My extra 4 channel transmitter I had laying around. Original came as an extra from a bundle I bought on ebay a while back but I didn't have enough crystals to use it plus 8*AA batteries was a pain.
took out the cicuit board, glued on some of the switches, test fit 2.4ghz module, drilled hole for antenna.
on left: bind and activity light for 2.4 ghz module (fit perfectly in old crystal receptacle). on right: fw/telemetry/normal connection modes. (more on this later)
and the big reveal the fantastic FrSky radio system. I'm using the DHT module for my diy installation. Search hobbyking or the official page for more details. Basic run-down is firmware upgrades (I didn't do any) , 2 way mode and 1 way modes. (mode depends on reciever read manual)
switches from the original circuit board. (I accidentally broke one :) )
control board the has activit light and bind switch. Preped for hot glue.
close up of the module.
had to sand a bit and and drill a bit more to get the antenna to stick out enough for me to attach the parts. the plastic was thicker than I thought here.
some 2 way switches (on-off-on) I bought on the cheap
Now on to slightly complex but fairly easy to do stuff of the actual wiring.
I'm basing this project off of some code I found alone to use an arduino as a clock to generate PPM (what the module understands) for rc control.
original link: http://www.reseau.org/arduinorc/index.php?n=Main.HomePage
Thanks a lot for making this possible!!!
using an arduino nano as the 'brain' website has great information on this.
the A pins are for an analog read in from the potentiometers in our case the gimbals. The D pins are digital which mean on and off and are used from D7 to D13 as setting switches and notifications. D2 to D6 in this wiring diagram can be used as toggle switches (like turn on flaps or lights)
facing out ward for easy access to the USB port for programming purposes. I know that trnasmitters like the 9xr have a screen and buttons to allow changes to complex control but I was building a basic transmitter and didn't require stuff like that. If someone is up for the challenge they can try using a arduino mega for more advanced features.
all wired up and ready to go. plus some hot glue to prevent shorts.
It can be powered from about a recommmended 7v to 12v power supply so I wired a JST connector for lipos and other types of batteries as well as a 9v battery strap for emergencies.
UPDATE: (sorry I'm late, but I forgot to add these videos)
NOTE: I don't make tutorials very often so this may seem very confusing but the website tells you everything you need to know. Happy Hacking!