I've began working with using Micro Controllers from Parallax, and learned a few things so far. Now I would like to get a rotary servo (DC motor with rotary encoder, no the PWM thing) to play around with in some development. How-ever I'm having a hard time locating one for a decent price. I'm not looking at using a HUGE servo (like the one LL was selling), but some small 5V or so thing to test with. I really dont care the power, or the amount of steps per rev. Anyone know of a place, or might have one willing to sell? All I could find is industrial "packages" that are nearly $800 a motor, and $1500 for a controller. I'm just looking for a $20 jobber to test. I was alomost considering pulling apart an old mouse, and mating on of those encoders to a DC motor, but I was unsure the speed at which a mouse encoder could read.

With in time, I will want to get something like what LL had, but thats down the road.



MyYz400

You're just looking for something to experiment with right?

I haven't had a whole lot of luck with servos myself, and I'm not very versed in servo terminology, so it's possible this isn't the kind of "servo" you're looking for.

There are a bunch of people selling servo motors for RC vehicles on eBay. A quick search makes it look like you could buy one for around $25 (already greater than how much you're looking to spend). Before you buy one, make sure you find out what it takes to drive one of these 'lil servos.

I guess you can use an Arduino to control this kind of servo, here's a cool site that has a few well made videos about Arduinos...
Guide to Arduino's[sic] & Shields
Arduino! Servo motor control
This guy is also a CNC enthusiast (hence the URL: NYCCNC.com) so you may find the rest of the site interesting as well.

If you'd like to buy a servo that can actually do some work you can check out Keling, they sell steppers, servos, Gecko drivers, their own drivers, and a whole bunch of other stuff. I've ordered stuff from them a few times. Their prices are low and the quality is acceptable (IMO).
There's also HomeShopCNC. I haven't ordered from them yet, I don't think. They seem to have very similar looking motors to Keling and I wouldn't be surprised if they both use the same motor supplier. The servos that they sell have the encoders installed already. I'd say the convenience of not needing to install the encoder yourself is worth the small premium they charge.
I haven't looked at the servo driver prices lately, but it looks like you might be able to get away with spending about $220 (a mere 11x your target price!) to get a powerful servo and driver.

Yeah Hirudin, the first servo's you showed are not what I'm looking for. Those have circuitry inside (plus motor and gearing) that run off of PWM. Their rotation speed (for continuous rotation servo) is set by the length of a pulse in. They are easy to control, how-ever it doesnt allow you to "know" it's position.

The second set you show IS what I'm looking for. Just a plain-ol DC motor with a rotary encoder attached. These let you know the motors exact positioning. And these are what I want to use for my future CNC project. These actually look like nice motors for that application, I just need to find something cheap to "simulate" one of these for testing purposes.