Transistor reverse breakdown voltage tester circuit diagram

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This paper introduces a small instrument that can measure the reverse breakdown voltage of a transistor by using a common universal meter. The measurement range is 0-1000V, which can meet the general measurement requirements.
1. Circuit Principle The circuit of the transistor reverse breakdown voltage tester is shown in the figure below.
The circuit can be regarded as a high-voltage constant current source to feed the tube to be tested, and the reverse breakdown voltage of the tube can be directly read by a multimeter. The circuit is essentially a feedback DC converter that converts a 3V DC voltage to a main high voltage DC of around 1200V. After the circuit is energized, due to the coupling feedback between the windings N1 and N2 of the transformer T, the circuit is strongly oscillated, and the oscillating voltage is boosted by the winding N3, which is rectified by VD2 and charged to the capacitor c2 so that both ends of C2 can be obtained. 1200v DC high voltage. The high voltage is applied to the tube to be tested by a high-value resistor R2 to cause the tube to break down, and the multimeter connected to both ends of the tube to be tested can directly read the reverse breakdown voltage of the tube. Since the R2 resistance value is large, it acts as a constant current source, and the current is small at the time of breakdown, and the tube to be tested is not damaged.