This is my first project using tantulum capacitors. I cannot tell from the markings what the polarity is.
I see a "+" that is halfway between the leads (maybe slightly nearer the left lead) and there is a bold upside down "L" to the right of that which is still between the leads but now slightly nearer the right lead.
Which is lead is which please?
I cannot tell from this distance. The devices must be misprinted if the polarity indicator is ambiguous. I would look at the collection you have, (of the same make and type) and see whether some of them have a less ambiguous indication. Then use that polarity for all of the similar set.
Be sure to stand back or wear goggles when you first apply power. Backwards tantalum caps can spew molten blobs of tantalum in a random direction. You don't want to rely on the blink reflex to limit the damage to merely superficial scars.
You could measure leakage with a cap in series with a large resistor, biasing the string at the rated voltage. If the cap is backwards, it will probably leak a lot more than when properly biased. This can be done without the danger of red hot streamers mentioned above, if the resistor is at least a few K Ohms.
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I have 19 of these tantalums and some are the same and the rest have the "+" smack bang in the middle and the inverted "L" above the right leg. What does the inverted L mean? Is it "-ve" or is it meant to point to where the "+" lead is?
I cannot test these at the rated voltage as I do not have a 35V supply. Any ideas anyone?
Sad so say that sometimes tantalum capacitors get printed with the text off-center, and therefore you get this ambiguous marking occasionally. Tantalums do NOT like being connected backward, so I recommend trying to attach it to a DC power supply at its rated voltage. Mark which way you've connected it; and if it blows up, then you know that's the wrong way to do it. Yes, one must be sacrificed for the good of the rest.
Try this (at your own risk):
Connect two to a power supply. Connect them in parallel, but one must be reversed from the other). Note their hookup (i.e., their polarity with respect to the polarity of the applied voltage). Anything up to the rated voltage is okay.
Put the two caps in a protective enclosure (like a strong box). Wear eye and ear protection.
Turn on the supply. The one that either blows up, or gets hot (check after you've turned off the power) is the one that was hooked up incorrectly.
Throw out the one that got hot (or blew up).
Bob
Thank you everyone for your input. I went with gut instinct and connected one of these critters to 20VDC and stood far back. I had the positive going to the right leg under the inverted "L" or bar sign, and it didn't explode or get hot.
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