Transistor oscillator circuit using thermal feedback for oscillation

A monolithic oscillator circuit formed in a silicon chip comprising:

• a comparator element having first and second inputs;
• first and second transistors having similar output characteristics coupled respectively to the first and second inputs of said comparator and having their base regions and emitter regions coupled in common;
• a resistor coupled to the collector region of the first transistor to cause the first and second transistors to be unbalanced so that a potential difference is created at the inputs of the comparator when a potential is applied to the circuit;
• a third transistor coupled to the output of the comparator and placed approximately ten times as far from the second transistor as the first transistor such that heat generated by the third transistor when current passes therethrough will affect the output of the first transistor in order to reduce the potential difference sufficiently to shut off any current from the comparator to the third transistor,
• said circuit thereby producing pulses with a frequency in the range 200 - 10,000 Hz and an average output current of 10-30 mA.