[sdiy] multiplier from three 741s?

[Magnus Danielson]

Paul,

A reduction of Fig. 4 would be to let V12=V11 and V22=V21, thus letting 
the currents sum up directly, and then you can drop R12, R22, Rs12 and 
Rs22. Then, as Ted metions, you can use a 1458 or so.

If one is picky, A1 + input should have a resistor to ground, preferably 
in the neighborhood of R41//R51//R61.

Cheers,
Magnus

On 11/15/2014 11:34 AM, Paul Perry wrote:
> Back in the days before synths even, there were analog computers.. and
> many strange ways were used to multiply voltages.
> One way was to take the sum and difference of the two voltages, square
> the voltages (this being easier) and then take the difference.
>
> I think this link shows how to overdrive the 741 output stages to get
> the square function and so on.
> http://2005.iccas.org/submission/paper/upload/2multiplier.pdf
>
> I don't expect anyone to use this - but, if you do, I'd like to hear
> about it ;-D
>
> paul perry
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