Cut Phone Line Detector

Parts List

R1,R2,R3 = 22M, Resistor
      R4 = 2.2M, Resistor
      C1 = 0.47uF, 250V, Mylar, Capacitor
      D1 = 1N914, NTE519, or other small signal diode
      Q1 = 2N3904, NTE123AP, Transistor
      Q2 = 2N3906, NTE159, Transistor
      Q3 = IRF510, NTE2382, Power MosFet

Description:
This circuit speaks for itself. When the phone line is okay, Q1 acts as a short with a very high ohms value via R1, R2, and R3 for a total of about 66 MegaOhm so very high. When the phone line is cut (open), it activates the MosFet (Q3) via transistor Q2 to drive the load. Substitutes are fine, none of the components are critical.

The 'LOAD' can be anything you like. A relay, motor, lamp, tape-recorder, stereo, security system, or whatever.
Keep in mind that Phone companies don't like to have anything 'directly' connected to their wires for obvious reasons, so use this circuit at your own risk. If you like to play it save use an Opto-Isolator or something...
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