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Say cheese! (change pants later)

Erik Margan
1/27/2011 11:13 AM EST

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meterman
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re: Say cheese! (change pants later)
meterman   2/7/2011 3:01:42 PM
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When I was in school in the late 60's, We would have to build up circuits on a proto board, and hook up a bench supply. Several times we concealed old-fashioned photographic flash bulbs in the protoboards, and wired them to the power. When the victim flipped on the power supply toggle switch to start work they were greeted with a huge flash and pop. I also remember removing and reversing the cardboard sleeve on foil capacitors. The victim would then not know that they had wired the capacitor in revese polarity. When powered-up this would produce an startling explosion. Sometimes it would un-roll the capacitor.

mtripoli
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re: Say cheese! (change pants later)
mtripoli   2/7/2011 10:59:25 PM
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In high school we had an electronics program. The classes were taught in a detached "trailer" that had its own electrical service. The service was located in the back of the trailer; first one there got to walk in the dark to the back and flip on the breaker. There were desks in the middle facing the board, with electronics stations lining the sides. These held a scope, DVM and bench power supply. One day I decided it would be funny to wire small electrolytics (1uF) across all the power supplies backwards and turn the supply on with the main breaker off. Whoever got there first would turn the breaker on and before they got to the front of the room the caps would be exploding. Well, it was the teacher that got there first, and once everything settled down he was not happy. A "little" joke got out of hand when someone decided if a small cap was good, a bigger one would be better. They did the sme thing but with something like 4700uF. The unreal mess was not expected, and someone could have got very hurt (ok, I know, you could get hurt from little ones as well, but I was a kid). After that anyone doing it would be expelled. That was also the class were we decided wiring a sign transformer (15kV) to the handle on the door was funny as well...

old account Frank Eory
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re: Say cheese! (change pants later)
old account Frank Eory   2/8/2011 12:26:53 AM
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Here's one some of you may recognize: In the old days before test equipment had data storage and file I/O, we used to do data collection with Polaroid cameras that nicely fit over the display of the scope or spectrum analyzer. The Polaroid film needed to be coated to preserve the image, and each film pack came with a plastic tube containing a squeegee full of the coating goo. The cap on that plastic tube made a very tight seal. The plastic tube, filled with dry ice, capped and casually dropped into the victim's lab coat pocket would eventually warm up and the CO2 pressure would blow the cap off with a loud popping noise :)

NOAA
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re: Say cheese! (change pants later)
NOAA   4/1/2011 11:35:42 PM
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When my roommate and I were working at NOAA during college, his boss was ready to play a joke on him. He had a new circuit built, an o-scope ready to test, and his back to the hallway. His boss walked up behind him with a tall, empty metal trash can that he was going to drop when the probe first touched the circuit. Unfortunately for my roommate, he had a hot AC line where there was supposed to be a low-voltage signal. The probe flashed and self-destructed, and his boss never got the chance to drop the can. An orignal ROFL followed.

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