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Most "wrong" fun in the lab/shop/biz/bench? Keep it clean!

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djacobow:
I have put nails through some charged lithium cells and been rewarded by a jet of flame. But recent cells don't seem to do it? Have they added some new safety features?

nctnico:

--- Quote from: ccktek on November 09, 2023, 08:00:47 pm ---Late 1960s: One of the engineers in our lab was working on a big rat’s nest breadboard circuit.  When he was away we snaked some thin clear plastic tubing into the circuit from a nearby bench.  When he returned we blew smoke into the tubing.  He first switched off the power supply – more smoke.  Then he switched off other attached test gear – still more smoke.  Then he frantically pulled out mains plugs – more smoke.  Finally he discovered the end of the tubing.  In retrospect I wish we hadn’t done it, but that’s what normal young smart-asses do.

--- End quote ---
A long time ago I instigated a more positive prank. One of the older co-workers brought an old style phone that used to be in his parent's house to put it as an ornament on his desk. He claimed it was broken. When he wasn't there we investigated the phone and concluded it could be made to work with some simple fixes using part we had around anyway. So one day we fixed it and patched it into the company's phone system. The face of the guy when it rang and there was somebody at the other end of the line when he put the handset to his ear was just golden.

coppercone2:

--- Quote from: djacobow on November 09, 2023, 11:15:12 pm ---I have put nails through some charged lithium cells and been rewarded by a jet of flame. But recent cells don't seem to do it? Have they added some new safety features?

--- End quote ---

IDK those have flammable liquid, the primary is reactive metals, so if you smash a leak into it and throw it into a puddle over stone it sometimes get interesting. But like a jumping jack it can probobly fly away or explode and shoot out like a cannon.

PwrElectronics:
Early 90s I worked at a place that did industrial VFD repair.

The owner had collected a lot of "stuff" in the basement for plans to make homebrew dynos.  Amongst the collection were a lot of current transformers for use with panel meters to measure mains loads.

One day after hours, I gathered up a few of them at different sizes and chained them together.  Input was a variac off the AC line and the output was a loop of 0000 cable.  Put 1500A range clamp on meter on the loop.  One could turn up the variac and get I think it was 1200A in that loop.

I discovered putting ones hand near that loop made if "feel funny".  Not sure what was happening there with the magnetic field and my body but I didn't do it very long!!

Couple of years ago I was trying to duplicate some failures the customer had on a item I designed.  I eventually got the clue from them that a loose battery negative cable could be involved.  Failures only happened during engine starting.  So, my test setup had a large 12v truck battery, a contactor I could engage with a push button, a big iron core inductor to simulate the inductance of a engine starter motor and several feet of battery cables.  The trigger of the contactor basically shorted the battery through the inductor and cables.  So, some large currents with flyback spikes on the loose (deliberately so) bolted joint in the cable was possible.  I had lots of flashing and melted ring terminals and the loose bolt.  It looked pretty rough by the time I was done.  After my contactor stuck once and melted off the cable, I put in a 250A fuse when I replaced it.  No need to risk having the battery explode.  That type of fuse would pass the current longer than my intermittant engagement of the contactor.  I am sure I likely had 1000A in there but didn't try to measure.

coppercone2:
that's weird, I have a brazing transformer that I have wired up with 0000 cable. If I stand in the middle of the loop while holding an electrode (with the other one clamped) I feel nothing. Though usually I stand outside of the loop, but it happened before.

It does shake stuff though, perhaps you just feel vibrations? The current levels are like 1500 amps+

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