After having his mints disappear for quite some time [Quinn Dunki] came up with an idea to get back a the fresh-breath thieves. A bit of circuit design, parts scavenging, and free-form construction led to the creation of his mint-tin burglar system.
Here’s how it works. Flip the on/off switch in the base of the mint tin before you head off for lunch or a coffee break. When the foul-mouthed pilferer hits up your stash they’ll get what they were looking for at first. But by opening the tin they tripped a timer circuit that will send the mints vibrating across the table soon after having been opened.
The breadboard above holds the prototype timer circuit, built around or friend the 555 timer. The vibration motor from a cellphone is a perfect choice for this hack as it’s very small and is just waiting to run from a low-voltage source. We especially liked the use of the cells from inside a 9V battery as a power source and the compact assembly that manages to fit inside the mint container.