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how to use a digital multimeter

by:HoldPeak     2020-01-12
The popular mechanical digital multimeter is an indispensable tool to test, diagnose and troubleshoot circuits, components, and equipment.
First digital multimeter recently launched
1970 s, more accurate and reliable than the old needle --
Based on analog instruments.
It is mainly used to measure voltage (volts), current (amps)
And resistance (ohms).
But this is just the beginning of this very useful tool.
Here are five common uses of the digital multimeter.
Note that the instructions given here apply to most multimeters.
However, depending on the features and functions of a particular device, the exact process and the way the screen is read out may be slightly different.
Warning: there may be potential hazards using power and electrical components.
Extreme safety precautions must be followed when conducting electrical measurements.
Before using the digital multimeter, be sure to read and fully understand the instructions and warnings outlined in the user manual.
Before diving into how to use the new multimeter, please read the introduction article of Fluke to learn about the multimeter.
They will give you a detailed introduction to what the multimeter is and everything it can do, and keep reading and get some tips from our favorite electrician.
Starting with the simplest and most basic test, use the voltage mode on the meter to check the battery output.
First insert the Black probe of the meter into the label-COM (common).
Insert the red probe into a marked Volt or V (
Next to V, you may also see a symbol that looks like an inverted horseshoe, which we will discuss in a minute).
Most modern meters make this setup very simple by color coding the jack.
The black ordinary detector enters the Black Jack;
The Red probe is mounted in the red jack.
Turn the rotary switch now (dial)to Volts DC;
Because the battery provides direct current (DC)
Not AC (AC).
The tip of the Red probe is positively charged with the battery (+)outward-
Shape terminal, negative to Black probe (-)inward-Terminal.
The battery voltage will be read out on the meter display.
For example, the reading of a fully charged AA battery should be at least 1. 5 volts.
You can test almost any battery from AAAs to car battery using a multimeter.
Please note that the above-
The above technique only tests the voltage, not the ability of the battery to provide current under load.
The test gives you a general idea of whether the battery is good, whether it needs to be charged.
Here\'s how to determine if your home\'s wall outlet offers the right voltage, which is 120 V in most modern homes.
Insert the Black probe into the black COM Jack of the meter and the Red probe into the red Volt Jack.
Then adjust the rotary switch to AC (Vac)
, Which is also represented by the wavy line on the dial.
Push the tip of the Red probe into the shorter one (hot)
Two vertical slots on the socket.
Insert the Black probe into a longer slot (neutral).
Check the reading on the meter screen.
The outlet that works normally shall produce a voltage of 110 to 120 volts.
Next, remove the black probe from the socket-
Leave the red probe in place.
And insert the Black probe into a small, round hole (ground)
Under two slots.
Reading should remain the same.
If not, improper wiring of the socket or loss of grounding;
Call an electrician.
Is there a problem with the ceiling light?
Here is how to determine if there is a problem with its switch.
First, turn off the switch power supply, remove the cover plate, and then unscrew the switch wire.
Label them or take photos with your phone before disconnecting the wires to make sure they are reconnected correctly.
Loosen the switch terminal screws, remove the wires from them, and then remove the switch.
Rotate the dial of the meter to the Ohm setting.
Set the resistance range to x1.
Skip this step if your meter has auto functionrange (
You can tell you there\'s an automatic
If you transfer the dial to Volts AC (Vac)
When setting, the word \"automatic\" appears on the screen).
Insert the Black probe into the COM Jack and the Red probe into the Red V Jack.
Test single-pole switch (
The simplest one.
There are two brass screws and one green screw).
Flip the switch to the off position.
Now touch the probe of the meter to the brass screw terminal on the side of the switch-it doesn\'t matter which probe touches which screw.
You should get the reading of O when the switch is off. L (
You can also get other readings such as 99999 or symbol I like this, even this: L).
This means that the over load or over limit, the resistance is too high to be measured.
It doesn\'t seem to make sense at first (
You would think the meter reading is zero ohm)
, But the meter tells you that when there is no internal contact inside the switch, the resistance on the open contact is too large and the meter cannot be read.
Turn on the switch now and the meter reading should be less than 1 ohm.
If not, the switch is faulty and should be replaced.
Another simple test is to rotate the Meter dial to a continuous position.
This means a continuous circuit.
The symbol for the continuity of the surface of the instrument is a wedge that represents a noise wave radiating outward from a point.
Connect the meter through the switch contacts and flip the switch up and down.
If the meter beeps and the switch is in On position, the switch is fine.
If the meter does not beep when the switch is turned on, the switch is broken.
The intelligence to test the extension cord is to use the meter to occasionally test the old extension cord because the damaged wire will shock you or cause a fire.
First unplug the extension cord from the wall and rotate the dial of the meter to the Ohm setting.
To test the grounding of the wire, push the red probe into the small hole at the female end of the wire.
Then touch the Black probe to the circle (ground)
Long protruding from the male end.
The continuous circuit measured from both ends will have resistance.
8 ohms even less.
Now touch the red probe to each flat pointed end of the male end to make sure OL reading.
When analyzing the wire in this way, there should be an open circuit;
There should be no contact between the wire connecting the ground pin and the other two wires inside the wire.
Next, insert the red probe into short (hot)
Female end slot in the wire.
Touch the Black probe to the narrow flat prong on the male end.
The electrical continuity through the wire will have resistance. 8 ohms or less.
Then touch the Black probe to the wide flat prong and then the round prong, the meter should show no continuity and O. L.
Read in these two positions.
Finally, push the red probe to a longer period of time (neutral)
Female end slot in the wire.
Take the Black probe and touch the wide and flat socket.
This continuity creates resistance. 8 ohms or less.
Touch the Black probe to the narrow prong and then touch the round prong to get the O. L. reading.
Run the voltage test after confirming that the wire is not short-circuited.
Plug the wire into the power outlet and rotate the dial of the meter to v ac.
Insert the Black probe into the circular hole at the parent end of the power cord and push the red probe into the narrow slot.
You should get a reading close to 120 volts.
Move the red detector now for a longer period of time (neutral)
Confirm the location of the read. 1 millivolts (
The ground and neutral lines of the socket and the voltage between the ground and neutral lines of the power cord are negligible).
Leave the red probe in a longer slot and move the black probe into a shorter slot to get a voltage reading of about 120 volts, confirming that the extension cord is in good condition.
Apart from all the amazing electricity
Most modern multi-meters can also perform temperature readings.
Simply rotate the meter\'s dial to temperature mode and press the select button to switch between Fahrenheit and Celsius.
Insert the thermocouple into the meter to read the air temperature, or insert the temperature probe to get the temperature reading of the liquid, gel, or track the surface temperature of the gas dryer.
You can observe the temperature cycle of the device without touching the device by hand.
David Shapiro is an electrician in the suburbs of Washington and one of the smartest people we know.
He attended various electrical coding boards and wrote a book about the electrical system of the old residence.
It is considered the final work on this topic.
He is Shapiro\'s eight key suggestions for safe use of the meter, forming the habit of putting fingers on plastic and rubber parts of the meter to avoid contact with a vibrant metal surface.
Wear safety glasses when conducting electrical tests, especially to protect yourself in the event of an electrical flash.
Red to black: if you confuse which probe goes into which Jack, the meter will work properly, but develop the habit of inserting red into red, black to black, as a means of training yourself to associate these colors with polarity and their symbols (the + and -
Signs and colors attached to electrical terminals and wires).
Amateurs should always work on the dead system.
If it turns out that the component is real-time (
Electricity, electrician)
, You may accidentally short circuit between the wall of the metal box and the electrical equipment you are testing.
This may surprise you.
It may also bring you severe electric shock, burn or burn out electrical components.
If it is not damaged before, it will be damaged now.
In the worst case, an electric shock can kill you.
Yes, it is a good idea to test the continuity and impedance of the extension cord, but check your wire regularly visually and check the cut, worn or crushed areas. Know your instrument.
Know what the symbols on its surface mean, and when they appear on the screen, be clear about what you\'re looking.
For example, some meters may read 99999. 99 Not O. L.
The place to start using the meter is its owner\'s manual.
Usually 1 m will not be destroyed when reading is stopped (
Assuming a good battery).
You might have blown the fuse.
Read the manual on how to replace the fuse (
Normally it is located behind a small hatch with small screws attached to it).
Replace the fuse with a fuse of the same size, connect the panel and proceed.
Temperature: When electrical components such as switches, wires and sockets are heated, it is usually indicated that there is a problem.
\"I always tell the customer that if it is warmer than the baby bottle, please pay attention.
\"This is not the time or place for amateur repair measures.
Turn off the power of the circuit and call the electrician.
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