jucasan:
They are probably too expensive and big for what I need. What would be the best option if I want to make my own. Infrarred, reflective, photoresistor?? I don't need anything super precise. Probably can laser cut a wheel and even use a reduction. If I can get a pulse every 4-5 turns of the DC motor is more than I need.Thanks
Are you looking to read RPM or control RPM via a servo loop?
If so, why not just color 1/2 of the shaft black (like with a paint pen) then just use an IR led and IR photo detector to pick up one pulse pre rev?
If you build an encoder wheel then use a reduction, you end up cutting your resolution by the reduction factor!
Say you make an 8 segment wheel and gear it down by a factor of 8. That turns it into a one pulse per rev encoder!