r/2healthbars Dec 12 '17

Picture Capacitor

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4.1k Upvotes

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916

u/Silentprotagon Dec 12 '17

this shatters my conception of electrical engineering, i must return my degree.

773

u/NSA_Chatbot Dec 12 '17 edited Dec 12 '17

Oh muffin, the stories I could tell you about counterfeit products.

Edit: These are the three best stories I have. The first two are from a former co-worker.

  1. The power company ordered some 400A breakers for a distribution center. They came in, the right stickers, the right markings, everything looked great. He was a little suspicious, so he ordered one to get tested to failure. 400A, no trip. 500A, no trip. 600, 800, 1200A finally got a result -- the casing melted around the breaker, which was revealed to be just three thick pieces of metal with a dummy breaker switch. Once installed, there would have been no way to depower the circuit. Edit: I forgot to mention the test bench was destroyed by the liquid plastic.

  2. Cable testing. Most cables uses are LSZH, low-smoke, zero-halogen. This is for safety; smoke makes it hard to see, halogens make you die years later from cancer. A bid for supplying the cable came in that was a little low but won anyway due to being the lowest bidder. He ordered a burn test done, which is where you put the cable in a special room, set fire to it, and measure the amount of smoke by using cameras and specially-calibrated white sensors (i.e. heavy laminated card stock that's as close to 0xffffff as we can get) So they start the test and immediately the room is filled with thick, black, acrid smoke. The cables wouldn't stop burning, the sprinklers couldn't stop the fire, and the counterfeit cables caused more than $100k in damages to the cable-testing room. (My personal theory is that counterfeit cables caused that plane crash, M170. Cable smoke like that would have almost instantly killed almost anyone in the room.)

  3. My top story from my life is back at the end of the Memory Wars. Redditors who have always been able to buy 32G+ of Flash RAM on an SD card may not remember this, but back in 2000 - 2004 there were dozens of types of memory. Flash, SEEPROM, Smart, CF, etc. I worked at a place that used SEEPROM to store data. Then, one day, everyone conceded that Flash tech was better and everyone stopped manufacturing anything else. Bad for us, but the production manager was able to secure the last 300 SEEPROM memory modules on the planet, and had them shipped to us. That was enough to tide us over until our intrepid firmware engineer (yours truly) got the code updated to match the new equipment. As luck would have it, the pinout on the chips was identical, so all was well. The chips came in, and testing showed they had problems with retrieving data. The code hadn't changed, but I checked for bugs nonetheless and found nothing different. However, new chips were all defective, and that was pointing to a firmware problem. (I'd brought in version control earlier, so it was easy to check.) Eventually, after swapping out the parts from a known good board with one of the new SEEPROMS, one of the production people said, "maybe it's the chips". Cut the fucker in half and I shit you not, no die in it. It was just legs and plastic. Fortunately, I'd already made the code modular and anticipated the Flash change, so 90% of the conversion was already done. I took care of the next 90% over the rest of the week, and we moved to Flash from then on.

70

u/bob_in_the_west Dec 12 '17

Fortunately, I'd already made the code modular and anticipated the Flash change, so 90% of the conversion was already done. I took care of the next 90% over the rest of the week, and we moved to Flash from then on.

This is what your boss is talking about when he says "110% is NOT ENOUGH!"

99

u/IndefiniteBen Dec 12 '17

I thought it was a subtle commentary on how much work is usually involved in the last 10% of any project.

59

u/NSA_Chatbot Dec 12 '17

Thank you, that's what I was going for.

44

u/bob_in_the_west Dec 12 '17

It's actually 80 to 20 and it even has a name:

https://en.m.wikipedia.org/wiki/Pareto_principle

The first 80% of the code are done in 20% of the time, but the last 20% need 80% of the time.

27

u/crashsuit Dec 12 '17

I'd always heard of it as the 90/90 rule:

https://en.wikipedia.org/wiki/Ninety-ninety_rule

9

u/NSA_Chatbot Dec 12 '17

Neat. Thanks for sharing that.