Voltage and current the arduino needs

Other Hardware General Electronics
1

Hello,
i am facing a problem concerning the power supply of the arduino Ethernet board. I am using the 5V power supply of the pc power supply which gives current even when the pc is off(purple cable). The problem is that when i measure the voltage on my board i take 4,2V and not 5V. If i use arduino's power supply the same measurement gives 5,02V. This makes my board unstable. The problem is that i do not know if this is due to low voltage or low current supply. As far as i know the pc power supply should have no problem providing adequate current to arduino. Are there known voltage and current thresholds concerning the appropriate functionality of the board?

Any info or suggestions are more than welcome. I am using arduino on custom pc deployment and i am limited when it comes to current supply.

Thank you all in advance,
ioigoume

2

That wire can't supply enough current, that's why you get the voltage drop.

3

The USB power makes it unstable? USB is only good for 500mA.
Power availalble via barrel jack is 800mA.

4

ioigoume:
Hello,
i am facing a problem concerning the power supply of the arduino Ethernet board. I am using the 5V power supply of the pc power supply which gives current even when the pc is off(purple cable). The problem is that when i measure the voltage on my board i take 4,2V and not 5V. If i use arduino's power supply the same measurement gives 5,02V.

That's not clear - what is "my board"?, how are you connecting the purple wire? What do you mean by "arduino's power supply"?

5

Thank you all for the clarifications! I will try to find different ways to power the arduino.

ioigoume