The correct application method and precautions for pointer multimeter
Multimeter, also known as multi-meter, triple meter, multipurpose meter, multimeter is divided into pointer multimeter and digital multimeter lead. It is a multi-functional, multi-range measurement instrument, the general multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc., and some can also measure AC current, capacitance, inductance and semiconductors of some parameters
Methods / Steps
Mechanical zeroing and ohmic zeroing. In order to reduce the measurement error, the multimeter should be mechanically zeroed before using it (usually adjusted only once at the first use). In the use of ohm block resistance measurement, the first ohm zero (i.e., electrical zero), that is, the two pens shorted, adjust the "zero ohm" adjustment knob, so that the multimeter pointer to the * right end of the 0 ohms, if you can't make the pointer to reach the 0 ohms, usually due to insufficient voltage of the batteries in the table, should be replaced with new batteries before measurement. If it is not possible to make the pointer reach 0 ohm, it is usually due to insufficient battery voltage in the meter, and should be replaced with new battery before measurement. In the future, every time you change the range (gear), you have to carry out ohm zero adjustment.
In the process of use, it is strictly prohibited to measure the resistance with the ohmic block when the measured resistance is electrically charged, otherwise, the applied voltage will easily cause damage to the multimeter or trigger an accidental failure of the circuit.
Correct wiring. As the multimeter DC head only allows current to flow from the "+" pole, from the "one" pole out, so the multimeter panel jacks and terminals are marked with polarity. When using the red pen and "+" polarity jack connected to the black pen and "a" polarity jack connected. Measurement of DC voltage and DC current, pay attention to the positive and negative pen polarity shall not be reversed, so as to avoid reversal of the pointer, such as the pointer is found to reverse, you should immediately change the pen. When measuring current, the meter should be IPP45N06S3L-13 connected in series in the circuit under test; when measuring voltage, the meter should be connected in parallel at both ends of the circuit under test. When measuring transistors with a multimeter, it should be kept in mind that the red pen of the multimeter is connected to the negative terminal of the internal battery and the black pen is connected to the positive terminal of the internal battery.
The measurement stops should be correctly selected. Measurement stops include the measurement object and range. For example, when measuring voltage, the change-over switch should be placed in the corresponding voltage block, and when measuring current, it should be placed in the corresponding current block, etc. If the current block is mistakenly used to measure voltage, it should be used to measure current. If the current block is mistakenly used to measure voltage, it will cause damage to the instrument. When selecting the current or voltage range, the pointer should be in the position of more than 2/3 of the scale; when selecting the resistance range, it is best to make the pointer in the middle of the scale. The purpose of doing so is to minimise the measurement error. Measurement, when you can not be sure of the measured current, voltage value range, you should first switch to the corresponding * large range, and then according to the degree of deflection of the pointer gradually reduced to the appropriate range.
Read the meter correctly. There are many scales on the dial of the multimeter, which are used for different measurement objects. Therefore, the measurement should be read on the corresponding scale, and at the same time, attention should be paid to the scale reading and range of the scale, that is, the "reading" and "measured value" on the scale of the meter head should not be confused together, "reading" means to read from the scale, "reading" means to read from the scale. "refers to the value read directly from the scale, and" measured value "is the value of the readings represented by the measured value, it is often obtained by conversion, although sometimes the two are numerically the same, but in many cases are different. In addition, the reading should be taken in such a way that the pointer and the projection of the pointer on the reflector overlap in order to avoid measurement errors.
