How does Voltage Hall sensor anemometer work?

The typical Hall anemometer I get; magnet approaches sensor, voltage goes down; magnet regresses, voltage goes back up.

I have a Hall effect anemometer which is different. The voltage is proportional to the speed of rotation (0.4v - 2v). How does this work?

Is there a smoothing RC circuit? There is a lag between shaft rotation and voltage, but it doesn't quite seem like an RC.

How does it work?

Al

What anemometer? Maybe it does not use a Hall device. Some use a DC generator, which works exactly as you describe.

You have a point. I should take it apart first.

The friction is so slight, it cannot be driving any sort of generator.

I will disassemble it sometime. Perhaps it will be obvious after inspection.

I was hoping somebody knew the principle of operation.

ecarecar:
You have a point. I should take it apart first.

The friction is so slight, it cannot be driving any sort of generator.

I will disassemble it sometime. Perhaps it will be obvious after inspection.

I was hoping somebody knew the principle of operation.

We all thought you already knew what was in it. A generator at slow speed has imperceptible resistance. My anemometer uses a reed switch and magnet. No resistance at all.

My old one used a small motor and there was no speed resistance. Also no air speed indication at slow speeds. The reed switch will indicate < 1 mph.

Paul

The friction is so slight, it cannot be driving any sort of generator

Wrong again. I have two anemometers that use very small generators, and they turn in the slightest breeze.

An unloaded coreless brushless generator puts an immeasurably small load on the shaft, the bearing friction will dominate.

Jeeze, what a group.

OK, if y’all so smart, howz come it has a voltage of 0.4v at ZERO rpm?

OK, if y'all so smart, howz come it has a voltage of 0.4v at ZERO rpm?

Why should we believe you?

Are you shure that inside there is not an MCU?