21lb 1969 Optical Sensing Magnetic Tactile Keyboard from Viatron System 21

fricked

15 Aug 2021, 03:00

Hi I got this keyboard

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This is still a work in progress; I have finally cleaned it and am now working on converting it to USB. Will probably be a while though as I have a lot of projects

Lots of photos in here:
Spoiler:

Unfortunately it was not packed appropriately for a 21lb keyboard and got pretty hurt in shipping

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Big connector

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Caps removed

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Under the caps was some material that has completely degraded. When it got tossed around in shipping it got outside of the assembly and all over the case. This stuff is worse than any model f foam I've dealt with. So insanely sticky and hard to get off. I filled a 2L jar with 99% isopronanol and soaked everything I could fit in it for days but even then it needed tons of elbow grease. And obviously most of the parts did not fit

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Underside of the assembly. Middle part is one massive block of steel

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Yes, that's a 120V transformer. For some reason they decided to run 120v ac through the same cable as everything else. The output powers the bulbs which illuminate the channels for the light sensing.

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13 bulbs for 13 channels

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The receiver circuit (oddly channel 13 (strobe) is not connected)

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Lens for focusing the light onto the little photocells

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My disgusting schematic (circles are the photocells)

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Cranks removed. You can see the light channels carved into the metal block

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All the cranks laid out in order. Each of the regular keys has a shutter in 4 out of 8 of the main light channels for 4-of-8 encoding. Each of the regular keys also has a shutter in channel 13 presumably for detecting that a key is pressed; however this channel was not connected on mine. The role of the shutters is to block light for that channel while the key is pressed. For example, if you pressed a key with shutters on first, second, fifth, and eighth channels then those channels would not receive light on the other end. You can think of it as the byte 11001001. This benefit of this 4-of-8 design is that you can detect clashes; any byte with more than 4 bits set would imply that more than one key is pressed.

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There are also 6 modifier keys intended to be pressed in conjunction with other keys so they have 4 separate channels.

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All cleaned up. Each crank hinges on a bar at the top like in a typewriter and the blue leaf springs provide the return force.

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Midway through the travel, the crank comes into contact with a second set of leaf springs on the underside. These are held down (up?) by a big magnet running along the length of the keyboard. It takes a certain amount of force to get the leaf spring to separate from the magnet and once it does the attraction rapidly drops off, ensuring that that part of the travel distance is traveled fast. This part of the travel distance coincides with the actuation which is somewhat gradual. If not for this tactility then you would be able to hold the key in a position where the output is floating.

video: https://i.imgur.com/4cobkcq.mp4


I would love to see a force curve for this keyboard, I imagine it would look something like this:

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Regarding restoration I glued the keycaps where necessary with jb weld and am considering polishing them. Here is the worst one:

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Conversion
I like to keep things original but I am probably not experienced enough in electronics to be feeding mains into an all-metal keyboard. Plus 3 of the bulbs were burnt out so I will replace the transformer and bulbs with leds. I was only able to find one visible led strong enough with a low enough beam angle to operate the sensors and they cost an entire dollar each :lol: . Because the output of the receiver is so slow i will use schmitt triggers. If I hadnt found those leds I would have used infrared ones and maybe supply my own receivers but thats less fun

Key Feel
With all the stickiness cleaned out I could finally type on it and honestly it kinda sucks. When you press a key light/slow you really feel the tactility but if you press it fast/hard you don't feel it at all. The effect when I type on it is that it feels very inconsistent. Also, because the keys hinge from the top, the ones that are closer to the top feel a lot heavier and have shorter travel distance. The bottom row is about 3x as far from the hinge as the top row so you can imagine the inconsistency.. The upside is smoothness; this is the smoothest key travel I have ever felt. I can't even compare it to other boards, there is just 0 perceptible scratchiness.
Last edited by fricked on 15 Aug 2021, 18:04, edited 2 times in total.

John Doe

15 Aug 2021, 03:11

Bloody MECHANICAL keyboard.

User avatar
jsheradin

15 Aug 2021, 17:14

Awesome to see another one of these! I just ran through mine a couple weeks ago:
jsheradin wrote:
30 Jul 2021, 03:00
Viatron:
Spoiler:
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The manuals are a little vague but I believe the logic is intended to run at -14V although it should function fine on a lower positive voltage. The indicator light also seems to run at 14Vdc just fine. The optical bulbs run at about 2V RMS but pretty high current hence the internal mains transformer.

The optical sensors are pretty much what were used in punch card readers but I can't find a datasheet for the photo-transistors themselves.

From what I can tell the board is 1KRO not including mods so I haven't been in a rush to get QMK working with it. I'm trying to find what connector this cable uses to make a clean converter box.

This system was evaluated by the CIA for data processing use and there's a bunch of declassified reports about their try-out units. Someone complained about the keyboard way back then:
Spoiler:
Screenshot_20210723-180721.jpg
Screenshot_20210723-180721.jpg (55.4 KiB) Viewed 665 times

fricked

15 Aug 2021, 18:03

jsheradin wrote:
15 Aug 2021, 17:14
Awesome to see another one of these! I just ran through mine a couple weeks ago:
jsheradin wrote:
30 Jul 2021, 03:00
Viatron:
Spoiler:
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The manuals are a little vague but I believe the logic is intended to run at -14V although it should function fine on a lower positive voltage. The indicator light also seems to run at 14Vdc just fine. The optical bulbs run at about 2V RMS but pretty high current hence the internal mains transformer.

The optical sensors are pretty much what were used in punch card readers but I can't find a datasheet for the photo-transistors themselves.

From what I can tell the board is 1KRO not including mods so I haven't been in a rush to get QMK working with it. I'm trying to find what connector this cable uses to make a clean converter box.

This system was evaluated by the CIA for data processing use and there's a bunch of declassified reports about their try-out units. Someone complained about the keyboard way back then:
Spoiler:
Screenshot_20210723-180721.jpg
Nice! Thanks for sharing, cool to see the differences like in the keycaps. Your contamination shield is in much better shape too haha, is that yellow part a sheet of metal? A lot of your internal parts are black, did you paint/plate them?

I sorta had a feeling the logic would run at >5v but wasnt sure, I tested with 5v and it looks to be working fine. Makes life easier for converting but indeed it is not very usable.

I had found a female connector for it: https://www.capitolareatechnology.com/c ... 6-pin.html
but this part on its own seems a bit useless..

User avatar
jsheradin

15 Aug 2021, 18:23

fricked wrote:
15 Aug 2021, 18:03
Nice! Thanks for sharing, cool to see the differences like in the keycaps. Your contamination shield is in much better shape too haha, is that yellow part a sheet of metal? A lot of your internal parts are black, did you paint/plate them?

I sorta had a feeling the logic would run at >5v but wasnt sure, I tested with 5v and it looks to be working fine. Makes life easier for converting but indeed it is not very usable.

I had found a female connector for it: https://www.capitolareatechnology.com/c ... 6-pin.html
but this part on its own seems a bit useless..
These were very low production numbers from what I can tell. The keyboard alone was over $2kUSD adjusted for inflation. Cool to see that there were so many little variations made despite only being made a couple years. The company went out of business pretty much immediately but there were some retailers that sold new old stock stuff for a while. There's one retailer that advertised a 'fungus special' since their units apparently grew hair from sitting so long. https://worldradiohistory.com/hd2/IDX-S ... e-0125.pdf

The yellow part of the shield seems to be waxed paper; the foam completely turned to dust so I just brushed it off. The main block of mine is black anodized aluminum. It looks like it was extruded with most of the features and then a bit of final machining took place. Total overkill but I guess this sense system depends on there being basically zero flex.

Thanks for the pointer on the connector! Usually these type of connectors are sold in pieces where you buy the pin holder, pins, shell, retainer, etc all separately. Hopefully that model number is enough to track the rest down.

User avatar
jsheradin

18 Aug 2021, 19:38

fricked wrote:
15 Aug 2021, 18:03
I had found a female connector for it: https://www.capitolareatechnology.com/c ... 6-pin.html
but this part on its own seems a bit useless..
The connector is definitely part of TE Connectivity's MR series or was at least replaced by it. I picked up one of these https://www.digikey.com/en/products/det ... 6-0/187728 along with the matching socket pins. It almost fits except that the key slots are in different positions. It will fit just fine with some minor trimming; the pins themselves mate perfectly.

I'm only finding MR II series though, presumably there was an MR I that may fit without modifications. Viatron could have also ordered custom key locations for whatever reason.

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