how to use a multimeter

How to use a Multimeter

Introduction

So how to use a multimeter? In this tutorial we will show you how to use digital multimeter. In the other terms you can say Digital Multimeter as a DMM. This is very useful to test your electronics circuit. Troubleshoot electronics fault also used as a measure a electronics components. It can aslo use to measure line voltage also battery voltage. You can say it is an multi purpose device that can do many things.

The common basic parameters we measure that are voltage and current. A multimeter is also great for some basic sanity checks and troubleshooting. Is your circuit not working? Also for the switch or work? To troubleshoot the circuit problems we are using multimer as a trouble shooter.

Accessories of Multimeterhow to use multimeter

The most common accessories come with multimeter is measuring prob and battery pack. If you are purchasing multimeter from good manufacturer then they will provide also a carry case with it also holder. With the all types of multimeters are come alone with the operation and safety manuals. In the manual you will find a how to operate a multimer also some safety precaution of use. So before you start using a multimeter first refer the operating instructions and user manual.

Parts of Multimeter

Multimeter has main three parts

  • Digital Display
  • Selecting knob
  • Ports

Digital Display

The display usually has four digits and the ability to display a negative sign also. Display will show the resultant value of the your measurement. It has also battery indicator included, It will show the battery level.

Selecting knob

selector knob of multimeter

 

The selecting knob use to set the multimeter to read different things such as milliamps (mA) of current, voltage (V) and resistance (Ω) also continuity.

Ports

ports of multimter

 

Two nos. of measuring prob are usually plugged in the probes provided in the multimeter. Multimeters have a three prob are provided but in special types of multimeters have a additional extra prob provided. Generally it is provided for frequency (Hz) measurement or it will be depend on the manufacturer. COM stands for common terminal it is always connected to the ground terminal of the circuit or “-” negative terminal of the circuit. The COM probe is generally black but there is no difference between the red probe and black probe other than colour. In most of multimeter 10A port specially provided separately for measurment of the DC current up to 10A. Also this 10A prob is protected by fuse protection inside a multimeter. Also special prob provided for the lower current measurment uo to 600mA. The remaining prob is provided for the measuremnt of the Voltage (V), Resistance (Ω), frequency (Hz), continuity, etc….. The banana type connector on the end that plugs into the prob of multimeter. Any type of probe with a banana plug will work with this multimeter.

Type of prob used with Multimeter

  • Banana to Alligator clip : These are good cables for connecting to large wires or pins to the breadboard. Good for performing longer term tests where you don’t have to have to hold the probes in place while you manipulate a circuit.
  • Banana to IC hook clip : This clip will work well to connect with small ICs also with larger ICs.
  • Banana to Tweezer clip : This type of clip can used with SMD type of components.
  • Banana to Test prob : This is most common prob which is provide with multimeter.

Measuring Voltagehow to measure ac voltage in multimeter

For AC Voltage Measurement

how to measure dc voltage in multimeter

For DC Voltage Measurement

So how to use a Multimeter to measure voltage. Multimeter has a two kind of voltage measuring range one is Direct current and other one is Alternating Current range. All major electronics circuits components batteries can be measurable in Direct Current range. Other then direct current range called Alternative current range has sign of sign wave. So in multimeter you can measure a Direct current as well as Alternative current. To measure that voltage range select suitable voltage range also choose Direct current or Alternative current.

port setting in multimeter

Let’s start, First measure voltage on a 9V battery Plug in black probe into COM and the red probe into . Set selector switch to the Direct current measurement sign and set multimeter to the “20V” in the DC (direct current) range. Most all portable electronics use Direct current not alternating current. Connect the black probe to the battery’s ground or negative terminal  “-” and the red probe to positive or ‘+’. If you’ve take a new battery, you will get around 9V on the display.

Let’s measure in  AC (Alternating current) range most common multimeter have a 1000V max or 750V max voltage range capacity. Let’s change the position of the selector switch to the Alternating current measurement position. Priority of the measuring prob should remains same as measured in Direct current range. Select your suitable range of the multimeter choose closest range.

Overload

Make sure that voltage which you want to measure should not exceed safe limit of the multimeter. To know the safety level of the voltage please refer your multimeter’s user manual.

What happens if you select a voltage range that is too low for the voltage you want to measure? Nothing to worry. The meter will simply display a 1 on display. This is the meter trying to tell you that it is overloaded or out of range. Whatever you’re trying to measure is too much for that particular setting. Try to change the multimeter selector knob to the next highest setting.

Warning

In general to measure DC voltage put selector switch on strait line not on curvy line. Many multimeters can measure AC as well as DC voltage in same range. But AC voltage is very dangerous please take care before measuring . Make sure you should read user manual before its use. Prob used to measure the voltage should be good quality not punched. Use safety shoes and accessories when you are working on high voltage line

Measuring Resistance

Now how to use a multimeter to measure resistance. In general normal resistor have color code on it, if you don’t know then it’s OK.  There are many online free calculators available, that can gives you value of resistor depends on its color coding. The multimeter is best tool to measure resistance at easy way.

how to measure resistance with multiimeter

 

Take any random resistor put selector switch on Ohm (Ω) and select appropriate range of the resistance. Then hold the probes on the resistor legs with the same little of pressure you when pressing a key on a keyboard. To measure the resistance prob setting will be as same as used in measurement of the voltage.

port setting in multimeter

Then meter will show one of this three things, 0.001, or the actual resistor value.

That means if multimeter will show 0.00 that means resistor open from inside, in other terms it is faulty or not working. If multimeter will show the value it means the value of resistor is too high then range you have selected on multimeter. If multimeter show you the value on display that means you have selected proper range on multimeter.

how to measure resistor with multimeter

Take a 100k Ω resistor to measure the resistance using a multimeter. first we selected  range up to 500 Ω but our resistor’s value is 100 kΩ, so it shows a over load. Next we change multimeter range to the Auto selection range. Now multimeter will the value of the resistor. The meter will show the reading of 99 kΩ, it means our selected range is proper. Like wise you have to select proper range in multimeter to measure the resistor. If you don’t know the proper value of the resistor you can measure any type of resistor in Auto selection range.

!! Take Note : If you want to measure the resistor which is built in circuit, first remove the resistor from the circuit and then measure the resistor. Never measure resistor in live circuit, first dismantle power supply then measure the resistor.

Continuity

If there is very low value of  resistance between two electrical connections which is electrically connected. At that point very low resistance between that electrical connection. Continuity testing mostly used for to check the internal connections of the electronic circuit of fuse or resistors. To check the continuity of the circuit set the multimeter on Ω value and select range of continuity. The symbol of continuity like a buzzer.

how to check continuity using multimeter

Now touch the probes together buzzer will sound a tone and display will show the almost zero reading. That means that a very small amount of current is passing without resistance  between probes. Now you can see the 2.5 Ω resistance shown on the display that means almost around the zero resistance.

how to check continuity using multimeter

Breadboard that is not powered. Use the probes to joint at two separate ground pins. You will hear a tone indicating that they are internally connected. Joint probes from the VCC pin on a microcontroller to VCC of your power supply. It should sound a tone indicate that power can flow from power supply to micro controller. If there is does not sound a tone, that means there is something wrong connections.

Measuring Current

Reading current is one of the most tricky readings in the electrical world. Because you are measuring current in series circuit. Where voltage is measure between VCC and GND or you can say in parallel . To measure current you have to physically break the flow of current and put the meter in-line with circuit.

The first thing you will need is an extra piece of wire. As mentioned you have to break the circuit to measure the current. First connect VCC to the resistor then end of the resistor connect to the red wire of the multimeter . Then COM wire of the multimeter will connected to the power supply. This will “breaks” power supply to the circuit. Then we will insert the multimeter in series connection so that can measure the current.

how to measure current using multimeter

In the multimeter now set the selector switch to the proper setting and measure some current. Measuring current is likely the same as voltage and resistance. You have to choose correct range. Set the multimeter to 200mA or 10A range also select port as per need. The current consumption of many small breadboard projects is usually around 200mA. Make sure the red probe is plugged into the fuse protected port. This means you can keep the red probe in the protected port to measure current. However, if you . Overloading the current can result blow fuse rather than just an overload display.

Remember: If your system use more than 100mA you should start with the red probe plugged into the 10A port and set to 10A knob setting.

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