Retriggerable VC One-Shot?

[Tim Daugard]

A voltage controlled current source feeding the timing cap on a 555 should
do this. I have used a constant current source circuit to generate a true
sawtooth with a 555. A pot controlled the sawtooth sweep rate and the 555
discharge transistor was used to discharge the cap. The data sheet for the
TI version of the LM 3900 has a schematic for a VC current source. (and a
VC current sink) They are on my list of things to play with in the future.

Tim Daugard

(with lots of bits and pieces and nothing completed yet
 - I'm a bass player what do you expect)

> How would you guys approach this?  Would you use a 555 timer in one-shot 
> (monostable) mode?  If so, how would you put its duration under voltage