Electronic basics: using a multimeter

How to use a multimeter to measure voltage, current and resistance

A digital multimeter is a convenient tool, one of the few tools you need to use to get started.

There are many kinds of multimeters, from very cheap multimeters (about 10 US dollars) to this price, it is very cheap to buy, but there are also very cheap feelings:

Unless you are using a very professional product line (no need to start), you can get a good product line for less than $30.

I paid the 30 dollars and did a good job:

Between these two, there are big differences in size and build quality:

You can also see a10APort, the other has one20Aport. This means that before disconnecting the fuse, one person can measure up to 20 amps and the other half can measure.

The larger one mA port can measure a maximum current of 500 mA, and the smaller one can measure a current of 200 mA.

Similarly, people can also use a special cable to measure temperature. It has a light, and so on.

Digital multimeter can measure voltage (Voltmeter), current(Electric meter),Revolt(Ohmmeter), capacity, frequency, etc.

It has many built-in tools.

I will show you how to measure the first three things.

How to measure voltage

Let's start with the measurementVoltage. Take the battery, connect and chooseVSymbol:

And connect the black connector toCOM, Common ground and red connectorVSymbol and connect the other end of the cable to+with-Battery terminal:

How to measure resistance

Now let us see how to measure resistance.

Connect the two cables to both ends of the resistor and selectSymbols on the multimeter:

This is a 220Ω resistor.

This is the same measurement made on a cheap multimeter:

Note that we didn't have to set the scale before, it was determined automatically. Here, if the resistance is too low or too high for the scale, you need to fine-tune between the resistances.200 2000 20k 200k 2000kPoint out which can bring you meaningful results.

For example, here I chose20kScale, i got0.22On the display.20kMeans it can measure at most20kΩ. In this case, 0.22 is expressed as 0.22 of 1kΩ:

It's a bit confusing, right? This is not the best choice, so I suggest you choose a multimeter that can automatically determine the scale.

How to measure current

I showed you how to measure voltage and resistance first, because they work similarly: the connector is placed parallel to the item we want to measure.

measuringcurrentIs different. We need to connect the multimeter in series so that the current flows through it.

Also, depending on your multimeter, you may need to change the entry point of the cable. In this case, I use input #4 to measure volts and Ω, but use input #1 (and a lot of current through input #2) to measure current:

In order to measure the current, let us build a small circuit. In this case, I have a potentiometer that can light up the LED.

Two cables connect the LED cathode to the lead that closes the circuit to GND. This is important: do not measure the current flowing through the element by connecting the multimeter directly to its cable. You need to make the multimeter part of the circuit.

The multimeter acts as a wire.

On the multimeter, you can select the scale of the current measurement. We set it tomA, But try to switch touAMeasure in microamperes instead of milliamperes:

You got it753uA,equal0.753mA.

This is the same measurement made with a yellow multimeter, in this case, the ports used to measure small currents are the same as the ports we used for voltage and resistance:

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