component substitution

[Steve Wegner]

Hi, I'm new to this list and to synth building as well. I'm working on
an analog design based on some of the basic module schematics from Hal
Chamberlin's "musical applications of microprocessors" (they originally
appeared in Electronotes Newsletter). I've managed to round up most of
the parts(or equivalents), but am having trouble with a few:
Transistors----AD821 & AD818 matched pairs (pnp & npn, respectively)
                        2N3819
OP Amp -----CA3140 (BIMOS)
and last but not least, the elusive Q81 temperature compensating
resistor (-0.33%/degree C)

If anyone could tell me anything about these parts or their equivalents,
it would be greatly appreaciated.

Thanks,
SdUB