This instructable is part of the August Build Night with Jameco at the Taipei Hackerspace. During that event we were making circuits around the 555 timer IC, one basic and fun element of the electronics hacker repertoire, that have a lot of uses and very valuable to know its operation in general.
For this project, we are building a "ticking bomb", with just a few components and reusing the box we received the build night tools.
Step 1: Electronic Circuit
The principle of operation is the following: The 555 timer is driven in astable mode, that produces a series of square waves on the output. The square waves are charging and discharging a capacitor (C2) driving a current through an 8 Ohm speaker (SPKR1) for every tick. The frequency of the output waves is determined by the values of R1 and C1 - here tuned such that it has a clock-like rate.
Bill of materials:
* 555 timer
* 47kOhm resistor
* 2x10uF capacitor
* 8Ohm speaker
* 9V battery
Can use higher capacitor value for C1 to slow the ticking down (or smaller to speed it up).
We assembled it on a breadboard, but could solder it as well.
Step 2: Package and Give It to Someone
When finished with the circuit, put it in a box, make sure that the connections don't come out, and hand it over to some unsuspecting friends (or enemies).
In my experience, the ticking sounds better inside the box, than the outside of it, maybe the muffling effect of it makes it cooler.
Enjoy the "bomb", and don't ship it!