I've been prototyping a hall effect sensor board during the holidays with a bunch of components purchased off ebay.
This kind of sensor can detect the presence/absence of a magnet. They don't actually need to contact the component in motion.
The
A3144 sensor has an input voltage range of 4.5 - 24vdc. The board is designed to work off a 5volt supply voltage.
I ordered some 15mm (outer diameter) N45 neodymium magnets with a hole through the center that you can rivet/screw through. They trigger the sensor at about 0.5" away. Sensing range will depend on the strenngth of the magnetic field produced by the magnet.
If anyone needs/wants a BOM let me know and I can put something together. Nothing real special here though.
All discretes are 0805 surface mount components.- 1x 10uF capacitor for decoupling.
- 2x green LEDs
- 2x 180ohm resistors
- 1x female right angle header (0.1" pitch)
- 1x A3144 hall effect sensor.
The board can be ordered from OSHWPark
here.
I haven't tested this PCB out, but have built a number of boards by hand with the same schematic.
All source files are
here.
Note, if you're interested in this kind of sensor, but don't want to build your own, there's one sold on WCP from FRC971
here (not sure where the description and images went - new site?).