Joseph Fenn wrote:

I often am on the internet when my wife picks up the telephone upstairs
thus breaking my connection to the ISP. Does anyone have a circuit
or know of a source for and "offline" indicators what will flash an LED
or something so the wife will know I am useing the internet downstairs??
Joe/KH6JF


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Most "proper" phones can be connected in a "chain". The main phone, when off
hook, automatically disconnects the later part of the "chained" phones.

Most modern modems have this function as well.

When the XYL lifts unhooks the phone, there would just be a dead line as
long as the modem is online.

It's possible that the Taiwanese Wal-Mart brands doesn't include this option
and if it is so, you can easily build a chain by adding a small relay that
disconnects the other phones in the house as soon as the modem line
consumes any current. Remember that the line impedance should be around 600
Ohms.

This is a simple piece of design, just place a small resistor in series with
the modem, drive a small mosfet with the voltage drop over the resistor and
trip a small relay. I don't know your line voltage in the US but I'd assume
it's 48Volts, so a 48Volt modem should be dirt cheap as it's telephone
standard. If you wanna do it a bit more fancy without the relay, use a pin
diode to cut your dear lady off... It's even cheaper!


Cheers

Dan / M0DFI