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Tantalum capacitor marking

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2007-2009 » Archive through 06 November, 2008 » Tantalum capacitor marking « Previous Next »

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echase
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Username: echase

Post Number: 146
Registered: 07-2007

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Posted on Monday, 13 October, 2008 - 01:48 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I have an axial leaded capacitor whose only polarity marking is a long thin black line lined up with one lead. I initially assumed this was a negative marking, being black and like a '-', but the capacitor exhibited high leakage when inserted this way around. Swapping it around cured this.

I see that many tantalums have a + sign and an 'L' shaped black line as the positive marking. I now assume my line is a shortform for this marking. Am I right?

Will 1 hour of running backwards at about 1/3 max voltage have damaged this capacitor?
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stylers
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Username: stylers

Post Number: 144
Registered: 04-2005

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Posted on Monday, 13 October, 2008 - 07:50 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I don't think i have ever seen a tantalum cap with negative marking, there is always a positive next to the stripe. sometimes there are tiny positive symbols within the black line. Not sure if it would have damaged it, but I wouldn't trust it if it were across a supply rail, I have seen a few explode while powering up supply rails to find a short..
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echase
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Username: echase

Post Number: 148
Registered: 07-2007

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Posted on Monday, 13 October, 2008 - 11:03 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

In this case it's got a >1000 ohm resistor to rail so current is small.

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