equivalent 22pf ceramic capacitor at radio shack

Discussion in 'The Projects Forum' started by Etronic, Jul 4, 2015.

  1. Etronic

    Thread Starter Active Member

    Oct 7, 2011
    127
    2
    hi all

    I need to find a 22pF capacitor or close as possible equivalent at radio shack. I do not want to order on line for a 40cent part.
    Because I need it now? I couldn't find one.

    This is to be use with 16Mhz crystal. Can someone tell me what I can use instead of the 22pF cap.

    these are the cap I have 22uF, 0.047uF,
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    Sadly there is no substitute for a 22 pF capacitor. Maybe 18 pF or 27 pF, but that is about it. These small capacitors provide the correct load for the crystal and the other ones you mentioned are too large. Swallow hard and order online -- since that is your only alternative. Unless you live near an upcoming hamfest, then you will be in component hog heaven. Maybe you have a friend who will give you a couple.

    BTW:
    0.047 μF = 47,000 pF, and
    22 μF = 22,000,000 pF

    Those are off by too many orders of magnitude.
     
  3. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,790
    828
    Is your Radio Shack still open? Most are closed by now... In the Boston area, I have one retail parts store still available and is not a RS
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,982
    3,713
    You can try this... Gimmick capacitor. Hopefully you have magnet wire instead of strip able sheathed insulated wire as used in the video. Put several in parallel to increase capacitance.

     
  5. crutschow

    Expert

    Mar 14, 2008
    12,977
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    Do you not have any type of electronics part store where you live?
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    If its a real emergency and you can get the right part later - just use a "gimmick" capacitor.

    You just twist 2 short lengths of insulated solid core hookup wire together.

    The temperature coefficient won't be similar to or stable as a ceramic capacitor - but if have needs must...............

    Unless you have an instrument to measure 22pF, you'll just have to do trial & error - give the 2 wires a couple of twists and if it doesn't work, try more or less twists.

    Gimmick capacitors were often used as quick & dirty reaction coupling capacitors way back when regen radios were still popular.

    Possibly the best dielectric you'll find insulating commonly available wire is PTFE, with Kynar not far behind - these were common on wire-wrap boards of very early kit home computer fame.
     
  7. Etronic

    Thread Starter Active Member

    Oct 7, 2011
    127
    2
    THANKS for all suggestions. I may have to order online. Good video GopherT
     
  8. Etronic

    Thread Starter Active Member

    Oct 7, 2011
    127
    2
     
  9. crutschow

    Expert

    Mar 14, 2008
    12,977
    3,221
    So if Radio Shack doesn't have it and you need to order, I suggest you look for an assortment of caps.
    Some places sell kits for lab work consisting of various size and voltage rating capacitors (this for example).
    They are good to have for experimental purposes.
     
  10. Etronic

    Thread Starter Active Member

    Oct 7, 2011
    127
    2
    I FOUND A 0.022uF 50v and a 33pf 300v would both of these work.
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    As the TS originally stated its for use with a 16MHz crystal, I'd hesitate to get the part from Radio Shack, they probably won't even know what temperature coefficient their ceramic caps have.

    16MHz is a common clock frequency, and the loading caps in some scrap item might be very close to the required value. Probably worth digging out any set top boxes that got shoved in a cupboard and look whether anything inside is suitable.

    That ancient XT-turbo hidden in the loft years ago might have the parts. Its almost guaranteed that any decent stash of 8/16 bit cards will somewhere have a 16MHz crystal and the right caps.
     
  12. Papabravo

    Expert

    Feb 24, 2006
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    The 33 pF has a chance (slim) of working.
     
  13. ian field

    Distinguished Member

    Oct 27, 2012
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    Some crystal loading caps are as high as 68pF - I think the 300V disc could be for high voltage pulse applications, the tempco might not even be specified.
     
  14. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    It is true that some crystals are more tolerant than others. The TS was hoping against hope that he could round one up even it it was orders of magnitude off. At least he now makes some attempt to do the right thing.
     
  15. dl324

    Distinguished Member

    Mar 30, 2015
    3,211
    619
    When Radio Shack was still opened, it would take me $5 in gas (round trip) to drive to the closest one. If you want to stock a few for a future project, send me a self addressed stamped envelope and I'll send you a dozen. PM me for my address if interested.

    Offer opened to other members while the first couple hundred last:)

    If you're interested in bartering parts, check out the ecbarter Yahoo Group. You have to join to check the databases, but I'm the moderator and will approve you quickly... To subscribe, send an email to ecbarter-subscribe@yahoogroups.com
     
    Last edited: Jul 6, 2015
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