Abstract: A visual indication system for easily providing information about the status of the output terminals of a solid state relay. A two-electrode neon glow lamp is connected across the output terminals of the relay in series with a current limiting resistor. The shunting impedance of the relay output terminals prevents voltage from inducing a glow in the neon lamp in certain modes of terminal configuration. When the terminals are ON, neither electrode glows. When the terminals are OFF, both electrodes glow. If the AC relay fails in a half-wave mode, only one of the electrodes will glow.

Abstract: A photoelectric perforation sensor for accurately detecting a perforation in a moving web. The sensor comprises two large photodiodes in a bi-cell configuration. The photodiodes lie in the direction of web travel. As the perforation begins to pass between an LED source and the bi-cell, light from the LED illuminates one photodiode but not the other. As the perforation becomes centered over the photodiodes, both photodiodes receive equal amounts of illumination and a signal is generated indicating location of the perforation.