Since DJI released its Digital FPV System, many of my quads were converted to fully digital, but several were not. I didn't like the idea of carrying 2 goggles with me when I went flying and started looking for a solution.
The DJI FPV goggles do not accept an analog module, but they do have an analog video input. I considered the Furious FPV Dock King, but at $90 and only the ability to use a True-D module, I decided it wouldn't work for me.
In the age of 3d printers and the internet, I figured it would be easy to create my own module dock.
After a quick search on Thingiverse i found this:
Problem solved, a DIY module dock I could 3d print and build for cheap!
This design allows any FatShark compatible module to be plugged in and provides a solution for 3s to 6s battery input and video/audio output. What's more, it is designed to have the ability to add channel selection buttons and to be mounted to a tripod.
The STL files provided by the creator include a FatShark style top plate that allows module covers that fit a FatShark goggle to be installed protecting the module, a center plate for mounting all the electronics, and a bottom plate.
Another quick search on Thingiverse and I found a printable face/cover for the Rapidfire that I could print in the same colors I intend to use for the dock.
As for the electronics, the creator of the 3D files also provides some links to everything needed, but I wanted them as fast as possible so I turned to the Devil, Amazon.
Amazon Part Links:
Pololu 5v Step-Down Regulator
PCB Headers
2.1mm Barrel Connector
Note: This connector is actually too long to fit inside the dock and I need to heavily modify it to fit properly. I recommend looking for something more compact.
3.5mm Video Connector
3.5mm Video Cable
M3 Button Head Screw Kit
1/4" nut for tripod mount (I found one laying around, they are pretty common)
You will also need 2 smaller screws for mounting the Voltage regulator which I found laying around.
Now that I had everything I needed, I started printing the files.
After I had the prints, screwed the pieces together without electronics and sanded everything to clean up the prints. Then I applied several layers of clear coat to attempt to create a finished look. You could easily skip this step and I would if doing this again because it didn't help that much. I most likely need a better printer.
The Module Dock creator was kind enough to supply a wiring diagram to help with soldering. After verifying the wiring was correct on forums, I started putting it all together.
I did not add buttons as the joystick on the Rapidfire gave me all the control I needed and I did not solder up the audio because I don't use it.
Using a multi-meter I found which pads were for video/ground on the video connector and power/ground on the barrel plug.
With the wiring finished and verified to be correct, I screwed everything together.
For the tripod mount, there is a slot in the center print for holding a 1/4" nut in place. I found a nut laying around that worked and held it in place with a bit of hot glue. BE CAREFUL using hot glue as it can melt and deform the PLA.
Tested and verified to allow me to receive an analog video signal to my DJI Goggles. Please note, it will work with anything with 3.5mm video input.
If you use any of these 3D files, please support the designers with a donation. It takes time for these designers to create these and their time isn't free. Thank you.