How to Decouple Capacitor Values
- 1). Inspect the capacitor for markings. If the markings are alphanumeric, the capacitance will be indicated with a numerical representation, such as 4.5 MFD -- indicating 4.5 microFarad -- with a number or letter indicating tolerances. If letters are used, D represents 0.5 picoFarad of tolerance. F indicates 1 percent tolerance, G is 2 percent, H is 3 percent, J is 5 percent, K is 10 percent and M represents 20 percent.
- 2). Read the color codes from left to right. Compare the color codes to a capacitor decode chart. Just as with numbers or letters, the color bands represent the capacitance, tolerance and if a fifth color is present, voltages.
- 3). Determine the multiplier. If there are three bands only, or three bands separated from other bands by a large space, the first position is the numerical value, the second is the multiplier and the third is the tolerance. If there are four bands in the first set of bands, the third band is the multiplier. A multiplier indicates the number of zeros added to the digits indicated by the first color bands. For example, colors indicating a 3 and a 5 followed by a color indicating a 2 produce the number 3500.
- 4). Decouple the color bands to determine the voltage. The space appearing between the first set of colors and the last set allows decoding of the voltage. The last color or two colors are the digits representing the voltage of the capacitor. For example, a red band in the fifth position represents 200 volts.
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