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Parts abuse...


Deang

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...by the resident rookie.

Working at my bench last night and managed to knock about a half dozen of my caps to the floor. The floor is in my basement, and has just tile over cement.

The nice polypro caps bounced pretty good -- with a nice smacking sound.

Uh...think I broke anything?

What's "in" a cap anyways?

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It is unlikely you broke anything. Sites such as http://www.howstuffworks.com will usually have decent explanations as to how those things work.

Essentially a capacitor consists of 2 conductive elements separated by a dielectric which is a substance that allows AC to flow relatively unimpeded but will allow DC to flow only in one direction. There is obviously one hello of a lot more to it than that but those are the raw basics.

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Yes, that's a great site. That's where I found the inductor calculator and the information I needed to roll my own.

I guess if I'm really paranoid, I can put the 'ole ohm meter on the leads -- and if everythings O.K. -- I should get zero, right? Any resistance would mean a short?

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Safety Warning:(especially if we are talking about power supply filter capacitors)!

First make sure the cap you are testing has been discharged!! This is important as:

1.) You cannot get an accurate indication of a capacitor's condition with an ohmeter if the cap has a charge on it.

2.) If the cap has a highish charge on it you could fry your meter.

3.) If the cap has a really high charge on it you could fry your recliner's raison d'etre.

"I can put the 'ole ohm meter on the leads -- and if everythings O.K. -- I should get zero, right? Any resistance would mean a short? "

Actually NO!

The ohmeter works by placing a DC voltage across the device and the device's resistance or continuity,(lack of resistance) is measured and expressed in ohms. A capacitor is designed to prohibit or at least greatly inhibit the flow of DC current.

What you will likely see is that the needle will make a sharp tick toward 0 ohms and then depending on the capacitance rating of the cap you should see a relatively rapid increase in resistance. A capacitor will actually conduct DC until it has taken a certain degree of charge.

If the needle goes to 0 ohms and stays there THEN you have a shorted cap.

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Don't be a big baby! Charge the puppy up and give it a quick tap with a finger.

For me:

1.) broken lamp, 120 volts from my elbow to pinkie, horribley painful.

2.) Fixing a Vivitar 283 and touched the cap (like 3" X 1.5", 100,000u), burned me, cried.

3.) in England, I had a male to male cord for a transformer. I accidently unpluged the end that WASN'T in the wall, and burned my thumb and screamed like a 3 year old girl. 240 volts, didn't blow a fuse even.

It's wierd. I am 17 and have never been to the hospital or doctor because of an accident (or anything like it), the electricity gets the best of me. But, I work with TONS of electronics (like wiring, soldering, etc.) The first one wasn't my fault, and the other two were my "learn the hard way" for low and high voltage, so, I should be all done with electricity!!!

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Ditto on the animated avatars. Hey, you guys make web pages and should know better; there is nothing more annoying then a fast repeating, idiotic animation, a definite NO GO on the web. It is distracting and makes reading the text, the most important thing in a forum, all that harder. This new BBS has enough problems as it is.

ps- I sure wish we could turn the signature OFF and ON when we post. Having it show up EVERY time is painful, especially if you post multiple times in a thread.

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