Universal Power Supply 

 

 

 

 

 

The Raleigh Audio High Voltage Power Supply has been designed with a lot of versatility to accommodate a wide range of requirements for the DIY hobbyist.  It features vacuum tube rectification, a vacuum tube shunt regulated B+ supply, AC filament supply, and a regulated 12vDC supply. As frosting on the cake, an input mains power line noise filter is included.  Applications are too numerous to list here, so contact us and discuss your specific requirements.  

High Voltage Section 

An innovative power supply kit designed using the concept of "Minimal Reactance,"  draws from the classic tube power supply designs while incorporating modern technology not available to the designers of yesteryear. The result is a marriage of the smoothness of a tube rectifier with the precision of a MOSFET current source that gives an incredibly clean and transparent sonic presentation. Only film capacitors are used in the high-voltage section, eliminating the sonic footprint of electrolytic capacitors. This supply is so clean and transparent that you could hear the grunge contributed by generic resistors if they had been used. Careful listening evaluation resulted in the use of Caddock and Kiwame resistors critically chosen to achieve sonic excellence. 

Although the basic design is a Minimal Reactance power supply, it may be used a regulated supply following a standard capacitance input or choke input filter. The output voltage of the regulator is adjustable with a range depending on the the input AC voltage, the type of input filter (MR, capacitor, choke) and the type of regulator tube used.  The current through the constant current source is adjustable and the pass current of the shunt regulator depends upon the type of tube used in the regulator. The board has been laid out to accommodate a much larger heatsink if required. 

Low Voltage Section 

The output voltage is adjustable and the board is laid out to accommodate larger diodes and heatsink so the current capability can be extended to 2A. Although the low voltage is usually referenced to the high voltage ground, there is a provision to bias the low voltage above ground. This is useful if the low voltage supply were used as a regulated DC filament supply.  

Delay features

There are two delay circuits in this power supply: a B+ delay and output mute. The use of these delay circuits is optional and the delay times are adjustable. Each delay circuit has a set of relay contact which may be used to control external functions. 

Noise Considerations 

Provisions have been made in the design of this power supply to minimize the effect of external power line noise and internally generated noise. A power line filter is provided for external noise. Several things have been done to minimize internally generated noise. A vacuum tube is used for the high voltage rectifier, and Schottky diodes are used for the low voltage rectifier. An additional filter is placed on the input to the low voltage supply to isolate the two supplies. Both the high voltage and low voltage sections are Minimal Reactance designs which minimizes ringing in the transformer. For further information on the Minimal Reactance Power Supply concept, see Chapter 5 in the series of line stage articles.

Size  4.5 inches by 6.1 inches

To support this power supply, you need to separately provide an input power connector with fuse, a power-on switch, and a power transformer. The transformer should provide  two 250VAC windings (500VAC CT) at 70mA, 6.3VAC @ 2.4A and 17VAC at 200mA. The Lundahl LL1683 is recommended.

115VAC or 220VAC wiring is accommodated by the LL1683.

 

Here is the schematic diagram of this high voltage power supply.