For tail timer for repeater using 555 build as regular timer circuit with timing for like 3 sec or what you need and with transistor driven by COS ground pin 6 of 555 (transistor collector to pin 6, emitter grounded and COS driving base).? As long as having COS and pin 6 of 555 grounded output will remain high and when COS goes away letting pin 6 charge thru timing cap the output will stay high for timing and then drop.?
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Old circuit I used about 40 years ago.
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Can also make for CTCSS tone encode, let tone turn ON with COS, then tets tone turn off before TX drops. Make tone control timing less than tail timer.
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Yes better and easy to do with software, once get the circuit then easy to add software with a little hardware, hi.? Also more fun.
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73, ron, n9ee
