I have the backlight installed in my 9x which is great but it does consume about 60mA to 90mA, quite a lot for nothing when our TX is mostly in the sun, building a manual switch is simple but it requires you to remember and you may not notice that the backlight is on out in the sunlight anyway.
The custom firmware such as ER9x has a software switch for the light and a timer too still there is nothing as appropriate as a sensor that switch the backlight on when dark and off when in the sun
This can be done via few components only, namely a FET, a CDS sensor and a couple of resistors, can someone guide my hand as to how to design such a system?