Take a peek at ...
http://www.ananova.com/news/story/sm_871967.html?menu=

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:

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I need a memory upgrade ...
My head is full !

 

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.

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Dave Cutcher
Electronic Circuits for the Evil Genius

 

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

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I'm no electronics god, i just talk too much.

 

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.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

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.

 

Along the lines of popping electrolytics. When I was a graduate student, I took a power electronics class which had a lab component. In the lab part one of the early projects was to build a buck converter. Rather than write your name on it though, you were to put an assigned number. Then the professor would randomly reassign projects. So now you had somebody elses (and you didn't know who) and some third person had yours. Then you had to debug their circuit and modify it (first to a boost, then you exchanged again and modified it to a buck-boost). In any case, one person mounted the cap backwards, but it managed to work (at least to some extent) for the few days they modified the project. But when the next person got the project, as they were working on it, the cap went off like a shotgun. It was *loud*, though the ensuing laughter was even louder.

 

thats wut i thought!! (am i igniting a theory discussion here?)

__________________
I'm no electronics god, i just talk too much.

 

wanna pop a capacitor the most idiotic way?

do this:

step 1: take a refrigerator and snip the plug wire.
step 2: remove about 1/2 inch insulation at the end you cut. this end must be able to plug into the wall.
step 3: separate the ends so that the wire forms a Y shape.
step 4: connect an electrolytic capacitor with a low voltage rating (say 10V) to the wires. Now you will have a complete circuit.

and the fun step, step 5: PLUG IT IN!

and if you want to get more crazy, smash your monitor and take a capacitor from it.

Ok, I'm just being silly now, but hey, I'm following the subject

 

I can make that much simpler, Just use a capacitor with long leads and cram it in a wall outlet. no refrigerator cord cutting needed

__________________
Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

cheap extension cord if u dnt want a big brown burn spot on ur outlet :lol:
i REALLY gotta try this. i got a couple boards full of 100, 220, 100 uf 10v caps :twisted:

__________________
I'm no electronics god, i just talk too much.

 

:twisted: hee heeeeeeeeee :twisted: i tried the cap popping w/ wonderful results. this is my tutorial for newbie cap poppers:

find an old piece o junk extension cord. i have a couple that are used for attaching things like christmas lights. now cut off about 6 inches so u have a piece of cord w/o the plugs. strip both ends of the cords. now put alligator clips on two of the ends. now attach the your capacitor to the alligator clips. make sure that you attach the clips as close as u can to the capacitor otherwise u might fry the capacitor's leads because they aren't meant for 120v :twisted: (thats where i went wrong). plug the other two ends of the cords into your extension cord OBVIOUSLY WHEN THE EXTENSION CORD IS NOT PLUGGED IN, DUH!!!!

now wut i like to do is plug the extension cord into my powerbar when the powerbar is not turned on. that way i have a switch that i can flick. also, the powerbar will automatically shut off if your two clips accidently touch each other, then u dont have 2 go out to the breaker box

dont use capacitors w/ vents on the top. if it has lines on the top of it, that means it has a vent. only use capacitors that are solid on top. the vents are there so that when the cap gets connected to too high of voltage, it doesnt blow up, it just goes ssssssssssssss. BORING :roll: !!


now, questions:
wut makes the biggest boom? i was using 47 uf caps rated @ 50v. i thought i had a bunch of 100 uf caps n stuff but i didnt.

i take it the voltage rating should be low and the uf high as u can get it.

where might i find some big caps w/o the bloody vents? i was thinkin of going to a thrift shop and picking up some really old piece of electronic equipment.

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I'm no electronics god, i just talk too much.

 

The bigger cap value the better, also as long as the voltage rating is below 120Vrms, or maybe it could be above 120V because it's actually 169.7Vpeak. If it wasnt starting to snow here, I'd play with some LARGE caps that I have sitting around :twisted:

Maybe you can put some epoxy over the ones with the vents to seal them up for a bigger boom. :twisted:

Old electronics is great to salvage from. make sure it's the older stuff though, the newer stuff uses that surface mount stuff which cant be salvaged.

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Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

Hi Jeff,

I like to see the chainsaw where the piston fits!

 

It's not from a chainsaw, its from my lawn mower. :lol:
http://www.mymonte.com/download.aspx...ssageID=203527
http://www.mymonte.com/download.aspx...ssageID=203527
http://www.cardomain.com/member_page...2_131_full.jpg

But seriously, if you're wondering, I got it from salvage at work, it's for a 4400 HP desiel locomotive engine. Paid 10 cents a pound so it cost me $13.70 (137 lbs :wink: )

It's amazing to think about 16 of these 137 lb pistons moving up and down 1170 times a minute.

I'm looking into possibly selling it if anyone is interested

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Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

That's only a baby piston!.

I watched a program a while back on a Korean ship builder, they make the biggest ships and biggest engines in the world. I can't remember the exact size of the pistons, but there was an access DOOR to the big ends, where you could walk in and examine them!. Certainly the pistons were measured in feet, not inches :lol:

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk