Capacitor ID

Discussion in 'General Electronics Chat' started by Eric007, Feb 5, 2012.

  1. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    I have a cap here but I'm not too sure about its value...
    It written 22K63 on it but can't really see the sign before that '22K63' but it looks like a 'p' do you know what it is?

    Another one is written '2.2K4001' ????

    Guess, there's no instrument to measure capacitor, huh?

    Thanks!
     
    Last edited: Feb 5, 2012
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Can you post a picture of the capacitor?

    Bertus
     
  3. holnis

    Member

    Nov 25, 2011
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    I'm giving an educated guess here: why don't you unsolder it and check out the other side, but I'd say it will be a 22 µF at 63 V DC. (hence 22k63).

    Other than that I'm pretty certain that it's an aluminium foil Electrolytic (I'm sure I'll be corrected here if I'm wrong).
     
  4. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I disagree. I would expect 22 pF, 63 volts. The K is probably tolerance, and means ±10%. However, as Bertus suggested, a picture would be very helpful. Physical size would give a good idea of the capacitance, whether it would be in μF or pF.

    Regards,
    Der Strom
     
  5. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    I've attached the cap pictures...sorry for the quality!

    Actually, I needed a 0.22uF and a 2.2nF in order to breadboard the circuit provided by Audioguru on my thread 'mic and oscilloscope'

    Those two caps are the one the seller gave when I asked for these values above but I want to confirm with you coz the guy is new in that shop and it seemed to me like the guy was not really sure about the values ( well maybe that was just a false impression)!

    Thanks!
     
    Last edited: Feb 5, 2012
  6. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    u22 = 0.22uF = 220nF 63V
    2.2 = 2.2nF
     
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  7. Audioguru

    New Member

    Dec 20, 2007
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    The blue capacitor is a metallized plastic film type. It is marked μ22k63 which is 0.22μF (220nF) 10% 63V. The "μ" symbol replaces the decimal point.

    Your camera is too blurry for us to read the orange capacitor and we don't know its size.
    It might be 2.2μF.

    Your circuit uses a 25k resistor feeding a 2.2nF capacitor to ground as a lowpass filter. 25k is not a standard value so it should be 27k.
    Instead you can use a 2.7k resistor feeding a 22nF capacitor to ground to make the same filter.

    The filter chops off all high frequencies which are the important consonant sounds of speech. Then speech sounds muffled and unintelligible vowels only. High frequency consonant sounds in speech are S, SH, T, TH, F, and many more. Without consonants then speech becomes hard to understand and confusing (Are my feet are wearing fox or are my feet wearing socks?) (When I come home I wipe my teep on a map on the torch, or I wipe my feet on a mat on the porch?).
    Pole, bole, coal, dole, foal, goal, toll, hole, yo, roll, colt, sole, dolt, sold, bolt, vole, gold, shoal, and troll all share the same vowel sound, only differing in the consonants with which it is coupled, but the difference can drastically change the meaning of a sentence.
    So why are you chopping off the important high frequency consonant sounds in speech?
     
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  8. Audioguru

    New Member

    Dec 20, 2007
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    Capacitor testers are available.
    My multimeter measures the usual volts, amps and resistance and also measures diodes, LEDs, frequency and capacitance.
     
  9. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I have a $35 multimeter that measures all those too, as well as temperature, duty cycle, has a hold, hi/lo, and various other functions. It is a very worthy investment, considering the next cheapest I found was about $80.
     
  10. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    OK! Actually I'm doing this because of the following sentenses I read somewhere:

    - typical frequencies for human voice are on the order of 100Hz to 2Khz...
    - ...most important frequency content in words are within the first 2Khz as this usually contains the 1st and 2nd speech formants....

    So I'm working based on those assumptions! I don't know if I should call it 'assumptions'...that's why my frequencies of interrest are ~150Hz to ~2khz...
    And in my speech recognition application I would sample the signal at 4KHz...and I would like to recognize words such as 'on' 'off' 'go' 'stop' 'reverse' 'one' 'two' 'right' 'left' etc....

    I'm Happy that you've raised that issue...So what is your suggestion for the low pass filter?

    Regards,
    Eric
     
    Last edited: Feb 5, 2012
  11. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    I have a M830BH Digital Multimeter! Can it measure capacitors?
    I gave the multimeter number so you won't ask for a picture...

    Thanks again!
     
  12. Audioguru

    New Member

    Dec 20, 2007
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    Google never heard of your multimeter and neither did I since it does not have a manufacturer's name.

    The VOWELS of speech reach to only 2kHz. That is humming, burps, farts, grunts and groans but not speech. About 25% of speech is consonant sounds that reach up to about 14kHz.

    BUT, there are some languages without consonants. Maybe they talk in Morse code.
     
  13. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I'm not able to find that meter on a google search, but you should be able to tell just by looking at it. Does it say it measures capacitance? Read the manual! :p
     
  14. bertus

    Administrator

    Apr 5, 2008
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  15. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    LOL...Bertus has a better google than you guys...

    Yes Bertus my multimeter looks like the ones in your links...so, like you said, can't measure capacitors!

    Thanks!
     
  16. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    Ok! On Mars we also speak english...lol and I wrote the kind of words I would like to play aroung with...so do you think I ll be ok with that setup or...

    Thanks again!
     
  17. Audioguru

    New Member

    Dec 20, 2007
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    Without high audio frequencies that make consonants in speech, then "off" will sound like "au" the same as the first part of "on". It might be confusing.
    "stop" will sound like "op" which might be OK or might be confused with "on" and "off".
    "two" will sound like like an owl, "oo".
    "Right" will sound like "ri" and "left" will sound like "le" which sound different so should be recognized.

    Try using no lowpass filter so that all speech sounds are heard by the voice recognition system.

    Only 4khz for the sampling frequency? Burps, farts, grunts and groans will be detected, not speech.
     
  18. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    Actually the sampling frequency must be at least two times the highest frequency of interrest 'Nyquist theorem' so I chose 4Khz as I was considering 2000Hz as my highest frequency of interrest...but now that you bring all this..will probably have to change...

    In my system, I'm using several digital bandpass filters from 150Hz to ~2000Hz, each bandpass filter interval is 250Hz so it makes 7 filters...

    Ok! So what range of frequencies should I be interrested in for common words like the ones we've mentioned? Or if I can put that differently what sampling frequency you would prefer to work with?

    Thanks!
     
    Last edited: Feb 5, 2012
  19. Audioguru

    New Member

    Dec 20, 2007
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    I heard a telephone system that was sampled at 4kHz and 8kHz. They both sounded horrible.
    Why do you think that CDs are sampled at 44kHz?
     
  20. Eric007

    Thread Starter Senior Member

    Aug 5, 2011
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    Ok! But what actually trying to do is: First, I'm going to pre record a few words on my MCU then I going to try to recognise words by speaking words on the mic and based on the recognised word...there will be appropriate actions!

    So I'm not going to be listening to words...
     
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