Let's Make Robots!

locomotive

Hopefully pulls me round the track :)
Lumi requested that I post about this ongoing project of mine.  I am currently about half way through builing a working 3 1/2" gauge live steam locomotive.  This … Read more

Question - Rev counter

For this project here http://letsmakerobots.com/node/22474, I am needing a simple sensor to indicate the number of revolutions a tsecond that an axle makes.  However this will be in a dirty/oily place (under isde of carriage bogie) so I am wondering on the best method of sensor to use.  I think I have narrowed it down to three possibilites -

1/ Optical slot interupter with seperate encoding wheel.  Probably easiest option but how prone to dirt and mis reading.  Could be hard to clean.