I always use an NPN transistor (2N4401 or whatever floats your boat) as an inverter on the Micor COR, with a voltage divider on the base. Micor COR to base through 10K, 4.7K from base to emitter, ground emitter, collector becomes active-high COR. Pull up collector with 12V through 1K (or whatever) if your controller doesn't have a pull-up internally.
--- Jeff WN3A > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Josh > Sent: Monday, June 21, 2010 11:58 AM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Micor COS issues.... continuing > > > > I've been fighting this issue for a while now. I've tried > some bandaids to deal with it, tried multiple repeater > controllers (including one I designed myself with an > ATMEGA328 Microcontroller (I'll probably be releasing this > design as open source coming up)... and I'm fighting the same > problem everywhere... My micor COS signal is weird. > > When the squelch is closed, I get right around 8 volts, taken > from pin 8 of the modified mobile audio/squelch board - the > tried and true process just about everybody uses..... When > the squelch opens, I'm at not ground potential, but right > about half a volt. This isnt really the sort of logic signal > I want (I want this thing to be dead nuts zero, not half a volt). > > What is the deal here? > > I've tried adding resistors in series to fudge things and > cause voltage drop, but thats not really even working that > well. I've tried the 2n2222 circuit, but that doesnt really > have a lot to do with this (although a variation of that > might come into play I suspect) > > How do I best solve this so I can get my repeater on the > air?? This is very close to the last issue I have remaining to solve. > > Help / advice is greatly appreciated. > > Josh > > > > >