deskthority

Thanks to [DMA] I actually know a bit about this keyboard (he'll be able to enlighten further if he peruses).

It's a terminal keyboard used on the Express 2 line in Russia (or Soviet Union when it was actually built).
The keyboard itself is really odd, because Rafi is a German Company (and I don't believe it was in East Germany either...).

AND, this is where I start producing force curves for every keyboard I post!

Included a couple pictures from testing. Still trying to figure out the best test fixture when the switches I'm testing are all different sizes (and may not be removable...).
I tried to put Press/Release points on the graph, but I wasn't able to get the hall effect sensors working (I suspect they need a pull-up resistor).

Haven't been able to find any info on these switches yet. Only two types in this keyboard. But from the slider, it seems there was a locking version as well.

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Would be neat if I could embed the interactive plotly graphs directly into this post...oh well. If you click on the greyed out legends (on plot.ly) you can overlay the other test data.

Flickr Album

Impressive work, good to see you finally got around to producing force curves. Yes RAFI is a quite old (west) German company, I guess the Russians decided to get some quality switches from Germany then.

I finished the force curve gauge back in March/April. However, it took me quite a while to get all the post-processing math working well enough.

For those that are interested, all the messy code is here -> https://github.com/kiibohd/force
Building one is sorta expensive, in the thousands for just materials...let alone all the modifications. On the plus side, it's *really* sturdy, and since it isn't a stepper motor you don't get vibrations from the motor affecting the load cell sensor.

Currently everything is wired up with a Teensy 3.2. Atm, I'm getting so much data from the ADC that I average out quite a bit of it (it's good enough to see friction, and other fun stuff like on Cherry MX Blue switches where the slider bounces around).

Wow. That board is FUCKING GORGEOUS. Great work on the force curves too, I hope we can see some nice results from that .

Express-2 (Экспресс-2) is a Soviet Union railroad booking system (Think Sabre, but for railroads). It was a regional system, but they were interconnected.
It was in service 1982 to 2005 and run on S/370.
Safe to say thousands were produced. Every railway station in 90s had at least one (at least that's what I remember).
There were 90, 92 and 94-key versions according to site
Damn hard to find any photos of the terminal or any parts of it - there were no digital cameras those days, and no one cares about PoS terminals.

Those terminals were made by Hungarian company, Vilati. That would explain the mix of Soviet and Western parts - Hungary was sort of half-communist half-capitalist country, owing to it's unique location on Eastern Bloc's border.