Contact less distance sensor with high accuracy.

I currenty use a potentiometer value to an analog port of the UNO for the trigger of a slot race controller. It works but............... I like to make it contactless to reduce all possible slack and other issues in the end. We need to sens movement of a rotational object that does an angle of 40 degrees max. So the further away the tip of the trigger end the higher or less a proprotional value should become.

A magent/induction solution would be OK. Something that measures magentic field proportional to the distance of the small magnet to the sensor. Any options to achieve this?


Can't you use an encoder? That should be long lasting, or some proximity sensors if you don't need to reed the whole movement.

For the magnetic... I know truck has a lot of those things (a little expensive)

I need the whole travel of the movement of the trigger to be read. Proximity if is accurate at mm distances it should work but I know it is not. I looked in that already.

I already have been thinking to use an arc of IR receivers LED where a IR LED is hoovering over but that limits my number of steps from 0 to max.


The magix words seems to be "ratiometric linear hall effect sensors".

I will do some more research on them and to see if their response time is quick enough to move a small magnet to and from the sensor for reliable analog readings.


backbone: I like to make it contactless to reduce all possible slack and other issues in the end.

A few ideas:

  1. Slotted photo-sensor with a disc/quadrant with varying degrees of transparency in a radial fashion
  2. Measure frequency change (in some manner) using a variable capacitor
  3. Measure signal phase-angle change using a variable AC transformer design

The first two will probably be easiest to investigate; the third would likely be difficult to make, as such adjustable transformers aren't easy to come by in small packages. Although, maybe you could hack in some manner a small IF "can" transformer (used to be use in RF/radio circuits - they, and variable capacitors have tended to becoming more difficult to find as the years wear on).