Paul Anderson <wackyvorlon <at> gmail.com> writes:

> I'm familiar with building a VCO using varactor diodes, but I was
> wondering about other designs.  I was discussing this with my father,
> and suggested the idea of changing the biasing of transistors making
> it take longer for the voltage to come up.  Would this effect be
> pronounced enough to work?

Yes, look at 2-transistor astables with variable supply voltage f.ex. 

But in the radio sense the answer is it will work a little. F.ex. a FM 'bug'
transmitter can be FM modulated with just a few mV of audio to the base of the
oscillator. This causes the internal capacitances to vary varactor-like.

Peter



-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist