Digital Multimeters - A Look at Essential Parts and Basic Functions

A digital multimeter is an indispensable component of the electrical technician’s toolbox. Regardless of the make or cost, digital multimeters share many of the same functions. This article provides a brief overview of the essential parts and basic function of the typical multimeter.

Companies such as Fluke, Mastech, Tektronix, and Extech to name a few, manufacture popular brands of these digital multimeters.  These electrical measuring tools range in price from as little as $10 for the most basic models to around $5000 for top of the line units. 

Display

A digital multimeter generally has a large and intuitive display that is simple to use and easy to read.  Most displays have a four digit display, with the first being a 0 or 1, with a +/- indicator.  Some units may also have additional displays, such as an AC/DC readout.

Connections

All digital multimeters have two connections for the probe; some models may have three, four or more.  Connectors are attached to leads that are flexible, well insulated, and terminate with connectors that are appropriate for the particular meter.

The main connectors on these devices include:

1. Common connector, which is used for all measurements.  The negative (black) lead probe is usually attached to the common connection.
 
2. Voltage, ohms, and frequency connector.  This connector is used for most types of measurements.  This connector accepts the red probe.

3.  Amperage connector.  Used for measuring amps (current), this connector also takes the red probe.

The Main Switch

Every electrical measuring device needs a switch to turn the device on and off.  Digital Multimeters have one main switch used for that purpose.  The main switch is normally a single rotary switch that is used to turn on the power and select the type of measurement that will be made. 

Other Features

In addition to the above standard parts of the typical digital multimeter, there may be many other features on specific models made by different companies, such as additional displays and controls.  Some multimeters include functions for specialized applications, such as a probe for measuring temperature, scales for measurement of decibels, capacitance, transistor gain, motor windings resistance, wiring continuity, insulation tests, and so forth.

Most manufacturers keep devices fairly simple however, and offer a standard layout that is common to all their products.  This standard layout has been the norm for multimeters for many years and will likely be common for the foreseeable future - barring any new revolutionary design. 

In conclusion, it is probably safe to say that whatever form these essential electrical measuring devices take in the time to come, they are certain to be found in every electrician’s tool kit for many years to come.