Make/Mod your own RC Transmitter

by roxes1 | May 17, 2014 | (7) Posted in Projects

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:

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!




laalex29 on June 11, 2014
make video please :)
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roxes1 on June 11, 2014
My schedule has opened up so I guess I could try. Would an instructional (run down of how I did it) or functional (show that it actually works) video be better? Or maybe both?
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Yogenh on June 13, 2014
I think both would be great if you could.
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RaptorTech on June 11, 2014
Nice! That's quite the hack. With the Nano and FRSky module, wouldn't it have been cheaper just to buy a simple 6 channel radio?
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roxes1 on June 12, 2014
yeah it would have been cheaper (~25-30) but I've come to find the FrSky system is very reliable and the ability for throttle cut and dual rates make an interesting experience. Plus 8ch why not? The oddest things require more channels in this hobby like gps and leds. Otherwise I'd have an old radio lying around the bench and as of now it may become my main remote for a while ;)
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Kurt0326 on June 12, 2014
I would agree the ACCST system is very solid.
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Kurt0326 on June 12, 2014
maybe, but not as fun! ;)
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squishy on June 15, 2014
The TX you used still has some of the worse gimbals in the business. At least start with a decent radio so the final product is at least a decent radio..
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roxes1 on June 16, 2014
I agree that these gimbals are not very good (maybe I'll mod a better one later), but this is more of an experiment plus at a certain point I'd end up with just buying a 9x radio or similar than go through all the trouble.
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chils41 on June 13, 2014
great work man, I have been searching for suck code for long time.
have some OLD FUTABAs lying around, must make a good use of it.

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Gravitysucks on June 12, 2014
He did it because it was possible :). Nice.

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kms64 on June 12, 2014
Sir, I salute you! Unfortunately, some of us (i.e. me) don't have the skills to do this kind of work but I sure do think it's cool! Video would be nice.
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Make/Mod your own RC Transmitter