Many years ago I was working on a military contract for a portable test set and was responsible for selecting a battery to power the set. I selected an early sealed gel-cell battery, largely because of its low temperature performance. The company decided to produce a commercial equivalent, but due to cost restraints used a vented cell battery instead (fortunately not my decision). After transporting the commercial set across the country via air to a hangar, the test set exploded from the hydrogen and oxygen liberated during charging, hitting an air conditioner at the top of the hangar. No one was hurt, but that was the end of that project. I still am wary of the lithium batteries in my laptop.
Oh many decades ago,
working on a project where we needed TTL voltages, 5 v , but for some reason, we though tit a good idea to distribute 5v around .
QED, some big Kw power supplies, wired in parallel, with big copper bars connecting to the rack.
You want to see what happens when you leave a spanner across the bars when the power is turned on,,,,,,,
Wasn't me,,,, really ...
but a room sprayed in real copper is very impressive.
I was on a team rushing to finish a piece of equipment the night before a customer demonstration. After working through the night wiring, assembling and checking, the moment of truth came. We plugged in the device and flipped the power switch. What ensued was the equivalent of a DC 4th of July celebration all taking place within the space of about 8 cubic feet. But instead of oohs & ahhhhs, there were different words and sounds uttered. It turns out that the particular power strip chosen for the occasion unfortunately was homemade and had its line & neutral reversed internally, and since it was just a demo, it was decided that we would forgo the usual formality of an isolation transformer in the interest of expediency. Fortunately, we had 2 of everything and that night we needed it - except for the homemade power strip.
I started as an electronics tech in the US Coast Guard and have a few stories from that. One that somewhat haunts me to this day is a call I had to fix a 'broken radar' on a 44 foot rescue boat at the Cape Disappointment, WA small boat school. This is where they teach guys and gals to take the small boats out when everyone else is coming in - the training ground is the Columbia River bar. The boats always go out in pairs in case something goes wrong.
I showed up and the on-site senior electronics tech was convinced the antenna was shorted - becuse it was a 50 ohm antenna and the ohmmeter showed no resistance. While I knew better (impedance vs. resistance) we swapped the antenna. When that didn't work, the second boat got tired of waiting and went out in a brand new 41 foot harbour boat. A freak wave caught them - some never came back.
I figured out the radar was misconnected - nothing wrong with it. Wish I'd been faster.
Google UTB 41332 for more details.
I managed to destroy a Makita drill in short order by inserting a power pack in backwards. The smoke was pretty impressive. I offered to pay for the repairs. Later my friend comes back to me saying they don't make that drill anymore because this was a common problem. I simply bought my friend a new drill. This isn't the first time I've fried something by getting the terminals backwards.
If there is any way to insert a battery in backwards, it will be done.
I was once interviewing a new EE at our company. The interview was almost over and as I walked him back to Personnel we stopped by the Engineering Lab to show him around. I told him to keep his hands in his pockets as we had lethal voltages out in the open. He asked what I meant by lethal voltages? I walked over to one of our products that was under development and pointed to the large buss bars saying "Touch this and you Die!" He retreated immediately from the Lab and walked out of the building never to be heard from again. Up to this point I had thought he was a bright Engineer worthy of a very good job offer. Boy, was I wrong...and he had a degree in Power Engineering!
Being an engineer requires on-going study. Not only do you have a catch up with the technology advancement but also learn the new measure that you or your team members have figured out.
Mistake in Civil and Power Electronics can be fatal. Mistake in system and software engineering can cause a lot of trouble. You would think after 10+ years of Internet development that most cloud based system is secured. What happened to Yahoo yesterday has proven it to be wrong.
Nowadays, technology advances faster than anyone can get their hands on it, not to mention wrap around it. Due to various reasons, without fully understanding, people start using the technology and building a new product based on the technology. We are in the culture that we learn while we are doing it. No doubt we have to act so as to put ourselves into a better environment of learning. Yet, proper measure shall be taken. Knowledge from an experienced engineers will definitely be one of the key ingredients to keep yourselves from trouble.
When I was younger I had a summer job at a paper mill where my dad worked. I studied electronics so I worked as an apprentice automation mechanic. I was working with one engineering student and we did random odd-jobs at the factory: everything from changing light bulbs to small automation installations.
One day we got an assingment to replace a fan on a control cabinet of a huge measurement unit that measured the thickness of the paper. We went to change the fan and we turned off the automatic fuse of the fan system, just in case.
Apparently something was not right because when my work pal started to screw off the broken fan a visible loud spark stroke out from the fan to the screwdriver and the whole measurement unit died. Few seconds after that my dad calls and asks did we do something because the whole lower level of that paper machine went dark and was operating on emergency power. With some stuttering we told that we might have caused some sort of short-circuit.
Later we found out that the spark extravaganza burned the main fuse even though it should have been impossible to happen. The whole fan changing fiasco resulted in few kilometers of ruined paper that had to be scrapped. Fortunately the 200k€+ measurement device was not damaged.
Blog Make a Frequency Plan Tom Burke 17 comments When designing a printed circuit board, you should develop a frequency plan, something that can be easily overlooked. A frequency plan should be one of your first steps ...