why +ve terminal of electrolytic caps must be connected to +ve of battery?

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dexterdev

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Hi all,
I have a doubt regarding electrolytic capacitor. Why the electrolytic capacitor should be connected to higher DC potential in the circuit. What happens if the opposite happens? Also how electrolytic capacitors must be used where varying voltage comes across it?

-Devanand
 
I don't understand your question, are you asking why electrolytics shouldn't be connected backwards? They are polarized, internally there is an oxide layer that is formed in a similar fashion to the lead oxide layer in a car battery, and in a similar way a reverse-connection will drive the oxides off the plate and can create an internal short.

A capacitor stores a charge, like a reservoir - so when a varying voltage comes across it, it is like the varying height of a river that leads into and out of a lake; the level of the water in the lake will tend to keep the level in the river the same height.
 
dexterdev said:
Hi all,
I have a doubt regarding electrolytic capacitor. Why the electrolytic capacitor should be connected to higher DC potential in the circuit. What happens if the opposite happens?
-Devanand
Click to expand...

its likely to at worse result in a big bang as the capacitor explodes

D
 
I've never really seen an electrolytic cap smoke, they tend to go off like small fireworks when reverse biased at full supply voltage.

One of the fond memories I have as a kid, a friend of mine applied 24V in reverse to a 12V cap. They go off nice =>
 
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Sceadwian said:
One of the fond memories I have as a kid, a friend of mine applied 24V in reverse to a 12V cap. They go off nice =>
Click to expand...

For a second I thought I might be your childhood friend. I did something similar to my friend as a kid, but it was not a reverse voltage but an overvoltage of the correct polarity. So, 24 VDC applied with the correct polarity to a 12 VDC capacitor has the same effect. They go off nice, like a small fireworks. It was a fond memory for me too, but he wasn't too happy that it blew up in his face. That's what happens when two people try to share the same power supply in lab class.
 
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During my evil childhood (I am now an evil adult) I would take small tubular polarized electrolytic caps I salvaged and place them across the switched outlet (for a table lamp) in my sister's bedroom. She would enter her room at night and turn on the wall switch and it was like... 3, 2, 1, BANG! This was fun and amusing till my father found the remains of a cap and damn near killed me. Hell, I thought it was funny as they went off about like a firecracker. Unfortunately my father did not quite see the humor in this.

Ron
 

LOL.

I was fond of doing that kind of thing myself long ago. Electrolytic cap's are lots of fun for the uninformed.

30VDC on a little 16V 100Mf cap the wrong way round was pretty funny back then.

Nothing however beats a Mains Smoothing Cap......inserted the wrong way around....on a SMPS on a TV....made a hole in the roof.....

Hell, it's still funny now after all the years . Almost killed me though

Cheers,
TV Tech
 
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I remember a loud *BANG!* in the shop at Aladdin's Castle. Smoke was coming out of the big wooden coin-op arcade game, my buddy Warren was holding the wall plug looking confused. We took the back door off, inside the game was full of shredded foil and paper confetti - MASSIVE amounts of the stuff, armfulls, stuffed a green trashbag tight with it and we were still picking bits out of the monitor and the coin door an hour later. A beer-can-size filter cap had gone off. Didn't even look possible that all that foil and paper could ever have fit in that aluminum cylinder on the bottom of the game.
 
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