We do not recommend immediately trying to check the voltage of 220 V. Start with a simple one. For example, suitable battery or battery from the phone. Then try to play with gadget power devices. And later allowed to go to the outlet. There are many difficulties in using a multimeter because not all ranges are written with instructions. Even an experienced master is sometimes unable to understand what is written.
The ranges of multimeters
Verifying the correctness of the connection of the probes becomes an important part of understanding how to use a digital multimeter. This is written in the instructions, read carefully. An indirect confirmation of the correctness of the operations performed will be a bell when the probes touch the range marked with a thick arrow with a cross bar at the end( continuity of the diodes).Sometimes a similar function is marked with a dot with arcs diverging from it( this is the name for the buzzer, bell).To test the multimeter for performance, an additional mode is introduced that requires special instruments. Let's run through only the key options.
We recommend starting with checking the voltage on the battery. It is safe for humans and used tester. The battery will not suffer. But the person will learn on the example of an important thing - the polarity of voltage.
The multimeter has two probes. One red is traditionally a plus. Black wire is considered common, on the front side is designated as COM( common).This land is either the second name is a minus. At the same time there are three or four nests in the tester. The black wire is usually fixed, and the red one moves according to the scale used and the type of work. Mostly concerns just currents and tension, other works are carried out in any state.
We set the range of positive voltages. We find on the front panel the letter V with a straight line, under which there are three points( see figure).We look at the nominal value of the battery, set the range so that the figure is guaranteed inside. Separate figures on the front panel in the section of constant voltages are preceded by the letter m. This means that we are talking about thousandths - millivolts. This increases the accuracy of measurements in cases where we are talking about weak voltages.
The red probe leans against the positive pole of the battery, and the black one towards the negative. The face value appears on the screen with minor deviations. If the polarity is confused, the digit is negative. With a phone battery too easy. On the battery case there are three contacts, and the only one - usually the left one - becomes a voltage source. The other two are land. Voltage is naturally positive.
Proceed further in accordance with the guidelines given above. The battery rating is inscribed on the case. For example, 3.5 V. We put the range on the multimeter to 20 V. It is permissible to check the battery charge indirectly. With the fall of stored energy, the voltage decreases. Therefore, in everyday life they say - the batteries "sat down".
Measurement of resistance
The function is often needed in everyday life when you have to mess around with the ground loop of the apartment. The family of ranges that measure resistance is under the letter of the Greek omega alphabet( see figure).The selected numbers are preceded by the letter k when it comes to kilo omes. The appropriate range is selected for maximum accuracy. For example, at 200 ohms, the tester shows tenths, and at 2000 ohms it no longerThis is rarely required, it is supposed to relate the ranges.
To evaluate what you need, find out how the labeling is made. On the old resistors usually write directly nominal. The letter k designates the prefix kilo, M - mega, G( G) - giga, T - tera. Particularly labeled resistors of small denomination. For example, 1R5 means that the resistor is 1.5 Ohms. You will need to select the smallest range. Recently, reviews have given an example of indirect resistance measurement, whose accuracy is much higher. We will not repeat, go through the site. Find a lot of interesting.
Accuracy is subject to separate labeling. Usually comes after the denomination and denoted by the number in percent. Sometimes tolerances are given in letter codes. For example, L corresponds to 0.01%.Read more in GOST 28883. In addition, it will be possible to get acquainted with the color markings and their purpose. We add that the significant bands on the resistor body are 4–5, and the value of the denomination is more convenient to determine by online calculators. Look, for example, on the site of the Chip & Dip store.
After the battery, it’s time to master a more serious task - alternating voltage. Pre-learn to poke probes in the right place. When working with the industrial standard 220 V is likely to spoil something. For testing, let's try the charger of any phone.
Try to find an old one with open contacts, miniUSB is not something with which it is convenient to work with standard tester probes. Usually for hard-to-reach places, special needles are used, which are bought specially, are absent. When the open connector of the phone adapter is facing the person, the phase is on the left. This is a common step. In the outlet phase must also be on the left. In the indicated place we put the red probe, black on the second terminal( or the case, if there is no second terminal).The tester will show the standard voltage of the adapter. Do not forget to plug it in.
Before testing the AC voltage, you need to set the correct range. For Russian outlets, this is 750 V. In practice, there is 230 V in the houses( for compatibility with European technology), and the 200-volt scale is not enough. Check out our picture for setting the range. The group of alternating voltages is marked with the Latin letter V, further goes tilde ~.
When working in the specified mode, the polarity of the probes does not matter. We recommend using the red wire for the phase to get the right skills. Probes perfectly enter the euro sockets and the usual. The display will show 220-230 V.
The modes of the devices
- The diode continuity mode is also used to test the integrity of the wires. Before starting work, it is recommended to close the probes. A squeak is heard. For testing, take the carrier( extension).It is not necessary to stick into the outlet. Now attach any probe to one pin of the plug, and the second plug into any extension socket( go in two rows).If the squeak is not heard, move the first probe to the second pin. Proper carrying easily tolls. Please note that as the work progresses, the numbers on the display change. The tester shows the line resistance at the same time. This is convenient, but the readings are not very accurate. Therefore, to measure small resistances of wires, it is still recommended to use a special mode from the Ω group. Resistance indications are proposed to be used to assess the performance of the diodes. It is known that in Germany the specified parameter is lower than in silicon. Often, to estimate the parameters you need to know the voltage on the probes. The tester forms a potential for measuring. To solve the problem, a good capacitor of a decent capacity is needed( for example, 100 µF).Lean the test leads according to polarity( if any) for charging. The red wire is a plus. It is convenient to do this in the mode in question for a simple reason: on the screen, the resistance of the capacitor goes through all the stages from zero to infinity. When the digits run out, go into the measurement mode of small constant voltages and estimate the potential. This will be your own auxiliary voltage, formed by the tester. Knowing it, it is clear how the diode corresponds to the declared characteristics. This is a separate topic addressed earlier.
- Modern devices measure the current gain of the transistor. For new people, we inform you that the value depends on the applied voltage and the transmitted current, not every transistor is allowed to be tested with complete success. Powerful elements will require the assembly of special schemes for testing. The mode is called hFE by the first letters of the parameter in English. The letter h denotes the h-parameters( logical).The letter F stands for forward( forward) current gain, and E refers to the type of switching circuit of a transistor with a common emitter( emitter).For testing, look at the jack on the front panel of the multimeter. It is round and vertically divided into two equal halves. Each is intended to assess the performance of one of the types of bipolar transistors: npn and pnp. Field-effect transistors are allowed to check, but already in abnormal modes. You need to clearly understand how the multimeter works, then you can even ring a triac. Each hole in the transistor test jack is labeled: B - for the base;C - for the collector;E - for the emitter. Find out from the documentation the type of transistor purchased and accordingly insert its legs into the holes. Go to hFE mode now, the current transistor gain will appear on the screen.
- The mode of measuring capacitance is based on the evaluation of the constant discharge of a circuit from a capacitor and the internal resistance of the tester. Not every multimeter includes this option, and it seems extremely convenient for amateurs. To properly use the capacity evaluation mode, find out the labeling procedure. Typically, the value of capacitors is represented as pF.Otherwise, the letters are put: m - milli, μ - micro, n - nano, etc. They, respectively, denote negative degrees of the number 10: 3, 6, 9. Picofarades( p) - negative twelfth degree. For example, 33.2 pF is denoted as 33p. To capacitors and resistors are created tolerances nominal. They demonstrate a familiar look and are defined by a similar standard - GOST 28883. After evaluating the value of your own capacitor, select the correct range on the multimeter, and then measure it. Polarity sometimes plays a role. For example, when working with electrolytic capacitors. Try not to confuse red plus and black minus.
We will not dwell on how to measure the current with a multimeter. We add only that the work goes exclusively with constant levels. Violation of the rule in order to test the relay for operability, for example, will lead to the tester's failure. Remember, if the expected current in the measurement circuit is greater than the limit for the scale, the voltage regulator of the power generator must be adjusted properly to correct the mentioned deficiency - if possible.
After some time using the device, the described techniques and regulations will become obvious.