Hi all,
Again, thanks for all the replies!
Back to my window opening measurement needs!
I found an old digital caliper I had, and decided to see how they did it.
This is what I found, and need some 'splaining
#1. One circuit board. #2. One Pic type ic covered in black goo #3. One chrystal, 153.6k(?) #4. No physical mechanical measuring system (pots etc) #5. Noticed that on the underside of board, where the board touchs the printed ruler on shaft, there are 8 lines from the chip there. Let me try to show the layout in ascii!
+------+ o--------o--------o--------o---------o---------o-----| PIC? | o--------o--------o--------o---------o---------o---------| | o--------o--------o--------o---------o---------o------| | o--------o--------o--------o---------o---------o----------| | o--------o--------o--------o---------o---------o-------| | o--------o--------o--------o---------o---------o-----------| | o--------o--------o--------o---------o---------o--------| | o--------o--------o--------o---------o---------o------------| | +------+The "o"'s are physical holes in the cb
#6. Now the strip that these touch, or nearly touch is the "ruler" part. This is where is shows 10...20...etc.
#7. I noticed that when the below cb with the pattern on #5 slided on this strip, the values change!
#8. I removed the sticky tape that was the "ruler" printout and found another circuit board, this is the long ruler part. On this board there us a square wave pattern running down the whole side.
Ascii
-----+-----------+-----------+------... | | | | | | +--+--+ +--+--+ +--+--+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
--+ +-----+ +-----+ +--- ... and so on
The rise and fall of the wave are the same length
The top cb slides on this pattern. The pattern in etched(?) printed(?), and the copper of the CB is all there.
Question:
What the heck is this?! I'm guessing that somehow the 8 lines can detect a voltage change(?) to determine movement?
and yes, there is no true zero point, just an increment/decrement of a known resolution from a starting point!
I want to make this! how?
Any thoughts?
~Kam (^8*