LOL - Exploded cap.

Ahaa, those good ol' pre-1960 murderboxes :smiley: They definitely don't make 'em like they used to.

I've had a few electrolytics pop in my time with electronics. First I had a power supply with a shorted pass transistor (linear regulator) and hooked up an old car clock. After trying to get it to work (not thinking of an overvoltage problem) the electrolytic popped. Second incident was with a power inverter. Plugged it in and the cheap capacitor popped immediately. I was lucky that they were enclosed in a device at the time as the first one definitely would have gone flying.

cjdelphi:
I have a circuit that powers a 11watt fluro tube from 12v, so i decided to have some fun and ramped it up to 16v, 20v, kept turning to max out this step up voltage regulator and i was starting to hit around 25volts
and BANG!!!!, the input capacitor exploded the whole house heard it, it was a 16v 10uf or pf, not sure, i replaced it with a 100pf 25v cap and cranked up the voltage to 22 volts getting a spark gap of around 6cm :smiley: but anyway whatever happened it knocked out my computer (not even on the same circuit) reset my arduino (Which shared the same battery) something weird happened just before or just after huge amounts of energy for a brief moment was consumed my voltage regulator could not care less it seems must have spiked over 6amps which it was happy with, shame the voltage regulator powering the arduino could say the same, and as for why my computer died (power on, screen off) usb is not connected there's no shared link, it's isolated, but it was enough to make the arduino go spastic and tell me there's a power out (located about 1 meter away).

as for the bang, it's deafening not nice .... but sure was FUN!!!!

In high school (1970's) I once "plugged" several large (1000 uF) electrolytic caps into the outlets in the school metal shop. They shut off the circuit breakers at the end of the day, so the caps sat there until the next morning.

Next morning when the instructor turned on the breakers, all the caps exploded in a shower of paper shreds and smoking electrolyte oil!

Nobody ever found out who did it.........

krupski,

I hope your teacher catches you now that you confessed. On the other side of the fence, a retired colleague of mine used to charge up a large capacitor, realizing some of his students has fallen asleep during lecture, then discharged it with a metal piece. The loud bang woke up everyone, very angry. That's how he got back at the sleepers. I bet he'd use a ruler to slap them if they still allowed that. Waste of money, I say, to sleep in a classroom.

liudr:
krupski,

I hope your teacher catches you now that you confessed. On the other side of the fence, a retired colleague of mine used to charge up a large capacitor, realizing some of his students has fallen asleep during lecture, then discharged it with a metal piece. The loud bang woke up everyone, very angry. That's how he got back at the sleepers. I bet he'd use a ruler to slap them if they still allowed that. Waste of money, I say, to sleep in a classroom.

The priests just used to throw erasers at us. And we had to wear dark sports jackets to class...

Many years ago there was a trick played on Noob television technicians by the "Crew". The thing was to charge a 40uF cap to 200 - 400 V and carefully fold the wires (axial lead part) back to the capacitor body and then yell to the Noob "Here Catch" and toss the part at the noob. The practice came to an end one day when the guy that caught the "hot" one took the guy that made it and threw it outside and thrashed him severely. I'd have done the same If I had caught one... but I was aware of the practice... The sweeper filled me in first..

Bob

What's really fun is to charge a cap to like 200v, then "taze" unexpecting friends lmao

That's Exactly what was going on... the real difference was asking the person to "Taze" them selves by saying "Here, Catch". Still was a mean trick and potentiallly very dangerous as there is a Lot of energy in a 40uF cap charged to 250 - 300 VDC at least 2 orders of magnitude greater than the Tazer...

Bob

Lol I musta posted that just after you did, didn't see that, it is quite funny, and it is cool how much energy the cap can disharge at once, I used a large cap charged to 200v to help me "safely " blow out the filament of a car bulb that I was going to use for a sort of neon lamp but just without the neon

winner10920:
Lol I musta posted that just after you did, didn't see that, it is quite funny, and it is cool how much energy the cap can disharge at once

If you put a screwdriver across that big capacitor in the photo the discharge welds it to the screw terminals. You can pick the capacitor up with the screwdriver...

Yeah but it is Hell on the screwdriver ... Gotta re-file the end to make it work right again. BTW I DO know what it is to be tazed, I've done it once or twice...
Back when TV's had tubes if the service tech couldn't fix it by replacing tubes, power supply diodes, circuit breaker and or cleaning the tuner (Big rotary switch), Drum type that actually switched RF, OSC and Mixer coils for each channel... Really Terrible with the Smog present at that time. The Chassis had to go to the shop and in the shop was connected to a test jig that was a CRT, deflection yoke and convergence yoke to replace the one in the house... If one forgot to connect the CRT ground lead you could pull a 1 inch spark to the unlucky fingertip(s)... and If one had the misfortune to have to work on an "OLD" Color set (The really early Color sets had a metal bell that was 3/4 of the CRT and it was connected to the HV supply (25 to 35 KV or more if the regulator failed) one had a "Snappy" experience. I oncxe left a picture tube on the floor in a house where I was in the process of replacing the tube and the customers dog sniffed at the 2nd anode button... Poor dog Never would come near me again. One only did that once... Perhaps twice if you were in a hurry or a slow learner. It IS dangerous to discharge a Really Large capacitor with a screwdriver. I had a "Spark" land on my head once, really burned and it was years before I realized that it might have been my eye except for luck and glasses. I shed the glasses when I got cataracts so I don't play any more.

Bob

Docedison:
I don't play any more.

I only play with things that don't explode and can be switched on from a distance, eg. neon power supplies.

When I was young those things could be had for the trouble of dragging them home, I've made everything from room ionizers to rotary gap spark transmitters (Wiki that you'll be surprised). I had a "little Red Wagon" and a rope tether to tie it to my bicycle... My favorite things were discarded television chassis (s)... (SP?) there were literally hundreds of parts for the trouble of removing them and sorting them, I used Egg boxes for parts storage. I made my first AM 'Phone transmitter with a sweep tube a power transformer and a smaller B&W TV chassis ans a Heathkit (Anyone remember Them?) W5M Power amp as the Heising modulator (with a matching transformer) on a good day when the line voltage was about 125 Volts I could get 25 watts of power @ 80 and 160 meter wave length's and I had a 50 meter long Zepp fed transmit antenna... Worked great. I still am a Licensed Amateur Radio operator with the call sign WA7EMS... and I chose that vanity call for 2 reasons, it was my "Bootleg" call sign for many years also the phonetics are... interesting.

Bob

Worked great. I still am a Licensed Amateur Radio operator with the call sign WA7EMS

It looks like your license expired in June, 2012.

Man I wish things like that were still laying around waiting to be taken, most tv sets I find(tubes that actually still have the coils that weren't hacked apart for scrap already) the parts I find are in horrible shape, and most times don't work
the best I find these days is power supply boards because most newer electronics have a separate board for the supply,
and unfortunetly in modern tvs the only high voltage parts is the fluorescent tube lighting supply, which some actually have served me well for some experiments, but still I wish I were able to find something with vacuum tubes and all the cool older technology, some reason while it seems harder and more complex to work with a vacuum tube just strikes me as more interesting than a little black transistor lol
the coolest older tech I got is a 1985 40x2 VFD which I figured out how to write to, which is kinda funny since its like 8 years older than me

winner10920:
40x2 VFD which I figured out how to write to, which is kinda funny since its like 8 years older than me

A VFD is a type of vacuum tube triode.

Man I wish things like that were still laying around waiting to be taken

You might try visiting some weekend garage sales, not that I've ever been to
even one of them myself, but that might be your best bet.

Trust me I always check them out if I see them driving around, people just have more junk these days, quality electronics are few and spare in my area

Yeah it was my birthday... I can't operate anywhere except vhf and uhf portable because I live in an apartmentand quite frankly the local repeaters drive me buggy... or they did the last time I was on the air... I have a bunch of 144, 220 and 440 MHz portables and I am too lazy to re-cap them. Real old school stuff Icom IC02?, IC03?,s and a Yaesu or two. Big OLD thumbwheel programmed transceivers... I bought a couple of AD9850 DDS boards... was going to rip out the synthesizers and replace them with NCO's... Still on my project list though as soon as I can figure out how to modify the Icoms... they used a varactor tuning system for the receiver RF and mixer and would be rather numb at best without that tuning. I have often wondered why there wasn't an Amateur Radio group here... Too

Bob

I have often wondered why there wasn't an Amateur Radio group here... Too

There are a few of us around. However beyond a morse code encoder/decoder project or two, not many ham projects get posted around here.

Lefty: WA6TKD