[sdiy] Fairchild H11F1

Scott Gravenhorst music.maker at gte.net
Fri Aug 9 16:34:24 CEST 2002

Interesting info.  I'm going to collect some data on that and see how bad it
is.  I plan to build a V-I converter to drive the LED (actually two in
series) and collect current vs resistance data to find:
1) the most useful current range.
2) see how well two randomly selected devices track.

This data does not appear in the data sheet.

I will post data and graphs on a web page.

"jhaible" <jhaible at debitel.net> wrote:
>> This looks like a really neat device for phasors and VC envelope
>> or anything where you want to piggy-back to an existing circuit to make it
>> controllable. I have a cabinet-mounted programmable Minimoog that has
>> Vac-Tecs soldered across the envelope pots and filter emphasis, and this
>> looks like it would provide a great way to do the same thing.
>I think it's just a FET with optical input instead of a gate electrode.
>So the voltage range for linear, resistive operation ("VCR") is very small -
>just as with any FET. You can operate it at higher voltages, but then it's
>(approximately) a VC resistor anymore, it's (approximately) a VC current
>source then. So in a VC ADSR it would turn the exponential slopes
>into something more or less linear. Not much different from an ordinary
>opto coupler with BJT I would presume.
>Vactrols are very different - real resistors even for high voltages.

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