Re: [CAD_CAM_EDM_DRO] Opinions: Hall Effect (digital output type) as limit switch???

Hi Lee,

What about optical interrupter type sensors? A pair of them is quite
cheap! One gets put on the axis, with a little vane to break it's IR
beam, and the other gets a vane that spins with the lead screw
(optional, improves accuracy for a HOME sensor). The two sensors are
"AND'ed" together with a little TTL logic.

Now that my Sherline moves a LOT faster, I'm thinking of putting them on
it. As soon as I can figure out how to mount'em!

I also have plenty of surplus Micro Switches, which would also work.
I'm thinking I'd like to have home switches as well. Should be able to
combine the functions!

For the "known problem" of power supply failure, with the proper
"logic", it might be possible to make them "fail open", that is to say,
if the power to the sensors fails, it causes a limit signal.

Alan KM6VV
P.S. I've seen Hall effect switches on some old 5.25" floppy drives,
That might be a source of cheap switches to experiment with.


studleylee wrote:

>
> Hi,
> With inductive proximity sensors being in the range of $60 each:(or
> are there cheaper ones out there?
>
> Opinions: Hall Effect (digital output type) as limit switches ???
>
> Ideas:
> Open collector outputs could be paralleled for redundency in placing
> 2 sensors in one package. Known Drawback: if sensor power
> supply fails.
>
> -Lee