Precautions for multimeter measurement accuracy
Human reading error is one of the reasons that affect the measurement accuracy. It is unavoidable but can be minimized. Therefore, pay special attention to the following points during use:
(1) Keep your eyes perpendicular to the pointer when reading;
(2) Before measurement, place the multimeter horizontally and perform mechanical zero adjustment;
(3) When measuring resistance, zero adjustment must be performed every time a gear is changed. Replace the battery with a new one when the adjustment is less than zero;
(4) When measuring the resistance in the RC circuit, cut off the power supply in the circuit, discharge the electricity stored in the capacitor, and then measure. After excluding the human-made reading errors, we conduct some analysis on other errors;
(5) When measuring resistance or high voltage, do not pinch the metal part of the test lead with your hands, so as to avoid shunting of human body resistance, increasing measurement error or electric shock.
Digital multimeters are also known as digital multimeters (DMMs), and there are many types and models. Every electronic worker hopes to have an ideal digital multimeter. There are many principles for choosing a digital multimeter, and sometimes they even vary from person to person. However, for a handheld (pocket) digital multimeter, it should generally have the following characteristics: clear display, high accuracy, strong resolution, wide test range, complete test functions, strong anti-interference ability, relatively complete protection circuit, and beautiful appearance , generous, easy to operate, flexible, good reliability, low power consumption, easy to carry, moderate price and so on.
How to measure whether the piezoelectric ceramic is damaged with a multimeter
The multimeter is composed of three main parts: meter head, measuring circuit and changeover switch. The multimeter is the most basic tool in the field of electronic testing, and it is also a widely used testing instrument. Multimeters are also called multimeters, three-purpose meters (A, V, Ω are current, voltage, and resistance), multimeters, and multimeters. Multimeters are divided into pointer multimeters and digital multimeters. There is also a multimeter with oscilloscope function. The oscilloscope multimeter is a multi-functional, multi-range measuring instrument.
General multimeters can measure DC current, DC voltage, AC voltage, resistance and audio level, etc., and some can also measure AC current, capacitance, inductance, temperature and some parameters of semiconductors (diodes, triodes). Digital multimeters have become mainstream and have replaced analog meters. Compared with analog instruments, digital instruments have high sensitivity, high precision, clear display, strong overload capacity, easy to carry, and more convenient and simple to use. Let the editor of Electrician's House introduce the method of using a multimeter to judge whether the piezoelectric ceramic is damaged.
Piezoelectric ceramics are a synthetic piezoelectric material. When subjected to external pressure, charges will be generated on both sides, and the amount of charge is proportional to the pressure. This phenomenon is called piezoelectric effect. Piezoelectric ceramics have a piezoelectric effect, that is, they will deform under the action of an external electric field, so piezoelectric ceramic sheets can be used as sounding components.
Utilizing the piezoelectric effect of the piezoelectric ceramic sheet, a multimeter can be used to judge whether it is good or bad.
Lead out two wires from the two poles of the piezoelectric ceramic sheet, then place the ceramic sheet flat on the table, connect the two lead wires to the two test leads of the multimeter, turn the multimeter to the minimum current position, and then lightly press the ceramic sheet with the rubber tip of a pencil , if the pointer of the multimeter swings obviously, it means that the ceramic chip is intact, otherwise, it means it is damaged.
