[sdiy] High Voltage Opamps ?

[René Schmitz]

There are also some high voltage driver circuits in the National Semi
Appnote 72.
There are circuits of inverting and noninverting high voltage drivers made
out 
of an LM3900 and a high voltage driver transistor. These circuits could of 
course be done with a tube too.

Cheers,
 René


At 15:19 29.01.02 +0100, Michael Buchstaller wrote:
>>Add a Tube output stage to your opamp !
>
>Good idea. But simply adding the tube´s grid to the opamp output will
invert the signal,
>not ?
>Assume i want a non-inverting amplifier with a gain of 50. What will i
have to do ?
>Just wire the Opamp as a unity-gain buffer, and then use feedback from a
490K/1K divider
>somehow ?
>
>>You will need some extra compensation of the opamp because of the extra
gain of
>>the tube stage.
>
>What kind of compensation ? A Cap from the output to GND ?
>
>>I've seen headphone amps like this. While I wouldn't really want an opamp
in a tube
>>HP amp, it should be ok for static and low frequency measurements.
>
>Hmmmm.... I remember some old Philbrick schematics, where they made an
opamp building
>block from 2 ECC´s - i built that once and made a simple (but working)
Twin-T resonator with it...
>Maybe i could just use *that* as my opamp....
>
>
>-Michael Buchstaller
>
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