In the circuit diagram, a constant polarity voltage is applied to the G terminal of the PUT via the R1 and R2 voltage divider resistors. The current passing through the resistor (R4) of 100 kW starts to charge the capacitor. If the voltage across the load on C is greater than 0.6 V from the voltage on G, the PUT will pass through the conduction. On R3, a voltage that resembles a sawtooth occurs. The transmission pass level of the PUT can be adjusted (programmable) if the value of the R1 and R2 providing the polarity of the G end is changed.
For example, the pulse generator circuit with PUT works with 12V. If the voltage divider resistors are R1 = R2 = 100 kW. In this case, the poling voltage at the G end of PUT is VG = 6V. Therefore, when the voltage of the capacitor exceeds 6.6 V, PUT starts to generate pulses on R3 by passing through the conduction.