Source: Nootropic Design
The Defusable Clock is a fully-functional alarm clock just like you’d expect (a normal beeping alarm, snooze alarm, etc.). But at any time you can press the big red button to start a scary countdown sequence exactly like bombs in Hollywood movies. There are 4 wires across the top of the clock. You have 10 seconds to choose the correct wire to cut: one wire stops the countdown and saves the day, two have no effect, and one will “detonate” the device immediately. These role of each wire is randomly assigned when the detonate button is pressed, so it’s a new challenge every time. Also, the wires are attached with screw terminals, so you can replace them easily.
The microcontroller is an ATmega328 with the Arduino bootloader, so this clock is programmable with the Arduino IDE. The ATmega328 is certainly more powerful than needed for a clock, but this device has lots of inputs/outputs, and ATmega328 chips are now about the same price as the older ATmega168. It keeps very accurate time and requires a simple 9V “wall wart” power adapter. A special alarm mode lets you even use the countdown sequence as the alarm and require it to be defused when you wake up in the morning.