Faced with calibrating the oft-erratic run-back timers on several *noisy* shakers, I had the idea of connecting a vibration switch to a lithium-cell powered timer module: Shake the switch and the clock counts minutes & seconds...
After some thought, I mounted two sensors back-to-back.
To get them to work reliably, I just had to put a small capacitor across the contacts. I can't remember the exact value, possibly 4u7 or 10u, because I grabbed a range from 0.1 u upwards, and tried them until it worked...
FWIW, I built the timer module into a water-resistant lunch-box and used
4mm plugs/sockets and some ultra-flexible silicone DVM-probe cable to connect the parts. The sensor head tied on to the appliance with rubber bands...
The rig was sufficiently sensitive that I was later able to use it for placid 'orbital' shakers, too.
;-)
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