Light Flasher

This circuits uses 555 Ic for flashing... The Flashing speed is also controllable using the trimpot..

555 IC Pin config :

Knight Rider Scanner Circuit

This in not the exact circuit for the knight rider circuit. Just make some modifications.. You can make the light flash in any sequence. I have installed this circuit in my car..

LED Photo Sensor

Here's a circuit that takes advantage of the photo-voltaic voltage of an ordinary LED. The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with a gain of about 20. This produces a change of about 5 volts at the output from darkness to bright light. The 100K potentiometer can be set so that the output is around 7 volts in darkness and falls to about 2 volts in bright light.