Capacitor questions

[Gearhead]

Questions for you electronic tech geek types. I'm installing a cylindrical electrolytic capacitor for noise suppression, from the hot lead to ground. The cap, from Radio Shack, has one end where the lead comes out of a plastic insulating disc, and the other end is all metal with the lead coming out. There is an arrow on the body pointing from the plastic end to the metal end.

1. Is there polarity on the cap? Which end goes to hot, and which to ground?
   
2. What would happen if it was installed backward?
   

Thanks,

Jeremy

[GeorgeS]

As rule of thumb, if its an automotive type Noise suppressioin capacitor, should be marked + goes to 12V other end goes to ground.

 

HOwever, there is another type, called FEED Thru. Voltage goes in one end and out the other end, Then the Case,would be mounted to a ground with the bolt.

 

 

OK, REPLey with the Radio Shack Part number, I will check on their site, just to be sure !!!

 

George

[Monty]

If you put a capacitor in backwards, it will blow up on you. I used to pull that trick on people in the lab at electronics school. They would go to the bathroom, and I would turn it around while they were gone...lol...priceless.

[wes0778]

Back in my younger days at the motorcycle/outboard shop we'd charge all the "condensors" in the parts bins using the coil tester. The boss got to where he would pull the point sets, but would absolutely NOT pull the condensors.

[Gearhead]

OK, thanks. That's kinda what I figured. I just envision a cap as two plates and an air gap, simplistic, I know. I had no idea it had polarity. I did indeed install one backward and hooked it up. I was still sitting right there after a few seconds when I heard it boiling / gurgling and I yanked it off the connection. Didn't actually get to the blowing up stage. Now I gotta buy new caps.

 

I showed a guy at work and he showed me the markings, which to me were not obvious. However, it makes sense that the "plastic disc" end goes to hot while the "case ground" end goes to ground.

 

Jeremy