(If you haven’t noticed by now, I use black unmarked project boxes to house my projects in. A lot.)
Every year the U.S. Department of Energy sponsors a regional science bowl in Puerto Rico. Nearly every private school on the island participates, with some teams showing more promise than others. What doesn’t change, though, is the fact that Notre Dame’s established science bowl team always seems to win first place year after year. When the date for the regional Science Bowl comes close every year, our coach usually just calls the four most promising science enthusiasts from grades 10-12 to take part the weekend before the actual event. Since none of us have time to practice, many points end up being lost because of buzzer misfires.
Here’s the lowdown: Two teams compete at once, with four players per team. Each player has a black “buzzer” box with a button and a green light, and the reader has a master box with a main light and reset button. When each question is finished being read, the first player to hit the button gets a green light, waits for verbal recognition, and says the answer. Because we had never practiced with a buzzer system of any kind (mostly because professional systems cost $300+), we got many misfires and “blurts” on our side, resulting in lost points all over the place.
Last year we placed second in the entire competition with close to zero practice. This year, I took the challenge of building us a lockout-style buzzer system that would allow us to get the feel for the real thing beforehand. It ended up costing half of what a professional unit would have cost, and is much lighter and easier to use, as well.
The circuit is a simple 8-channel lockout setup. The first player to hit the button activates his/her channel, rendering all other channels incapable of activating. Later I added on a monostable one-shot timer circuit to power an audible buzzer, which turns on the buzzer for only a predetermined amount of time after a player buzzes in. This makes it easier to distinguish the exact moment that a player buzzes.
I used a combination of parts on hand, parts bought over the net (eBay) and parts bought in- store at the local Radio Shack. I designed all circuit boards myself, and ended up tracing them all by hand, as well. It took over 24 straight hours of work and $150 to complete, but I’m very satisfied with the design. It’s simple, solid, and the best part is, NO MICROCONTROLLERS! Yep; simple analog circuitry at it’s finest.
Complete photo gallery below: