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How to build Ringing Phone Light Flasher
November 30, 2010 - category: Miscellaneous telephone
I have received several emails asking how to connect up some lights so that when the phone rings, they flash. This is very useful in a situation were there is lots of noise and it is impossable to hear the phone, such as a workshop. Here is such a device. The ring detect part of this circuit came from
http://www.hut.fi/Misc/Electronics/circuits/telephone_ringer.html
Circuit diagram
Parts:
- C1 0.47uF 250V Capacitor
- R1, R2 10K 1/4 W Resistor
- R3 1K 1/4W Resistor
- D1, D2 20V 1/4W Zener Diode
- D3 1N4148 Diode
- Q1 2N3904 NPN Transistor or 2N2222
- U1 4N27 Opto Isolator
- RELAY Solid State Or Regular Relay (See Notes)
- MISC Case, Wire, Board
Notes:
- You may need to use a lower voltage zener for D1 and D2.
- You can use a regular relay instead of a solid state relay, but the arcing accross the contacts may destroy it pretty quickly.
- Be very sure that you have not accidentally connected 120V to the phone line when building and installing this circuit.
circuit from http://www.aaroncake.net/
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