Which Multimeter Do You Need?By Jack Arcade
Multimeter Buyers GuideBe it a small electronic connection or a large complicated circuit, every component ranging from a simple diode to a complex power amplifier needs to be tested for electrical properties. A multimeter is an electronics designer's primary quality control tool, and yet making sure you have the right meter at the right price might take some planning.
Multimeters are electronic devices that measure voltage, current and resistance. Although there are many different types of multimeters with different functions and benefits, your first consideration should be analog or digital.
Velleman Analog Multimeter
Analog Versus DigitalAnalog multimeters, as you would suspect, use classic analog dials for measuring voltage, current and resistance. These are certainly more primitive and are rarely used these days, however some would argue that the analog meters are more sensitive than their digital counterparts and they are still preferred by many. After the slightest change in DC voltage, the needle on an analog multimeter can deflect, which affects the accuracy of measurement readings and might not be something you see on a digital meter. If you are dealing with circuits with highly sensitive measurements, an analog multimeter might be right for your needs.
Today's world, on the other hand, is dominated by digital multimeters (DMMs). They typically consist of an LCD display, a knob to select various ranges, an analog to digital convertor, and internal circuitry for signal conditioning.
Generally speaking, we recommend DMMs, but there are still hundreds of models to choose from, so you need to filter down your options and consider various factors when selecting the correct DMM for you. Here are some things to keep in mind:
Digital Multimeter LCD Display
PriceDMMs are available in a wide range of prices staring from $10 and going up to $1500. This depends on the brand and the included features. Higher priced meters tend to be more durable and accurate than the lower priced models. Workbench multimeters tend to be more expensive when compared to a Handheld DMM.
In general, we recommend looking at how frequently you will use the device and the features you need. If this is an occasional tool, a lower priced unit is probably fine. But, the more you plan to use the meter, the more you'll want a robust design and more expensive meter.
Display CountsThe resolution of a meter, or display counts, is the smallest part of the scale which can be shown and is scale dependent. It refers to how large of a number the meter can display or the total digits that are displayed. The higher the display count, the better. Compare multimeters with display counts of more than 1,000.
Versatility in Measurements and FunctionalityBasic multimeters have standard features such as measuring AC and DC current, voltages, resistance and capacitance. Other meters offer various tests (diode test, battery test, continuity test, transistor test) and special functions (auto range, analog bar graph, RS-232 PC interface, true RMS), which makes them more useful than a standard multimeter. Check out the device's user manual to review the functions offered and select your meter accordingly.
SafetyWhen dealing with high voltages, it's very important to know which meter you should use. Based on the amount of current flowing through the conductor, you may want to choose a device that's a cross between a multimeter and a clamp meter.
Clamp MetersCreated as a single purpose test tool for electricians, the clamp meter is an electrical tester that combines a voltmeter with a clamp-type current meter. Clamp meters have an integrated transformer for the sole purpose of measuring current, which they can measure to the nearest tenth of a unit.
Unlike a multimeter, the clamp meter doesn't need to be connected to the circuit in order to measure current. All you need to do is place the clamp around a live wire to measure the current without interrupting the operation of the circuit. Clamp meters are ideal for electrical work as they can measure large AC currents.
Check the manufacturer's manual to see which models are suitable for which categories (CAT). The lower the CAT number, the lesser the protection.
Fluke Clamp Meter
- CAT I is for measurement of voltages from specially protected secondary circuits.
- CAT II refers to local level electrical distribution, such as from a standard wall outlet or plug in load.
- CAT III refers to measurements on hard-wired equipment in fixed installations, distribution boards and circuit breakers. The Fluke True-RMS Clamp Meter and Extech Electronics AC Power Clamp Meter are suitable for a CAT III safety rating.
- CAT IV refers to the origin of installation or utility level measurements on primary over-current protection devices and on ripple control units. The Fluke 324 Clamp Meter is suitable for a CAT IV 300V safety rating.
Still not sure what meter to buy? Call us at 800-831-4242 and we would be happy to help.
Jack Arcade earned his master's degree in Mechanical Engineering from Santa Clara University. He specializes in the design and control of robots. Jack's interests include traveling, camping, trekking, river rafting, bungee jumping and mountain climbing.