Keyboard Electronics 101: Teensies and Related for Novices

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Hypersphere

16 Apr 2014, 18:47

My keyboard odyssey has led me back in history (at least in the IBM lineage) from the Model M to the XT, and now I am hoping I might eventually be able to acquire a Kishsaver and/or beam spring keyboard. Inevitably, such a journey will require doing some modifications to the electronics of the keyboard, such as replacing the controller and/or installing a Teensie (along with its firmware and then reprogramming the keyboard).

Of course, I have read the threads about the amazing Soarer Converter and related matters, and I am in awe of Soarer and others who obviously have a deep understanding of keyboard electronics and programming along with the mechanical knowhow to undertake the necessary soldering and wiring.

All of this can be rather daunting for those who are contemplating for the first time such tasks as getting an XT or IBM terminal keyboard up and running with a contemporary computer.

I know what the experts are thinking: "It's not rocket science! You just have to connect 4 wires!" Nevertheless, it would be great if the experts could recommend to the novices a systematic process, e.g., the best posts to read, for acquiring the basics of keyboard electronics as they pertain to installing Teensies. It would be helpful to have clear descriptions (preferably with pictures) of basic soldering skills; which wires to connect from A to B; when a Teensie can be installed with the keyboard controller intact vs. when the controller should be replaced; pros and cons of using Teensie version 2.0, 2++ 2.0, 3.0, or 3.1; basic anatomical features such as headers, controllers, and PCBs; and various ways of installing a case-mounted connector (or an external switch box) after installing a Teensie.

Of course, ultimately one simply has to do it and learn from mistakes, but it could help to have a good guide to follow.

Thanks. I look forward to your helpful suggestions.

User avatar
Muirium
µ

16 Apr 2014, 19:24

Good idea. I'll take some pictures of the insides of my "Universal Soarer" box and write up an explanation of how it works.

So far, I haven't mounted a Teensy inside a keyboard, other than the 60% I built for myself. That one had a few more than 4 connections. 5 rows + 15 columns = 20 instead.

User avatar
Hypersphere

16 Apr 2014, 20:08

Hi Mu. Thanks for responding. I was thinking that it could be good to have two sorts of keyboard electronics guides or wikis. One might be focused on matters relating to Teensies; the other might be geared toward building one's own keyboard.

User avatar
Muirium
µ

16 Apr 2014, 20:12

They are indeed quite different jobs. Although Teensies forever wind up at the heart of both of them! Rare is the keyboard I use without one of those. Even my Apple Extended II is now converted from ADB to USB via Teensy. Saves me the bother of finding one of the old adapters.

User avatar
Hypersphere

16 Apr 2014, 21:06

So, you use the Teensy extensively but you have installed it into only one of your boards? I presume this means that you use an external converter box and/or the switch box that I saw on one of your posts? It would be good if the tutorials or wikis would include "how to" information for both external and internal Teensies, perhaps with both circuit diagrams and photos showing the nicely color-coded wires.

User avatar
Muirium
µ

16 Apr 2014, 21:25

rjrich wrote:So, you use the Teensy extensively but you have installed it into only one of your boards? I presume this means that you use an external converter box and/or the switch box that I saw on one of your posts?

Right. That one box handles all my IBMs besides the Kishsaver. The sockets (DIN, Mini-DIN and RJ45) are cheap and freely available over here, but Teensies are quite a bit more expensive (local online retailers don't cost much different from shipping straight from PJRC at international rates). So I made it to save on cash as well as convenience. Since then I've stocked up on Teensies and still don't intend to build them into boards as I've found the box quite excellent. Perhaps if I were building Bluetooth into a board, though…
rjrich wrote:It would be good if the tutorials or wikis would include "how to" information for both external and internal Teensies, perhaps with both circuit diagrams and photos showing the nicely color-coded wires.
Well, here's the thing: wire colours are arbitrary and potentially dangerous to rely on. What really matters is the pinouts. You'll find diagrams aplenty in the documentation inside Soarer's Converter's zip file. A proper step-by-step guide is something worth making, but there's still discretion required. Caveat hacker!

As for circuit diagrams, what does a 4 pole 3 position rotary switch look like? (Besides a mess!) Because that's the octopus at the heart of my Soarer box.

User avatar
Hypersphere

16 Apr 2014, 22:12

Muirium wrote:
rjrich wrote:So, you use the Teensy extensively but you have installed it into only one of your boards? I presume this means that you use an external converter box and/or the switch box that I saw on one of your posts?

Right. That one box handles all my IBMs besides the Kishsaver. The sockets (DIN, Mini-DIN and RJ45) are cheap and freely available over here, but Teensies are quite a bit more expensive (local online retailers don't cost much different from shipping straight from PJRC at international rates). So I made it to save on cash as well as convenience. Since then I've stocked up on Teensies and still don't intend to build them into boards as I've found the box quite excellent. Perhaps if I were building Bluetooth into a board, though…
rjrich wrote:It would be good if the tutorials or wikis would include "how to" information for both external and internal Teensies, perhaps with both circuit diagrams and photos showing the nicely color-coded wires.
Well, here's the thing: wire colours are arbitrary and potentially dangerous to rely on. What really matters is the pinouts. You'll find diagrams aplenty in the documentation inside Soarer's Converter's zip file. A proper step-by-step guide is something worth making, but there's still discretion required. Caveat hacker!

As for circuit diagrams, what does a 4 pole 3 position rotary switch look like? (Besides a mess!) Because that's the octopus at the heart of my Soarer box.
Surely no worse than the circuit diagram of the "Interocitor" from the film, "This Island Earth".

Here are the parts, as obtained from the Electronics Service:
Parts.jpg
Parts.jpg (11.42 KiB) Viewed 1609 times
And here is where to start, on the circuit diagram:
Circuit.jpg
Circuit.jpg (7.71 KiB) Viewed 1609 times
And here is Mu, telling me, "Well done, rjrich!"
WellDone.jpg
WellDone.jpg (61.71 KiB) Viewed 1609 times

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