Abstract: A device for simulating electrical characteristics of an electrical, electronic or electromechanical component comprising circuitry (21) adapted to reproduce electrical characteristics which are produced by, or may be sensed in, the component, the device (1) being configured so as to substantially resemble the component in appearance and/or size. The device may have two substantially flat opposed surfaces (3,27), one of which carries a picture (5)of the component and the other a sectional view through the component to illustrate its technical construction or operation, and/or other data relating to the component. A kit may be provided comprising a number of such devices each to simulate a component forming part of an equipment or system so as to simulate the electrical characteristics and/or performance of the equipment or system.

Abstract: A system for simultaneously and independently controlling a plurality of electric motors from a number of dispersed stations. The system operates by transmission of duty cycle modulated selected frequencies superimposed on a DC track voltage on a common power line servicing the motors. The modulation is variable and determines the speed of the motors. Transmitters are portable and designed removably to plug into a common signal transmission cable anywhere along its length without interaction. Receivers, each tuned to a specific frequency and associated with and controlling a motor, are coupled to the common power line.