Re: Help for an appliance operator
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Bill
FET input op-amps are a good idea because the gain can be set precisely
in the feedback loop part of things.?? Could turn out to be better than the
original tube design.
Good thinking.
Arv _._
Hi,
I have a "solid state VTVM" factory built as you suggest. It has FETs
and diodes. Another project I have in mind for a VTVM with an open power
transformer is replacement of the vacuum tube triodes with FET input
op-amps.
I also have a couple of V-O-Ms here that get used once in a while. No
Vacuum tubes. No transistors. No microprocessors. No ICs. No diodes.
Just raw Ohm's law and basic, passive parts at their most basic.
73,
Bill KU8H
bark less - wag more
On 8/17/21 7:14 PM, Arv Evans wrote:
> It takes a bit of re-engineering but it is possible to replace
> the tubes in a VTVM with solid state diodes and MOSFETs.
> lowering the supply voltage seems to be the most difficult
> part of the project.
>
> A slightly different approach might be to use a microprocessor
> and a dual ADC.
>
> Arv
> _._
>
>
> On Tue, Aug 17, 2021 at 5:10 PM Bill Cromwell <wrcromwell@...
> <mailto:wrcromwell@...>> wrote:
>
>? ? ?Hi Bob,
>
>? ? ?I have some that still do. A statement that suggests a VTVM is a DVM
>? ? ?with vacuum tubes is so far off. I have VTVMs AND DVMs. Each has
>? ? ?it's place.
>
>? ? ?73,
>
>? ? ?Bill KU8H
>
>? ? ?bark less - wag more
>
>? ? ?On 8/17/21 12:44 PM, Bob Kremer wrote:
>? ? ?> One more note I didn¡¯t see mentioned.? VTVM stands for Vacuum
>? ? ?Tube Volt Meter.? ?They worked very well!
>? ? ?> Bob-K5KL
>? ? ?>
>? ? ?>
>? ? ?>
>? ? ?>
>? ? ?>
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