Cellular Phone calling Detector


Posted on Mar 16, 2013

This circuit was designed to detect when a call is incoming in a cellular phone (even when the calling tone of the device is switched-off) by means of a flashing LED. The device must be placed a few centimeters from the cellular phone, so its sensor coil L1 can detect the field emitted by the phone receiver during an incoming call. The signal detected by the sensor coil is amplified by transistor Q1 and drives the monostable input pin of IC1. The IC`s output voltage is doubled by C2 & D2 in order to drive the high-efficiency ultra-bright LED at a suitable peak-voltage. # Stand-by current drawing is less than 200µA, therefore a power on/off switch is unnecessary. Sensitivity of this circuit depends on the sensor coil type. L1 can be made by winding 130 to 150 turns of 0.2 mm. enameled wire on a 5 cm. diameter former (e.g. a can).


Cellular Phone calling Detector
Click here to download the full size of the above Circuit.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Optical-ttl-coupler
Guild Country Belle Telephone Radio (1956)
RGB LED experiment Arduino
McCoy Mighty Midget Transmitter
optocouplers safely isolate integrated power modules
oscillator
Simple Infrared Control Extender
Double tube fluorescent emergency circuit 2
Simple adjustment of high input impedance double wave linear detection circuit RC4558DN



Top