DIGITAL MULTIMETER PDF

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Digital Multimeter. TECHNICAL SPECIFICATIONS. Variable. Range. Resolution Accuracy. DCV. 1, V 1 µV. ±0, % +5 dgt. ACV. 1, V 1 µV. ± % + Page 1. Digital Multimeter. Instruction Manual. Page 2. 3. 2. TABLE OF CONTENTS page. A. INTRODUCTION. 1. Congratulations 2. [1] SAFETY PRECAUTIONS. This instruction manual explains how to use your new digital multimeter PS8a safely, Before use, please read this manual.


Digital Multimeter Pdf

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To better understand digital multimeters, it's helpful to become clear on the basics of When making measurements with a digital multimeter, it is important to. The Amprobe 5XP-A digital multimeter provides superior features and accuracy in a smaller form factor. The 5XP-A has unique features such as VolTect™. Digital Multimeter. Model MN Page 2. MNen-GB_v 04/ 2. Introduction. Congratulations on your download of the Extech MN42 MultiMeter. The MN

So, you should select a range with the selection knob that can read the 1. So you should select 2V in the case of this multimeter. What happens if you switch the red and the black probe? Nothing dangerous will happen. This example circuit lights up an LED. TIP: two components in parallel share voltage, so you should connect the multimeter probes in parallel with the component you want to measure the voltage.

To measure the voltage drop across the resistor: You just have to place the red probe in one lead of the resistor and the black probe on the other lead of the resistor. The red probe should be connected to the part that the current is coming from.

Measuring Current To measure current you need to bear in mind that components in series share a current. So, you need to connect your multimeter in series with your circuit. The multimeter acts as if it was a wire in your circuit. In the example below, the same circuit of the previous example is used.

The multimeter is part of the circuit.

How to Use a Multimeter to Measure Voltage, Current and Resistance

Measuring Resistance Plug the red probe into the right port and turn the selection knob to the resistance section. Then, connect the probes to the resistor leads. While a digital display can easily be extended in resolution , the extra digits are of no value if not accompanied by care in the design and calibration of the analog portions of the multimeter.

Meaningful i. However, even if its resolution exceeds the accuracy , a meter can be useful for comparing measurements. Specifying "display counts" is another way to specify the resolution. Display counts give the largest number, or the largest number plus one to include the display of all zeros the multimeter's display can show, ignoring the decimal separator.

Often the display count is just called the 'count' in multimeter specifications. One reason for this is that analog meters are more sensitive to changes in the circuit that is being measured. A digital multimeter samples the quantity being measured over time, and then displays it. Analog multimeters continuously read the test value. If there are slight changes in readings, the needle of an analog multimeter will track them, while digital multimeters may miss them, or be difficult to read.

This continuous tracking feature becomes important when testing capacitors or coils, for example.

A properly functioning capacitor should allow current to flow when voltage is applied, then the current slowly decreases to zero and this "signature" is easy to see on an analog multimeter but not on a digital multimeter. This is similar when testing a coil, except the current starts low and increases.

Resistance measurements on an analog meter, in particular, can be of low precision due to the typical resistance measurement circuit which compresses the scale heavily at the higher resistance values.

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Inexpensive analog meters may have only a single resistance scale, seriously restricting the range of precise measurements. Typically, an analog meter will have a panel adjustment to set the zero-ohms calibration of the meter, to compensate for the varying voltage of the meter battery, and the resistance of the meter's test leads. Accuracy[ edit ] Digital multimeters generally take measurements with accuracy superior to their analog counterparts.

Laboratory grade instruments can have accuracies of a few parts per million.

Digital meters usually specify accuracy as a percentage of reading plus a percentage of full-scale value, sometimes expressed in counts rather than percentage terms. Quoted accuracy is specified as being that of the lower millivolt mV DC range, and is known as the "basic DC volts accuracy" figure.

Higher DC voltage ranges, current, resistance, AC and other ranges will usually have a lower accuracy than the basic DC volts figure. AC measurements only meet specified accuracy within a specified range of frequencies. Manufacturers can provide calibration services so that new meters may be downloadd with a certificate of calibration indicating the meter has been adjusted to standards traceable to, for example, the US National Institute of Standards and Technology NIST , or other national standards organization.

Test equipment tends to drift out of calibration over time, and the specified accuracy cannot be relied upon indefinitely. For more expensive equipment, manufacturers and third parties provide calibration services so that older equipment may be recalibrated and recertified. The cost of such services is disproportionate for inexpensive equipment; however extreme accuracy is not required for most routine testing. Multimeters used for critical measurements may be part of a metrology program to assure calibration.

A multimeter can be assumed to be "average responding" to AC waveforms unless stated as being a "true RMS" type. An average responding multimeter will only meet its specified accuracy on AC volts and amps for purely sinusoidal waveforms. A True RMS responding multimeter on the other hand will meet its specified accuracy on AC volts and current with any waveform type up to a specified crest factor ; RMS performance is sometimes claimed for meters which report accurate RMS readings only at certain frequencies usually low and with certain waveforms essentially always sine waves.

A meter's AC voltage and current accuracy may have different specifications at different frequencies. Sensitivity and input impedance[ edit ] When used for measuring voltage, the input impedance of the multimeter must be very high compared to the impedance of the circuit being measured; otherwise circuit operation may be changed, and the reading will also be inaccurate.

Meters with electronic amplifiers all digital multimeters and some analog meters have a fixed input impedance that is high enough not to disturb most circuits. This is often either one or ten megohms ; the standardization of the input resistance allows the use of external high-resistance probes which form a voltage divider with the input resistance to extend voltage range up to tens of thousands of volts.

The impedance of the meter varies depending on the basic sensitivity of the meter movement and the range which is selected.

How to Use a Multimeter – Beginner’s Guide

On every range, at full-scale voltage of the range, the full current required to deflect the meter movement is taken from the circuit under test. Lower sensitivity meter movements are acceptable for testing in circuits where source impedances are low compared to the meter impedance, for example, power circuits ; these meters are more rugged mechanically. Some measurements in signal circuits require higher sensitivity movements so as not to load the circuit under test with the meter impedance.

Multimeters designed for mains "electrical" use instead of general electronics engineering use will typically forego the microamps current ranges. Measurement of low resistance requires lead resistance measured by touching the test probes together to be subtracted for best accuracy. This can be done with the "delta", "zero", or "null" feature of many digital multimeters. Contact pressure to the device under test and cleanliness of the surfaces can affect measurements of very low resistances.

Some meters offer a four wire test where two probes supply the source voltage and the others take measurement. Using a very high impedance allows for very low voltage drop in the probes and resistance of the source probes is ignored resulting in very accurate results. Burden voltage[ edit ] Every inline series-connected ammeter, including a multimeter in a current range, has a certain resistance.

Most multimeters inherently measure voltage, and pass a current to be measured through a shunt resistance , measuring the voltage developed across it. The voltage drop is known as the burden voltage, specified in volts per ampere. The value can change depending on the range the meter sets, since different ranges usually use different shunt resistors. To check for its effect on accuracy and on external circuit operation the meter can be switched to different ranges; the current reading should be the same and circuit operation should not be affected if burden voltage is not a problem.

If this voltage is significant it can be reduced also reducing the inherent accuracy and precision of the measurement by using a higher current range. Alternating current sensing[ edit ] Since the basic indicator system in either an analog or digital meter responds to DC only, a multimeter includes an AC to DC conversion circuit for making alternating current measurements. Basic meters utilize a rectifier circuit to measure the average or peak absolute value of the voltage, but are calibrated to show the calculated root mean square RMS value for a sinusoidal waveform ; this will give correct readings for alternating current as used in power distribution.

User guides for some such meters give correction factors for some simple non- sinusoidal waveforms , to allow the correct root mean square RMS equivalent value to be calculated. More expensive multimeters include an AC to DC converter that measures the true RMS value of the waveform within certain limits; the user manual for the meter may indicate the limits of the crest factor and frequency for which the meter calibration is valid.

RMS sensing is necessary for measurements on non-sinusoidal periodic waveforms, such as found in audio signals and variable-frequency drives. Modern multimeters are often digital due to their accuracy, durability and extra features. In a digital multimeter the signal under test is converted to a voltage and an amplifier with electronically controlled gain preconditions the signal. A digital multimeter displays the quantity measured as a number, which eliminates parallax errors.

Modern digital multimeters may have an embedded computer , which provides a wealth of convenience features. Measurement enhancements available include: Auto-ranging, which selects the correct range for the quantity under test so that the most significant digits are shown.

For example, a four-digit multimeter would automatically select an appropriate range to display Remember when you are making a measurement with a meter to set the range first before you connect the probes to the voltage under test. In other projects Wikimedia Commons.

AC voltage like what comes out of the wall can be dangerous, so we rarely need to use the AC voltage setting the V with a wavy line next to it. Quoted accuracy is specified as being that of the lower millivolt mV DC range, and is known as the "basic DC volts accuracy" figure.

Turn the dial of the meter to the diode test setting, which is indicated by a triangle with a bar at the end see the photo showing symbols used on meters above. Safety[ edit ] An example of input protection on the CAT-IV rated Fluke 28 Series II Multimeter Most multimeters include a fuse , or two fuses, which will sometimes prevent damage to the multimeter from a current overload on the highest current range.