In 1980/81 I was studying electronics at Durham, England.
In the morning we did theory and in the afternoons built up circuits to test the theory.
One of the projects was a LM386 amplifier.
There were about 12 of us in the class.
We started building up the pcb and then started testing.
There was a loud crack and a electrolytic capacitor exploded.
Big cheer went up.
About the half the class got the cap the wrong way and exploded it.
Being a smug git I managed not to blow mine up.
After 40 years in electronics I have never blown up an electrolytic cap.
Well until today I finally did it with a 100uf 35v electrolytic.
Obviously not concentrating.
So not so smug now.
In the morning we did theory and in the afternoons built up circuits to test the theory.
One of the projects was a LM386 amplifier.
There were about 12 of us in the class.
We started building up the pcb and then started testing.
There was a loud crack and a electrolytic capacitor exploded.
Big cheer went up.
About the half the class got the cap the wrong way and exploded it.
Being a smug git I managed not to blow mine up.
After 40 years in electronics I have never blown up an electrolytic cap.
Well until today I finally did it with a 100uf 35v electrolytic.
Obviously not concentrating.
So not so smug now.
This is why I now use a remote controlled outlet to turn on gear for testing. I've never had a problem but hey, you never know. I always just stand back. I don't have years of experience doing this stuff and the last person I trust to do things right is myself!
Makes you wonder why in 40y they haven't come up with DC capacitors that could care less about polarity. I guess they like the fireworks, and to keep the supply moving.
First Blowing Up Capacitor is a rite of passage...
First cap I blew up was probably 40 years ago. Welcome to the club. Though I may have tried a time or two to make the blow up happen.
I nearly vented a 2200uf 35v cap on my voltage regulator when I saw no output and my lab PSU went into current limit!
I mean it is reversed...
I mean it is reversed...
Agree on that.
But then comes a 2nd... and a 3rd... and even a few on purpose hahah
:D
My "rite of passage" is dictated by: only one pair of eyes, one pair of hands and only one face!
Getting a permanent debilitating injury, is not a joke. Ask anyone who has been injured by an accident losing an eye, or a finger whether they continue to be entertained by such incidents.
Sorry for the moderation, but this thread gives the wrong message to students.
Getting a permanent debilitating injury, is not a joke. Ask anyone who has been injured by an accident losing an eye, or a finger whether they continue to be entertained by such incidents.
Sorry for the moderation, but this thread gives the wrong message to students.
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I started tinkering with electronics at a young age when nearly everything electronic used tubes. My first electrolytic accident happened around age 10 which was 60 years ago. I had a collection of 4 or 5 AA5 radios that worked which were made from a collection of dozens that I had dragged home and stripped for parts. The typical AA5 radio had a B+ voltage of about 125 to 130 volts from a 35W4 or 35Z5 half wave rectifier on line voltage which was about 115 volts then.
I learned from a library book (remember them) that "diodes" were more efficient than tubes, so I wired a diode of unknown origin in place of the 35W4 tube and fired the radio up. Even then I had a remote power switch for my entire bench. It was an exposed light switch and duplex outlet mounted on some plywood, but that seemed acceptable in the early 60's. The electrolytic in the radio was one of those old paper cylinders with four wires sticking out of one end. It shot a mixture of fire and molten "stuff" out of the wireless end burning my new workbench which was made from an old closet door.
Sometime in the late 70's I got a box of 470 uF 50 V caps from a local surplus outlet. Note the 1974 date code and the country of origin. These turned out to be total junk so most turned out to be remote firecrackers on the end of an extension cord. While digging through some of my old stuff I just found 5 more. They went into the trash.
Note that most current vintage electrolytics will just vent stinky steam and a nasty goo if reversed or otherwise violated. An extreme overload will still make them explode. A DUMM BLONDE moment while repairing several dozen PC power supplies left fragments of an electrolytic can embedded in the ceiling of my workroom in the Florida house. I adopted the dim bulb tester methodology on the very next power supply I fixed.
Attachments
There are old pilots and bold pilots, but there are no old bold pilots.
Hope it wasn’t hard to clean up…
I did that once in a small room, still remember the piercing echo from that thing, had metal end caps!
I did that once in a small room, still remember the piercing echo from that thing, had metal end caps!
Caps are not the only things that blow up. I had the ground lead of a scope probe explode in the lab at college. There was a power strip on front edge of the shelf for all the test gear and it seems one plug was not fully inserted so the prongs were slightly exposed, and I hadn't noticed - yet. As I picked up the probe the ground lead dangled down, touched the hot prong and instantly vaporized with a bang like a shotgun. The professor nearly had a heart attack and my ears rang for days. Now I consider myself very lucky since I only got a small burn on my hand. Safety glasses were not used in those places in the 70's and flying bits of molten copper aren't good for the eyes. If you don't already have safety glasses, get them, wear them, and you won't be sorry.
I recently had an electrolytic vent messily. It appeared to be the right way round, but I suspect it was a fake
My first exploded caps were the intentional ones. When you get a grab bag of caps there are usually sone duds - maybe not nonworking, but a “what am I going to DO with a three (or 6.3) volt cap?” cap. It will blow up if you put any real voltage on it, so why not help it along with 25.2 VAC? Ones that would have otherwise exploded were prevented from doing so by a dim bulb. They just get hot and sizzle a bit.
It was exploding diodes for me. Plug it in, output transistors (T0-3 germanium) short. Power supply diodes are the first to go. It was plugged in at the end of a 50’ extension cord. The next amplifier got plugged in on a dim bulb.
The worst were exploding hexfets. TO-247’s in a DC/DC converter running off a car battery. I was within 2 feet of it when it went.
It was exploding diodes for me. Plug it in, output transistors (T0-3 germanium) short. Power supply diodes are the first to go. It was plugged in at the end of a 50’ extension cord. The next amplifier got plugged in on a dim bulb.
The worst were exploding hexfets. TO-247’s in a DC/DC converter running off a car battery. I was within 2 feet of it when it went.
Some time ago, my colleague brought her 10 year old daughter into work. When it came to my turn to entertain her, we invented the Great Capacitor Race, in which we series-connected half a dozen capacitors mounted on a piece of cardboard and named each one after a colleague. We then connected a hefty power supply, reverse polarity, and waited...
The first one to go bang scooped the prize.
My colleague's daughter went on to a career in electronics (having shown no interest previously) and is currently enjoying working as a technical author.
I like to think that in some small way I have given something back to Society.
The first one to go bang scooped the prize.
My colleague's daughter went on to a career in electronics (having shown no interest previously) and is currently enjoying working as a technical author.
I like to think that in some small way I have given something back to Society.
I was blowin caps up back in '72.
In '81, I started work at General Instrument as a QA/Test engineer. One part was testing customer returns for validity of rejection.
Turned out, sometimes diodes were marked backwards. But even that cause did not put the diodes in the garbage. They put them into a 50 gallon drum of rejects, purchased by entities like Radio Shack for rebranding/repackaging.
jn
In '81, I started work at General Instrument as a QA/Test engineer. One part was testing customer returns for validity of rejection.
Turned out, sometimes diodes were marked backwards. But even that cause did not put the diodes in the garbage. They put them into a 50 gallon drum of rejects, purchased by entities like Radio Shack for rebranding/repackaging.
jn
I was a Mr. Fixit for the entire Motorola two way radio and radio subassembly factory from 1974 to 1984. I pushed my crash cart around the factory and was responsible for keeping anything related to test and measurement operational in that factory on the 3:30 PM to sometime after midnight shift. I was on call via telephone and pager 24/7.
We had a pair of 1970's vintage automated test systems for final testing of all MX-300 two way radio products, aptly called Bigfoot 1 and Bigfoot 2. These were large primitive systems using rack mounted HP equipment and computer systems. They were pretty reliable, but the computer would lose its mind every day or so and require a 5 minute reboot. The factory was in south Florida which is the lightning capital of the US, so there was a giant rack mounted UPS system that kept both Bigfoots fed their daily electricity requirements. The MX-300 factory ran 24/7, but was not at full capacity from midnight to 7:30 AM, so no live support was furnished. Once a month or so I would get called in during the night to reboot Bigfoot, for which I got 4 hours pay. Total two way drive time plus reboot time was about an hour, so I didn't mind.
I got a panic distress call one night about 4 AM. I heard a lot of people yelling things like "it's on fire" or "it exploded" so it meant get here now! I hopped in my van and got to the plant to find pieces of that industrial strength UPS scattered all over the place. The thing filled an entire 6 foot tall 19 inch equipment rack and had to be moved by fork lift. I never knew what was inside it, since it always worked. Well, now the insides were all over the place, and at least two of the lead acid batteries had ruptured. A large electrolytic cap had exploded blowing the side off the UPS also taking out a file cabinet that sat next to it.
I rewired the Bigfoots to run directly on raw line power got them up and running, picked up everything that was part of that UPS, called in a facilities maintenance guy for a clean-up, and waited for the factory and lab bosses to arrive since it was almost 7 AM.
The company that made the huge UPS was called in, and they replaced the entire machine with one of their newer models. From what I saw and what I learned from the tech-rep from the UPS company, there were two quart sized electrolytic caps wired directly across 84 volts worth of golf cart or marine batteries. One cap shorted and exploded likely setting off some of the hydrogen gas released by the batteries since the battery compartment was mangled. A lot of finger pointing occurred since there was a maintenance schedule for this thing which was never followed. Several of the intact batteries were quite low on water.
I have seen those old quart sized can caps vent, but never explode. That thing had some serious destructive power.
We had a pair of 1970's vintage automated test systems for final testing of all MX-300 two way radio products, aptly called Bigfoot 1 and Bigfoot 2. These were large primitive systems using rack mounted HP equipment and computer systems. They were pretty reliable, but the computer would lose its mind every day or so and require a 5 minute reboot. The factory was in south Florida which is the lightning capital of the US, so there was a giant rack mounted UPS system that kept both Bigfoots fed their daily electricity requirements. The MX-300 factory ran 24/7, but was not at full capacity from midnight to 7:30 AM, so no live support was furnished. Once a month or so I would get called in during the night to reboot Bigfoot, for which I got 4 hours pay. Total two way drive time plus reboot time was about an hour, so I didn't mind.
I got a panic distress call one night about 4 AM. I heard a lot of people yelling things like "it's on fire" or "it exploded" so it meant get here now! I hopped in my van and got to the plant to find pieces of that industrial strength UPS scattered all over the place. The thing filled an entire 6 foot tall 19 inch equipment rack and had to be moved by fork lift. I never knew what was inside it, since it always worked. Well, now the insides were all over the place, and at least two of the lead acid batteries had ruptured. A large electrolytic cap had exploded blowing the side off the UPS also taking out a file cabinet that sat next to it.
I rewired the Bigfoots to run directly on raw line power got them up and running, picked up everything that was part of that UPS, called in a facilities maintenance guy for a clean-up, and waited for the factory and lab bosses to arrive since it was almost 7 AM.
The company that made the huge UPS was called in, and they replaced the entire machine with one of their newer models. From what I saw and what I learned from the tech-rep from the UPS company, there were two quart sized electrolytic caps wired directly across 84 volts worth of golf cart or marine batteries. One cap shorted and exploded likely setting off some of the hydrogen gas released by the batteries since the battery compartment was mangled. A lot of finger pointing occurred since there was a maintenance schedule for this thing which was never followed. Several of the intact batteries were quite low on water.
I have seen those old quart sized can caps vent, but never explode. That thing had some serious destructive power.