IWISTAO Low Noise Adjustable Parallel Power Supply for Vacuum Tube Filament No Including Rectifier and Filter

Model No: WHF-PPWPCBK

This is a parallel voltage regulating power supply with current limiting designed specifically for use as a vacuum tube filament power supply. While it is not a precision voltage stabilizing circuit, it is simple and easy to build, and has been popular on DIY websites for a long time. Its noise reduction effect is remarkable, though it requires cooperation with other components. In practice, the circuit produces a clean background and surprisingly clear and powerful low frequency output.

Note that this board does not include the rectifier and filter parts, which must be added separately.

However, the board itself is small, measuring 1.6mm thick with 2oz copper and capable of handling up to 4A current with a sufficiently large radiator.

 
The circuit includes C1, R1, R2, R3, R4, R5, Q1, and Q2, which form the current limiting circuit. R1 determines the maximum flow current, so its resistance calculation is critical. After experimentation, we recommend using the formula R=0.6/(I+0.04), where I is the load current and 0.04A is the current that needs to flow through Q7.

For example, to calculate for a 300B tube with 1.25A, R=0.6/(1.25+0.04)=0.465 ohms. It is important to note that if you turn on the power without plugging in the tube, the full 1.29A will flow through Q7 and it will become very hot. Therefore, it is not recommended to leave the load idle or lightly loaded for extended periods unless your radiator has sufficient cooling capacity.

The output voltage adjustment range is primarily determined by R7, which is a trimmer potentiometer. The resistance value of R7 affects the output voltage range, with smaller resistance values yielding smaller voltage output ranges and vice versa. However, we are available to help with any adjustment issues.

Because the circuit is simple and reliable, we only provide kits with high-quality components, including BC's MRS25 series resistors (excluding R1), appropriately configured capacitors, and genuine transistors. Our careful selection and procurement process saves you time and money. While our prices may not be the lowest, we aim to provide quality and reliability that is worth the investment.