At 08:00 PM 11/30/04, you wrote:
>I have a Motorola radio that has an active low COS signal. I need
>this to be an active high COS signal. Does anybody know how to build
>a simple circuit that will invert the COS signal from a low to a
>high signal?
>
>Thanks
>
>J
What controller do you have that can't take either polarity of
a COS signal?
Look in my Mitrek Interfacing writeup at
www.repeater-builder.com - go to the Motorola page, then
the Mitrek page, then the Interfacing document. In the COS
section I show how to get either - just read that section and
look at the schematics and all will be made clear, grasshopper...
(if you don't grok the reference, go rent Karate Kid 1)
Basically you ground the emitter of any old NPN transistor,
and put a 10k in series with the base and another in series
with the collector. Run the collector resistor to + voltage...
+5, +9, +12, etc...(whatever your controller uses as a "high").
Run the base resistor to the signal source. The raw
collector will be your signal output.
Mike WA6ILQ
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