Use a multimeter to distinguish the positive and negative poles of the speaker
First, set the pointer multimeter to the DC 0~5mA range, and then connect the two test leads to the two solder tabs of the speaker to be tested. Press the paper cone of the speaker gently with your hand and observe the swing direction of the multimeter pointer. If the pointer deflects in the positive direction, the red test lead is connected to the negative electrode of the speaker and the black test lead is connected to the positive electrode of the speaker. On the contrary, the red test lead is connected to the positive pole, and the black test lead is connected to the negative pole.
First, set the pointer multimeter to the DC 0~5mA range, and then connect the two test leads to the two solder tabs of the speaker to be tested. Press the paper cone of the speaker gently with your hand and observe the swing direction of the multimeter pointer. If the pointer deflects in the positive direction, the red test lead is connected to the negative electrode of the speaker and the black test lead is connected to the positive electrode of the speaker. On the contrary, the red test lead is connected to the positive pole, and the black test lead is connected to the negative pole.
How to judge the quality of piezoelectric ceramics with a multimeter
Piezoelectric ceramic is 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 the 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 sound-generating components.
Using the piezoelectric effect of the piezoelectric ceramic piece, a multimeter can be used to judge its quality.
Lead two wires from the two poles of the piezoelectric ceramic piece, then place the ceramic piece flat on the table, connect the two leads to the two test leads of the multimeter, set the multimeter to the minimum current block, and then lightly press the ceramic piece with the pencil eraser. , if the pointer of the multimeter swings obviously, it means that the ceramic piece leads two wires from the two poles of the piezoelectric ceramic piece. Then place the ceramic piece flat on the table, connect the two leads to the two test leads of the multimeter respectively, and set the multimeter to the minimum current block. , and then press the ceramic piece lightly with the pencil eraser. If the multimeter pointer swings obviously, it means the ceramic piece is intact, otherwise, it means it is damaged.
In good condition, otherwise, it means it is damaged.
