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Capacitor Ident — Parallax Forums

Capacitor Ident

ZetsuZetsu Posts: 186
edited 2012-12-10 17:15 in General Discussion
Say I have some Ceramic-Disk Capacitors, and the only markings on them are :
Y5U
104m

I know the 10 ( with 4 trailing zeros in picos ) .01uF cap.

But how do I determine what its max voltage rating is ?

Comments

  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-12-09 09:58
    Interesting problem. You could just buy some that are packaged with the voltage rating, but that would be a bit silly.

    I believe that 104 is going to be by-pass capacitors for your Propeller at 5 or 3.3 volts, right. I would not worry about it. Ceramic capacitors are usually rated way above that.

    Size generally indicates the capacitor will handle more voltage. But aside from the tiny super-capacitors, just about everything is made for more than 5 volts.

    Googling around, I found something that may indicate the Y5U is a ceramic capacitor product line with a 25v or 50v rating. And the m indicates 20% variation.
  • ZetsuZetsu Posts: 186
    edited 2012-12-09 10:06
    Loopy Byteloose wrote: »
    Interesting problem. You could just buy some that are packaged with the voltage rating, but that would be a bit silly.

    I believe that 104 is going to be by-pass capacitors for your Propeller at 5 or 3.3 volts, right. I would not worry about it. Ceramic capacitors are usually rated way above that.

    Size generally indicates the capacitor will handle more voltage. But aside from the tiny super-capacitors, just about everything is made for more than 5 volts.

    Googling around, I found something that may indicate the Y5U is a ceramic capacitor product line with a 25v or 50v rating.

    Thank you,
    Thats' Kind of what I figured. Like resistors you really don't know the watt rating, just guess by the size..
    Thanks again. :)
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-12-09 10:13
    I looked a bit further and checked Mouser and Digikey. It may only be 16v, but that is still plenty.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-12-09 10:13
    "104" is 0.1 uF (10 * 104 pF). "Y5U" is the type of dialectric used between the "plates." You can learn about the dielectric codes here:

    The voltage rating is a separate spec entirely and is not typically indicated on the package of ceramic caps (probably due to a lack of room for it).

    -Phil
  • ZetsuZetsu Posts: 186
    edited 2012-12-09 10:35
    Phil Pilgrim (PhiPi) wrote: »
    "104" is 0.1 uF (10 * 104 pF). "Y5U" is the type of dialectric used between the "plates." You can learn about the dielectric codes here:
    The voltage rating is a separate spec entirely and is not typically indicated on the package of ceramic caps (probably due to a lack of room for it).


    -Phil

    So when You open up a bin with a bunch of random caps in it ;x What do you normally do, Hook one up to a Power supply and keep stepping up voltage tell you pop it ( then u know the volt rating ) ? I kind of do this with random leds when I dont know there voltage or
    current specs I just hook them up to my psu and step up voltage, tell the Led seems to be in its Operating range look at current I am supplying and then calculate My Resister, and Supply voltage based off that...
    I am still very Green when It comes to actual electronics.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-12-09 22:29
    What you are talking about is 'destructive testing' and it certainly is one way to determine a voltage rating if you have several available with spares. The only other reliable way of determining the voltage rating is to buy products from a source that gives you the information and is considered reliable - Digikey, Mouser, etc.

    Radio Shack often buys in bulk and sometimes doesn't label complete information as the people doing the packaging of components may not know what is considered complete information.

    I try not to deal of junk bins and buy only stuff that has all the information. But I think we all end up with some extra ceramic caps that have no clear voltage rating.
  • GadgetmanGadgetman Posts: 2,436
    edited 2012-12-10 00:18
    Destructive testing isn't all that useful.

    Sure, you find a voltage that enables the component to let out the magic blue smoke, but that may be way higher han the component's rated max voltage.
    Another component of the same make/model/whatever may send smoke signals at half that voltage, or maybe at 50% higher...
    And the function may be 'erratic' for quite a while before that.
    Or they may simply fail after a few months of being used outside of specs.
  • LawsonLawson Posts: 870
    edited 2012-12-10 08:33
    I'm pretty sure Y5U is one of the high dialectic constant capacitor ceramics. These are often a bit piezoelectric, feroelectric, and non-linear. The non-linear bit is the most useful, as the capacitance of the capacitor depends on the DC bias voltage. I expect you could estimate the voltage rating by graphing the capacitance vs DC bias for the unknown capacitor and some know Y5U capacitors. (capacitor data sheets sometimes have this graph)

    Lawson
  • ZetsuZetsu Posts: 186
    edited 2012-12-10 08:50
    Loopy Byteloose wrote: »
    What you are talking about is 'destructive testing' and it certainly is one way to determine a voltage rating if you have several available with spares. The only other reliable way of determining the voltage rating is to buy products from a source that gives you the information and is considered reliable - Digikey, Mouser, etc.

    Radio Shack often buys in bulk and sometimes doesn't label complete information as the people doing the packaging of components may not know what is considered complete information.

    I try not to deal of junk bins and buy only stuff that has all the information. But I think we all end up with some extra ceramic caps that have no clear voltage rating.

    So buying 1000's of ceramic caps and randomly throwing them into bins is not a good idea ;x (I do this often with resistors) Guess Ill try to organize them via voltage rating somehow....
  • ZetsuZetsu Posts: 186
    edited 2012-12-10 08:51
    Lawson wrote: »
    I'm pretty sure Y5U is one of the high dialectic constant capacitor ceramics. These are often a bit piezoelectric, feroelectric, and non-linear. The non-linear bit is the most useful, as the capacitance of the capacitor depends on the DC bias voltage. I expect you could estimate the voltage rating by graphing the capacitance vs DC bias for the unknown capacitor and some know Y5U capacitors. (capacitor data sheets sometimes have this graph)

    Lawson

    Thanks for the suggestion :)
  • Mark_TMark_T Posts: 1,981
    edited 2012-12-10 17:15
    Lawson wrote: »
    I'm pretty sure Y5U is one of the high dialectic constant capacitor ceramics. These are often a bit piezoelectric, feroelectric, and non-linear.
    Lawson

    The family of barium-titanate, lead-titanate and lead-zirconium-titanate ceramics are the principal ferroelectrics - being the electric equivalent of ferromagnetic, and
    thus have _very_ high dielectric constants, non-linear reponse, hysteresis, high losses and furthermore change shape in response to the applied field (as the crystal unit cell is
    distorted in the direction of the polarization). Thus all high-value ceramic capacitors can be expected to be "microphonic" (and are not a good choice for handling low
    amplitude signals! Though fine for decoupling). Nice description of ferroelectricity on wikipedia BTW.

    For lower value ceramics the dielectric need not be ferroelectric, and these are usually much more accurate / low-loss / stable (for instance values in the sub 100pF range
    are typically like this unless extremely high voltage).
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