[GreenKeys] Distortion problems

[Jim Haynes]

On Wed, 8 Jul 2015, Ralph Mowery wrote:
> hapens.  Just think of the time it would take and how difficult it would be 
> to get a square wave generator that you can vary the voltage from 12 volts to 
> 200 volts, then change the resistor and hook all that up to a scope to see

Well you could, with an ordinary signal generator, change the part values
and the time scale so that with 2 volts square wave you could see what
would happen with the actual circuit.  Of course you have to be very
careful to get the scaling right.  But in analog computer days that was
a way of life.

Back in 1929 Loy Barton devised a circuit to reduce the harmonic content
in the output of a broadcast transmitter.  He didn't have the instruments
to measure what the circuit did, so he built a version of the circuit
scaled to operate at low audio frequencies.  That allowed him to use the
oscillograph - a mirror galvanometer tracing a light beam on moving
photographic film - to see the resulting waveform and how it was improved
by his circuit.