Author Topic: How dangerous are capacitors?  (Read 2919 times)

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Offline jamortTopic starter

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How dangerous are capacitors?
« on: June 25, 2009, 05:42:29 AM »
I just reas a thing that said capacitors will explode if you dont place them right as far as current flow...
I was just wandering how dangerous they can be... Is it anything to worry about?
my english teacher once said, "dont talk about what you dont know in public...."

so I replied the truth, " Exactly why I dont ever talk about English."

Offline Joker94

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Re: How dangerous are capacitors?
« Reply #1 on: June 25, 2009, 06:04:47 AM »
i have aways wondered that. I guess there would be a sign that something was wrong before it blew but you never know

but when you think about it i wouln't worry and infact i don't worry

i think i may try it and see what happens

what sort of capacitor are you refering to, electrolityc would probably be the worst

Offline Admin

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Re: How dangerous are capacitors?
« Reply #2 on: June 25, 2009, 11:35:25 AM »
They explode (in your face) when you apply too much voltage. I've seen it happen.

Offline Metal Slug 2

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Re: How dangerous are capacitors?
« Reply #3 on: June 25, 2009, 02:36:07 PM »
very true, take a look:

[youtube]http://www.youtube.com/watch?v=v5v4_AlDQTo[/youtube]

[youtube]http://www.youtube.com/watch?v=M8nT97CrgcU[/youtube]

[youtube]http://www.youtube.com/watch?v=QXWS2FEps4E[/youtube]

...yea, its something to worry about.  Shorter lead is always negative, longer is positive  (plus the capacitors are always Marked with which side is which).

Offline jamortTopic starter

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Re: How dangerous are capacitors?
« Reply #4 on: June 25, 2009, 02:46:30 PM »
ok... looks like having safety googles on would give rid of most damage? I was just like what? cause I dont remember reading anything about it but doesnt mean i didnt
my english teacher once said, "dont talk about what you dont know in public...."

so I replied the truth, " Exactly why I dont ever talk about English."

Offline Soeren

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Re: How dangerous are capacitors?
« Reply #5 on: June 25, 2009, 03:30:52 PM »
Hi,

I had a 10,000F metal can blow in a PSU right next to me once - sounded like someone had fired a .45 round close to your ear. Luckily I had build it in a steel box, so no harm but the characteristic smell of burnt electrolyte stinking up my lab and a circuit so messy I didn't care to repair - the metal can was torn apart down the full length.
It had been in daily service for some 20 years, so it wasn't a design flaw, but old age I guess.
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Offline Joker94

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Re: How dangerous are capacitors?
« Reply #6 on: June 26, 2009, 02:45:35 AM »
the reason that i said i don't worry is that the voltage that i use for my boards are not high  enough to make it explode

Offline SmAsH

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Re: How dangerous are capacitors?
« Reply #7 on: June 26, 2009, 08:43:38 AM »
just a word of wisdom, always wear protective goggles when turning on a new circuit for the first time.
your eyes are worth the $10 for the goggles...
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Offline Trumpkin

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Re: How dangerous are capacitors?
« Reply #8 on: June 26, 2009, 11:46:48 AM »
Diodes can also explode (yes, EXPLODE), I had a diode that was right next to a capacitor it exploded and at first I thought it was the capacitor that had exploded, but upon further examination it was the diode.
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Offline SmAsH

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Re: How dangerous are capacitors?
« Reply #9 on: June 26, 2009, 03:16:13 PM »
too much voltage? wrong polarity? what?
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Offline kd5kfl

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Re: How dangerous are capacitors?
« Reply #10 on: June 26, 2009, 03:35:58 PM »
You can get a no fooling mushroom cloud from a capacitor. cap was about the size of a large yellow pages. 6 foot high, 2 foot across mushroom cloud

Offline paulstreats

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Re: How dangerous are capacitors?
« Reply #11 on: June 26, 2009, 06:00:43 PM »
If you ever get into building marx generators and pushing the capacitor levels then worry... (the only time ive had a cap explode)

normally there isnt a problem when using them within rated parameters, aspecially these days. things are much safer now than they used to be.Just stick to the rated parameters and younshouldnt have a problem.

As soeren mentioned above, a cap exploded but that was likely to be a device that had seen a LOT of usage...

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Re: How dangerous are capacitors?
« Reply #12 on: June 26, 2009, 08:32:51 PM »
The rule of thumb is rate the capacitor voltage at 2x what you expect to have in the circuit.

And as smash said, always wear goggles when turning on your circuit for the first time. I've seen circuits explode in my friends faces a half dozen times - but luckily not yet for me. Burnt myself on a MOSFET once though, that hurt for a week . . .

If you want to see a pretty explosion, overvoltage an L298 motordriver. Colorful fireworks!

Offline SmAsH

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Re: How dangerous are capacitors?
« Reply #13 on: June 26, 2009, 08:49:19 PM »
Quote
Burnt myself on a MOSFET once though, that hurt for a week . . .
i think i remember this or talking about it last year :P

ive only ever one had a cap explode on me, my friend was sitting next to me and im not sure what he did but it went "James, why is the cap getting bigger?" i didn't actually realize that it was going to explode but luckily we both had glasses on because we were soldering ;D
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Offline galannthegreat

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Re: How dangerous are capacitors?
« Reply #14 on: June 26, 2009, 09:29:45 PM »
I remember once appliying 1 volt to a SMT LED, and then all of a sudden, BOOM! It exploded with a very loud crack and the scorching diode flew up and hit my cheek. That one sure hurt, so watch out for the surface mount LED's too (pretty much all diodes and caps).
Kurt

Offline revhead

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Re: How dangerous are capacitors?
« Reply #15 on: June 27, 2009, 12:49:31 AM »
you can also get electrocuted by capacitors because they store energy similar to a battery even when the power is removed. Before touching a circuit board i always touch the leads from a capacitor with a screw driver to dissipate any energy still stored in the cap. The proof is when you manage to light up an LED for a split second by touching it to the cap!

Offline SmAsH

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Re: How dangerous are capacitors?
« Reply #16 on: June 27, 2009, 01:03:28 AM »
yes, high voltage caps are a nono unless you have discharged them.
you can always find some in old crt monitors. but you wouldn't want to touch an led to one...
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Offline jamortTopic starter

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Re: How dangerous are capacitors?
« Reply #17 on: June 27, 2009, 01:14:40 AM »
yeah.. I heard that tvs and crt monitors can kill you in the process of taken them apart and tinkering around in them because even disconected from power they still have charge... luckily though i think the use of lcd monitors and flatscreens are giving rid of this problem
my english teacher once said, "dont talk about what you dont know in public...."

so I replied the truth, " Exactly why I dont ever talk about English."

Offline SmAsH

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Re: How dangerous are capacitors?
« Reply #18 on: June 27, 2009, 01:28:47 AM »
im using a crt monitor right now... thats not to say plasmas and lcds cant kill you... they may even be worse!
i thinker with old electronics like crts a fair bit, but i always discharge the big caps and wear rubber gloves...
and remember, when working with high power stuff always keep your left hand in your back pocket.
Howdy

 


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