I trying to create a digital turbo meter to my auto. But I having dificulties.
First, I mounted a circuit identical to this (instrumental amplifier) to read data from pressure sensor: http://www.practicalarduino.com/schematics/water-tank-depth-sensor-schematic.jpg
So, using multimeter, it's allright. Vout is perfectly that I want, amplified and inside arduino analog input range (0-5v).
But, when I plug Vout on arduino, it's don't works. :(
Using multimeter, connecting red picker to circuit Vout and negative picker to GND on arduino board, I have 0v (zero volt).
Otherwise, when I plug red finger to Vout and black finger to negative of my external supply voltage, it's perfect (~0.9v to 2.2v)
I'm confused. Because the instrumental amplifier have only 1 positive output...
thanks in advance.
- sorry by my english.