A Laboratory Kit for Multimeter Design

The multimeter is an important electrical tool and is a combination of many individual instruments. In practice, common multimeter designs are digital and measure voltage, current, resistance, capacitance, etc., using a single set of probes. Before the digital age, the world relied on analog displays. Some argue that analog displays are outdated technology. However, this overlooks one of the most important characteristics provided by the analog display, which is its ability to provide an instantaneous visual perception. Analog displays are currently used for many applications in aviation and automobiles, demonstrating their continuing usefulness in the field. In the multimeter, the analog display is based on an electromechanical device called a galvanometer. Externally, the galvanometer consists of an incrementally marked face and a needle indicator, similar to that of a clock or tachometer. The deflection of a needle indicates the intensity of the flow of a very small direct current passing through the device. This project utilizes a galvanometer, a ribbon cable with a breadboard connector, 3 external terminals, a 12-position switch and a fuse, within a 3D-printed enclosure to produce a kit for laboratory experiments. Students use the kit to design a multi-scale DC voltmeter, DC ammeter, AC voltmeter, and Ohmmeter. Finally, the kit allows the use of an internal printed circuit board instead of an external prototyping board for a completely enclosed multimeter implementation.