What kind of power adapter does my router need?
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I have TP-Link TL-WR841N. My brother "borrowed" the power adapter for his guitar thingy and lost it somewhere between here and Germany. Where can I find the specification (output current and voltage) for it so I can get replacement? It's not on the router, it's not in the manual, and people(?) making unboxing videos don't care about the adapter enough to make a single clear shot of the label. Where can I find this info?
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@gąska Google Images has this image which looks it's got a "Power" section on the label:
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@hungrier huh. Apparently they print different labels in Poland. Mine doesn't have this info. Many thanks!
Though this particular image is too low-res to read anything.
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@gąska said in What kind of power adapter does my router need?:
Though this particular image is too low-res to read anything.
I can barely read the 9V rating on it if I zoom way in.
BTW, almost all digital devices that have external power adapters also regulate the power internally. In all likelihood that is more of a minimum power you would need to power the device. 9V plus a tolerance is enough to keep it above the dropout voltage for the onboard regulators. Onboard of it would be either a linear regulator or some manner of switching power regulator (It is usually linear). If it has a standard 2.1 mm DC power input jack you would most likely be fine with a standard 12V power input, which is more readily available.
If it has a linear regulator onboard it may burn off a few more milliwatts of waste heat. If it has a switching regulator onboard it is unlikely that a 3V jump would change anything at all.
All of this goes out the window on analog devices.
YMMV though. IANAEE
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@polygeekery
In my experiences with wireless radios, unless you can find documentation claiming support for a higher voltage than printed on the tin, I would not recommend “if it fits it sits” for AC adapters.We had a device that required 5V 2A input, but had the standard 2.1mm plug like the 12V adapters that were more common (and that was used by a different device we installed in other cases). We had a lot of those 5V units that were suddenly missing their magic smoke when the surveyor connected them to the 12V 1A adapter by mistake. Whereas the 12V 1A radio just didn’t get very good reception if you booted them with the 5V 2A power supply.
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@polygeekery So what you're saying is skip the adapter and plug it straight into 120 VAC.
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@mott555 Considering what he does in his spare time...
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@izzion said in What kind of power adapter does my router need?:
I would not recommend “if it fits it sits” for AC adapters.
Yeah, this. There is really no correlation between size, voltage/amp rating, or even which terminal is positive and which is negative.
Under-voltage usually won't hurt anything, but the device probably won't work. Overvoltage is usually pretty bad, like letting the magic smoke out bad. (Also voltage polarity being backward can do this if the device isn't diode protected... if it is, it just won't work.)
A higher amp rating is fine just so long as the device is working properly; it just means that the device could draw more amps if it needed them (without overheating the power supply and/or pulling the voltage down as much). If the amp rating is low, though, you risk the power supply overheating or failing, or failing to provide a high enough voltage and causing the device to malfunction.
So about the only one that gives you real leeway is giving the device more amps than it needs. If your device calls for a 150mA power supply and all you have is a 200mA power supply, but the voltage, connector, +/- terminal arrangement is all the same, you're fine. If the device is working properly it'll still only use 150mA even if the power supply is capable of supplying 200mA.
edit: well, and if the +/- terminals are backward, you could cut the cord and splice it back together backward to reverse the tip polarity. But that's a bit more hacking than some people are comfortable doing.
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@Gąska
Additionally, the spec sheet for the router is: https://static.tp-link.com/res/down/doc/TL-WR841N_V10_Datasheet.pdfWhich specifies 9V / 0.6A for the external power supply. Doesn't specify center pin positive or negative, and I don't see that when blowing up the label in the picture @hungrier posted. Usually there's a symbol on the casing of the router, near where you plug the adapter in, that should look something like one of these two:
Where the dot indicates the center pin's polarity and the C outside the dot indicates the outside of the plug's polarity.
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@anotherusername said in What kind of power adapter does my router need?:
pulling the voltage down as much
While you overall comment is spot on, there are (almost always low quality) devices that deliberately use an underpowered (lower amperage capability) and count on the [over-rated] current draw to partially collapse the voltage. These devices (because they are crap) typically have zero protection circuitry. So if you do use correct voltage (as spec'ed) you can actually fry the device.
When this happens, I usually say good riddance!
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I should have mentioned that my father is an actual electrical engineer so I know all this stuff. I should have also mentioned that there's a well stocked electronics flea market in my city so availability isn't a problem. Still, I guess it's useful knowledge for other visitors.
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@izzion said in What kind of power adapter does my router need?:
In my experiences with wireless radios, unless you can find documentation claiming support for a higher voltage than printed on the tin, I would not recommend “if it fits it sits” for AC adapters.
Analog devices?
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@polygeekery
I mean, they were digital in the sense that they were basically specialized wireless routers, with a standard Ethernet port, a WiFi radio, and software to bridge the two together and control the radio.And a serial port with a specialized connector that was super easy to damage, so you were constantly having to buy new programming cables from the manufacturer because the cable got snagged under the surveyor's van seat rails and is now ded.
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@izzion said in What kind of power adapter does my router need?:
I mean, they were digital in the sense that they were basically specialized wireless routers, with a standard Ethernet port, a WiFi radio, and software to bridge the two together and control the radio.
Well, I never meant my recommendation to be for sensitive and expensive equipment like that. But in general I have found inexpensive (until you get to the super low end where they do fuckery to make things super cheap) to be fairly tolerant of overvoltage to a small degree. They almost always have a voltage regulator or a few of them right at the input. Their current draw is also very minimal. I should check a wireless router but I would expect them to only draw a couple of watts.
Also, in my experience cheap power adapters are only good to about half their rated amperage before they start getting a lot of ripple and voltage drop.
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