The circuit control lamp brightness with PWM.
It is good for adjusting incandescent lamp light.
It uses 555 timer as astable multivibrator to control low-power lamp.
PWM controls power to lamp and changes brightness easily.
This PWM Based Lamp Brightness Controller Circuit runs on 6V battery and works for many lighting needs.
Circuit Working:
Parts List:
| Component | Value/Type | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | ||
| 10k | 1 | |
| 47k | 1 | |
| 1.5k | 1 | |
| Potentiometer 470k | 1 | |
| Capacitors | ||
| Ceramic 22nF | 1 | |
| Electrolytic 100µF 25V | 1 | |
| Semiconductors | ||
| IC 555 Timer | 1 | |
| Transistor BD681 | 1 | |
| Diode 1N4148 | 2 | |
| Switch ON/OFF | 1 | |
| Lamp Incandescent 6V / 200 mA | 1 | |
| Battery 6V | 1 |
Circuit uses IC 555 in astable mode to make PWM signal.
PWM controls brightness of incandescent lamp.
R1, R2, VR1 and C1 set oscillation speed.
D1, D2 make uneven duty cycle so brightness changes by adjusting R2.
PWM from pin 3 drives transistor Q1 which controls lamp current.
C2 keeps power supply stable.
Change R2 which changes duty cycle and also changes lamp brightness.
Formulas with Calculations:
Formulas for PWM lamp controller with 555 timer:
TON = 0.693 × R1 × C1
TOFF = 0.693 × R2 × C1
Frequency = 1 / (TON + TOFF)
Duty Cycle (%) = (TON / (TON + TOFF)) × 100
Change R2 which will change TOFF and this will change duty cycle with change in lamp brightness.
How to Build:
To build a PWM Based Lamp Brightness Controller Circuit following steps are required for connections of the circuit.
- Assemble all parts as per circuit diagram.
- Pin 1 of IC 555 goes to GND.
- Pin 2 and pin 6 connect together.
- Pin 3 connects to base of Q1 via R3.
- Pin 4 and pin 8 connects to positive supply.
- R1 goes from pin 7 to positive supply.
- C1 goes from pin 2 to GND.
- D1 and D2 connects in series from pin 7.
- Cathode of D1 goes to one end of VR1 and anode of D1 goes to pin 7.
- Cathode of D2 connects to pin 7, anode of D2 goes to one end of R2 and other end of R2 goes to VR1.
- Emitter of Q1 goes to GND.
- Collector of Q1 connects to one end of lamp and other end of lamp goes to positive supply.
- On/Off switch goes between positive supply and +6V battery and battery negative goes to GND.
- C2 goes to positive supply and negative goes to GND.
Conclusion:
PWM Based Lamp Brightness Controller Circuit is for low power use.
Change R2 it changes duty cycle and adjust brightness.
Circuit is good for small lighting, saves energy while keeping right light level.