USB power mod - wall adapter and cable

[xhul]

Welcome!

 

I recently purchased an USB power mod kit, and i would like to use it with a wall adapter.

From what i understood, at least 1A is required.

 

Regarding the wall adapter, the one i may get provides 12W.

If i'm not too bad at maths, that would mean 2.4A.

Would that be too much, or would the lynx only get what it needs from it?

 

About the cable i should be looking for, i'm more confused.

In my case, i'm looking for USB-A male <> micro-USB male.

It appears most of those cables are USB-2.0 ones.

The thing is, i've read that USB-2.0 isn't supposed to go above 500mA, but at the same time, i've read that some can reach a lot more, with the proper AWG...

 

Thanks in advance for your time =]

[+Stephen Moss]

Any electronic circuit will (barring a fault) only draw as much current as it needs, so a power source that can only supply less than 1A would be bad, but one that can supply more is fine provided the voltage is regulated which is should be for USB.

 

The 500mA limit should only really apply to a USB port on a PC and is the maximum anyone peripheral can take although it may not get that depending on the negotiation with the host.

This should not really apply to a USB power source that is built into a mains power outlet as they are generally dumb devices with no USB host for negotiating current, although that may be different with some USB chargers it would seem unlikely as it would have to be intelligent and recognise what was plugged into it to negotiate current usage with the device. So provided it is rated as being able to supply 1A or more then generally you should be able to get 1A from it.

 

If you are worried about the cables current carrying capacity you can try and look for one that has a high current rating but that is not a generally provided specification but they will be rated to whatever the set out in the USB Documentation at USB.org.

I think USB 3 has a higher rating that USB 2 but you would have to check with the documentation, that said any decent cable should have spare capacity therefore if a USB 2 device is limited to 500mA the cable can probably handle 1A. At worst taking 1A down a cable rated for 500mA would mean there would be a slight voltage drop across the cable and the cable may be heated slightly by the resulting power dissipation but I would expect both to be too small to really notice.     

[xhul]

4 hours ago, Stephen Moss said:

Any electronic circuit will (barring a fault) only draw as much current as it needs, so a power source that can only supply less than 1A would be bad, but one that can supply more is fine provided the voltage is regulated which is should be for USB.

 

The 500mA limit should only really apply to a USB port on a PC and is the maximum anyone peripheral can take although it may not get that depending on the negotiation with the host.

This should not really apply to a USB power source that is built into a mains power outlet as they are generally dumb devices with no USB host for negotiating current, although that may be different with some USB chargers it would seem unlikely as it would have to be intelligent and recognise what was plugged into it to negotiate current usage with the device. So provided it is rated as being able to supply 1A or more then generally you should be able to get 1A from it.

 

If you are worried about the cables current carrying capacity you can try and look for one that has a high current rating but that is not a generally provided specification but they will be rated to whatever the set out in the USB Documentation at USB.org.

I think USB 3 has a higher rating that USB 2 but you would have to check with the documentation, that said any decent cable should have spare capacity therefore if a USB 2 device is limited to 500mA the cable can probably handle 1A. At worst taking 1A down a cable rated for 500mA would mean there would be a slight voltage drop across the cable and the cable may be heated slightly by the resulting power dissipation but I would expect both to be too small to really notice.     

Big thanks, it clears up a bit more things in my mind.

The cable i saw is 3m-long with a nice 90° angle on the micro-USB side, but it's USB-2.0.

I guess i'll ask the seller for details specs, like max amperage|wattage, and AWG to be sure.

Could the voltage drop you were talking about actually affect the lynx itself?

[+DarkLord]

I installed that mod in my Lynx. Here's the cable I'm using and it works great:

 

https://www.amazon.com/dp/B0B66ZJ6NF?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

And here's the charging block I'm using:

 

https://www.amazon.com/gp/product/B07C2QG8BB/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

 

Lynx works great, no "blinking" lights, etc,...

 

HTH's. 

 

[+Stephen Moss]

On 2/3/2023 at 2:04 PM, xhul said:

Could the voltage drop you were talking about actually affect the lynx itself?

As I said in my original post, I expect it to be to small to have any appreciable effect, but it is there.

For a cable, 1 ohm of resistance is very high, particularly over such a short length. Evan at that resistance it would drop 1V at 1 amp, but at most I would not expect more than a 0.1V drop.

[xhul]

6 hours ago, Stephen Moss said:

As I said in my original post, I expect it to be to small to have any appreciable effect, but it is there.

For a cable, 1 ohm of resistance is very high, particularly over such a short length. Evan at that resistance it would drop 1V at 1 amp, but at most I would not expect more than a 0.1V drop.

Thanks again =]

 

I just need to wait for the adapter & cable to arrive now.

It's a bet for the cable, since the vendor himself didn't know the actual specifications.

I also hope the 90° angle on the micro-usb side is gonna fit.

Will let you guys know how it went.

[xhul]

Back from holidays-at-work, so i was finally able to test everything, and it appears to work fine =]

For the record:

wall adapter : USB A female | 12W

cable : USB A male <> micro USB B male | 3 meters (no switch)

Haven't installed the female port yet, but according to the measurements, the 90° angle near the micro USB side of the cable should fit just fine.

So the cable turns down, so it won't bother my left hand when playing, while still being able to put the lynx on a flat surface.

I wish i could throw a photo, but as a time-traveler, we don't have "smart" phones where i come from, sorry about that.

Big thanks to everybody for the technical advice!