How to use multiple meters and precautions

Instructions for the use of multi-meter: multi-meter is a kind of instrument commonly used in laboratory and life, although its range and accuracy are different, but the use method is exactly the same, the following is an example of the elective 3-1p69 diagram of the people's education version, and the use of multi-meter methods and precautions:

Before use, pay attention to whether the pointer is pointing at the mechanical zero position, if it is not at the zero position, adjust the mechanical zero adjuster to make the finger point to the zero position.

Insert the red and black test sticks separately"+""-"Socket.

Measure the resistance: short the two pen and adjust the ohms.

The zeroer points the pointer at ohmic zero; Separate the meter pen, measure the resistance, adjust the ohmic gear from large to small, and the pointer points to the vicinity of **, and the reading is the most accurate.

Measurement of DC current: screw the selector switch to the current block, connect the watch pen in series in the circuit, and the measured current is read out on the second scale line.

Measurement of DC voltage: turn the selector switch to the corresponding voltage block, divide the watch pen into positive and negative and connect it to the circuit, and the measured current is read out on the second scale line.

Measurement of AC voltage: Screw the selector switch to the corresponding voltage block, the AC block is read out on the third scale line, and the rest is read out on the second scale line.

When it is finished, screw the selector switch to the highest AC voltage setting.

Precautions for multi-metering:

a.When measuring current and voltage, it is not possible to change the range with electricity.

b.When selecting the range, you should choose the large one first, and then the small one, so that the measured value is as close to the range as possible.

c.When measuring resistance, it cannot be measured live.

d.After use, the transfer switch should be in the maximum gear or neutral gear of the AC voltage.

How to use multiple meters.

The multi-purpose meter is also called a three-purpose meter, which is generally used to measure current, voltage and resistance, so it is also called a three-purpose meter. Due to the large range, it is also called a multimeter.

1. Let's talk about the current measurement first: the multi-meter current measurement is similar to the current meter in physics, which is connected in series in the circuit under test. It is also necessary to estimate the measured current before connecting it into the circuit.

If you don't know, try to use a large current range, and adjust the range appropriately according to the pointer deflection angle. Generally, the watch hand is most sensitive and accurate at half of the full level.

2. Let's talk about voltage: it is similar to the current measurement, but it is connected in parallel with the circuit under test.

3. Finally, let's talk about resistance measurement: the measurement of resistance value is divided into on-circuit measurement and open-circuit measurement. On-circuit measurement refers to the measurement of the resistance between two points or the resistance of a certain component, without removing it, and measuring the resistance between its pins.

Open circuit measurement is the process of removing the original or leaving only one pin and then measuring the resistance between the pins. Due to the polarity of the battery in the table, it is generally necessary to change the meter pen after the measurement is completed for a second comparison. It is also necessary to change the measuring range to achieve the purpose of measurement.

Before the resistance measurement, it must be zeroed, and the gear shift must be adjusted to zero once. If you find that the deflection angle of the meter head is too large, you should adjust the resistance gear to a smaller level, which is the opposite of measuring the current and voltage.

Precautions: 1. When measuring voltage and current, once it is found that the watch needle hits the head, there is a tendency to exceed. Immediately remove the pen and change to a larger range for re-measurement.

2. When measuring whether the capacitor is leaking, the capacitor should be discharged and then measured to avoid damage to the multimeter.

3. When measuring the resistance value on the road, it should be measured again after the power is off.

4. When measuring the current and voltage, do not convert the range while measuring, and should change the range after the pen is removed from the circuit.

5. Be careful not to use the resistor to measure the live circuit.

I read the manual at the watch, and the upstairs is a note

The principle and use of multi-meter are as follows:

1. The principle of multi-meter.

1) The principle of measuring DC current and DC voltage is the same as that of DC ammeter and DC voltmeter.

2) Measuring resistance: The principle of the internal circuit is shown in the figure on the right, and its principle is measured according to Ohm's law of the closed loop, that is, i=e (rg+r+r+rx), in which all are fixed-value resistances, and different rx correspond to different currents i (of course, the relationship between current i and the measured resistance rx is not proportional, so the scale of the resistance value is not uniform). If the resistance Rx value corresponding to the current i is directly marked on the dial, the resistance value of the measured resistance can be read directly from the dial.

(3) "Zeroing" principle: when the two meters are in contact, rx=0, the current is adjusted to the full offset value (maximum), and the corresponding resistance value is zero.

4) The median resistance is the internal resistance of the multi-meter resistance file, when the measured resistance rx=rg+r+r, the current through the meter head, that is, the current through the meter head is half of the full bias current, at this time the pointer points to the ** of the dial, so the internal resistance of the resistance file is generally called the median resistance.

2. How to use the multi-purpose table.

1) When measuring the current, like the ammeter, the multimeter should be connected in series in the circuit under test, and for direct current, the current must flow from the red meter pen into the multimeter and out of the black meter pen.

2) When measuring voltage, like the voltmeter, the multimeter should be connected in parallel at both ends of the circuit under test, for direct current, the red meter pen must be connected to the point with higher potential, and the black meter pen must be connected to the point with lower potential.

(3) When measuring the resistance, after selecting the gear, the two watch pens should be in contact with each other, adjust the zero knob of the resistance file, so that the pointer points to the zero position of the resistance scale, and then connect the two watch pens with the two ends of the resistance to be measured. It should be noted that when switching to another range in ohms, the zeroing knob of the resistance level needs to be readjusted in order to take the measurement.

The principle and use of multi-meter are as follows:

1. The principle of multi-meter.

Multi-meter meters can be used to measure current, voltage, resistance, etc., and each measurement has several ranges. The principle on which the current and voltage measurement of multi-meter is based is the characteristics of series and parallel circuits and Ohm's law of some circuits. The ohmmeter is the resistance measurement block of the multimeter.

The principle on which ohmic meters measure resistance is Ohm's law for closed circuits.

2. Instructions for the use of multi-meter:

Mechanical zeroing inserts the red and black watch pens into the "+" jack respectively. Use a small screwdriver to turn the mechanical zeroing knob until the pointer points to zero. When measuring the current, turn the selector switch to the current stop, and select the appropriate range according to the estimated current.

The voltage measurement will connect the meter in parallel at both ends of the circuit to be measured, the red table pen will be connected to the high potential, and the black meter pen will be connected to the low potential.

Measure the resistance of the resistor to be measured, select the appropriate ohmic gear, and make the pointer point to the zero position of the ohmic scale. The measurement and reading will be connected to the red and black watch pens respectively with the two ends of the resistance to be measured, and the number of the watch hand is multiplied by the magnification of the selected ohmic stop, which is the resistance value of the resistor.

Precautions for multi-meter: Do not rotate the range selection knob during the test. The watch pen must be inserted into the jack of the multi-meter in strict accordance with the color, red is "+" and black is "-" When measuring, the human body must not touch the metal parts of the meter pen, so as to ensure the accuracy of the measurement and personal safety.

1) Observe the shape of the multi-meter, and understand the measurement items and range of the selector switch; (2) Check whether the pointer of the multimeter stops at the zero position at the left end of the dial scale. If it does not point to zero, you can use a small screwdriver to adjust the mechanical zeroing knob to make the pointer point to zero; (3) Insert the red and black watch pens into the "+" jack respectively; 2. Voltage measurement (4) Place the selector switch in the DC voltage block to measure the voltage of the dry battery; (5) Put the selector switch in the AC voltage 250V gear and measure the AC voltage of 220V; 3. Current measurement (6) place the selector switch in the DC current 10mA stopper to measure the current of the dry battery and the 200 resistance series circuit; 4. Measuring resistance (7) put the selection switch in the "1" gear of the ohmic meter, short the red and black watch pen, turn the knob to adjust the zero point of the ohmmeter, so that the pointer points to the zero position of the ohmic scale. (8) Contact the two meter pens to the two ends of the fixed value resistance of a few ohms and tens of ohms respectively, read out the resistance value indicated by the ohm meter, compare it with the standard value, and then disconnect the meter pen.

9) Set the selector switch to the "100" gear of the ohmic stop, readjust the ohmic zero point, and then measure the resistance of a few hundred ohms or several thousand ohms, and compare the measured value with the standard value. 5. Measuring the forward and reverse resistance of the diode (10) First of all, we should clarify two wide pre-book problems: The unidirectional conductivity of the diode.

The resistance of current flowing from the positive electrode is small, and the resistance is greater when flowing out of the positive electrode. The direction of the current in the ohmmeter. It flows out of the black watch pen, passes through the resistance to be measured, and flows in from the red watch pen.

Hello, I'm glad to answer for you, the principle of multi-meter: multi-meter can be used to measure current, voltage, resistance, etc., and each measurement has several ranges; The principle based on which the current and voltage measurement of the multi-meter is based is the characteristics of the series and parallel beam circuits and the Ohm's law of some circuits. The ohmmeter is the resistance measurement block of the multi-meter, and the principle on which the ohmmeter measures the resistance is based is Ohm's law of closed circuits; Precautions for the use of multiple meters:

1.When measuring DC current, the circuit to be measured should be disconnected first, and then the multimeter should be measured in series in the circuit to be measured. Do not misuse the current to measure the voltage.

2.Regardless of the measurement, the two Career Change Switches must be turned into the correct position. Especially when selecting measurement items, you should not make mistakes.

For example, misusing an ohmic or DC current to measure voltage can cause the meter to burn out immediately. 3.When operating, it is not allowed to touch the metal part of the watch pen with your hands.

When one pen is in contact with the power supply, the other pen is also charged at the same time, and if you don't pay attention, there is a risk of electric shock.