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I just read this article: iPad charger teardown: inside Apple's charger and a risky phony

Basically I would like to see by myself the effects of a bad power supply failing.

Can it be done safely?

Edit: Here are the reasons why I want to see it happen.

I would never buy a shitty power supply like this one (~3€ on eBay) for a device which costs around 500€, but considering the really low price, I am willing to spend some time to see what would have happened if I had bought and used this one. As mentioned in the article, one person seems to have died because of a badly insulated charger. So basically, I want to replicate the typical use case of such a power supply, and safely see how it fails. Will it explode, will it slowly die, or just stop working? I certainly am not going to plug my iPad in it. I am ready to spend a small amount of money on disposable electronic components if necessary. I hope this clarifies why I want to have it fail. And of course, my main concerns in this experiment are my own safety, and not to damage anything else beside the charger and the circuit that will draw current from it.

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closed as off-topic by Leon Heller, Daniel Grillo, Andy aka, placeholder, Joe Hass May 15 '14 at 21:32

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Leon Heller, Daniel Grillo, Andy aka, placeholder, Joe Hass
If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ My english is not good enough to understand clearly what you mean. You want to know how to cause big failure with fire and not get hurt, or whats the "electrical" difference between good and bad charger? \$\endgroup\$ – Kamil May 15 '14 at 20:02
  • \$\begingroup\$ OP is asking how to cause a failure. In other words, he/she wants to test the safety standards. Why X mm creepage, for example. In the article, it is mentioned "use the charger in a humid environment, poof". I believe OP wants to basically replicate UL tests, not how to improve a bad power supply. \$\endgroup\$ – dext0rb May 15 '14 at 21:12
  • \$\begingroup\$ @dext0rb Exactly. Feel free to rephrase my question if you think you can improve it. \$\endgroup\$ – user41899 May 15 '14 at 21:21
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    \$\begingroup\$ It seems the moderators would prefer a question like "I am designing an AC adapter, how can I test it to failure? What are the methods and safety considerations?" \$\endgroup\$ – Matt B. May 15 '14 at 21:50
  • \$\begingroup\$ Voting to reopen, since it is not on use of an electronic gadget, but on testing its failure modes, which is a topic related to EE design. (+1) to try to do it safely. \$\endgroup\$ – Lorenzo Donati Jul 8 '15 at 13:30
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Are you trying to make it burn/explode on purpose? Some things to be careful about would be fire, smoke, electrical short to high current, live wall voltage.

Fire

Put it on a large concrete slab or something non-flammable. Maybe build a platform out of concrete paver stones. The adapter may burn but it won't catch other things on fire, e.g. your lab bench.

Explosion

Put it inside a Plexiglass box, possibly with holes to vent gas pressure, or metal mesh cage, sturdy enough to retain small pieces without exploding itself from the internal pressure.

Smoke

Put it under a vent hood, or vent the room well with a fan (preferably with smoke filter), or do it outside, because the smoke from burning components and plastic case will be unhealthy to breathe.

Electrical Short

A dead short on AC mains power can draw enough current to melt copper wiring and send droplets of molten metal flying in all directions. You do not want to be staring into this without safety goggles on when it happens. Stay far away and use a video camera to record what happens instead. Be sure you can kill power to the adapter without having to touch it once you see problems occurring, for example by unplugging a long extension cable from the other end. Also be sure your circuit breaker or fuse box is working, so you don't set your building on fire overloading the wiring in the walls.

Don't touch the damaged adapter until after disconnecting it from power and allowing it plenty of time to cool down and vent smoke and fumes.

Just because an AC adapter is poorly designed doesn't mean it will catch on fire as soon as you plug it in. What are you planning to do to trigger a failure?

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  • \$\begingroup\$ Would it be a good idea to use a power strip with a built-in fuse so that I can contain the failure ? Also, what circuit can I use to draw around n Watts of power from this cheap charger ? \$\endgroup\$ – user41899 May 15 '14 at 21:16
  • \$\begingroup\$ You don't need a "circuit" for a load, a power resistor will work fine. Calculate ohms by the current you want, R=V/I. Choose a power rating well above the planned usage and it shouldn't burn out (although it will get hot). \$\endgroup\$ – Matt B. May 15 '14 at 21:48
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Depends on how bad the supply is and what your definition of "bad" is.

It's trivial to add undervoltage or overvoltage lockout to a power supply you're designing. It's more challenging to do that to a cheap adapter you've picked up off eBay or some random source.

You could always add undervoltage and overvoltage lockout to a USB "interposer" cable between the supply and your iPad. A handful of FETs and a zener diode would get you 95% of the way. You could also add some additional decoupling capacitors and filtering to help smooth things out and clean up the supply even when it's not failing.

The problem with doing that, though, is that when you're done you've got a bigger, uglier and more error-prone solution in hand than if you just bought a good supply in the first place.

edit to address comment: You don't mention what kind of failure mode you are after, but if you just want it to burn out it is probably enough to load it down so that it is just on the cusp of failing, and wait. Say it's a 10W adapter; R=V/I and P=V^2*R so 5V/2A is 2.5 ohms and 5V*5V/2.5 ohms is 10 Watts. Find or build yourself a 3 ohm, 15-20W resistor, connect it across +V and GND and wait. You'll likely cook the thing in no time, assuming it can even supply 5V / 3 ohms or 1.7A to begin with, which is unlikely.

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  • \$\begingroup\$ About your last paragraph: I don't want to make it work safely. I want to have it fail. \$\endgroup\$ – user41899 May 15 '14 at 21:17

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