[sdiy] OTA based ringmods (was MC1496 discontinued..)

[Nils Pipenbrinck]

Scott wrote:

> And I *still* have not built an audio ring modulator.
> I have a need for a very basic ring modulator, I have as choices: 1496
> and AD633.  I also have LM13600 and LM13700.  Of these, what is the
> best choice for this?


Which reminds me of a question I wanted to ask for a long time:

How does an OTA based ring-modulator work?

I've examined some of the schemantics of iron-less ringmodulators. Of all
the OTA based designs I saw I still don't get how they should work as a
ringmodulator.

They directly used the Iabc as carrier or modulator input, and the +/-
terminals for the other signal. How can such a circuit can do a 4-quadrant
multiplication which afaik is what a ringmodulator is all about.

Will a 2 quadrant multiplier do the same job?

Thanks,
  Nils