Two Transistor Oscillator

We built a two transistor oscillator which turns transistors ON and OFF all the time. The speed in which it happens depends upon the value of the capacitor. The higher it is the slower is the process of turning ON and OFF.

Transistor Q2 turns on first as there is now a pathway to ground for C1, C1 begins to charge with its right plate being positive and its left plate being negative through R1.

C1’s right plate reaches a threshold where Q1 is turned on. Turning on Q1 gives a pathway to ground to C2, causing C2 to charge through R2 with a positive voltage on its left plate and a negative voltage on its left.

Simulation of the two transistor oscillator in LT spice.



The green wave represents output of Q2 TRANSISTOR at node1 with reference to ground. The red wave represents output of Q1 TRANSISTOR at node2 with reference to ground.