A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability to measure voltage, current and resistance.
Two Kinds of Multitester
- DIGITAL MULTITESTER
A digital multimeter is a tool that can measure amps, volts, and ohms. It is different from an analog meter,which has a needle and a gauge, in that it has a digital light-emitting diode (LED) display. Digital multimeters are typically more accurate than their old analog counterparts. A digital multimeter can also have other functions; obviously, the more expensive meters will have more features, but all of them measure the three basic currents.
- ANALOG MULTITESTER
An analog multimeter (AMM) is a multi-purpose electronic testing device. A unit will be capable of measuring voltage, current, and resistance and often has the functionality to test for frequency and signal power as well. The display of an analog multimeter usually relies on a microammeter to move a physical pointer over a calibrated scale. The device may also be referred to as a multitester or a Volt-Ohm meter.
Parts of an Analog Multitester
- POINTER- The needle-shape rod that moves over the scale of a meter . It is mechanically connected to the moving coil. It indicates the measured values on the multimeter.
- RANGE SELECTOR KNOB/selector switch- makes it possible to select different function and range of the meter.
- ADJUSTMENT SCREW– makes it possible to adjust the pointer to the zero position of the scale.
- SCALE–is a series of marking used for reading the value of quantity. Scale can have different types of scale, for voltage and current readings the scales have mostly linear which mean equal division for resistance .
- TEST PROBE- Positive (red) negative (black) is use to connect the circuit to theelectrical components being tested.
- ZERO-OHM ADJUSTMENT KNOB–is used to zero-in the pointer before measuring resistance
How to use a Multitester
A multimeter is an instrument used to check for AC or DC voltages, resistance and continuity of electrical components, and small amounts of current in circuits. This instrument will let you check to see if there is voltage present on a circuit. By doing so, a multimeter can help you achieve a variety of useful tasks. Start with Step 1 to familiarize yourself with the device, and learn to use different functions to measure ohms, volts, and amps.
Getting Familiar With the Device
Locate the dial of your multimeter.
- The arc-shaped marks on the meter dial face may be different colors that indicate each scale, so they will have different values. These determine the ranges of magnitude.
- A wider mirror-like surface shaped like the scales might also be present. The mirror is used to help reduce what's called "parallax viewing error," by lining up the pointer with its reflection before reading the value the pointer is indicating. In the image, it appears as a wide gray strip between the red and black scales.
Many newer multimeters have digital readouts, rather than the analog scale. The function is basically the same, you'll just get a numerical readout.
Find the selector switch, or knob.
- Some meters have an "Off" position on this selector switch while others have a separate switch to turn the meter off. The meter should be set to "Off" when stored and not in use.
Locate the openings in the case where you'll insert the test leads. Most multimeters have several jacks used for this purpose.
- One is usually labeled "COM" or (-), which stands for for common. This is where the black test lead will be connected. It will be used for nearly every measurement taken.
- The other jack or jacks should be labeled "V" (+) and the Omega symbol (an upside down horseshoe) for Volts and Ohms, respectively.
- The + and - symbols represent the polarity of probes when set for and testing DC volts. If the test leads were installed as suggested, the red lead would be positive as compared to the black test lead. This is nice to know when the circuit under test isn't labeled + or -, as is usually the case.
Many meters have additional jacks that are required for current or high-voltage tests. It is equally important to have the test leads connected to the proper jacks as it is to have the selector switch range and test type (volts, amps, ohms) set. All must be correct. Consult the meter manual if you're unsure which jacks should be used. 
Locate the test leads. There should be two test leads or probes. Generally, one is black and the other red. These are used to connect to whatever device you're planning on testing and measuring.
Find the battery and fuse compartment. This is usually found on the back, but is also sometimes on the side of some models. This holds the fuse (and possibly a spare), and the battery that supplies power to the meter for resistance tests.
- The meter may have more than one battery and they may be of different sizes. A fuse is provided to help protect the meter movement. Likewise, there is often more than one fuse. A good fuse is required for the meter to function, and fully charged batteries will be required for resistance/continuity tests.
Why do we need to stop measuring before we switch or change a range?
ReplyDeleteBecause we need to calibrate first the pointer to get an accurate result
Deletecan we measure the voltage of grounded outlet using multimeter '?
ReplyDeletecan we measure the voltage of grounded outlet using multimeter '?
ReplyDeletewhat do you mean by "grounded outlet"? Are you referring to the outlet with three prong?
DeleteIf yes, you can measure rather test the voltage using multester. Here is the step:
Testing for Ground
If you get a positive voltage reading when the two probes are in the two slots, remove the black probe from the larger slot and slide it into the U-shaped ground hole. You will know that the receptacle is properly grounded if your voltage reading is the same now as it was when the black probe was in the larger slot.
If the tester does not read voltage when you have the red probe in the short slot and the black probe in the ground slot, then keep the black probe in place and move the red probe over to the larger one. If you get a positive voltage reading with the probes in this position, then this is a case of "reverse polarity," or in other words, the receptacle was wired in reverse (with the hot wires connected to the neutral side of the receptacle and the neutral wires connected to the hot side of the receptacle) and it should be corrected.
If the tester reads positive voltage when the two probes are in the top two slots but it does not read voltage through either slot when you place the probe in the ground hole, then the receptacle is not grounded. You should check all of the remaining receptacles in the vicinity to find out whether this is an isolated incident or there is a larger concern. In either case, a non-grounded receptacle should be repaired as soon as possible to ensure it is safe for use.
Does the analog tester have any functionality that the digital tester doesn't have?
ReplyDeleteAnalog and Digital multitester is the same the only difference is that digital tester display its reading in a LCD screen while in analog tester you have to read the scale to be able to know the actual reading but all in all their functionality is the same
DeleteMa'am what is the advantage of digital multitester in analog multitester?
ReplyDeleteSince analog and digital multimeter have the same functionality the only thing that i think digital multimeter strenght is you can easily get the reading.
ReplyDeleteHi Mam Maureen! How am I going to troubleshoot a multimeter?
ReplyDeleteMultimeter Troubleshooting and Repair
ReplyDeleteYour multimeter should last for a number of years with reasonable care, but there may come a time when you multimeter malfunctions and you’ll have to decide whether to repair it or buy a new one. Before going out and looking for a new multimeter you should use the following techniques to troubleshoot and repair you multimeter.
The first step is to check the battery. Try to power on your multimeter. If the multimeter doesn’t turn on or the display is dim you may have a weak or dead battery. Simply replace the battery and you should be good to go.
If your multimeter powers up but you aren’t getting accurate measurements you may have faulty test leads. Set your multimeter to read resistance and touch the test probe leads together. It should read zero ohms. If you have resistance ratings of over one ohm or the reading is erratic, you should be able to fix the problem by replacing the probe leads.
If you still haven’t been able to address the issue the next step is to disassemble your multimeter. Use a small screwdriver to remove the screws holding the case together.
After you’ve opened the multimeter locate the fuse and remove it. If it’s a clear glass fuse inspect the inside to see if the thin wire within is burned out. If it’s blown, replace it. If it’s a ceramic fuse you’ll have to check its resistance with another multimeter and, if there is no resistance, you’ll need to replace it. (Consult your multimeter’s manual to find out which fuse you need.)
Look for wires and other connections that may be corroded or broken. If you do find a damaged connection desolder it with a soldering iron and wick and resolder it.
Check for loose parts or screws inside the multimeter’s case and fix them in the appropriate way.
Reassemble your multimeter, set it to measure resistance, and touch the probe leads together. It should read well under one ohm. If the multimeter is still malfunctioning, it may be time to replace it.
Ma'am Maureen what is more convenient to use analog or digital multitester and why?
ReplyDeleteMa'am what will happen, if i accidentally swap the test leads??
ReplyDeleteBoth digital and analog multimeters function as great tools for measuring electrical current, voltage and resistance, but for me it is convenient if we use anlog multitester because it is more accurate.
ReplyDeleteMa'am, what will happen if the i am testing for ACV and the selector knob is in Resistance range?
ReplyDeletethere's a tendency that your multitester will be ruin.
ReplyDeleteWhy does my multimeter not go to zero in the ac volts mode?
ReplyDeletewhat kind of multitester are you using?
ReplyDeleteFor a digital multimeter, it's normal that the voltage readings change while the probes are not hooked up to anything. And if you are using an analog digital Multitester sometimes brand does matter. If you are using If it is a true-rms ac multimeter, such as the 17X or 8X, it will not zero and should not be zeroed. Most of these true-rms type multimeters have a minimum ac voltage and current level specification for both the ac volts and ac current modes, typically specified from 3% to 5% of range. When a signal is applied above the specified minimum level, the meter will meet its accuracy specifications. You will find this specification in the specification section in the rear of the user manual.
maam para san po ung output na saksakan sa multi tester ?
ReplyDeletePwede mo rin syang gamitin para saksakan ng probes.
ReplyDeleteYou did an excellent job on this post!
ReplyDeleteIn this article, you will learn how to make a rechargeable digital multi-meter from PVC pipe sheets at home. We will use PVC pipes sheets to make a multi-meter box. You can easily make a digital multi-meter at home in simple steps.
When comparing all of the multimeters on the market, it is safe to say that Fluke products are among the best that an electrician can use on a daily basis.
ReplyDeleteI've been using a basic multimeter for years, but after reading your post on true RMS multimeters, I'm convinced that I need to upgrade! Your article provided a clear explanation of what makes these meters so much more accurate and versatile. Thanks for the great info! Have you used fluke true rms multimeter 179
ReplyDeleteWith rugged construction and robust components, Fluke meters can withstand the rigors of daily use in challenging environments. This durability not only protects your investment but also ensures that your multimeter will continue to perform reliably for years to come.
ReplyDelete