IBM Selectric used as a PC keyboard.. anyone?

[Tove]

Hello forum
I've red on wikipedia about computer hobbyists on the 1970's turning IBM Selectric typewritters into computer keyboards. But of course, it was almost like making a keyboard from scratch as they had to put microswitches inside for each key.. it still seems like a really cool idea even though it sounds like a very complicated and difficult project. Still I did see a red Selectric for sale somewhere near me and I would be quite interested in getting an input from one to a PC. However I have no idea where one would even put the microswitch, to start with. I do have one typewritter at home but it's a bulky Yugoslavian 50's thing that's somewhat unpleasant to type on.
What I want to know is if anyone here has already attempted to do this, and how they did it. Did they simply take the switches and other guts out from an older mechanical keyboard? Or did they make a new interface that controls theese keys by themselves?
In any case it's just an idea and I want to know if it can be done. I'd also feel bad for destroying a Selectric if I made a mistake in the process that's why I'm not even going to attempt anything like this before I know if there's people out there who can give me some hints.
Cheers

[vivalarevolución]

Don't worry, there are plenty of Selectrics out there that people are selling for parts or repair that you probably could play around with.

I know some people around here have gotten a Wheelwriter keyboard to work with a computer.  The USB typewriter mod is well known.  I am sure that some people on here could put their heads together and get a Selectric working with a computer.

One big problem is the high cost of working Selectrics.  You have to pay at least over $100 to get one in at least reliable, working condition.  That sort of investment is discouraging for a tinkerer.

[dorkvader]

so I've been wanting to do this for a while: there are a few ways.

First is to do the IBM method. IBM used selectrics as computer input terminals back in the 1960's before beam springs were a thing. I finally got a chance to take apart an IBM mag card typewriter at keycon and see how it worked.

Under the typebars, there are 6-8 horizontal bars. These get displaced every time you type. If you pay attention, each keypress displaces a unique number of these. IBM put a magnet under each and a reed switch to detect the keypress. You can just as easily use a microswitch under each and "decode" the presses. This is likely the best/easiest way. It's also 100% reversible and won't affect the mechanism much.

Thanks IBM for including digital encoding of all keystrokes: really thinking ahead there.

Other options include:
microswitch under each typebar. I rejected this because it would change the feel
optical switch between each typebar. Expensive, requires some shielding so they don't interfere with eachother, couldn't find ones thin enough to prevent having to stagger them.
magnets on typebars and hall sensors. This is what I was going to go with but I like the IBM method above.

Now there are differences between the mag card and the 15" selectric it's based on. If you look at the frame, you'll notice there there's drilled points with nothing attached. The mag card is pretty well full up with stuff. Some components are rerouted, and the printing is disabled. I didn't have enough time to fully understand it and figure out how to re-enable the printing, but at least one spring/plastic assembly had snapped which prevented it from advancing the typeball. I don't know how to disable the printing of a selectric (but I don't really want to: I like the loud thump of the typeball hitting the platter.)

Ok hope this helps. I can take mine apart with picture if you like.

Another mod would be to convert it to dvorak, but it's a lot more complex. IBM did make dvorak selectrics (barbara blackburn had one) but I only know of one.

One big problem is the high cost of working Selectrics.  You have to pay at least over $100 to get one in at least reliable, working condition.  That sort of investment is discouraging for a tinkerer.

I got two working ones for $12.75 with tax. One included the dustcover. I got mine at auction, but you can check craigslist for deals as well.

[CPTBadAss]

Stupid Dorkvader....STOP POINTING OUT COOL THINGS TO ME! First that Texas Instruments Silent 700, now you tell me I can get a Selectric working on my computer?! My wallet doesn't like you

[engicoder]

How about sensing the activation of the tilt and rotate solenoids, and then converting that into the appropriate key code?

[engicoder]

I used to have a really old paper on driving a selectric using a microcontroller to activate the solenoids, but there are all kinds of crazy jam conditions that make it less than trivial. I'll see if I can find it.

Update: Here it is:  selectric-typewriter-controller.pdf

[dorkvader]

How about sensing the activation of the tilt and rotate solenoids, and then converting that into the appropriate key code?

There are no solenoids in a normal selectric.

You could sense how far the rope travells to tilt / rotate the typeball, but I don't have much faith in that method.

The selectric input terminals and mag card have solenoids in them to allow it to be used as a printer, but those are already set up to be attached to a computer anyway.

[engicoder]

Shows my ignorance on the topic of how Selectrics work. Embarrassing considering I own 3 ;-) I read that paper a while back and got the impression that's how they all worked. What about this thing? https://www.youtube.com/watch?v=H8P1JrivTsE

[E TwentyNine]

You could sense how far the rope travells to tilt / rotate the typeball, but I don't have much faith in that method.

No?   Would think it would be straightforward with a couple of linear potentiometers with return springs.

Something along these lines scaled down:  https://www.manylabs.org/project/forceSensor/

(Not that I'm about to try it....)

[dorkvader]

You could sense how far the rope travells to tilt / rotate the typeball, but I don't have much faith in that method.

No?   Would think it would be straightforward with a couple of linear potentiometers with return springs.

Something along these lines scaled down:  https://www.manylabs.org/project/forceSensor/

(Not that I'm about to try it....)

The memory typewriter is like a mag card in that it's implemented as an input terminal and a printer, so there are magnets, reed switches and solenoids able to drive the thing fully remotely.

They are much more rare than a normal selectric. If you have one, converting it to USB (and as a printer!!) is almost trivial. (just wire reed switches to a teensy directly (through a matrix with diodes if necessary) and wire the solenoids to a power supply (tap the AC input with a small power supply board) with a teensy controlling through transistors).

One guy put a bank of solenoids over the keys in a very old school way to make a selectric printer.

You could sense how far the rope travells to tilt / rotate the typeball, but I don't have much faith in that method.

No?   Would think it would be straightforward with a couple of linear potentiometers with return springs.

Something along these lines scaled down:  https://www.manylabs.org/project/forceSensor/

(Not that I'm about to try it....)

There are a number of ways to do that. I was thinking of a row of hall efect sensors and dangle a magnet from the string. I think the big issue here is clamping something to the string properly. That's why "other" ideas seemed to be better to me.

[E TwentyNine]

No?   Would think it would be straightforward with a couple of linear potentiometers with return springs.

Something along these lines scaled down:  https://www.manylabs.org/project/forceSensor/

(Not that I'm about to try it....)

There are a number of ways to do that. I was thinking of a row of hall efect sensors and dangle a magnet from the string. I think the big issue here is clamping something to the string properly. That's why "other" ideas seemed to be better to me.

I was thinking they could be disconnected from the ball tilt/turn points and connected direct to pots.   Ball would be constantly typing on one character though.

If leaving everything intact, I wonder if a optical encoder would work.

[berserkfan]

Stupid Dorkvader....STOP POINTING OUT COOL THINGS TO ME! First that Texas Instruments Silent 700, now you tell me I can get a Selectric working on my computer?! My wallet doesn't like you

get the Dorkmaster to build you some custom keyboards and your wallet will really really loathe him.