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Dr. Drone

Tue Apr 08 2008, 03:17PM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
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Posts: 1673

HV Enthusiast

Tue Apr 08 2008, 03:29PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

Yeah, i agree with Chris Miles. Keeping one hand in pocket ensures you won't develop path across your heart. Very good advice.

And also, always wear your safety goggles, especially when dealing with power semiconductor devices which tend to explode violently when they fail. Remember, you only have two eyes.

Ultra7

Tue Apr 08 2008, 03:34PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Ya know, it is because of this particular thread that I started wearing safety glasses when i solder. I've been hit in the face by some flux trying to look too close at what I was soldering ( really small space on a poorly designed board). I always meant to wear the glasses after that happened, but now I do it because I know what can happen.

I work in the Cable TV industry where we power the actives with 60VAC at around 11 amps. If you have to splice it together in the middle of a rainy night because some dude didn't locate his utilities before putting in a new fence, you will get bit. I don't like it, but sometimes you just get juiced. I usually try to de-power the system from upstream, but sometimes you have to "Hot splice".

I guess it is better to learn someone else's mistake through reading about it, rather than not knowing about it and doing the same thing.

Andyman

Tue Apr 08 2008, 09:57PM

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

Yes, it was one of those red ones. They make a mighty good mini marx gen! They hold a lot of energy for just 650pF! When I clicked on that picture, I seriously sat there for a full minute in awe of the sheer mass of capacitors.

I've also been shocked by my voltage multiplier for my induction launcher charger, luckily on just one hand. I was going in to disconnect an output lead, forgetting that the 22uF multiplier caps were still charged. I had the output lead in my hand, and being DC, I didn't feel anything. But then the tip of my ring finger brushed up against the other side of the "bank" and boy was I surprised. My whole arm jolted, and when I pulled it back to look at it, I noticed a nice tiny hole where my knuckle had touched the cathode, about 1/16 inch across. The air around the charger stunk of burnt flesh for a minute or two. It was probably one of the worst shocks I've ever had, even though it was only around 650 volts. My wrist and hand were sore for about a day after.

Shaun

Wed Apr 09 2008, 01:27AM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

Recently I upgraded my half-bridge SSTC to a full bridge, and the fuse in my variac was blown so I decided to plug the bridge rectifier directly into the 120V mains. WRONG! Break rate was about 4Hz, and as I slowly turned up the PW I saw hair-thin 10 and 11 inch arcs coming out.

At this point I was ecstatic, so I turned the pulse width up a little more and suddenly... CRACK!!NNNNNNNNNNNNNNNN [deafening 60hz hum]. That MOSFET threw sparks about 2 feet across my bench, and blew an MUR860 and two tvs diodes clear off the bridge and across the garage!

I was lucky to have been wearing goggles, because in all honesty if my variac had been working I wouldn't have been wearing them...

Weston

Wed Apr 09 2008, 01:48AM

Registered Member #1316 Joined: Thu Feb 14 2008, 03:35AM
Location: Cambridge, MA
Posts: 365

I discharged 300 uf of photo flash caps across both my arms while trying to build a coil gun an a altoids can. Burnt my finger and could not feel my arm for a day.

Myke

Wed Apr 09 2008, 05:18AM

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

@ 300V that's about 13.5J

Isn't it 16J across the chest to affect your heart?
Please be careful

Andyman

Wed Apr 09 2008, 05:40AM

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

Sheesh, you got a mini defibrillator action goin on there! If anyone in my family has a heart attack, and the meds can't get there in time, I might just use my launcher's cap bank charged halfway!

I hope you know I'm kidding

ahron11

Sat Jul 05 2008, 03:11AM

Registered Member #1572 Joined: Fri Jul 04 2008, 11:14PM
Location:
Posts: 19

Recently while I was working on my 3KJ coilguns first stage I was firing it with and experimental metal barrel (copper) and I held the barrel while I fired it. The barrel shocked me, and just in case you were wondering there were three 2400uf caps at 450VDC. Another thing I did when I was like 13 was take apart a TV and I clipped the flyback transformer output, and there was a hole in the insulation of the clipper I got shocked. Probably from the stored voltage in the CRT or in the flyback. Also Dr.Shock I'm sure that something has happened to you too.

aonomus

Sat Jul 05 2008, 04:08AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

My RL job as a live event tech sometimes involves 3 phase power. I've seen a green tech unplug one of the live phases under load (failed idiot check, he didn't check the current gauge saying 200A was going through that particular phase) causing the camlock connectors to arc momentarily as the blood drained from the poor guys face. He wasn't injured, but the connectors had to be replaced....

As for HV, the only shock I've ever gotten was from a disposable camera board running without the photoflash capacitor, just enough to jerk away. The current ran only through one finger, no cross-chest current.

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