PWM LED Dimmer Circuit Diagram using IC 555 Timer May 13, 2015This 1W LED DIMMER is primarily a 555 IC based PWM (Pulse Width Modulation) circuit developed to get variable voltage over constant voltage. The method of PWM is explained below. Before we get start building a 1 Watt LED Dimmer circuit, first consider a simple circuit PWM based LED Dimmer Using 555 - Circuit, Block Diagram Apr 12, 2018Introduction. In this project, we will see a PWM based LED Dimmer using 555 Timer IC. The main principle of this circuit is to generate a Pulse Width Modulation PWM Signal with the help of the good old reliable 555 Timer IC and vary the power being delivered to the LEDs and hence achieving the effect of LED Dimming.