This flasher/beacon circuit can be employed as a distress signal on highways, a direction pointer for parking lots, hospitals, and hotels, etc. The circuit uses a power LED, and provides more light than a typical incandescent lamp flasher. Use of a 6V or 12V SLA lantern battery makes the circuit portable.
The heart of the circuit is an MC34063 monolithic switching regulator subsystem, originally intended for use in DC-DC converters. This device contains a voltage reference, comparator, controlled duty cycle oscillator with an active peak current limit circuit, driver, and a high current output switch, all in an 8-pin DIP.
The circuit briefly flashes a 1W power LED from a 6V to 12V DC supply – at about 5% duty-cycle. Current limiting to the LED is accomplished by monitoring the voltage drop across R1, a 1Ω sense resistor placed between VCC and the output switch, pin 1.
For more detail: HB-LED flashing beacon repurposes switching regulator