Dwight, The circuit board portion is easy, but the bit inside of the black box is a bit more complex. While I originally thought that it might be an integral HV supply of some sort, I now have additional information which says otherwise. Interestingly enough, that info originated from Tony Duel. Here it is: HP made a decade counter/display board where the counter FFs were made from pairs of transistors in the conventional way (8 transistors on the board). These were controlled with diodes to count in 1242 (not 1248) BCD code.

The outputs of these counters drove 8 neon bulbs, and by varying the bias applied, the state of the counter could be latched in the bulbs (that's why this is relevant here). These bulbs were mounted inside a plastic block on the PCB, and shone onto a think-flim circuit of CdS photoresistors. These were connected to form a binary to decimal decoder to drive a nixie tube. --tom At 02:37 PM 5/20/2003 -0700, you wrote: > >From: "Tom Uban" <uban(a)ubanproductions.com> > > > >Hello, > > > >Probably my best find at the recent Hamvention in Dayton OH was a > >stack of nixie tube modules made by HP. In retrospect, I wish that > >I had purchased the whole box of them, but I hopefully have enough > >to at least make a clock. > > > >I have two variations on the modules, the part numbers are: > > HP 05212-6016 series 648 > > HP 05212-6003 series 415 > >They both use Borroughs B422 nixie tubes and look like they may have > >an integrated HV supply of some sort. > >Hi > I don't see anything that I'd call a power supply. The >transistors look like they might be flops/latches or buffers to >drive the nixies. If you don't find some schematics, you >could hand draw some. I doubt that it would be too hard to >follow. >Dwight > > > > > >Here are a couple of pics for reference: > > > >http://www.ubanproductions.com/Images/nixie1.jpg > >http://www.ubanproductions.com/Images/nixie2.jpg > > > >I would appreciate if anyone can tell me what HP (or other) instruments > >may have used these modules. I would also like to find a schematic of > >the module if possible. > > > >Thanks! > > > >--tom

Dwight, The circuit board portion is easy, but the bit inside of the black box is a bit more complex. While I originally thought that it might be an integral HV supply of some sort, I now have additional information which says otherwise. Interestingly enough, that info originated from Tony Duel. Here it is: