Multimeter – additional functions
Multimeter – additional functionsDate of publication: 02-07-2025 Update date: 10-04-2026 🕒 12 min read
Piotr Górecki – electronics enthusiast. Currently, he publishes his own magazine "Understanding Electronics." Previously, for many years, he was the Editor-in-Chief of a popular Polish magazine (Electronics for Everyone). He is also the author of hundreds of articles and educational projects. Until 1993, he worked in the telecommunications industry.
In the first article of this series, elementary news about multimeters was given and basic measurements were described: voltage, current i resistance. Now, in the second, we will cover the Others functions of multimeters. In the third we will answer some questions and discuss doubts about multimeters.
This three-part article is intended for complete beginners. In the first article of the series, we discussed basic measurements: voltage, resistance, and (current) intensity. Now we will discuss other, more and less practically useful functions of multimeters.
Diode Measurement
Practically all multimeters have the ability to measure the forward voltage of a diode.
Overall, this is a moderately useful function in practice. It can be used to check the polarity of various diodes – when connected in reverse, the instrument will show an overrange. For an electronics enthusiast, this function allows distinguishing ordinary silicon diodes from Schottky diodes.
Unfortunately, in most multimeters, this function is not useful for checking LED diodes. However, there are exceptions – a few multimeters allow identifying the color of LED diodes.
In any case, it is worth knowing that when this function is selected, the multimeter works similarly to an ohmmeter, but instead of resistance, it shows the voltage present on the measured element.
Photo 1 shows examples. Tiny 1N4148 diode has a conduction voltage of 606mV, the popular 1N4007 - voltage of 603mV, and the sizable, 15-ampere Schottky diodes only 171mV, i.e 0,171V. However, this is the case only at very low current measurement. During normal operation, the voltage drops across the Diodes will be greater.
Photo 1
Only a few multimeters can measure the conduction voltage of LEDs in this way. An example of an attempt to measure a blue LEDs can be found in photograph 2. As you can see, with the task coped BM785, and the much more expensive OWON B41T although it illuminated the diode, but did not show the voltage present on it. By the way: it is well known, that the operating voltage of white and blue Diodes is greater than 3V, meanwhile, the conduction voltage shown here is only 2,578V. With such a voltage and small current, the Diodes already shine quite brightly, but of course, during normal operation, when the current of the diode would be much larger, the conduction voltage would be higher.
Photo 2
Bipolar Transistor Measurement
Many cheap multimeters have a socket for checking the gain of NPN and PNP bipolar transistors – photo 3. The display shows the current gain value at very low currents, which will certainly be significantly different at higher currents.
Photo 3
This function might have been useful once – nowadays, for several reasons, it is rather a worthless gadget. Today, a measurement of MOSFET transistors would be much more needed, but multimeters do not offer such a function.
Capacitance Measurement
For an electronics enthusiast, the ability to measure capacitance is useful. Photo 4 shows an interesting example of measuring the capacitance of the same 10µF capacitor.
Photo 4
As you can see, indications vary significantly. Multimeters can be used to identify the denominations of capacitors, that do not have markings or to check, whether the capacitor is not damaged. Such meters can also be used to select capacitors with exactly the same capacitance, which is needed in some circuits - then the absolute accuracy is not important, only the repeatability of the measurement.
Multimeters with the ability to measure inductance are even rarer – and rightly so, because measuring inductance is a very complicated issue, and measurement results can be misleading. The only one of my multimeters with such a function, measuring a coil with a nominal value of 100 microhenries, is shown in photo 5.
Photo 5
Temperature Measurement
Some multimeters allow measuring temperature using a so-called K-type thermocouple (photo 6), but the practical usefulness of such a function for a hobbyist is small, due to at least a few degrees of allowable measurement error.
Photo 6
Frequency and Duty Measurement
Theoretically, the frequency measurement function, available in many more expensive multimeters, should be very useful. In practice, it varies. Attempting to check the frequency of the power grid is pointless (photo 7). The frequency in the European power grid is 50Hz with high accuracy – better than the accuracy of meters. The grid frequency can even be used as a standard.
Photo 7
Frequency measurements in digital circuits make sense and usually do not involve problems. However, in analog circuits, including radio circuits, this function often proves to be of little use due to low sensitivity and limited measurement range.
The DUTY function, which allows measuring the duty cycle of a square wave (duty factor), is even less useful – usually, for several reasons, it is better to use an oscilloscope for this.
Other Multimeter Functions
A few multimeters have a built-in square wave generator (photo 8), very rarely a sinusoidal one. A primitive generator in a multimeter is also a very little useful function in practice today.
Photo 8
A few multimeters have additional ranges for measuring popular batteries – examples in photo 9. The measurement is made with the battery loaded with some small current. This is also a very little useful advertising function, intended to increase the attractiveness of the instrument for uninformed people. Frankly speaking, instead of helping, it can be misleading, as the load current during tests should be appropriately selected according to the voltage and size (capacity) of the battery.
Photo 9
In practice, it is usually sufficient to simply measure the battery voltage without load with a voltmeter in the appropriate range (usually 20V for all batteries and accumulators). Only in exceptional cases is it necessary to measure the voltage under load – however, this is a separate topic.
What is the NCV Function?
In newer, more expensive meters, the NCV (Non-Contact Voltage) function has appeared. Such a marked meter has a built-in alternating electric field sensor. It can usually operate in two modes. In the wireless mode, holding the meter in hand, you can non-contact detect the presence of a phase wire of the 230V power grid (marked L), in which voltage occurs, for example, the path of wires in the wall. Photo 10 shows an example – the closer to the wire, the more horizontal lines appear on the display, accompanied by an intermittent sound signal.
Photo 10
In the second mode, as shown in figure 11, using only one wire, you can identify the phase wire under voltage and the neutral (or protective) wire – in this second mode, the instrument replaces the still popular “screwdriver with a neon” – photo 12.
Figure 11
Photo 12
Individual meters with NCV signal the tested state differently with the buzzer sound and display image. Moreover, such electric field sensors can be capricious, so before using the NCV function, you should thoroughly familiarize yourself with the user manual of the meter being used and conduct tests.
Analog Multimeter
In my opinion, there are no rational reasons to buy an analog multimeter today – an example in photo 13. Analog multimeters are generally not only less accurate, they electrically load the measured circuit or system more, but above all, they have a delicate mechanical construction and are easily damaged in field conditions. You can buy one, but rather only for sentimental reasons.
Photo 13
Nevertheless, if an older instrument of this type (example in photo 14) falls into your hands, it is definitely worth keeping.
Photo 14
And a huge rarity is the famous, almost cult Polish analog multimeter V640 (example in photo 15) – in the right hands of a conscious electronics enthusiast, it can prove more useful than a modern digital one.
Photo 15
Another issue is the (pseudo)analog indicator called a bar graph in digital meters – an example of a bar graph in the OWON B41 T+ multimeter can be seen in the earlier photo 2. In not very numerous applications, the bar graph as an equivalent of the pointer is useful for observing current changes in the measured quantity, which is easier than analyzing numbers. Overall, however, its practical usefulness is small.
Multimeter with Oscilloscope
Various multimeters equipped with a simple oscilloscope function are available on the market – an example in photo 16. If someone has money and likes gadgets – let them buy.
Photo 16
Those who approach purchases rationally and economically should separately buy a sensible classic multimeter and a sensible oscilloscope (preferably four-channel). Yes, there are commendable so-called scopemeters, but they are very expensive. However, an inexpensive multimeter with an oscilloscope will likely have compromise, unsatisfactory parameters. This is, however, a debatable topic for a separate article.
Accessories
Most inexpensive multimeters come with only two poor-quality measurement cables – probes with wires in PVC insulation. The insulation is often quite thick, but the copper wires inside are surprisingly thin. And what is important in practice – such cheapest probes usually have blunt tips. An example in photo 17. Many people separately buy much better measurement cables with better tips.
Photo 17
On one hand, safety and insulation quality are important, but for the modern electronics enthusiast, it is important that the probes have thin and sharp tips so that there are no problems with measurements inside densely packed systems. This is another extensive topic that we will return to.
And now just one detail. Namely, an indispensable part of the workshop equipment should be universal small crocodile clips of the "banana 2mm" standard, which can be placed on probes according to photo 18, which brilliantly facilitates some measurements.
Photo 18
And the next article (B042) in this series intended for less advanced readers is titled: Multimeter – Questions and Doubts. ©
Piotr Górecki
Disclaimer:The contents of this article are for informational purposes and do not constitute technical advice or a substitute for appropriate training. When working with electrical and electronic equipment, always observe applicable Health and Safety regulations and follow the manufacturer's recommendations and operating parameters.
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