JoeN:
kf2qd:
Other than one has parts that are a bit more durable, and encoder is and encoder. They Give pulses as you rotate them. The various sizes have more to do with mounting than with function.Boy I disagree. The first encoders I bought were mechanical ones with detents. Then I bought several optical ones that give a whole lot more resolution and no freaking detents. I love these encoders, they are the nicest thing I have as far as user interface parts. They also breadboard really well.
http://www.ebay.com/itm/370592502534
It is so choice. If you have the means, I highly recommend picking one up.
I can't agree more with that statement. My first playing with quad-encoders was with one of those cheap $5 mechanical ones. Between contact bounce and the mechanical de-tents not always matching up well with the contact transition positions, I was pretty frustrated with the whole concept of using on in any of my projects.
Then I found a web site (gold electronics) that was selling some nice surplus (new old stock) high grade optical encoders for $5 and boy what a different (I bought 4 and they sold out quickly so don't look for them there now). It's a great device to use if you can be patient and look for a good one via surplus or used on E-bay. The cheap mechanical ones are really garbage, I'm not saying that with enough tweaking of code and you can't make a mechanical one somewhat work, but I personally will never waste my time using one. I still have 3 optical encoders left.
Lefty