“An encoder converts information from one format or code to another. The device presented in this Instructable will convert the decimal numbers 0 through 9 into their binary equivalents. However, the concepts presented here can be used to create encoders for any reasonable number of items and codes (say 20 or less). Aside from a few easily obtained microswitches and screws, all of the parts for this mostly mechanical machine can be 3D printed.
Why Am I Doing This?
I recently came across a book published in 1968 entitled “How to Build a Working Digital Computer” by Edward Alcosser, James P. Phillips, and Allen M. Wolk. Believers in the “learn by doing” philosophy, they show how to construct such a computer using “simple inexpensive components usually found around the house or in a neighborhood electrical parts store”. This is often called the “paperclip computer” book since they use paperclips to create various switches throughout the design.
So I’m going to make a “Working Digital Computer” based on the book that I am calling the WDC-1. The book is divided into sections based on the main components of the computer like Arithmetic Logic Unit, Core Memory, Control Unit, and you guessed it Decimal to Binary Encoder which I am going to tackle first.
Above is a diagram from the book showing the encoder construction. They used an empty thread spool, wrapped it with uninsulated wire, then covered the wire with paper that had cutouts for the binary codes. Four paperclips were used as contacts to read the codes (I told you there would be paperclips). It was an ingenious design using only the promised household items.
Upgrading the Design
While my design does not use paperclips, I believe it embodies both the concept and spirit of the original. I’m not going for a “pure” replica here. At the end of the day someone should be able to “run” programs from the book on the new machine. Starting with the Decimal to Binary Encoder.
In addition to the printed parts you will need the following (seen above):
4 Cylewet Momentary Hinge Metal Roller Lever Micro Switches - Amazon
4 M3 x 3 mm bolts”