Need for current from ZVS oscillator.

[Lightium]

I need more current. Any suggestions?

 

[rjenkinsgb]

The primary needs to be centre tapped and fed at that point via a commutation choke.

The choke only smooths out the changeover pulses, when both devices are on.

With two separate chokes, the current in each will be trying to vary as the transistors switch and being stabilised by the choke at the same time, so fighting each other.

Personally, I think those so-called ZVS circuits are rather nasty; they do not switch cleanly and can fail to oscillate, blowing the power devices.

A separate feedback winding with suitable bias would be far better.

 

[Lightium]

I was playing with it all night and I overlook that part about the center tap. Yes the center tapped version is better.

 

[Lightium]

The Royer oscillator has feedback.

 

[Lightium]

My royer:

 

[Lightium]

Dropping the bias resistors yields more voltage, but the current remains nearly the same.
I was able to drop the bias's to 22 ohms with out suddenly dropping voltage.

 

[Lightium]

These zvs driver circuits are a joke. I made a Jacob's ladder, but everytime the spark rises and disipates the zvs circuit locks up. Also I can blow out the spark and again the zvs locks up.

 

[Beau Schwabe]

ZVS drivers are ok if you "feed them" properly. You may want to snub L3 as it could potentially overdrive Q1 and Q2 with too much feedback voltage. Additionally you could increase R3 and R4 to something like 4.7k ... once the circuit takes off, the voltage from L3 takes over the pull-up voltage you have through R3 and R4.

 

[Nigel Goodwin]

These zvs driver circuits are a joke. I made a Jacob's ladder, but everytime the spark rises and disipates the zvs circuit locks up. Also I can blow out the spark and again the zvs locks up.

Useless crappy circuits don't work well - as you've been told many times, you need a low power oscillator, and a (suitably designed) power stage.

 

[shortbus=]

I need more current. Any suggestions?

Unless I'm totally wrong(I usually am) the only way to get more current out of something is to put more in originally, on the primary side.

 

[Lightium]

Unless I'm totally wrong(I usually am) the only way to get more current out of something is to put more in originally, on the primary side.

I've been tinkering with this circuit for more efficiency. So I had considered that as last resort.

 

[Lightium]

ZVS drivers are ok if you "feed them" properly. You may want to snub L3 as it could potentially overdrive Q1 and Q2 with too much feedback voltage. Additionally you could increase R3 and R4 to something like 4.7k ... once the circuit takes off, the voltage from L3 takes over the pull-up voltage you have through R3 and R4.

Sorry it took me awhile. I see I think that's just what it needs.

 

[Lightium]

Beau Schwaben, and so I cleaned up the square like this:

 

[Lightium]

I opted for this. What do you think?

 

[Beau Schwabe]

I would leave off C12 as it might interfere with the overall resonance of the circuit ... the reason for the diode series pair is to limit the voltage, but at the same time make sure there is enough for the B-E junction of the transistors Q1 and Q2. R8 and R10 help to prevent Q1 and Q2 from being over driven. What does the scope look like with the changes? does the circuit still stall when you break the plasma? My suspicion was that L3 would spike when the plasma was broken, thus overdriving Q1 and Q2 into a stall condition.

 

[Lightium]

I haven't build this royer yet. The original schematic I posted was the one that I blow out the spark.

 

[Lightium]

I had put in R8, R10, and C12 to filter out high frequencies.

Here's the output with filter:

 

[Lightium]

And with out the filter: