Police Strobe Light Effect Circuit

A Police Strobe Light Chaser Circuit is an electronic circuit designed to mimic the flashing red and blue lights used on police vehicles. It alternately flashes groups of LEDs (commonly red and blue) in a strobe or chasing pattern, creating a visually dynamic effect similar to real police beacons.

Components Used:

• 555 Timer IC
• Red LED
• Blue LED
• 10uf Capacitor
• 104 Capacitor
• 680k Resistor
• 100k Resistor
• 1k Resistor
• 68R Resistor

Special Thanks to Our Sponser – JLCPCB:

No project is complete without the right tool and materials. That’s why our sponser JLCPCB stepped into provide essential material for the project. JLCPCB is a leading provider of high quality printed circuit board and PCB assembling services.

Simply head over to JLCPCB, Upload your gerber file, select specification and just place your order.

48-Hour Turnaround for 6 Layer PCBs!

$0 for 2u” ENIG. Free Via-in-Pad. High Precision. Sign Up to Get $80 New User Coupons.

How To Order PCB

Gerber File:

Basic Definition

The 555 Timer IC is a small electronic chip that can produce accurate time delays or square wave signals.
It can operate in three main modes:

1. Monostable mode – produces a single pulse when triggered.
2. Astable mode – generates a continuous stream of pulses (like a clock).
3. Bistable mode – works like a flip-flop, having two stable states (ON and OFF).

Pin Configuration (8 Pins)

Pin No.	Name	Function
1	GND	Connected to ground (0V).
2	Trigger	Starts the timing interval when voltage drops below 1/3 of supply.
3	Output	Provides the output signal (HIGH or LOW).
4	Reset	Resets the timer when pulled LOW.
5	Control Voltage	Used to adjust threshold voltage (usually connected to ground via a capacitor).
6	Threshold	Ends the timing when voltage reaches 2/3 of supply.
7	Discharge	Discharges the timing capacitor to restart the cycle.
8	VCC	Power supply (+4.5V to +15V).

Internal Structure

Inside the 555 timer are:

• Two comparators (compare voltages),
• One flip-flop (stores ON/OFF state),
• One discharge transistor, and
• Voltage divider made of 3 resistors (each 5kΩ — that’s where “555” comes from).

Operating Modes

1. Astable Mode

• No stable state (it continuously switches between HIGH and LOW).
• Used for generating clock pulses, LED blinkers, or tone generation.

2. Monostable Mode

• Has one stable state (LOW).
• Produces a single output pulse when triggered.
• Used in timers, pulse width control, and delay circuits.

3. Bistable Mode

• Two stable states — can be set or reset manually.
• Used in flip-flop, switch debouncing, or memory applications.

Applications

• LED Flasher / Blinker
• Police light chaser
• Pulse generator
• Delay timer
• PWM (Pulse Width Modulation) controller
• Tone generator (for sound circuits)

More Projects