If you have a spare channel on your radiosystem and want to use it as on/off switch for lights but you dont have a module for it, then you can us a old servo instead.
All you have to do is to take it apart and disconnect the motor.
On the + and - connection you put on the lights. (I have used a LED for the test)
The small potentiometer has to be set in the middle. (off).
Test untill you sure it works. When you are sure it works then you have to glue the potentiometer so it stay in place.
Thats it... you now have a on/off switch. :-)
Please ask for questions...