capacitor decode page

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Identify your original capacitors!What is polarity? An electrical condition determining the direction in which current tends toflow. Hence, negative (-), positive (+).

What does "almost always" mean? There are always exceptions. You may find one markeddifferently, who knows!!

What Exactly Is A Capacitor? How Do We Read ThesesThings?

The basic unit of capacitance is the Farad, named after the Michael Faraday.Capacitance is usually measured in microFarads, abbreviated µF, or picoFarads (pF). Theunit Farad is used in converting formulas and other calculations. A µF (microFarad) is onmillionth of a Farad (10-6 F) and a pF picoFarad is one-millionth of a microFarad (10-12

F). A capacitor is a device that stores an electrical charge or energy on it's plates. These

plates are placed very close together with an insulator in between to prevent the plates fromtouching each other, and a type of dielectric. A capacitor can carry a voltage equal to thebattery or input voltage. Usually a capacitor has more than two plates depending on thecapacitance or dielectric type. Once charged the discharge rate can be influenced byanother source. This action can create oscillation, or be used for electronic timing. The ratein witch the capacitor charges and discharges can be used to create a filter, or limitunwanted noise. There is lots more we can do with capacitors too.

Capacitor Codes:

I guess you would really like to know how to read all those different codes. Not toworry, it is not as difficult as it appears. Some capacitors just tell you right out. Take yourelectrolytic and large body types of capacitors: these usually have the value printed on thebody of the cap. For example,:100µF 250V, or something like that would be imprintedright on the body. It would also have marks pointing to the negative end of the capacitor.For more information about this CLICK HERE.

Start here for the smaller non-polarised and old type capacitors!

It's mostly the smaller caps have two or three numbers printed on them, some withone or two letters added to that value. Take a look at the table below.

As you can see it all looks very simple.If a capacitor is marked like this 105, itjust means 10+5zeros = 10 + 00000 =1,000,000pF = 1000 nF = 1 µF. Andthat's exactly the way you write it too.Value is always in pF (PicoFarads). Theletters added to the value is the toleranceand in some cases a second letter is thetemperature coefficient mostly only usedin military applications, or industrial

components.

So, for example, it you have a ceramic capacitor with 474J printed on it: 47+4zeros =470000 = 470,000pF, J=5% tolerance. (470,000pF = 470nF = 0.47µF) The only major

12/9/2009 Capacitor decode page

http://www.wjoe.com/capacitorinfo2.htm 1/4

thing to remember here is to move the decimal point back six place for (uf) and three for(nf). Below in table A, is a simple version for direct conversions to make it easier for you.

TABLE A

coded-decipher-value(pf)-value(nf)-value(uf)......coded-decipher-value(pf)-value(nf)-value(uf)

102 10+00 =1,000pf 1nf .001uf 333 33+000 33,000pf 33nf 0.033uf

103 10+000 =10,000pf 10nf .01uf 334 33+0000 330,000pf 330nf 0.33uf

104 10+0000 =100,000pf 100nf .1uf 472 47+00 4,700pf 4.7nf 0.0047uf

222 22+00 =2,200pf 2.2nf .0022uf 473 47+000 47000pf 47nf 0.047uf

223 22+000 =22,000pf 22nf .022uf 502 50+00 5,000 5nf 0.005uf

224 22+0000 220,000pf 220nf .22uf 503 50+000 50,000pf 50nf 0.05uf

332 33+00 3300pf 3.3nf .0033uf 504 50+0000 500,000pf 500nf 0.5uf

Other capacitors may just have 0.1 or 0.01 printed on them. If so, this representsthe value in µF. Thus 0.1 means just 0.1 µF. If you want this value in nanoFarads (nf) justmove the decimal three places to the right which makes it 100nF capacitor. Some caps willhave a value then a letter. For example .068K, in this case its a .068uf 10% capacitor. Again

just take a look at FIG 2.

The chart below is a simple conversion chart. It will help you understand how we convertuf to pf and nf.

Converting uf-nf-pf

microFarads (µF) nanoFarads (nF) picoFarads (pF)0.000001µF = 0.001nF = 1pF0.00001µF = 0.01nF = 10pF0.0001µF = 0.1nF = 100pF0.001µF = 1nF = 1000pF0.01µF = 10nF = 10,000pF0.1µF = 100nF = 100,000pF1µF = 1000nF = 1,000,000pF10µF = 10,000nF = 10,000,000pF100µF = 100,000nF = 100,000,000pF

Decoding the Old CapacitorsThis chart will help figure out those codes on the Mica molded type capacitors. However

they rearly go bad. I don't think I ever found a bad one myself. Keep in mind this translatesthem to pf or MMF. Don't worry they both mean the same thing. This example below

would translate to 47pf, or 47MMF.



In the picture below you will see two of the most common types of mark ups. In the toppicture the 1st digit can also be silver or black. This is done so you know the proper

orientation before you decipher the value. In the lower picture the two N/A positions canbe blank (no color added).

Plastic or bakelite round capacitors (bumble bee)

By this time you should realize the color code is pretty universal. Decoding may changefrom device to device. These read a lot like resistors. Keep in mind, like before this

decodes to MMF and is equal to PF.

I find most of these in televisions and amplifiers. Sometimes in foreign radios. However theformat is always the same. Other round plastic or bakelite capacitors may have the value

printed right on the body. We have all seen these. There is no decoding them. Some have awhite band on one end, and like these that defines the negative or outside foil connection.

Well that's it. I want to keep it simple and informative. I hope you found it to be both. Nowyou can use this guide to insure you install your caps correctly. Keep in mind this coves



only some capacitors. Since I specialize in antique radios I stuck with the most commontypes.

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09/07/09



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