Hacking With Gum

Sometimes when working on a project you may find that you need a vibration sensor. These are useful for detecting footsteps, tremors, wind, etc. Accelorometers can be used, but are a costly solution if you simply want to detect vibrations and are not concerned with gathering precise measurements. Out of curiosity one day, I cut open an Urchin ball to examine the circuitry they use for detecting vibrations / shock. I found that they use a light spring as a very simple, but effective, shock sensor:

Urchin Ball Spring Shock Sensor

The above circuit is enclosed in a small hard plastic ball, placed inside the Urchin ball, which prevents the spring from being physically struck as the ball is thrown around. When the spring vibrates, it strikes the pad on the circuit board, completing a connection and initiating the flashing light sequence. By adjusting the height of the spring above the pad, the vibration detector can be made quite sensitive; even a slight tap on the table or a gentle breeze will set it off:

Just goes to show that you shouldn’t over think your problem: the simplest solution is usually best. I’m thinking that I’ll have to use this for something this holloween…