Telephone Ring Count

Hi,

I found the circuit attached that suppose to detect when a phone is ringing and the number of times the phone rings...The part of the circuit which has "to counter"...is that going to the PIC microcontroller or something?...Which pin would it need to be connected to on the PIC18F452?...Or is there another chip which determines ring count seperately from the 4N25? I completely lost

The 'to counter' output would go to the PIC.

The "device" is simply an opto-coupler. The counting has to be done via a sub-routine in the microcontroller.

In my Infinity Bug, it detects the phone ring via a diode and resistor network (simply the zener of a 1N4148). You know the length of a ring so you just create a time-delay of a few seconds and count the number of time-delays.

colin55 said:

The "device" is simply an opto-coupler. The counting has to be done via a sub-routine in the microcontroller.

In my Infinity Bug, it detects the phone ring via a diode and resistor network (simply the zener of a 1N4148). You know the length of a ring so you just create a time-delay of a few seconds and count the number of time-delays.

Click to expand...

The length of ring tone present varies from country to country, so I would detect start of ring and sample until ring = 0 for several samples, then ring count is incremented.

Ring detect/count

thanks mike...that's a great idea because i'm from Trinidad & Tobago and don't know the duration of a typical ring in my country. Everytime i call the company that deals with the phone service they tell me hold to speak to a technician and no one ever comes to speak to me. What is the duration of a ring in the United States of a typical DTMF-2500 telephone handset?...Anyone familiar with this?...I think that is the same telephone set used here in Trinidad.