rough guess of amper rate

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quamenzullo
 
Posts: 19
Joined: Thu May 15, 2014 11:42 am

rough guess of amper rate

Post by quamenzullo »

Hello,

I would like to use a 220V -> 12V adapter to power my raspberry pi. I would like to know roughly how much power it requires. Really roughly, just to know if I have to find a 3 A adapter or if a 1.5 A of 2 A would be enough.

Details : the project uses
- a LCD and keypad kit https://www.adafruit.com/products/1110
- and a wifi dongle (https://www.adafruit.com/products/814).

The other project's components that I am not sure they use power at all:
- a power switch https://www.adafruit.com/products/1400,
- a rotary encoder https://www.adafruit.com/products/377,
- a unit from mausberrycircuits (this one http://www.mausberrycircuits.com/collec ... ply-switch).
- plus it outputs audio (mini audio jack)

Thanks for any hint!

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tseary
 
Posts: 27
Joined: Sun May 25, 2014 3:53 pm

Re: rough guess of amper rate

Post by tseary »

The Pi consumes only 1 A if I recall.
The LCD and keypad could use up to 60 mA for the backlights (at full brightness white), so we'll round up to 0.1 A.
The wifi dongle will not use more than 500 mA since that's the limit for USB.
The power switch and rotary encoder are passive, so 0 A.
The Mausberrycircuits unit doesn't look like it uses much power, but it should be able to supply 500 mA to each USB port. Check the datasheet if it's available.
The current from the audio jack is negligible.

The total estimate is 1.6 A plus the load on the Mausberrycircuits unit. Therefore, a 2 A supply is suitable, and a 1.5 A supply would probably be sufficient unless you're doing a lot of heavy processing.

quamenzullo
 
Posts: 19
Joined: Thu May 15, 2014 11:42 am

Re: rough guess of amper rate

Post by quamenzullo »

Thank you very much!

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