Win's next 10kV project, a 1us ramp

Does the slope have to be continuously variable? What's the rep-rate? What's the load? What's the polarity? Got any hydrogen thyratrons in stock?

And, of course, what's it for?

John

Piece-a-cake ;-)

...Jim Thompson

MIT RadLab, volume 5, "Pulse Generators."

John

What's the load look like?

Best regards, Spehro Pefhany

How much current? I know this more or less the same question, but that's the answer the peanut gallery needs ... Jim Thompson's piece-of-cake would start to look a bit rash with loads above 1nF, which would need currents above 10A.

Hello Win,

Is it going to be a stack of FETs? Or can you use a tube?

Regards, Joerg

I hope you've had all the kids you ever intend to.

Be careful!

Bob

Hmm, I don't think the slope would be particularly accurate, though. Might could try an old technique of pulse regulating, or whatever it was called... it was used in tube color TVs. You use a chunky tetrode to switch the flyback, then a low perveance triode to load down the flyback pulse. This was used to indirectly regulate the high voltage supply for the CRT. Of course you need live feedback to control the rising slope or else do it with open loop correction, which would just make things trickier.

Huh. Hey Win, what's wrong with a big assed cathode follower? ;-)

Tim

-- Deep Fryer: a very philosophical monk. Website:

Whats the rep rate? Can you have some jitter at the low or high end? How much current?

I spend two days a week working in a lab that uses electrostatics. Its probably not fast enough or controllable for yout task, but when my boss asked for a fast 30Kv ramp, I ripped a vacuum relay out of a defibrillator , and got in a heck of a lot of trouble with the legal, purchasing, and safety offices for buying a unauthorized, uncertified, and used defib. But thats the easy way to get a decent vacuum relay these days without ordering a whole production run. To get it shipped I had the surplus company keep the paddles, that made the autocrats happy.

We have another commercial box made by the company that makes our HV supplies (Gamma High Voltage Inc.) that uses a color shunt TV triode acting as a switch up to 30KV, and to get a ramp we hang a RC off it. However no supply in our lab goes higher then 2 mA, so it may not meet your needs.

Steve Roberts

Not too bad, it's a 10pF electrode inside a vacuum chamber. Add another 30 to 50pF for a connector and some cable. Add the self-capacitance of a switch/amplifier/inductor/etc., and come up with a 0.5 to 1A charging current to move 10kV in 1us.

Or a 1-tube Miller rundown thing.

John

Are there any practical 12 to 15kV triodes, or pentodes?

"Winfield Hill" schreef in bericht news: snipped-for-privacy@drn.newsguy.com...

In Dutch, "ramp" means disaster. I'm still on the internet, so it hasn't happened yet. Sheesh, 9:23 AM and trying to be funny already ;)

Question given as a possible solution: Would it be acceptable to use a flyback transformer to add that waveform to a DC supply?

Microsoft security patch for the .wmf thing automatically came in early this morning.

Win,

EHT shunt regulators as used in old colour televisions may still be available and meet your needs. e.g. 6BD4 They would only have low heater cathode insulation so would need a floating supply for that.

kevin

Hard-tube radar modulators did tens of amps at voltages like 20K, with pulse widths in the 1 us range. Check RadLab volume 5 for circuits.

I was thinking about a classic glass jug like an 833A or something. Anybody know how much plate current one of these can manage? My transmitting tube books are at home.

There is a smallish tetrode (I think) that was used in HV power supplies, Kepco and such... got one around here somewhere. And of course the 6BK4, 25 kilovolt shunt regulator used in old color TV sets, but it wouldn't sink enough current for you.

John

You can't fool us. This is just a homework assignment.

John

John