Multimeter Symbols: What do They Mean?
Multimeters are incredibly useful tools that are helpful for a wide range of tests and measurements. If you ever deal with electricity, a quality multimeter is a must-have item. They’re fairly simple to use, but the symbols on the front of these devices almost appear to be hieroglyphs! If you don’t speak the language of multimeter symbols, they can be quite difficult to decipher. Luckily, we’ve put together this list of the 20 multimeter symbols that you must know to successfully use one of these versatile tools.
1. DC Voltage
DC stands for direct current. DC voltage will allow you to measure the voltage of direct current electronics. This includes most small electrical circuits such as batteries and indicator lights. You’ll also use DC voltage when working on a vehicle.
2. AC Voltage
This is the setting you’ll use most when working on electrical circuits that are hooked to the grid. In the US, you’ll mostly be measuring AC voltage between 110V and 240V.
Millivolts measure fractions of a volt. If you’re dealing with low-voltage circuits, you’ll probably use the millivolts reading rather than the standard voltage selection.
Called amps for short, amperes measure electrical current. You can think of the current as the total amount of electricity moving through a circuit.
A milliamp is 1/1000 of a standard amp. When you’re measuring a low-current electrical circuit, you’ll want to switch from amps to milliamps to get an accurate reading.
Microamps are even smaller than milliamps. While a milliamp is one-thousandth of an amp, a microamp is one-millionth of an amp and it’s used for measuring the lowest current circuits. You might use microamps for measuring extremely low power microcontrollers or tiny electronics, but you won’t often use microamps when dealing with household or automotive circuits.
Resistance is a measurement of how much opposition a circuit or object puts up against the flow of electricity, and it’s reported in ohms. Materials with high resistance restrict electrons from flowing, while items with low resistance allow the electrons to flow freely. Conductors like metal have low resistance. Insulators such as rubber have high resistance.
When ohms just aren’t going to describe the high amount of resistance in a system, you’ll need to switch to kilo-ohms. A single kilo-ohm is equal to 1,000 ohms.
Megohms are the next step up from kilo-ohms when discussing resistance. A megohm is 1,000 times larger than a kilo-ohm. One megohm is equal to one million ohms.
10. Continuity Beeper
Continuity testing makes it quick and easy to tell whether or not a circuit is live. A continuity beeper will make an audible alert to signal a hot circuit, signifying that you need to kill the power before cutting into those wires!
Capacitors are devices that collect and store electrical energy. When using the capacitance setting on a multimeter, you can easily measure how much energy a capacitor is holding. Capacitance is measured in farads, though you’ll usually need to use fractions of a farad to express the measurement.
A microfarad equals one-millionth of a farad, and it’s the most common way you’ll measure capacitance with a multimeter.
Nanofarads are even smaller units of capacitance than microfarads, measuring one-billionth of a farad of capacitance.
14. Diode Test
A diode test measures the voltage drop across a diode. When you set the multimeter to this setting, the test leads will produce a small voltage. Touching them to the proper sides of the diode will cause the voltage to flow through, allowing the meter to measure the difference between input and output.
Hertz is a measurement of frequency that equals one cycle per second. Circuits can use fixed or variable frequencies, and you’ll want to know which you’re dealing with when measuring frequency.
Relative mode allows you to zero out the multimeter using a measurement you’ve previously taken. This makes it easy to compare additional measurements to the first one, which is incredibly useful for things such as measuring the voltage drop across a system. For instance, you can measure the voltage at your home’s electrical panel, then hit the relative button. When you measure the voltage at an outlet, you’ll be shown the difference between the original measurement and the voltage at the outlet.
17. Manual Range Override
This isn’t a feature you’ll find on every multimeter. It allows you to override the auto-ranging functionality of your multimeter to manually set the range you wish to measure.
The hold function is designed to capture and hold the reading on your screen. Press the button while taking a measurement and the measurement will remain on the screen. Some multimeters have an auto-hold function that does even better. On auto-hold, the meter will find the most stable measurement and will hold that, allowing you to work with both hands on the leads.
19. Min and Max
When you enter the min/max setting on a multimeter, you’ll notice that the display no longer changes with the voltage. Instead, it will save the highest reading and continue to display it. If you press the button again, you’ll see the lowest reading that the meter has taken since you entered min/max mode. This allows you to take multiple measurements in a row and quickly see what the lowest and highest readings were.
If your multimeter starts to display this caution symbol, you’ll need to reference the user manual to see what the problem is. But make sure you do this right away before continuing to take electrical readings, for your own safety’s sake.
When you first look at the front of that new multimeter, all of those symbols seem like a language that you don’t speak, and it can feel pretty daunting. Hopefully, we’ve been able to clarify those symbols and remove a bit of the mysticism so you can get to work without the worry that you’re reading something wrong. Refer back to this list anytime you need a refresher or you’ve forgotten what one of the many symbols on your multimeter indicates.
Featured Image Credit: CC0 Public Domain, Pxhere