How CERN made circuit boards in the 1970s - Page 1
Forum section: electronics / general

author: duckduck
author_rank: Frequent Contributor
timestamp: June 13, 2020, 03:22:56 pm
content: Interesting. I wish the author went into more detail. My favorite line:Quotehttps://photos.google.com/share/AF1QipNjVlcaYM4Fre6F_AGtX6Jw0K1BIylWILAPAXds9WwPalniCJwPFOX5v8h1T-CtoQ?key=OVBmbGlwa2dXUXg1a2JBUnpvYWotNVB6cUdyTkVR

author: unitedatoms
author_rank: Frequent Contributor
timestamp: June 13, 2020, 04:09:19 pm
content: Proves the fact that buses, interfaces, protocols and connectors live much longer than individual products.It looks like a Kamak bus / formfactor for crates and racks.We, as community owe the world the mechanical open hardware formfactor for miniature metal enclosure with power supply, backplane and firmware protocols, fire safety, mass produced at low cost to allow home made designs to be incrementally done at hobby's pace.

author: glentek
author_rank: Regular Contributor
timestamp: June 21, 2020, 12:05:16 am
content: This is how I designed PCBs in the 70s and into the 80s. We used red and blue tapes for double sided. Working over a light box in summer was horrible, sweating from the heat of the light bulbs. Very tedious work, especially when you had to literally rip up tracks when you made a modification.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 21, 2020, 12:32:24 am
content: You really had to know your stuff at a detail level back in the day... almost art, as much as science...

author: TerraHertz
author_rank: Super Contributor
timestamp: June 21, 2020, 02:21:49 am
content: Nice photos. It's interesting that the boards shown use what look like carbon composition resistors, which drift high and out of tolerance with age. Makes it kind of surprising they were still operational."They were pieces of opaque adhesive tape, which was cut and meticulously applied to the foil by spatulae."Actually the word you are after is scalpel. Various types used, but a small surgical scalpel with angled straight blade was best. The tape came in rolls. You'd stick down one end, run the trace by rubbing it down with a finger in the path you wanted, then cut the end-point with the scalpel. Pads came on backing sheets, and you'd use the scalpel point to lift one off the sheet, then place it down on the layout. With the scalpel under just one edge of the pad so you had a clear view of the grid sheet through the pad hole. The grid sheet was placed under the clear film used for the layout. The precision, stable, grid sheets were _very_ expensive. Typically the layout would be done at 4x final size, but you still used an optical loupe for best accuracy in tight spots.Surprising to see that the pads and tapes are not falling off by now. The glue fails with age.It's amusing the guy crossing off circuit diagram nodes and components as he laid the traces, didn't use any of that newfangled highlighter pen technology. Good old reliable pencil, that you can trust.With all-new, computerized networked control systems at CERN, it will be interesting to see how long it takes some joker to sneak in stuxnet or whatever.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 21, 2020, 02:58:04 am
content: Along with Disco music, bell bottoms and long sideburns, these hand-drawn schematics and board layouts are what I miss from the 70s.I graduated as an EE in 1978. So in my first job and the following, we were using the exact same design tools. And by tools I mean templates, tape, light boxes, and a sharp knife.What is missing from the photos are the blueprints which were used as the working documents by the engineers and technicians, stamped with red letters: NON-CONTROLLED DOCUMENT.The originals were always kept locked.

author: ebastler
author_rank: Super Contributor
timestamp: June 21, 2020, 06:52:35 am
content: Quote from: TerraHertz on June 21, 2020, 02:21:49 amI think the author did indeed mean "spatula" -- not for the cutting step, but to be used instead of a finger (finder?) when placing and rubbing down the trace.

author: TerraHertz
author_rank: Super Contributor
timestamp: June 21, 2020, 08:56:11 am
content: Quote from: ebastler on June 21, 2020, 06:52:35 amBut then you'd be perpetually swapping back and forth between the blade and spatula. You need the blade for every single run of tape, since it has to be cut off neatly. Holding the roll in one hand, you can use the blade to pick the tape end off the roll (can't touch the sticky side with fingers!), place the starting end precisely, then gently position the tape as you proceed along. When done just run a finger or fingernail along it to fix it firmly. Never putting the scalpel down.A smooth, blunt tool was used for transferring Letraset text though.

author: cgroen
author_rank: Unknown
timestamp: June 21, 2020, 10:18:47 am
content: Quote from: TerraHertz on June 21, 2020, 08:56:11 amThat was exactly how I did it in the 80's! We did the layouts in 2:1. Those were the times....

author: SilverSolder
author_rank: Super Contributor
timestamp: June 21, 2020, 11:19:06 am
content: Art...But, in fairness, what we do on computers today is art too... the tools have changed, is all. There is something satisfying about working by hand, though.

author: PKTKS
author_rank: Super Contributor
timestamp: June 21, 2020, 11:27:57 am
content: Quote from: SilverSolder on June 21, 2020, 11:19:06 amAgreed.If the COVID19 isolation gets me too bored...I still have some left overs from that times...I will have a very good nostalgic time by justdoing schema on paper and making my boardall by hand...Paul

author: SilverSolder
author_rank: Super Contributor
timestamp: June 21, 2020, 12:11:08 pm
content: Quote from: PKTKS on June 21, 2020, 11:27:57 amVery good! :-) I go out in the garden and get stuck in when I feel like that.Working with a computer can sometimes feel like you are using training wheels on a bicycle even if you know how to ride...

author: PlainName
author_rank: Super Contributor
timestamp: June 21, 2020, 04:43:07 pm
content: QuoteProcesses have changed. When I did manual layouts like that, every board was checked by two people, preferably neither of whom had done the schematic or layout. One person would call out a pin on the schematic and the other would trace that on the layout and say what else it was connected to.The first person then ticked off the connections (maybe that's what the schematic in the photos show - not the layout persons reference but the checker's). At the end, there should be no unticked pins on the schematic and, of course, any wrong connections would be picked up during checking.No-one does that now because the ERC is infallible. A bonus of the manual checking was that every detail of the layout was covered so incorrect footprints or things in the wrong place would likely be picked up too.I think it's pretty different. Perhaps a similar thing is writing a book: doing it when a typewriter was state of the art vs a word processor now. And accessibility - anyone can write and publish a book, just as anyone can design and make a PCB, but back then you really had to be 'in the trade' to get anywhere (or even know how it's done).

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: June 22, 2020, 01:21:21 am
content: Quote from: cgroen on June 21, 2020, 10:18:47 amI oversaw this exact procedure during the 70's - 80's in a small video manufacturing outfit. We had just acquired a white printer to get check prints from schematics. To make production documentation so the assemblers could see what part went where on the boards, I found that a paper print of the pcb could be made by spreading a D-size sheet of printer paper on a table (or on the floor if there was no clear table space) sensitive-side up and pinning the two-colour pcb artwork on it. After about 30 min the artwork was put away and the paper was fed through the printer, processing it with ammonia. The blue side (which was always the solder side at our place) would mostly fade away due to the high green light content of the fluorescent lights but the red component side would be printed in high contrast. Then I would just mark it up with coloured markers andvoila'. It was a lot faster than getting a draughtsman to do up a pretty drawing of the board.I will never forget that experience.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 22, 2020, 02:18:30 pm
content: The smell of ammonia and other chemicals in the print room?Indeed, one could smell a print job waaaay down the corridor.

author: Berni
author_rank: Super Contributor
timestamp: June 22, 2020, 02:58:58 pm
content: What is even more impressive are the hand layout boards in consumer electronics from back then. They offten have every last cm2 squezed out of the layout. That is hard work on big complex boards even in CAD, so i can't even imagine how that was like back then. They had no way to easily move paet of the design over by a few mm just to squeze a extra trace or two trough there. Rip it all up

author: SilverSolder
author_rank: Super Contributor
timestamp: June 22, 2020, 03:17:18 pm
content: Quote from: Berni on June 22, 2020, 02:58:58 pmYou might do several generations of draft layouts using pencil and rubber eraser, before attacking the Letraset kit? Then you could use a light board to lay the actual traces.

author: TimFox
author_rank: Super Contributor
timestamp: June 22, 2020, 03:17:41 pm
content: One important detail about hand-taped PCB layouts is that they were done on precision-gridded Mylar substrate material (Bishop Graphics was one source). From about 40 years ago, before computer drafting was common, I remember a problem when a PCB layout on Mylar and a mechanical layout done on Clearprint drafting vellum were combined: the Clearprint material was not intended for precision applications and the total error over about 20 inches caused the mounting holes not to line up.

author: gdewitte
author_rank: Unknown
timestamp: June 22, 2020, 03:27:03 pm
content: I remember CAMAC: often fondly translated as "Committee to Arrange a Meeting in Another City"Quote from: unitedatoms on June 13, 2020, 04:09:19 pm

author: Labrat101
author_rank: Unknown
timestamp: June 22, 2020, 06:57:19 pm
content: wow nice pictures .You could almost smell the old dust on those prints .Thanks brings back a few memories . we also had to make our own boards .Those old boards need to be put away for the future to remind Humans that things can be built to last by skilled hands.Great Minds that had nothing more than a pencil and a slide rule. .As you said ''No lets Google it. ''I still have my engineering slide Rule from the early 60's.Set it all up in your GarageNice WorkRNS