We can say that this circuit is equivalent to a unijunction transistor in the relaxation oscillator configuration. The circuit generates a signal in the audio range determined by C1 and set to P1. The supply can be made with voltages from 9 to 12 V and the output consists of short pulses given by the discharge of C1 over R3. This circuit operates only in the audio range and can replace the unijunction transistor in many applications.
