There are many types of emergency vehicle lights that installed on police cars, fire engines, ambulances, etc. This post presents circuit for blinking alternately the two red LEDs and two blue LEDs to imitate the flashing police lights. Circuit is based on two 555 timers which works at different frequency.
Components
| No. | Component | Quantity |
|---|---|---|
| 1. | Power supply (9V) | 1 |
| 2. | 555 timer | 2 |
| 3. | 270Ω resistor | 1 |
| 4. | 1MΩ resistor | 2 |
| 5. | 1μF electrolytic capacitor | 1 |
| 6. | 100μF electrolytic capacitor | 1 |
| 7. | 10nF ceramic capacitor | 2 |
| 8. | 100nF ceramic capacitor | 1 |
| 9. | Red LED | 2 |
| 10. | Blue LED | 2 |
Circuit diagram
The values of R1 resistor and C2 capacitor affects the frequency of switching between red and blue LEDs. The blinking rate of the LEDs is affected by values of R3 resistor and C4 capacitor.
Designed circuit
Circuit is designed on a breadboard.
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