I'm trying to do just this, but its not working.
It worked GREAT on my old Bosch Colt. Now I want to implement it on my new 600w spindle.
I've got the parts made up, and thinking it would be a straight plug and play, it's not.
Seems like it is electrically interfering (shorting out) with the other electronics.
I have no resister in line, and honestly, not sure of the polarity (Going to double check tonight)
But if I can get this working. its a supper set up!
I have some pictures, but can't seem to get them uploaded.
I'll try uploading them again later(might be a work computer thing)
My Build: http://www.cnczone.com/forums/diy-cnc_router_table_machines/113711-my_build_-_many_thanks.html