Hi Stuart,
I don't offer kits, but all of the hardware designs, schematics, and parts list can be found here:
http://www.astroeq.co.uk/tutorials.php?link=/doku/doku.php?id=buildownYou can use higher power stepper motor drivers, you just need to find ones which have a "step", "direction" and "enable" interface which seems quite common, and also make sure it has the ability to set the microstepping mode via selection pins. You can also use higher voltage drivers if you want, but if you are going to do that, use a different 5V regulator for the rest of the controller (or even have an external 5V supply, only needs to be ~50mA).
In terms of microstepping, 32 is the maximum supported but I could change that in the config utility. One thing to be aware of is that there is a limit to the resolution you can achieve with AstroEQ - typically ~0.5arcsec/ustep. Using a higher microstepping mode like 64 may push you past that at which point the config utility will start indicating errors that the ratios are not possible. If you let me know what gear ratios you are planning on using and motor step angles I can have a look to see if 64 is possible.
The synta handset is untested. Theoretically if you add a port to connect it and logic level translation to ensure the signals are 5V TTL levels, it should be possible to connect the handset up as AstroEQ uses the same protocol. There are resistors in line with the TX/RX lines of USB-Serial IC in the schematic (The PIC IC could be replaced with an FTDI or other USB to serial circuit if you choose), you would connect the handset up on the ATMega side of those resistors which would mean that if a hand controller was plugged in it would take priority over USB. But again, this is not tested as I don't have one!
The protocol doesn't support position sensors and all of the positioning is done in software in the AstroEQ firmware. Unless you could ensure that your positioning system had the same resolution as one microstep it would be very difficult to rewrite the AstroEQ firmware to suit external encoders. So basically I have no plans to support external positioning.
If you have other questions or want to know if a specific motor driver will work etc. feel free to ask.
Regards,
Tom.
In terms of microsteps,