Capacitor Code Guide
When I first started doing electronics, capacitors ("caps") were a real puzzle, and I often just substituted them in a breadboarded circuit until I found one that worked. Finally it occurred to me to do up this chart. Now I have a DMM that reads capacitance, which makes identifying capacitors much simpler.
- A Farad is the measure of electronic capacitance.
- Named in honor of scientist Michael Faraday , a pioneer in electronics---http://indykfi.atomki.hu/indyKFI/MT/orig_si.htm
- The Farad is a HUGE quantity, and most capacitors are only a fraction of a Farad.
- BEAM projects typically use caps between .001uF and 47uF for timing, signal conditioning, and power filtering; and between 1000uF and 1F for storage in solar engines.
pF = picoFarad, 10-12 farad (that's one trillionth!) 1 uF = 1 000 000 pF
uF = microFarad (the letter u substitutes for the Greek letter micron) 1 F = 1 000 000 uF
mF = microFarad (not milliFarad as you'd expect) 1 F = 1 000 000 000 000 pF
Capacitor values are usually standardized--.10,.22, .33, .47 and so on. However, you might occasionally find an unusual value such as 0.15 or 0.27. You can generally substitute one of these for a single cap in a given circuit. BEAM circuits are often bilateral (two-sided) and balanced, and in these cases try to use the same value on both sides.
The codes below are generally found on ceramic (little round discs) and mylar (chicklet) capacitors, which are not polarized, that is, there are no positive and negative leads.
Usually the first two digits of the code represent part of the value; the third digit corresponds to the number of zeros to be added to the first two digits. This is the value in pf. Some values are usually given in uF, especially those used in BEAM applications, so I have given these as a separate column where appropriate.
VALUE(pF) CODEVALUE(pF) VALUE(uF) CODE 1.5pF 1,000pF .001uF 102 3.3pF 1,500pF .0015uF 152 10pF 2,000pF .002uF 202 15pF 2,200pF .0022uF 222 20pF 4,700pF .0047uF 472 30pF 5,000pF .005uF 502 33pF 5,600pF .0056uF 562 47pF 6,800pF .0068uF 682 56pF .01uF 103 68pF .015 75pF .02 203 82pF .022 223 91pF .033 333 100pF 101 .047 473 120pF 121 .05 503 130pF 131 .056 563 150pF 151 .068 683 180pF 181 .1 104 220pF 221 .2 204 330pF 331 .22 224 470pF 471 .33 334 560pF 561 .47 474 680pF 681 .56 564 750pF 751 1 105 820pF 821 2 205
Tantalum (teardrop shaped) and electrolytic (little cans) capacitors are polarized, so you have to watch what is the positive and negative lead. They are generally higher values and usually have the value printed right on them
