Your Source for DIY Pedal PCBs and NostalgiTone! GuitarPCB Forum GuitarPCB Build Support 1uf electrolytic polarity if board outline is film box

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  • #24507
    Anonymous
    Guest

    Hey gang, as always appreciate the help.

    Building a Klon MKC, and C9, 10, and 11 are all 1uf capacitors. I got electrolytic capacitors, which have polarity, but the board is drawn for boxes, which do not.

    Is there a proper polarity for C9, 10, and 11 if using electrolytic? and if so, what is it?

    #24508
    Steve
    Moderator

    I’m not a moderator here but I had the same question regarding a Muff’N build I was doing last week. You can see the discussion here (https://guitarpcb.com/community/topic/muffn-build-question/). Part way down the first page Barry will answer your question.

    Cheers!
    SteveO

    #24512
    Anonymous
    Guest

    The cap orientation is printed on the cap (the side with the line or minus is the negative pole). The negative side on your PCB can be identified by analyzing the schematic, and following the printed PCB paths. Make sure that the polarity is never reversed (i.e. the DC overlay must always be greater than the AC signal amplitude).

    I’d always use film or metallic caps in the signal path (which also do not age as much as electrolytic ones).

     

    #24515
    Anonymous
    Guest

    Thanks Steve and Axelence, it seems the answer is “don’t use electrolytic for 1uf, use film boxes”

    And from Steve’s muff’n post, “don’t use a polarized cap unless you are 100% sure the polarity, lest there be ‘fireworks’, but film caps are better”

    Researching the MoRC (Ross Compressor) board, C2, C3, and C4 are all 1uf, but C2 and C3 are polarized on the board, whereas C4 is a big box.

    So the slightly longer answer is “check the board to determine if 1uf should be electrolytic or a film cap, because it could be both on the same board?”

    #24518
    Steve
    Moderator

    Lincoln, not all PCB’s will be clearly marked as to cap type. But if you look at the schematic for the PCB, it will show exactly what type of cap is needed. (See photo)

     

    #24529
    Anonymous
    Guest

    ooooh solid knowledge gain! Thank you Steve!

    Solved: Check the schematic, and use film if bi-polar!

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