Before an important demo, the power supply engineer was nervous. Really nervous.
In early 1980s, I was a member of a team working on a nuclear magnetic resonance system, which required a very stable 100V 10A power supply for the magnetic field.
The stability requirement was a tough ~1ppm of noise and hum, and my colleague who was designing the power supply built a coarse 3-phase thyristor regulation, followed by a smoothing linear regulator.
To his big disappointment, those thyristors, even when abundantly over-dimensioned, kept misfiring, and the high inrush current into a large capacitor bank kept melting the semiconductors down, and causing in turn a short on the 3-phase mains, triggering the automatic circuit breakers, both on the PS rack, and the main ones, shutting the whole department off. It was happening several times a week, so it soon became rather annoying.
Finally to everyone's relief, my colleague has managed to reduce that inrush current, and also obtained some 70A rated thyristors, which cured the problem.
As the delivery day of the NMR system approached, we invited a professional photographer to take pictures for the documentation, and that's where I got my bad idea...
Demo day arrives
On the day before the demonstration for our customer, we were all busy with the last checks and preparations, and the PS designer was naturally rather nervous himself, he was sitting by the PS and an oscilloscope with the probe attached to the output voltage, the input AC coupled and the sensitivity maximized to show the line ripple, fine- tuning some trimpots, and watching carefully the changes on the output waveform.
I approached quietly behind him, with a photographic flash light fully charged, and as he reached once again for one of the trimpots I pressed the flash button. The flash light fired with a silent "PUFF".
For a few microseconds the time stood still. Then as in a slow-motion my colleague jumped up, the screwdriver which he was using to adjust the trimpots went left, the chair flew backwards, his glasses to the right and as he was falling on the floor he reached for the power switch and pulled it down.
The room burst into laughter.
After we all calmed down again my boss approached me and told me that my little joke could have had some very serious consequences if, by chance, my colleague dropped the screwdriver into the PS.
"I know, boss," I said, "so I gave him my plastic screwdriver last week!"
Once when I was at tech college, we were looking at a 1kW transmitter. My friend and I hid behind it (it was a full rack unit with some nice big bottles in it). He lit a cigarette and blew some smoke through from the back. I waited a bit - till the smoke would have been wafting out the front - and then banged the side of the cabinet. Our instructor shut down the transmitter's main power supply pronto. He had a bit of a sense of humour failure and I don't think ever really forgave us, though he did see the funny side of it a bit later. I realised that that it is best to pull these stunts on your colleagues or equals, not your boss or instructor.....
Once when I was an electronics tech fixing pro-audio gear, I was deep into troubleshooting a power supply on a tape deck, when my boss, ever the prankster, rolled his chair over a sheet of bubble wrap. Thought I fried the whole supply and it took quite a while for my heart rate to return to normal.
This reminds me off our boss and sales and marketing department. We did many projects for US DoD and after sending First Article (FA), we at Engineering and Design department eagerly await customer feedback. Many a time my boss and sales people play possum and give us wrong feedback that there is problem in FA and is coming back or order may get cancelled. The concern engineer is so worried for few days or hours and eventually they tell the truth. By this time, they take out some improtant information from us or has got some realy low price for engineering job.
I was working on a bench that looked through the risers on my bench and the one facing my bench towards a third bench where the other hardware design engineer was bringing up an offline smps. There had been had a few small explosions of the power switch as the unite was being tested under high line conditions. I had received a new part packed in large bubble wrap. Not intending to cause a ruckus but just because it is fun to role the stuff up and twist it to pop several bubbles at once, I did. I did not know the guy working on the supply was just turning it on as I gave the first big twist with several loud pops. That guy must have jumped nearly a meter in the air and slammed the switch off. Seeing him jump like that I walked around the bench to see him shaking like a leaf. I apologized and he told me that he was just turning the thing on at high line when the bubbles popped. He went out and smoked a few cigarettes before returning to work. On the next power cycle his supply did emit it's own rather loud report again. I eventually took over that project and that supply is now employed world wide. Even in Russia where the power can swing between 190 and 300VAC!
Back in the 70's I curiously watched as a technician merrily was twisting together a bunch of 4.7 ohm 1 watt resistors together while across the lab another design group was about to power up a several hundred watt switching power supply for the first time. The dynamics of switching power supply design back in the 70's meant there was quite a bit of trepidation during First Turn-On. Meanwhile, our tech had hooked this string of resistors up to a variable transformer connected to the AC line and place them in front of a computer fan. As they started up the power supply, He turned up the voltage just enough to make the resistors began to sweat. After about a minute a very faint wiff of "O' de Ohm" made it across the room, and suddenly we hear "SHUT IT DOWN! SHUT IT DOWN !". I made it a point to not stand to close to the chuckling tech as these miffed engineers turned around and glared.
Thinking back, I wonder sometimes if I was just an irresponsible idiot at times. Maybe i was, but it now seems that my distorted sense of humor is shared by a large number of excellent engineers. I'm relieved to discover that. Thank you all.
Joshua...there's a saying that's very relevant here.
"It's never too late to have a happy childhood"
Which is I think what most of us were doing when we got up to these pranks. In most cases they did no long term harm to anyone or anything.
As you've observed, Engineers by and large have a good sense of humour (sorry, humor to you!)and often the jokes are appreciated as much by the "jokees" as the joker. I don't think it's irresponsible, jsut makes work more fun.