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Using Arduino => General Electronics => Topic started by: cjdelphi on Oct 11, 2012, 03:44 pm

Title: LOL - Exploded cap.
Post by: cjdelphi on Oct 11, 2012, 03:44 pm
I have a circuit that powers a 11watt fluro tube from 12v, so i decided to have some fun and ramped it up to 16v, 20v, kept turning to max out this step up voltage regulator and i was starting to hit around 25volts
and BANG!!!!, the input capacitor exploded the whole house heard it, it was a 16v 10uf or pf, not sure, i replaced it with a 100pf 25v cap and cranked up the voltage to 22 volts getting a spark gap of around 6cm :D but anyway whatever happened it knocked out my computer (not even on the same circuit) reset my arduino (Which shared the same battery) something weird happened just before or just after huge amounts of energy for a brief moment was consumed my voltage regulator could not care less it seems must have spiked over 6amps which it was happy with, shame the voltage regulator powering the arduino could say the same, and as for why my computer died (power on, screen off) usb is not connected there's no shared link, it's isolated, but it was enough to make the arduino go spastic and tell me there's a power out (located about 1 meter away).

as for the bang, it's deafening not nice .... but sure was FUN!!!!
Title: Re: LOL - Exploded cap.
Post by: fungus on Oct 11, 2012, 03:58 pm

as for the bang, it's deafening not nice .... but sure was FUN!!!!


Yeah, those things are noisy when they go off.
Title: Re: LOL - Exploded cap.
Post by: dhenry on Oct 11, 2012, 04:54 pm
Exploding caps can easily take out an eye or two.
Title: Re: LOL - Exploded cap.
Post by: BulletMagnet83 on Oct 11, 2012, 06:23 pm
What some of us used to do in college was to get some little 1 or 10uF electrolytics, put them inside a pen casing with the legs hooked up in reverse to a bench supply at full voltage, and use them as cannons to fire diodes across the room. A bit childish to say the least... but nobody died :)
Title: Re: LOL - Exploded cap.
Post by: JoeN on Oct 11, 2012, 06:32 pm
http://www.youtube.com/watch?v=9jDsNe_bmtE

3:40
Title: Re: LOL - Exploded cap.
Post by: cjdelphi on Oct 11, 2012, 06:42 pm
so what happens to all the stored energy? dissipated by heat?
Title: Re: LOL - Exploded cap.
Post by: DVDdoug on Oct 11, 2012, 06:45 pm
Quote
and as for why my computer died (power on, screen off) usb is not connected there's no shared link, it's isolated,
My guess is that the high-voltage arced back throught the power supply into your house-power, causing a power-line spike.
Title: Re: LOL - Exploded cap.
Post by: fungus on Oct 11, 2012, 07:02 pm

Exploding caps can easily take out an eye or two.


I've got a couple of 68000uF caps on the shelf. They look at least 20 years old, maybe more. We used to hold a couple of wires on them to charge them up then melt nails across the screw terminals on the top. Stuff like that. Here's one of them with a couple of normal size components for comparison.

(http://www.artlum.com/pub/68000.jpg)

One day a little 10uF electrolytic exploded quite close to me. The metal case flew across the room fast enough to flatten itself against the opposite wall (which means it must have been going about the speed of a bullet...)

Ever since then I've been too scared to charge the big one.

Title: Re: LOL - Exploded cap.
Post by: fungus on Oct 11, 2012, 07:03 pm

so what happens to all the stored energy? dissipated by heat?


Heat+light+sound. A bit like an electric firecracker.
Title: Re: LOL - Exploded cap.
Post by: JoeN on Oct 12, 2012, 08:31 pm


Exploding caps can easily take out an eye or two.


I've got a couple of 68000uF caps on the shelf. They look at least 20 years old, maybe more. We used to hold a couple of wires on them to charge them up then melt nails across the screw terminals on the top. Stuff like that. Here's one of them with a couple of normal size components for comparison.

(http://www.artlum.com/pub/68000.jpg)

One day a little 10uF electrolytic exploded quite close to me. The metal case flew across the room fast enough to flatten itself against the opposite wall (which means it must have been going about the speed of a bullet...)

Ever since then I've been too scared to charge the big one.


(http://upload.wikimedia.org/wikipedia/commons/7/79/Operation_Upshot-Knothole_-_Badger_001.jpg)
Title: Re: LOL - Exploded cap.
Post by: oric_dan on Oct 13, 2012, 01:04 am
Fun, but not as dangerous as back in the old days, when there were 500V plus
power supplies on TV sets, and the "diodes" were vacuum tube rectifiers, which
tended to croak a lot.

I once saw a rectifier short out, the plate glowed an intense red for a couple of
seconds, then the large METAL-case electrolytic cap [roughly 5" tall and 1.5" in
diameter] exploded, and the can flew up like a rocket and put a dent in the
ceiling.
Title: Re: LOL - Exploded cap.
Post by: BulletMagnet83 on Oct 13, 2012, 04:59 pm
Ahaa, those good ol' pre-1960 murderboxes :D They definitely don't make 'em like they used to.
Title: Re: LOL - Exploded cap.
Post by: jrmcferren on Oct 13, 2012, 07:20 pm
I've had a few electrolytics pop in my time with electronics. First I had a power supply with a shorted pass transistor (linear regulator) and hooked up an old car clock. After trying to get it to work (not thinking of an overvoltage problem) the electrolytic popped. Second incident was with a power inverter. Plugged it in and the cheap capacitor popped immediately. I was lucky that they were enclosed in a device at the time as the first one definitely would have gone flying.
Title: Re: LOL - Exploded cap.
Post by: krupski on Oct 13, 2012, 08:44 pm

I have a circuit that powers a 11watt fluro tube from 12v, so i decided to have some fun and ramped it up to 16v, 20v, kept turning to max out this step up voltage regulator and i was starting to hit around 25volts
and BANG!!!!, the input capacitor exploded the whole house heard it, it was a 16v 10uf or pf, not sure, i replaced it with a 100pf 25v cap and cranked up the voltage to 22 volts getting a spark gap of around 6cm :D but anyway whatever happened it knocked out my computer (not even on the same circuit) reset my arduino (Which shared the same battery) something weird happened just before or just after huge amounts of energy for a brief moment was consumed my voltage regulator could not care less it seems must have spiked over 6amps which it was happy with, shame the voltage regulator powering the arduino could say the same, and as for why my computer died (power on, screen off) usb is not connected there's no shared link, it's isolated, but it was enough to make the arduino go spastic and tell me there's a power out (located about 1 meter away).

as for the bang, it's deafening not nice .... but sure was FUN!!!!


In high school (1970's) I once "plugged" several large (1000 uF) electrolytic caps into the outlets in the school metal shop. They shut off the circuit breakers at the end of the day, so the caps sat there until the next morning.

Next morning when the instructor turned on the breakers, all the caps exploded in a shower of paper shreds and smoking electrolyte oil!

Nobody ever found out who did it......... (http://www.hobbytent.com/images/smilies/laughingtohard.gif)
Title: Re: LOL - Exploded cap.
Post by: liuzengqiang on Oct 14, 2012, 06:11 am
krupski,

I hope your teacher catches you now that you confessed. On the other side of the fence, a retired colleague of mine used to charge up a large capacitor, realizing some of his students has fallen asleep during lecture, then discharged it with a metal piece. The loud bang woke up everyone, very angry. That's how he got back at the sleepers. I bet he'd use a ruler to slap them if they still allowed that. Waste of money, I say, to sleep in a classroom.
Title: Re: LOL - Exploded cap.
Post by: JoeN on Oct 14, 2012, 06:14 am

krupski,

I hope your teacher catches you now that you confessed. On the other side of the fence, a retired colleague of mine used to charge up a large capacitor, realizing some of his students has fallen asleep during lecture, then discharged it with a metal piece. The loud bang woke up everyone, very angry. That's how he got back at the sleepers. I bet he'd use a ruler to slap them if they still allowed that. Waste of money, I say, to sleep in a classroom.


The priests just used to throw erasers at us.  And we had to wear dark sports jackets to class...
Title: Re: LOL - Exploded cap.
Post by: Docedison on Oct 14, 2012, 06:25 am
Many years ago there was a trick played on Noob television technicians by the "Crew". The thing was to charge a 40uF cap to 200 - 400 V and carefully fold the wires (axial lead part) back to the capacitor body and then yell to the Noob "Here Catch" and toss the part at the noob. The practice came to an end one day when the guy that caught the "hot" one took the guy that made it and threw it outside and thrashed him severely. I'd have done the same If I had caught one... but I was aware of the practice... The sweeper filled me in first..

Bob
Title: Re: LOL - Exploded cap.
Post by: winner10920 on Oct 14, 2012, 07:10 pm
What's really fun is to charge a cap to like 200v, then "taze" unexpecting friends lmao
Title: Re: LOL - Exploded cap.
Post by: Docedison on Oct 14, 2012, 07:19 pm
That's Exactly what was going on... the real difference was asking the person to "Taze" them selves by saying "Here, Catch". Still was a mean trick and potentiallly very dangerous as there is a Lot of energy in a 40uF cap charged to 250 - 300 VDC at least 2 orders of magnitude greater than the Tazer...

Bob
Title: Re: LOL - Exploded cap.
Post by: winner10920 on Oct 14, 2012, 11:14 pm
Lol I musta posted that just after you did, didn't see that, it is quite funny, and it is cool how much energy the cap can disharge at once, I used a large cap charged to 200v to help me "safely " blow out the filament of a car bulb that I was going to use for a sort of neon lamp but just without the neon
Title: Re: LOL - Exploded cap.
Post by: fungus on Oct 14, 2012, 11:37 pm

Lol I musta posted that just after you did, didn't see that, it is quite funny, and it is cool how much energy the cap can disharge at once


If you put a screwdriver across that big capacitor in the photo the discharge welds it to the screw terminals. You can pick the capacitor up with the screwdriver...
Title: Re: LOL - Exploded cap.
Post by: Docedison on Oct 15, 2012, 12:33 am
Yeah but it is Hell on the screwdriver <BFG>... Gotta re-file the end to make it work right again. BTW I DO know what it is to be tazed, I've done it once or twice...
Back when TV's had tubes if the service tech couldn't fix it by replacing tubes, power supply diodes, circuit breaker and or cleaning the tuner (Big rotary switch), Drum type that actually switched RF, OSC and Mixer coils for each channel... Really Terrible with the Smog present at that time. The Chassis had to go to the shop and in the shop was connected to a test jig that was a CRT, deflection yoke and convergence yoke to replace the one in the house... If one forgot to connect the CRT ground lead you could pull a 1 inch spark to the unlucky fingertip(s)... and If one had the misfortune to have to work on an "OLD" Color set (The really early Color sets had a metal bell that was 3/4 of the CRT and it was connected to the HV supply (25 to 35 KV or more if the regulator failed) one had a "Snappy" experience. I oncxe left a picture tube on the floor in a house where I was in the process of replacing the tube and the customers dog sniffed at the 2nd anode button... Poor dog Never would come near me again. One only did that once... Perhaps twice if you were in a hurry or a slow learner. It IS dangerous to discharge a Really Large capacitor with a screwdriver. I had a "Spark" land on my head once, really burned and it was years before I realized that it might have been my eye except for luck and glasses. I shed the glasses when I got cataracts so I don't play any more.

Bob
Title: Re: LOL - Exploded cap.
Post by: fungus on Oct 15, 2012, 01:29 am

I don't play any more.


I only play with things that don't explode and can be switched on from a distance, eg. neon power supplies.

Title: Re: LOL - Exploded cap.
Post by: Docedison on Oct 15, 2012, 01:58 am
When I was young those things could be had for the trouble of dragging them home, I've made everything from room ionizers to rotary gap spark transmitters (Wiki that you'll be surprised). I had a "little Red Wagon" and a rope tether to tie it to my bicycle... My favorite things were discarded television chassis (s)... (SP?) there were literally hundreds of parts for the trouble of removing them and sorting them, I used Egg boxes for parts storage. I made my first AM 'Phone transmitter with a sweep tube a power transformer and a smaller B&W TV chassis ans a Heathkit (Anyone remember Them?) W5M Power amp as the Heising modulator (with a matching transformer) on a good day when the line voltage was about 125 Volts I could get 25 watts of power @ 80 and 160 meter wave length's and I had a 50 meter long Zepp fed transmit antenna... Worked great. I still am a Licensed Amateur Radio operator with the call sign WA7EMS... and I chose that vanity call for 2 reasons, it was my "Bootleg" call sign for many years also the phonetics are... interesting.

Bob
Title: Re: LOL - Exploded cap.
Post by: smeezekitty on Oct 15, 2012, 03:35 am
Quote

Worked great. I still am a Licensed Amateur Radio operator with the call sign WA7EMS

It looks like your license expired in June, 2012.
Title: Re: LOL - Exploded cap.
Post by: winner10920 on Oct 15, 2012, 04:48 am
Man I wish things like that were still laying around waiting to be taken, most tv sets I find(tubes that actually still have the coils that weren't hacked apart for scrap already) the parts I find are in horrible shape, and most times don't work
the best I find these days is power supply boards because most newer electronics have a separate board for the supply,
and unfortunetly in modern tvs the only high voltage parts is the fluorescent tube lighting supply, which some actually have served me well for some experiments,  but still I wish I were able to find something with vacuum tubes and all the cool older technology,  some reason while it seems harder and more complex to work with a vacuum tube just strikes me as more interesting than a little black transistor lol
the coolest older tech I got is a 1985 40x2 VFD which I figured out how to write to, which is kinda funny since its like 8 years older than me
Title: Re: LOL - Exploded cap.
Post by: smeezekitty on Oct 15, 2012, 06:18 am

40x2 VFD which I figured out how to write to, which is kinda funny since its like 8 years older than me

A VFD is a type of vacuum tube triode.
Title: Re: LOL - Exploded cap.
Post by: oric_dan on Oct 16, 2012, 12:45 am
Quote
Man I wish things like that were still laying around waiting to be taken


You might try visiting some weekend garage sales, not that I've ever been to
even one of them myself, but that might be your best bet.
Title: Re: LOL - Exploded cap.
Post by: winner10920 on Oct 16, 2012, 05:08 am
Trust me I always check them out if I see them driving around, people just have more junk these days, quality electronics are few and spare in my area
Title: Re: LOL - Exploded cap.
Post by: Docedison on Oct 17, 2012, 01:14 am
Yeah it was my birthday... I can't operate anywhere except vhf and uhf portable because I live in an apartmentand quite frankly the local repeaters drive me buggy... or they did the last time I was on the air... I have a bunch of 144, 220 and 440  MHz portables and I am too lazy to re-cap them. Real old school stuff Icom IC02?, IC03?,s and a Yaesu or two. Big OLD thumbwheel programmed transceivers... I bought a couple of AD9850 DDS boards... was going to rip out the synthesizers and replace them with NCO's... Still on my project list though as soon as I can figure out how to modify the Icoms... they used a varactor tuning system for the receiver RF and mixer and would be rather numb at best without that tuning. I have often wondered why there wasn't an Amateur Radio group here... Too

Bob
Title: Re: LOL - Exploded cap.
Post by: retrolefty on Oct 17, 2012, 01:23 am
Quote
I have often wondered why there wasn't an Amateur Radio group here... Too


There are a few of us around. However beyond a morse code encoder/decoder project or two, not many ham projects get posted around here.

Lefty: WA6TKD

Title: Re: LOL - Exploded cap.
Post by: cjdelphi on Oct 20, 2012, 11:14 am
Yesterday while cleaning up, I found the metal shell casing, nice and smooth except 1 corner where it must have hit the wall um.. hard :)
Title: Re: LOL - Exploded cap.
Post by: fungus on Oct 20, 2012, 01:01 pm

Yesterday while cleaning up, I found the metal shell casing, nice and smooth except 1 corner where it must have hit the wall um.. hard :)



Now imagine it hitting your eye...

Title: Re: LOL - Exploded cap.
Post by: cjdelphi on Oct 20, 2012, 03:45 pm
I'm an unlucky but lucky kinda guy lol...

at 16, I decided to see how far I could make a hard rubber (high bounce ball) ball bounce, firing at it, while standing next to it, I aimed down fired... next thing i know i'm in severe pain clutching my right eye, turned out the 177 lead bullet hit the ball and decided to ricochet off directly into my eye..

Lucky thing was, it hit the bone just above my eye just below your eyebrow - I tell you what, that hurt like HELL....  and it taught me a valuable lesson, wear eye protection :) - which i never did do! - when firing over 7 feet away with an air gun I'm not that worried....

I've been in plenty of "what if's" one day i'll get unlucky... but that's the way i roll ...  I'm sure if you talk to enough guys who operate lasers and play with lasers at least 1 of them has only 1 working eye ball :) i still got a 2nd one :D
Title: Re: LOL - Exploded cap.
Post by: krupski on Oct 20, 2012, 09:04 pm

krupski,

I hope your teacher catches you now that you confessed.


Since I went to high school 1971-1975... my teacher is either older than dirt or dead.

There were a few other things I did in HS that I've never confessed to (and nobody knew who did it).

A little knowledge plus the underdeveloped morals and common sense of a teenager = nasty pranks.

Thankfully, nobody ever got hurt.