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Countdown timer - 2014

Small gadget purposefully similar to a movie bomb countdown timer. For halloween and other occasions. Disclaimer: noone got hurt using my device.

Countdown timer

When you turn it on, it starts counting down 10 minutes (9.59.99). Time is displayed on five 7-segment displays. Have you noticed the big red button? Well... if you press it countdown will substract 1 minute.

And what fun would it be without 2 wires! One stops the timer and one significantly speeds up the countdown.

On its own it looks quite friendly, but mount it on a box with a piece of tape and you get much, much scarier device... Mu-ha-ha-ha:)

Countdown timer

Inside is Atmega8, 4 AAA batteries, 5 7-segment displays, some transistors for driving the segment displays and a power switch.

Schematic, board and firmare here