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Reading Capacitors

H_manH_man Posts: 6
edited 2005-10-12 16:18 in General Discussion
jumpin.gif·I bought a package of assorted disk capacitors and need to know how to read their rating.· They're not the traditional style with three numbers but they're a peculiar style with just one or two numbers and no letter. They look like this:
(1) or (10) or (25)etc.

How do 'I know their rating from these numbers instead of three?


Post Edited (H_man) : 10/10/2005 10:12:40 PM GMT

Comments

  • H_manH_man Posts: 6
    edited 2005-10-10 22:18
    Can someone please help me?
  • NewzedNewzed Posts: 2,503
    edited 2005-10-10 22:21
    I have no idea.· Do you have a multimeter that will read cpacitance?

    If not, send me one of each and I will tell you what the value is.

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    Sid Weaver
    Do you have a Stamp Tester yet?
    http://hometown.aol.com/newzed/index.html

    ·
  • H_manH_man Posts: 6
    edited 2005-10-10 22:25 
    (replace this text with your code)

    What setting should I put the multimeter on? Like what symbol would it be.· I'm new to robotics.· This is for a light sensor on my robot btw.· I'm using a 220ohm resistor, and a CDS photocell to detect light so I need to know the rating of the capacitor so electricity isn't constantly being sent to the photocell.

    Post Edited (H_man) : 10/10/2005 10:39:02 PM GMT
  • NewzedNewzed Posts: 2,503
    edited 2005-10-10 22:43
    If it is anything like mine, it should have a capacitor symbol on the switch selector.

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    Sid Weaver
    Do you have a Stamp Tester yet?
    http://hometown.aol.com/newzed/index.html

    ·
  • H_manH_man Posts: 6
    edited 2005-10-10 23:12
    Ooh, I don't think mine has that... Could the 1 stad for the same thing as 1microfarads which is equivalent to 10,000pictoFarads?
  • NewzedNewzed Posts: 2,503
    edited 2005-10-10 23:15
    I don't think you will find a 1uf cap in a disc.

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    Sid Weaver
    Do you have a Stamp Tester yet?
    http://hometown.aol.com/newzed/index.html

    ·
  • H_manH_man Posts: 6
    edited 2005-10-10 23:19
    I have a 104k disc which is 1uf but it broke so that's why I need a 1uf disc. Maybe it's 0.1uf...
  • japerjaper Posts: 105
    edited 2005-10-11 02:04
    hello

    i bought an assorted cap pack and most are useless in a stamp enviroment
    some of the cermacic disc are actually -|(- so watch the polarity
    also most have a large voltage threshold
    the best way to test other than the above metioned
    RCTime with a good resistor
    i could be off base but ....
    japer
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-10-11 04:46
    Well the last of the 3 digits indicates·powers of 10

    103 is·bigger by 10 that 104.· {This is wrong, see Chris below - It should read 103 is smaller than 104 by 10.}

    If the first two digits are·not 10, then they indicate a fraction of 1.· [noparse][[/noparse]10 actually means 1]

    563 is actually .56 and the 3 indicates the mutipler

    If you don't have three digits, they are tiny, tiny picofarad capacitors.


    So, the real question is where to do you start? Start with the 101 which I believe is .0001 micro farad.

    Get five baggies and put all the third digit 1's together, put all the third digit 2's together, and so on down the line.

    I think they are NON-polarity [noparse][[/noparse]reversible] unless marked clearly. And they are all over 100volts unless marked.

    If this ain't good enough, try Google for Capacitor Code and read someone else's description


    By the way, the Blue resistors (1%) have 4 stripes and the Tan (5%) ones have 3, so the multipler - which is the last stripe - will not be the same color for the same value.

    Can you see why?

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    G. Herzog in Taiwan

    Post Edited (Kramer) : 10/11/2005 4:15:10 PM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-11 14:19
    Actually, 104 is .1uF and 103 is .01uF in most ceramic disc caps I have seen.· =)

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-10-11 15:56
    It really helps to acquire some reference material.
    I tried to do this from memory, but it didn't work.
    I added corrections, deleted mis-information.

    The range is from 106 to 101. 106 is the highest, 101 is the lowest.

    There are three tolerance codes

    J=5%; K=10%; M=20%

    There are three ranges

    PP where 102 equals 1000PF

    nF where 102 equals 1nF

    F·· where 102 equals 0.001F

    ·

    What all this really means is that you should buy a good Capacitance meter and read that.

    Otherwise, you have to be sure that the store marks the package with the correct item.

    ·



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    G. Herzog in Taiwan

    Post Edited (Kramer) : 10/11/2005 4:13:58 PM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-11 16:29
    Sometimes if parts come from a surplus distributor they can be "house marked", which basically means they won't have standard part numbers, and then you would need a meter.· I have seen a numbering scheme similar to what you posted though, so you should be able to find that information.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2005-10-11 18:16
    102,103, 104,473,223,...

    The way that is most easiest for me to remember is that the disk capacitors are always in
    pF(pico-Farad). If there are 3-digits, the last digit is always the number of trailing zero's.
    For example:

    102 = 1000pF = .001uF
    103 = 10000pF = .01uF
    104 = 100000pF = .1uF
    473 = 47000pF = .047uF
    223 = 22000pF = .022uF

    If there is less than 3-digits, then that value is simply the pF value.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-10-12 08:07
    Thanks Beau, I had an off day for my techinical writing skills.
    I don't understand all the extra space in my last post. I tried to delete it.

    I guess you could say 102 equals 10+2zeros in pF, 103 equals 10+3 zeros in pF, and so on to get the Powers right.

    House markings are always a problem, generally you save nothing by buying them in small quatities for hobby use unless it is a 'must have' component that is hard to come by. Also, I alway suspect they are sometimes rejects.

    Anyway, I was wondering one thing.

    Do all two wire devices [noparse][[/noparse]capacitors and LEDs mainly] that require proper Polarity for installation have ONE lead longer that the other?

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    G. Herzog in Taiwan
  • bobledouxbobledoux Posts: 187
    edited 2005-10-12 13:19
    There are lots of simple ways to test for unknown capacitance. One simple way is to wire up a 555 timer chip as an oscillator. Put known resistances into the timing circuit with an unknown capacitance. Read the output on a frequency meter. Calculate the cap value using the 555 timer frequency formula.

    No frequency meter? Wire up the circuit with a 1 meg pot. Insert the unknown cap and adjust the pot until an audio tone is heard. Adjust the pot to a known audio frequency like a tone from a guitar string. Read the pot value and calculate the cap value using the 555 timer formula.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-12 16:18
    Kramer said...(trimmed)
    House markings are always a problem, generally you save nothing by buying them in small quatities for hobby use unless it is a 'must have' component that is hard to come by. Also, I alway suspect they are sometimes rejects.
    House markings are sometimes used to help disguise the values of parts used in products, but are a nightmare when you don't have the data and forget what a part is.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
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