Two tips for using a multimeter
Using a multimeter to determine the quality of piezoelectric ceramics
Piezoelectric ceramics are artificially synthesized piezoelectric materials. When subjected to external pressure, charges are generated on both sides, and the amount of charge is proportional to the pressure. This phenomenon is called the piezoelectric effect. Piezoelectric ceramics have a piezoelectric effect, that is, under the action of an external electric field, they will undergo deformation, so piezoelectric ceramic sheets can be used as sound emitting components.
By utilizing the piezoelectric effect of piezoelectric ceramic sheets, a multimeter can be used to determine their quality.
Lead out two wires from the two poles of the piezoelectric ceramic sheet, then place the ceramic sheet flat on a table, connect the two wires to the two probes of the multimeter, set the multimeter to the low current range, and gently press the ceramic sheet with a pencil eraser. If the pointer of the multimeter swings significantly, it indicates that the ceramic sheet is intact; otherwise, it indicates that it is damaged.
Use a multimeter to determine the positive and negative poles of the speaker
Firstly, set the pointer type multimeter to DC 0-5mA range, and then connect the two probes to the two solder pads of the speaker to be tested. Gently press the paper bowl of the speaker with your hand and observe the direction of the multimeter pointer's swing. If the pointer is deflected in the positive direction, the red probe is connected to the negative pole of the speaker, and the black probe is connected to the positive pole of the speaker. On the contrary, the red probe is connected to the positive pole, and the black probe is connected to the negative pole.
Is a digital multimeter necessarily better than an analog multimeter?
Solution: Digital multimeters have been rapidly applied due to their high accuracy and sensitivity, fast measurement speed, multiple functions, small size, high input impedance, ease of observation, and powerful communication capabilities. There is a trend towards replacing analog pointer tables.
But in certain situations, such as when electromagnetic interference is very strong, the data tested with a digital multimeter may have a significant deviation because the input impedance of the digital multimeter is very high and is easily affected by induced electromotive force.
