Types of multimeters and how to use them

The multimeter is a great helper in maintenance electricians, machine tool repairs, mobile phone repairs and information equipment repairs. Here we will introduce the types of multimeters and how to use them.

Multimeters are divided into magnetoelectric pointer multimeters and LCD digital multimeters. We mainly introduce pointer multimeters. There are five types of pointer multimeters, including MF-10, MF-35, MF-47, MF-50 and MF-500. Among them, the 10 type has high sensitivity and is more suitable for microelectronics technicians. The 35 type has high accuracy but is expensive and not suitable for common use. The 47 type multimeter is especially introduced. It has high sensitivity, accuracy and functions. It has a protection circuit inside and can measure 2500 volts of high voltage, transistor magnification, capacitance and even some can test the quality of infrared remote controls. The 50 type is suitable for common use, while the 500 type has high accuracy but is large in size and not easy to carry and is only suitable for fixed use. The internal circuits of the multimeters mentioned above are basically the same, all of which are composed of various resistors, such as color ring resistors, winding resistors, etc., and also contain some diodes and other components for rectification. The "heart" of the multimeter is its head, so when using and maintaining the multimeter, it should not be subjected to large vibrations or impacts! So as not to affect its accuracy!

Next, let's learn how to use a multimeter. The use of a multimeter must follow certain principles and operating procedures, otherwise it is easy to damage the multimeter! Before using it, you need to adjust the multimeter. First, observe whether the pointer of the multimeter is aligned with the zero scale line on the left. If it is not coincident, you need to perform "mechanical zero adjustment". The method is to use a screwdriver of appropriate size to adjust the mechanical zero adjustment knob until the pointer coincides with the 0 scale line. After debugging, you must follow certain steps to measure, that is, "one look, two pull, three test, four measure, five reset". "One look" means to check whether the test leads are connected correctly and whether the gear is correct; "two switches" means to turn the conversion switch to the appropriate range, especially when measuring current, you must be very careful not to connect across the two ends of the power supply; "three tests" means to use the test leads to briefly touch the components under test (especially when measuring voltage and current) before measurement and observe the amplitude of the pointer deflection. If the amplitude is large, change the range to a larger range and then measure again; "four measurements" means you can measure on the basis that the previous steps have been carried out normally; "five resets" means after the measurement, turn the conversion switch to the highest gear for measuring AC voltage to avoid burning the meter due to forgetting to check the gear next time you use it!

When measuring resistance, the resistance must be disconnected from the power supply before measurement. Short-circuit the two test leads before measurement. The resistance should be zero at this time. The 0 scale line of the resistance value is usually at the far right end (the pointer deflects the maximum to the zero scale line at the right end). If the pointer does not coincide with it, you can adjust the "resistance range zeroing knob" with the symbol "Ω" (actually an adjustment potentiometer). Each time the resistance range is changed, "zeroing" must be performed to accurately read the value.