> > Seems like you could do a rocket motor ignitor with them pretty nicely.= =A0:) The > > reverse voltage thing is obvious, but they also fail spectacularly with= high inrush > > currents. Best Tantalum failure I've seen was in a working PCB. It shrieked then warbled, then smoked, then burst into flame with a nice flame jet, all the while still supplying sound effects (as I recall) and then literally exploded with a very impressive bang for an indoor event. Regrettably, attempts to persuade other Tantalums to imitate that one only ever met with partial success. I have a part reel of older ones which are large by todays standards which refuse to do anything really spectacular when abused. Maybe they are really solid Al? > I have thought of filling a 3 litre plastic drink bottle with compressed = air, dry ice > up to about its maximum pressure capability, NB Caveat Emptor / IANAL / Do not try this at home / All care no responsibility / Be sensible !!! I have substantial experience using PET softdrink bottles for high performance water rockets. HP here means they may pull 100g off the launcher and if you want to see them ascend you MUST look up before they launch. Photograph the launch and you find that the exiting water falls upwards from about 2 metres above the ground until Brennschluss. An optimally filled bottle is about 1/3 water and 2/3 air. CofG moves backwards during most of expulsion and then forwards again towards the end (makes sense when you work through it) with maximum instability occurring late in thrust phase when CofG is at rearmost point. Thrust tends to last 10's of milliseconds depending on pressure, fill%, orifice etc. At 100g that's enough for the bottle to "almost vanish" at Apogee when viewed from ground level. Toys they are - but serious ones. Energy stored approaches that of a 38 Magnum shell. Less destructive on impact, fortunately. Smaller capacity bottles take substantially higher pressures. It's both due to hoop stress being proportional to diameter and because to some extent the blank they blow them from does not seem to increase in mass at the same rate as bottle capacity so you get a thicker wall per capacity. A 1.5l Pepsi bottle will hold 100 psi for months, will tolerate about 130 psi without too much distress, and starts to grow larger while watched at 150 psi. A bottle that is overpressured will produce magic smoke equivalent in a stunningly impressive manner. This is to be avoided if you are trying to launch a water rocket. A small nick in a bottle with a sharp implement will not result in a small hole and a gradual pressure release. Transition from small nick to no bottle is closer to instantaneous than the ear numbed brain can quantify. Self deconstructing bottles will generally throw plastic only small distances - probably usually under two metres and often under one. But occasionally a bottle neck or similar may be thrown substantially further. Safety glasses are a good idea. Other protective clothing optional but you are unlikely to sustain major injuries from fragments if eyes are protected. YMMV. Ears can take some minutes to regain useful function. A well streamlined 1.5l bottle with nose cone and fins and no aerobraking will impact at 75 kph+. Being in its way would be unwise. > and taping a tantalum cap to the outside, setting it up somewhere, and ap= plying reverse voltage to the cap, when the neighbours are having a particu= larly noisy party ... Anything that mechanically compromised sealing of bottle at 100 psi + would rapidly result in while bottle shredding. Rockets do not fly well in that mode. My adult children both left home about 5? years ago. When I occasionally meet their friends they still enthuse about the Guy Fawkes nights we used to hold :-) __________ > > I don't design them into anything anymore. > How about the Niobium version that AVX and others are manufacturing as eq= uivalents? After all ceramic caps are as bad as tantalums as catching fire.= I have my own experience of that when doing a burn in on arrival of a new = computer ... Hyperjump ... Solid Al have for decades done what Tantalum usefully do, but without the pyrotechnics. R --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .