Last Updated on March 16, 2024
This is single IC LM3909 variable LED flasher circuit, and it needs only 1.5 volts for operation, we can vary the speed of flasher by varying variable resistor R2.
IC LM3909
The LM3909 is a monolithic oscillator specifically designed to flash Light Emitting Diodes. By using the timing capacitor for voltage boost, it delivers pulses of 2 or more volts to the LED while operating on a supply of 1.5V or less. The circuit is inherently self-starting, and requires addition of only a battery and capacitor to function as an LED flasher.
Circuit Diagram
Components List
| S.No | Name | Quantity |
| 1. | IC LM 3909 | 1 |
| 2. | Battery | 1 |
| 3. | LED green | 1 |
| 4. | Capacitor 350uF/10V | 1 |
| 5. | Resistor 100 Ω Resistor 2.2K Ω Variable Resistor 2.5K Ω |
2 1 1 |
thank you for this circuit. I have had 2 of these ICs over 30 yrs but didn`t know what to do with them.
🙂 Thanks for your interest stay in touch.