<ericxdu>
Why do you need 2A to power the card via USB-OTG, put
<ericxdu>
But 7-21V to power the Microdesktop?
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<ericxdu>
Is that just a mis-match of ratings?
<arossdotme>
V=volts A=Amps
<arossdotme>
2A @ 5V
<arossdotme>
so for one number we times V*A=Watts
<arossdotme>
which you can then use to work out how many amps at 7-21V the micro desktop will take to power the cpu card
<arossdotme>
so...
<arossdotme>
ericxdu, ^
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<arossdotme>
lets say hmm heck, lets say your putting 19v into the micro desktop just cus ya got a laptop power supply that does that
<arossdotme>
so back to the cpu card, working out the watts
<arossdotme>
btw the 5V in "2A @ 5V" is cus that is the voltage of usb
<arossdotme>
5V*2A=10W
<arossdotme>
10W÷19V=
<arossdotme>
0.526A
<arossdotme>
so cpu card powered via otg-usb or mirco desktop its the same amount of total power
<arossdotme>
0.526A*19V=
<arossdotme>
10W
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<ericxdu>
Ah, maths. I think I get it now
<ericxdu>
I think the supply I'm looking at is 12v 1.5a so... let me math real quick
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<ericxdu>
Comes out to needing .83 amps
<ericxdu>
I'll check again when I have the cable with me... may have misremembered the voltage
<arossdotme>
not that you cant connect a power suppy more than 5v to the usb-otg power input on the card other wise you will damage/blowup your cpu card
<arossdotme>
not=note
<arossdotme>
re Amps, as long as if supplys 2A or more your ok. heck it could be 50A and thats np as long as its 5V
<arossdotme>
but its its 1A at 5V that wont be enough to reliably power the cpu card
<ericxdu>
arossdotme: I have the right charger for powering via usb... its a 5v 2a I found I was using for my phone
<ericxdu>
So I'm trying to find one for the microdesktop housing in case I get one
<arossdotme>
so with the microdesk top as long the Voltage of the power supply is with in the range can supply enough current which can be worked out by doing 10W/$PowerSupplyVoltage and if it is the same or more than the current/Amps rating of the power supply then your good to go
<ericxdu>
I like options
<arossdotme>
ericxdu, cool
<arossdotme>
btw by range i mean =7-21V
<ericxdu>
arossdotme: okay I'll use that rule of thumb when I check my supplies