Minimoog oscillator

[Harry Bissell]

Hey Tony (et al...)

Well.... Its a week later and I found the minimoog mystery...

The slew rate of the buffer amp is slower than the fet/capacitor
discharge time... I bumped into it by accident during spice simulation.
I was trying to apply a MOSFET (VN1206N) for ramp discharge. I got the
discharge very fast (actually less than .05uS) but then the ramp
apppeared to keep rising after the fet was already off...

Then I found out that the cap was reset fully, but it took .5uS to get
to 6 volts (haha at 13V/ uS that's just about right...)

The LM318 is the best buffer I've found, with slew rate of 50V/uS its
about the best you can find... but I don't know if the input bias
current will be low enough in practice (its not a FET buffer...)

The TL07x is really not a bad choice...

Intusoft.com has a really good site with Spice Links... SGS/Thompson has
good models for most common IC's including the LM393 which I am now
using...

:^) Harry