2168 A3144 Hall effect sensor board

[mman1506]

Why did you choose to use a through hole limit switch over an SMD one? Also aren't the A3144 discontinued?

[electroken]

Originally Posted by mman1506

Why did you choose to use a through hole limit switch over an SMD one? Also aren't the A3144 discontinued?

The A3144 is indeed discontinued. Allegro Microsystems A1104 should drop right in for our purposes.

[otherguy]

Originally Posted by mman1506

Why did you choose to use a through hole limit switch over an SMD one? Also aren't the A3144 discontinued?

The only reason I used through hole components was because that's what I have on hand. I'm making these boards for testing purposes. If we find we link the sensors and could use more, it would certainly make sense to use all surface mount components as it would prevent there being any conductive components on the bottom of the board, making it easier to mount.

You're right, the A3144 component is a discontinued part, but they are widely available online (search ebay for hall effect sensor). I'm assuming they are clones from China, but the parts I've been using all seem to be workign correctly. If the supply actually dries up, its easy enough to spin a new version of the board. Obviously if I were trying to build a product for sale, I wouldn't be so recklessly sourcing components.

You may want to add one or two (better) mounting holes.

There is a hole right down the middle of the board. I agree though two holes would be preferred. As it is currently implemented, the board may rotate, but I'm betting friction will be sufficient to keep this from moving. We will see.
I was playing with the idea of having two hemisphere cutouts on the side of the board, allowing two screws to sandwich the board between them, but didn't have time to verify that the way I knew how to do it in Kicad would actually meet the fabrication guidelines on OSHWpark. I didnt want to add another screw hole with keepout as it would increase the board size. I was trying to keep the board as small as possible.

Can someone who has used the 971 board or something similar like this comment on how accurate and repeatable they are?

I cut up a bit of video I took of one of the prototypes in action. It's pretty accurate, but you can see for yourself if you think it's good enough.
http://youtu.be/6Dsre-IwP_I