Re: Tantalum capacitors have polarity
Last year I bought some small voltage up-converter modules off ebay - up to about 30v in and up to 35v out. They looked much the same as the buck down-converters I had used in several designs - a small can capacitor at each end and the transformer gubbins in the middle. Voltage adjustment was by a multi-turn pot.
So - I set one up in the same way as I did the down-converters. Hooked up 12vdc to the input and put a multimeter on the output with no load . Being lazy I didn't connect the meter permanently - assuming I could twiddle the pot and stop to take readings occasionally.
Quite what went wrong I don't know. While fiddling with the leads to get the meter to show a reading there was a sudden bang and the output capacitor's can shot into the air - ricocheting off my finger. The paper innards were left behind connected to the board. It was fortunate that the can had not hit my face.
My presumption was that the module was capable of producing more than the stated 35 volt maximum output. Both capacitors were marked as "35v". Looking on ebay I found that other suppliers' apparently identical modules were populated with a "50v" output capacitor. Sent the seller a picture of the damage and pointed out the other sellers' difference - immediate full refund.
Biting the hand that feeds IT
