Police Car Lights circuit

This square wave is damped by IC1b and in turn drives decade counter IC2. The outputs of the counter Q0/Q2 and Q7/Q9 are diode ORed turn to alternating double pulses.

C2 and C3 with R5 and R3 differ pulse time in conjunction with the output drivers and IC1C IC1F. This produces a short pulse (30 ms) increases the effect of flash and adds to the illusion. Output drivers turn drive a pair of blue leds hyperbright D5 and D6.

It's worth spending a little more on using really bright leds if the best effect is to be obtained. A camera battery 6 V or four AAA cells gives a long life in a small package. In use adjust VR1 to give the best effect