The flasher circuits below operate on a single 1.5 volt battery. LED flasher circuit diagrams. The circuit on the upper uses the popular LM3909 LED flasher IC and requires only a timing capacitor and ...

Resistor R2 restricts current through the UJT as well as LED. At power on, capacitor C2 charges through R1 and when it fully charges, emitter of UJT forward biases and current flows into the base. LED ...