Hello Mark.
26 Apr 97 19:42, Mark Magill wrote to Roy Witt:
 MM>> neither will his other handheld radio in later tests.
 MM>
 RW>> Does that old simpatch use 556's as a tone decoder?  If so,
 RW>> you can tune them seperately by pressing two buttons...
 MM>
 MM>         You're right, it *did* use the 556's. He's come up with a plan
 MM> now to use a DTMF decoder chip instead that is "fail safe" (dangerous
 MM> word) at decoding the tones and has got it successfully decoding on
 MM> the test bench. Now it remains to disable the decoder in the device,
 MM> and insert the new.
The only way to go with today's technology.  I've got one of those patches in 
my junk box that was very reliable =after= I figured out how to tune the 
556's. Now-a-daze, I use a cell phone...
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