Hi, I'm moving to another country soon and my current project was put on hold.
Here is just a small tweak to a wireless charging pad I got for my galaxy S4. I hated the single red LED close to the USB port. It looked hidious so here is my mod:
Removed top cover:
When you plug the pad to the power supply, it will flash three times (last picture was taken during them flashes), the LEDs are switched OFF. When you place your phone onto the pad, LEDs go ON until you remove the phone.
Definitely looks better than just one single red LED in the corner.
Transistor used: general PNP transistor capable of 100mA or more
Resistors: 220ohm (My LEDs had 3.2V drop @ 20mA-> (5 - 3.2 - 0.5V VCE)/220 = 6mA each x9 LEDs = 50mA (roughly)
+1 resistor between transistor and controller. I used 1k, but look into the datasheet what current your transistor need to open fully. The 0.5V VCE is voltage drop on the transistor itself - depends on the transistor used. I might hear something regarding the calculations, like voltage drop on LED at lower current will be lower ... it's not that important.
Hope you like it :)