Caller ID Display


Posted on Oct 22, 2012

CallID Unit based on Motorola MC68HC11A1P & MC145447P chips compatible with the standard protocols. if you got a multimeter and a phone you can start testing. Check the voltage across the pair, should be 48VDC in US, 60VDC in Europe. Place a 600 ohm resistor, 5W across the pair and measure the current should be 20 to 40mA (holding current) While on-hook the Ring will have a negative voltage and the Tip will be grounded through equipment at the Central Office UNLESS the office is a `Floating Battery` type office. In the latter case the Ring will have a negative voltage and the Tip will have a positive voltage. The sum of the two voltages (which are in series) will be about 48 to 52 Volts. The usual way of doing this is to use a bicolor LED that glows read with one polarity and green when the polarity is reversed.






Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Capacitor discharge ignition system ( PIC 16F615 )
Sound activated switch circuit
Ac-line-voltage-announcer
Ultrasonic Cleaner Circuit
10 led VU Meter using LM3915
brain wave machine
Novel BuzzerCircuit
Arduino Vocal Effects Box
pulse induction metal detector with DSP
MEM 800
DC exciter excitation mode circuit



Top