SWTPC Digi-Vista Nixie Clock

Top posted for brevity. Most equipment I've worked with run 160-190V for Nixies. Further my Yaesu YC-355D freq counter that I purchased in 1973 is nixie based and also uses around 170V. FYI: base logic is venerable 7490, 7475 and 7441 for the decades. For a simple PS to run nixies (and valves) I use a 6.3V CT 600ma or 1A To 117V mains transformer. They are common here in the USA and cheap. I drive them with a pair of bipolar power transistors in TO220 cases from 12V. Base drive for those transistors is derived from a squarewave source of two phases 180 degrees (555 and 7474 work fine) at 400hz or so (not criticial, higher makes filtering easier and less mechanical hum). The ouput can be rectified and filterd as needed (bridge or doubler is what I do depending on voltages needed). The voltage will be around 210V with a small load (10ma). If I need more power a heavier transformer with 3A or 5A 6.5V winding is used. Also if a stable voltage is needed sample the output and use that as feed back to a series pass feeding primary side power. That will regulate very well. I've built that many times and run many a HV device and even a CRT (D170 size) that required 1200V. For that I used a small 1A 10VCT:230V control transformer and a voltage multiplier and feedback for regulation. Works well. I prefer the driven style rather than self excited voltage converter as it's easier starting and has stable operation. It also doesn't require a special (hard to find or make) multiwinding transformer. the rest of the parts are also generally easily found in defunct stereos or even ratshack. Exotica and unobtainium is a pain. Allison