The 555 will do the job just fine... you need only configure it properly, which for me ended up being the same circuit Hamtronics used in their early COR-2 Board. Simply copy that circuit less the hang timer portion and you're set.
I wish I could claim credit for it... but the circuit design was originally done by Hamtronics (Jerry). I and a few other group members can Email you the diagram if you contact us direct off the list. Most of us group readers via the web don't receive email attachments through the yahoo groups anyway. The really nice thing about billing things from kits is how you end up keeping good circuits around for use in other applications. The COR 2 Circuit is a great circuit, wish they still made and sold the kit, but now I "roll my own". cheers, skipp skipp025 at yahoo.com > "w6jll" <[EMAIL PROTECTED]> wrote: > > With regard to Tom's use of a carrier control timer - I am using GE > EXEC II and MVP's in my system. Although I have relied on the external > controller's time out functions, I would like to have a "backup" timer > in the transmitters that would take the repeater transmitter off the > air at say 10 minutes, if for some reason the contoller circuit failed. > I've looked at the 555 but the problem is that in the monostable mode, > the pulse input to start > the cycle has to be shorter than the timing cycle (according to some > design notes, about 1/3rd or less). Obviously, this won't work for the > intended application since the pulse (key down) would be longer than > the timing cycle. I'm sure someone on the bulletin board has > designed/implemented what I'm looking for. Any thoughts would be > appreciated. TNX Fred W6JLL >
