rotary encoder

American Science and SUrplus www.sciplus.com has a nice looking encoder for
sale:
Their copy reads:


Glass Encoder
Cory says this is a really impressive top quality optical glass electronic
encoder. And we believe him. Stegmann Product Number HD20, it emits 500
pulses per shaft revolution. We ask that you go to Stegmann's web site to
download all the technical information:
www.stegmann.com/product/incremental/dsheets.html. Or call us and we will
fax you one. Suffice it to say here that it has a service range max of 3000
to 5000 rpm depending on shaft load. Machinists and builders or users of
precision instruments will think they have died and gone to heaven when they
get this item at our surplus price!

19252 GLASS ENCODER $19.50 / each

these guys have lots of neat stuff, and I have no affiliation other than
being a satisfied customer...

Jim FAckert