Shown here in the November 1960 issue of Electronics Illustrated is 17-year-old Belmont Frisbee, then a student at Burroughs High School in China Lake, California. He was one of the winners of the 1960 National Science Fair and is demonstrating his winning entry here. The device he constructed is dubbed “Adicof,” and allowed the entry of numbers into a computer by writing them by hand.

The digit is written with a metal stylus onto a panel with inlaid copper strips, as shown in the diagram below. For example, when making a “2”, the stylus will pass over strips 1, 2, 3, 4, 5, and 7.

The nearly forgotten art of relay logic is used to determine which number was being written. A partial diagram is shown below. Each strip is attached to the coil of a relay. The first relay is single pole, double throw (SPDT). The next one is DPDT. The one after that is 4PDT. Unfortunately, there probably weren’t any 128PDT relays on the shelf for the seventh relay, so multiple relays were used for the higher stages.

I believe the circuit shown here is simplified in one respect: For this to work, it would be necessary to use some type of latching relay, since the stylus would no longer be in contact with the pad when the next pad is contacted.

The simplified diagram shown here uses light to indicate the digit drawn, but for his exhibit, Mr. Frisbee hooked the output to a computer.

Today, it’s a trivial matter for a computer to recognize hand input, but the concept is nothing new. Sixty years ago, a high school student accomplished the task with electromechanical relays.

Mr. Frisbee continued as an engineer after high school. He was issued at least two patents (4,477,812 and 8,009,084), both of which involve radar, and both of which list the U.S. Navy as the assignee.

The magazine highlighted some other winners of the 1960 National Science Fair. Remarkably, it includes an electron microscope constructed by Marvin Hutt, a New York high school student, despite having experts tell him that making one at home was impossible. For students looking for inspiration for a science fair project, perhaps there are a few who could build an electron microscope from scratch. But in an age when computing power is taken for granted, there’s something to be said for being able to use mechanical relays for programmable logic. The science teacher might not even realize that it’s possible, and proving the impossible is always a good way to take home the blue ribbon.