Those B-7971 tubes cost between $10 and $12 at the time, which was 2000, 2001. There was an Ebay seller who sent them wrapped in newspaper. OLD newspaper from 1968, 1970 era! I bought up a nice stock of them and sockets. The plan at the time was that since my B-7971 display system is of modular construction, and since each module is a group of 8 tubes, the initial construction was for (2) of these modules. I got enough tubes and sockets to make a 3rd module, so that the readout array would be 24 tubes wide! But that 3rd module has not yet been made. Stocked up on enough tubes to have plenty for a 24 tube array, plus several spares. In the recent reactivation of this project, this time I did a complete teardown of the scrolling logic. That logic was on (2) 3220 point solderless boards and it was never very good, it was highly experimental, a prototype just to get things working.
Everything is slowly being tested carefully, piece by piece as it slowly goes back together again. It is driven from an old ancient Radio Shack ASCII keyboard kit. That kit has 19 old old plain 74XX series TTL. That keyboard draws 300 milliamps just by itself! Those (32) 74LS273 ICs on the tube driver cards draw another 500 mA. I am seriously thinking of changing out those "LS" series chips with 74HC versions. Much less current. What do you guys think of that idea? On Sunday, May 26, 2024 at 9:31:04 AM UTC-4 Jim KO5V wrote: > > That's great! I remember seeing a picture or video that display - or one > very much like it. > > I bought most of my B-7971 tubes between 2002 and maybe 2005, and I think > I paid $20-$30 each. A seller who seemed to have a LOT of them, would put > them into the shipping box in their original styrofoam packaging, which had > been broken broken up into sections, and then add random broken styrofoam > pieces as filler. It was sloppy and lazy, and you could hear things moving > around inside of the box. They didn't seem to care because there were > plenty of tubes to go around. I received one broken tube, and they replaced > it, but I think I had to pay the additional shipping cost. > > I think that's about the time I started following this list. It was when > Ray was running it. > > BTW, I actually received my Geekklock kit from him, but I never got the > "Accessory Module". Many people got nothing. His design seemed to be pretty > good, and the kit was very nicely done. It must have turned into a pyramid > scheme where he was paying the old debts with money from current sales, so > eventually there was no capitol to buy parts, and it finally imploded. The > situation was very sad. > > Several years ago, I started simplifying my life a bit, and I sold some > spare tubes that had been gathering dust for years. Then, my MOD 6 clock > was involved in a remodeling accident (covered here when I was looking for > some replacement tubes). Fortunately, I was able to replace them for just a > bit more than my selling price because members of this list took pity on my > poor clock! > > Jim > On Saturday, May 25, 2024 at 6:27:48 PM UTC-6 gregebert wrote: > >> How much were 7971's selling-for back in 2001, or whenever you got them ? >> Today I see them around 200 USD; I paid 80 USD back in 2017 when I built >> my 8-tube clock. >> Long ago, as in the 1970's, I think PolyPaks was selling surplus 2-tube >> modules for 8 USD. >> >> On Saturday, May 25, 2024 at 11:01:41 AM UTC-7 Leroy Jones wrote: >> >>> Here's another. >>> >>> On Saturday, May 25, 2024 at 2:00:00 PM UTC-4 Leroy Jones wrote: >>> >>>> Built this in 2001. Each tube has its own driver card. Each card >>>> contains (2) 74LS273 8-bit latches. MPSA42 transistors switch each >>>> segment via 30k anode resistors. >>>> 74LS273 outputs operate transistor base via 100k resistor. 15 of 16 >>>> bits used for tube. >>>> There is one extra unused bit. >>>> >>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/90206707-eccf-460a-bc88-dbcc1d9d81c0n%40googlegroups.com.
