Easy relaxation oscillator. All you need is three components, plus the power source. Works as LED flasher, tone generator, or AM modulator. Very good web page that goes into detail about this circuit ----- http://www.cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html Related Videos: Neon Lamp Oscillator: https://www.youtube.com/watch?v=Z222teHxi00 Simple AM Transmitter Built on a REAL Breadboard https://www.youtube.com/watch?v=0_OYqAyelHo