Abstract: A sensing apparatus wherein a photoelectronic transducer and a light-emitting diode are adjacent to one end face of a bundle of fiber optics. The other end face of the bundle is located in the housing of an actuator wherein a reciprocable plunger can move a light absorbing or light reflecting element into and from the path of light issuing from the bundle. The position of such element influences the amount of light which is reflected back into the conductor to ensure that the signal which is generated by the transducer is indicative of the amount of reflected light. The transducer can transmit signals to a signal receiving device which, in turn, can influence the intensity of light issuing from the diode in dependency upon whether or not the device receives a signal from the transducer. The actuator can be installed in an area which is not explosion-proof or in an area which is exposed to pronounced electrical noise.

Abstract: A pulse-rate indicator having electro-optical means for converting pulse beats into electric measuring pulses, means for generating a number of timing pulses derived from measuring pulses, means for calculating the pulse-rate from the number of timing pulses, means for displaying the pulse-rate, and a pushbutton for rendering the indicator operative, the electro-optical means being disposed in the pushbutton for generating the electric measuring pulses as a function of the perfusion of blood in a human fingertip pressing upon the pushbutton.