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My cat water fountain comes with a spicy USB power adapter

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Re: My cat water fountain comes with a spicy USB power adapter

#41

Post by etimberg »

nicolaslem wrote: post #26
can16358p wrote: post #9

Earlier quoted context omitted.

I think when it comes to safety restrictions should be there. The hacker in me hates it too but just imagine if a small portion of standard-looking outlets did not output 220V (or whatever standard you have) and say 330V. Many applicances would break, or perhaps even catch fire. If there were many different USB-A devices and people were used to checking the voltage output before plugging, that might not be needed, bu…

From my experience appliances tolerate a wide range of voltages. The outlets in my house routinely deviate from the standard 230V, with the lowest I have seen at 170V and highest at about 260V. I have not had any appliance malfunction. Edit: I am not advising anyone to deliberately do stupid things, simply mentioning that from my experience the builtin margin is fairly large.

Are you measuring RMS voltage or just the instantaneous voltage?

An RMS voltage of 230V corresponds with a peak voltage of ~325V so reading of 260V could theoretically happen.

Re: My cat water fountain comes with a spicy USB power adapter

#42

Post by KaiserPro »

lxgr wrote: post #15
bArray wrote: post #6

To be completely fair, those power banks should have a diode (or some protection circuitry) to prevent their damage. A loose cable could easily put higher voltage on the port than 5.25V. That said, what an awful USB port to come across. A little reading wouldn't have gone amiss though. My natural reaction would have been to assume it was an output, not an input.

A diode doesn’t protect from over-voltage; that requires more complicated circuitry as far as I understand. And how would a loose cable cause a voltage spike?

perhaps a they meant a zener diode, which can be used to clamp a voltage? The downside being that it dissipates the excess energy across it's self.

> how would a loose cable cause a voltage spike?

From the top of my flu-y head, connecting and disconnecting an inductive load (like a motor) can cause spikes. However in USB land, that's pretty rare.

dc-dc step up devices use an oscillator to charge and discharge an inductor to achieve a certain voltage increase. They _could_ be noisy when starting up, or have transient load.

Re: My cat water fountain comes with a spicy USB power adapter

#44

Post by red_trumpet »

anonu wrote: post #38
lxgr wrote: post #28

This actually makes me quite happy that most stuff does not come with a wall adapter anymore these days, but only with a USB plug. There are much worse things than 7V that a bad adapter can output. One of the scariest failure modes I’ve recently learned about is a supply that still provides 5V between both pins – but 225V and 230V to ground, respectively…

> respectively not sure I follow you. can you clarify what you mean by both 225v and 230v to ground? You are measuring the potential between ground and USB output?

There are two pins. One has 225V to ground, the other one has 230V to ground. So the voltage from pin to pin is still 230V-225V = 5V.

Re: My cat water fountain comes with a spicy USB power adapter

#45

Post by cjrp »

currency wrote: post #31
wiredfool wrote: post #17

Earlier quoted context omitted.

It's got a CE mark, but it's unclear if it's valid or not. This is a mandatory certification in the EU, like the UL listing in the US. The device is specifying the output voltage, which isn't in spec for the connector, but it is (apparently) accurate.

There's a deceptively similar mark that stands for China Export and does not indicate EU certification[0]. [0] https://www.kimuagroup.com/news/differences-between-ce-and-c...

Wow, that's incredibly close. I assumed there would be a public database of CE (European) approved devices or manufacturers, but I can't find one from a quick search.

Re: My cat water fountain comes with a spicy USB power adapter

#46

Post by jdboyd »

wiredfool wrote: post #17
denotational wrote: post #2

This is the sort of thing that almost (but not quite) pushes me to support mandatory certification (enforced by patents/other IP protections) for consumer devices that use a familiar connector like USB. Consumers shouldn’t need to worry about the specific output voltage; the presence of a USB-A connector should indicate that it abides by the specification. The hacker in me hates the idea of enforcing something like t…

It's got a CE mark, but it's unclear if it's valid or not. This is a mandatory certification in the EU, like the UL listing in the US. The device is specifying the output voltage, which isn't in spec for the connector, but it is (apparently) accurate.

UL isn't actually mandatory in the US. The only thing mandatory that I am aware of is FCC certification for devices with signals over a certain number of Hz, and they wouldn't care about a USB port being abused.

Re: My cat water fountain comes with a spicy USB power adapter

#47

Post by throwawaaarrgh »

loufe wrote: post #13

My recent work experience leads me to believe CE approval is a rubber stamp. I don't have any clue what that certification is worth to anyone.

Self-attestation is introduced when the industry complains that having a 3rd party verify is too onerous and could hurt business. And they're not wrong, but the result is companies rubber stamp their own compliance. You see it a lot in DoD compliance now, for example.

Re: My cat water fountain comes with a spicy USB power adapter

#48

Post by nicolaslem »

etimberg wrote: post #41
nicolaslem wrote: post #26

Earlier quoted context omitted.

From my experience appliances tolerate a wide range of voltages. The outlets in my house routinely deviate from the standard 230V, with the lowest I have seen at 170V and highest at about 260V. I have not had any appliance malfunction. Edit: I am not advising anyone to deliberately do stupid things, simply mentioning that from my experience the builtin margin is fairly large.

Are you measuring RMS voltage or just the instantaneous voltage? An RMS voltage of 230V corresponds with a peak voltage of ~325V so reading of 260V could theoretically happen.

That's the reading from my UPS, I believe it's RMS since it reads 234 V currently.

Re: My cat water fountain comes with a spicy USB power adapter

#49

Post by piaste »

currency wrote: post #31
wiredfool wrote: post #17

Earlier quoted context omitted.

It's got a CE mark, but it's unclear if it's valid or not. This is a mandatory certification in the EU, like the UL listing in the US. The device is specifying the output voltage, which isn't in spec for the connector, but it is (apparently) accurate.

There's a deceptively similar mark that stands for China Export and does not indicate EU certification[0]. [0] https://www.kimuagroup.com/news/differences-between-ce-and-c...

For context, this isn't an official mark created by China or any other entity.

It's just some fraudulent manufactures that are using a paper-thin excuse to illegally apply a fake CE mark.

Re: My cat water fountain comes with a spicy USB power adapter

#50

Post by cesarb »

can16358p wrote: post #9
denotational wrote: post #2

This is the sort of thing that almost (but not quite) pushes me to support mandatory certification (enforced by patents/other IP protections) for consumer devices that use a familiar connector like USB. Consumers shouldn’t need to worry about the specific output voltage; the presence of a USB-A connector should indicate that it abides by the specification. The hacker in me hates the idea of enforcing something like t…

I think when it comes to safety restrictions should be there. The hacker in me hates it too but just imagine if a small portion of standard-looking outlets did not output 220V (or whatever standard you have) and say 330V. Many applicances would break, or perhaps even catch fire. If there were many different USB-A devices and people were used to checking the voltage output before plugging, that might not be needed, bu…

> just imagine if a small portion of standard-looking outlets did not output 220V (or whatever standard you have) and say 330V.

We have something like that here in Brazil. On cities which use 127V as the standard voltage (some cities use 220V), you can get 220V by using a pair of phases instead of a phase and the neutral, and it's common to find a few standard-looking sockets which are 220V instead of 127V. They might be colored red, they might have a yellow sticker saying "220V" next to it, or they might be completely unmarked. If your device is 127V only, or it has a manual 127V/220V switch which is on the 127V position, and you plug it into one of these 220V sockets, it will be damaged.

(The standard we use for consumer AC power plugs and sockets, NBR 14136, does not make a distinction between voltages; the same plugs and sockets are used for both 127V and 220V.)

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