Hi Wayne.

01-Mar-03 04:25:00, Wayne Chirnside wrote to Roy J. Tellason


  -=> ROY J. TELLASON wrote to WAYNE CHIRNSIDE <=-

 RJT>> Wayne Chirnside wrote in a message to Tom Walker:

 WC>> Roy mentioned the 3909 flasher chip which would allow you to
 WC>> flash a high efficientcy LED at low duty cycle making that less
 WC>> of a concern.

 RJT>> Yeah,  but that box had batteries in it...

 WC> Capacitor, limitiing resistor and a couple diodes or zener would
 WC> take care of that. I don't think the 3909 cares if it has one
 WC> battery and a cap or two charged caps to stack. All it is is a
 WC> comparitor and switch anyway.

if you try and run the LED off the phone line you'll introduce switching
noise each time it fires.  also you need to proof the circuit against the
100V peaks of the ring signal, and have it go low-drain while the phone is
on hook and the line is at about 48V.


 -=> Bye <=-

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