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How to make a police flasher on a relay

You can make a very simple LED police flasher yourself in about 15 minutes. There are no microcircuits or transistors in it. Even someone who is very vaguely familiar with electronics can assemble this circuit.
A flashing light will be used as a master oscillator. Light-emitting diode, it is connected in series with the relay and periodically serves as an on and off switch. The closed and open relay contacts are loaded with blue and red LEDs.

Will need


  • Red and blue super bright LEDs 3 pieces each -
  • Flashing Light-emitting diode -
  • Resistors 22 - 100 Ohm - 2 pieces.
  • Capacitor 1000 uF.
  • 12V relay.

Like a police flasher on a relay


Let's take it LEDs and form their output.
How to make a police flasher on a relay

We solder three pieces into a line in series. Solder a resistor to the line.
How to make a police flasher on a relay

In total, you need to assemble two such circuits of LEDs. Red on one side, blue on the other.
How to make a police flasher on a relay

Solder to the relay. One LED pin is adjacent to both the relay contact and its coil.
How to make a police flasher on a relay

Next, solder the power wire to the middle terminal from the contacts and solder the capacitor.
How to make a police flasher on a relay

We solder another line of LEDs to only one contact.
How to make a police flasher on a relay

Take a flashing LED and solder it.
How to make a police flasher on a relay

We connect wire segments from the terminals of the second line. The negative terminal comes from the connection of all LEDs.
How to make a police flasher on a relay

The flasher is ready. Connect to 12 V power supply.
How to make a police flasher on a relay

The light effect is amazing, you can see this for yourself by watching the video below.
How to make a police flasher on a relay

Watch the video


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Comments (2)
  1. Sergey K
    #1 Sergey K Visitors 21 February 2021 23:36
    7
    There was a case where I made a flashing light for the stand on the relay. We tested it, everything blinks cool, we hung up the stand, and this is where the ambush came in - in the 80s it was quite difficult to find documentation and the life time of the relay could only be determined in practice. And at 1Hz, a relay with silver contacts lasts for a day at best. verified. It’s good that there was stock and the exhibition was only three days. But my day began with re-soldering the relay to a new one ;)
    Well, the circuit itself was based on a two-transistor multivibrator.
  2. Max
    #2 Max Guests 17 February 2022 18:02
    3
    I assembled the flasher according to your diagram. For some reason only the blinking light comes on Light-emitting diode.

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