What are the four main settings when reading multimeter

What are the four main settings when reading multimeter

At first glance, multimeters are far from simple. In addition to symbols for standard electrical measurements (volts, amps and resistance), the multimeter dial has cryptic-looking DC and AC current symbols, several sockets for connecting the multimeter probe, possible additional functions such as a continuity test or diode tester, and sometimes a measurement scale that ranges from tiny to huge.

Warning

A quick review of volts, amps and ohms.

Before using a multimeter it is important to understand some basic concepts about electricity.

Volts are used to measure voltage, which is the force that "pushes" electrons through a circuit. If we use the popular analogy of comparing electricity to water flowing through a pipe, volts are the amount of water pressure.

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Ampere (abbreviated A) represents current, or the number of electrons flowing through a circuit. In the water analogy, it would be the amount of water flowing through a pipe.

Ohms measure the resistance in a circuit; the higher the resistance, the more the circuit slows the flow of current, just as an obstruction in a pipe slows the flow of water.

Understanding the symbols on a multimeter

Okay, back to those mysterious symbols on the scale of your multimeter. There isn't room to write down all their meanings, so manufacturers use abbreviations. Every multimeter is a little different, so the manual is always your best friend, but you can find these abbreviations for electrical measurements on most multimeters.

Voltage: V

Amperage: A

Ohms: Ω

You may also see prefixes to help abbreviate very large (or very small) numbers. These are the same prefixes used to change metric reference measurements, such as meters and grams.

μ: Greek letter Mu; means "micro" or "parts per million".

m: stands for "milli" or "one thousandth".

k: stands for "kilogram" or "thousand".

M: means "mega" or "million".

For example, 200 millivolts is read as "200 millivolts," or written as 1/200,000 volts.

What about alternating current and direct current?

Your multimeter has different settings for measuring direct current (DC) and alternating current (AC), so they have their own symbols on the multimeter.

AC is indicated by a wavy line or ~ symbol above or next to the instrument symbol. The corresponding DC symbol is a solid or dashed line, - or --------------. For example, the AC amperage symbol may be shown as ~A, A~ or Ã, while the DC voltage symbol will have a straight line (or a combination of straight and dashed lines) next to or above the "V" indicating the voltage.... DC current flows in one direction only, from almost all battery-operated objects. Alternating current changes direction many times per second.

Your multimeter may also have the letters AC or DC before or after the "V" for volts or "A" for amps. For example, ACV/VAC for AC voltage and DCA/ADC for DC amps.

Warning

Other multimeter functions

But wait, there's more. Your multimeter may also have other functions, such as the continuity test, in which a loud beep sounds when two things are electrically connected or, in other words, form a complete circuit. The continuity symbol usually appears on the multimeter as a series of parallel arcs, similar to the standard "WiFi" symbol on a laptop or smartphone. The multimeter will beep when the circuit is closed; if the component under test is not electrically connected, it will be silent.

Some multimeters can also test diodes, which act as one-way valves, allowing current to flow in only one direction. (A typical diode test symbol looks like a blunt arrow with a vertical bar on the end.) Some multimeters are even capable of testing other electrical components, such as transistors or capacitors. In any case, refer to the instruction manual.

Adjusting the multimeter scale

Once you have understood the abbreviations and settings of your multimeter, you are ready to use it. First, decide whether you want to measure volts (V), amps (A) or ohms (Ω), and whether it is AC or DC current, and then set the dial to the appropriate position.

If your multimeter is "auto-ranging," that is, it automatically recognizes the measurement scale, scaling is relatively straightforward. However, if your multimeter is "manual ranging," i.e., it should give you a rough idea of the size of the measurement, each segment of your scale can be divided into different scales or units of measurement.

To ensure accurate measurements, set the scale a little higher than you expect, but not so high that the reading is an imperceptible dot at the bottom of the scale. For example, if you are measuring a 15V circuit and your multimeter has 2V, 20V and 200V settings, you would choose the 20V setting.

Using the multimeter: connecting the probe

Your multimeter comes with leads with either red or black probe terminals. Like car wire terminals, the red probe tip or terminal corresponds to the positive terminal of the circuit, while the black probe tip or terminal corresponds to the negative terminal or wire.

Your multimeter usually has one ground tap for the black/negative probe (sometimes labeled "COM"), but there may be several taps for the red/positive probe. These sockets are marked with the unit of measurement (volts, amps, or ohms) and may also be marked with a scale; for example, there may be one socket for measuring volts and another for measuring millivolts. Always take care to choose a socket that corresponds to the unit in which you wish to measure and is slightly larger than the intended scale.

To connect the multimeter

Once you have connected the probe to the multimeter and set the multimeter scale correctly, you can connect the multimeter to the circuit you want to test. How you connect it depends on what you want to measure: to measure voltage, connect the probe tip in parallel with the circuit, placing the positive probe on the positive side of the circuit and the negative probe on the negative side of the circuit (see the resources section for an explanation of series and parallel connections).

To measure current or amperage, disconnect the power supply, connect the multimeter "in-line" or in series with the object to be tested, then reconnect the power supply and test the circuit.

To measure the resistance of an object in a circuit, disconnect the object completely from the circuit and any power source, then connect or touch the multimeter's red and black test leads to either side or both ends of the object.