I need to connect an Arduino to an an automotive system so I can monitor temp, voltage, and rpm.
I know this is a crazy environment so I will be needing input protection for when I interface with the cars electrical system.
I have been reading and learning a lot since I started, but I am not sure if I covered all my bases for preventing the arduino circuit from frying.
Here is what I have thought of so far.
Here are the extreme conditions that I will need to cover.
Voltage divider for the battery monitor circuit will step input voltages of up to 18V to fit within the required 5V envelope.
A steady battery "boost jump-charging" input of 24V would result in 1.525V getting shunted to the 5v rail via D1.
Why would this work. Wouldn't the 5V rail be lifted to 6.525V instead and wouldn't this kill the arduino ?!?!?
125V (400ms ~10J) load dump --> shunted to 5V rail.
Can the rail disappate 10J of energy ??
300V (1J) transient --> shunted to 5V rail and the 1J of energy shouldn't be enough to raise the rail voltage
-100V alternator decay field. Any negative voltages should be eliminated from entering arduous circuit via D2
The programming part was easy, but I am a little over my head in protecting this circuit from failure. Can someone give any tips???
All help or insight is appreciated~!!!