0-300V Variable High Voltage Power Supply

[guclusat]

Here is the variable high voltage dc power supply circuit which we can customize the output voltagefrom 0 to 311Vdc, and it is protected the current over limit that we define at about 100 mA.

In the circuit you can see the T1 is a mains transformer with a ratio of 1:1, for security reasons , and reduces noise signal as well. Then the mains voltage from the T1 is rectified to DCvolt with bridge diode D1-D4, We use a No. 1N4007 that withstand voltage as 1,000V at the current 1A and and this DCV is filtered through the capacitor C1 – 220uF 400V be the big size electrolytic types, by the voltage drop across C1 is about 311VDC.


The power MOSFET Q1 is controlled the current output, with using the resistor R3 – 500K adjust the voltage gate pin of Q1. The ZENER diode ZD1-12V is available prevent over voltage at gate pin of the Q2 if we not has it when high volt the Q2 may be damaged.


The transistor Q2-BC337 and the shunt resistor R2 – 3.3ohm are added for as a current limiter. When the current output is too increased, the Q2 will stop the gate pin of the Q1 immediately, which will be guard the higher current output. The degree of R3 gets from testing in this circuit, which depending on the gain of the transistor or the hFE value, so you may need to tune the value of R2


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[uydudoktoru]

0-300V Variable Voltage, Current Transformerless Power Supply Circuit

The post explains a simple transformerless zero to 300 volts variable voltage and current power supply circuit which can be used for many different applications.

To protect against my higher voltage research projects from shooting up in smoke permanently, I developed an easy circuit which is able to render a variable voltage supply of 0 to 330 Volt. But please be cautioned, the circuit is not isolated from mains potential, and therefore can inflict a lethal shock.

The supply is short-circuit proof: the current is restricted to approximately 100mA.

Circuit description

The design does not require a transformer, rather a 100 watt bulb is introduced at the input in order to provide ultimate safety in case of a short circuit or a component failure.

The mains voltage from after passing through the lamp is rectified with bridge D1 (1Amp / 500V) and C1.

T1 is configured as a source follower: the source of T1 complies with the voltage of the wiper of R3. D2 is insured to safeguard the gate of T1.

T2 and shunt resistor R2 establish the current limiter. Whenever the output current results in being excessive, T2 quickly discharges the gate of T1. This stops the current from increasing any further. The value of R3 was basically identified experimentally; however it actually depends on the Hfe of T2 which means you may need to adjust the value of R2 appropriately.

Keep in mind T1 requires a large heatsink: in nastiest situation T1 would probably disperse 330V x 100mA = 33Watt!
You may try mosfets such as a BUZ 326 (400V/10.5Amp) or you may likewise use an IRF740 (400V/10Amp).
The output impedance of the power supply varies according to the beta of T1, therefore the bigger the MOSFET, the lesser the output impedance!