Help! Finding small high resolution encoder

Hi.

I am doing a project where I need a high resolution (at least 200 P/R) rotary encoder. But it needs to be small. I have found this one, but it is actually too big for my design. I really need it to be compact.
http://www.ebay.com/itm/Bourns-ENT1J-D28-L00128L-EN-Model-Rotary-Optical-Encoder-2-Bit-Quadrature-Signal-/191134234168?pt=LH_DefaultDomain_0&hash=item2c807cf638

I am quite new to arduino and everything, so I dont know where to look. (I am actually not doing the arduino work, just finding the right components) I have searched around for days, without finding anything, and therefore I ask you for help. Hope you have some tips leading me in the right direction.

Hope you can help me! :slight_smile:

Lasse

Maybe you can tell us where in the world you are located (so we can know where to send you for vendors and suppliers) - as well as quantifying what you mean be "compact" (size, weight, dimensions, etc).

Also - it might help us help you if we knew what you needed the rotary encoder for (ie - what is your project and what is the purpose of the rotary encoder for the project?); maybe there is another solution instead of a rotary encoder that will do the job as well or better. It would also be helpful to know if you need an absolute or relative encoder.

That said - have you looked into hall-effect encoders? Basically, you use a ferrous metal gear (made of steel usually), with say 200 teeth. You put a hall-effect sensor with a small magnet behind it (the sensor needs to be for this kind of application - check datasheet information for details), and you put this near the teeth of the gear. As the gear rotates and the teeth sweep by the sensor, the magnetic flux changes due to it coupling with the teeth as they pass by. This change is detected by the hall-effect sensor, which can be amplified and ultimately used to determine rotation speed and other parameters. Two used properly can sense direction of rotation as well.

Such a system will only give a relative reading - and can't give you an absolute position - but it is a very robust solution; such a device is used in cars all over the place, mainly as sensors for the crankshaft and camshaft of the engine, as well as to measure speed of the wheels (for ABS) and sometimes in the transmission and drivetrain (AWD).

Yeah, you'd need to come up with some maximum dimensions for us to help you. I'm guessing for the picture it will be one with a shaft. What kind of shaft? Which diameter? Also, it would be helpful to know the application. What kind of wear and tear are we expecting?