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Stupidest Mistake

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Thomas W

Tue Apr 03 2012, 08:25PM

Registered Member #3324 Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276

Well, i was trying to run a large transformer, i had it balasted and all going through a din rail terminal block, it kept blowing the fuses, i checked the circuit over and tried again, and it blew the fuse, i tryed 5 more times with various alterations and new fuses, then i had a look at the din terminal... it turns out it was a bus type for connecting multiple wires together >.<

whats your stupidest/ worst mistake in electronics?

Steve Conner

Tue Apr 03 2012, 08:45PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Oh, I've made a lot so I'll just pick one at random.

Years ago I borrowed an ancient KW2000 ham radio rig. I wanted to test the transmitter and I knew that required a dummy load. I didn't have one, so I poked a 51 ohm resistor into the antenna socket.

I wasn't expecting much from the power tube as the previous owner, having even less of a clue than I did about how to tune it, had melted a hole clean through its anode. But as I fiddled with the controls it suddenly began to put out about 40 watts. The 2 watt resistor puffed smoke, ejected itself from the antenna socket and burnt a big hole in the carpet.

Forty

Tue Apr 03 2012, 09:40PM

Registered Member #3888 Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649

I used a full bridge of EBC pinout transistors in place of ECB. That's how you fry 140v transistors with only 16v.
need to make one of these

2Spoons

Tue Apr 03 2012, 10:35PM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615

Accidentally applying 12V to the reset pin of a $120 micro controller. >POP<

Ben Solon

Wed Apr 04 2012, 12:43AM

Registered Member #3900 Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600

shorting the + pin of a boost converter cap into the 5v breadboard rail powered by a 60$ arduino.

Patrick

Wed Apr 04 2012, 01:06AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

In high school about 97', I was a sophmore. I had a really nice 288VA NST 12kv, and was running an ion lifter device (DeSeversky type) and there was about 30 feet of +6kv and -6kv wire on an insulated table. The kids then had a bad habit of leaving backpacks in the aisle ways of the lab class. When my professor walked up he tripped, and put his hands out to stop his fall, as would be expected. Now there was that 30 feet of HV wire with one uninsulated section, about a 1/2 inch long.

So of course a purple flame jumped a 1/4 inch to my professors finger, he jumped back muttering and gasping for breath. I was sure I had just killed him. But he was fine, not even mad at me.

That High School teacher was Mr. Tony Aweeka, I didnt know it then, but he would go on to be the most important of my high school teachers, and he was the reason I graduated HS and went on to college.

Conundrum

Thu Apr 05 2012, 07:34AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

ooops.
I was once drawing arcs from a homemade 6 CCFL driver.
Stupidly I'd previously blown half the transistors with a reverse polarity oops, but all 6 were now working.
Slipped, and for the 0.3 seconds before I released the idiot switch (I'm learning!) got the upside of 2.5KV@$DEITYknows howmanymA arm to arm.
FFFFFZZZZUUUZZZZZTTT!!!

Nuff said. Took an hour for the tingling to stop, and had a hell of a time steering my pushbike later that evening.
Alcohol didn't help, BAD idea.
-A

Tetris

Thu Apr 05 2012, 03:40PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

About a year ago, I didn't know anything much about electricity. Salvatore (AKA juniortore1) told me a cool thing to do with a TV... I'm in class right now and she just gave an assignment, I'll finish this when I get home.

Edit:

Ok, so he told me how to make sparks with a CRT. I taped aluminum foil to the screen, and had a little metal ruler. These sparks did not hurt, I barely felt them. However, this one day, I did not have tape (I think the tape was failing). The little power button on the TV fell off, so it's either touch 110V with your pinkie (another accident) or use the plug. It does not have a grounding pin. I figured if it did, i would be dead, or would have been hospitalized for being knocked out. Anyways, I had (in a n00b phase, I didn't know anything about capacitors except for how an average lytic looks like) then held the foil on the screen completely with one hand, and pulled the plug with the other. This was highly tingly and very, very, very nearly knocked me out. I think it did something to my brain; after that, my personality sort of changed. I also became a little more scared than one should with capacitors. Of course, I will be more careful in the future with HV...

AndrewM

Thu Apr 05 2012, 04:14PM

Registered Member #49 Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362

When I was a senior in high school I used to charge up camera flash capacitors and then toss them to people during class. They would invariably reach out and catch them.

... heeeheee. I may be old enough to realize it was stupid, now, but its also still funny.

Hehehehe. Oh poor Pete Pioli... I can still remember him going redfaced in Calculus trying not to shout. Haha.

Hon1nbo

Thu Apr 05 2012, 04:51PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042

In my senior year of high school, when I was working on my underwater ROV project, I was assemblying the propulsion drive board in the physics lab since I had nothing better to do for the circuit sections of the class (the teacher knew this, I even arranged demos and in the past have helped teach the class).
I had just soldered all of the power transistors, optoisolators, and was ready to do a test.I powered it on, and circuit board smoked a bit and the fuse on the SLA blew.
I started probing around a bit and it seemed that every component lead of every component was shorted to itself somehow.
As baffled as I was I somehow managed to get the right idea of what to check. I took a magnifying glass to the PCB: every hole was connected to every other hole through a grid of very small traces that I had not noticed. The traces were lacquered which did not help me take heed of them.

I had to desolder and test every part before getting a new piece of perfboard.

-Jimmy

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