Here’s your useful and beautiful circuit for the day — [New Pew]’s vibration sensor takes manual control of the flip-flop inside a 555 timer and lights an LED in response. Use it to detect those vibrations you expect, like laundry machines, or those you only suspect, like the kind that might be coming from your engine. This gadget isn’t super-precise, but it will probably get the job done.
The vibration-detecting bit is a tiny ball bearing soldered to the spring from an old pen, which is tied between the trigger and ground pins of the 555. When the chip is powered with a 9 V battery, nearby vibrations will induce wiggle in the spring, causing the ball bearing to contact the brass rod and completing the circuit. When this happens, the internal flip flop’s output goes high, which turns on the LED. Then the flip flop must be reset with a momentary button. Check out the build video after the break.
Want to pick up Earthly vibrations? You can detect earthquakes with a homemade variable capacitor, a 555, and a Raspberry Pi.