Radio Shack ASCII keyboard ?? Is that the one that doesn't have a RETURN key (gotta use CTRL-M), but it does have a linefeed key ? I built a video terminal with that in high school and was thrilled I could use a 300 baud connection.
Switching to 74HC should reduce your power. I recall there was one "oddball" 74XX IC that wasn't sold by RS, and they included it in the keyboard kit. Glad to hear you have a nice stock of tubes and plan to use them. On Sunday, May 26, 2024 at 7:13:55 AM UTC-7 Leroy Jones wrote: > 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/e9b0202f-483c-40c6-809d-28f5e41d01f0n%40googlegroups.com.
