555 Timer: Police Lights
This project sets up two flashing LEDs, one red and one blue, to create a police lights effect. You can use this circuit to integrate into a toy, or just to practice your circuit building skills. The circuit is built around a 555 timer in astable mode.
The Circuit
R1, R2, and C1 sets the flashing speed of the circuit. With the values chosen below, the lights will switch between colors about 7 times per second. Use the 555 Timer Calculator to choose different values if you want it to flash faster or slower.
Parts List
Battery
9V
C1
1µF
D1
Red
D2
Blue
R1
1k
R2
100k
R3
470
R4
470
U1
555 Timer
The Layout
Here's how you can connect this circuit on a breadboard. For permanent circuits, I recommend soldering it up on a stripboard or perfboard.
