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

Digital Clock with 6 nixies
100Khz crystal calibrator
Random timer circuit using a Attiny24A
Bicycle Sensing
remote control for electrical
build good audio buffer
LA3430 VCO Non-adjusting Multi-PLL For FM Car Radios
Self-powered Fast Battery-Testers
I have a 315bl excavator. Engine intermittently shut off on
Electro Harmonix drum sequencer
DC Motor Control circuit
Boombox circuit diagram



Top