[sdiy] OP AMPS for simple lfo circuit ?

[Tony Allgood]

>To sum up the results, the SHARP IR9022 was the best performer for
symmetrical swing about zero volts.

Good work Mike. A word of warning though, all op-amps will clip at
different levels depending on output load. This effect will probably
affect negative and positive levels differently.

I think the best way, is to use a discrete transistor output stage,
similar to the one used in the E&MM Spectrum's LFO. This pretty much
slams the square right up to the rails. You could also use an analogue
FET SPDT switch too.

Another way, is to trim/offset the threshold levels of the Schmitt
trigger to get a nice triangle. One trimmer will do this quite well,
although it won't improve the square horizontal symmetry. But my own
preference is to use a unipolar square wave. So I simply use a diode
from the output of the comparator to give me roughly 10V max and 0V min.

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan