Detecting a ringing phone

Anybody ever detect a ringing phone into a PLC?

well one way to go about it is to buy one of those external ringers. they usually have a 120 volt output to trigger a buzzer. then you could tie that into a relay which would then go to a input.

Normally, I have seen a diode bridge connected across the phone line. When the ring is on you have a DC voltage at the output, use this voltage to turn on a relay or other device, or better than that, buy a external ringer as suggested by diat150.

Normal telephone line voltage is -48VDC to Earth. To make a phone ring a 90V 20Hz AC signal is superimposed on the line. Maybe you could use an AC voltage limit relay.

http://www.actionio.com/action/actionpak/limit-alarms/ap168090/

it is depending on the telephone system.
when old and the voltage is 48 volts or alike just use a relais coil and a capacitor. (the capacitor is used to block the DC signal when telephone is in rest.

TConnolly said:

Normal telephone line voltage is -48VDC to Earth. To make a phone ring a 90V 20Hz AC signal is superimposed on the line. Maybe you could use an AC voltage limit relay.

http://www.actionio.com/action/actionpak/limit-alarms/ap168090/

Click to expand...

Sidenote: As a teen I was the guy who could add phone lines and hook up car stereos, fix stuff in general. I always stripped little wires with my teeth. I could get your tunes up and running in minutes this way. I was adding three phones to a friend's house on day, and the j-box was way up high so I worked it hot, as usual with phones.

Dmn him for being so popular, because unlucky for me the phone in the other room rang just as I bit into the wrong wire. I nearly spit my fillings out. It had never shocked me before as long as I was pretty well insulated from earth but the phone had never rang at that instant either! Yes, I still strip itty bitty wires with my teeth, but only if I can hold both ends in my hands.

As soon as you mentioned stripping wires with your teeth I knew where that story was going.

I can share the same experience with you. Certainly a game changing moment for me. On later day I was quickly stripping a wire with my front teeth when a broke off half of A tooth. Although fixed now with some fancy filler I have regret this moment for many years. LOL...

Thanks guys. FYI best thing for stripping little wires: Alligator clips.

TConnolly said:

As soon as you mentioned stripping wires with your teeth I knew where that story was going.

Click to expand...

+1

Stu....