3M Whisper Writer keyboard

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OldIsNew

18 Nov 2017, 16:58

I came across this for a few dollars so I thought I'd check it out. It''s from a 3M Whisper Writer 1000 teleprinter. Unfortunately it's missing the 3M badge on the front.
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It's a Hi-Tek switch board. the case is rather flimsy feeling plastic, but I guess it was a carry with you modem based terminal after all.
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Switches:
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I went ahead and Teensyfied it - the switches feel OK, but not my favorite.
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It's certainly a very basic keyboard (but it is only 11 1/2 x 6 in). I mainly like it for one rather philosophical button on the board:
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Now I just need to find one with a "Why Are We Here" button.

green-squid

18 Nov 2017, 17:07

Good job!

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seebart
Offtopicthority Instigator

18 Nov 2017, 17:10

This keyboard will please the 60% crowd. :lol: These switches are pretty quiet but louder than a whisper...I guess back in the day this may have been an argument. Love the "who are you" keycap.

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Sangdrax

18 Nov 2017, 20:57

Glad to see one of these opened up. That expensive complete terminal on ebay the last number of months made me wonder what was inside.

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Daniel Beardsmore

09 Dec 2017, 16:06

Interesting — the alternate action sliders (the two at the top left) don't have the thicker corners. That suggests that the corners are no greater in exterior dimensions, but rather that the other sliders are thinner along the top, bottom and sides. However, the thickness of the slider walls seems to be the same. It's very hard to tell from that photo.

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OldIsNew

11 Dec 2017, 04:23

Daniel Beardsmore wrote:
Interesting — the alternate action sliders (the two at the top left) don't have the thicker corners. That suggests that the corners are no greater in exterior dimensions, but rather that the other sliders are thinner along the top, bottom and sides. However, the thickness of the slider walls seems to be the same. It's very hard to tell from that photo.

It's had to tell for certain even looking directly at the board but I think the slider thickness is the same for both - however slider walls between the corners on the regular keys are notched while the corner and the rest of the slider wall are equal height on the alt action keys. The beveling of the edges affects the apparent thickness in some pics as well.

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Daniel Beardsmore

11 Dec 2017, 22:35

I decided for my diagram to make the sides thinner instead of making the corners thicker, under the assumption that the shaft was the same size (I had to pick something). However, it's too hard to tell without callipers. The thicker corners don't seem to stop them from splitting either. It's a strange design, as I don't know any other type of switch where the sliders split apart.

It seems that the black sliders don't have these funny corners either. Those also have the weird island on the separator bar that nobody has managed to explain.

Understanding these will take some time yet!

Engicoder

11 Dec 2017, 23:19

I have one of these and some decent calipers, I can take a few measurements for you.

It does appear that the walls are thinner. The exterior dimensions of the slider are ~6.95mm in each direction while the "thinner" region is ~6.85mm across. The interior dimensions of both are ~5.35mm. The height of the slider above the housing differs between the two as well. The standard action extends ~2.4mm above the housing. The alternate action extends ~4.05 when released and ~0.95 when depressed.

The locking, or alternate action switches in this keyboard are in a block of two which is stamped T52-8250. The 8250 appears to be a date code as a block of 4 standard action switches is marked 8248 13 and most of the IC's on the main PCB have date codes of 82XX.
Last edited by Engicoder on 11 Dec 2017, 23:45, edited 1 time in total.

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Daniel Beardsmore

11 Dec 2017, 23:35

The diagram is done and it looks good enough now. If you want to document some of these strange characteristics, you are nonetheless welcome.

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