Analysis of the method of measuring the resistance value of the multimeter:
There are quite a lot of components used in the industry, each of which will have different usage requirements when used. As a multimeter commonly used in the industry, people also need to pay attention when using it. The main content of this article is to pay attention to the problems that need to be paid attention to when using a multimeter to measure the resistance value of the resistance. Let's take a look.
Multimeters are divided into traditional multimeters and digital multimeters. Traditional multimeters are of the electromagnetic deflection type with pointers. Mechanical zero adjustment is required before each use. It is cumbersome to use and the reading of the indicated numbers is subjective and inaccurate. It is rare now. Use; and digital multimeters can directly display numbers without observing the scale for reading, the results are more accurate, and are currently widely used.
Precautions when measuring resistance with a multimeter:
(1) Before using the multimeter, "mechanical zero adjustment" should be performed first, that is, when there is no electricity to be measured, make the pointer of the multimeter point to the position of zero voltage or zero current.
(2) In the process of using the multimeter, do not touch the metal part of the test pen with your hands, so on the one hand, it can ensure the accuracy of the measurement, and on the other hand, it can also ensure personal safety.
(3) When measuring a certain amount of electricity, you cannot change gears while measuring, especially when measuring high voltage or high current, you should pay more attention. Otherwise, the multimeter will be destroyed. If you need to change gears, you should disconnect the test leads first, and then go to measure after changing gears.
(4) When the multimeter is in use, it must be placed horizontally to avoid errors. At the same time, pay attention to avoid the influence of external magnetic fields on the multimeter.
(5) After the multimeter is used, the transfer switch should be placed in the maximum block of AC voltage. If it is not used for a long time, the battery inside the multimeter should also be taken out to prevent the battery from corroding other components in the meter.
A multimeter is a multi-function, multi-range measuring instrument. It can not only measure the resistance of the object to be measured, but also measure the DC voltage. As an important measurement tool in the industry, only by knowing the points to be paid attention to during measurement can it play its role better.
How to detect the photoresistor?
1. Cover the light-transmitting window of the photoresistor with a black piece of paper. At this time, the pointer of the multimeter remains basically unchanged, and the resistance value is close to infinity. The larger the value, the better the performance of the photoresistor. If this value is very small or close to zero, it means that the photoresistor has been burnt through and damaged and can no longer be used.
2. Aim a light source at the light-transmitting window of the photoresistor. At this time, the pointer of the multimeter should have a large swing, and the resistance value will be significantly reduced. The smaller the value, the better the performance of the photoresistor. If this value is very large or even infinite, it indicates that the internal open circuit of the photoresistor is damaged and cannot be used any longer.
3. Align the light-transmitting window of the photoresistor with the incident light, and use a small black piece of paper to shake the upper part of the light-shielding window of the photoresistor to make it receive light intermittently. At this time, the pointer of the multimeter should swing left and right with the shaking of the black piece of paper. If the pointer of the multimeter always stops at a certain position and does not swing with the shaking of the paper, it means that the photosensitive material of the photoresistor has been damaged.
