One time about 9 years ago a friend of mine and I got into an argument over what burns out speakers.I told him that it was low power cheap amps that were the culprit.He said it was too much power.Well I had a cheap Aiwa speaker sitting around and decided to prove my point.I took the 5" aiwa (Rated at 30w in the box)driver out of the box and hooked to my 125w ch Kenwood receiver(Long gone)and watched that little Aiwa woofer start to chuff.And as I turned up the volume that speaker started waltzing around the top of my rack.And as I went higher it started to bounce up and down on the rack.We sat and watched this for about 10 minutes.After I took the speaker and showed him that the voicecoil wasn't burnt,in fact it was still aligned!
In the end tho the Aiwa did go,it's magnet wound up on my fridge.
In the end tho the Aiwa did go,it's magnet wound up on my fridge.
Both sides of a bridge-like circuit, fed with 320V DC, became turned on at the same time by accident while powering an highly inductive 230V AC motor.
That's one of the best ways that I've ever seen to migrate copper from one place to another in a PCB
Also, the bang is quite remarkable when 6 TO-220 devices explode at the same time.
An externally hosted image should be here but it was not working when we last tested it.
That's one of the best ways that I've ever seen to migrate copper from one place to another in a PCB
Also, the bang is quite remarkable when 6 TO-220 devices explode at the same time.
Once I was building a large 3 phase invertor... 350 kW (?). This was a special invertor that could also run backwards to charge batteries from a generator.
It had very large IGBT's... somewhat larger than a pack of cigarettes. The controls and methods were complex... our minds were not. We blew up many of these transistors.
The ceilling of the lab was hundreds of conduits. Everytime we would blow a transistor (usually 2) we would have this green gel from the devices spray itself across the ceiling.
We determined the gel was ektoplasm... the same stuff they had to deal with in Ghost-Busters. It was everywhere... very spooky.
It had very large IGBT's... somewhat larger than a pack of cigarettes. The controls and methods were complex... our minds were not. We blew up many of these transistors.
The ceilling of the lab was hundreds of conduits. Everytime we would blow a transistor (usually 2) we would have this green gel from the devices spray itself across the ceiling.
We determined the gel was ektoplasm... the same stuff they had to deal with in Ghost-Busters. It was everywhere... very spooky.
Worst diy project?
i could name so many..
but the perhaps best was when i was around 12ish, and my 14'inchtv had bad reception. the solution?
plug the antenna wire into the amp, and take the signals out the output. looking back i can appreciate the logical problem solution, but my, what a bad idea.
other dumb things? well, i wont even nemption my "tesla coil" experiment.. wait, i'm lying. i have no idea what the voltages were, but two TV 30kv trafos in series spell trouble if you dont really know what your doing. i didn't at the time the coil never worked, and for sme reason i'm still here.
i could name so many..
but the perhaps best was when i was around 12ish, and my 14'inchtv had bad reception. the solution?
plug the antenna wire into the amp, and take the signals out the output. looking back i can appreciate the logical problem solution, but my, what a bad idea.
other dumb things? well, i wont even nemption my "tesla coil" experiment.. wait, i'm lying. i have no idea what the voltages were, but two TV 30kv trafos in series spell trouble if you dont really know what your doing. i didn't at the time
the coil never worked, and for sme reason i'm still here.poobah said:
The ceilling of the lab was hundreds of conduits. Everytime we would blow a transistor (usually 2) we would have this green gel from the devices spray itself across the ceiling.
We determined the gel was ektoplasm... the same stuff they had to deal with in Ghost-Busters. It was everywhere... very spooky.
That gel inside IGBT modules is indeed bit spooky. Lucky for me it has'nt reach the ceiling so far
bakmeel,
This was not a normal invertor... it would run in 2 directions... battery to AC... or generator (AC) back to battery. When external loads on the generator would change severely, the generator would slow down, the invertor (running backwards) would lose synch with generatorand try to "charge" the generator... then BOOM.
Ususally we blew up 2 IGBTS... but sometimes 4 or 6... I think we blew about 20... they were $1200 each.
We worked behind a large Lexan screen! 350kW is ALOT of power!
This was not a normal invertor... it would run in 2 directions... battery to AC... or generator (AC) back to battery. When external loads on the generator would change severely, the generator would slow down, the invertor (running backwards) would lose synch with generatorand try to "charge" the generator... then BOOM.
Ususally we blew up 2 IGBTS... but sometimes 4 or 6... I think we blew about 20... they were $1200 each.
We worked behind a large Lexan screen! 350kW is ALOT of power!
Charging caps
Well, i also was once ~15 years old, having the brain full of bs...
I got hands on a ~220uF cap ~300v, what was more logical to charge it ? So i took a diode, placed it in series with the cap and... placed the open wires in the mains outlet. (of course, where else ?)
It happened what had to happen, the diode exploded in a VERY loud bang... As the experiment had failed (i thought) i cleaned up and took the cap away, with its wires swinging around. Well, the diode lived long enough to put a significant charge into the cap resulting in a big plasma ball where the swinging wires touched. This bang was even louder than the exploding diode and the wires were few cm's shorter...
I guess my heartrate was at record levels.
One year later i got hand on a 12kv/40ma transformer (used for ignition in oil ovens). I wanted to have that rectified and putted 20 1n4007's in series. Hmm, now i needed a cap for finalizing this "PSU", so i took 3 plates of glass around two alum foils, connected all and pushed the plug into the mains...
This was the most frightening experience in my life, the isolation of the cap was not sufficient, giving several discharges per second, resulting in several cm's long sparks, burning my carpet and hurting the ears. I still had a tinitus 10 minutes later...
I wonder that i am still alive... (at least i never again played with charged caps)
Mike
Well, i also was once ~15 years old, having the brain full of bs...
I got hands on a ~220uF cap ~300v, what was more logical to charge it ? So i took a diode, placed it in series with the cap and... placed the open wires in the mains outlet. (of course, where else ?)
It happened what had to happen, the diode exploded in a VERY loud bang... As the experiment had failed (i thought) i cleaned up and took the cap away, with its wires swinging around. Well, the diode lived long enough to put a significant charge into the cap resulting in a big plasma ball where the swinging wires touched. This bang was even louder than the exploding diode and the wires were few cm's shorter...
I guess my heartrate was at record levels.
One year later i got hand on a 12kv/40ma transformer (used for ignition in oil ovens). I wanted to have that rectified and putted 20 1n4007's in series. Hmm, now i needed a cap for finalizing this "PSU", so i took 3 plates of glass around two alum foils, connected all and pushed the plug into the mains...
This was the most frightening experience in my life, the isolation of the cap was not sufficient, giving several discharges per second, resulting in several cm's long sparks, burning my carpet and hurting the ears. I still had a tinitus 10 minutes later...
I wonder that i am still alive... (at least i never again played with charged caps)
Mike
Anyone ever pull (and hold) a spark plug wire off the plug of a running engine? There are better ways to test for spark. A good coil will shoot up to 40,000v. Wakes you up and hard to let go of. It feels worse than reaching across a car battery in a wet shirt. That feels kind of interesting if you can ignore the chest pains. Luckily, I have had few episodes at my electronics bench. Just the typical- every time I build a power supply for something, I short it against any piece of conductive material within 10 feet of my chair. I build nothing that is not fused (in both senses of the word).
Although, nothing wakes up the neighborhood more than lighting a quarter stick of dynamite in the gravel driveway that you share with the neighbors. I did this during a cookout my parents were having. I had to replace all of the glass that blew out on my neighbors garage. A small price to pay.
Although, nothing wakes up the neighborhood more than lighting a quarter stick of dynamite in the gravel driveway that you share with the neighbors. I did this during a cookout my parents were having. I had to replace all of the glass that blew out on my neighbors garage. A small price to pay.
I had a small workshop with only 18" or so between benches. The rear bench had TVs running on soak test, no backs on of course. While repairing a TV on the front bench I managed to touch the A1 supply at the tube neck ~8Kv. My arm shot back and my elbow hit the tube neck of a TV.... my arm shot forward and once again I hit the tube neck of the first TV. My arm shot backwards and my elbow hit the tube neck...and so it went on.
Ever wondered what it's like to be part a pinball machine?
Ever wondered what it's like to be part a pinball machine?
Not actually a "personal stunt", but one I witnessed in high school....
Sitting in study hall one day, with several of the "burnouts" (guess I aged myself with that term), I saw these guys taking gum wrappers (the foil part), forming them into a makeshift "plug", and sticking them into the wall outlets.
After the requisite pop and smoke, the outlets were left with nice burn marks, and I suppose the janatorial staff was curious about the occasional popped breakers.
Weird story, but all I could think of here.
Chris
Sitting in study hall one day, with several of the "burnouts" (guess I aged myself with that term), I saw these guys taking gum wrappers (the foil part), forming them into a makeshift "plug", and sticking them into the wall outlets.
After the requisite pop and smoke, the outlets were left with nice burn marks, and I suppose the janatorial staff was curious about the occasional popped breakers.
Weird story, but all I could think of here.
Chris
My worst project was a TL enclosure.
Armed with the Loudspeaker Cookbook, I set about making a short line(line length reduces with stuffing
)
The design stage over, I was looking forward to beating all the fools who could only manage to make big enclosures.
After construction, I was finally brought down to earth.
To top it all, my normally appreciative wife was present when I tested it. Try harder next time, she said.
Armed with the Loudspeaker Cookbook, I set about making a short line(line length reduces with stuffing
)The design stage over, I was looking forward to beating all the fools who could only manage to make big enclosures.
After construction, I was finally brought down to earth.
To top it all, my normally appreciative wife was present when I tested it. Try harder next time, she said.
here is my stupid diy project:
i was experimenting with various amplifiers on Lowthers, just to get the taste of how they sound on tubes and solid state, I had half a dozen of amplifiers i was testing, when i got an idea to try one big solid state (technics if i remember correctly) in bridged mode, so i unpluged the leads from speakers and connected one of lowthers into other chanel and than pushed the switch
wow, you should hear the bang....there goes one of my Lowthers
i guess it put some significant dc on output
i was experimenting with various amplifiers on Lowthers, just to get the taste of how they sound on tubes and solid state, I had half a dozen of amplifiers i was testing, when i got an idea to try one big solid state (technics if i remember correctly) in bridged mode, so i unpluged the leads from speakers and connected one of lowthers into other chanel and than pushed the switch
wow, you should hear the bang....there goes one of my Lowthers
i guess it put some significant dc on output
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