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How to Use a Multimeter to Test a C Amps

Updated on: December 7, 2018

Overview

This tutorial will reveal you just how to make use of a digital multimeter (DMM), a vital tool that you can use to diagnose circuits, find out about other individuals’s electronic styles, and also test a C amps. Therefore the ‘multi’-‘meter’ or several dimension name.

The most basic things we measure are voltage and current. A multimeter is additionally excellent for some standard sanity checks as well as troubleshooting. Is your circuit not functioning? Does the button work? Put a meter on it! The multimeter is your very first protection when repairing a system. In this tutorial we will certainly cover measuring voltage, current, resistance and also continuity.

Every fixer must know their method around a multimeter, which has just north of a zillion makes use of for screening digital parts and also circuits.

In this tutorial we’re mostly likely to show you exactly how to use a multimeter. This tutorial is mainly addressed for newbies who are starting in electronic devices as well as have no concept how to utilize a multimeter and just how it can be beneficial. We’ll explore the most common functions on a multimeter and exactly how to measure current, voltage, resistance and also how to inspect continuity.

What is a multimeter and why do you need one?

A multimeter is a measurement tool absolutely necessary in electronics. It integrates three necessary features: a voltmeter, ohmeter, and ammeter, as well as sometimes continuity.

The tool permits you to understand what is going on in your circuits. Whenever something in your circuit isn’t working, it will aid you repairing. Below’s some scenarios in electronic devices projects that you’ll locate the multimeter useful:

  • is the button on?
  • is this wire performing the electrical energy or is it broken?
  • just how much current is flowing with this led?
  • how much power do you have left on your batteries?

What could multimeters measure?

Virtually all multimeters can measure voltage, current, and also resistance.

A handful of multimeters have a continuity check, leading to a loud beep if two things are electrically attached. This is helpful if, as an example, you are developing a circuit as well as linking cables or soldering; the beep indicates everything is linked and nothing has actually come loose. You can additionally utilize it to ensure 2 things are not connected, to aid protect against brief circuits.

A handful of multimeters additionally have a diode check function. A diode resembles a one-way shutoff that only lets electricity circulation in one instructions. The precise feature of the diode check can differ from one type to another. If you’re working with a diode and can not tell which means it enters the circuit, or if you’re not exactly sure the diode is functioning appropriately, the check feature can be rather useful. If your DMM has a diode check feature, reviewed the manual to find out exactly just how it works.

Advanced models may have other functions, such as the ability to measure and also identify other electric parts, like transistors or capacitors. Because not all multimeters have these features, we will not cover them in this tutorial. You can read your multimeter’s handbook if you require to make use of these features.

What Do All the Symbols Mean?

There’s a great deal taking place when you look at the selection knob, yet if you’re only going to be doing some standard stuff, you won’t even use half of all the setups. In any kind of case, below’s a review of what each sign implies:

Direct Current Voltage (DCV):In some cases it will be denoted with a V– instead. This setting is utilized to measure direct current (DC) voltage in things like batteries.
Alternating Current Voltage (ACV): Sometimes it will be denoted with a V ~ rather. This setting is made use of to measure the voltage from alternating current resources, which is quite much anything that connects right into an electrical outlet, in addition to the power coming from the electrical outlet itself.
Resistance (Ω): This gauges just how much resistance there remains in the circuit. The lower the number, the less complicated it is for the current to flow with, and also vice versa.
Continuity: Usually represented by a wave or diode sign. This merely checks whether a circuit is full by sending out a very tiny amount of current with the circuit and seeing if it makes it out the various other end. If not, after that there’s something along the circuit that’s causing a problem– discover it!
Direct Current Amperage (DCA): Similar to DCV, yet as opposed to providing you a voltage reading, it will tell you the amperage.
Straight Current Gain (hFE): This setting is to check transistors and also their DC gain, however it’s mostly pointless, given that most electrical experts as well as hobbyists will use the continuity check instead.

Your multimeter may additionally have a devoted setup for checking the amperage of AA, AAA, as well as 9V batteries. This setting is normally represented with the battery symbol.

Again, you most likely will not also utilize half of the settings shown, so do not get overwhelmed if you only know what a few of them do.

Just how to Use a Multimeter

For starters, let’s go over several of the various components of a multimeter. At the extremely basic level you have the tool itself, along with two probes, which are the black and also red wires that have plugs on one end and also metal pointers on the various other.

The tool itself has a display screen at the top, which provides you your readout, and there’s a big selection knob that you can rotate around to pick a specific setup. Each setting might also have different number worths, which are there to measure different staminas of voltages, resistances, as well as amps. So if you have your multimeter set to 20 in the DCV area, it will measure voltages up to 20 volts.

Your DMM will certainly likewise have 2 or three ports for connecting in the probes:

  • the COM port mean “Common”, and also the black probe will certainly always connect into this port.
  • VΩmA port (sometimes represented as mAVΩ) is simply an acronym for voltage, resistance, as well as current (in milliamps). This is where the red probe will connect into if you’re measuring voltage, resistance, continuity, as well as current less than 200mA.
  • the 10ADC port (occasionally represented as just 10A) is utilized whenever you’re measuring current that’s more than 200mA. If you’re not exactly sure of the current draw, begin with this port. On the other hand, you would not use this port whatsoever if you’re measuring anything apart from current.

Warning: Make certain that if you’re measuring anything with a current greater than 200mA, you plug the red probe into the 10A port, rather than the 200mA port. Otherwise you might blow the fuse that’s within the multimeters. In addition, measuring anything over 10 amps might blow a fuse or destroy the multimeter as well.

Your measurement tool could have completely separate ports for measuring amps, while the other port is particularly simply for voltage, resistance, and continuity, but many less expensive multimeters will certainly share ports.

Anyhow, let’s start actually utilizing a multimeter. We’ll be measuring the voltage of a AA battery, the current draw of a wall clock, and the continuity of a simple wire as some instances to obtain you started and also knowledgeable about making use of a multimeter.

Parts of a Multimeter

Multimeters are made up by 4 essential sections:

  • Display: this is just where the dimensions are shown
  • Selection Knob: this chooses what you want to measure
  • Ports: this is where you connect in the probes
  • Probes: a multimeter comes with 2 probes. Typically, one is red and the other is black.
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Ports

  • “COM” or “–” port is where the black probe should be attached. The COM probe is traditionally black.
  • 10A is utilized when measuring large currents, more than 200mA.
  • µAmA is made use of to measure current.
  • enables you to measure voltage and resistance and examination continuity.

COM

COM stands for common as well as is often linked to Ground or ‘-‘ of a circuit.The COM probe is conventionally black but there is no distinction between the red probe and also black probe aside from shade.

10A

10A is the unique port made use of when measuring big currents (more than 200mA).

Selection Knob

The selection knob permits the customer to establish the tool to check out different things such as milliamps (mA) of current, voltage (V) as well as resistance (Ω).

Probes

Two probes are linked into 2 of the ports on the front of the unit. The probes have a banana kind connector on completion that connects into the multimeter. Any probe with a banana plug will certainly collaborate with this meter. This permits various kinds of probes to be made use of.

Probe Types

There are several kinds of probes readily available. Right here are a few of our favorites:

  • Banana to Alligator Clips: These are wonderful cables for attaching to huge cords or pins on a breadboard. Great for carrying out longer term tests where you do not have to have to hold the probes in place while you control a circuit.
  • Banana to IC Hook: IC hooks work well on smaller sized ICs and also legs of ICs.
  • Banana to Tweezers: Tweezers come in handy if you are requiring to check SMD parts.
  • Banana to Test Probes: If you ever break a probe, they are low-cost to replace!

Measuring Voltage

To begin, let’s measure voltage on a AA battery: Plug the black probe right into COM and the red probe right into mAVΩ. Set to “2V” in the DC (straight current) range. Nearly all mobile electronics utilize straight current), not alternating current. Link the black probe to the battery’s ground or ‘-‘ and also the red probe to power or ‘+’. Squeeze the probes with a little pressure versus the favorable and also adverse terminals of the AA battery. If you’ve got a fresh battery, you ought to see around 1.5 V on the display screen (this battery is brand name brand-new, so its voltage is somewhat more than 1.5 V).

You might measure DC voltage or AC voltage. The V with a straight line indicates DC voltage. The V with the curly line implies AC voltage.

Measuring voltage

  1. Set the setting to V with a wavy line if you’re measuring AC voltage or to the V with a straight line if you’re measuring DC voltage.
  2. Ensure the red probe is linked to the port with a V alongside it.
  3. Attach the red probe to the silver lining of your component, which is where the current is coming from.
  4. Attach the COM probe to the other side of your component.
  5. Review the value on the display screen.

Tip: to measure voltage you have to link your multimeter in parallel with the component you want to measure the voltage. Putting the multimeter in parallel is positioning each probe along the leads of the component you wish to measure the voltage.

Measuring a battery’s voltage

In this instance we’re mosting likely to measure the voltage of a 1.5 V battery. You recognize that you’ll have around 1.5 V. So, you ought to select a range with the selection knob that can check out the 1.5 V. So you should choose 2V in the case of this multimeter. If you obtain an autorange one, you don’t have to bother with the array you need to choose.

Begin by turning on it, connecting the probes into their corresponding ports and after that setting the selection knob to the greatest number worth in the DCV area, which in my situation is 500 volts. If you don’t know at least the voltage variety of things you’re measuring, it’s constantly an excellent concept to begin with the highest possible value initially and afterwards work your way down till you obtain an exact reading.

In this situation, we understand the AA battery has a really reduced voltage, yet we’ll start at 200 volts just for the sake of example. Next, place the black probe on the negative end of the battery and the red probe on the positive end. Have a look at the analysis on the screen. Because we have the multimeter collection to a high 200 volts, it shows “1.6” on the screen, indicating 1.6 volts.

Nonetheless, I want an even more exact analysis, so I’ll move the selection knob lower to 20 volts. Right here, you can see that we have an even more accurate analysis that hovers in between 1.60 and also 1.61 volts. If you were to ever before set the selection knob to a number value less than the voltage of the important things you’re testing, the multimeter would simply read “1”, symbolizing that it’s overloaded. So if I were to set the handle to 200 millivolts (0.2 volts), the 1.6 volts of the AA battery is as well much for the multimeter to manage at that setting.

In any instance, you could be asking why you would certainly require to check the voltage of something in the very first place. Well, in this situation with the AA battery, we’re checking to see if it has any kind of juice left. At 1.6 volts, that’s a fully-loaded battery. However, if it were to check out 1.2 volts, it’s close to being pointless.
In a more useful circumstance, you could do this sort of measuring on an automobile battery to see if it may be passing away or if the alternator (which is what charges the battery) is going negative. An analysis between 12.4-12.7 volts means that the battery remains in good condition. Anything lower and that’s proof of a dying battery. In addition, start your automobile up and also rev it up a little bit. If the voltage does not enhance to about 14 volts or so, after that it’s likely that the generator is having concerns.

Overload

What takes place if you choose a voltage setting that is as well low for the voltage you’re trying to measure? Nothing poor. The meter will merely display a 1. This is the meter trying to inform you that it is overloaded or out-of-range. Whatever you’re attempting to read is also much for that certain setting. Try altering the multimeter knob to a the following highest setup.

Selection Knob

How come does the meter knob read 20V as well as not 10V? If you’re aiming to measure a voltage less than 20V, you rely on the 20V setup. This will allow you to read from 2.00 to 19.99. The first figure on many multimeters is just able to present a ‘1’ so the varieties are limited to 19.99 as opposed to 99.99. Hence the 20V max range as opposed to 99V max variety.

Measuring Resistance

Connect the red probe into the best port and also turn the selection knob to the resistance section. After that, connect the probes to the resistor leads. The method you link the leads does not matter, the result is the very same.

Normal resistors have color codes on them. If you don’t know what they imply, that’s ok! There are a lot of on-line calculators that are very easy to utilize. Nonetheless, if you ever discover on your own without web gain access to, a multimeter is very helpful at measuring resistance.

Choose out an arbitrary resistor as well as established the multimeter to the 20kΩ setup. After that hold the probes against the resistor legs with the same amount of pressure you when pushing a key on a keyboard.

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The meter will certainly review one of three points, 0.00, 1, or the real resistor worth.

In this situation, the meter reads 0.97, suggesting this resistor has a worth of 970Ω, or about 1kΩ (remember you remain in the 20kΩ or 20,000 Ohm setting so you need to move the decimal three locations to the right or 970 Ohms).

If the multimeter reads 1 or presents OL, it’s overwhelmed. You will certainly need to attempt a greater mode such as 200kΩ mode or 2MΩ (megaohm) mode. There is no harm if this occur, it merely means the range handle requires to be readjusted.

In the event that the multimeter checks out 0.00 or virtually zero, after that you require to lower the setting to 2kΩ or 200Ω.

Keep in mind that numerous resistors have a 5% resistance. This suggests that the color codes may suggest 10,000 Ohms (10kΩ), however as a result of disparities in the production procedure a 10kΩ resistor could be as low as 9.5 kΩ or as high as 10.5 kΩ. Do not fret, it’ll work simply great as a pull-up or general resistor.

As a rule of thumb, it’s rare to see a resistor less than 1 Ohm. Bear in mind that measuring resistance is not best. Temperature level can influence the reviewing a whole lot. Also, measuring resistance of a gadget while it is physically installed in a circuit can be very challenging. The surrounding components on a circuit board can considerably impact the analysis.

The mockup generally resembles with a fundamental clock running of a AA battery. On the silver lining, the cable going from the battery to the clock is separated. We simply position our two probes in between that break to complete the circuit once again (with the red probe linked to the power source), just this moment our multimeter will certainly review out the amps that the clock is pulling, which in this situation is around 0.08 mA.

While most multimeters can additionally measure alternating current (AC), it’s not truly a good idea (especially if its online power), considering that AC can be hazardous if you end up making an error. If you need to see whether or not an outlet is working, utilize a non-contact tester instead.

To measure current you need to birth in mind that components in collection share a current. So, you require to attach your multimeter in collection with your circuit.

SUGGESTION: to position the multimeter in collection, you require to position the red probe on the lead of a component as well as the black probe on the next component lead. The multimeter acts as if it was a cable in your circuit. If you disconnect the multimeter, your circuit won’t function.

Before measuring the current, make sure that you’ve plugged at a loss probe in the appropriate port, in this case µAmA. In the instance below, the same circuit of the previous instance is utilized. The multimeter belongs to the circuit.

Continuity

If there is very reduced resistance between 2 points, which is less than a few ohms, both factors are electrically connected and also you’ll hear a constant audio. If the sound isn’t continuous or if you do not hear any kind of noise in all, it implies that what you’re testing has a faulty link or isn’t connected in any way.

CAUTION: To be able to check continuity you need to shut off the system. Switch off the power supply.

Touch the 2 probes with each other as well as, as they are attached, you’ll hear a constant sound.To examination the continuity of a cable, you just require to link each probe to the cable tips.

Continuity is a fantastic way to examine if two SMD pins are touching. If your eyes can’t see it, the multimeter is typically a great 2nd testing resource. When a system is not functioning, continuity is another thing to help repair the system.

  • Establish your multimeter to the continuity setup using the selection knob.
  • The readout on the screen will promptly read “1”, which suggests that there isn’t any continuity. This would certainly be correct since we haven’t attached the probes to anything yet.
  • Next off, ensure the circuit is unplugged and also has no power. Then link one probe to one end of the cable and also the various other probe to the various other end– no matter which probe takes place which end. If there is a complete circuit, your multimeter will either beep, reveal a “0”, or something various other than a “1”. If it still reveals a “1”, then there’s a trouble and also your circuit isn’t total.
  • You can likewise test that the continuity function deals with your multimeter by touching both probes per other. This completes the circuit and also your multimeter need to let you understand that.

A continuity test informs us whether 2 things are electrically attached: if something is continual, an electric current can flow freely from one end to the other.

If there’s no continuity, it indicates there is a break somewhere in the circuit. This could suggest anything from a blown fuse or poor solder joint to an incorrectly wired circuit.

Altering the Fuse

One of one of the most common blunders with a new multimeter is to measure current on a bread board by penetrating from VCC to GND. This will promptly brief power to ground with the multimeter creating the bread board power supply to brown out. As the current hurries via the multimeter, the internal fuse will certainly warm up and afterwards wear out as 200mA moves via it. It will certainly occur in a fraction of a second as well as with no genuine distinct or physical indication that something is wrong.

Remember that measuring current is performed in collection (disturb the VCC line to the breadboard or microcontroller to measure current). If you try to measure the current with a blown fuse, you’ll probably discover that the meter reviews ‘0.00’ and that the system doesn’t activate like it must when you connect the multimeter. This is since the inner fuse is broken and also functions as a broken cable or open.

To alter the fuse, locate your convenient dandy mini screw driver, as well as begin taking out screws. The elements and also PCB traces inside the multimeter are created to take various quantities of current. You will damage and possibly wreck your multimeter if you inadvertently push 5A through the 200mA port.

There are times where you require to measure high current gadgets like a motor or burner. Do you see the two areas to place the red probe on the front of the multimeter? 10A on the left and also mAVΩ on the right? If you attempt to measure greater than 200mA on the mAVΩ port you run the threat of blowing the fuse. Yet if you make use of the 10A port to measure current, you run a much lower danger of blowing the fuse. The trade-off is level of sensitivity. As we chatted around above, by utilizing the 10A port and handle setting, you will only be able to read to 0.01 A or 10mA. A lot of systems use greater than 10mA so the 10A setup and also port functions well enough. If you’re trying to measure really low power (micro or nano amps) the 200mA port with the 2mA, 200uA, or 20uA might be what you need.

Conclusions

You’re currently prepared to use your digital multimeter to start measuring the world around you. Feel complimentary to begin utilizing it to answer numerous concerns. A digital multimeter will respond to many inquiries concerning electronic devices.

A multimeter is a vital tool in any kind of electronic devices lab. In this guide, we’ve revealed you How To Use a Multimeter. You’ve discovered how to measure voltage, current as well as resistance, and just how to inspect continuity.