How to determine the polarity of the chip tantalum capacitor (how to distinguish between positive and negative tantalum capacitors)

Tantalum capacitor

One end of the chip tantalum capacitor is marked with a horizontal line, which is the positive pole of the tantalum capacitor, and the other end is the negative pole. The end of the lead tantalum capacitor leg is the positive pole, and the short end of the leg is the negative pole.

The chip tantalum capacitor is a polar capacitor, and the positive and negative poles cannot be reversed. In case of a reverse connection, the tantalum capacitor does not function or fails.

The positive and negative poles of the tantalum capacitor are distinguished and the black block with the mark on the tantalum capacitor is the negative pole. There are two semicircles on the position of the capacitor on the PCB, and the pin corresponding to the semicircle of the color is the negative pole. Also use the length of the pin to distinguish the positive and negative long legs from positive and the short legs to negative.

When we don't know the positive and negative poles of the tantalum capacitor, we can use a multimeter to measure. The medium between the two poles of the capacitor is not an absolute insulator, its resistance is not infinite, but a finite value, generally above 1000 megaohms. The resistance between the two poles of the capacitor is called insulation resistance or leakage resistance, only electrolytic capacitor When the positive pole is connected to the power supply (black pen when the power is blocked) and the negative terminal is negative (the red test pen when the power is blocked), the leakage current of the electrolytic capacitor is small (the leakage resistance is large).

1, the symbol of the capacitor

The symbol of the capacitor is also divided into the domestic standard representation and the international electronic symbol representation, but the capacitance symbol is similar in both domestic and international representations. The only difference is that in the case of a polar capacitor, the domestic is an empty basket below a horizontal line. And the international is the ordinary capacitor plus a "+" symbol to represent the positive.

2, the unit of capacitance

The basic unit of capacitance is: F (method), in addition to μF (micro method), pF (pesh method), there is also a relatively small unit used, DSC00187 that is: nF (), due to the capacity of the capacitor F Very large, so what we see is generally the unit of μF, nF, pF, not the unit of F.

The specific conversion between them is as follows:

1F=1000000μF

1μF=1000nF=1000000pF

In practical applications, because the above values ​​are large, the abbreviations are used, that is, the "0" following the capacity is indicated by the actual number of bits, for example:

100μF can be written as 107 pF, 10μF can be written as 106 pF, 1μF can be written as 105 pF, 47μF can be written as 476 pF

470000 pF can be written as 474 pF, 10000 pF can be written as 103 pF, 1000 can be written as 102 pF and so on.

On the contrary, the leakage current increases (the leakage resistance decreases). Let us assume that an extremely "+" pole, the multimeter uses R*100 or R*1K, and then assumes the "+" pole and the black meter of the multimeter. Connect, the other electrode is connected with the red test lead of the multimeter, and the scale of the lower needle stop is recorded (the needle has a large left resistance value). For the digital multimeter, the reading can be directly read, and then the capacitor is discharged (the two leads are touched) Then, the two test leads are reversed and re-measured. In the two measurements of DSC00192, the position where the needle stays last is left (or the resistance is large), and the black meter is connected to the positive electrode of the electrolytic capacitor.