Table 1 – Capacitor codes with letters and tolerances 3rd number 3R9 where R is a indicator of values below 10pF and have nothing to do with resistance. Some small capacitance capacitors can be marked with a R between numbers, f.ex. Some capacitors are only marked 0.1 or 0.01, mostly in these cases the values are given in uF. 2A is 100VDC rating according to the EIA standard. marked 2A474J, the capacitance is decoded as described above, the two first signs is the voltage rating and can be decoded from table 2 here below. Judging by a capacitors size and type, you will quickly learn to determine if the value on the capacitor is given in pF, nF or uF. A second letter will be a temperature coefficient if its present. Looking at our capacitor we will see its marked 474J, this should be read as follows, 47 times the value that can be found in Table 1 corresponding to the 3rd number, in this case 10000. Suitable to be used for high frequency filtering, outdoor applications where moisture can be a problem, high voltage or current peaks in circuits and coupling and de-coupling circuits. Low ESR and can operate at temperatures up to 125☌, without much voltage derating. Known as Mylar, Polyester or Polyethylene terephthalate PET capacitors. The dielectric has a maximum operating temperature of +85☌. Suitable for precision-tuned circuits due to the extreme stability in the 0☌ thru +50☌ range and it has long-term stability. A metalized version was unsuccessful due to the low melting point of the dielectric. Metal foil and Polystyrene dielectric film. High internal resistance results in low levels of self discharge. Suitable for high power AC circuits, circuits with high peak currents, high frequency resonant circuits, precision timing circuits, switch mode power supplies, sample and hold circuits, high frequency pulse discharge circuits and energy storage circuits. Very Low ESR, high stability and can found in 1% tolerance versions and can operate at temperatures up to 110☌. Small size, high Q and capacitance stability make them ideally suited to filter network and other low-loss high frequency applications. Extremely temperature stable with less than 1% capacitance tolerance between -55✬ to +125✬.
Metal foil and Polypropylene dielectric film. Metal foil and Polycarbonate dielectric film.