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What is the most unusual experience you have had with electronics? — Parallax Forums

What is the most unusual experience you have had with electronics?

computer guycomputer guy Posts: 1,113
edited 2012-08-16 01:50 in General Discussion
I am interested to hear the weird and wacky things you guys have experienced when working with electronics.
This might include something happening that you weren't expecting (good or bad).
Or something you learnt that surprised you.

Mine is when I was about 12 and I connected a 5mm red LED up to a 9V battery and the plastic casing of the LED exploded and bits of LED went flying across the room at high speed.
I expected it to light for a bit and burn out, but the results where impressive. :D

Comments

  • jazzedjazzed Posts: 11,803
    edited 2012-08-11 22:17
    Explosions. Yes.

    In 1984 I was working in a US NAVY repair facility in Misawa Japan. My friend liked to pick up boards to test that came from the soldering specialty folks at the start of the day. The previous night someone set an order to have a large electrolytic capacitor replaced in a power supply. My friend started the test procedure and bam! The cap went off like a rocket and hit his horn-rimed standard issue glasses. I'm sure the glasses which were only scratched saved his eye.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-08-11 23:09
    A lesson I learned the hard way: I had designed and installed an RS422-networked inspection and control system for a fruit-packing line. The plant used composite conveyor belts with tinsel to bleed off any charge build-up. That's right: think Van de Graf generator! The charge was still accumulating somewhere, and every time it discharged -- with a resounding SNAP! -- parts of my system would reset. It also didn't help that the plant electricians ran my shielded network cable through the same conduit carrying 400+VAC for the conveyor motors. Well, ignorantly, I had connected the network cable shielding to ground at both ends of each run. That's a big no-no! Shielding that's allowed to carry current is ineffective. Once each drain wire had been clipped from one end, the reset problem and other noise issues went away.

    -Phil
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-08-12 07:30
    Well, I thought cooking a hot dog with 120VAC was about the most weird and wacky that I'd experienced. And I do think it is one of the best ways to cook a hot dog efficiently.

    But when I saw on the Web, a hot dog plugged into 120VAC with about 20 LEDs of various colors blinking on and off due to eddy currents in the cooking hot dog -- that was IT.

    http://meat-recipes.wonderhowto.com/how-to/cook-hot-dog-with-leds-154557/
  • skylightskylight Posts: 1,915
    edited 2012-08-12 09:18
    That's amazing, though are you sure that was a hot dog and not a Chip-olata?
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-08-12 09:41
    You can do the same with a large pickle. But no LEDs required: it glows all on its own.

    -Phil
  • TorTor Posts: 2,010
    edited 2012-08-12 10:02
    First year in my electronics education one guy connected a 220V / 12V transformer to the net and grabbed one of the 12V-ends in each hand. Problem was that he had connected the transformer the wrong way.. the 12V side into 220V AC, so he was holding on to nearly 4000V AC. You mentioned flying LEDs and capacitors.. well, this guy flew straight back several meters. We collected him from the floor and sent him to the nearest ER, although he said he was fine, really.. except that he looked completely confused. He came back to class later in the day but he still looked quite bewildered and mostly just sat there looking at a wall.

    -Tor
  • Martin HodgeMartin Hodge Posts: 1,246
    edited 2012-08-12 13:27
    I once stumbled upon this odd internet forum where a lot of electronics geeks hung out. Most of them seemed to be eerily infatuated with one single micro chip. Almost to the exclusion of everything else. :innocent:
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-08-12 14:01
    Yeah, those guys over at AVRFreaks need to get a life! :)

    -Phil
  • jazzedjazzed Posts: 11,803
    edited 2012-08-12 14:51
    >> ... Almost to the exclusion of everything else.

    LOL!

    If all goes well we'll have another Propeller chip for our infatuation. Otherwise, we may be forced into buying existing excess inventory somewhere else.
  • SRLMSRLM Posts: 5,045
    edited 2012-08-12 16:47
    Unusual, no, but blowing things up seems to be a theme for "interesting":

    I've experimented with different ways of blowing up electrolytic capacitors. It's possible to plug them into 120VAC, and they go pop. I make sure to use an extension chord.

    Back in my inexperienced days (joke!), I tried teaching soldering to some students. Unfortunately, I forgot that I was much better and my tests might not be accurate. I was able to solder the device with no problems: an LED soldered directly to a coin cell lithium battery. The first time I tried it with somebody inexperienced, it exploded and he ran around the room screaming. He was 20 years old, too. Fortunately, nobody was hurt and I don't teach that anymore (now we solder wires: much safer!).
  • localrogerlocalroger Posts: 3,452
    edited 2012-08-12 17:35
    When I was just starting out I used to patrol for discarded TV's and stereos. In the early 1980's these could be real prizes, and one day I found a doozy, a 25-inch console (in that day a monster) with expensive wood cabinet, and then state of the art football-sized remote control. I brought it home, plugged it in, and easily figured out that there was a bad power supply cap, as its problem was heavy ripple on B+.

    Yeah, vacuum tubes.

    I had a pile of parts salvaged from similar TV's and easily found a candidate to replace the bad cap, which was also easy to identify because it was scorched. Of course my cap had come from another old TV, and I wasn't too up on what happens to caps as they age back then... I put it in, turned the set around, turned it on, and high-fived my girl as a nice sharp crisp picture emerged.

    Which held for about 30 seconds.

    At 90 seconds the new capacitor exploded, spraying little bits of capacitor electrolyte soaked paper all over the living room and rocketing the capacitor can right through the wood veneer cabinet.

    I probably could have fixed it but I couldn't afford to order a new capacitor of the right type, and I had to put the set back out on my own curb, where someone else plucked it before the garbage men arrived.
  • Martin HodgeMartin Hodge Posts: 1,246
    edited 2012-08-12 18:17
    Does crazy count? In high school a couple of us made a crude rail gun by connecting a large deflection yoke to a photo-flash capacitor and a big pushbutton. We finally were able to embed small screws in the ceiling tile before we got bored.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-08-13 07:17
    You can do the same with a large pickle. But no LEDs required: it glows all on its own.

    -Phil

    I am really shocked!!!! Are you saying that you can get a glowing pickle by plugging it in to 110VAC?
  • Heater.Heater. Posts: 21,230
    edited 2012-08-13 07:42
    Years ago a friend of mine had a huge electrolytic capacitor in the power supply of the oscilloscope he was building explode. All of a sudden the lab was full of "snow". I always wondered what toxic gunk we we breathing that day.

    Recently I find it spooky that you can get the digits of a 7 segment LCD, as used in calculators etc, to go dark just by grounding one pin and touching a few others whilst holding a power chord in the other hand.
  • prof_brainoprof_braino Posts: 4,313
    edited 2012-08-13 08:24
    Not my story, but that's never stopped me from telling it.

    Our lab had a battery backup system. Think dozens of car batteries (actually deep cycle batteries) connected by fat cables to copper conductors something like 2 x 30 cm several meters long.

    A service tech slipped and touched his wrench to both panels where it welded itself. Another tech in the room swore he saw the shadow of the guy's hand through the copper in the flash that burned it off. Probably not, he probably just knew what was happening and his brain filled in the gory details, but it still scares me from touching big fat copper conductors connected to dozens of deep cycle batteries.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-08-14 01:43
    As a teen, I used to love to read "The Amateur Scientist" projects in Scientific American.

    The one that really caught my attention was a DIY X-ray machine made of an old vacumn tube being abused by an excess of applied voltage. It seems that the X-rays would stream off the top of it and one could then use photographic paper or film in a light excluding sealed envelope to take pictures of dead fish, one's hand, and so on.

    Of course, there were serious hazards of accumulating radiation burns. But in the 1960s, hobbyist were braver and didn't have lawyers willing to sue publishers so easily.
  • OppaErichOppaErich Posts: 48
    edited 2012-08-14 06:30
    The glowing pickle was shown in one of the first 6.002x lessons, that was impressive and funny. I have a phantom problem at home. My dish washer broke some months ago, the rinse pump does not start. So I pulled the plug and let it dry out and now without any power source the 'need salt' indicator lamp is on. :innocent: And I can confirm that electrocution of hot dogs works fine with 230V AC too, about 2 seconds and they're cooking like mad.
  • David BDavid B Posts: 592
    edited 2012-08-14 08:08
    When I was about 5 years old, my brothers and I were excited to learn that if we touched the metal latch of our old dishwasher while standing on a damp kitchen floor, we'd feel a funny buzzing sensation!

    When my father saw what we were doing he almost went into a panic, and pulled out the dishwasher to fix whatever frayed wires were touching the frame.

    But we kids thought it was pretty cool.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2012-08-14 12:24
    Anyone remember the old fuse boxes in houses that had the screw in fuses? I was about 8 years old when I figured out what NOT to do. I unscrewed one of the fuses and stuck my finger in. It sure did not take long to figure out that it was not real smart to do that!!!!!
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2012-08-14 14:27
    Years ago a buddy of mine and I got a hold of a microwave oven transformer.... one of the big ones from an old micro wave oven about a 9 inch cube of a transformer.

    Anyway we were having 'fun' vaporizing just about anything we could find. At some point I managed to get the hot end of it and the next thing me and my buddy remember is picking ourselves up off the ground. From what we can determine, I (electrically induced) backhanded him so hard that it knocked both of us on to the floor from our "bar stool" style bench chairs.

    Another time I had designed a circuit that I called a universal power supply....The current was regulated, and the voltage automatically adjusted to whatever you needed to plug it into without needing to move a slider switch or any of that business... I was rather proud of the design and it worked well for a long time until .... one day I was using it and it sounded like two rifle shots going off in close proximity, One hit my cheek and left a nasty bruise. Turns out the the capacitors rated for 16V had had enough and decided to blow. They were no bigger than my pinkie finger around. ... So much for that design (Sigh)
  • prof_brainoprof_braino Posts: 4,313
    edited 2012-08-14 15:39
    Anyway we were having 'fun' vaporizing just about anything we could find.

    Beau remains my role model
  • HumanoidoHumanoido Posts: 5,770
    edited 2012-08-14 19:59
    The electronics lab was upstairs. One evening, I was downstairs and heard loud noise from some intruder that secretly broke into the lab and was carrying on a conversation... Cautiously approaching the lab revealed a different surprise - the new speech synthesizer circuit was left on and suddenly began chatter. No one knew why it began talking on its own.. but the experience did increase funding, not for door locks but for Artificial Intelligence..
  • piguy101piguy101 Posts: 248
    edited 2012-08-15 12:49
    I was a little confused when I hooked up an infrared LED, forgetting the resistor, and saw the infrared LED light up.
  • CircuitsoftCircuitsoft Posts: 1,166
    edited 2012-08-15 16:36
    piguy101 wrote: »
    I was a little confused when I hooked up an infrared LED, forgetting the resistor, and saw the infrared LED light up.
    Are your eyes still okay? In a dark room you can see the IREDs in the end of a remote, but you really need your eyes used to the dark. To see it in room light means it was really bright and probably didn't cause your irises to constrict.
  • kwinnkwinn Posts: 8,697
    edited 2012-08-15 17:03
    When I was about 3 or 4 years old I saw my Grandfather going around the house with a light bulb with 2 wires sticking out. He would plug them into an electrical outlet and the bulb would light, then he would go on to the next one. I wanted to do it as well so I got a light bulb out of a lamp, wrapped some bare wire around it, and plugged it in to the nearest outlet. When I woke up I was laying several feet away from the outlet, the house was dark, and all I could remember was a really big bright flash, and all I could see was the flash after image. I went and hid under my bed for a while.
  • Heater.Heater. Posts: 21,230
    edited 2012-08-16 01:50
    Ages ago I was surprised to see a board I had just powered up lighting a LED, I had never noticed a LED on the board.
    Turned out to be the chip inside an UV erasable EPROM shining at me through it's quartz window.
    I had plugged that EPROM in backwards and it was glowing red (for a while).
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