Re: Q - Driving HV DC pulses? (fwd)

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Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Tue, 04 Oct 2005 07:36:57 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Q - Driving HV DC pulses? (fwd)


>----- Forwarded message ----------
>Date: Mon, 03 Oct 2005 21:52:29 -0400
>From: Jeff Bullock <jeff@xxxxxxxxxxxxx>
>
>
>Hi,
>
>I'm a newcomer to this list.
>
>I have been researching various HV applications. My particular interest is
>in building a pulsed DC high voltage generator. It could be useful for many
>types of experiments.
>
>My specific needs require that the power is generated from a 12 volt battery
>source and that the voltage pulses are of a moderate HV between 1kv and
>10kv.
>
>For experimentation it's important to be able to accurately control the
>duration of the pulse and interval between. The pulse wave needs to be a
>clean, square, DC wave with no polarity oscillations.
>
>That's why it would be ideal to come up with an adjustable 555 timer circuit
>that acts as a driver to trigger the release of a pulse from an MMC
>capacitor bank that has been charged by the initial HV generator. I'm
>concerned, however, that normal triggers in low voltage timer circuits like
>transistors and MOSFETs, are too delicate to take high voltage.
>
>Does anyone have information on how to time and trigger clean high voltage
>square waves?

What are your requirements in terms of:
1) Output current
2) Pulse width
3) Rise and fall time
4) repetition rate of the pulses
5) Jitter

How adjustable does it need to be?

FETs can do the job (you have to stack multiples in series).  So will a 
variety of tubes.

If you look around for "radar modulators" you'll find some information.

An invaluable source is the Los Alamos National Lab report by William North 
called "High Power Microwave Transmitters", which is available on the web 
at a variety of places.
(http://hot-streamer.com/TeslaCoils/OtherPapers/NorthReport/)  Lots and 
lots of useful design information.


>Someone suggested using a triode. I only know these as tubes from amplifier
>circuits. I've never heard of them being used as switches nor anything about
>their tolerance for high voltages.
>
>Thanks!
>
>Jeff