How to Make a Simple LED Dimmer Using 555 Timer

A better way to control the brightness of led without using a micro-controller. 

A Microcontroller needs programming to do this task but not everybody likes to code. Microcontrollers are not cheap as well, so here is the solution. The 555 timer ic. It is easy to use and inexpensive can be used in an amazing no of applications. 

For eg. Flashing LEDs, a tone generator circuit like a siren. 

We need, 

• BREADBOARD
• 100 Ω RESISTOR 
• 500 KΩ POT
• 2 CERAMIC CAPACITOR (1NF AND 10NF)
• 2 RECTIFIER DIODE (1N4007)
• LED’s 
• 555 TIMER IC AND 5V POWER SUPPLY

We charge the capacitor through r1, d1 & r2 and discharge it through r2 & d2. 

The on and off time is decided by the time taken by its capacitor to charge and discharge through resistors. 

As we slide the pot wiper we are controlling the charging and discharging time of the capacitor so we can easily vary the duty cycle of the PWM Signal. 

In this configuration the period is one cycle thus the frequency will always be the same 

R1 resistance is much smaller than the resistance of the pot. In that way, we have 99% control over the charging and discharging resistance in the circuit.

As an output at pin 3, we get a PWM signal, which controls the brightness of the led.