Flyback Transformer + ZVS Driver + Pulse Capacitor Inquiry

Thread Starter

Eagle111

Joined Jan 9, 2024
16
Hi everyone!

I am currently testing a flyback transformer and zvs driver to drive a spark gap around 10-15kV for research purposes and would like to add a 20kV 1.0 uF Pulse Capacitor to the output for increased power and sharper discharges.. But am unsure of what connection layout would be the most ideal and reliable. So my question is, what would be the most ideal circuit layout and should i add a resistor to the setup?

Thanks,
-Ryan
 

MisterBill2

Joined Jan 23, 2018
19,051
Given that we see no circuit at all, it is really difficult to provide any advice about the layout. I am not at all a "mind reader" person. If I see a circuit I can give advice.
 

MisterBill2

Joined Jan 23, 2018
19,051
There is not a lot of circuit detail shown in that ZVS driver portion of the circuit.

And I am really wondering about that 20kV 1.0 uF "Pulse Capacitor" that would be connected someplace. Where did you get that information, and what is the explanation for how it would change or improve the operation? Isan explanation of what it would do for you given? I will be very interested to read about what it does.

In another website that provides all sorts of "Schematics for free"there is a section on power and circuits for driving such a transformer to produce high voltage. I visited that site and verified that the circuit is still therefor free download.
 
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Thread Starter

Eagle111

Joined Jan 9, 2024
16
Hmm, yeah I wasn't sure if it would be useful to, that's why I asked here. Originally the Capacitor was for a different setup. Anyhow thanks for the advice.
 

Thread Starter

Eagle111

Joined Jan 9, 2024
16
The capacitor's purpose would be to create quick powerful discharges. However It sounds like I would need a different setup for this. Do you have any (120V to 10kV transformer) recommendations to drive a 20kv 1uF pulse capacitor with a spark gap? Thanks in advance.
 
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MisterBill2

Joined Jan 23, 2018
19,051
For a capacitor to provide a "Quick Powerful Discharge" it must first be charged by some means, and then quickly connected through a low resistance circuit path to whatever it is being discharged into.. So there are quite a few very important elements not even mentioned.
A common "flyback transformer" is not capable of that under any possible arrangement because of the higher resistance and lower power handling capacity. Certainly it can produce a SPARK. but not a powerful spark.
 

Thread Starter

Eagle111

Joined Jan 9, 2024
16
The flyback setup will be a different setup altogether from this capacitor circuit at this point. I appreciate the further insight and clarification.

I was intending to add a variable mechanical rotary switch that would switch around 500-6000 times a second. However I have been unable to find a suitable transformer or power transfer system capable of this setup without critical failure. I was planning on powering from a 120V 1000W Inverter. The transformer circuit would not only need to handle the spike discharges but also continue to function with different cycle rates. Roughly 10kV is my goal for the transformer's output.
Circuit 2.png
 
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MisterBill2

Joined Jan 23, 2018
19,051
If you are hoping to switch a DC arc on and off with a mechanical switch there will be problems in that there will be lots of arcing at the switch as well. That is certain. Once an arc is started the ionized air tends to keep conducting. AND, any metal vapor from the contacts material is a good conductor.
Can you share the purpose of this arc project with us??
 

Thread Starter

Eagle111

Joined Jan 9, 2024
16
It is a mechanical driven switch in that it is a moving part, but it will be conducting through the air itself, basically another spark gap. The purpose is scientific research and experimentation on impulse reactions. I have these other portions of design covered, including safety gear.

Really I am trying to find a commercially available transformer or circuit i could use that would work with this design. Otherwise I will make my own if need be, but could use some guidance. Do you think an isolation transformer would be suitable? Or do you have any other ideas? Thanks.
 

MisterBill2

Joined Jan 23, 2018
19,051
I have some rather bad news for the project, which is that it closely resembles the spark transmitters of a hundred plus years ago. They are no longer legal because of the very broad-bandwidth signal that they emit. Such a signal will cause disruptive interference to a large span of wireless communications, rendering them unusable during the interference time. So inn addition to violating a number of seriously enforced federal laws, it may provoke vigilante actions by some of those unwilling to wait for federal law enforcement action. That will undoubtedly be rather unpleasant.
The circuit in post #8 is quite similar to the ancient spark gap transmitter.
 

Thread Starter

Eagle111

Joined Jan 9, 2024
16
I appreciate your assistance of knowledge, but it is not the knowledge i seek. Your last three replies tell me that which i already know.

However, considering the extent of interference caused by such a device; perhaps it would be best for me to focus on lower amperage systems for the moment.

Although, I would still like this concept design completed. Any further suggestions on components and circuitry is appreciated.
 
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timm27

Joined Dec 11, 2020
13
I don't think your idea of using a HV capacitor to get a more powerful spark has been thought through properly. You would need to charge the capacitor until it reaches a target voltage and then switch it over to the 'spark gap' . You certainly could not do it with a mechanical switch - as Mister Bill2 says you would get a lot of arcing which is highly undesirable.

Many years ago I worked on a system to measure the impulse response of an airframe and we used a high voltage generator to charge a transmission line to multiple kV and we switched this into a large broadband antenna. This generated a sharp impulse step (defined by the length of the delay line), which then decayed and oscillated, but by then our measurement was completed. We used two gas discharge thyratron switches in a totem pole configuration. We only triggered one of the tubes, the other one fired by avalanche breakdown. The discharge current was estimated to be a few hundred amps, but just for the duration of the step.

This generated broadband interference detectable over a distance of several miles, but as our PRI was only one or two pulses every hour or so we did not get any complaints. The interference was in the form of a single click detectable across any band from a few 10's of kHz up to beyond the 100 MHz FM band - you get similar interference from lightening strikes in a thunderstorm.

Would this sort of approach help you at all?
 

Thread Starter

Eagle111

Joined Jan 9, 2024
16
I already have a unit on the way for putting out a single Pulse. And I don't plan on using an aerial, interesting information though Tim thanks for the response. And the Capacitor I intend to function more like a flutter valve while keeping the pulses more uniform in power. Also to clarify about the switch, it will be conducting through the air itself, not a contact switch.

After I have tested my smaller projects I intend to move onto this design; but I may not even need to depending on the results. If I do, I will be sure to be brief however, as to not cause much interference.

I am still interested in assistance to solve this circuit.

I would like to use a neon sign transformer, however to my understanding they are designed for a load, which is unsuitable for spark gap systems directly, so perhaps if i add a 1:1 ratio transformer to the neon sign transformer output, and then connect those outputs to the spark gap? would that be suitable? or perhaps just a neon transformer with an Iron core? Thanks in advance.
 
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MisterBill2

Joined Jan 23, 2018
19,051
You might consider investigating the newest "neon sign" supplies that do not use an iron core transformer, but a semiconductor oscillator of some type to produce the high voltage. I inspected one a while back, and according to the specifications, the efficiency was about 135%. (not a typo on my part) I suspect some rather optomistic claims were at work. The devices are less expensive and not encased in tar or silicone, so they can be investigated easily.
 

Thread Starter

Eagle111

Joined Jan 9, 2024
16
I am unfamiliar with semiconductor oscillators, I will research them. However for a modern neon transformer to work i will need three additional components that I have yet to find commercially available at such voltage levels. A surge protector, voltage regulator and frequency converter.

The simplest and cheapest solution, while also being reliable will be most ideal.
 
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MisterBill2

Joined Jan 23, 2018
19,051
The current, or fairly current, high voltage supplies for glow-tubes are not at all like the earlier iron-core mains frequency transformers. They use a high frequency oscillator and a very much lighter transformer that operates at a much higher frequency. So if you want to just produce one spark at a time, it would be simple to rectify the output of one of those to charge a suitable capacitor thru a resistor, and when the cap charged to a high enough voltage it could arc across a gap and deliver the high powered spark. That would be a high voltage relaxation oscillator, similar in operation to those that use an NE2 bulb and operate at about 80 volts or so.
It seems that the new power oscillator transformer replacement could be more easily controlled for voltage than the older technology.
 
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