Re: voltage controlled resistor

On 17 May 2007 14:19:55 GMT, et472@xxxxxxxxxxxxxxxxxxx (Michael Black)
put finger to keyboard and composed:

Franc Zabkar (fzabkar@xxxxxxxxxxxxxxxxx) writes:
On 16 May 2007 10:43:47 -0700, cary.niza@xxxxxxxxx put finger to
keyboard and composed:

Does anyone know of an IC chip or discrete component intended to be
used as a variable resistor whose resistance value may be controlled
by varying its voltage input/signal

About 20 years ago I encountered a device consisting of a light source
(LED ?) and a light dependent resistor. IIRC the part came in a
package that was not much bigger than a TO92 transistor. I think
similar schemes are used to provide noiseless volume controls for
musical instruments, eg the expression pedals for pianos and organs.

And the poster hasn't really given enough detail.

Those things, and you could make them yourself if you had the light
dependent resistors, tend to be the simplest solution, because the
existing circuit only sees a variable resistor. I gather though
that they tended to be not so linear vs control voltage, and I don't
recall them coming in a wide range of values.

I would hazard a guess that these devices were mostly used in volume
control applications where the user provided the feedback. Hence
linearity may not have been a big issue.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
.

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