The LED flasher or blinking circuit is a simple and low budget electronic project. This circuit makes the LED light to blink at a specific time intervals. This type of LED flasher circuits are often used in visual indicators, alarm systems and decorative lighting. This project demonstrates build an LED flasher using the LM3909 IC. The LM3909 IC is a low power LED flasher and oscillator IC designed for a single 1.5v battery or DC supply.
Components Required
To build this LED flasher circuit, you will need the following electronic components and other parts are listed below,
- IC LM3909 – LED flasher/oscillator IC.
- Capacitor (C1) – 100 µF, 16V electrolytic capacitor.
- LED (LED1) – Standard red LED (any color).
- Battery (B1) – 1.5V AA size alkaline battery.
LED Flasher Circuit Diagram
The circuit diagram is shown above. It uses a minimal number of electronic components and it is am ideal project for beginners in electronics. The LM3909 IC simplifies the design by integrating the timing and switching functions necessary to flash the LED.
Working Principle
The LM3909 IC works as a low power oscillator and LED driver. The capacitor C1 100uf/16v is charges and discharges periodically through the internal circuitry, this process is controlling the flashing rate of the connected LED.
When the DC power is applied, the capacitor begins to charge through internal resistors in the IC. Once the capacitor reaches a specific voltage threshold, the IC starts to discharges it rapidly through the LED. When discharging the current through LED makes it glow at specific time which causing it to flash. This process repeats continuously and creating a blinking effect.
The flashing rate of the LED is depending on the value of Capacitor “C1”, a higher capacitance will result in a slower blinking rate and lower capacitance value will make the LED flash faster.
Power Supply for LED Flasher circuit
The flasher circuit operates on a 1.5V DC power source, such as a single AA sized alkaline battery. low voltage is not an issue, the LM3909 IC can still drive an LED effectively by using a built in voltage booster circuit inside the IC to provide sufficient current to the LED for illumination.
Applications
- LED indicators and alarms
- Toy and decoration lights
- Portable signal lights
- Low power beacons
