Cut Phone Line Detector 1

Published:2013/7/25 20:53:00 Author:muriel | Keyword: Cut Phone Line, Detector | From:SeekIC

A while ago I got an email asking for the schematic of a circuit to detect cut phone lines. It didn't take me long to find this circuit in Electronics Now. When the circuit detects that a phone line has been cut, it activates a MOSFET which can be used to drive a relay, motor, etc. It can also be connected to a security system. PartsR1, R2, R3 22 Meg 1/4 W ResistorR4 2.2 Meg 1/4 W ResistorC1 0.47uF 250V Mylar CapicitorQ1 2N3904 Transistor or 2N2222Q2 2N3906 TransistorQ3 IRF510 Power MOSFETD1 1N914 DiodeLoad See Notes MISC Wire, Phone Connectors, Circiut Board Notes1. 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.2. 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.



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