🚀 go-pugleaf

Things to keep in mind when dealing with 555s in any kind of precision
application (besides deciding to use another part, heh heh heh) is that
you are working with a chip that has lots of high-gain op amps in it
right alongside a really beefy digital output structure.  Bypass the
hell out of it.  Don't leave pin 5 unconnected; bypass it.  And it
doesn't hurt to put a bit of isolation on inputs from the real
world; I'd use opto-couplers, LS14s, or sink resistors and diodes 
(in order of decreasing effectiveness).  The lower the impedance of the
input the less likely it'll false trigger.

If you can transmit with a 5-watt CB next to the unshielded 555 circuit
you've designed without ill effect, you can feel proud.
	- Brian