power 12v dc motor with 5v dc source

Thread Starter

Mohamed Bouakoura

Joined Aug 26, 2015
6
hello everyone, .. i have a fan (12v , 0.16A) and i would like to power it using the USB port , which provides almost 5v
so any ideas how i can make it.

I tried to connect the USB source to a battery (9v) and the battery to another USB , it means two USB sources with the battery in between, (they are connected in series ) but this doesn't give nothing !

thanks a lot for your answers in advance.
 

dl324

Joined Mar 30, 2015
16,788
hello everyone, .. i have a fan (12v , 0.16A) and i would like to power it using the USB port , which provides almost 5v
so any ideas how i can make it.
This is a bad idea. You don't mention which USB protocol you're using, so this is worst case... USB 1.0 specs state that a device can draw 100mA from the port without negotiating for more, up to 500mA. Unintelligent devices that can't negotiate with the host are called client decorations and are limited to 100mA. You can't get 12V @ 160mA from 5V @ 100mA.
 

mcgyvr

Joined Oct 15, 2009
5,394
This is a bad idea. You don't mention which USB protocol you're using, so this is worst case... USB 1.0 specs state that a device can draw 100mA from the port without negotiating for more, up to 500mA. Unintelligent devices that can't negotiate with the host are called client decorations and are limited to 100mA. You can't get 12V @ 160mA from 5V @ 100mA.
I forgot USB 1.0 is only 100mA... been so long since I've seen USB1 ports.. But who knows what the OP has
 

dl324

Joined Mar 30, 2015
16,788
I forgot USB 1.0 is only 100mA... been so long since I've seen USB1 ports.. But who knows what the OP has
It's 100mA for USB2 and 150mA for USB3. The max current for USB2 is also 500mA, but went up to 900mA in USB3. However, clients need to be able to negotiate with the host for current greater than 1 "load". Voltage tolerance also changed with each USB version...
 

mcgyvr

Joined Oct 15, 2009
5,394
It's 100mA for USB2 and 150mA for USB3. The max current for USB2 is also 500mA, but went up to 900mA in USB3. However, clients need to be able to negotiate with the host for current greater than 1 "load". Voltage tolerance also changed with each USB version...
Yeah I though thats the "per unit/load" (or non-negotiating unit) current rating.. With negotiation (if you ask the host permission) you can pull more.. seen 1.5A up to 5A
 

Dr.killjoy

Joined Apr 28, 2013
1,196
Yeah I though thats the "per unit/load" (or non-negotiating unit) current rating.. With negotiation (if you ask the host permission) you can pull more.. seen 1.5A up to 5A
Is that good to push that much current threw the USB and is it safe or can be used a long time ??
 
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