A slight idea for continuous harmonics generator?

Smilen Dimitrov smilen at itl.com.mk
Tue Sep 29 00:35:27 CEST 1998

Hello all,
hopefully some of you will give me some input on this. Well, lets say we
have the audio signal x. And then, lets bring it to a log amplifier,
assuming that its logarithmic function is defined in the 0 and for the
negative values. Also, let's use a natural logarithm; then at the output we
should have ln(x). Then, let's take that signal and take it to one of the
inputs of a four quardant multiplier. And let's bring the signal y to the
other input of the multiplier. Then the output from the multiplier should
be y*ln(x), and after bringing this signal to an exp amplifier we should
get something like 
So, this is my idea. Basically, if you can change the y signal continuously
(let's assume it's just voltage) then, if say y is 0.94 (I have no idea
what, volts maybe? - might take some tuning) then we should get something
that would be a hrmonically rich function I assume. Making y a 1 would give
us the exact same signal, then between 1 and 2 again signal rich in
harmonics, and then, for the value of 2, if the x=cos(wt), we should have
x²=½(1+cos(2wt)) - second harmonic. And so on and so on. 
I want to know if anyone ever bulit something like this, or if anyone has
any idea on how to make that log part at the beginning defined in the 0 and
for the negative values (maybe add somecircuitry - a comparator that will
route the signal, depending on its polarity, to two different log amps, and
then at the end put them back together)...
I might have not done the math correctly, too, so, in that case, sorry if I
wasted your time. But I'd really like to know if someone did this, and if
this is really impossible to do..

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