a little diff question, have googled to get clues but apparently I don't know what exactly to seats for.
Im trying to turn on a led with arduino when a external source triggers 12v. basically that ext source swaps between 12v when active and 11v when inactive. I hoped for that 11v to be 0v so I could use transistor or relay with arduino but unfortunately the low state on external device is 11v.
how can I check with arduino when the ext source is at 11v and how do I tell arduino that this is the low state. I just want to light up a led with arduino whenever the ext source is 12v and kill the led light when it's 11v. I tried with 2 1M resistors on that 11v but I got it down to 9v and I don't like the idea of chaining resistors.
is there any other possible components that I could use for this purpose ?