Overview: Simple PWM Lamp Dimmer Circuit using IC 555 Timer
In this project, we will learn about simple and efficient PWM Lamp Dimmer Circuit using IC 555 Timer. We can make the dimmer using the linear regulator IC as well. But the problem with such dimmer is that they can only attain a maximum efficiency of 50%. But the PWM based dimmers can make over 90% efficiency.
Because of such high efficiency the heat loss is minimized. Consequently, the switching elements of PWM dimmers require a smaller heat sink. The small heat sink can reduce the overall device size as well as weight. So, in this article, we will make a 12V PWM lamp dimmer using NE555 IC and a few switching transistors and diode. You can also make Light Dimmer using MOSFET and 555 Timer or a DC Motor Speed Control project based on PWM.
The 555 Timer-based circuit is only valid for DC circuits over a small voltage range. You cannot use this circuit with AC Dimmers. We genrally use TRIAC for AC Dimmer Circuits. You can check our website article to learn more about 555 Timer Based Projects
Bill of Materials
Following are the components required for making this project. All the components can be easily purchased from Amazon.
| S.N. | Components | Description | Quantity |
|---|---|---|---|
| 1 | Resistor | 1K | 3 |
| 2 | Capacitor | 0.01uF Ceramic Disk | 2 |
| 3 | Diode | 1N4007 | 1 |
| 4 | Transistor | 2N2222 | 1 |
| 5 | Transistor | BD139 | 1 |
| 6 | Potentiometerr | 50K | 1 |
| 7 | 555 Timer IC | NE555 | 1 |
| 8 | Bulb | 12V | 1 |
| 9 | Battery | 12V | 1 |
PWM Lamp Dimmer Circuit
The Circuit for PWM Lamp Dimmer using IC 555 Timer is given below.
In the above Circuit, NE555 timer is wired as an astable multivibrator and operates at 2.8KHz frequency. The Resistors R2, R3, POT RV1 & capacitor C2 are the timing components. The duty cycle of the IC’s output can be adjusted using the Potentiometer RV1. The higher the duty cycle the higher the lamp brightness and lower the duty cycle the lower the lamp brightness.
The diode D1, 1N4007 by-passes the lower half of the Potentiometer RV1 during the charging cycle of the astable multivibrator. This is done in order to keep the output frequency constant irrespective of the duty cycle. Transistors Q1 and Q2 form a Darlington driver stage for the 12V lamp. Resistor R1 limits the base current of transistor Q1.
