Things that go pooof/pop

[zachtheterrible]

ive heard that electrolytics go bang when they're connected backwards. the new ones have this vent @ the botom.

 

[samcheetah]

yes electrolytics can go BANG when you connect them in reverse. usually larger electrolytic have an X on top of them so that when the cap explodes the can doesnt fly out. actually when you connect it in reverse a chemical reaction occurs that produces hydrogen gas (or some other gas).

 

[Anonymous]

I've never seen a 3mF cap go bang. Not my fault
Manz ... smells real bad.

 

[Evil_Genius]

Popping Caps No Mo

Over 10 years ago, I could get 1000 uF caps that would just EXPLODE!!! Now, designed to go.fffffffffffftssss. How's a young guy gonna get his fun anymore? . OSHA managed to take it all away. But they still stink. Note that the smoke is definitely NOT healthy. Down right noxious

 

[bryan1]

Eh I just acqired a few 1 farad caps from work there rated a 630 volts so I reckon powering them up the wrong way could be a top display.

Just da evil in me comin out :twisted: :twisted: :twisted:

 

[jrz126]

:shock: Those should blow pretty good! try to get a video of it if you can!

 

[samcheetah]

i dont think that the amount of explosion depends on the rated maximum voltage. i think it depends on the capacitance and the physical size of the capacitor. and i think that blowing a 630V capacitor might not be a good idea. i would not recommend playing with that much high voltages. anything bad could happen.

anyway if you still want to try blowing it then do it. and dont forget to upload a couple of snaps of it :lol:

 

[bryan1]

mmmm I made up an electric fence controller that puts out 3.6kilovolts I wonder if that would make it POOOOOOOOOOOOOOOF ????????

 

[Valeo Penitus]

Electrolyte cells create hydrogen and oxygen when a current is applied and how much is created in a time period depends on the voltage.... so yeah with that much voltage you would get a pretty good explosion in a fairly short time i would imagine.

 

[Nigel Goodwin]

Electrolyte cells create hydrogen and oxygen when a current is applied and how much is created in a time period depends on the voltage.... so yeah with that much voltage you would get a pretty good explosion in a fairly short time i would imagine.

But electric fences are only low current, and usually just slow pulses of power - a short pulse every couple of seconds. At least the ones I've ever seen were - except for the one that had 240V mains wired straight to the fence!.

 

[zachtheterrible]

[/quote]
At least the ones I've ever seen were - except for the one that had 240V mains wired straight to the fence!.[/quote]

:shock: :shock: wut was the purpose of that fence? to get the builder in a lawsuit? . . . . . sudden, instant, and even immediate death

 

[Nigel Goodwin]

At least the ones I've ever seen were - except for the one that had 240V mains wired straight to the fence!.[/quote]

:shock: :shock: wut was the purpose of that fence? to get the builder in a lawsuit? . . . . . sudden, instant, and even immediate death[/quote]

It was to keep cows out of a field of kale (I think it's spelt with a 'k') - an evil smelling green plant used for cattle feed. Cows love the stuff!.

This was back in the late 1960's, I was one of a number of kids who had to beat across those fields - basically scaring pheasants out so people could shoot them. We had to very carefully climb under, or over, this 240V live wire in the pouring rain!.

Tough job for very little pay, we got paid 10 shillings for a saturdays work, a friend from school used to do a similar job (but for grouse) and got paid 4 pounds (eight times as much!). If you didn't get electrocuted you were still liable to get shot! :lol:

BTW, 240V isn't "sudden, instant, and even immediate death", I've had a great many 240V shocks - you have to work pretty hard for 240V to kill you, or be really unlucky!. But a number of people are killed every year, but that happens with 110V mains as well.

But having said that, being in soaked clothes, in the pouring rain, is probably "working pretty hard" towards it! :lol:

Kids these days don't know they are born!.

 

[bryan1]

At least the ones I've ever seen were - except for the one that had 240V mains wired straight to the fence!.[/quote]

:shock: :shock: wut was the purpose of that fence? to get the builder in a lawsuit? . . . . . sudden, instant, and even immediate death[/quote]

LOL Zach,
The electric fence controller I made develops 3.6kilovolts but only draws 190milliamps of power off 12 volts. When a human touches it you only get a mild shock but 1 of my mates found out the wrong way when he decided to take a leak on the fence. My wife reckons she heard him scream from over 1/2 a kilometre away. But it was a top laugh...

cheers Bryan1

 

[zachtheterrible]

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HAAAA AHAAAAAAAAAAAAAAA!!!!!!!!!! THAT IS A TOP LAUGH!!

i stil cant imagine y someone would power an electric fence directly off 240v. its not the voltage that kills, its the amperage :shock: .

 

[samcheetah]

its niether the voltage nor the current that matters. its the power (or energy transferred per unit time) that matters.

so no matter what the voltage is the amount of shock will depend on the power transfered to the person and the path followed by the current. and if the heart comes in the electrical path the heart will start fibrilating.

 

[mechie]

Electric Fence ?

Take a peek at ...
**broken link removed**

I remember something a couple of years ago about an electric fence killing several cows when the old mains-powered energiser developed a fault :shock:

 

[Evil_Genius]

Wading In

Hey Guys -
Let's not give people new to electronics any ideas. Yes, it is the power or wattage. Multiply the current by the voltage. That is the formulae for watts. How many watts does it take? That depends where you take it. A flash unit from a disposible camera (!capacitor removed!) generates .1 W but runs up to 300 volts.
Go figure. 300V X ?A = .1W
A great tingle up to the wrist if one hand is used. Two hands does create a hazzard for a child or person with heart problems. But hit the temple with the same unit and you will have a lawsuit on your hands after the victim stops convulsing.

 

[zachtheterrible]

someone told me that, its not the voltage that kills, its the current. dont blame me :lol:

 

[Nigel Goodwin]

someone told me that, its not the voltage that kills, its the current. dont blame me :lol:

It is, a high voltage current limited source (like the 25-30KV in a TV), doesn't have enough current to harm you, and it's why earth leakage trips (GFI's) trip out when a specific current leaking to ground occurs.

However, you need a highish voltage to get a high enough current to flow (simple ohms law) - a 12V car battery can supply 100's of amps, but because it's too low a voltage it's perfectly safe.

 

[bmcculla]

5mA through your heart will kill you (GFI's trip at this current). Dry skin is about 50kOhms - no problem with low voltages. If you peirce the skin or use good medical electrodes the resistance drops to about 500Ohms - allowing you to kill yourself with a small battery.

Speaking of things that go pop - 12V rated Tantalums running at 24V are nice because they run great for a while then when you least expect it shoot out a big jet of flame. 600W supplies coupled with careless multimeter use also work well (my + probe now has a flat melted looking tip instead of a nice point). With the same 600W supply I also managed to remove one of my important PCB signal traces - it was there one minute and the next - POOF - you'd never guess that there used to be a trace there.