Telephone call meter

[stevan]

Hello folks!
First time here,newbie, sorry if mistake something.

Well, i need PIC based project - fixed telephone call meter,charge meter, billing or whatever you may call it.
Device should have own inteligent LCD. Must count pulses (via 16kHz carrier).
Must display pulses per talk.Must have total pulses per day (or given period) option.Also must have reset to zero option. Would be good to have conversion from counted pulses to price (optional).
Already search the net and didnt find anything even close!?

What i do have, is this....starting point, not much..

 

[Gayan Soyza]

Diagram looks like just a basic ring detector.You cant do anything from it.Ring detectors mostly used to off hook the phone.It means ex:when it detects 3 rings you tell the micro to off hook the phone via a suitable resistor.This is the beginning in your project.

Apart from that what is pulses per talk? You mean DTMF frequency?

 

[stevan]

No. There is 16kHz subcarrier modulated in line signal, AC 5uS, 15V amplitude.
Easy filtered through parallel filter (L1,C3). D1,D2,C4,C5 detects those pulses and conduct T1. T1 shots transduced mechanical counter...and that is all.
This schematic could do the job, only if i need to see pulses per talk.
What i really want here is more "inteligent" control on those pulses.
uPC controlled handling with overall expenses....
Regards!

 

[stevan]

Again sch..

 

[mneary]

@stevan: It is becoming apparent that your telephone system is not like that which the rest of us have.

A detailed description of your system, and your location is mandatory unless you enjoy receiving conflicting information.

 

[petrv]

As far as I know these 16 KHz pulses are used in some European countries to send "metering" pulses that you can count during your phone call and get the price for the call (but multiplying the count with "unit" price charger per each pulse). It is advisory only as a pulse can be missed etc ... It is similar to (Euro-) ISDN supplementary service called "AOC" or "Advice of Charge" which does the same thing (but should be more reliable) over an ISDN line.

Petr

 

[RODALCO]

In The Netherlands, where I originally come from, impulses are sent via the phone lines.
These are square waves of opposite polarity and circuit listed by stevan can detect those.
A counter can be attached and impulses counted for billing purposes.
The impulses are "generated" in the exchange and will be more rapidly on long distance calls.

In New Zealand we get charged per minute or part thereoff after 1 minute for toll calls.
I made a simple circuit to measure the hours we are on line on the internet, and run a normal 12 volts hour meter from it, to keep track of internet time.