adding a slow motion controller

I am relatively new to astronomy and have purchased a used, older Meade Starfinder EQ mount for my 6" reflector. It has an R.A. clock drive and a previous owner added a custom slow-motion manual hand controller for the declination axis. I would like to add some type of controller to correct the R.A. axis, either manual or electronic but am not sure what kind of equipment is available to do this. In my limited experience, I have only seen a manual hand controller on a celestron mount which worked in a logical manner (you turn a lead screw interlocked with a gear that encircles the axis) and I could see how similar device could be installed on my mount although I'm not sure what to be asking for. Alternately, it seems some type of electronic device that affects current flowing to the drive could achieve the same effect, but again I don't know what what such a device is specifically called, nor do I know which kind (for all I know there are different ones for every type of drive out there!) is appropriate for my mount. If anyone can give me some insight into this I would appreciate it. Thanks! Adam Schoonmaker, Westford, NY

Adam, the RA drive you have is most likely driven by an ac synchronous motor. They are good motors but unfortunately the telescope industry has made several iterations since that drive was new. Now stepper motors and even newer, servo motors, are most commonly used. They both run on DC voltage. Changing your motor over to one of these is possible but I wouldn't recommend it unless as a last resort.
There used to be commonly available drive correctors that would change 12dc into 110vac with a variable frequency output. The variable frequency would allow minute changes in the speed of the ra motor to make corrections for drive errors when doing astrophotography. However, no synchronous motor can be sped up enough to allow a goto type operation. That is why most have gone to servo motors because the speed range available is very great.
First you have to ask yourself why you want to have the variable speed capability. If for photography purposes, Astromart frequently has older drive correctors like I mentioned available. As a matter of fact, one was just listed a few days ago and may still be available. As for the declination axis, if there is a manual slow motion system there you can simply add a 12vdc slow speed motor, maybe 1 rpm, to that and the controller mentioned usually has an output for the dec axis that allows you to run that type motor.
Once you get a system like that going you would be good for some piggyback wide field type astrophotography, which is a great place to start. Once you master that, you are well on your way to wanting bigger and better, which is where we all end up sooner or later!
Welcome to the world of amateur astronomy!

Walt