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Forum Index : Microcontroller and PC projects : Is your tantalum cap hot to touch?
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Herry Senior Member  Joined: 31/05/2014 Location: AustraliaPosts: 261 |
Is your Micromite tantalum capacitor hot to touch, while programs fail to load or behave erratically? From the b. obvious aka red face department: This will be because you have it the wrong way round! Polarity does matter!  Senior?! Whatever it says, I'm a complete and utter beginner... |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
D'OH! 
Tant caps, like most polarised caps, distinctly dislike being connected in reverse. It gets fun, when you have students building PSU's, and they accidentally install the filter caps for the regulator in the wrong way around. If the input voltage to the regulator is a reasonable 17v or so, even small electro's make quite impressive amounts of noise and smoke when they blow. 
MLC's(ceramic chip caps) don't care, which is one thing in their favour. Glad you found the error - hopefully things will work much better now.  Smoke makes things work. When the smoke gets out, it stops! |
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bigmik Guru  Joined: 20/06/2011 Location: AustraliaPosts: 2950 |
Hi Herry, I have ***NEVER*** done that before....
Hey why is my Nose so long? 
Your Cap may be damaged now, I would replace it with a new one. Let me know if you need a replacement. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
I concur - any stressed component like this one, needs to be replaced to make sure that it is not the cause of even more stress later on because it has been half-baked. Smoke makes things work. When the smoke gets out, it stops! |
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| hitsware Guru Joined: 23/11/2012 Location: United StatesPosts: 535 |
YES ! ....... especially tantalum ! |
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| srnet Senior Member Joined: 08/08/2014 Location: United KingdomPosts: 164 |
Reversed Tants are quite dangerous, they can explode and eject a red hot particle a considerable distance. Of course being sensible people, I am sure we all use a current limited supply when powering up a board for the first time, and goggles too. $50SAT is Silent but probably still working. For information on LoRa visit http://www.loratracker.uk/ |
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vegipete Guru Joined: 29/01/2013 Location: CanadaPosts: 1132 |
In school we liked to solder capacitors to the end of a mains cable. Surprisingly, we were wise enough to put the capacitor end of the cable on the other side of a door before plugging it in. An electrolitic ends its life with quite a bang... Visit Vegipete's *Mite Library for cool programs. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
We did have one chap wire an LED directly across the mains. Not surprisingly, the LED did not really thank him much for that. srnet is quite right about those tants. A "Normal" electro will tend to "Blow it's top" to releave the internal pressure, so it hisses and smokes, or sometimes blows the top off violently with a loud pop. However, tants are sealed up in that epoxy stuff or whatever it is, and there is no pressure-releave system, so as srnet says, if you are really unlucky, tants CAN actually explode. If you are near them at the time...... ....not good. Please do replace the old one with a new one, observing polarity this time.  Smoke makes things work. When the smoke gets out, it stops! |
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