I've looked all around on the internet and not managed to find anything really helpful, so I'm asking here, on the hope that somebody knows how to help me.
First, the outline:
I've got a pocket watch case. It has a winding stem. I want to sense the rotation of the winding stem, including speed and direction. Basically, I'd like an *absolute* position rotary encoder, but I can't even find any mechanical encoders that will fit inside the case.
I want to try making a rotary encoder out of some kind of magnet attached to the shaft of the winding stem and a hall effect sensor. I would like to use one, or no more than two hall effect sensors (SOT-23 or smaller) to achieve this result. What solutions are there, and how would I go about fabricating it and programming it? I would like to know the absolute position of the stem if possible, but if not, just the speed and direction of rotation would be nice.
Remember, this has to be *small*. Like *really really* small.
Oh -- and it can't cost a fortune. Basically, a simple $1-2 chip or two and a cheap, small magnet or two. Something like the Allegro A1230 seems like it should do the trick, but I'm not sure if it will be enough just by itself, nor how to actually construct the rotation-sensing assembly.
If anybody can point me to a document or three, or provide some shared experience or advice, I would really appreciate it.
Thank you.
First, the outline:
I've got a pocket watch case. It has a winding stem. I want to sense the rotation of the winding stem, including speed and direction. Basically, I'd like an *absolute* position rotary encoder, but I can't even find any mechanical encoders that will fit inside the case.
I want to try making a rotary encoder out of some kind of magnet attached to the shaft of the winding stem and a hall effect sensor. I would like to use one, or no more than two hall effect sensors (SOT-23 or smaller) to achieve this result. What solutions are there, and how would I go about fabricating it and programming it? I would like to know the absolute position of the stem if possible, but if not, just the speed and direction of rotation would be nice.
Remember, this has to be *small*. Like *really really* small.
Oh -- and it can't cost a fortune. Basically, a simple $1-2 chip or two and a cheap, small magnet or two. Something like the Allegro A1230 seems like it should do the trick, but I'm not sure if it will be enough just by itself, nor how to actually construct the rotation-sensing assembly.
If anybody can point me to a document or three, or provide some shared experience or advice, I would really appreciate it.
Thank you.