Cut Phone Line Detector

Part Total Qty. Description Substitutions
R1, R2, R3 3 22 Meg 1/4 W Resistor
R4 1 2.2 Meg 1/4 W Resistor
C1 1 0.47uF 250V Mylar Capicitor
Q1 1 2N3904 Transistor 2N2222
Q2 1 2N3906 Transistor
Q3 1 IRF510 Power MOSFET
D1 1 1N914 Diode
Load 1 See "Notes"
MISC 1 Wire, Phone Connectors, Circiut Board


Notes

The "Load" can be a relay, lamp, motor, etc. The circuit can also be connected to a security system to sound an alarm in case the phone line is cut.

If the circuit is connected to a security system or other circuit, both circuits must be electrically isolated from each other using an opto-isolator, relay, etc. This also means that the Cut Phone Line Detector must be powered by a seperate 9V supply