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

[Tim Ressel]

A single OTA makes a 2-quadrant multiplier. There is a
circuit in the old RCA linear databook that uses 2
OTAs to make a 4-quadrant multiplier.

I wonder what a 2-quadrant multiplier would sound
like? 

By the way: If you're using square waves, an
exclusive-OR gate functions as a multiplier.

--Tim

--- Nils Pipenbrinck <np at inverse-entertainment.de>
wrote:
> 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
> 


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