ZVS flyback driver SSTC
ZakWolf, Sat Nov 06 2010, 08:06AMI saw an old post where someone used a soda bottle and a ZVS flyback driver to make a SSTC.
Is this possible? If so how?
soda bottle tesla coil
Re: ZVS flyback driver SSTC
Sulaiman, Sun Nov 07 2010, 11:18AM
An sstc secondary needs to be driven with either
- a magnetic field
OR
- a voltage/current injected into the bottom end
at its resonant frequency.
SO you could use a zvs where the resonant inductor is
- a 'normal' sstc primary
OR
- the primary of a transformer with a high voltage secondary connected to the resonator base.
Which is best? ..... I prefer the 'normal' sstc primary approach as it's more 'efficient'
All you need is 2,4,6,.... primary turns centre-tapped.
(plus resonant capacitor, 2 transistors,diodes & resistors and the series/dc inductor)
Sulaiman, Sun Nov 07 2010, 11:18AM
An sstc secondary needs to be driven with either
- a magnetic field
OR
- a voltage/current injected into the bottom end
at its resonant frequency.
SO you could use a zvs where the resonant inductor is
- a 'normal' sstc primary
OR
- the primary of a transformer with a high voltage secondary connected to the resonator base.
Which is best? ..... I prefer the 'normal' sstc primary approach as it's more 'efficient'
All you need is 2,4,6,.... primary turns centre-tapped.
(plus resonant capacitor, 2 transistors,diodes & resistors and the series/dc inductor)
Re: ZVS flyback driver SSTC
Arcstarter, Sun Nov 07 2010, 07:15PM
Arcstarter, Sun Nov 07 2010, 07:15PM
LittleVenture wrote ...
I saw an old post where someone used a soda bottle and a ZVS flyback driver to make a SSTC.
Is this possible? If so how?
soda bottle tesla coil
Not only can you use the driver, but it can be made to work incredibly well. I believe it was Vasil from this forum that made a sstc (actually, it is a dual resonant sstc, but parallel resonance instead of series resonance) with the same circuit and something like 24" sparks and impressively small heatsinks.I saw an old post where someone used a soda bottle and a ZVS flyback driver to make a SSTC.
Is this possible? If so how?
soda bottle tesla coil
Re: ZVS flyback driver SSTC
ZakWolf, Mon Nov 08 2010, 02:58AM
so how many turns do i need for the primary?
ZakWolf, Mon Nov 08 2010, 02:58AM
so how many turns do i need for the primary?
Re: ZVS flyback driver SSTC
Arcstarter, Mon Nov 08 2010, 04:49AM
Arcstarter, Mon Nov 08 2010, 04:49AM
LittleVenture wrote ...
so how many turns do i need for the primary?
Think about how the driver itself works... You'll need to make the primary and tank cap resonate at the frequency of your secondary. Use a sgtc tank circuit calculator to find what inductance and capacitance makes what frequency. About 3+3 would be a good place to start.so how many turns do i need for the primary?
Re: ZVS flyback driver SSTC
ZakWolf, Mon Nov 08 2010, 05:30PM
I wound a 3+3 primary and hooked that to the driver i turned it on and didnt get anything. Do i need to use some sort of capacitor or am i doing something wrong?
ZakWolf, Mon Nov 08 2010, 05:30PM
I wound a 3+3 primary and hooked that to the driver i turned it on and didnt get anything. Do i need to use some sort of capacitor or am i doing something wrong?
Re: ZVS flyback driver SSTC
Matt Edwards, Tue Nov 16 2010, 07:16PM
When I attempted a similar project I used a 30kv 1000pf cap and spark gap before the primary of the coil. I also center tapped each turn on the primary for tuning. It was setup in a similar fashion to a SGTC tank between the flyback and primary. If you do what was suggested by arcstarter and adjust the primary resonance to match the secondary you should be good to go. But I have only seen a small handful of flyback driven coils that produced decent results.
Matt Edwards, Tue Nov 16 2010, 07:16PM
When I attempted a similar project I used a 30kv 1000pf cap and spark gap before the primary of the coil. I also center tapped each turn on the primary for tuning. It was setup in a similar fashion to a SGTC tank between the flyback and primary. If you do what was suggested by arcstarter and adjust the primary resonance to match the secondary you should be good to go. But I have only seen a small handful of flyback driven coils that produced decent results.
Re: ZVS flyback driver SSTC
Arcstarter, Tue Nov 16 2010, 08:44PM
What do you mean by "Do i need some sort of capacitor"? Before you use a Tesla coil setup, just try it on a flyback transformer with a tank cap of around .68uf or whatever you want to use.
The capacitor for the sstc will be a much lower capacitance to shift the resonant frequency of the tank circuit way up, to match the secondary's resonant frequency. In that respect, it is a dual resonant sstc, but it is parallel resonance and will give sparks like a typical sstc.
But because of this, there is no secondary feedback, so the primary resonance will have to be adjusted according to secondary loading. The primary resonance may shift a bit when the secondary is loaded due to the coupling, but im not sure how far from resonance it will get.
The tank capacitor will have to be accurate within pf range to insure you get the right freq. Primary inductance can also be tweaked to get the right resonant freq. Look at Richie Burnett's graph of the resonance of a Tesla secondary. As you can see, just a tiny % away from resonance makes a big difference in the output voltage. The page explaining this graph is here:
Arcstarter, Tue Nov 16 2010, 08:44PM
Oidium45 wrote ...
When I attempted a similar project I used a 30kv 1000pf cap and spark gap before the primary of the coil. I also center tapped each turn on the primary for tuning. It was setup in a similar fashion to a SGTC tank between the flyback and primary. If you do what was suggested by arcstarter and adjust the primary resonance to match the secondary you should be good to go. But I have only seen a small handful of flyback driven coils that produced decent results.
He is not talking about a SGTC, he is talking about a sstc with the ZVS driver directly driving the primary. It works, and produces fantastic results due to the low switching loss nature of the driver, if made well.When I attempted a similar project I used a 30kv 1000pf cap and spark gap before the primary of the coil. I also center tapped each turn on the primary for tuning. It was setup in a similar fashion to a SGTC tank between the flyback and primary. If you do what was suggested by arcstarter and adjust the primary resonance to match the secondary you should be good to go. But I have only seen a small handful of flyback driven coils that produced decent results.
What do you mean by "Do i need some sort of capacitor"? Before you use a Tesla coil setup, just try it on a flyback transformer with a tank cap of around .68uf or whatever you want to use.
The capacitor for the sstc will be a much lower capacitance to shift the resonant frequency of the tank circuit way up, to match the secondary's resonant frequency. In that respect, it is a dual resonant sstc, but it is parallel resonance and will give sparks like a typical sstc.
But because of this, there is no secondary feedback, so the primary resonance will have to be adjusted according to secondary loading. The primary resonance may shift a bit when the secondary is loaded due to the coupling, but im not sure how far from resonance it will get.
The tank capacitor will have to be accurate within pf range to insure you get the right freq. Primary inductance can also be tweaked to get the right resonant freq. Look at Richie Burnett's graph of the resonance of a Tesla secondary.
As you can see, just a tiny % away from resonance makes a big difference in the output voltage. The page explaining this graph is here: Re: ZVS flyback driver SSTC
Matt Edwards, Wed Nov 17 2010, 12:54AM
My mistake. I should have read the thread more thoroughly. If you get your coil operational you should post some photographs, schematics, etc... As I said before, I tried something similar a while back but couldn't find info online so I ended up going for a spark gap setup which performed poorly.
Matt Edwards, Wed Nov 17 2010, 12:54AM
My mistake. I should have read the thread more thoroughly. If you get your coil operational you should post some photographs, schematics, etc... As I said before, I tried something similar a while back but couldn't find info online so I ended up going for a spark gap setup which performed poorly.
Re: ZVS flyback driver SSTC
ZakWolf, Wed Nov 17 2010, 06:57AM
I am really confused... My ZVS flyback driver works awesome for my flybacks. My ZVS flyback driver has 3 out puts of course i was wondering why i need a capaictor i thought it would be just like a big flyback basically. I just wound 3+3 around the base of the secondary and nothing happened i will try some more and if i get it working i will post info
Could someone make a simple schematic please thanks
ZakWolf, Wed Nov 17 2010, 06:57AM
I am really confused... My ZVS flyback driver works awesome for my flybacks. My ZVS flyback driver has 3 out puts of course i was wondering why i need a capaictor i thought it would be just like a big flyback basically. I just wound 3+3 around the base of the secondary and nothing happened i will try some more and if i get it working i will post info
Could someone make a simple schematic please thanks
Re: ZVS flyback driver SSTC
Matt Edwards, Wed Nov 17 2010, 02:18PM
What are you using for the power supply?
Matt Edwards, Wed Nov 17 2010, 02:18PM
What are you using for the power supply?
Re: ZVS flyback driver SSTC
Arcstarter, Wed Nov 17 2010, 08:37PM
I know that Jovicakluk on youtube made a ZVS driver running with 15v drive a secondary WAY off resonance and still got discharge, somehow. I guess the secondary was running like a transformer rather than a Tesla coil. His tank cap was .1uf so i know the frequency was way lower than the small secondary with no topload.
Arcstarter, Wed Nov 17 2010, 08:37PM
LittleVenture wrote ...
I am really confused... My ZVS flyback driver works awesome for my flybacks. My ZVS flyback driver has 3 out puts of course i was wondering why i need a capaictor i thought it would be just like a big flyback basically. I just wound 3+3 around the base of the secondary and nothing happened i will try some more and if i get it working i will post info
Could someone make a simple schematic please thanks
Follow the ZVS driver schematic... All ZVS flyback drivers require a tank cap, so why would you not need a capacitor? Remember what i said, if it is not in tune, you wont see an output because it is too off resonance. Guessing values won't work well. Also, you will need more than 12v to make any visible discharge most likely. I am really confused... My ZVS flyback driver works awesome for my flybacks. My ZVS flyback driver has 3 out puts of course i was wondering why i need a capaictor i thought it would be just like a big flyback basically. I just wound 3+3 around the base of the secondary and nothing happened i will try some more and if i get it working i will post info
Could someone make a simple schematic please thanks
I know that Jovicakluk on youtube made a ZVS driver running with 15v drive a secondary WAY off resonance and still got discharge, somehow. I guess the secondary was running like a transformer rather than a Tesla coil. His tank cap was .1uf so i know the frequency was way lower than the small secondary with no topload.
Re: ZVS flyback driver SSTC
dillon, Sun May 17 2015, 05:02PM
i think zvs flyback driver topolgy is great for a tesla coil. i have 500 nanohenery+ 500 nanohenery primary with a 50 nano farad capacitor in parallel. I get 23" sword sparks from mine.
dillon, Sun May 17 2015, 05:02PM
i think zvs flyback driver topolgy is great for a tesla coil. i have 500 nanohenery+ 500 nanohenery primary with a 50 nano farad capacitor in parallel. I get 23" sword sparks from mine.
Re: ZVS flyback driver SSTC
Wolfram, Sun May 17 2015, 06:21PM
Very nice result. Do you have any more information on your setup? Is it half wave rectified, and what voltage are you running at?
Wolfram, Sun May 17 2015, 06:21PM
Very nice result. Do you have any more information on your setup? Is it half wave rectified, and what voltage are you running at?
Re: ZVS flyback driver SSTC
dillon, Mon May 18 2015, 01:46PM
running straight off the wall,and yes it is half wave rectified.the mosfet is FQA19N60. and i have a ltspice file at
dillon, Mon May 18 2015, 01:46PM
running straight off the wall,and yes it is half wave rectified.the mosfet is FQA19N60. and i have a ltspice file at
Re: ZVS flyback driver SSTC
Eleccentric, Tue May 19 2015, 01:13AM
That is certainly the simplest schematic I have ever seen for such a well-performing coil. What did you use to generate the negative pulse on one of the gates at start-up?
Eleccentric, Tue May 19 2015, 01:13AM
That is certainly the simplest schematic I have ever seen for such a well-performing coil. What did you use to generate the negative pulse on one of the gates at start-up?
Re: ZVS flyback driver SSTC
dillon, Wed May 20 2015, 03:38PM
the startup pluse is just to get ltspice to self oscillate. In reality it oscillates by its self. the mosfets are paralleled with 3 sets, and they are frozen in the freezer before operation. other than that the circuit is 100% accurate. even the coupleing. It does not work well close coupleing. The secondary is 3.5 " and the primary is 6" in diameter.
dillon, Wed May 20 2015, 03:38PM
the startup pluse is just to get ltspice to self oscillate. In reality it oscillates by its self. the mosfets are paralleled with 3 sets, and they are frozen in the freezer before operation. other than that the circuit is 100% accurate. even the coupleing. It does not work well close coupleing. The secondary is 3.5 " and the primary is 6" in diameter.
Re: ZVS flyback driver SSTC
Eleccentric, Wed May 20 2015, 04:47PM
*hearty laugh* You freeze the mosfets before running? How long are your run times before needing a refreeze?
The LTSpice simulation oscillates on its own without the startup pulse, but takes a few milliseconds to start, during which time massive current passes through the fets. Simulating using a more realistic mosfet negates the utility of the pulse - even with it things still take a few milliseconds to run properly.
I'm not surprised you need paralleled devices - the simulation predicts much larger currents than single FQA19N60s could handle.
I have a stack of C2M0080120D fets.. ..I imagine they might work well if I decide to cook up a version of this thing over the weekend.
Eleccentric, Wed May 20 2015, 04:47PM
*hearty laugh* You freeze the mosfets before running? How long are your run times before needing a refreeze?
The LTSpice simulation oscillates on its own without the startup pulse, but takes a few milliseconds to start, during which time massive current passes through the fets. Simulating using a more realistic mosfet negates the utility of the pulse - even with it things still take a few milliseconds to run properly.
I'm not surprised you need paralleled devices - the simulation predicts much larger currents than single FQA19N60s could handle.
I have a stack of C2M0080120D fets.. ..I imagine they might work well if I decide to cook up a version of this thing over the weekend.
Re: ZVS flyback driver SSTC
dillon, Wed May 20 2015, 05:15PM
it's funny the mosfet never heat up, but I figure the junction temperature is even though the case does not. I can run straight for about 7 seconds , then pause for about 15 seconds and repeat up to about 5 minutes. When paralleling the mosfets you will need about 6-8" of wire length separating each mosfet to the resonant capacitor, or else parasitic oscillations will destroy each mosfets immediately. and your mosfets will need an output capacitance lower than 500 pf , because the primary coil inductance is so low. Oh, I forgot the ballast resistor is at 1.6 ohms in for that picture
dillon, Wed May 20 2015, 05:15PM
it's funny the mosfet never heat up, but I figure the junction temperature is even though the case does not. I can run straight for about 7 seconds , then pause for about 15 seconds and repeat up to about 5 minutes. When paralleling the mosfets you will need about 6-8" of wire length separating each mosfet to the resonant capacitor, or else parasitic oscillations will destroy each mosfets immediately. and your mosfets will need an output capacitance lower than 500 pf , because the primary coil inductance is so low. Oh, I forgot the ballast resistor is at 1.6 ohms in for that picture
Re: ZVS flyback driver SSTC
Eleccentric, Wed May 20 2015, 11:16PM
Interestingly, LTSpice doesn't show parasitic oscillation with paralleled devices, but if I add 150nH in series with each drain, then there is terrible UHF oscillation along with voltage spikes approaching 2kV.
*spends time with the simulation*
Ah, of course. The gate turn-off diodes should run directly to the tank cap, since we want THAT oscillation to control the gate, not some local UHF crud. Is that what you did?
Eleccentric, Wed May 20 2015, 11:16PM
Interestingly, LTSpice doesn't show parasitic oscillation with paralleled devices, but if I add 150nH in series with each drain, then there is terrible UHF oscillation along with voltage spikes approaching 2kV.
*spends time with the simulation*
Ah, of course. The gate turn-off diodes should run directly to the tank cap, since we want THAT oscillation to control the gate, not some local UHF crud. Is that what you did?
Re: ZVS flyback driver SSTC
dillon, Thu May 21 2015, 12:53AM
I have the diodes directly on the mosfets. I agree the leakage inductance back emf should cause problems. I no problems when I was running only one set of mosfets. I have a theory, with 3 mosfets paralled would have 800 to 900 pico farads and if the mosfets were connect fairly close say like 2nh ,would give a resonant frequency of 125 Mhz. that would be an impedance of 1.57 ohms. But if their 6-7 " away that would be 100nh and resonate at 18 Mhz with a resonate frequency of 11 ohms which is higher than my tank impedance. This is just a guess. All I know If I hook the mosfets directly together, they blow instantly. and if I use like superfet or any fet output capacitance higher than 1000 pf it won't work. I gone through A LOT of different mosfets, these are the only ones that have ever worked. But in theory I agree with everything you said.
dillon, Thu May 21 2015, 12:53AM
I have the diodes directly on the mosfets. I agree the leakage inductance back emf should cause problems. I no problems when I was running only one set of mosfets. I have a theory, with 3 mosfets paralled would have 800 to 900 pico farads and if the mosfets were connect fairly close say like 2nh ,would give a resonant frequency of 125 Mhz. that would be an impedance of 1.57 ohms. But if their 6-7 " away that would be 100nh and resonate at 18 Mhz with a resonate frequency of 11 ohms which is higher than my tank impedance. This is just a guess. All I know If I hook the mosfets directly together, they blow instantly. and if I use like superfet or any fet output capacitance higher than 1000 pf it won't work. I gone through A LOT of different mosfets, these are the only ones that have ever worked. But in theory I agree with everything you said.
Re: ZVS flyback driver SSTC
Eleccentric, Thu May 21 2015, 09:09PM
I agree with you on those values for impedance of the leakage inductance at the resonant frequency of the output capacitance and leakage inductance. However, the impedance of the tank at those frequencies is much smaller than that of the leakage inductance, if I did my calculations correctly.
Since I've been simulating with 150nH leakage inductance, I stuck with that, but used 2nH for the "close connection" case.
For a tank of 1µH and 50nF, at 14MHz I got 0.227 ohms, and at 122MHz I got 0.0261 ohms. The impedance of the capacitor dominates.
Eleccentric, Thu May 21 2015, 09:09PM
I agree with you on those values for impedance of the leakage inductance at the resonant frequency of the output capacitance and leakage inductance. However, the impedance of the tank at those frequencies is much smaller than that of the leakage inductance, if I did my calculations correctly.
Since I've been simulating with 150nH leakage inductance, I stuck with that, but used 2nH for the "close connection" case.
For a tank of 1µH and 50nF, at 14MHz I got 0.227 ohms, and at 122MHz I got 0.0261 ohms. The impedance of the capacitor dominates.
Re: ZVS flyback driver SSTC
Whiplash, Wed Jun 03 2015, 12:30PM
some question about this: i have two server psu's 12v@90A. Can run 24v@90A or 12v@180A... what are better to start a coil with a ZVS driver? i run the ZVS direct on the primary of coil or the zvs drive a flyback thats run with a spark gap on the primary?
Whiplash, Wed Jun 03 2015, 12:30PM
some question about this: i have two server psu's 12v@90A. Can run 24v@90A or 12v@180A... what are better to start a coil with a ZVS driver? i run the ZVS direct on the primary of coil or the zvs drive a flyback thats run with a spark gap on the primary?
Re: ZVS flyback driver SSTC
dillon, Wed Jun 03 2015, 05:03PM
forget the flyback, it will saturate . I would parallel the psu's ,so not to have separate drive voltage. you will need a tank impedance of 66 milliohms. with 250nh+250nh primary coil and a 57 uf tank capacitor @42 kilohertz. if your seconardy resonance is close enough , you should rock out!
dillon, Wed Jun 03 2015, 05:03PM
forget the flyback, it will saturate . I would parallel the psu's ,so not to have separate drive voltage. you will need a tank impedance of 66 milliohms. with 250nh+250nh primary coil and a 57 uf tank capacitor @42 kilohertz. if your seconardy resonance is close enough , you should rock out!
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