- Time Required: A Weekend
- Cost: $25–$150
Learning about technology is a lot easier when you’re having fun — and shooting at targets is fun! With this amusement park-style arcade, you’ll fire beams of infrared light instead of projectiles to trigger automated knock-down targets you can customize with soda cans, ducks, robots, or anything else you feel like toppling with a well-placed shot.
Here’s how to build it from scratch, using inexpensive AVR microcontroller chips you can program yourself from any computer.
How It Works
The toy gun emits invisible infrared (IR) light from an IR LED. The LED’s light spreads at a wide angle, which makes aiming too easy — so we mount it deep inside a tube to collimate its light into a narrower beam.
This infrared light is similar to that of a light bulb or sunshine. To make the gun’s light unique, we program the gun’s microcontroller to switch the LED on and off 38 thousand times a second (38kHz), a frequency that doesn’t normally occur in background light.
Each target has an IR receiver that uses a phototransistor to see infrared light. When the target’s microcontroller detects the 38kHz signal from the gun, it triggers a servomotor to knock the target down.