The young man shown here is probably getting ready to collect his first Social Security check, but fifty years ago, he undoubtedly took home the blue ribbon at the 1970 Science Fair. His project was shown in the August-September 1970 issue of Science and Electronics. According to the magazine, the project would show off knowledge and understanding, but would also require dexterity with tools.

The project was a moving-coil ammeter, not unlike a commercially made meter movement. While the magazine didn’t use the moniker, this type of meter is also commonly known as a d’Arsonval meter movement, after Jacques-Arsène d’Arsonval. For less advanced students, the article referred back to construction articles for some more primitive meters, such as the hot-wire ammeter we previously profiled. Most of the meter’s mechanical parts were made of wood, so the project required some expertise in the wood shop. The form for the moving coil was made with balsa wood, whose light weight ensured a sensitive movement.

The finished product could be accurately calibrated by using a commercial VOM, a battery, and a potentiometer. Current readings were noted on the commercial meter, and then marked on the face of the homemade meter.

According to the article, if the builder used reasonable care and followed instructions, they would be assured of a good grade and congratulations from friends and teachers.  And fifty years later, there’s no reason to think the result would be any different.