Connect with us

Capacitor rated voltage question.

Discussion in 'General Electronics Discussion' started by nati levia, Apr 2, 2018.

Scroll to continue with content
  1. nati levia

    nati levia

    13
    1
    Mar 22, 2018
    Hey guys and girls (maybe).
    I need some help... I have 2 of the same capacitors but the voltage is different, I have a 10000μf 10v and a 10000μf 16v.
    Both of them are charged to 10v, The question: will the 16v cap stay at 10000μf even if the rated voltage is lower?
     
  2. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    Yes it will. Some capacitors have what's called voltage coefficient which means their value changes with applied voltage but that is normally ceramics. That is a ceramic capacitor will have its rated capacitance at its rated voltage.
    Thanks
    Adam
     
  3. nati levia

    nati levia

    13
    1
    Mar 22, 2018
    Thanks adam you saved me from trying to see if its true or not and a lot of explosions.
     
    Arouse1973 likes this.
  4. AnalogKid

    AnalogKid

    2,350
    658
    Jun 10, 2015
    An overvoltage of putting 16 V on a cap rated for 10 V probably will not explode. It will shorten its life span. The rule of thumb for most electronic components is to run them at 50% of their ratings. So keep the 10 V cap under 5 or 6 volts, a 60 V transistor at 30 V or less, etc. The increase in long term reliability is very large.

    ak
     
  5. davenn

    davenn Moderator

    13,553
    1,852
    Sep 5, 2009
    never heard of that before, you have reference for that please ?

    that would pretty much wreck every RF circuit ever built as nothing would tune correctly
    and I have built enough RF circuits that do tune properly when using the stated capacitance regardless of the rated voltage

    Dave
     
    Bluejets likes this.
  6. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    davenn and hevans1944 like this.
  7. hevans1944

    hevans1944 Hop - AC8NS

    4,456
    2,073
    Jun 21, 2012
    It would certainly be inappropriate for tuned RF circuits to use multi-layer ceramic capacitors (MLCC), which have a huge voltage coefficient of capacitance, as resonating elements. I have always used ceramic capacitors for high-frequency by-pass applications, often placing them in parallel with electrolytic capacitors that provide low-frequency by-pass functions. All the RF circuits I have ever "played" with used either air-variable or slug-tuned single-layer ceramic capacitors as trimmers. If I needed larger values of fixed capacitance for tuning purposes, I used fixed capacitors with mica dielectrics.

    I suppose there are paper and plastic dielectric capacitors with sufficient stability, but IIRC the available capacitance values are generally too large for most tuned RF applications... at least above one megahertz or so. I have used these capacitors for tuned audio oscillator and audio filter circuits without problems. I may have used ceramic caps for purposes other than high-frequency by-passing of power supply rails, but I think of that as their main use.
     
    davenn likes this.
  8. davenn

    davenn Moderator

    13,553
    1,852
    Sep 5, 2009
    LOL ..... Im at the other end of the RF spectrum, particularly 1GHz and up your air variables and slug tuned caps are way too big
     
    hevans1944 likes this.
  9. hevans1944

    hevans1944 Hop - AC8NS

    4,456
    2,073
    Jun 21, 2012
    Woah! Don't youse guys mix down all that giggle-hertz stuff to real RF wavelengths so your intermediate frequency amplifiers can play? IIRC, my size components can still play a role there. Pretty soon now, all radios will be direct conversion and software defined, so very few discrete components required. Might still need antennas though, so definitely room for amateur radio experimentation. Hmmm. I wonder how a ten meter diameter MLCC parabolic dish would radiate for EME communications... might not even need a feed-horn. Whoops! Woo-woo stuff there.:p
     
    Arouse1973 and davenn like this.
  10. davenn

    davenn Moderator

    13,553
    1,852
    Sep 5, 2009

    hahaha .... anything below 1GHz is DC, just ask any fellow amateur who knows me personally :)
     
    hevans1944 and Arouse1973 like this.
  11. hevans1944

    hevans1944 Hop - AC8NS

    4,456
    2,073
    Jun 21, 2012
    Pretty much agree. Just look at my vanity website to find electrical engineering services advertised as DC to Light™. Anything between one gigahertz and a few terrahertz is just a stepping stone. Lately, almost all the interesting stuff is taking place at infrared wavelengths. At one time, the FCC allocated every wavelength shorter than a certain amount (I forget what it was) to amateur radio service, but this "right" has slowly eroded as the great unwashed discovered the joys of shortwave. Not sure what the law is in Australia.
     
    davenn likes this.
  12. dante_clericuzzio

    dante_clericuzzio

    33
    2
    Mar 28, 2016
    Definitely yes
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-