Guest liquibyte Posted December 8, 2014 Report Share Posted December 8, 2014 I've done some preliminary work converting the Power Designs 2020B schematic in Eagle. The parts aren't right for their values for the most part but this is an attempt at making a legible schematic and not a board. I worked off of the parts list and the schematic in the service manual and have discovered discrepancies. There are parts listed in the parts list that aren't on the schematic and there are parts on the schematic that aren't in the parts list. There are also values that are listed that differ between the two. I haven't read through the manual itself to see if there were changes etc. so I don't know if this is talked about. The transistors, op amps, and voltage reference are unobtainium so substitutes will have to be looked for. I've found references to replacements for some of the transistors to be 2N1700 and 2N3773 but haven't worked on the op amps or voltage reference (total unobtainium) yet. These supplies had hand picked matched parts so even a real world build would probably only be an approximation to the reported still in calibration after 30 years. The plan is to try and find modern replacements, model this, and finally do a test build to see if a good hobby supply could be had based on this. I'm only posting this for informational value at this point in the hopes it might generate a discussion of how to approach building one. The concept is solid and these are much sought after so a modern equivalent seems to me to be a good idea.PD-2020.zip Quote Link to comment Share on other sites More sharing options...
Hero999 Posted December 8, 2014 Report Share Posted December 8, 2014 Here's the schematic, inverted and converted to monochrome to make it more clear. Quote Link to comment Share on other sites More sharing options...
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