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Showing posts from December, 2011

Variable DC Power Supply 3-24V / 3A

This is the variable DC power supply circuit. This power supply has regulated output, can be adjusted from 3 to 25 volts and the current output is limited to 2 amps as shown, however it may possibly be improved up to 3 amps or more by applying a smaller current sense resistor (0.3 ohm). Voltage regulation is controlled by 1/2 of a 1558 or 1458 op-amp. The 1458 may be substituted in the circuit, but it is suggested the supply voltage to pin 8 be limited to 30 VDC, which can be achieved by adding a 6.2 volt zener or 5.1 K resistor in series with pin 8. The 2N3055 and 2N3053 transistors need to be attached on proper heatsinks and the current sense resistor must be rated at 3 watts minimum.

600V Power Supply for QRO HF Amplifiers

Here the schematic design diagram of 600V power supply for QRO HF amplifiers. Amateur Radio Transmitters working with valves such as 807 or1625 operates properly using a plate voltage in between 600V to 700 Volts. The circuit described below is actually a full wave voltage doubler. The output voltage is twice the input voltage. For 230V AC input the output is going to be close to 600 Volts.


Resister R1 is applied to minimize the initial high voltage and high currents. Capacitor C1, C2, C3 along with coils L1 and L2 form input line filter. The capacitors C4 and C5 protects diodes from high voltage transients on the AC line as well as minimizes inter carrier hum modulation of the R.F picked up by the mains. Capacitors C6 and C7 gives sufficient filtering for the output DC Voltage.