Ringing Phone Light Flasher
Category: Main page » Telephone

Ringing Phone Light Flasher

Source: http://www.aaroncake.net/

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.

Schematic


Schematic for phone flasher

Parts:


Part

Total Qty.

Description

Substitutions

C1

1

0.47uF 250V Capacitor

R1, R2

2

10K 1/4 W Resistor

R3

1

1K 1/4W Resistor

D1, D2

2

20V 1/4W Zener Diode

D3

1

1N4148 Diode

Q1

1

2N3904 NPN Transistor

2N2222

U1

1

4N27 Opto Isolator

RELAY

1

Solid State Or Regular Relay (See Notes)

MISC

1

Case, Wire, Board

Notes:

1. You may need to use a lower voltage zener for D1 and D2.

2. You can use a regular relay instead of a solid state relay, but the arcing accross the contacts may destroy it pretty quickly.

3. Be very sure that you have not accidentally connected 120V to the phone line when building and installing this circuit.


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