Many years ago at [company name withheld] we had a batch of several hundred faulty electolytics which had to be disposed of. We had great fun making a mortar - a piece of copper tube with a wooden plug with a nail through it - and having a target shooting contest. I also remember having a batch of memory board assembled with all the tantalum capacitors put in the wrong way round. They lasted several weeks until one night I was awoken by andanguished night shift operator reporting that small puffs of smoke were being regularly ejected from the machine and should he shut it down. __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb *Sent from my etch-a-sketch* On 26 February 2018 at 12:40, wrote: > High school. Rat's nest of free space wiring. Neon bulbs, capacitors > (relaxation ring oscillator). Powered by half bridge directly from AC lin= e > (no transformer). Main supply cap probably 50uF @ 200V or so. Short > circuit. > Small rocket dragging 115VAC / 160VDC all around the workbench. Much > excitement. > > - - Bob Ammerman > RAm Systems > > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of > DrSkip > Sent: Monday, February 26, 2018 12:09 AM > To: piclist@mit.edu > Subject: Re: [EE] "X" marks the spot > > I suspect the X is initially weaker than the glue holding the can on, so > rapid pressure increase will break open there. Perhaps over the 30 minute= s > heat weakened the glue to the point of it being the weak point for a > gradual > pressure buildup. > > Dr Skip > > > On 02/25/2018 08:36 PM, Bob Blick wrote: > > By mistake I put an electrolytic capacitor in backwards. A very generic > 100uF, 50V cap exposed to 16V with the equivalent of about 700 ohms in > series with it. It lasted about 30 minutes, then went off with a bang. Yo= u > can maybe see the damaged heatshrink where the can hit an immovable objec= t. > > > > Please note the scored cross on the top of the can. Isn't that > > supposed to split and protect me from its rapid self-disassembly? Yes, > > I was right there, close at hand, trying to figure out why all the > > voltages were wrong. Perhaps their die for the venting "X" was worn > > out after 20 million caps. I guess that's what I get when I pay USD > > 0.03 for caps off of Aliexpress instead of USD 0.11 at Digi-Key :) > > > > I guess I learned a lesson in false economy today. I didn't lose an eye= , > but I'm going to change my buying habits a little. Obviously I made a > mistake putting the cap in wrong, but if I'd used a quality cap perhaps I= 'd > have only been startled with a scary hiss instead of a projectile. Take > heed! How many lives do you really have? > > > > Cheerful regards, > > > > Bob > > > > > > > > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change > your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .