I am working on a project which is supposed to control 220V-AC devices by the help of relays and Arduino through web browser interface.
Anyways, the project now requires me to diagnose if controlled device's current source is working so for that I am planning to connect AC/DC wall-wart to the circuit and use the DC it generates to check the presence of AC in the circuit by connecting the DC output to the Arduino pins.
So I have two unused phone chargers: Nokia AC-8E which produces 5V/890mA DC, Samsung ETA3S31EBE which outputs 4.75V/550mA DC.
As I am not an electronics savvy, I am come here with a simple yes/no question:
Do I need to add resistors or any other stuff to the circuit so that the wall-wart can be used together with Arduino safely on it's analog/digital inputs to check the presence of AC in the circuit?
By having this question answered I will know for sure that whether it needs more research on my part to make it work. Of course, it would be nice if someone answered with more detail, but everyone's time is precious so 'yes/no' will be more than enough.
I take it those wall-warts are already packed with protection in case of their failure to protect the devices, so the only thing I am not sure of is how Arduino pins will handle the current. Will they draw only the amount it "needs" or is 890mA/550mA too much? Because all I know is that Arduino pins can provide 20-30mA and draw 50mA at most, but I found nothing regarding how much current it can handle when the pins are used as inputs.
Excuse my ignorance. :)
Thank you very much.