police car lights schematic

Police Car Lights with LEDs

british police lightsThis circuit is used to simulate the police car lights by alternating flashing strobes seen on British police cars. The IC1a forms a square wave oscillator having adjustable frequency with VR1 to give the best effect.

This square wave is buffered by IC1b and in turn drives the decade counter IC2. Outputs from the counter Q0/Q2 and Q7/Q9 are in turn diode ORed to give alternating double pulses.
C2 and C3 with R3 and R5 differentiate the pulse time in conjuction with the output drivers IC1c and IC1f. This produces a short pulse (30 ms) which enhances the flashing effect and adds to the illusion. The output drivers in turn drive a pair of hyperbright blue leds D5 and D6.

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

Article sent by Ian Johnson (Sw) at, thanks.

Police Car Lights circuit diagram

police car lights schematic


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  • rendra

    this schematic for 5v , how about 12v for motorcycle or car ?? the ic blow or not ?

  • oeduardf

    hello, im using 12volts, what parts should i need to change…thanks
    more power to you


    i really enjoy your diagrams and some of the comments made by others this your website is a good one keep on i still need one thing from and i will be very happy if u help me with the diagram. i need a diagram for an a.v.r that can be used in a generator of 160 kva please i will be very graetfull to have the diagram from u i know u will have it thanks. MARTIN WRITING FROM CAMEROON.

  • Mark Sutton

    We have a small office in the city and the electricity bill is insane. Tell you what, we have tried to turn off the all the electric juice sucking machines, but not really see much of the difference in the bills. But, one day our plaza electrician told me that they are changing all the LED light tubes outside the plaza. Those LED lights look the same as the old light tube but after that we don’t think we see the electrician for months until people complaint about other problems. We tried using the LED light tubes and we are so damn glad we did. We already have the electric bill saving to pay off the LED lights that we got. Awesome product!!!

  • Scott

    Okay… we are not all learned souls. Some of us would love the foil patterns for these great ideas!