AC touchswitch

Many designs for touchswitches have pre- viously been featured in Elektor. However, most of t)}ese operated on skin resistance and thus required a double contact that could be bridged by a finger. Single contact operation is possible using a capacitive pick- up of mains hum, but this is not very reliable, -and will not worjc at all with battery- powered equipment! The design given here overcomes these difficulties and provides a reliable single-point touch switch.