Contents
Today we will talk about multimeters, what they are for, what measurements they make and how to choose the right device.
Progress does not stand still
Anyone who is at least a little familiar with electrics and radio electronics, no matter what – electrical networks at home, radio electronics of household parts or on-board networks of a car, know that it is very difficult to determine the location of a malfunction to eliminate it without instrumentation.
Previously, to measure each parameter, a separate device was required – a voltmeter, ammeter, ohmmeter, which was not very convenient and control measurements took enough time.
And this is only for measuring the main parameters, and for carrying out other measurements, additional instruments and devices were required.
Now, a whole set of instrumentation, each of which measured only a certain parameter, has been replaced by one device that can replace them all – a multimeter.
In addition to the ability to measure the main parameters of an electrical network – voltage, current, resistance and frequency, multimeters allow you to perform a whole range of measurement and control work, since their functionality is very wide.
Of course, the functionality of a multimeter depends on its internal structure, but still, most of them can additionally measure the capacitance of capacitors, inductance of coils, the performance of diodes and transistors, which is important for radio electronics engineers, check noise and illumination, and identify damage to wiring and connections.
Read on the topic – how to check a transistor with a multimeter.
So a multimeter is a universal thing and will be useful to almost everyone who has even a little experience with electrical circuits. But not all multimeters are the same and the selection of this device should be taken seriously.
Types of multimeters
First you need to decide on the type of this device, and there are two of them – analog and electronic.
In an analog multimeter, all the data that is measured is shown by an arrow on the scale.
The scale itself has different graduations, and each of them corresponds to a certain parameter.
The main disadvantage of this type of multimeter is the inaccuracy of readings.
In even a very sensitive device, when measuring, the arrow will have certain fluctuations that will distort the readings.
Of course, if precise measurements are not required and only the overall value of the parameter is checked, then such a multimeter will do. But, in general, analog multimeters have practically “outlived” their own and are now rare.
Analog multimeters from the market “forced out” electronic ones. All measured data are displayed on a digital display, which is much more convenient.
But there are transitional models with an analog and digital display.
After all, in analog, it was still necessary to adapt to the correct calculation of the indications of the arrow on a graduated scale.
In digital multimeters, all this is not required – the measured indicator is displayed in the form of numbers, and large ones, which is much easier to understand.
See also:
Additional Functionality
All multimeters are equipped with a basic set of functions, but there are also additional ones. Therefore, when choosing, you should pay attention to them.
For example, if this device will be used in a domestic environment – checking voltage, current strength, etc. in the house or on-board network of a car, then a multimeter with a basic set of functions will be quite enough.
It will cost less, and its control and measurement capabilities will be enough.
If you need such a device for industrial use or in radio electronics, then it is better to purchase a multimeter with advanced functionality.
For example, the device can additionally create a test signal, test semiconductor devices, record measured values, and automatically determine measurement limits.
Also, additional functions include the capabilities of the device that make it easier to work with it – a sleep timer, display brightness adjustment, a graphical representation of the waveform.
Key features to consider
When choosing a multimeter, its characteristics are important, and there are several of them.
Error
No multimeter will show absolutely accurate measurements, there will always be an error, but it may differ.
The error of these devices varies from 0,025 to 3%. When choosing a multimeter, you should pay attention to this characteristic.
If it is purchased for domestic use, then it can be taken with an error of 3%, this will not particularly affect the measurements.
But for working with radio electronics, it is better to buy a device with the smallest possible error.
Measuring range
This characteristic indicates the minimum and maximum value of the parameter that it can measure.
Usually, for all the main parameters, the measurement range is indicated separately for each.
The choice for this characteristic depends on the scope of the device.
For domestic conditions, a multimeter with a small range will be enough, the main thing is that it is suitable for basic measurements.
For industrial use, it is better to purchase a multimeter with a wide range for each parameter.
Display digits
This characteristic indicates how accurately the device can display readings on the display.
The reading capacity of multimeters can be different. So, a conventional household multimeter has a 2,5-digit display, which is able to show values with an accuracy of up to hundredths after a decimal point.
But the 3,5-digit display is already able to display the value with an accuracy of thousandths after the decimal point.
But it is worth noting that the accuracy depends on the error, therefore, with a large error, the thousandth value of a 3,5-digit display will not have much reliability.
Number of displays
This characteristic is more suitable for those who purchase the device for use in electronics or industrial applications.
For domestic conditions, a conventional multimeter with one display is quite enough.
But the presence of two displays will be appreciated by those who, due to the peculiarities of the profession, have to make a large number of various measurements.
Multimeter Power
Most multimeters use conventional batteries as a power source.
Such a power supply is quite sufficient for household measurements, but for industrial measurements this may not be enough.
Battery-powered multimeters are manufactured for this use.
Samples of multimeters and their characteristics.
AKIP-GDM354A.
Multimeter FLUKE-111.
What to look for when choosing
The chips that are used in this device are usually very reliable, so the country of origin is not that important. This is with regard to the internal filling of the device.
See also:
But the appearance is worth evaluating. The first thing to check is the overall build quality. There should be no loose parts, the body halves should be connected securely, without any gaps.
Cases can also be of several types, which is taken into account when choosing.
For domestic conditions, the device in a conventional plastic case will also go.
For those who will use it in harsh conditions, multimeters are offered in a shockproof sealed case that does not allow moisture and dust to enter.
You should also look at the switches. Switches made of poor quality material will quickly become loose, and it will be difficult to switch to change the measurement parameters.
The inputs on the instrument panel also need to be checked for safety. They must have plastic protrusions around the circumference, which will cover the contact point of the output with the probe plug, excluding the possibility of a person touching the contact.
When choosing, you should also evaluate the ergonomics of the multimeter, it should lie well in your hand. This will ensure the convenience of using the device, which will affect the accuracy of the measurements.
The quality of the probes of the device should also not be forgotten. The probe plugs must fit snugly into the outputs of the multimeter.
The wires must have a good section, this is especially important when measuring parameters with large values. The protective sheath of the wires must be undamaged.
The ends of the probe electrodes must be well pointed, which will allow you to connect the device for measurements even at small points of contact in the circuit.
Finally, you should request a product quality certificate. The absence of it will indicate the handicraft production of the device, there will be little benefit from it, since it will either quickly fail, or its readings will be far from accurate.
This is all you need to know when choosing such a rather important and necessary device as a multimeter.