[sdiy] pin 5 3080

[Martin Czech]

:::The 3080 is not being used as an opamp in the MicroMoog -- it's being
:::used as an instrumentation amp.  Very different.

Yes, I forgot to mention a "little" detail: with Iabc and the current to
voltage converter (resistor) one can tailor the open loop gain very small,
this is something you can't do with a typicall op amp, they have as much
gain as possible, thus always need fedback and precision resistors. This
way you can build a cheap difference amplifier with good common mode
suppression and moderate gain, aka instrumentation amp.

The minimogg needs a couple of possibly matched npn (Rene Schmitz'
observation) for the same purpose,  soldering in a 3080 is much easier.

Of course, the 3080 will act nonlinear for large signals, but we allready
know that this is compensated by the ladder input differential stage in
the pass band.


m.c.