Competition: High Voltage Power Supply

[DerStrom8]

To get variable current and voltage he is going to have to use a inverter drive of some sort and to get to 20 KV at 1200 watts continuous duty this thing is most likely going to need a custom wound transformer regardless of what frequency it's running at and none of this is going to be overly small or cheap.

As far as variable voltage and current goes with NST's that's easy. Just use two variacs. One is the voltage control and the other is wired in series with the NTC transformers primaries to work as a variable inductance type current limiter.

Standard old school Tesla coil driver circuit tech.

The problem with using NSTs and Variacs is that they're very large and heavy. Again, the host would like the setup to be as small and lightweight as possible. Otherwise, I'm sure he would have already used the setup you describe.

 

[Mr RB]

I already see some potential issues.

60 Ma at 20 KV is 1200 watts which is way past what a typical flyback transformer from a CRT type TV or monitor will handle.
...

That TV flyback transformer is rated about 100W, you can't get much more than that or the ferrite core will saturate.

Also as Nigel said the flybacks already run "hot" in a 120W TV set where the flyback might be running at 60-70W, making a mA or so. I think anything more than 100W will only be sustainable for "short term abuse" type running.

I'm not trying to shoot down the competition but so far in this thread you've got 3 experienced TV guys all raising an eyebrow...

It might be possible to make 20kV reliably, and it might make 60mA when actually arcing (at a much reduced voltage (maybe 2kV?) but to make a lot of mA while at 20kV is not going to be possible with that flyback unit.

 

[DerStrom8]

That TV flyback transformer is rated about 100W, you can't get much more than that or the ferrite core will saturate.

Also as Nigel said the flybacks already run "hot" in a 120W TV set where the flyback might be running at 60-70W, making a mA or so. I think anything more than 100W will only be sustainable for "short term abuse" type running.

I'm not trying to shoot down the competition but so far in this thread you've got 3 experienced TV guys all raising an eyebrow...

It might be possible to make 20kV reliably, and it might make 60mA when actually arcing (at a much reduced voltage (maybe 2kV?) but to make a lot of mA while at 20kV is not going to be possible with that flyback unit.

Thanks for the input RB. This is why the host has said he will consider any other transformers, though preferably they should be small and somewhat lightweight.

 

[DerStrom8]

The host has suggested a circuit for a plasma speaker, though the audio modulation is unnecessary. It's much lower current (nowhere near 60mA) but he says it will work. He's also wondering how long it might be able to run for.

https://www.youtube.com/watch?v=PJpn2PzhvP4

The first thing I see is the heat sink, which would have to be increased in size for long-term operation. But other than that, what is the plausibility of this? Just another thought to get you guys going

Regards,
Matt

 

[tcmtech]

So once again what exactly is he wanting to do with this 20 KV @ 60 ma and what form of output does he need, low frequency AC, high frequency AC, clean DC, or some form of PWM based output?

This is what is going to ultimately determine the overall design and so far all we know is it may need to handle around 1200 watts in a long term continuous duty working condition.

 

[DerStrom8]

So once again what exactly is he wanting to do with this 20 KV @ 60 ma and what form of output does he need, low frequency AC, high frequency AC, clean DC, or some form of PWM based output?

This is what is going to ultimately determine the overall design and so far all we know is it may need to handle around 1200 watts in a long term continuous duty working condition.

That is something the host has not told me--the final application. I assume he's looking for an output similar to the one you would find in the television set application, and able to run for long periods of time without damaging components. Output is usually high frequency DC. Again, the current spec is not firm. As long as it is enough to sustain an arc rather than just a series of sparks, it will be enough.

 

[DerStrom8]

I have edited the original post. Phrases labeled in bold have been changed.

 

[tcmtech]

Too vague for me.

 

[DerStrom8]

Too vague for me.

Which part, specifically?

This project is not about matching criteria, it's about exercising ingenuity and trying to make things work the best you can. Don't feel held down by the guidelines. Take an idea and run with it. There is nothing to match specifically, so there is not much of a need to specify anything any further. Use your mind. Everyone will be judged fairly and without bias.

 

[tcmtech]

The part that's to vague for me is what output and what purpose this device is supposed to be for.

If its just to make a simple high voltage arc regardless of being AC, DC, high frequency or low frequency based that's simple and easy to do but if it's for a plasma speaker or some application specific job that requires regulation and feedback control for a high powered PWM type drive system that's a whole different level of design criteria to deal with.

Right now your friends request is like me saying I need an engine designed to drive something and it should have up to 120 HP.

To make it a valid request for what type of engine I would need you would need to know what is the engine for, what RPM range, what fuel source, what cooling method, what the engine is being connected to, and other technical things like that. An engine designed for an aircraft aplication is completely different than one designed for a tractor despite them both having a 120 hp rating.

The point is without defining what this HV power supply is for and what its specific output is being used for its too vague of request.

That's my thoughts.

 

[KeepItSimpleStupid]

So it's probably bigger than a bug Zapper i terms of power? A Jacobs ladder can be any size.

 

[DerStrom8]

So it's probably bigger than a bug Zapper i terms of power? A Jacobs ladder can be any size.

Yes, it should be about 20kv and enough current to maintain a steady arc. That should be simple enough. There's not much more you need to know. Frequency isn't important, and I don't think it matters if it's AC or DC.

EDIT: I have spoken with the host and he says the output should be DC to match the output of the flyback. Since flyback outputs are generally only half-wave rectified, you should be able to use a single diode.

 

[tcmtech]

Yes, it should be about 20kv and enough current to maintain a steady arc.

That's a pretty vague description again. A sustained arc in open calm air can be done with a few micro amps at 20 KV.

What is he intending to do with this arc?
If its just to make a HV arc for arcs sake literally then all he needs is a simple flyback transformer from a old CRT type monitor with a simple single transistor oscillator circuit to drive it . The AC or DC output part is irrelevant.

How big of arc does he want? At 20 KV and <1 ma he will be able to draw out maybe 2 inches of arc length at best but at 60 ma he might draw it out to nearly a foot!

 

[tvtech]

It is a Secret .

Only enough Info to work with. No more needed.

Smacks of a design I did for someone once. Secret. Gave the bare essentials. And then rejoiced when he got his "One working unit" he needed in order for his Patent to be accepted.

He ran with the Patent...and still has made nothing out of it. Bitter, twisted fool. And I made his stupid idea a reality.

Never again. Not worth the time and effort......are you listening Matt???

In fact, hopefully you are ALL listening.

People who dream up things must not sucker other people into becoming a part of something they canno't develop themselves. Or at least PAY the development cost....

Not fair. Especially where the Developer does all the work for a Stupid dreamer. And makes no money out of it. Suckered once...never again.

Promises of huge payouts "once it takes off"....anybody heard that before?

Regards,
tvtech

 

[jpanhalt]

Clarification:

Does the inventor have to produce a device or just a design to get the award?

If device does it have to be delivered? If yes, at whose cost?

Is there a limit on the construction costs for the design?

How much voltage drop is allowed at 20 mA current? (Assuming 20 mA would meet the rather indefinite "requirements.")

John

 

[DerStrom8]

That's a pretty vague description again. A sustained arc in open calm air can be done with a few micro amps at 20 KV.

What is he intending to do with this arc?
If its just to make a HV arc for arcs sake literally then all he needs is a simple flyback transformer from a old CRT type monitor with a simple single transistor oscillator circuit to drive it . The AC or DC output part is irrelevant.

How big of arc does he want? At 20 KV and <1 ma he will be able to draw out maybe 2 inches of arc length at best but at 60 ma he might draw it out to nearly a foot!

I know you're just picking at it now, tcm. I have given you all the information I have. It doesn't NEED to be any more specific. This is not a specific project, from what I have been told. This is the last time I will respond to your picking. I understand that you want a specific description, but the point is that there ISN'T one. This project is very basic and doesn't need a specific description of what it's supposed to do.

A few micro-amps is nowhere near enough to cause an arc. Sparks, yes, but an arc, no. You seem to be getting the two mixed up.

As for your current vs. arc length estimations, they are WAY off. Depending on the surrounding air, you need around 5mA to sustain a steady arc. Much less than that and it will start to look more like small sparks (little thin blue lines). <1 ma, you'll hardly have an arc to "draw out". And 60 mA is NOWHERE near enough to draw it out a foot. 60mA at 20kv will only get you about 3 inches, max.

Now, are you thinking of participating in the competition or not? If no, then stop picking at it. There is more than enough information there for this project to be completed, and for a winner to be selected. You don't need any specific details.

It is a Secret .

Only enough Info to work with. No more needed.

Smacks of a design I did for someone once. Secret. Gave the bare essentials. And then rejoiced when he got his "One working unit" he needed in order for his Patent to be accepted.

He ran with the Patent...and still has made nothing out of it. Bitter, twisted fool. And I made his stupid idea a reality.

Never again. Not worth the time and effort......are you listening Matt???

Regards,
tvtech

I hear you tvtech. However, the host of this competition is a respected member here. It's not some random stranger or anything like that. I assure you that he can be trusted

Regards,
Matt

 

[DerStrom8]

Clarification:

Does the inventor have to produce a device or just a design to get the award?

If device does it have to be delivered? If yes, at whose cost?

Is there a limit on the construction costs for the design?

How much voltage drop is allowed at 20 mA current? (Assuming 20 mA would meet the rather indefinite "requirements.")

John

Good questions John.

This competition is primarily about the design itself. If you wish to build it as you design it, feel free, but the actual device you build will not be judged. The individual designs will be collected on this thread until March 1st. On March 2nd, the submitted designs will be judged by the community to pick the top 5. I will personally build these designs to test how well they operate, and pick the one that most closely matches the desired criteria.

As far as I know, there is not a limit on the construction costs, though it should be built with off-the-shelf components/parts, the cheaper the better.

And as for the voltage drop, I will have to consult the host. The 20kv is another value that is not firm, so I expect it would not matter much. I believe the host would simply like to match the operation of the flyback in the TV application as close as possible.

Hope this helps.
Regards,
Matt

 

[tvtech]

I know you're just picking at it now, tcm. I have given you all the information I have. It doesn't NEED to be any more specific. This is not a specific project, from what I have been told. This is the last time I will respond to your picking. I understand that you want a specific description, but the point is that there ISN'T one. This project is very basic and doesn't need a specific description of what it's supposed to do.

A few micro-amps is nowhere near enough to cause an arc. Sparks, yes, but an arc, no. You seem to be getting the two mixed up.

As for your current vs. arc length estimations, they are WAY off. Depending on the surrounding air, you need around 5mA to sustain a steady arc. Much less than that and it will start to look more like small sparks (little thin blue lines). <1 ma, you'll hardly have an arc to "draw out". And 60 mA is NOWHERE near enough to draw it out a foot. 60mA at 20kv will only get you about 3 inches, max.

Now, are you thinking of participating in the competition or not? If no, then stop picking at it. There is more than enough information there for this project to be completed, and for a winner to be selected. You don't need any specific details.



I hear you tvtech. However, the host of this competition is a respected member here. It's not some random stranger or anything like that. I assure you that he can be trusted

Regards,
Matt

Why then Matt does this respected person not post himself......instead of putting you in the middle of this madness

Regards,
tvtech

 

[DerStrom8]

Why then Matt does this respected person not post himself......instead of putting you in the middle of this madness

Regards,
tvtech

I couldn't say for sure, tvtech. I suppose a little anonymity couldn't hurt when you're hosting a competition. Helps keep you separate from the participants until the end.

Regards

 

[Mr RB]

The part that's to vague for me is what output and what purpose this device is supposed to be for.

If its just to make a simple high voltage arc regardless of being AC, DC, high frequency or low frequency based that's simple and easy to do but if it's for a plasma speaker or some application specific job that requires regulation and feedback control for a high powered PWM type drive system that's a whole different level of design criteria to deal with.
...

I agree some more information would be good! ie whether or not the voltage or current will eventually need to be modulated.

Also, many types of "arc" condition will expose the secondary winding to potentially high currents that could kill it (as the winding wire is incredibly fine) especially since this might be some DC app where output capacitance might be an issue. So some form of arc current control might be a good idea, even if just a primary max current limiting.