Use high frequency out of the piezo speaker and IC-556 is base as oscillator between 22kHz and 56kHz This projects is safer and more convenient.
This is a fast blinking LED bike light circuit For safety when the bike at night. We use two-NPN-PNP transistor oscillator circuit and RC circuit only show on 4 LEDs…
If you want one A lamp flasher circuit using transistors that flashing for general to use. I have many ways, But today you see this three of the lamp flasher circuits.[...]
This is Simple VCO circuit using schmitt trigger using 74HC14__Hex inverting, which inside have 6 schmitt trigger, but applied one frequency controller