Needed Items:
– Cheap 3.3v Buck Regulator (CANNOT BE LINEAR/LDO)
– Some small AWG Wire
– Proper hot air gun (hair dryer will not work)
– Hot glue to secure the regulator (or any other thick glue)
– Soldering Iron & solder
– Patience 🙂
I started by cracking open the radio, it’s pretty straightforward so I’m not going to explain it. All of the screws are the same and all of which use phillips. You may need a slightly longer screwdriver to get to the side screws. There are screws under the grips and batteries.
Once inside you will find the mainboard PCB, this needs to come off too. Same phillips screws and a bunch of JST plugs to undo. Ribbon cable can be disconnected by folding the black part of the plug upwards, all of the JST plugs are friction fit. You will then see the ELRS module as below:
Take the module out by removing the 2 hex screws and carefully twist the UFL to break the liquid electrical tape, then pull up gently on the plug. You will then need to remove this voltage regulator with a hot air gun, it’s pretty easy but you have to be aware of when the solder liquifies. If you wait too long after solder’s liquid you will start melting components. I put mine on max temp (480C) and blasted it for around 2 minutes until I noticed the solder start to look a bit shinier and that I could easily push the components around. I then pulled the regulator off with tweezers:
I then prepared the Amazon buck regulator module by bridging the 3.3v pads with my soldering iron and cutting the ADJ pad, you can see the scuff marks. If this pad isn’t cut the module won’t output a full 3.3v. Connect this to a battery first and measure if it’s outputting 3.3v with a multimeter or you risk frying it / taking it all apart again.
Heatshrink your regulator and connect it to the board with your wires as follows:
I stuck my regulator here in the radio with some hot glue, nothing super special. I don’t think there’s a better place to put it:
Now just re-assemble the radio, you’re done. 🙂
Best of luck to you!
What is the current draw before and after? Battery life?
My unscientific testing is showing 320mA draw @ 8v at 250mW on ELRS. I would love some more data points though 🙂
How does this current draw compare to the original?
Thanks for the instructions. Just made the same conversion using a D-SUN adjustable 3A regulator. Hopefully will give me a bit more stick time out of a charge.