Phone Line Simulator with PIC16F819


Posted on Jan 17, 2013

Creating projects that connect to the phone line can be a real chore without some device like this. It generates the 48 volts DC for the on-hook condition, the 100 volts AC for the ring signal, and the 20 milliamperes DC for the off-hook condition. To use the device, a phone is connected to the left jack. When it is picked up (off-hook), a ring signal is generated at the right jack.


Phone Line Simulator with PIC16F819
Click here to download the full size of the above Circuit.

When the device on that jack goes off-hook, the ring is terminated, 20 ma is provided thru 600 ohms, and the 2 lines are connected for audio. When the phone is hung up, a 250 ms line break is created on the other jack to indicate the end of the phone connection. This allows testing of incomming phone devices only (i.e. answering devices). Here are the Source, Object, and Schmatic files.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

High voltage supply
Inverter circuit diagram
10 led VU Meter using LM3915
zener Flyback diodes issues and pull-in & hold current issues in this Relay circuit
ac measurement status
audio amplifier using ic lm4780
FOUR STATION TWO WAYl
Four-Digit Keypad-Operated Switch
Christmas lights consisting of a circuit diagram of optocoupler



Top