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HV design problem

As a start... what limits G-S voltage?

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson
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All the 1N4148's are doing is limiting reverse G-S voltage, NOT forward.

If you are exceeding 20V G-S who knows what may be happening.

Put zeners in there NOW!

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Hi

I have done some experimenting with a HV power supply design. I have posted my regulation design here:

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The problem is this when I reach about 270V output it starts to oscillate and I have some very nice sinus curves at the output. Under and over 270 there is no problem.

I tried to follow the example in AoE page 372 and placed some caps (100nF) on the divider resistors but that blew the first to of my fets.

Any help?

Peter

Reply to
Peter Andersen

I know the right way to do it is with zeners. In this one I just use

1N4148 - but surely that couldn't have anything to do with this problem? in the final design I will off cause have some zeners!

Peter

Reply to
Peter Andersen

1) Why don't you drive the 100K divider and first FET gate from the "pulldown", dispensing the 470K chain? 2) Why don't you use one FET?
Reply to
Robert Baer

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