N5ESE's
145 Volt Regulated Power Supply for Tube Circuits
(click on any picture to see larger version)
(click on any picture to see larger version)
| NOTE: 'N5FC' is my former call. This project was constructed while that call was valid, and you may observe references to it. |
I've been wanting to homebrew some tube equipment for some time. When it comes to power supplies for homebrew gear, solid state projects can often get away with a 9 volt battery... not so with tubes. I wanted a power supply that would serve to power a QRP tube transmitter (like my Altoobs rig), or a two or three tube receiver. This little power supply will serve both. I also wanted it compact, and at 5.5 x 4 x 3.5 inches, I think I succeeded.
The circuit utilizes a fullwave rectifier following a small (15VA) 115V:115V isolation transformer. After some RC filtering, we have about 165 VDC with moderate ripple. A simple but effective solid-state regulator circuit, utilizing two sweep-amplifier transistors, reduces ripple to less than 0.1 %, and provides about 145 VDC regulated output at up to 75 mA. Load regulation (no load to full load) seems to be around 2.5%. This should make an excellent supply for our cathode-keyed transmitter (the regulation should help minimize key clicks), and be quite adequate for a simple tube-based receiver.
And of course, we have another transformer capable of supplying 12 or 6.3 VAC at up to 1 amp, for filaments.
Here's a crude working schematic of the power supply:
(click on the image above for a larger, semi-clearer version)
The PC boards were constructed using the "cut-and-peel" method, whereby one uses a hobby knife to renmove unwanted copper, and form islands.
Here are some more images, showing various construction details:
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