Hall Sensor setup (more info and pics)

Hi again,

I have attached a new jpg to show the full circuit. What is supposed to happen is that the 5 rotating magnets trigger the Hall Sensor 5 times per rotation such that a current flows through the MOSFET and coils creating a magnetic field in each solenoid. When the current shuts off suddenly (as each rotor magnet passes the sensor) the field collapses and creates a high back emf pulse that is fed through the 3 diodes to the battery. I can look at those on a scope for my research purposes.

Three of the coils are wound on one coil of ‘litzed’ wire (nearest camera) and the others are on their own spools and all have a steel core. The Hall sensor position is attached to the front of the spool with the 3 coils on it and shown in one pic and the whole assembly in the other pic (Back EMF Generator).

If you think the circuit will not do what I am hoping would you be able to suggest how to modify it?

Any help would be appreciated. :slight_smile:


As I currently understand it when a mag field is absent the transistor is on (as Pin 3 is high) and the collector low which switches off the MOSFET so no current can flow in the coils. When a magnet approaches the tranny switches off, the collector goes high which switches on the MOSFET so current flows in the coils.

That depends if the hall sensor is normally high or normall low output.

Why not use a 555 or similar to generate the pulses if you want pulses?

Oh, I looked at the photo...

Hmm, how best to say this:

You are wasting a lot of copper on a wild goose chase?

And it litz wire, not "litzed"

In the absence of mag field the A3144E's output transistor is OFF (not conducting), when mag field present, transistor is ON (conducting), connecting collector to ground, Google "open collector NPN transistor switch".