So a couple AND and OR gate chips are out of the question too I assume. Those were developed in the 1960’s so to me that’s old school.
YEP!!! The sixties were the beginning of 'new school' with the advent of space exploration and the electronic revolution. Before then, engineers used slide rules, calculators were banned in school and kids had to memorize the multiplication tables from 2-12.
I remember those days, and I’m from the 70’s and went to school in the 80’s. But I did love electronics so I tinkered then… and still do… lol.
Well, that explains it then. I was around for WWII, Korea and served proudly in 'Nam and all that was before you apparently were born. Anyway, I'm using what I have on hand which are a bunch of Atlas #200 snap relays that I got for the 'old school' price of $4.50 and for which the 'new school' price is $20.98. But thanks for your input. Maybe, if I need more crossings than I have snap relays, I'll read up on Arduinos and maybe consider using them.
I think you missed it by a decade. The 1970s saw the first portable scientific calculators (HP and TI). My brother, an engineering freshman at the University of Texas in 1976, was in the first class to require scientific calculators. Many upper classmen were still using slide rules and trig tables. "Computer" was originally a profession, someone who manually performed calculations, often with the aid of slide rules. They were still in heavy use during the Apollo program. I grew up in a suburb of Houston, and my best friend's father was an engineer at NASA. When my dad, a chemical engineer, was issued a TI scientific calculator by his employer, he commented that "it adds, subtracts, and gets the decimal point in the right place," things his slide rule could not do. He'd been issued an HP scientific calculator a year or so earlier, and had to turn it back in, because he could not adapt to the Reverse Polish Notation operation of the HP calculators. It's second nature to my brother and me, but the TI calculators fit our college budgets much better. I use a calculator app on my phone, in RPN mode, because it makes more sense to me, and is more keystroke-efficient. But before I used the app on my phone, I used AOS (TI style) scientific calculators because they were cheaper. My dad had used a circular slide rule, because it fit in his pocket (with the same precision as a foot-long slide rule that had to be worn on the belt in a scabbard.) Also, the calculations never "ran off the end," like on the more typical straight slide rule. This avoided the need to "reset" the slide rule by manually transferring an interim result to the other end, or perhaps re-ordering the operations to prevent that, in order to continue the calculation. I was in the first class of engineering programming (Fortran) in the spring of 1982 at University of Arkansas that did not have to use any punch cards.
You mentioned Fortran. It was invented in 1959. COBOL came on in 1960. I recall very vividly a boy in our high school had a calculator in class and was sent to the principal's office for discipline because of it. I graduated from high school in 1963. Teachers were still mimeographing tests even though the Xerox machine was invented in 1959. I went to college in Dayton, Oh which was the home of NCR, the National Cash Register Company. In 1966 NCR donated their biggest computer to UD's new School of Business. Maybe the electronic age started earlier here than out West? Anyway, I'm using the snap relays.
The first school district I was in when I started school (1980 to 1987) used Mimeograph machines to copy tests and other hand outs. They were purple and hard to read. When I asked (4th or 5th grade) why not use the copy machine, I was told it’s too complicated to use. I thought that was BS my mom taught me how to use the one at her office when I would visit to copy coloring pages out of one of her coworkers coloring books she kept for her own kids when they would visit. It wasn’t complicated… We moved before my 8th grade year started to a small town that’s not even a map dot and the school there was amazing. We had computers in every room, a well equipped computer lab (all Apple computers) a wood shop, and metal shop that even had a foundry. It was night and day difference. My kids now go to that first school district and while they embrace the digital age now, they never really got into teaching the things I had in my time at South Kitsap. The closest thing my kids had to a shop class was a jewelry making class… I had that, and auto shop, and metal shop, wood shop, photography, stage craft (carpentry class basically), electricity, robotics there was even sewing that was more about practical sewing like upholstery than it was dress making. I know the times play a part in what was and what is, but SK still offers many of those classes that I got to take.
Inkaneer and oldies, This conversation is fun! I had a slide rule for my education. But, for my 1976 BSc engineering final exams, I soldered together a Sinclair mailer calculator kit. The logarithms were accurate to only 2 places. The book of logarithms was more accurate. I am looking forward to your Snap-Relay design with an era appropriate hand drawn schematic. I had a Hornby UK relay to switch a signal. However, I went onto a short career as a Signal engineer for British Railways. We used electromagnetic relays for signaling logic. The relays all had a big spring to force the relay to the Off position if a connection broke or power failed. This was called Fail-Safe and resulted in a lot of red signals, good times! - Tonkphilip
Unlike the electromagnetic relays you worked with the Atlas snap relay does not have a return spring. It requires electrical energy to activate the solenoid to move in both directions. There are schematics available online which can depict this better than I can. Just Google 'Atlas #200 Snap relay'
Inkaneer, Yes, the Snap-Relay is a wonderful thing, as it has memory or logic that something has triggered the solenoid. The reed switch is good for the trigger pulse. Other older mechanical solutions include a sprung track or brass shoe but these older electro mechanical solutions work better in HO scale with the heavier cars. Looking forward to seeing your logic schematic for your matrix of snap switches with reed switches. - Tonkphilip
A common issue with persistent mechanical "memory" (that survives a power cycle) is initialization after a power cycle. The solution often adds more complexity and/or expense.
