Telephone Voice Mail Alert Circuit


Posted on Feb 18, 2013

The cireiilt is built around a couple of low-cost ICs: an H11C4 optoisolator/coupler with an SCR output (Ul) and an LM3909 LED flasher (U2). It is connected to the phone line in the same manner as any extension phone. A ring signal on the telephone activates the opt,oisolator/SCR. and causes U2 to flash LED1.


Telephone Voice Mail Alert Circuit
Click here to download the full size of the above Circuit.

This flash signifies that a ring signal has been received.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Transistor Checker Circuit
5V power supply with overvoltage protection
The HiFi amplifier 300B
Medical call with lighting signal receiver circuit diagram
Zero volt switching circuit diagrams
By DC variable speed motor control circuit diagram of an optical fiber
A variable frequency oscillating circuit transistor



Top