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Tubular Capacitor Polarity

Discussion in 'General Electronics Discussion' started by Wireaddict, Oct 13, 2017.

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  1. Wireaddict

    Wireaddict

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    Oct 13, 2017
    I'm a newbie here but I've been working working with electronics & bending wires for about 60 years. My question is: I have some old tubular capacitors with axial leads from the '50s & '60s in my parts bins that still read good. Typical values are 0.1uF @ 400 WVDC but, unlike electrolytics which have their positive &/or negative terminals marked, these tubular caps only have a band printed on one end but no plus or minus indications. I'd like to recycle some of these caps in places where size isn't important such as power supply noise bypassing but I'd like to know the correct polarity or whether it matters for voltages in the 25 V range (AC & DC). Thanks for the assistance, I'll try to return the favor as time & knowledge permit.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,346
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    Nov 17, 2011
    Welcome to EP.

    These caps do not have a polarity. Teh band indicates the ouside foil. In a power supply the orientation is irrelevant. Within an amplifier some people argue that correct orientation has an effect.
     
    Wireaddict and kellys_eye like this.
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    There orientation can certainly have an effect in a high impedance circuit where there is electrical noise. However this problem was far more prevalent when point to point wiring was used in close proximity to AC (used for heaters of tubes).
     
  4. Wireaddict

    Wireaddict

    17
    2
    Oct 13, 2017
    Thanks for the help!
     
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