First valve pre amp.
Turned it off and touched circuit and got a belt.
Tutor told me to discharge capacitor before touching circuit.
So next time discharged capacitor, touched circuit and got another belt.
Had for gotten to turn it off !!
Spent an hour trying to find out why my amp oscillated.
Turned out my overhead CFL lamp was interfering with it !
Spent half an hour trying to work out I was only getting 5 volts out of my amp instead of 50. Turned out scope problem was on *10 !
Doh !
Turned it off and touched circuit and got a belt.
Tutor told me to discharge capacitor before touching circuit.
So next time discharged capacitor, touched circuit and got another belt.
Had for gotten to turn it off !!
Spent an hour trying to find out why my amp oscillated.
Turned out my overhead CFL lamp was interfering with it !
Spent half an hour trying to work out I was only getting 5 volts out of my amp instead of 50. Turned out scope problem was on *10 !
Doh !
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Working on an old TV (when I was 17) I had picked up along the road.
I reached up and unplugged the power cord, put my left hand on the chassis and with a set of uninsulated wire cutters, proceeded to start cutting wires.
Woke up in a slump against the opposite wall of the garage.
I had unplugged the soldering iron.
I reached up and unplugged the power cord, put my left hand on the chassis and with a set of uninsulated wire cutters, proceeded to start cutting wires.
Woke up in a slump against the opposite wall of the garage.
I had unplugged the soldering iron.
When I was 16, I bought an HH Scott LK48 amp kit. After assembly, I turned it on and an output tube had a brilliant shower of sparks inside. I took it to a repair shop and the tech found I'd installed an internal cap backwards. Embarrassing. But hey, I'd wired everything else perfectly - lots of parts in that baby - and it was my first big electronics assembly project.
Having made it to age 65 with all of my body parts pretty much intact and still functioning guarantees several "stupid human tricks" stories, and yes, many of them do involve electricity. There were still parts of an electrolytic cap stuck in the ceiling of my Florida house when I sold it.
By far the dummmest thing I have ever done involved working on a car and electricity was the "spark" but stupidity and carelessness ruled the scene. I had to be 18 or 19 years old. I had purchased a 1965 Pontiac Grand Prix for the sum of $200.
The car ran all right most of the time, but had some drivability issues in hot weather so I decided to rebuild the carburetor. Upon removing all the bolts I found that the carb was stuck to the intake manifold. Hammers, screwdrivers, a chisel and anything else I could find were called into action and the carb was finally freed from the manifold. A previous owner had soaked the carb gasket in gasket sealer (not usually done).
Now I had a sticky mess on the manifold, so what does a kid do? He decides the proper course of action would involve a can of gasoline and a paint scraper. Old timers may remember that gasoline cans in the 1960's were made of steel, usually adorned with red and sometimes yellow paint.
So I set out to scrape the remains of gasket and sealer from the intake manifold by liberally applying gasoline to the affected area, and most of the surroundings, and scraping. I was about halfway through the job when IT happened.
I had poured some gas all over the top of the engine and reached over to set the gas can on the fan shroud, and BOOM. There was a flash of light, and instantly my world including myself was on FIRE. I had set the steel gas can on the car's battery. Instinct took over and I did what everyone says NOT to do.....I RAN. Good choice. I must have made the 75 feet or so from the car to the lake in about 3 milliseconds. After the quenching effect had sunken in and I realized that I was still alive and functioning, I saw the fireball in the front yard that was my car.
DUMM mistake #2. I attempted to put out the fire with a garden hose. This accomplished the task of washing liquid fire down much of the yard and into the street. It took me a minute or two to realize that the fire had melted the underhood wiring harness into a shorted out mess of sparking and smoking wires that was preventing me from killing the fire, so the ground wire from the battery was cut with a bolt cutter. I eventually killed the fire with water and dirt. Other than some minor burns, the loss of most of my hair, and a gash in my leg (no clue how), I was not severely hurt.
I fully expected to incur the wrath of my father who usually never missed the chance to tell me what a failure I was, but he seemed rather subdued on this one. He said that he would have the car towed away, but I insisted that I was going to fix it. He gave me a month.....it took almost 3 but I would have it running again.
Mechanically it ran better since the carb, manifold or the gasket sealer was the problem since I replaced them all. Using about 37 rolls of electrical tape, and everything from speaker wire (really!) to house wire I had created enough of a wiring harness for the essentials to function (power train, air conditioning, and quadraphonic 8 track player). The vacuum hoses were another matter. The AC vents were all vacuum controlled, so I just wired them all open. No need for a heater in Miami Florida, so it got ditched.
In retrospect it would have been better to have let my father tow it away, since a drunk in a Cadillac would run a red light and T-bone me in the passenger door, then flee the scene a few months later. That sent my second car to the junkyard. My first would get fixed, and live on until the 1990's when I traded my 1949 Plymouth for an old Scott tube amp.....that got me back to tinkering with tubes, and we all know what havoc I can create with those!
By far the dummmest thing I have ever done involved working on a car and electricity was the "spark" but stupidity and carelessness ruled the scene. I had to be 18 or 19 years old. I had purchased a 1965 Pontiac Grand Prix for the sum of $200.
The car ran all right most of the time, but had some drivability issues in hot weather so I decided to rebuild the carburetor. Upon removing all the bolts I found that the carb was stuck to the intake manifold. Hammers, screwdrivers, a chisel and anything else I could find were called into action and the carb was finally freed from the manifold. A previous owner had soaked the carb gasket in gasket sealer (not usually done).
Now I had a sticky mess on the manifold, so what does a kid do? He decides the proper course of action would involve a can of gasoline and a paint scraper. Old timers may remember that gasoline cans in the 1960's were made of steel, usually adorned with red and sometimes yellow paint.
So I set out to scrape the remains of gasket and sealer from the intake manifold by liberally applying gasoline to the affected area, and most of the surroundings, and scraping. I was about halfway through the job when IT happened.
I had poured some gas all over the top of the engine and reached over to set the gas can on the fan shroud, and BOOM. There was a flash of light, and instantly my world including myself was on FIRE. I had set the steel gas can on the car's battery. Instinct took over and I did what everyone says NOT to do.....I RAN. Good choice. I must have made the 75 feet or so from the car to the lake in about 3 milliseconds. After the quenching effect had sunken in and I realized that I was still alive and functioning, I saw the fireball in the front yard that was my car.
DUMM mistake #2. I attempted to put out the fire with a garden hose. This accomplished the task of washing liquid fire down much of the yard and into the street. It took me a minute or two to realize that the fire had melted the underhood wiring harness into a shorted out mess of sparking and smoking wires that was preventing me from killing the fire, so the ground wire from the battery was cut with a bolt cutter. I eventually killed the fire with water and dirt. Other than some minor burns, the loss of most of my hair, and a gash in my leg (no clue how), I was not severely hurt.
I fully expected to incur the wrath of my father who usually never missed the chance to tell me what a failure I was, but he seemed rather subdued on this one. He said that he would have the car towed away, but I insisted that I was going to fix it. He gave me a month.....it took almost 3 but I would have it running again.
Mechanically it ran better since the carb, manifold or the gasket sealer was the problem since I replaced them all. Using about 37 rolls of electrical tape, and everything from speaker wire (really!) to house wire I had created enough of a wiring harness for the essentials to function (power train, air conditioning, and quadraphonic 8 track player). The vacuum hoses were another matter. The AC vents were all vacuum controlled, so I just wired them all open. No need for a heater in Miami Florida, so it got ditched.
In retrospect it would have been better to have let my father tow it away, since a drunk in a Cadillac would run a red light and T-bone me in the passenger door, then flee the scene a few months later. That sent my second car to the junkyard. My first would get fixed, and live on until the 1990's when I traded my 1949 Plymouth for an old Scott tube amp.....that got me back to tinkering with tubes, and we all know what havoc I can create with those!
I was testing a large power amp that was only delivering half the wave in one channel. I had it powered up with no protection whatsoever (should have had a light bulb in series with the mains but I didn't) and was poking around measuring voltages in the driver circuit when POW! one of the big Sanken output transistors blew up in a bolt of lightening. The case was vaporized around the emitter and the emitter lead stood on the circuit board apart from what was left of the transistor. I was pretty sure I hadn't slipped with the test leads (I was nervous because the voltages were high). A little investigation revealed that all of the driver transistors had desoldered themselves from the board, and the board was heat damaged too. I was able to pull 3 of the 4 driver transistors right out of the board, like loose teeth, with zero desoldering. One of the channels was still working like this! But after my ham fisted foray, 3 of the 4 didn't pass basic test. Only one Sanken survived too. I still wonder if I had reflowed the solder if it would have worked but I'll never know.
I have a couple of runners up too; even more stupid, but less destructive.
I have a couple of runners up too; even more stupid, but less destructive.
In my teen years, I was trying to build a bootleg radio transmitter with some big tubes. Got a schematic for a (tube) regulated power supply of something like 500V and built it. Transmitter of course didn't work, so I turned the homebrew supply on its side and started probing inside. And woke up on the floor.
It all went into the trash (so my dad wouldn't find I was trying to make an illegal transmitter!).
It all went into the trash (so my dad wouldn't find I was trying to make an illegal transmitter!).
actually, that was the sanest thing I've ever done - although after 45yrs she might be questioning it
the list of my own daftmanship is longer than I can remember
Cut myself and badly. 36 years ago on July 4th.
I was using a 6" razor scraper. I placed it handle down inside the scaffold post and did not put the safety cover on. I swung around and drew my arm across it. I made quite a mess and I also had to use that arm to climb down the scaffold. 42 stitches later I was ready for prime time. Unfortunately it's on my left wrist, so being right handed, I do get some questioning looks.
I was using a 6" razor scraper. I placed it handle down inside the scaffold post and did not put the safety cover on. I swung around and drew my arm across it. I made quite a mess and I also had to use that arm to climb down the scaffold. 42 stitches later I was ready for prime time. Unfortunately it's on my left wrist, so being right handed, I do get some questioning looks.
A 150 kW precision magnet power supply was supposed to loaded on a ship the next day on its way to China. Unfortunately, there was a mysterious oscillation that had to be found and fixed before it could be sent off. Working on it with access panels removed, I stood up and turned around with a screwdriver in my hand, just as there was a loud bang and everything went black. A few seconds passed and I realized it wasn't just dark, I was blind. As I started to think about what that meant, shadows started to gradually return, then fade to gray, and finally I could see again. However, all the lights were out in the building and people were looking around to see what happened. Someone asked me if I was alright and I said yes.
Turned out my screwdriver brushed across 2 phases of a 480 vac 3-phase circuit breaker that was immediately above the open access panel where I had been working. Besides blowing that breaker, the arc blew two 10,000 amp breakers feeding the building. About then a very angry secretary came along to tell me she lost a document she had been working on for hours with an old word processor. (this was maybe 40 years ago).
After letting everything that happened sink in and resolving to never allow myself to think about problem solving over planning and executing procedures for safety first and foremost, I went back to work and found the problem -- a ground loop. The supply shipped out working fine the next day. Never forgot that one though. Use it as a reminder still.
Turned out my screwdriver brushed across 2 phases of a 480 vac 3-phase circuit breaker that was immediately above the open access panel where I had been working. Besides blowing that breaker, the arc blew two 10,000 amp breakers feeding the building. About then a very angry secretary came along to tell me she lost a document she had been working on for hours with an old word processor. (this was maybe 40 years ago).
After letting everything that happened sink in and resolving to never allow myself to think about problem solving over planning and executing procedures for safety first and foremost, I went back to work and found the problem -- a ground loop. The supply shipped out working fine the next day. Never forgot that one though. Use it as a reminder still.
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Let's just say that my big transmitter project happened in the same year as the Smokey and the Bandit movie, and could have been used in a legal manner. It used a 4-400 tube on somewhere north of 4000 volts. The device scared me silly and I refused to operate it since a blue flash of ionized air often occurred in the plate tune capacitor when tuning up, or giving a loud scream into the microphone. This thing made about 1200 watts and the tube glowed like it was going to explode....but never did. I gave that beast to a friend who did use it.
At the same time I helped a friend put a Gates HFL-3000 on the air. The amplifier was originally intended for use on 3 phase power, so I told him to find a 7000 volt 1 amp power transformer that would operate from 240 volts single phase. After wiring everything up and powering the beast with a pair of automotive jumper cables into the breaker box, we hit the switch. After all the motors (auto tune) stopped humming the plate transformer relay went clack and the warehouse went dark. We had blown the 100 amp main breaker.
After we had lights I had assumed that there was a big short on the secondary side of that file cabinet sized plate transformer, so I was all over that thing checking my wiring. I couldn't find anything obvious, so I grabbed a Simpson 260, set it to OHMS RX1, and went looking for a short. When I touched the probe to the gallon paint can sized capacitor in the power supply the Simpson EXPLODED. After all the WTF moments we decided to leave for the day.
A day later I figured out that one of the 6 diodes in the original 3 phase bridge was shorted AND one of the 6 series connected bleeder resistors was open. After discharging every capacitor in the unit we tested every part in the plate circuit, but no more dead parts could be found. The Gates went live and got used far too often. I preferred that it not be used whenever I was there.
The pictures look a bit dated, but it WAS 1977. Oh yeah, there was a little transmitter in the trunk of the Road Runner too. You can barely make out me holding up a fluorescent tube near the antenna. It's lit without wires.
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Holy crap!
Worst thing I've done in recent memory was power up a 900w ATX power supply with corroded pins on the ATX connector going to the motherboard.
It smelt for a while. 72 amps available on the 12v rail will do that.
Back in my younger teenage days as the curious guy I was I used to visit the trash room looking for scrapped home appliances, one day found a TV and popped out a nice BU208, built an electric breaker for a spare ignition coil I had which turned out pretty well, running it on the desk with function generator feeding the circuit got 30+ mm nice smacking blue sparks equaling ~30kV flashing out from the center plug arching over to a short wire screwed onto one of the coils terminals.
I had left the coil going unattended but of some reason bent away the wire so there was no sign the coil was in use, the generator was set on a pretty low frequency ~5 Hz charging the coil maximally so there was only a very faint ticking sound coming from the coil, returning back a while later had forgotten it was still running and accidentally stroked my fingers over the center plug and got one of a kind life experience.
Some year later got my driving license and my first car where I installed it successfully.
I had left the coil going unattended but of some reason bent away the wire so there was no sign the coil was in use, the generator was set on a pretty low frequency ~5 Hz charging the coil maximally so there was only a very faint ticking sound coming from the coil, returning back a while later had forgotten it was still running and accidentally stroked my fingers over the center plug and got one of a kind life experience.
Some year later got my driving license and my first car where I installed it successfully.
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