Itty, Bitty Hall Effect Limit Switches

A while back, I designed up some small Hall Effect limit switches for the Torus Pro. These use small (TO92) three-terminal Hall Effect sensors - the same kind I use in the Torus Pro PDB. They are inexpensive (under $1 each), and very accurate and repeatable. They are triggered by the South pole of a small (5mm dia x 1mm thick) Neodymium disc magnet. They can be triggered by pushing either end of the pushrod about 01", so can be setup to use only one switch assembly per axis, or two. The only part I haven't made yet is the "flags" that attach to the pushrod, and hold the disc magnet. The sensor itself is epoxied into a small pocket milled into the back cover, with the three wires, also epoxied in place, coming out the side. A pair of small coil springs provide self-centering of the pushrod and flag.

Here is the assembled view. The housing is three pieces - a 1/8" thick back cover, 3/8" thick center piece, and 1/8" thick front cover.

Attachment 252386

With the front cover removed, you can see the pushrod, the pockets on the left and right to locate the two coil springs, and the pocket in the back cover for the sensor and wires. The three housing pieces will be sealed with a good sealant, like Hylomar. The flag will be pinned to the center of the pushrod.

Attachment 252384

Regards,
Ray L.

OK I will take 3,...

What kind of accuracy are you expecting for homing/limits with these?

In playing with the sensors a few years ago, they appeared to be good to at least a couple of tenths.

Regards,
Ray L.

Ray;
Are you going to sell these sensors?
Kind of like the design.
Bill

Bill,

I have no interest in selling them, but I will post the models, and you can make your own. They're pretty easy to make.

Regards,
Ray L.