Where to buy components to explode some capacitors - Page 1
Forum section: electronics / beginners

author: skillz21
author_rank: Frequent Contributor
timestamp: August 21, 2017, 06:26:15 am
content: Hi,so I have this Science project and I want to do "what reverse voltages are needed to make different capacitor values explode". Now, does anyone know a store in Australia (eBay stores, or other online stores) that have electronics components for sale... I need them within 2-3 weeks maximum... (same week delivery would be great but I might be hoping for too much here).Price is also a concern here, this is so urgent that I even resorted to looking at the Jaycar website... their stuff is so expensive (for those who don't know, a single push-button will set you back $1.30... I know from experience, I used to buy stuff there when I was smaller, I'm a bit smarter now). Anyway, I am looking for a boost converter, whether I can buy one or buy parts to build one doesn't matter (prebuilt one would be easier though). Ebay is preferred...Thanks so much for any help.

author: bjcuizon
author_rank: Frequent Contributor
timestamp: August 21, 2017, 08:14:26 am
content: Are you considering Aliexpress? There is this store called"Professional semiconductor suppliers"Here's some of their caps if you need them:https://mcigicm.aliexpress.com/store/group/electrolytic-capacitor/506373_500752407.html?spm=2114.12010608.0.0.2995e5c0pGQjNLjust choose your flavour!They also sell some modules..didn't research much though....And they usually ship 17-36 days to NZ(maybe its different to Australia)-if that's OK for you.DISCLAIMER: I am not affiliated with this store in any way.

author: BradC
author_rank: Super Contributor
timestamp: August 21, 2017, 08:51:20 am
content: Futurlec is good too for lots of really cheap passives. If you need it super-urgent you can e-mail them and ask for an expedited shipping quote. You're pushing a deadline for cheap generic stuff. If you want it now you need over-the-counter or pay for good service.Maybe list what you actually need. I'm sure there are loads of people (cough) like me who have piles of "just in case" parts. You never know, you might jag an envelope full of bits if someone has what you are after. I picked up a shoe-box full of passives for cheap from a bloke on here. He no longer needed them, and I had a use.

author: skillz21
author_rank: Frequent Contributor
timestamp: August 21, 2017, 09:41:12 am
content: Ok, for the components: boost converter module..... to be honest, if I actually tried, I could probably find all the components I need from the circuit boards that I have lying around... the problem is, I am not the greatest at desoldering, for some reason, solder wick never seems to work for me. You guys have any quick tips on desoldering.By the way (no hate please) I don't have a proper soldering station, I have a plug in soldering iron. Now before everyone flips out on me, I know, I really need to get a soldering station, but they seem pretty expensive and my budget when it comes to electronics is not that great (I'm only 13). It's on the list of things I need to buy, along with an oscilloscope.So does anyone have any tips on desoldering? my technique is to hold the component with a pair of pliers and yank when the pad is melted. not the best really, about a quarter of the things I desolder have their legs pulled out.... any tips?Thanks,

author: SeanB
author_rank: Super Contributor
timestamp: August 21, 2017, 05:58:50 pm
content: Want to pop electrolytics is simple, 12V from a SLA alarm battery applied in reverse, wait 20 seconds and boom. Even works on wet tantalums, though those generally are boom clunk as either the slug or the case ( whatever was lighter or less securely held) lands somewhere in the vicinity. Standard dry tantalums there just is a puff of smoke and a white hot burst of fire instead. Apply power through a 20A home circuit breaker, acts as power switch and will disconnect after the boom, or at least can break the short circuit current a few times as test.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 21, 2017, 06:25:26 pm
content: Quote from: skillz21 on August 21, 2017, 09:41:12 amFirst - don't be ashamed of your equipment. You will replace it as need and ability arises. I was thirty years into this hobby before I got my first good soldering iron, and only recently got an actual soldering station - fifty + years into the hobby. Good technique can overcome many equipment limitations. Good technique comes from practice and thought about what went wrong during practice.Solder wick works great when everything is right - not so much other times. Preferably the wick is fresh, bright and came well fluxed. When working on a budget these may not be true, but the solution is flux. I use a rosin based flux and add a generous coat to my old solder wick. Makes it work almost like new. Solder wick also requires more heat than making a joint, you need to heat the joint and the wick. While most inexpensive soldering irons are overpowered, yours may not be. To protect delicate components when desoldering with wick heat the wick separately before applying to the joint. Another point which is painful when you are on a tight budget or when on hand supplies are low is that you can't be stingy with the wick. While solder wick can hold a lot of solder, its ability to draw solder out of a joint drops rapidly as the wick fills. Clip it off and move to the next segment before it becomes saturated.Another technique that is relatively inexpensive for desoldering is the Soldapult and its relatives. Many people swear by them.A hammer and tongs approach also works. Heating the joint until the solder melts and then striking the board against a hard surface. The heavy solder is driven out of the joint. This technique has many drawbacks, including a requirement for more hands than most people have, the dangerous spray of hot solder that results (it can come back also as the board rebounds), the risk of a solder splash migrating to someplace where it shorts your circuitry and the danger of component damage, but it has been used by many people successfully. The primary advantage is that it uses no special equipment or consumable supplies. With thought and care the drawbacks can be mitigated, but not eliminated.

author: skillz21
author_rank: Frequent Contributor
timestamp: August 21, 2017, 10:09:14 pm
content: Thanks, CatalinaWOWSo, for the heat the joint then hit it technique, do I just use a soldering iron, and then immediately strike it against the ground? and for the wick, do I get like a flux pen and then apply it to the wick?

author: skillz21
author_rank: Frequent Contributor
timestamp: August 21, 2017, 10:19:49 pm
content: Quote from: SeanB on August 21, 2017, 05:58:50 pmWhat I want to do, is use different (electrolytic, to be honest I didn't even think of others, but electrolytic seems easier, they are pretty plentiful on circuit boards) capacitor values and put a steadily climbing reverse voltage on them, I'm going to try and take down the voltage at which each capacitor explodes. also, does the voltage that the capacitor is rated for effect the reverse voltage needed for it to pop?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 21, 2017, 10:41:49 pm
content: Quote from: skillz21 on August 21, 2017, 10:09:14 pmYou will have to experiment with what works best for your situation. With large PWBs grab one edge in a vise. Pull the board as far as it comfortably will go and then heat the joint. When the solder liquifies, let go. The board will spring away, and often leave the solder hanging in the air. Or flying out the other side when the board springs back.You can strike boards against the ground, but in many cases the dirt/grass/whatever is soft enough that solder is not shocked out of the joint. A board, or rock or bench or other hard surface works better.A soldering iron is the safest thing to use for heating the joint. If you have access to a propane torch you can also use that, but with far greater risk of damage to components and of starting a fire. The torch can be faster, but I don't recommend it until you have a lot of experience and have parts you really don't mind losing to the process.Think through the physics of what is happening. You are trying to cause a large acceleration that will cause the solder to overcome capillary forces and leave the joint. The shock you will need is strong. Many g's, preferably just less than the damage threshold for the components involved. You can think up methods that are appropriate to the equipment you have, your skills and coordination and the parts you are trying to salvage. This technique isn't what you would want when repairing high value equipment. There is risk of damaging things.I re-emphasise, if you are going to do this, protect your eyes and for best protection wear long sleeve shirts and long pants and shoes and gloves. There will be solder splatter. You may be tough enough to ignore minor burns on your arms and legs, but losing your vision is something you really don't want to do.I have not used liquid flux in a pen on solder wick, but it should work. The downside is that it won't be long lasting. Resinous flux will stay good (and messy) for years. In my experience it is also cheaper. A downside is that it is more difficult to clean, but in this application cleaning is not a problem.

author: bjcuizon
author_rank: Frequent Contributor
timestamp: August 22, 2017, 04:48:39 am
content: Quote from: skillz21 on August 21, 2017, 09:41:12 amHaving a decent but expensive iron may be useful if you're really advanced and really serious or a professional. Now I'm just using a plug-in iron too from jaycar. hehe. I liked having the idea of buying a name-brand, high-quality, variable temperature iron but I figured I don't need that sort of stuff for now as I'm still a hobbyist.Anyway, to desolder some components off a board, heat up its pad one by one and gently rock the component as you heat the pad. (this works for two-leaded components only). I also sometimes use a solder sucker instead of the wickHave fun with electronics!...And good luck with your project.

author: BradC
author_rank: Super Contributor
timestamp: August 22, 2017, 05:03:49 am
content: I started out with a Superscope and graduated to a Mini-Scope when I started doing SMD. When my parents figured I was serious about this electronics gig they bought me a Hakko 926 station. That was over 25 years ago and I still use that iron from time to time.You can do great work with a standard plug-in iron. A station is a nice upgrade if you are doing long sessions as it keeps tip temperature under control. When I've used a plug-in iron I've put it into an old black & decker power board with a switch. When the tip is starting to look a bit too hot, just switch it off until it needs switching on again.You don't need $$$ tools to have a go but they can make life easier as you get more serious. Btw I didn't get my first CRO until I was 35. It's amazing what you can do with blinking LED's, an audio signal tracer and other lash-up diagnostic equipment.

author: jonovid
author_rank: Super Contributor
timestamp: August 22, 2017, 05:16:37 am
content: Quote from: skillz21 on August 21, 2017, 06:26:15 amhave FUN

author: FrankBuss
author_rank: Unknown
timestamp: August 22, 2017, 06:18:53 am
content: For a scientific experiment, it might be useful to use a regulated power supply. If you buy it from China, might need longer than 2-3 weeks, but something like this looks good:http://cgi.ebay.com.au/271602474268There are cheaper version with 30V and 3 A, but with 60V you can pop more capacitorsIf you plan to do more with electronics, such a power supply with adjustable current limit is essential and will last forever.For capacitors take a look at Farnell:http://au.element14.comIn Germany they provide next day shipment. But here you need to be a company to buy from it. Athttp://digikey.comeveryone can buy components, and they ship in 2-3 days worldwide. Using one of these two shops has the additional advantage that you can get capacitors from known vendors, which are not counterfeit and you know the exact type and rating, so that if you publish your experiments, everyone can reproduce them. If you buy some unbranded parts from eBay which someone sells from their junk bin, you can't be sure what you get and your findings are not reproducible.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: August 22, 2017, 09:54:49 am
content: Just be aware that some very old capacitors don't so much go pop as boom. Seen one split a PCB in two. If your face is in the way of the contents, could ruin your whole day.

author: skillz21
author_rank: Frequent Contributor
timestamp: August 22, 2017, 10:42:32 am
content: Quote from: IanMacdonald on August 22, 2017, 09:54:49 amYeah, I'll be careful... I popped a cap today with two 9v batteries... I wore safety goggles (that's a first for me......). Anyway, yes I will be wearing safety goggles, hopefully, that will be adequate.

author: Ian.M
author_rank: Super Contributor
timestamp: August 22, 2017, 10:52:45 am
content: No, not adequate. I'd strongly recommend experimenting outside with a concrete paving slab between you and the cap and an impact resistant mirror (plastic or polished stainless steel) to view it with.

author: skillz21
author_rank: Frequent Contributor
timestamp: August 22, 2017, 11:27:23 am
content: I'm doing it outside anyway, so should I just explode it outside with me inside?

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: August 22, 2017, 01:19:59 pm
content: Careful what you wish for- The pic shows a capacitor that suffered an energetic disassembly in a bench belt sander. My friend, who was using it at the time, said he thought that he had been shot. I trust his description as I know that he has been.Bear in mind that there used to be some nasty chemicals in some capacitors, so old stock is probably not advisable.Regards, BT

author: BradC
author_rank: Super Contributor
timestamp: August 22, 2017, 01:48:47 pm
content: Quote from: BurningTantalum on August 22, 2017, 01:19:59 pmAnd that kiddies is why we don't put out capacitors into a belt sander!

author: Ian.M
author_rank: Super Contributor
timestamp: August 22, 2017, 02:16:51 pm
content: For comparison, aBLEVEexplosion of 2 grammes of water can have comparable energy (depending on the peak temperature) to the propellent in a .22LR rifle cartridge, so with larger caps, if the bung is expelled or the case parts at the base, the casing can rocket off at high velocity with a significant amount of energy. Limiting its trajectory and what it can impact is essential.Destructive testing of capacitors outside is only OK if the fragments cant hit any people, animals, or fragile objects, and the residue can be cleaned up without contaminating ponds or streams, vegetable patches or play areas used by children.N.B. if you want a transparent blast shield to let you observe it directly, you'll need a thick sheet of polycarbonate. Don't use Acrylic - it tends to fracture in high speed impacts and may not slow the fragments down enough for safety.@BradC: I suspect the capacitor was inside the belt sander, probably the motor staring cap, and it was probably a 'fresh underwear required' event.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: August 22, 2017, 02:52:52 pm
content: Electrolysis of water generates Brown's Gas which can go with quite a bang if it's compressed and ignited. I wonder if some of the more dramatic cap blows are mainly due to this rather than just gas pressure. Quite possibly a spark as the can bursts could ignite it.

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 22, 2017, 03:46:55 pm
content: If you decide to destroy Tantalum capacitors, they don't really explode, but rather burn-up rather vigorously.Keep it away from flammable materials.

author: skillz21
author_rank: Frequent Contributor
timestamp: August 22, 2017, 09:44:15 pm
content: What capacitors would you guys classify as 'old'?

author: Cliff Matthews
author_rank: Unknown
timestamp: August 23, 2017, 12:47:28 am
content: 30 years ago, my brother and I wheeled-and-dealed 20kg of bagged caps from a place called Active Component Sales (Freddy) in Toronto. From our 9th floor corner apartment, while sorting out our loot, we blew up a bunch of junk caps by dropping them out a window from a 10-meter wire connected to a 90volt transfo at night. Up went the wire in silence after each bang.. Can't fight it? At least dangle the wire to the side of the window so your neighbors below can't see it..

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: August 23, 2017, 02:52:08 am
content: Brad C-Sorry, I didn't make the anecdote very clear (plus it was a bench grinder...)The cap was a motor run cap inside the cast iron base.The odd thing is that the grinder had run for many years without a problem. The cap was original; the unit made in Taiwan, when Taiwan made some half decent electric tools. The cap is clearly marked as '120V working voltage' !!BT

author: BradC
author_rank: Super Contributor
timestamp: August 23, 2017, 04:29:15 am
content: Quote from: BurningTantalum on August 23, 2017, 02:52:08 amNo it was perfectly clear. It appears my sense of humour is not easily understood.

author: Ian.M
author_rank: Super Contributor
timestamp: August 23, 2017, 04:38:36 am
content: 'Dry' humour as plain text in a technical forum is often misunderstood (or deliberately misinterpreted by pedants). Tag it with an appropriate smiley and even the pedants realise its just for the LOLs.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: August 23, 2017, 02:29:19 pm
content: Sorry Brad, I blame it on my Pom sense of humour, or lack of it !I was rather amazed and disturbed as to why the OP didn't want to investigate the charge/discharge curves of caps, or something educational- although I seem to recall a young BT hanging electrolytics, connected to a diode and the shop Variac, out of the workshop window.BT in WA