on oscillators

[Tony Allgood]

>Before that I was in favour of triangle osc. but after the reported
problems,
and problems in finding a good pnp current source or avoiding ota/mirror
problems
I'm not so sure about it any more. Especially not if the saw is needed
for timing reference (sequencers, time discrete level network).

Hi Martin and all,

This last point is so true. I used a triangle core for my latest VC-LFO
design, but generating a good quality sawtooth that had no glitches or
f/2 modulation is difficult. I think I will go for sawtooth for audio
rate VCOs. Simple LFOs can be triangle cores; a single 13700 can
generate square, sine and triangle outputs. And the SSM2220 is still
available for the pnp pair. And for HFVCOs, the OTA based designs do
very well at speeds up to 300KHz.

Regards,

Tony Allgood  Penrith, Cumbria, UK

Modular synth circuits, TB303 clone and Filter Rack

http://www.techrepairs.freeserve.co.uk/projects.htm