How to use a voltage tester correctly? Instruction manual

Tester - how to use

Often in everyday life you need to measure the voltage level in the network, the current consumed by the household appliance or simply determine the polarity of an unknown power source. For these purposes, a tester is usually used - a universal device for measuring numerical values ​​of direct and alternating voltage, current strength and resistance.

Modern testers are usually called multimeters, and they have advanced functionality. Thanks to them, you can determine the polarity of the diode, measure the capacitance of the capacitor, and the most "advanced" models equipped with an additional remote sensor allow you to measure the temperature of the object.

The person who first picked up this simple device, sometimes embraces the flutter and the question arises before him - "... but how to use this thing?" However, there is nothing complicated if you know:

• principal device of the tester;
• rules for choosing the type of measurement and setting its limits;
• basic safety precautions for handling this appliance.

Types and designs of modern multimeters

Today for domestic use I release two types of testers:

• analogue, at which the level of the measured parameters are read on a scale with an arrow;
• digital, on the liquid crystal or LED indicator (display) which displays the digital value of the measured parameter.

To connect to the measurement object, the multimeter is equipped with probes, the pointed ends of which are connected to the points of voltage, capacitance, current and other parameters. To connect with the device, the probes are equipped with flexible multi-colored wires with plugs. In this case, the black wire usually corresponds to the negative conductor, and red - to the positive. The corresponding sockets on the front panel are marked with the same color.

However, multi-colored coloring does not carry any functional load, but is performed only for the convenience of the user. The latter are connected to the jacks of the device. For ease of use, the tips of the probes can wear clips - “crocodiles”.

Today, digital instruments are becoming increasingly popular, while analogue (analogue) instruments are gradually disappearing. The undoubted advantage of digital models is that most of them do not require polarity when connecting probes.

If you measure the battery voltage with a digital device and at the same time confuse the plus with the minus, you can bend the indicator arrow. The digital tester will display on the indicator the actual voltage value, only with a minus sign.

A simple, household Chinese tester that allows you to measure:

• AC and DC voltage in the range 0... 1000.0 volts;
• current in AC and DC circuits;
• active resistance.

can be purchased for 200.0... 250.0 rubles.

A tester that additionally allows you to measure the basic parameters of transistors and diodes, as well as determine the temperature using a thermocouple or thermistor, will cost no more than 500.0 rubles.

If earlier the measurement range (limit) was measured by “plugging” the plug into various sockets on the front panel device, today the vast majority of devices has a batch switch, the rotation of the handle of which sets the desired limit.

Before using the tester-multimeter, you need to study the designation of the sockets located on the front panel of the device to which the plugs are connected for measuring various types of electrical parameters.

On simple devices designed to measure voltage, current and resistance, there are several sockets, designated by the acronym "ACV", "DCA" and some other letters (depending on model and functionality appliance). In these designations, the letters mean:

• “DC” - socket for measuring DC parameters;
• “AC” - socket for alternating current;
• "V" - voltage ("V" - "V" - volts);
• “A” - current (“A”) - amperes).

In some models, a three-character designation may not be available and the sockets are indicated more clearly: “V ~”, “V ±”, “A” and some others.

Electrical measurement

When measuring the values ​​of parameters of interest, you need to know:

• voltage is measured when the tester probes are connected in parallel to the source (electrical outlet, battery terminals);
• current is measured at break of an electric circuit;
• resistance, capacitance, inductance - when connecting the probes to the terminals of the object, the parameters of which must be measured.

Moreover, the accuracy of measurements for household testers is usually 1.0%... 3.0%, which is caused by circuitry and used electronic parts. Consider the procedure for various measurements.

DC and AC voltage

Direct and alternating voltage is measured as follows.

We connect the plug to the sockets on the front panel:

• black wire to the negative (mass) jack indicated by the icon, “COM” or “_┴»;
• red to the “DCV” jack for measuring direct voltage or to “ACV” for alternating voltage;
• by turning the knob select the desired range;
• connect the probes to the contacts (terminals, sockets) of the measured source;
• read the voltage value from the display.

The accuracy of measuring AC voltage is affected by the resistance of the diodes, which convert it to constant. However, usually the measurement accuracy is quite sufficient for domestic needs.

When determining the magnitude of the current

When determining the current value of the plug, they are connected to the device in the same way, and the probes are connected to an open circuit, for example, between a light bulb and a battery, or electric stove and a power outlet. In this case, it is important to determine the measurement range, because an increased level of current flowing through the device can lead to its breakdown.

Therefore, in some models, for measuring large values ​​of AC and DC current, there are separate sockets or values ​​on the switch scale, designated as “DC10A” or “AC20A”.

Resistance measurement

The measurement of the resistance of the resistor, the filament of a lamp or an electric stove should be carried out on a de-energized object. To measure the value, perform the following steps:

• switch the device switch to the range indicated by "Ω";
• connect the probes to the ends of the resistor or the contacts of the light bulb;
• read the measurement value from the display.

To increase the reliability of the result, the measurement of a specific sample should be carried out at different positions of the range switch. Similarly, you can determine a wire break. If the device shows a zero value, then the wire is working. If the readings jump or are not determined, a wire break is possible.

Diode diode

The diode dialing is also carried out in the resistance measurement mode. Red and black probes are alternately connected to the diode terminals. In one case, the resistance will be quite large, in the second it is at the level of hundreds of ohms - several kilo-ohms.

Already this procedure allows you to determine the absence or presence of breakdown "pn" - transition. If the tester, when connected to the diode, shows the value in ohms - kilo-ohms, then the red probe is connected to the anode of the electronic device.

Additional functions

Modern models of household multimeters often allow you to check the parameters of bipolar transistors, as well as determine the inductance of the coils and the capacitance of the capacitors. There is a special range on the switch scale for this.

Transistor test

Checking transistors is a rather specific procedure and is only required for persons involved in the repair of electronic equipment. To determine the operability of a bipolar triode, a procedure similar to the diode sounding is used. The probes are alternately connected to the terminals “base-emitter” and “base-collector”.

If the readings of the device correspond to the readings as when checking the "pn" - transition of the diode, the transistor can be considered serviceable. However, the gain cannot be determined in this way.

Determination of capacitance and inductance

The capacitance and inductance are determined when the multimeter is switched to the range “L” (inductance) and kb “C” (capacitance). The plugs of the device are connected similarly to the measurement of resistance. When determining the capacitance of electrolytic capacitors, the polarity of the connection must be observed.

When measuring resistance, capacitance and inductance, as well as when working with diodes and transistors, you should use crocodile clips. If the probes are pressed to the conclusions with your fingers, then the resistance of the human body can introduce a rather large error in the measurement result.

Using a tester with a car enthusiast

Some motorists mistakenly believe that the tester is an indispensable assistant in the repair and diagnostics of the car's electrical equipment. However, this is not the case. Even the true voltage value at the battery terminals can only be determined with a load plug.

You can “ring” the wiring with a multimeter and find the area of ​​wire breakage, check the fuse blowing, but to use a household appliance for more complex work with the electronics of a modern car is by no means follows. There are special automotive testers for this.

Tester Care

Caring for a household multimeter is not difficult and is similar to caring for a wall electronic clock. The only thing required for him is to prevent mechanical damage and periodically change the power source.

If the tester fails, then most users prefer to throw out the multimeter and buy a new one. Repairing these products may cost more than the cost of a new tester.