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Andyman

Sun Apr 06 2008, 09:51PM

Registered Member #1083 Joined: Mon Oct 29 2007, 06:16PM
Location: Upland, California
Posts: 256

I thought it would be interesting to have a thread where everyone can share some of their "shocking" experiences and other stories. It can be related to chemistry, high voltage, electronics, tesla coils, computer disasters, etc. For example, the story of your worst, near death high voltage experience, or the story of how your hard-drive burst into flames. (that actually happened to me)
I'll start to give an idea.
A few weeks ago, I was experimenting with my NST, half wave rectified, and some hv capacitors. I was drawing little static arcs from the sides of the capacitor, holding the two, well insulated 'gator clips in my fingers. Normally my fingers are one big callus, therefore providing a bunch of hv resistance. Well, I had forgotten that just a few minutes before, I cut the end of my finger with a box cutter. That left my blood vessels, a favorite path for hv, exposed. My barrier of dead skin was broken. As I put the clip up to the side of the capacitor, it arced into the cut, across my chest and down my other arm to the other side of the cap. Needless to say, my first reaction was a violent pull away. The chair behind me had a reciprocating saw on it (I was experimenting with mechanical resonance) and I hit that, launching it off the chair and onto the floor. I sat in the chair for a few minutes, my heart racing and me sweating. The voltage was around 9kV out of my 12/30 nst, with the included pulse from the cap.

I think I will finally get around to making a few small "chicken sticks" for drawing arcs.

Electroholic

Sun Apr 06 2008, 11:43PM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

yea, they are not medals of hornor, and should not be discussed as such here on this forum.

teslacoolguy

Mon Apr 07 2008, 01:44AM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

About 1 month ago i was building a sstc driver circut and my face was over it as i was testing some things with a oscilloscope and all of a sudden BOOM!!!! one of the large electrolytic capacitors in the filter circut exploded spraying hot capacitor oil right into my face and my eyes burned for about a week and i had a couple burn marks on my skin.

Backyard Skunkworks

Mon Apr 07 2008, 02:03AM

Registered Member #1262 Joined: Fri Jan 25 2008, 05:22AM
Location: Maryland, USA
Posts: 451

Back when I was 11 I got a few disposable cameras from the local photo developer, I wore thick leather gloves and took the first one apart just fine and discharged it. Then the second one, I was having a hard time getting the battery out so I took the glove off my left hand to pry it out. I didn't know that the battery clips were hooked directly up to the flash capacitor. Well my hand made a circuit with the capacitor discharging from my left little finger to my left thumb. ZAAAAAAP, I threw the camera to the floor. Later that day I was the fastest kid at baseball practice, as I was still on edge. I learned not to take the gloves off when its over 50 volts at any real current.

Then there is the time I hooked a boost regulator up to the toilet! Good times... Good times... Whenever someone let off Hydrogen Sulfide, I'd let 'em have 330VDC at 5mA across the buttcheeks, they never knew what hit 'em.

rp181

Mon Apr 07 2008, 02:10AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

same thing happaned to me. The cap wasn't even fully charged, i got shocked and by reflex threw it across the room. It still had enough power to make the flash go off when it hit the ground =/ That was painfull.

Myke

Mon Apr 07 2008, 06:38AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

I've got a couple painful shocks from disposable cameras when taking them apart.

I've had a blob of molten solder fly onto my hand. I was desoldering the xenon flash tube of a disposable camera and the solder wasn't melting. So I pressed harder and rotated the tip a bit. All of a sudden the solder melts. The solder was on a copper strip that kept the xenon flash tube in place. A tiny blob of solder landed on my left hand. At first I tried to blow it off by blowing on it but it stuck to my skin. It cooled off pretty quickly and then I flicked it off. Where the solder landed was a bit red. A couple days later the burned area turned black and a couple weeks later faded away.

note to self: don't apply too much force to solder when waiting for it to melt.

flannelhead

Mon Apr 07 2008, 11:50AM

Registered Member #952 Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388

I've never had a shock from a disposable camera

I was desoldering a flash tube from a disposable camera too. The solder on the joint was molten and I pushed the copper tab a bit downwards. Then I accidentally took the soldering iron off and all the molten solder was sprung by the tab to my face! Fortunately I barely shut my eyes just before the solder flew.

Steve Conner

Mon Apr 07 2008, 12:47PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I once worked as a technician at BBC Scotland, and they required you to wear glasses when soldering (either normal or safety) for this reason. They told me that they brought the regulation in after someone lost an eye when a glob of molten solder flew into it.

They got me into the habit, and I've worn glasses when soldering ever since. It's a good idea, especially if you think that the thing you're soldering might spring loose and fling the solder at you.

BTW, like another poster mentioned, these accidents are *not* medals of honour!

flannelhead

Mon Apr 07 2008, 01:06PM

Registered Member #952 Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388

Yep, wearing protective glasses would be a good safety excercise.

These accidents certainly aren't medals of honour. But I think this thread is good for learning through others' errors.

Avalanche

Mon Apr 07 2008, 01:50PM

Registered Member #103 Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845

When I started my current job the first thing I had to do was to choose some safety glasses. I did neglect wearing them for a while, until one incident. I was investigating a problem with a 10kVA inverter where there was a lot of ringing on the busbar even under no load - so I'd come to the conclusion that there was a shoot-through problem on one phase. Anyway I decided for an initial check I'd scope all the gate drives. The lowsides were ok... now onto the highsides! I plugged the scope into an isolating transformer, and began checking the uppers, obviously clipping the ground lead on in the right place. When I did this, the inverter kept shutting down with overcurrent, so I thought it would be a good idea to disable all the overcurrents with wire links and try again

This time, instead of a shutdown, I got a nice foot-long dirty orange flame jump out and hit me on the head! I'd taken out both devices on one phase. It didn't really make a bang, just a loud whoosh! So now I always wear my glasses!

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