USB Power

[Wind1000100]

Hello,

 

I could not find any subtopic to cover this and I didn't want to search for a whole different forum when I know this community is great and should be able to help/link me somewhere, so I'm putting my topic here.

 

I have been doing some testing with USB power. I have connected two cheap USB cables which used to have lightning connectors on the end to an old 12V fan. When I plug either of the connectors into a USB port, the fan starts spinning... However, when I plug both USB connectors into a USB port each, the fan continues spinning but no faster (the air doesn't feel faster and the sound does not increase, at least just based on hearing). Does anyone know if this can be done/if there is something else I need to do?

 

There are a few pictures of what I was doing on my Instagram page, if you want to see - https://instagram.com/wind1000100/

 

Thanks!

[Wind1000100]

Oh and yes, I have checked that both cables work on their own in each USB port.

[ofr057]

what version of usb are you running?

 

connecting multiple cables wont increase the voltage/ amps.  you a merely making so that the cable's have a redundancy .

 

I wouldn't try pushing a fan over 12v anyways since they wouldn't be tested for it and will become unbalanced.

[Blebekblebek]

power distribution shared to all of ports

USB 1-2 max 500mA

USB 3 Max 900mA

 

if you really want to max the fan spin you can try power it with phone/external adapter.

[Wind1000100]

what version of usb are you running?

 

connecting multiple cables wont increase the voltage/ amps.  you a merely making so that the cable's have a redundancy .

 

I wouldn't try pushing a fan over 12v anyways since they wouldn't be tested for it and will become unbalanced.

Front panel USB 2/3. Also the maximum output is 5v and they're front panel anyway, so the fan is running under voltage by a mile

[Wind1000100]

power distribution shared to all of ports

USB 1-2 max 500mA

USB 3 Max 900mA

 

if you really want to max the fan spin you can try power it with phone/external adapter.

But don't the phone wall adapters output 5 volts anyway?

[Wind1000100]

Thanks for the responses, if anyone knows how I can make the voltage be doubled, I'd appreciate it so much!!

[ofr057]

Thanks for the responses, if anyone knows how I can make the voltage be doubled, I'd appreciate it so much!!

if you want to start mucking around with power i would look at getting a cheap oscilloscope and a bench power supply.

something like these

http://www.rigolna.com/products/dc-power-supplies/

[Wind1000100]

if you want to start mucking around with power i would look at getting a cheap oscilloscope and a bench power supply.

something like these

http://www.rigolna.com/products/dc-power-supplies/

Is there any reason why I can't use an old PC power supply?

Also I just want to power 5-15 volts through USB for practicality and saving batteries.

[SIGSEGV]

Are you sure you want to run your fans any higher than 5v? I once ran my case fan off of a molex connector with 12v on it, it was unbelievably loud (you could hear it from the room next to it).

[dfsdfgfkjsefoiqzemnd]

The way you connected those ports is in parallel, to double the voltage you'd need to put them in series (more info on series vs parallel here)

However I'd advise against hotwiring an USB cable like that and will accept no responsability if anyone does so.  You just might blow up your system or burn down your house. 

 

If you really want 12V, the best option is to use an old PSU indeed.  You'll need to short 2 of the connectors on the 24-plug though, otherwise it'll deliver no power whatsoever. 

 

Another option would be a power adapter for an external HDD enclosure.  Most of those put out 12V.  I'm looking at one from an old (IDE) enclosure, and according to the label it puts out 12V 1.5A.

For 5V, any phone charger will do. 

[ofr057]

Is there any reason why I can't use an old PC power supply?

Also I just want to power 5-15 volts through USB for practicality and saving batteries.

if your getting into that stuff i would still recommend it since it is safer then hot wiring a old psu,

 

you will be able to run alot of other stuff off it aswell

[ofr057]

power distribution shared to all of ports

USB 1-2 max 500mA

USB 3 Max 900mA

 

if you really want to max the fan spin you can try power it with phone/external adapter.

I got done by a bad usb 2 cable the other day felt like a pin sticking into me

[mr moose]

Don't know if it's already been answered or not, but the reality of the situation is that more cables is not going to get more power, all your usb 5+v pins are connected together on the inside so it doesn't matter if you have one cable or 5 cables there is only one 5V supply.

[Wind1000100]

Are you sure you want to run your fans any higher than 5v? I once ran my case fan off of a molex connector with 12v on it, it was unbelievably loud (you could hear it from the room next to it).

A 12v fan running on 12v should be running at maximum speed. Also I'm only using a fan for testing purposes, it really doesn't matter about what it's connected to.

[Wind1000100]

However I'd advise against hotwiring an USB cable like that and will accept no responsability if anyone does so.  You just might blow up your system or burn down your house. 

I'm struggling to see how it would be unsafe to run a USB cable soldered to something else AND insulated with electrical tape to prevent any short circuits, plugged into a safe wall power output such as one provided by Apple, could be unsafe. Please explain!

 

Thanks for the information though.

[Wind1000100]

The way you connected those ports is in parallel, to double the voltage you'd need to put them in series (more info on series vs parallel here)

I used to understand series and parallel circuits (when I was eight to twelve years old), but I've worked more with computer hardware than basic electronics lately I'll read that link to re-inform myself.

[mr moose]

The way you connected those ports is in parallel, to double the voltage you'd need to put them in series (more info on series vs parallel here)

However I'd advise against hotwiring an USB cable like that and will accept no responsability if anyone does so.  You just might blow up your system or burn down your house. 

 

If you really want 12V, the best option is to use an old PSU indeed.  You'll need to short 2 of the connectors on the 24-plug though, otherwise it'll deliver no power whatsoever. 

 

Another option would be a power adapter for an external HDD enclosure.  Most of those put out 12V.  I'm looking at one from an old (IDE) enclosure, and according to the label it puts out 12V 1.5A.

For 5V, any phone charger will do. 

 

Not might blow up but will blow up.  You cannot link any of the power cables from a single rail PSU in series,  essentially all you would do is short them out.

[Wind1000100]

Not might blow up but will blow up.  You cannot link any of the power cables from a single rail PSU in series,  essentially all you would do is short them out.

Wait, running directly from a computer power supply or through two front-panel USB ports?

[mr moose]

Wait, running directly from a computer power supply or through two front-panel USB ports?

 

If you were to take the power from the two front usb ports and connect them in series you'd short out the PSU.

[dfsdfgfkjsefoiqzemnd]

If you were to take the power from the two front usb ports and connect them in series you'd short out the PSU.

Correct.  That's why I said I wouldn't recommend putting USB wires in series.  Due to all the circuitry involved, it's not the same as putting half a dozen 1.5V batteries end to end.  You will kill the PSU or whatever hardware gives up first.

[mr moose]

If you want 12v out side you case why no feed one of the molex plugs from your psu through the rear (pop out an expansion slot cap) and plug your fan into that? 

[Wind1000100]

If you want 12v out side you case why no feed one of the molex plugs from your psu through the rear (pop out an expansion slot cap) and plug your fan into that? 

Yeah, but I don't necessarily want to. The fan is only a test, I'll be using it for other things.

[Wind1000100]

I used a fan because it won't get killed like a light bulb or something, and the fan goes up to 12 volts meaning I have a lot of room to play with lower up to higher voltages.

[Mikeyj426]

You need external power not from a USB port if you want more voltage.