So sensitive that even dropping a pin can trigger it!

The old-fashioned vibration switch is well-known. This consists of a flexible lever, fixed at one end, with a small weight attached to the other. When there is vibration, the weight “bobs” slightly, knocking a terminal beneath it. Electrical contact is made, and an alarm is triggered. This type of switch usually has an adjustment screw, to adjust the gap between the weight and the terminal, thus adjusting its sensitivity.

The “super switch” project presented here simulates this old-fashioned vibration switch. As with the old switch, it too has an adjustment screw. There are just two superficial differences. First, an indicator light indicates that vibration has been detected. Second, it has three terminals instead of two – namely +VE, 0V, and OUT. The OUT terminal goes logic “high” when vibration is detected, and by means of these terminals the Super Vibration Switch may be plugged into circuits with widely varying supply voltages, from 2V to 18V.

The real difference, however, lies in its sensitivity. As simple as it is, it may justifiably be described as being “super-sensitive”. While the old-fashioned vibration switch is best suited to detecting noticeable motion, such as a bike being disturbed, or valuables being lifted, the Super Vibration Switch is capable of picking up very subtle vibrations indeed. It will easily pick up a person walkingacross a wooden floor at virtually any distance (e.g. at the far side of a hall). The author’s prototype was capable of picking up a pin striking a wooden floor at two metres distance. It reliably picked up a telephone receiver being put down in the next room, and the vibration of the neighbours car doors closing at twenty metres distance.