The first thing I had to have was a transmitter.
It had to be cheap, programmable, upgradable, cheap, modular, usable as a simulator controller, cheap and preferably compatible with my V911 helicopter. Did I mention cheap?
I know it was a lot to ask for, but the Turnigy 9X (aka FlySky TH9X, iMax 9X, etc.) met all the demands. There is also the 9XR, which is an evolution of the 9X, but didn't seem to me that it was worth it. It costs practically the same, has a bit more "bling", but comes without a transmitter module, receiver and you can't use AA batteries.
After a lot of research, I finally ordered the TX, along with a backlight kit, a simulator cable, a USBASP adapter and some female mini-USB connectors.
Once I received all the ingredients, it was time to start cooking!
The Simulator/Trainer Mod
When I first tried to use the 9X as a simulator it simply would not work. I remembered having read something about that while I did my research, so went back to Google in search of more info.
Apparently you have to unplug the RF module to enable the sim port. That would not be a problem if you could actually remove the module, but the antenna cable is attached to it. So you risk damaging the cable every time you use the simulator...
Turns out there is a simple fix for this problem: you just need to add a 1 kOhm resistor.
I decided to keep it simple and just place the resistor over the track. Using an x-acto knife, I made a small cut on the track and also scrapped two bits to expose the copper where the resistor would be soldered. The cut is hidden by the resistor. It would look nicer with an SMD resistor, but this one was what I had.
At first I just plugged everything just as the instructions said. You get a nice backlight which is on whenever the TX is on. That was OK, but if I was going to upgrade the software to ER9X, I might as well use it's ability to turn on the light only when I want to.
I tried to follow the instructions I found on the web, but they all involved modifying the jumper cable included in the kit. That seemed to me a bit too complicated for something that should be fairly simple.
Turns out all I needed were the two middle pins of the connector, a BF170 transistor and a 470 Ohm resistor. Since there are test pads for those pins on the main board, I could just mount the transistor and resistor there, avoiding unnecessary wires and plugs.
The Programmer Mod
Even before ordering the TX, I had decided that the programmer would be installed inside of it. Since it costs just 5 USD and I wouldn't be needing it for anything else, it was a no-brainer.
I de-soldered the male USB port on the USBASP adapter and connected the four wires to a female mini-USB connector, mounted on a small board that would fit a slot in the battery compartment. This way I would not have to modify the outer case in any way. The board isn't even glued or screwed... just press fitted!
I was going to repeat the process with the wires that connect to the main board, but if everything was soldered I wouldn't be able to separate the front and back covers of the TX. So I decided to leave the 10 pin plug, using the cable that came with the programmer to connect to the board.
Done!
That's it for now!
I haven't included any sources because I can't remember which ones I used. But you can find a lot of information on the 9X here and here.
I guess there were a few more mods I could have done, like haptic and voice feedback for example. But since I'm not trying to break any records I'm going to stick to what I need.
I'll probably have to mod the RF module when I buy another one, removing the antenna from the TX and installing it on the RF module itself.
I'm currently waiting for a LiFe battery to replace the NiCd pack I'm using. More on that when it arrives.
Have a safe crash,
Miguel
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