Very, VERY nice work!
-Dave
On 03/24/2013 06:38 AM, Lawrence Wilkinson wrote:
I've been working on an IBM Selectric typewriter
which I bought earlier in
the year. It is the I/O Selectric type 735 which differs from a normal
Selectric in having the solenoids and switches on it to allow it to be used
as a printer and keyboard.
When I got it the motor wouldn't run, and the mechanism was jammed. The motor
problem was its thermal trip, which is meant to be the resettable type, so I
replaced that. I gave the whole thing a clean with degreaser, which freed up
the mechanicals, then oiled and greased it. It then worked happily as a
typewriter.
I have made a small interface, based on an Arduino Mega 2560, which provides
a serial port. Currently this only supports printing, but will be extended
to include the keyboard. It uses almost all the digital I/O on the Mega (15
solenoids, 27 contacts.)
There are still some adjustments to be done, and I am awaiting a set of
Bristol Wrenches (Keys) so I can safely do these. I have tried using Torx
and Allen keys, and while they can be made to 'fit', it doesn't seem like a
good idea.
There are some pictures and videos of the typewriter here:
http://www.flickr.com/photos/ljw/sets/72157632841492802/
You can get the Arduino interface code here:
https://github.com/ibm2030/IOSelectric
I haven't yet documented the hardware I used for the solenoid drivers, but if
anyone is interested I can put some notes together (basically: Arduino output
to 2N7000 FET buffer to ITS4140N +48V high-side driver on the output side,
and a simple 250R pullup to +5V on the input side.)
Manuals here:
http://bitsavers.informatik.uni-stuttgart.de/pdf/ibm/typewriter/selectric/
(or other Bitsavers mirrors)
Info on the Mega2560 here:
http://arduino.cc/en/Main/arduinoBoardMega2560