When repairing electronic product, we see via regular meeting mark is worn above capacitance of on circuit board a few ceramics 101, 223, these 104 numbers, are a lot of abecedarian done what meaning are these numbers of mark after all above not clear capacitance? Actually this is a kind of indicative method of capacitance capacity. We introduce the indicative method of capacitance capacity and error in detail below.
1, the indicative method of capacitance capacity
The indicative method of capacitance capacity is direct and indicative law and digital designation law commonly usedly now. Average volume is larger electroanalysis the capacity of capacitance uses direct and indicative method, tag capacitance directly namely go up in housing, and lesser to bulk ceramics capacitance, alone stone capacitance, tantalum capacitance uses 3 digit word to represent its capacity mostly. 0.1 μ of ▲ the ceramics capacitance of F.
When express capacitance with 3 digit word, word of before two digit is this capacitance nominal the significant numerical value of the value, the 3rd expresses to a number of 0 is increased at the back of significant numerical value. For example, above the ceramics capacitance in pursueing on of mark " 104 " , here " 10 " be worth for significance, tertiary " 4 " , express " 10 " from the back add 4 0, namely 100000pF (when expressing capacitance with 3 digit word, its unit is PF) . We know, 1000nF of ＝ of 1 μ F, 1nF ＝ 1000pF, the 104 capacities that represent this electric capacity are reason 100nF or 0.1 μ F. The ceramics capacitance of ▲ 22pF.
Be in to capacitance the small electric capacity under 100pF (this kind of capacitance is capacitance of high frequency ceramics mostly) , use law of 3 digit word to express its capacitance no longer commonly, tag capacitance directly however go up in housing. For example, the ceramics capacitance of the 22pF that plan institute shows on, it is directly above capacitance tag " 22 " , the capacity that represents this electric capacity namely is 22pF.
By the way, the capacitance of high frequency ceramics of this kind of small size, the capacity is stable, high frequency performance is good, multi-purpose in high frequency circuit. The coping of this kind of capacitance besmears commonly a small scene is nodded, this color nods the temperature coefficient that represents this electric capacity, among them the temperature coefficient that black quality point represents this electric capacity is 0, its capacitance suffers environmental temperature the impact is very little.
2, the expression of capacitance error method0.47 μ of ▲ the polypropylene capacitance of F/400V.
To polyester fibber capacitance, polypropylene capacitance, besides express its with 3 digit word besides capacitance, this kind of capacitance uses the letter such as J, K, M to show its error commonly. Among them, "J " the error that shows this electric capacity is 5% , "K " state the error is 10% , "M " state the error is 20% . The polypropylene capacitance in pursueing on is tagged for " 474J " , the capacity that represents this electric capacity is 0.47 μ F, the error is 5% .
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