Abstract: An improved device for indicating and measuring small variations in the resistance of a living body is disclosed which utilizes a central processing unit to digitally process sensed body resistances and drive a resistance-indicating display while compensating for the effects of component aging, component tolerances and component temperatures. The device includes an automatic calibration circuit that is automatically activated on each powering up of the device to measure and store measurement values for a plurality of synthesized body resistances that are used to form a compensation model against which sensed body resistances are, subsequently compared for automatic adjustment of display driving measurement values.

Abstract: A system for measuring changes in the resistance of a living body includes a resistance measuring circuit, an amplifier circuit and an indicator circuit in which the amplifier circuit includes a calibration circuit to give a generally constant amplitude response to a given measured input. Radio frequency insulators are included to reduce noise in the system. The circuits are operated such that when an overall change in the resistance of a living body occurs, the resistance measuring circuit is adjusted to determine the overall resistance. To account for changes in sensitivity caused by the overall change in resistance, the gain of the amplifier circuit is automatically adjusted to thereby maintain a generally constant amplitude response.

Abstract: An apparatus for reducing distortion during recording in a tape recorder of the type including a recording head which includes an electrically grounded, electrically conductive member in light contact with a coated surface of the recording tape provided adjacent the recording head. With this structure, excess electrons present on the coated surface of the tape after recording are removed.