ULTIMATE HVHF Amplifier / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

ULTIMATE HVHF Amplifier

previous 1 2 3 next

Move Thread

LAN_403

HV Enthusiast

Sat Jul 25 2009, 01:21PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

rororo74 wrote ...

The ultimate goal I envision of this effort should be only one - High Voltage (>=1KV), High Frequency (>=1MHz) pulses.
I mentioned capacitors in my first post, because they can be discharged rapidly instead of using MOSFETS. My gut feeling tells me that capacitors should be used and this is why I am giving up on the idea of exact amplification of the pulse (generator signal will only be used as a timer - duty cycle controlled separately maybe).
Feasibility study anyone (have you seen something like it on the market)?
Go easy on me guys and thanks again! :)

Not sure what you mean by "instead of using MOSFETs." You still need some sort of switching device. Capacitors alone aren't going to give you 1MHz pulses.

To be honest, I still don't know what you are trying to do here. Whats the application? What are the exact requirements? Stating >=1kV and >=1MHz doesn't really mean anything unless you bound it.

rororo74

Sat Jul 25 2009, 04:35PM

Registered Member #1124 Joined: Fri Nov 16 2007, 01:42PM
Location:
Posts: 17

What I mean is that instead of going the "Class-X amp" way, I prefer to use capacitors for the discharge. I want to move away from the traditional paradigm of using e.g. MOSFETS to pull the voltage up to the HV line (e.g of a neon transformer) based on the generator pulse. Instead I would rather charge capacitors and discharge them to output (solid state switches may still be used but I guess will have a similar or completely different purpose).
From the responses I have received so far, I assume that such a device has not been encountered yet. I certainly have not seen something like this yet.
You are asking me for an application. Please respect the fact that I cannot reveal what I have in mind for it at the moment, but I am willing to sponsor and develop this with all details in the public domain. If what I have in mind works in practice, everybody will be able to copy and even improve. If that isn't fair, then I am open to suggestions.
First of all I would like to know if this is viable. Is anybody interested in working on such a device?

Steve Conner

Sat Jul 25 2009, 06:35PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I'm personally not interested, I already have all the paid consulting work I can handle.

If you're going down the "triggered pulse" route, you might be interested in avalanche transistors. I've made triggered pulse generators with these that have rise times under 1ns and produce energy up to 1GHz, but the pulse is only about 12V peak. But Zetex make special avalanche transistors that can handle about 200V (the ZTX413/415) and you can stack them in series to get kV pulses.

Finally, nobody here has much patience for these OMG top secret applications. It's some sort of free energy device or ion craft, right?

rororo74

Sat Jul 25 2009, 07:31PM

Registered Member #1124 Joined: Fri Nov 16 2007, 01:42PM
Location:
Posts: 17

Steve, thanks for taking the time to post some quite useful comments. I will look into it.
For the time being I reserve my right to privacy regarding how I will apply this device. I am however at liberty to let you know that it is not either one of the two you just mentioned.

Any more ideas people?

jonny5

Sat Jul 25 2009, 08:22PM

Registered Member #1807 Joined: Tue Nov 11 2008, 07:36AM
Location: San Luis Obispo, California
Posts: 19

Are we to assume that the overall energy throughput is low? If you are talking about capacitive discharge, the energy stored in the cap is proportional to voltage^2. So, even a small-ish capacitance w/ kilovolts can equal a respectable amount of energy. Marx generators, for instance, charge HV caps in parallel and discharge them in series to obtain very fast rise times at very high voltages...all well and good, if you are looking for low frequency operation. By discharging even a small amount of energy millions of times a second (MHz), you are talking about a fair amount of power. I've heard of triggered Marx generators that may (or may not) negate the use of HV semiconductor devices, but nothing at your frequency range of interest.

I certainly respect your desire to make such a project as open-source as possible, but, by your description, such a power supply could output lethal currents. Many individuals on this forum possess the aptitude to design world-class high voltage power supplies (no meager feat!). However, these individuals have years of experience working around high voltage, and I think it is safe to assume that they have a healthy respect for the dangers posed by high voltage/ high power (all the more dangerous when one starts working with HV capacitive discharge). In the end, perhaps it is best to let people develop their own knowledge (of course, lending the proverbial helping hand when one sees fit). The intention is not to maliciously withhold information; technology allows us to share vasts amounts of data and ideas, but no technology exists as of yet to impart wisdom and common sense! This only comes by experience, hard work, and learning from our mistakes. I'm glad my professors in school didn't just give us all the answers to the tests and projects on the first day of classes. Sure, I might have learned a lot in the end (I still have no idea what stoichastic processes is all about), but they would have robbed me of the chance to learn how to learn!!! I apologize if that weak analogy didn't make any sense.

Good luck with the project, and (as always) be careful.

Hazmatt_(The Underdog)

Sun Jul 26 2009, 08:00PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

MHz barrier... hahahah.. I'm trying to get the high power audio designs to pass 100KHz and they won't do it!!

Not to mention if your amp design loads properly into 8 ohms and 50V... the reflected load and matching transformer to get that to 1KV would be insane! The wire won't fit on the core.

Steve Conner

Sun Jul 26 2009, 08:23PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Matt, can you post a link here to the various threads you have on your amp experiments? I think the original poster would be interested.

Hazmatt_(The Underdog)

Sun Jul 26 2009, 08:59PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

I can, I can give that a shot.. Unfortunately there isn't much good information just yet.. its still premature.

What he's looking for is a broadband transformer coupled amplifier like the 1040L from ENI, but that's over $12,000, heh.

Hopefully I will soon add the transformer coupled pre-amplifier to one of the threads which will drive the power stage.

Mos Amp that I will come back to a bit later:

Low Power "pinger" for coils, could be used as a pulse driver for trigger coils:

Here's a link to some amplifier research I'm doing for Turkey9:

So far I have reached 100KHz @ 100W into 8 ohms, 8 ohms because this is what the amplifier loads properly into without ringing. It should amplify triangle waves as well as sine waves, but square is going to be a tough challenge because that's going to determine the response of the amplifier, and I don't think its fast enough for that realistically. If you wanf fast pulse you'd be better off designing a fast pulse amplifier for that purpose.

I hope to have more sometime soon. I need a broadband transformer coupled pre-amplifier capable of a few watts first, and I'm working on that.

rororo74

Tue Jul 28 2009, 01:36AM

Registered Member #1124 Joined: Fri Nov 16 2007, 01:42PM
Location:
Posts: 17

jonny5 you are right in your estimations. It will probably be a lethal machine, but then again, so is a microwave oven! Right?
I may not be a seasoned HV experimenter, but this is why I came to you for advice. I understand the dangers involved and would not attempt such a feat by myself. To be honest with you, if such a thing exists on the market, I would rather purchase it (if it is within my means) and when I finalize the operating parameters build a specialized device. You mentioned apex and amplifier research. Not exactly what I am looking for, as these are amplifiers and I think I will be pushing the 2KW mark anyway (from the pricing, I understand now, the kind of work that must have gone into them!).
On the other hand, even if I manage to build a simplified pulsed capacitor solution, I do not know how long they would last at 1 MHz.

rororo74

Tue Jul 28 2009, 01:50AM

Registered Member #1124 Joined: Fri Nov 16 2007, 01:42PM
Location:
Posts: 17

Hazmatt: The 1040L from ENI seems to be along the lines of what I was thinking of initially. Actually I may just look for a similar product that can do 1MHz at a higner wattage, and rent it to give it a try.
Do you know of something similar that uses capacitor charging/discharging at HF?

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob