In my quest toward fully remote imaging, I needed a flat panel solution that would work with SGP. There is no ASCOM standard for flat panels, so the only flat panel that SGP can control at present is the Alnitak series from Optec. For my Edge 14, I would need the FlatMan XL, which is $1300. I don't mind spending good money on good equipment, but that seems excessive to me, when DIY approach would seem to be possible at a fraction of the cost. So, I decided to try a more grass-roots approach. I found a light panel that will fully illuminate the 14" scope here:
It has very even illumination and adjustable brightness. I mounted it on the wall of the observatory, and set the park position of the scope such that it points directly at the panel:
I have tested it by manually adjusting the brightness and aside from being too reflective, it works very well. During testing, I put some t-shirt material over the scope to mitigate the reflections, but that obviously is not a solution for remote flat collection. To permanently eliminate reflections, I frosted the face of the panel with some 220 grit sandpaper and a random orbit sander:
Of course, I still have the problem with controlling the panel remotely. I found some Arduino code written by one of the SGP developers here:
It takes the Alnitak flat panel command set and parses them into PWM output on one of the PWM pins on the Arduino. To make this work, I first needed to bypass the control circuitry in the flat panel (no pics of this). I simply cut the + and - wires coming from the 12V input jack leading to the circuit board in the panel, and cut the + and - output wires from the control circuit and then soldered them together. This passes full power to the LEDs, such that their brightness can be controlled by modulating the 12V input with PWM. All that was left was to build the Arduino control box. It couldn't be simpler. It consists of an Arduino Uno ($5) and a simple NPN transistor ($1) in a project box ($3):
The only thing I had to do the the Arduino code was modify it to tell in which PWM pin I was using on the Arduino. No additional Arduino libraries are needed, and it fired up perfectly the first time. The Arduino connects by USB to the observatory computer, accepts serial commands using the Alnitak command set, and then modulated the 12V input for PWM output to the flat panel. I now have 256 completely repeatable brightness settings that are software controllable. It works brilliantly. Now SGP can perform fully automated flats whenever I want it to by parking the scope, turning on the panel, collecting flats at the precisely determined correct brightness and then turning everything off.
Works great and at about 1/10 the price of the FlatMan XL, it is a great bargain.