of construction within the volume constraints of sensor housing 15 and they generate an electrical signal responsive to the presence of a human hand or other body member housing 15 is preferably kept quite small having an outer diameter of less than 3 inches and a thickness of less than 1 inch with a total weight preferably of only a few ounces fig5 diagrammatically shows a typical electronic circuit usable in the present invention sensor element 38 is connected to a suitable amplifier 40 which has electrically balanced circuit components attached thereto so as to generate an output signal representative of the loading effect of sensor element 38 together with any external circuit loading members the output signal from amplifier 40 is fed into a converter circuit 42 which generates a signal representative of loading changes which have been sensed by amplifier 40 the output signal from converter circuit 42 is coupled to a switching or threshold circuit 44 which generates an output signal only when the external loading exceeds predetermined values thus the signal from threshold circuit 44 is representative of loading changes in excess of predetermined amounts and is therefore related to the closeness or proximity of an external member in relationship to sensor 38 the output signal from threshold circuit 44 is.