A cheap DRO from photographic film
Posted by
ibewgypsie
on 2004-02-19 02:15:14 UTC
Years ago, I made a linear encoder that worked quite well. I used a
roll of photographic film and took pictures of patterns. I stretched
the film between two clamps in a piece of box tubing I had cut a slot
into, sliding in the box channel was a piece of slotted UHMw WIth my
emitter-detector pair. The movement caused the slide to stroke up the
length of the film. This was on a air over oil "cylinder" robotic arm.
Tuning the emitter detector pairs I had with resistors to get a 0,1 I
made a siloette aperture to sight through.
I got a hand drawing, nothing else these days. I am wanting one for my
lathe. YOU are aware that a parallel port can read encoders if not
busy, or a pic like the basic stamp. I have the software working for a
stamp here also. The return communication thou sucks since the stamp
talks in ttl and the computer is above that. It takes another chip,
the max232 to pump it up to levels where the computer can reliably
read them.
I can post a hand drawing if anyone likes. Even the cheap ones are a
little to expensive if you ask me.
A better ideal would be a binary 16 bit encoder with a binary to 232
convertor chip of some kind. This would give absolute position and the
ability to read it after power-off and on. If someone wanted to get
fancy they could have both quadrature on the low bit and 16 bit binary
on the rest of the 35mm film. (by staggering the emitter-detector
pairs on the low bit.)
David
roll of photographic film and took pictures of patterns. I stretched
the film between two clamps in a piece of box tubing I had cut a slot
into, sliding in the box channel was a piece of slotted UHMw WIth my
emitter-detector pair. The movement caused the slide to stroke up the
length of the film. This was on a air over oil "cylinder" robotic arm.
Tuning the emitter detector pairs I had with resistors to get a 0,1 I
made a siloette aperture to sight through.
I got a hand drawing, nothing else these days. I am wanting one for my
lathe. YOU are aware that a parallel port can read encoders if not
busy, or a pic like the basic stamp. I have the software working for a
stamp here also. The return communication thou sucks since the stamp
talks in ttl and the computer is above that. It takes another chip,
the max232 to pump it up to levels where the computer can reliably
read them.
I can post a hand drawing if anyone likes. Even the cheap ones are a
little to expensive if you ask me.
A better ideal would be a binary 16 bit encoder with a binary to 232
convertor chip of some kind. This would give absolute position and the
ability to read it after power-off and on. If someone wanted to get
fancy they could have both quadrature on the low bit and 16 bit binary
on the rest of the 35mm film. (by staggering the emitter-detector
pairs on the low bit.)
David