How do you know what power cable to buy?

[Aaralli]

We all lose important things sometimes... In my case, I lose power cables for all sorts of devices. I accidentally lost the cable for my modem, used a less powerful one that fit the plug, and killed it over the course of several months. My question is this:

How should I (and anyone who has this issue) go about finding the correct cable, adapter, plug, whatever, to replace lost ones? My current lost cable is one for an HDMI input splitter and audio extractor, and it actually says 5V on the back near the plug, but nothing about amperage.

This is the item I'm taking about:

https://www.amazon.com/dp/B083WVFZBP/ref=cm_sw_r_cp_apa_fabc_HNRMC4WZ3Q61E2FBNHJ6

[Enderman]

The amperage just needs to be equal to or greater than what the device requires.

The voltage needs to be the same.

[AndreiArgeanu]

One of the images on the amazon page says that the power supply provided provides 2A at 5V. So any power supply that supplies 5V and at least 2A or more will work with this.

[Aaralli]

3 minutes ago, AndreiArgeanu said:

One of the images on the amazon page says that the power supply provided provides 2A at 5V. So any power supply that supplies 5V and at least 2A or more will work with this.

Oh thank you, I guess I should've thought to look at the rest of the images. 

 

5 minutes ago, Enderman said:

The amperage just needs to be equal to or greater than what the device requires.

The voltage needs to be the same.

Why is it that you can have a power supply with more amps than necessary? I know tech usually pulls power, not push, but there isn't some danger to my electronics at all with too many amps?

[AndreiArgeanu]

3 minutes ago, Aaralli said:

Why is it that you can have a power supply with more amps than necessary? I know tech usually pulls power, not push, but there isn't some danger to my electronics at all with too many amps?

If your device is pulling more amps than necessary chances are it's malfunctioning so chances are, as long as you don't use a crappy power supply you're fine.

[Enderman]

3 minutes ago, Aaralli said:

Oh thank you, I guess I should've thought to look at the rest of the images. 

 

Why is it that you can have a power supply with more amps than necessary? I know tech usually pulls power, not push, but there isn't some danger to my electronics at all with too many amps?

Because how many amps can flow depends on the voltage you provide and the resistance of the load.

In order to push more amps you need to either decrease the resistance or increase the voltage.

If you give it the appropriate voltage that is listed on the device then the resistance is enough to regulate how much current it gets.

[Aaralli]

Just now, Enderman said:

Because how many amps can flow depends on the voltage you provide and the resistance of the load.

In order to push more amps you need to either decrease the resistance or increase the voltage.

If you give it the appropriate voltage that is listed on the device then the resistance is enough to regulate how much current it gets.

Yet another reason I rely on people like you to help me out... I understood very little of that

[tkitch]

48 minutes ago, Aaralli said:

Yet another reason I rely on people like you to help me out... I understood very little of that

Closer to an ELI5 answer:

Power bricks are rated for how many Volts they output, and how many Amps they *can* produce, at max.

 

So, a 12V Power brick always produces 12 Volts.

 

But if that brick is rated for 5 Amps?  It will only produce 5 Amps if the device is asking for that much power.  If it's asking for 2 Amps, it only outputs 2 amps.

 

Your device that is 'rated for 2A' is probably only using ~1 Amp most of the time, because 2A is the max it'll use.

 

It's kinda like a Faucet in your sink.  It has a maximum flow rate, but most of the time you don't turn it up all the way.  Your device using the power is controlling how much juice it wants coming from the brick.