reading low-voltage AC voltage?

I want to read/measure a low-current AC voltage source (from a spinning brushless DC motor). Is this possible to do from an Arduino without much extra circuity? Specifically I want to build the anenometer located here, but want to know if I can somehow dispense with the LM2917 circuit and measure the AC voltage directly instead.

hi

in the article you linked to, the LM 2917 is actually doing frequency-to-voltage conversion… Looks like a robust and accurate way to do it. You could go with a few diodes and a capacitor ( i.e. ac-dc conversion), but you would lose the frequency, which presumably represents how fast the motor is turning. The best thing might be to just use their design, but repolace the meter with an Ardiuno analog pin.

D

hi

in the article you linked to, the LM 2917 is actually doing frequency-to-voltage conversion… Looks like a robust and accurate way to do it. You could go with a few diodes and a capacitor ( i.e. ac-dc conversion), but you would lose the frequency, which presumably represents how fast the motor is turning. The best thing might be to just use their design, but repolace the meter with an Ardiuno analog pin.

D

Thanks this makes sense- I just wanted to make sure their wasn’t an easier way to go about this before I built the LM 2917 circuit.

hey

check the datasheet before you connect the Arduino… they will have some example circuits of how to use the 2917. It won’t be exactly the same as the diagram in the article, since the meter is measuring current flow.