🚀 go-pugleaf

In article <17263@watdragon.waterloo.edu>, sekoppenhoef@rose.waterloo.edu (Shawn E. Koppenhoefer) writes:
> We have a phone at home that is shared between a computer and a person's
> voice. Furthermore... we have several telephones on that particular phone
> line. Is there some way of attaching an led or something to indicate
> by being on that the phone is IN-USE ? Something to prevent family members

Hello!  A few years back, my roomates and I had something like this on
our extension phones in a dorm suite.  We built the circuit based on
what someone else in the dorm was using--I can't say I knew how it
worked (I know very little about phones!).  As I recall, the circuit was
simply--

                                    |------->|-----|
     red lead  ------resistor-------|              |------ green lead
                                    |-------|<-----|

 where the  -->|-- are LED's.  Note that they are connected in opposite
directions.  If I remember right, the LED's flashed alternately when
the phone rang (nifty with two different color LED's! :)  and one would
stay on when the extension was off-hook.  It seems rather obvious how
this would work--if phones work in an obvious manner!

Anyway, this is certainly a cheap approach.  The resistor value you will
have to find experimentally--start large!  I think the phone ringing
voltage is ~100 volts, so maybe 5k ?

And finally, it may be illegal to connect this circuit.  It never caused
any trouble with our phone system, but I can't guarantee it won't affect
yours.  Maybe you could try it for a while and see what happens.

Best of luck!

Paul