On Jan 27, 9:13*pm, axolotl wrote:
On 1/27/2010 5:00 PM, DoN. Nichols wrote:

* *Interesting. *I remember building an array of oscillators using
CMOS gates as driving elements,...

Back when I used to do this sort of thing, the standard method was to
use a varistor with a TC inverse to that of the capacitor. If you wanted
an LC oscillator, there was a ferrite core material that had a
complementary TC to polystyrene caps.

Kevin Gallimore

You were making low frequency sine oscillators?

The ones I worked with were all digital, even for 60Hz to synchronize
A/D sampling to the power line. The standard method was a VCO
referenced to a crystal or ceramic resonator, or the power line zero
crossing. I designed one circuit that counted down a coffee-cup-sized
rubidium beam reference, AKA an atomic clock.

A clever engineer taught me several analog tricks with spare CMOS
gates. One 4050 buffer with a resistor from out to in is a flip-flop.
Connect the input to the center of a SPDT switch, NC and NO to GND and
VDD, and it's a switch debouncer that holds the last momentary input
spike.

Schmitt trigger gates are very versatile:
http://www.fairchildsemi.com/an/AN/AN-140.pdf

jsw