I need to be able to measure resistances in the 0.1-10ohm range. My configuration is working well, but it leaves a little room for improvement in resolution.
+5V ------ 40kohm ---+-- 10kohm ------ 0V | test_resistance (can float from 0ohm to infinity) | 0V
If I set the analogReference to INTERNAL and measure at '+', a value of 3 or 4 indicates a test resistance of about 1.5ohms. This is good sensitivity, but if I could tolerate a much higher voltage (say, 4.5V) on that input pin while using the internal analogReference, without damaging the arduino, I would replace the 40kohm with a 1kohm and see a 4.5x increase in resolution.
Safe or Stupid? (Or... "Who let this guy on the Internet?")