Solid State Valve Power Supply Project         All photos copyright John Mills, last updated 27 Dec 2009 A solid state valve power supply ?? Well actually not a solid state valve, but a power supply for testing valves and valve circuits using modern solid state devices. This is not meant to be a definitive construction project, but I hope that sharing my recent construction, testing, "blowing up", modifying and final design project that this may be of help to others who may want to construct something similar. I am more than happy to help with any questions on these pages, please feel free to email me with questions. In line with modern times let me stress that the high voltages and circuitry used here are lethal if handled incorrectly, and I cannot be held liable in any way for any injuries or death that may occur if the user does not have knowledge required for handling such devices.   I based my design around a little known (in the UK) high voltage regulator by Supertex called the LR8N3. This is a TO92 plastic packaged device that can provide a variable output from 1.2v to 440v. You can download the PDF data sheet Here As this will only allow a min of 10mA output current it does have to supplemented with a pass transistor, which will allow over 100mA to be sourced. More of the choice of pass device later !!   My concept was to design a twin 100mA output unit, giving a variable output from approx 60v up to 350v, along with common preset points of 90v, 105v, 150v, 200v, 250v, 300v & 350v. I also wanted a lower current supply to offer a negative grid bias voltage up to approx 25v, for future use as a valve characteristic tester. No heater supplies have been incorporated, due simply to the lack of available space in my metal case, but I already possess various variable DC supplies capable of this task, along with a few assorted "heater" transformers in any event. Select the three additional menu options on the left to open new pages detailing the design.