Vintage RS 7 Seg PCB - Page 1
Forum section: electronics / beginners

author: Supernaut
author_rank: Contributor
timestamp: July 03, 2024, 06:22:48 pm
content: I recently received a batch of vintage electronic components in a job lot, it has two of these RS 7 segment controllers but I cant find any information or pictures online. Has anyone ever dealt with one of these before? Im guessing its from the 1970's at least, would be curious to know if it could be used.

author: jbeng
author_rank: Regular Contributor
timestamp: July 03, 2024, 07:18:17 pm
content: Based on the components on the boards, these appear to be counter/display boards. I can't tell by the photo what type of displays those are, but they appear to be incandescent 7-segment devices, sometimes called "Numitrons". You should be able to see lamp-type filaments arranged in a 7-segment configuration inside the tubes to verify this.Since the ICs are 7400-series TTL, (7490=decade counters, 7447=7-segment display drivers - 1972-73 vintage based on the device date codes) they will run on 5 volts only. If the displays are numitron type, they will also likely run on 5 volts... more than that and you may damage the displays and/or the electronics.

author: Supernaut
author_rank: Contributor
timestamp: July 03, 2024, 10:39:03 pm
content: It is indeed! I just powered it with a variable power supply and kept it below 5v, sure enough it pops up with a number 6 on the valve. Ive never seen one of these before so i wasn't sure what to expect, i knew it would deal with numerical LED's but i didn't expect the valve itself to have the numbers in it.Thanks very much for your response

author: Kim Christensen
author_rank: Super Contributor
timestamp: July 03, 2024, 11:00:12 pm
content: As is, they could be cascaded as a simple counter.If the white jumpers were removed, the 7475 installed, then these cards could be used in a frequency counter with a bit of additional logic. Looks like they were meant to plug into a mother board as individual digits in a counter of some sort.But it's old power hungry tech. So unless you're into the nostalgia of it, there's not much use for them.

author: floobydust
author_rank: Super Contributor
timestamp: July 03, 2024, 11:26:45 pm
content: What part numbers are on the display tubes?

author: Supernaut
author_rank: Contributor
timestamp: July 04, 2024, 12:02:33 am
content: The full name/number on the glass is;RS7-SEGIND58-635-2F7421Thanks for the replies so far!

author: retiredfeline
author_rank: Frequent Contributor
timestamp: July 04, 2024, 01:40:17 am
content: The 7475 is a 4 bit latch so I think that the inclusion of that will allow the counter output to be held.

author: floobydust
author_rank: Super Contributor
timestamp: July 05, 2024, 07:23:52 pm
content: Most of the date codes are 1974 and I couldn't find any RS related info.The display tubes are RS house-numbered which seems even more rare. I thought RCADR2100etc. were the only players back then but the internals look different, not sure what make OP's are.

author: CaptDon
author_rank: Super Contributor
timestamp: July 07, 2024, 04:41:40 pm
content: I don't remember Radio Shack having that P.C.B. available but back in their hayday they had many kits available including complete ascii keyboards and such and most of the stuff was handled also through Allied Electronics in their catalog. Radio Shack had a lot of cool stuff in the early to latte 70's. Some of the kits were digital clocks and I believe a 6 digit frequency counter using the 40 pin LSI chips. I really miss the old RS stores which were Tandy franchises. I did a lot of saddle making and repairs of the old McClelland civil war saddles for the re-enactors and I was often buying supplies at the Tandy Leather Store in Duncannon Pa. along the Susquehanna River.

author: floobydust
author_rank: Super Contributor
timestamp: July 07, 2024, 05:24:29 pm
content: It's not Radio Shack- but I think RS Electronics in the UK.I was trying to work backwards from the display tube manufacturer, I can find only RCA did the Numitron.If you need to cry, here's a good placehttps://www.radioshackcatalogs.com

author: CaptDon
author_rank: Super Contributor
timestamp: July 07, 2024, 05:43:12 pm
content: Ahh, I was unfamiliar with RS Electronics from the U.K. I will look into their history.

author: Gyro
author_rank: Super Contributor
timestamp: July 07, 2024, 05:47:40 pm
content: Quote from: Kim Christensen on July 03, 2024, 11:00:12 pmActually, not that power hungry for a sunlight readable display. The Minitron 3015F Numitron consumes 8mA / segment (those are probably similar), not that dissimilar from a sunlight readable LED display. Replace the 74 series chips with 74HC and they wouldn't be that bad. Those displays were used extensively in fuel pumps for their life, readability and temperature range (down to -50'C) until relatively recently. 7 segment LCDs have pretty much taken over in fuel pumps now (but they were also available back then). I would be surprised if the LCD panels don't include some low level heating even now.

author: factory
author_rank: Super Contributor
timestamp: July 07, 2024, 05:56:49 pm
content: It's RS Components in the UK, originally known as Radiospares.I've only got a couple of old RS catalogs, the oldest from 1984 has ready made blank PCBs for building a 8 digit LED based universal counter and many other things, someone on here might have an older catalog with information;https://www.vintage-radio.net/forum/index.phpThe hard bit would be finding the RS datasheets to go with them, we had slightly more recent folders of these at work, but no-one was allowed to rescue or buy anything and they are now long gone.David

author: factory
author_rank: Super Contributor
timestamp: July 07, 2024, 06:01:03 pm
content: Quote from: Gyro on July 07, 2024, 05:47:40 pmActually some were still in use at a small independent garage near me this year, sadly the garage closed last month after the owner passed away.David

author: factory
author_rank: Super Contributor
timestamp: July 07, 2024, 06:25:20 pm
content: RS 58-635-2 was made in Japan, possibly by Apollo.David

author: nfmax
author_rank: Super Contributor
timestamp: July 07, 2024, 06:34:27 pm
content: I remember those! The Radiospares catalogue used to be a thin A4 magazine type thing, before growing into a phone book sized boxed set, after which it was online only. Originally, R/S sold spare parts to the radio & TV repair trade, and were very touchy about who could open an account with them, later on they opened up and now they’re a general full service broadline distributor.The decade PCBs date to the early stages of the transition. You could make a counter using them, or most people used them to make clocks. The really adventurous could make a DVM, even!

author: Supernaut
author_rank: Contributor
timestamp: July 07, 2024, 06:56:05 pm
content: Happy to see so many responses, got a bit more attention that i anticipated. For the curious ive taken a few backlit photos and a clear top down photo of the PCB so you can get a better idea of what's going on. I have two of these but currently no use for them so it would be interesting to know what people would do with these if they had them.

author: factory
author_rank: Super Contributor
timestamp: July 07, 2024, 06:56:22 pm
content: Quote from: nfmax on July 07, 2024, 06:34:27 pmI've only seen the decade display boards appear on their own, yet to find something that got built with them in such as a counter or DVM.One of the other RS kit boards I remember was the 8038 based function gen board, these were used in some custom built test boxes at work, one of which had four of them.David

author: themadhippy
author_rank: Super Contributor
timestamp: July 07, 2024, 07:20:30 pm
content: QuoteThey did have a separate company in the 70's that sold to the hobbiest,the name escapes me at the moment.Quotecount the number of times people point at them and ask "whats that for?"

author: Kim Christensen
author_rank: Super Contributor
timestamp: July 07, 2024, 07:40:18 pm
content: Quote from: Supernaut on July 07, 2024, 06:56:05 pmI'd probably just sell them on e-bay or something since I'd only have two digits to play with.But, if I was into model rocketry, they might make a cool count down display for the igniter.

author: Supernaut
author_rank: Contributor
timestamp: July 07, 2024, 08:59:34 pm
content: Quotecount the number of times people point at them and ask "whats that for?"I only have two or three visitors to my house so i could tally that number up quite quicklyQuote from: Kim Christensen on July 07, 2024, 07:40:18 pmI might sell them but the whole batch of vintage electronics only cost me £13.50 so they don't really owe me much, if i find more of them it increases my chances of building something if i just hold on to the two i have already.Il see how it goes