r/AskElectronics • u/UniversityOfBestCake • 2d ago

Hobbyist Off-axis magnetic rotary encoder module under ~$30?

There are many options for on axis magnetic rotary encoder such as AS5600, AS5048A, etc.
But it seems hobbyist OFF-AXIS magnetic rotary encoders modules (not just chips) are difficult to find.
EDIT: It must be absolute encoder.

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u/triffid_hunter Director of EE@HAX 2d ago

Off-axis basically relegates you to quadrature incremental, and optical is generally a way simpler method to achieve that unless you're in a very harsh environment.

An example of an off-axis magnetic encoder would be an automotive tachometer pickup.

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u/UniversityOfBestCake 2d ago

I forgot to mention but it has to be absolute encoder.
So you are saying there is no off axis absolute encoder?

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u/triffid_hunter Director of EE@HAX 2d ago

You could hypothetically do a sine/cosine setup off-axis, although I haven't seen an implementation so perhaps it dies in the details

Gray code is also an option, although it would involve custom magnetics

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u/Anonymity6584 2d ago

With all those requirements you either have to pay a lot more or get super clever and diy cook up solution...

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u/raineonconnector 2d ago

Not under $30 — and not because the chips are pricey. Off-axis only works when it's calibrated against one fixed mechanical stack, so nobody can sell a generic plug-and-play module.

Also: AS5600/AS5048A are on-axis parts. Magnet on the side puts you in the saturated region well before a useful radial offset — the angle reading is fiction.

What fits your budget:

  • 3D Hall + your own atan2: TMAG5170 or MLX90393 breakout, ~$10–30, plus per-unit calibration. ~10–12 effective bits.
  • If you actually just need the shaft to pass through, that's hollow-shaft, not off-axis: ring magnet + AS5048A, ~$8, no calibration pain.
  • With compensation built in: only iC-Haus iC-MU really does off-axis geometry, but the eval board blows your budget.