This is a small size led flasher built with the 555 timer IC that is powered from 2 x 1.5V batteries. The circuit can be used as a flashing metronome, dark room timer, memo-reminder or other similar ...

[4dcircuitry]’s 555-based flashing circuit sculpture ticks all the go-for-it boxen for us — the component list is short, the final circuit looks cool, and well, there are blinkenlights.

The flasher is the standard 555 oscillator circuit that drives an ultrabright white LED for daylight visibility. Repetition rate is about 2hZ and the duty cycle is about 10%. Peak LED current is 60mA, ...

Inside, two 555s are set up as basic flasher circuits, each feeding a vactrol – essentially a resistive optoisolater. Inside is an LED, which is optically coupled to a light-dependent resistor.