In this quick post, we will explore the different ways of turning on and off LEDs on your quadcopter or multicopter, using your radio RC transmitter.
Why do we add LED (or LED strip) to our multicopters?
- It helps us identify pilots in FPV race
- It helps us find the crashed quadcopter easily
- A good warning for bypassers on the ground
- Importantly, it looks awesome! Especially at night
LED lights don’t use much power (almost negligible compared to what the motors use! :D ). It’s good to have the LED on, but sometimes you want to turn the LED off remotely while flying, because you are too lazy to land. How do we do that? We can use our AUX switch on RC transmitter!
There are a few solutions to this, and I found some really cool demonstrations on Youtube. However it’s not a full list so please let me know if you know other good implementations.
All these methods require you to have at least one spare channel on the radio receiver, and you are not running CPPM.
Get CleanFlight on Naze32
CleanFlight has this awesome feature that supports RGB LEDs to change colour, depending on flight modes, voltage warning, orientation, etc. Here is how I setup the LEDs with Cleanflight on my Naze32 flight controller.
And here is a quick demo.
Using receiver controlled switch (Transmitter PWM On Off Switch)
This is the simplest solution. This on off switch works straight out of the box, it is controlled by a channel of the RC transmitter radio.
Here is an example of the kind of switch. Minimum amount of DIY work and soldering. There are 3 wires come out of this switch. The signal wire goes into the spare radio receiver channel, one of the red wire connects to the positive end of the LED strip, the other one connects to the positive end of your battery (or power source).
Using Old Servo Board PCB
Apart from a ready made receiver controlled switch, you can also hack a old servo, and turn it into something useful.
All you really need is the PCB from the servo, plus the pot. But you can replace the pot with a couple of resistors. It takes a PWM signal from the receiver, and the PCB will adjust the voltage at the output.
Set the output arm/pot at neutral and they will turn on when you put the switch one way.
Only problem might be the voltage you are allowed to apply on it, and the maximum current that is allowed to pass. Most 9g servo can only handle 5v and run a current around 200mah.
To tackle that, you can consider driving a transistor switch circuit for higher voltage and current (e.g. 12v).
With the Servo PCB you can even create a diming effect on the LEDs.
Here is a good tutorial on how to make on step by step.
Alternatively you can use an ESC to replace the on-off swtich. But it has to be a brushed ESC, not a brushless ESC (which is 3-phase). It’s not a lot cheaper nor easier than the receiver controlled switch, but if you have one available you can try it.
This might seem to be a bit overkilled, but if you are a DIY geek, it could be a fun challenging project. There are many affordable microcontroller you can use, such as the PICAXE, Arduino.
For example the PICAXE can be used to switch LED lights on and off, and even to generate the flashes or different lighting patterns. The PICAXE chip can be programmed direct from a PC using free software, and is programmed in BASIC. It runs off up to 5v, but with the addition of transistors in the output stage, can be configured to switch practically any voltage and amps.