The type of capacitor is different, and its design structure and principle will be very different. From a macro perspective, capacitors can be divided into polar and non-polar capacitors. For polar capacitors, the accuracy of the positive and negative electrodes must be ensured during installation. An error in the connection can result in damage to the capacitor or even an explosion. For capacitors without polarity, you don't need to worry about this. So, is there a positive and negative pole for the ceramic capacitor? How to tell if there is extreme?
It is a non-polar capacitor, so this capacitor does not need to distinguish between positive and negative during installation. For ordinary common grade electrolytic capacitors, you can see the length of the two feet, the length is +, the short is -. The chip type tantalum electrolytic capacitor can generally be judged according to its appearance, and one side of the colored ribbon is a positive electrode. Other non-polar electrolytic capacitors, polyester/tantalum capacitors, ceramic capacitors, variable and trimmer capacitors have no positive and negative poles.
The difference between the positive and negative capacitors can be judged according to the following method. When you do not know the positive and negative poles of the capacitor, you can use a multimeter to measure. The medium between the two poles of the capacitor is not an absolute insulator, and its resistance is not infinite, but a finite value, generally above 1000 megohms. The resistance between the two poles of the capacitor is called an insulation resistance or a leakage resistance. Only when the positive electrode of the electrolytic capacitor is connected to the power supply (the black test pen when the power is blocked), and the negative terminal is connected to the negative power supply (the red test pen when the power is blocked), the leakage current of the electrolytic capacitor is small (the leakage resistance is large). On the contrary, the leakage current of the electrolytic capacitor increases (the leakage resistance decreases).
You can assume that a very "+" pole, the multimeter uses R*100 or R*1K, then the hypothetical "+" pole is connected to the black meter of the multimeter, and the other electrode is connected with the red meter of the multimeter. The scale of the needle stop (the needle has a large left resistance value), and the reading can be directly read out for the digital multimeter. Then discharge the capacitor (two leads touch), then the two test leads are reversed and the measurement is repeated. In the two measurements, the last position of the hand is left (or the resistance is large), and the black pen is connected to the positive electrode of the electrolytic capacitor.
In general, the ceramic capacitor has no positive and negative poles, and the capacity is generally small. It is often used for signal source filtering, and the polarity is only temporary behavior. This is a kind of non-polar electrolytic capacitor, so it is not polar. Therefore, the identification of the positive and negative poles is not required during the installation process, and can be installed at will.