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This project began as a reproduction of a remote focus motor published on the internet by Brian Sumpter(thank you!)  (here).  A 'gutted' servo controlled by a DPDT switch to reverse polarity (and hence direction) with a potentiometer to adjust the speed.  That was quickly followed by modifications like a PWM supply and an H-bridge for better speed control in both directions. This worked great but lacked 2 important desires....

    1) an interface that matches the movement of a focus knob

    2) autofocus

Both of these have been achieved (see Pictures and Videos page) in a very easy to build, inexpensive design, by utilizing a Pololu Maestro 6 channel servo control board coupled to a stepper motor via an H-bridge.  Movement is accomplished by turning a rotary encoder.  Autofocus by 'homebrew' C# code.  The mount, made from aluminum stock purchased at a local hardware store, is attached via the finder scope bracket.

The lastest version now uses and Arduino Uno control board, a pololu A4983 stepper driver and a much larger 6volt stepper motor.  It still functions as a stand-alone unit for visual use, and can be controlled via a modified version of the home built C# autofocus code. 

The software has been significantly updated to utilize a method that eliminates the need for backlash compenstation(adapted from the FocusMax paper here)

Note the flexible motor shaft coupling in the picture....

*******  If you just want to try it out with your Arduino setup  *****

I have also added a bare bones version of the Arduino focuser (here: Arduino Focuser 2) that does not use a keypad, LDC or rotary encoder and will work with any ASCOM compliment software.  

Also check out Sound Alert a simple program that sends an email when your computer makes an alert sound.  Designed to be used with PHD and send a text message via email for lost guide star. 

Inside the Box....

Original version with manual focus via rotary encoder, keypad, LCD display and dual stepper drivers for Orion filterwheel modification.