Wayne Chirnside wrote in a message to Charles Angelich:

> certain value. The teleprotector is a diode bridge and SCR 
> arrangement that senses the phone line voltage, on hook, off hook, 
> and if it detectect low voltage off hook conditions it effectively 
> opens the phone line downleg of the protector. I originally bought it 
> so if I picked up the phone during a download it wouldn't interfere 
> with the download. Think of it as an automated device that 
> disconnects anything else on your line if your modem is active.

CA> Sounds like a handy thing to have, what does RS charge for these?

WC> Mines over seven years old years but when I bought it it was 9.95. 
WC> I was going to make the darn thing it was so simple but by the time 
WC> you bought parts, case, modular plugs, modular plug crimping tool...

Easy enough to take a spare cable,  cut it in half,  and wire it between a
pair of jacks on the wall...

WC> It IS handy and you no-one downline of the device can scramble your
WC> download. If I pick up my phone while the modem's on I get
WC> nothing,] no screech from the modem no nothing.
WC> If someone in the house is prone to eavesdropping they get nothing
WC> on a phone downleg of the device.
WC> Just looked online and the thing is mentioned but I cannot
WC> readily find the price due to lousy page design, lousy
WC> search engine, lack of downloadable PDF catalog and the fact they
WC> were out of catalogs when I was last in there.

I remember a circuit that was *real* simple,  just a couple of transistors
and a small number of discrete parts.  For starters,  you could have it
drive an LED and it'd serve as a "phone-in-use" indicator.  Or
have it drive a relay, and it'd control a tape recorder.  In the case of
what you're talking here,  it just disconnects the stuff upline from there.

I had done some wiring at one point for the phone setup when we had
"the shop",  and would occasionally do modeming in there.  To
prevent me from getting interrupted,  the phones that were tied to that
(second) line were fed the line from the "phone" jack in the back
of the modem -- when it was in use there was no connection there.

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