Capacitor voltage tolorance without a label

Discussion in 'General Electronics Chat' started by l0vot, May 16, 2015.

  1. l0vot

    Thread Starter Member

    Apr 29, 2013
    30
    0
    I have come across an Aerovox mica condenser, the label that was printed on the side is too damaged to read, my LC meter claims it's a 2.727nF cap, which is quite small for a cap that weighs a little more than a pound. Would there be any way to find the voltage tolerance of the cap without destroying it?
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,362
    No one labels a capacitor as 2.727nF.
    What exactly does it say on the package? A photo would help.
    A lot of capacitors are 20% tolerance.
    Voltage? Give yourself 50% margin, i.e. use a 50V rated capacitor in a 30V circuit.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,550
    2,374
    If small value and weighs > 1Lb then it could be a 20kv rating as used in TX applications etc.
    In any event it would be special purpose.
    Max.
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    If a 2.7nF capacitor weighs that much - I'm kinda thinking you'll be putting yourself in danger before you get anywhere near the capacitor's breakdown voltage.
     
  5. l0vot

    Thread Starter Member

    Apr 29, 2013
    30
    0
    Thank you MaxHeadRoom and ian field, that should mean it would make a good cap to use for high voltage, high power RF applications. I still would like to know if there is a way to find the max voltage of a cap without breaking it, but that probably isn't a thing that can be done cheaply, if at all.
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    Nope. It's rather like testing a fuse to determine its current rating. It's a destructive test.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Leakage would rise just before actual breakdown - but not in any sense anything like an electrolytic. The leakage would rise a very tiny amount with an extremely narrow margin for detection.

    Mica capacitors were always the first choice in most RF applications, but there's no such thing as a perfect capacitor - it will get hot at RF as you get near its limits.

    This may be your best guide to how far you can stress it.
     
Loading...