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.
Part list
R1____________100K 1/4W Resistor R2______________3K9 1/4W Resistor R3______________1M 1/4W Resistor C1,C2_________100nF 63V Polyester Capacitors C3____________220µF 25V Electrolytic Capacitor D1______________LED Red 10mm. Ultra-bright (see Notes) D2___________1N5819 40V 1A Schottky-barrier Diode (see Notes) Q1____________BC547 45V 100mA NPN Transistor IC1____________7555 or TS555CN CMos Timer IC L1_____________Sensor coil (see Notes) B1_____________1.5V Battery (AA or AAA)
LED se pali ako se ne varam na 1.7 V, posto je u kolu timer oscilacije koje proizvodi na
elektrolitskim kond podici ce napon za sqrt(2) sto je nekih 2.12 V. ispravite me ako negdje
grijesim...
IP: 91.191.27.102 IP: 91.191.27.102
Ovo je zanimljivo, samo - mene kopka jedna cinjenica. Svi znamo da LED-ica radi na oko 2 do 2,5
V a napajanje je ovdje 1,5 V . . . ???
IP: 194.0.84.50 IP: 194.0.84.50