Monitoring apparatus

Abstract

A monitoring apparatus, which reads a number of internal combustion engine temperatures and engine revolutions per minute, displays either a current or a peak reading of one of these parameters using a digital readout. Transducers convert the various physical parameters to analog voltages. A digital potentiometer, comparator and logic circuitry are used to step the potentiometer output to a greater value only to equal the highest input voltage. This stores the peak voltage for that parameter in analog form. Each parameter has this equipment, which results in all of the parameters having the peak value tracked simultaneously. A multiplexer selects one of the parameters, either peak or current. This selected parameter is then converted by an analog to digital converter to a set of four binary coded decimal numbers. These numbers are then displayed on a liquid crystal display. A unique control arrangement allows a single spring loaded switch to either toggle the readout between the peak or current values, when it is held closed for four seconds, or to step the multiplexer through the various parameters when it is closed momentarily.