Do you want to build a simple LED flasher which powering from 3V? In this article i’m sharing the circuit diagram, components list and working principle of 3 Volt Led Flasher Circuit using BC547 and BC557 transistors. Whether you’re learning electronics or need a blinking LED circuit for your DIY projects this given circuit is a great place to start.
Components Required
| Component | Value | Quantity | Description |
|---|---|---|---|
| Resistor (R1) | 1 kΩ | 1 | Limits current to the base of Q1 |
| Resistor (R2) | 100 kΩ | 1 | Pull-up resistor, timing part |
| Resistor (R3) | 47 Ω | 1 | Limits emitter current of Q1 |
| Resistor (R4) | 10 kΩ | 1 | Base resistor for Q2 |
| Capacitor (C1) | 10 nF | 1 | Timing capacitor for feedback |
| Capacitor (C2) | 10 µF / 16V | 1 | Coupling/timing capacitor for Q1 |
| Capacitor (C3) | 100 µF / 16V | 1 | Controls blink duration |
| Transistor Q1 | BC547 (NPN) | 1 | Switching transistor |
| Transistor Q2 | BC557 (PNP) | 1 | Switching transistor |
| LED (LED1) | 5mm or 3mm LED | 1 | Flashes ON and OFF |
| Battery (B1) | 3V Battery | 1 | Power supply (e.g., 2×AA or coin cell) |
Circuit Diagram
Working Principle
The basing working principle of this 3V LED flasher circuit is continuous on and off of switching transistors, which will makes the LED lights turn on and off. This circuit consist of 3V battery and few electronics components including transistors, resistors and capacitors.
When you connecting the 3V battery to the circuit the capacitors start to charge and transistor BC547 and BC557 working together and on and off each others which will creating a flip flo action in the circuit.
The connected capacitor C2 and C3 discharging slowly, so this will creates the LED flashing instead of direct turn off. This cycle of flash, off, flash, off continuous. Resistors like R1, R2, and R4 help limit the current and set the speed of the blinking by working with the capacitors.
Applications
- Battery Status Indicator
- Flashing lights to toys to make them more engaging
- Decorative Lighting
- Simple Alarm or Alert System
- Low Power Flashing Beacon project
