Ringing Phone Light Flasher

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

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.