This is a very useful and interesting project of a 555 PWM LED dimmer circuit. The circuit can be used to control the brightness of LEDs. The circuit is built around a famous 555 timer IC that is working as a astable multivibrator here. The 50K variable resistor is used to control the brightness of LEDs as desired.
The circuit is using 12 super bright white LEDs. The maximum output of a 555 IC is 200mA due to which it can drive only few LEDs, therefore we have used a BD139 transistor at the IC output that could drive upto 1A current load. If you want to add more LEDs simply connect each three LEDs with a 68 ohms resistor as connected in the circuit diagram. The circuit can handle upto 40 LEDs.

For driving more than 1A current load or more LEDs a higher current output transistor can also be used like TIP31, TIP41 etc. The transistor will dissipate heat during operation therefore it is must to use a suitable heatsink with it.   




 
 

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555 PWM LED Dimmer Circuit Diagram