Homemade economical high-voltage power supply for measurement

During repair work, electronic enthusiasts sometimes need to measure the withstand voltage of damping tubes, output tubes and other high-voltage devices, which require a high-voltage power supply. The high-voltage power supply introduced in this article does not require a transformer and can be made for only 2-3 yuan. It is very suitable for electronic enthusiasts who often do repairs. The circuit is shown below. D1, D2, C1, and C3 form a voltage doubler rectifier circuit; D3, D4, C2, and C4 form another half-wave voltage doubler rectifier circuit with opposite polarity. After the two circuits are combined, it can output -275V, -550V, and -1100V high voltage. Since no isolation transformer is used, for safety reasons, a live wire indicator that can be touched by hand is set up so that the end connected to the switch is always the live wire. When using it, first turn on the power and touch the copper sheet with your hand. If the neon light is on, it can be used. R2 is a current-limiting resistor used to protect the meter. The full-scale current of the meter is 0.1mA. It can also be replaced by the current range of a multimeter. The diode withstand voltage should be greater than 600V, and there is no current requirement. The capacitors C1 and C2 are 0.22μ with a withstand voltage of 250V, and the capacitors C3 and C4 are 0.22μ with a withstand voltage of 630V.