Change internal logic from relays to an Arduino Redo

An electronic project at a local science center was showing its age, calling for a refresh: in this case, rebuilding it almost from scratch with an Arduino instead of relays

- Scott Sumner

A museum exhibit called Buzzwire looks like outlines of two oversized hands giving you a high five (Figure 1). Each hand has a metal handle with a loop, and your goal is to move the loops up and down the hand without touching it. For an even bigger challenge, you can try to do both hands at once in the same or opposite directions. If either loop touches the hands, a buzzer and light come on and the handle vibrates.

The original circuitry for the hands comprised interconnecting timer relays to switch the assorted components. The design had no microcontrollers or anything smarter than a switch, which had several drawbacks – but the main one was that if the puzzle was abandoned mid-run, the light, buzzer, and vibration motor would run continuously until the handles were removed.

Physical Rebuild

While I rebuilt the control electronics, I sent the case out to be rebuilt as well. The original design was made out of plywood and had started to accumulate a lot of dings and scratches. The case rebuild was very helpful because it showed areas that needed to be reinforced. Ultimately, I had the entire front panel replaced with Delrin, a very hard plastic that will withstand wear and tear better than plywood. It also brings a fresh look for anyone that has seen it before.

The physical rebuild also incorporated larger vibration motors in the handles. The old version used pager motors, which were more heard than felt. The machine shop I worked with fabricated new handles from scratch that incorporated larger motors, making the buzz much more noticeable.