waveshaping

[Ingo Debus]

Paul Perry wrote:
> 
> At 08:35 AM 28/05/99 +0200, Ingo debus at cityweb wrote:
> 
> >There was a "Square-to-Saw-Converter" in Elektor a long time ago. I
> >built it back then, it worked pretty well.
> 
> Ingo, can you remember approximately how this worked?

There were two versions, a simpler one that generated expo saw, and the
other generating linear saw. The simpler circuit was only two trannies
and some passive components. A cap was charged via a resistor and
discharged via one of the trannies during the rising edge of the input.
The charging resistor was connected to a frequency dependent voltage
source. This was just another cap, charged during the falling edge of
the input via the other transistor. The higher the frequency, the more
often this cap was charged, and so the higher the voltage.
The linear saw version had a current mirror instead of the charging
resistor, and a FET output buffer.

Both versions could also be used as simple AR envelope generators, just
using the power supply as gate.

Hope I understood that article (Elektor 5/78) correct.

Ingo