
Good work jmartis! Most hobbyists seem to have real trouble getting those IR half-bridge driver ICs to work well.
Thanks. No trouble here, i've made a few fbt drivers with this ic before, and everytime it worked on first light.Good work jmartis! Most hobbyists seem to have real trouble getting those IR half-bridge driver ICs to work well.
Firkragg wrote ...
You can use an NTC thermistor (from ATX supply, same purpose) to limit the inruch current to caps.
It's just connected series with AC input.
Yes I tried this, but after the thermistor heats up and you relatively fast turn it off-on, it can also blow the fuse.You can use an NTC thermistor (from ATX supply, same purpose) to limit the inruch current to caps.
It's just connected series with AC input.
Re: Flyback Driver inside a PC PSU box
uzzors2k, Wed Feb 07 2007, 06:10PM
How do you guys get such massive arcs? Special flybacks? I tried with 24 primary turns directly off mains, but the arcs are still only around 6 cm.
uzzors2k, Wed Feb 07 2007, 06:10PM
How do you guys get such massive arcs? Special flybacks? I tried with 24 primary turns directly off mains, but the arcs are still only around 6 cm.
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Wed Feb 07 2007, 07:17PM
Dr. Dark Current, Wed Feb 07 2007, 07:17PM
uzzors wrote ...
How do you guys get such massive arcs? Special flybacks? I tried with 24 primary turns directly off mains, but the arcs are still only around 6 cm.
My arcs are about 12cm when stredched vertically and maybe 7cm horizontally, how did you measure it? No special flyback, just old AC one, that can put out more current so that maybe explains why the arcs can be stretched further, but I'm not really sure How do you guys get such massive arcs? Special flybacks? I tried with 24 primary turns directly off mains, but the arcs are still only around 6 cm.
Re: Flyback Driver inside a PC PSU box
uzzors2k, Wed Feb 07 2007, 08:23PM
I estimated the length by usig the ruler in the picture. A vertical arc was all it took, I can pull them to about 10 cm now, so I guess our drivers are working just as good. After all, we're both using mains driven half-bridges. Do you have an extra flyback? Maybe we should try to beat the ZVS guys.
uzzors2k, Wed Feb 07 2007, 08:23PM
I estimated the length by usig the ruler in the picture. A vertical arc was all it took, I can pull them to about 10 cm now, so I guess our drivers are working just as good. After all, we're both using mains driven half-bridges. Do you have an extra flyback? Maybe we should try to beat the ZVS guys.
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Wed Feb 07 2007, 09:11PM
I have two old identical flybacks, maybe I will try to run them in parallel for maximum arc lenght, but the cores are somewhat crappy so I don't know how much abuse they will take I can also try "dual double flyback" since I have four similar secondaries - I will put two on each core. If I can get some monster arcs I will start a new thread 
Dr. Dark Current, Wed Feb 07 2007, 09:11PM
I have two old identical flybacks, maybe I will try to run them in parallel for maximum arc lenght, but the cores are somewhat crappy so I don't know how much abuse they will take
I can also try "dual double flyback" since I have four similar secondaries - I will put two on each core. If I can get some monster arcs I will start a new thread Re: Flyback Driver inside a PC PSU box
ragnar, Wed Feb 07 2007, 10:15PM
I beat you to it, by the way :P
ragnar, Wed Feb 07 2007, 10:15PM
I beat you to it, by the way :P
Re: Flyback Driver inside a PC PSU box
uzzors2k, Thu Feb 08 2007, 03:54PM
I've never been able to understand how you got that primary wound.
uzzors2k, Thu Feb 08 2007, 03:54PM
I've never been able to understand how you got that primary wound.
Re: Flyback Driver inside a PC PSU box
Dr. Dark Current, Thu Feb 08 2007, 06:23PM
Oops, today I had an accident with my flyback driver I wanted to make fun from frying an old computer circuit board. I turned the driver on - and immediately an arc jumped *inside* the PC PSU box! It had jumped over 40mm which is over 40kv. Probably the circuit board connected to hv out dropped the flyback's resonant frequency near the running frequency resulting in huge voltage boost. Now I'm afraid of connecting anything big to the output
Dr. Dark Current, Thu Feb 08 2007, 06:23PM
Oops, today I had an accident with my flyback driver
I wanted to make fun from frying an old computer circuit board. I turned the driver on - and immediately an arc jumped *inside* the PC PSU box! It had jumped over 40mm which is over 40kv. Probably the circuit board connected to hv out dropped the flyback's resonant frequency near the running frequency resulting in huge voltage boost. Now I'm afraid of connecting anything big to the output Re: Flyback Driver inside a PC PSU box
Colin 99, Sun Feb 11 2007, 07:19PM
I build a mazzilla driver too. I found you can increase the output by using a larger resonant capacitor, I'm presently using 2uF pulse rated cap. Also a capacitor across the flyback primary center tap to ground (battery neg), 0.68uF seems to help and large capacitors across the power supply input. I'm using three 12v batteries in series instead of a AC powered supply, so I didn't cap caps across the ps when I started. Also high voltage zeners, I'm using 15 volt ones. I can draw upto 13 amps at 36 volts i/p with this setup at maximum arc length
. I have it connected to a small jaccobs ladder, 4 inchs at the top and it climbs a couple of inches above that with a thick orange arc, I don't I have pictures yet. I guess that's next.
What voltage are you guys running your flyback driver at and what modifications did you have to make to the mazzilla driver for that.
Shaun
Colin 99, Sun Feb 11 2007, 07:19PM
I build a mazzilla driver too. I found you can increase the output by using a larger resonant capacitor, I'm presently using 2uF pulse rated cap. Also a capacitor across the flyback primary center tap to ground (battery neg), 0.68uF seems to help and large capacitors across the power supply input. I'm using three 12v batteries in series instead of a AC powered supply, so I didn't cap caps across the ps when I started. Also high voltage zeners, I'm using 15 volt ones. I can draw upto 13 amps at 36 volts i/p with this setup at maximum arc length
. I have it connected to a small jaccobs ladder, 4 inchs at the top and it climbs a couple of inches above that with a thick orange arc, I don't I have pictures yet. I guess that's next. What voltage are you guys running your flyback driver at and what modifications did you have to make to the mazzilla driver for that.
Shaun
Re: Flyback Driver inside a PC PSU box
..., Sun Feb 11 2007, 08:18PM
before we get too far off topic, if you want to talk about matt or my flybacks, post in our threads please!
mine is here. Matt (BlackPlasma) also has one on the old 4hv, but I am sure he would be happy to make a new one for you to talk about his work
..., Sun Feb 11 2007, 08:18PM
before we get too far off topic, if you want to talk about matt or my flybacks, post in our threads please!
mine is here. Matt (BlackPlasma) also has one on the old 4hv, but I am sure he would be happy to make a new one for you to talk about his work
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