[sdiy] multiplier from three 741s?

[Michael E Caloroso]

An interesting experiment would be to substitute Norton opamps.

MC

On 11/15/14, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
> 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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