Police lights

479

03:16:50

    This is the normal police red-blue LED flash.
                   OPERATION:
         In this circuit the brightness of the blue LEDs is controlled by the capacitor by the left(100uF).At values less than 76.4uF the blue LEDs flicker and break.Also the 100uF capacitor affects only the blue LEDs and nothing else in the whole circuit which makes it very unique.The 2.2uF capacitor is used as a form of backup for the 100uF capacitor(in case of failure).
     The diodes reduce the risk of current fall back from the components of the circuit(555 timers, transistors and the loads).
    Due to the unavailability of an audio outlet(speaker) in EveryCircuit there's no siren sound in this circuit.But in real application when building this circuit connect the speaker in parallel with the PNP bipolar transistor by the right.

published 11 years ago

Bootsy7718

10 years ago

I'm building one of these for my 3 year old daughter's pretend police car. Just browsing different schematics. There isn't a way to run both the lights and siren off the same two timers? Only in my first year ceet and not sure but I think it's called cascading or something.

Ericampire

10 years ago

nice work

Ifoegbu1

10 years ago

Thanks guys

Jalaj

10 years ago

You don't need such a complicated circuit for police lights.....you could configure 555 as astable multivibrator with 50% duty cycle

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