A geek named Chris Gregg wanted to convert an old-school typewriter to a printer that could be controlled by his computer. To start the project he laid hands on a Smith Corona electric typewriter from the 60s to use for the project. His original goal was to use the computer to drive the key switches without actually having to touch the keys of the typewriter.
However, he soon realized that this particular typewriter model didn’t use keys that are electrical switches. What the keys did was activate a complicated mechanical system inside the typewriter that triggered a clutch to strike the page. After this realization, Gregg put the project aside.
He came back to the projector eventually with a new plan, rather than having the computer drive the keys, he would use solenoids to activate the keys with the solenoids controlled by his computer. The project moved forward with help from some students in Gregg’s classes and uses a TI TPIC6A595 shift register capable of handling up to 50 volts.
An Arduino Uno converts serial over USB to a bit stream that can be used by the shift registers. A custom CUPS driver allows the MacBook to print using the typewriter. The project worked out so well that the typewriter can even play “The Typewriter Symphony.” Check out the video of it in action below.