Here’s a unique project which repurposes old manual typewriters as keyboards for computers or Ipads, using an Arduino as the intermediary. It’s the brainchild of Jack Zylkin, a Philadelphia-based electrical engineer who has designed a kit that makes the conversion reasonably easy for anyone who enjoys hands-on projects. Jack explains:
Here’s how the computer attached to the typewriter knows which key has been pressed: When a letter is typed, the key’s metal support bar touches a single contact on the board. Meanwhile, the microcontroller is stepping a single logic “1” down the row of shift register pins and thus the leaf-spring contacts wired to them, letting the microcontroller detect the circuit made between the typewriter and the board. Then, like any other USB keyboard controller, it sends the appropriate code back to the PC. A few strategically placed magnets and reed switches detect the shift key, carriage returns, and whatever the user wants to configure as Alt or Ctrl.
Design files, including schematic and Arduino source code are available. The design is distributed under the Creative Commons Attribution-Share Alike Non-Commercial License.