On this small (4x4 in), extra thick (0.094 in) PCB with 2 oz-copper traces resides both a simple high-voltage power supply and a low-voltage power supply and low-voltage regulator, with each finding its own raw power supply, including the rectifiers and power-supply reservoir capacitors.
The low-voltage regulator is meant to power the tube heaters; the high-voltage power supply, the rest of the tube circuit. The low-voltage regulatorís power supply is flexible enough to allow either a conventional full-wave-bridge and full-wave center-tapped rectifier arrangement or a two-rectifier voltage-doubler configuration, allowing for more latitude in power transformer selection; this regulator can be set to either 6.3V or 12V or 12.6V.
Just like the PS-5, the high-voltage portion of the PS-4 power supply uses a tube rectifier, a simple RC filter to achieve a fairly quiet B+ voltage, which can span from 200V to 380V.
It is not the equal to the Janus regulator, but then it is neither as expensive nor complex; in addition, it is much more flexible, as it can use any suitable series resistor value in its RC filter, whereas the Janus must use a 1500-ohm resistor.
In other words, add a power transformer and the PS-4 PCB makes the basis of a fine tube-circuit power supply, say a tube line-stage amplifier or headphone amplifier or crossover or, even, a small power amplifier.
Many topologies, such as the Aikido and Broskie and White cathode followers or cascode or Aikido topology, use triodes standing atop one another, which makes referencing the heater power supply to the B+ power supply a small chore. With one tube atop another and a single heater power supply, the top and bottom heaters cannot share the same heater-to-cathode voltage relationships. With such totem circuits, the safest path is to reference the heater power supply to a voltage equal to one-fourth the B+ voltage; for example, 75V, when using a 300V power supply. Referencing the heaters to 1/4th of the B-plus voltage ensures that both top and bottom triodes see the same magnitude of heater-to-cathode voltage. The easiest way to establish this voltage relationship is to attach the heater winding's center-tap to the "Heater Ref." pad on the PCB. If the heater winding does not offer a center-tap, then place two 1k resistors in series across the winding and attach the junction between both resistors to the pad labeled "Heater Ref." on the PCB.
Kit includes user guide, PCB, all capacitors and resistors, and four standoffs, with O-rings and screws. Tube rectifiers that can be used are 5AR4/GZ34 or 5R4 or 5Y3 or WE274B can be used. Does not include power transformer.