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Typo...matic (Part 1)

Started working on a Selectric II typewriter project. I used this typewriter last year to make business cards for the KC Maker Faire. This year I'm going to hook a bunch of solenoids up to it and throw in a micro-controller to allow me to control it's output with a PC via serial...

So far I've just got the mechanisms for key presses figured out and the solenoids mounted. Next I've got to get the control circuit board worked out and assembled, along with switches to read the keys when they're pressed. Then it's programming the micro-controller and figuring out what to do with the end result...Zork's been done...maybe epic ASCII art on tractor-feed any case it'll be KC Maker Faire and it'll be awesome.

I did get one solenoid hooked up in a bread-boarded circuit to make sure I had parts that would work...


  1. Teletype - roll paper - very long mazes...

    I must have wasted miles of paper this way. }:¬)

  2. nice, if this thing survives the maker faire i might create a program for mazes...or hook it up to a twitter feed and rename it "annoy-a-tron" :)

  3. If that is the machine I remember, you only need about 7 solenoids to choose any of the letters on the typing ball. Maybe another for the CR.

    There is a mechanism when you press any keyboard key which selects a series of rotation and tilt on the ball. Like tilt 1, tilt 2. For the top row, you don't tilt any. For Row 1 you trip tilt 1, for row 3 you trip 1 and 2 etc. (basically in binary) For the rotate I think there is rotate 1, 2, 4, ?-2? and a ?flip? that gets to the back side of the ball. Some of those rotate details I've forgotten. The trip levers for each of those bits were somewhere on the underside along the mechanism underneath the carriage bit toward the left/centre. The bits combine on a balance beam which converts the bits to a rotation distance which spins the ball the measured amount for that character. The mechanism is truly amazing; complex, yet elegant in it's underlying simplicity. I had a Selectric once (1980s) with all the solenoids already installed for use with a computer, but I never got a round tuit . (If I recall correctly there were a total of 12 or 13 solenoids, 7 or 8 for the ball, 1 carriage return, 1 tab, and I don't recall the rest.)

    Bottom line - you likely can get away with a lot less than one solenoid per key if you want to.

    David Meed (to email me use

    1. If you get a chance read the rest of my blogs entries...what you described is exactly what I've done. 6 to make the code, 1 to strike the key...6 more for special characters/actions.

  4. How come you used only 15 solenoids? Or am I mistaken. Dont you need one for each character?

  5. Sorry I should have been more clear. I was talking about an older regular typewriter not the selectric

  6. WOW! You turned a typewriter into a Daisy wheel printer which were sold back in the 80's and 90's. This is a cool project but it's nothing more than a Rube Goldberg machine. Its fascinating to watch. But if you wanted to create ASCII art or just type a letter the TRS-80 Daisy Wheel II printer would have given you which could type 500 words per minute allowing a whole edge to edge top to bottom 8.5x11 sheet of paper to be printed in about 6 minutes counting there will be an average of 3000 characters per page using a 12 Pitch Character wheel and using Non-proportional spacing. But I Have to admit taking a standard typewriter and robotizing it make for an interesting project Good Job.

    This will take yo back in time: