Capacitor not exploding with over voltage?

[Reldar]

I dissembled a cheap bug zapper racket and noticed the capacitor is rated for 400v. When I removed the capacitor and measured points that connect to the capacitor with a multimeter they measured an output of 930v (input 3.3v).

Maybe I'm being stupid but why is the capacitor not failing even though the voltage is over double the capacitors max rated? Is it because it's not under load or something?
I'm still a newb to electronics.

Thanks.

 

[jackorocko]

I'm still a newb to electronics

they measured an output of 930v

You managed one victory, you're still alive. Seriously, be careful!!!

 

[Harald Kapp]

The capacitor is a type of load for the HV-circuit, so if you re-insert the capacitor the voltage will probably much lower.

As jackorocko said: be careful!

Harald

 

[timothy48342]

"Capacitor not exploding with over voltage?"
Lucky you!!!

When i was a kid I had an electronics kit. One of the experiments in the kit had me wire up a way to get 90V from 4.5V. It was cool. You could feel a tingle in your fingers when you touched it. I can't remember exactly how it was done. Probably some sort of pulse modulated thing. It was very low amperage. Nothing harmful. Safe for kids. Cute demonstration.

I thought what if I store that in a capacitor that has a voltage rating lower than 90V?? It might take a while, but could I destroy the cap?? (That was my goal... destroy a cap.) So I had an electrolytic that came with the kit with a voltage rating lower than 90. I think it was a 3.3uf or 10uf or 100uf. Can't remember.

It took a while to ramp up and I watched the voltage on a meter, but it never got there. I figured out that the meter was saping some of the charge, so I disconnected it and just waited. Eventually it blew and the casing bounced off my forehead. (because... OF COURSE I was leaning over it watching and waiting.) It stung. No big deal. Right?

So I just had to show it to a friend. We watched and waited. We leaned back, because I already knew that thing really was going to fly. It put a hole in the cieling. This was what people call "drywall" or "wallboard." Probably 1/2 inch or so. It went all the way through. The casing probably lies in the ceiling to this day.

Wear eye protection when you should. Don't take chances.

And by the way, I think that device you are playing with has what is called a flyback convertor or flyback transformer. It's the same as what is in a TV or CRT. The ones that have the warning on them that says, "This device contains lethal energy long after the power is off."

Be careful or your be the next nomiee for the Darwin Awards.

-tim

edit:Oh, yeah, and don't think for one sec that beacuse it sources only 3.3V that it can't store huge and lethal energy. :endEdit

 

[selanac]

Hahahah! Wow, funny, but could have been worse.

We ues to do that back in the day when I took Electronics in High School and College. That's how we started out each class each semester to show the danger of Electronics.

We even wired one from our class to a locker. Now days you'd go to jail.

The smart thing would be, Don't do it. How ever just use a little one and stand way back.

Had the Capacitor hit Tim's eye he could be blind today.

 

[davenn]

yes, a large portion of us have probably done some crazy things in days gone bye
when we were young and silly, hopefully the majority live long enough to become old and wise. Of course there are the minority that just become old but are still silly haha

when I was ~ 10 or 11 yrs of age I had an old type telephone with the mechanical electromagnet and 2 bell ringer... they operated at ~ 75 - 90V AC from the phone exchange... I had the wonderful idea that it would really work well across the 240 mains voltage!! ... it did for maybe 10 seconds till the capacitor in the ringer circuit exploded leaving me white faced with fright and mom and dad running from an adjecent room to find the source of the BANG
Needless to say, after a bit of a rahrah from my parents, I didnt try that again and had a healthier respect for mains power.

such as life

Dave

 

[CocaCola]

When I was younger, I experienced what I should have been shielded from My dad what working on something that had a large motor start capacitor, my dad suspected it was defective and went to a local shop, the tech there charged it up and shorted it with a screw driver, as a child my eyes lit up with endless possibilities...

BTW, don't be a fool charged caps can and are really truthfully life threatening, in many cases...