> I want to know if I could build a simple sample and hold circuit with
> just a couple op amps on a small bread board with a +5 volt DC power
> supply that would do this:
>
> I am watching 2 voltages. When one voltage crosses +.412 Volts DC, I
> want to be able to hold the other voltage for about 3 seconds so that I
> can read it with a DVM. The held voltage would be anywhere from about
> +.255 volts to +.500 volts dc, and I need the .001 volt resolution.

Hi John,

Yes, it wouldn't be that hard. You'd need a JFET or an analog switch as well as
the two opamps(actually one opamp would be used as a comparator, if the slew
rate of your signals is very high you would need to use a comparator rather than
an opamp).

Doing it with a PIC would require the two opamps to get the signals in range,
but no FET or analog switch. But your speed would be limited by the PIC.

Cheers,

Bob

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