Pull the trigger low through a capacitor...it will magically become a low-going pulse. 73, Paul, AE4KR
_____ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of w6jll Sent: Monday, April 21, 2008 5:03 PM To: [email protected] Subject: [Repeater-Builder] Carrier Control Timer 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
