Phone call detector circuit!

This circuit is quit simple, its uses a 555 timer ic set as a monostable multivibrator to prolong the detector circuit output... I have tried it my self and it worked perfectly,, hope you like it!

Parts 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 cell etc.)