Looks great. You have to experiment with the number of turns and the capacitance. I would start with 5+5. What kind of output do you get?

I tried to measure the voltage like you but I don't know why it doesn't work. But with 5+5 turns and a 16volts input the arcs in the secondary of the HF transformer starts at let's say 5 or 6mm so I think it is 5 or 6kv peak

Quote

And another questión. I´m going to use one 24V power supply. I have put a 220ohm resistor in point A to use the 24Volts directly. And to power the ZVS driver, I put in the 24V power supply a DC-DC converter to vary the output. There is no problem taking the current for the gates and to power de ZVS from the same power supply right?

I have instaled a relay that allow to power the ZVS only when the gates are already with the 24volts to be safe.

Yes, that should work well.  Presuming the existing 470ohm gate pull-up resistors are rated for 2 watts as listed in schematic, they will handle 24V directly.  No need for 220-ohm resistor to reduce power.  As a bonus, with 24V directly to gate resistors the FETs will switch faster so dissipate a bit less power.  Removing 220-ohm resistor also increases startup oscillation amplitude before relay closes, making startup even a bit more reliable.

Thank for your answer

I added the 220 ohm resistor because de 470 ohm resistor, despite being 2watts get too hot and they where close to the MOSFETs in the PCB.

Since I'm going to enclose everything, I'm going to remove the 470 ohm resistor from the PCB and put th near the fan what pull the air from.the enclosure and they will get cooler

Look further down in the comments of the link to my CW multiplier that I supplied. I describe the method that I used to measure the HV output of the flyback transformer using a full-wave bridge rectifier, smoothing capacitor, and a COTS HV DC voltmeter.

Even to just measure the transformer output you make a neat and clean set up!!

Thanks for your answer. My concern is about the reduction of the voltage. I see you are using a HV probe right? I made a DIY probe with 10x 26Mohm resistor for a 1000:1 ratio. So can I use it with a 2nF capacitor to obtain the measurement of the peak voltage?

Yes. You want at least 10 volts at point "A" from the DC power supply before you switch the power to the ZVS driver. I use a minimum of 12 volts just to be safe.

Thanks for your answer.

Yess I learnt that in this forum some time ago asking about a ZVS for an induction heater.

And another question. About measuring the output of the HF transformer. Could I do it using a bridge rectifier (HV diodes), capacitor to filter and a voltage divider using HV resistors? Let's say 260Megaohms. What should be the value of tha capacitor?

I use a basic needle voltmeter because my DMMs are cheap and got crazy measuring these things so I think it is a good idea to use a capacitor to know the peak value of the output. And should I use in the output of the transformer (I have some HV caps if around 10nf) or I can do it in the output of the voltage divider which would allow me to use a regular capacitor ?

Thank you for your answer and the link, it is very useful.

My idea it is to put 10 stages to keep at minimum the voltage input.
I'm going to run a high frequency 300watts transformer with a ZVS. The gates are powered by an independent power supply and the rest of the circuit with a variable power supply, so I can vary the output. Is that a good idea? I mean in terms of voltage and current output and safety of the components.

I need to check the voltages at the secondary of the HF transformer, but I think with just 1 or 2 volts at the primary I can get around 1 or 2 kV at the secondary, so starting with around 40kV at the CW and more

Thank you

Flyback transformers are special in having an air gapped core, which is utilized by the driving method Flyback converter topology.

So a flyback transformer is just a air gapped transformer. It is the driving method where energy is stored in the core in the first half cycle, switch turns off and energy is transferred to the secondary winding in the second half cycle.

The term flyback comes from Cathode ray tubes (old TVs and monitors) where the abrubt saw tooth like output, got the beam in the cannon to flyback to draw the next line on the monitor.

In high voltage world, we abuse the shit out of them with all other kinds of drive modes than flyback We feed them with ZVS, single switch, half-bridge or full-bridge inverters to get the highest possible voltage output, often leading to a premature death of the transformer.

To drive it continuesly, the air gap should be removed, as the half cycle energy storage is no longer being used. On the other side, core saturation will happen much faster.

Thank you!!

Now is clear!

Thank you

Oh I didn´t know that. thabks for your answer.

Hello.

I´m making a crofton walton generator and for testing I´m using paraffin oil. It is a very good insulator, but is a mess. So, for the final set up mi idea is to por melted paraffin wax from candles. Of course regular white candles. No aroma, no color. Once solidified, will it be as good insulator as paraffin oil?

It melts around 50ºC so shoudn't damage the diodes nor the caps right?

Thank you

Best regards

Hello.

I want to use a crofton walton with a small AC flyback. I have run it with a ZVS. The problem is I need at least 12 volts to run the ZVS because below that voltage I have read I can break it. And at this voltage the output of the flyback is too high and I´m going to need very big components for the CW or put some of the in series.

I also want to be able to vary the voltage. I have tried a 555 based oscillator  with a IRPF450 at 20KHz and it works great. For example at only 3 volts I get with 4 stages 3-4 cm sparks. And at 12 V almost 10 cm sparks, enought for me. What do you think of this set up?

I ask that because everywhere I see people using ZVS. The other question is that I´m using the 555 oscillator because is one what I  biult and is variable, for experiments, but since I want to run the flyback always at 20khz, I think I could built a simpler one, because I think the 555 could be sensible to the "things" happening in the transformer.

Thank you

Best regards