i can't seem to find concrete info on this.
from what i gather, external power can be anything between 7-12VDC and with a positive center plug, is that correct?
is there a range for amount of current?
i have a 5VDC, 2.6A ac to dc adapter with a positive core plug that fits; it is below 7VDC, but would it work? i can just try it, but i am very weak regarding electronics knowledge (its why i am trying to learn) and don't wanna ruin the board.
i have a 5VDC, 2.6A ac to dc adapter with a positive core plug that fits; it is below 7VDC, but would it work?
No. The voltage regulator needs about 1.5 to 2V (depends on the regulator) and the reverse protection diode costs another 0.6V. If you plugged this in, it may seem to operate, but it would be operating on about 3V, wouldn't work correctly, and you may even trash your bootloader requiring reprogramming the ATmega.
If (and only if!) it is a regulated 5V supply, you could feed it to the Arduino into the 5V and ground pins on the small header. Many of these wall warts are not regulated, though, and would fry components of the Arduino.
-j
Would a non-regulated wall wart be ok if it falls between 7.5-12V, or is it bad regardless (your response makes me think non-regulated is more of an issue with a 5V supply)? So if I were to buy an AC-to-DC adapter, what would be the best voltage and amperage to get?
Sounds like a 7.5V adapter would be optimal. Not sure what the effect of different amperages are; what range of amps output is fine?
Thanks for the previous reply and any subsequent replies.
The MC33269DT-5.0G regulator on the official Arduino made in Italy is spec'ed for 0.8A MAX @ 5V output
If your project requires more power than that you need to use an external regulated power supply
The pins on the ATmega168 are spec'ed for 20 mA at VCC = 5V, 10 mA at VCC = 3V according to the datasheet
The sum of all IOH, for ports C0 - C5, D0- D4, ADC7, RESET should not exceed 150 mA.
The sum of all IOH, for ports B0 - B5, D5 - D7, ADC6, XTAL1, XTAL2 should not exceed 150 mA.
A normal unregulated AC adapter with output between 7-12V DC and 300mA to 1A should work for powering the Arduino using the onboard DC jack and accompanying MC33269DT-5.0G regulator
You should never supply unregulated power directly to the +5V and ground pins that kg4wsv was referring to
If you have an external 5V regulated power supply you could connect it to the +5V and ground pins
The limits mentioned in my previous post will always apply