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

Light-Wave Voice-Communication Transmitter Circuit
F232 is USB powered
Parts and schematic for an AM radio transmitter
Door lock Motor
ic lm338 application circuits explained
vu meter
Simple MD Catridge Preamplifier
9-Line Telephone Sharer
TWH9205 by the integrated circuit consisting of a temperature control circuit automatically
555 zinc-manganese batteries reduction charger circuit
Touch fan speed control circuit eight stalls
Simple fourth gear dimmer switch circuit