flashers

Flashers are devices that generate intermittent light pulses or signals. They function as a simple, self-contained means of attracting attention or indicating state, and are found in automotive, signaling, and photographic equipment. The term can describe a range of technologies, from electromechanical relays to modern solid-state circuits.

Two main categories are thermal (electromechanical) flashers and electronic flashers. Thermal flashers rely on a metal bimetal strip that heats when current flows; when the strip bends, it opens the circuit, the strip cools, and the circuit closes again, producing a regular blink. Electronic flashers use transistors or integrated circuits to switch the lamp on and off at a fixed rate, independent of simple heating. Electronic types include load-sensing features to accommodate different bulb types.

Automotive use: In most vehicles, a flasher relay controls the turn signals and hazard lights. The relay alternately completes and breaks the circuit to the indicator lamps, creating the familiar clicking and blinking. Modern cars may integrate the flasher function into a body control module, and LED or low-current bulbs can require resistors or smart flashers to maintain correct flash rates.

Other applications include photography and signaling. In photography, flashers or flash controllers coordinate short light pulses for metering, synchronization with camera shutters, or triggering external strobes. In safety and signaling systems, flashing beacons and warning lamps use flasher circuits to produce conspicuous rhythmic light.

History and development: Early flashers were electromechanical and relied on thermal effects. With the advent of solid-state electronics, electronic flashers became common, offering greater reliability and precise timing. Variants exist for different voltages and lighting loads, and continued evolution includes compatibility features for LED lighting and smart control systems.