Friday, 15 July 2016

World's simplest Oscillator / Esaki Oscillator

Reona Esaki (江崎 玲於奈 Esaki Reona, born March 12, 1925), also known as Leo Esaki, is a Japanese physicist who shared theNobel Prize in Physics in 1973 with Ivar Giaever and Brian David Josephson for his discovery of the phenomenon of electron tunneling. He is known for his invention of the Esaki diode, which exploited that phenomenon. This research was done when he was with Tokyo Tsushin Kogyo (now known as Sony). He has also contributed in being a pioneer of the semiconductor superlattices.

Here is the circuit of oscillator he invented
How it Works?

Here the transistor is connected in reverse direction.In this condition no currents flows through the transistor.
But if applied voltage is greater than the breakdown voltage ,current will start flowing. here the voltage across the capacitor does this work. And base of the transistor is left open.
As the capacitor discharges through the transistor and LED the voltage goes down and the transistor goes off and the capacitor again starts charging. Hence the cycle repeats and the circuit works as an oscillator.
By varying the potentiometer position we can vary frequency. 

A video demo