[sdiy] Multiplier built from op-amp

[patchell]

    I assume you are refering to using the JFET as a voltage controlled
resistor...

    But, No, there is no way to make a multiplier out of a regular opamp...which
is a shame when you think about it.

    To make a multiplier you need something whose gain is dependent on some
variable (current, voltage).  Your best bets are Operational Transconductance
Amplifiers (OTA), such as the CA3080, CA3280, LM13600, LM13700, NE5517...and a
few others I am sure.

    You can also use discrete transistors or transistor arrays to do the job,
but, this gets a little more involved.

    For Info on using the CA3280 goto
:http://www.oldcrows.net/~patchell/archives/archives.html

    You will find lots of misc info that can be applied to any OTA.

Timo Weggen wrote:

> Hello,
>
> does anyone of you know a way to build a voltage multiplier (or call it vca)
> using op-amps without a JFET?
> TIA.
>
> Timo

--
 -Jim
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