Laser toner is good for this. You could get a shiny metal disk, print your
encoder onto transparency on a laser printer, and stick it together. Ensure
the toner side of the transparency is on the outside- the other side of the
transparency may reflect.

-----Original Message-----
From: Peter Moreton [mailto:peter@RIL.ORG.UK]
Sent: 15 September 2003 12:01
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]:Homebrew Opto Encoder advise pse.


Mike,

You 'black' spirit pen may be black in the visible wavelengths, but may be
quite reflective in the IR band. You just have to find a black paint/ink
that absorbs IR. Since your eyes cannot detect IR, this is difficult!

Maybe try various pieces of card painted with various black inks/paints, and
see which ones reflect the IR from your TV remote control? Or lay them out
in the sun, and see which ones get hot (= absorb IR)

Regards, Peter Moreton



-----Original Message-----
From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU] On
Behalf Of Mike W
Sent: 15 September 2003 10:05
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]:Homebrew Opto Encoder advise pse.

GM folks,
I'm trying to find the 'proper' stuff to make a reflective opto quadrature
rotary encoder.  I'm having problems in as much as the black ( spirit based
felt tip pen ) is reflecting as much IR as the white

Please share your experience ..

I'm using an old VCR head for the mechanics, with two OPB706a reflective
opto couplers as the detectors. they are mounted inside the head assembly
and shine on the inside of the VCR head which has a computer drawn wotzit (
can't think of its name ) stuck on the head. spaceing is about 1mm from
opto's to wotzit.

thanks v much
mike

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