[net.consumers] RS phone cords and illuminated dials

eric@chronon.UUCP (Eric Black) (03/12/86)

> I have several AT&T phones with illuminated dials that light up even
> though I only connected two wires.  Durned if I know how they do it ...
> 
> -=- Andrew Klossner   (decvax!tektronix!tekecs!andrew)       [UUCP]
>                       (tekecs!andrew.tektronix@csnet-relay)  [ARPA]

These phones use high-output LEDs in series with the phone line.  The
voltage drop across the LEDs is low enough (~3V for 2 of 'em) that the
phone is not adversely affected.

-- 
Eric Black   "Garbage In, Gospel Out"
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