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.
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.
|1.||IC LM 3909||1|
|5.||Resistor 100 Ω
Resistor 2.2K Ω
Variable Resistor 2.5K Ω