[simpits-tech] Panel lights dimmer

[terry at coslink.net]

Hello everbody...its been years since I've posted to the group but I always follow the posts 
everyday.

I am trying to add LED back lights to my panels and wish to have a dimming circuit.  I would like 
put 3 in series per leg and use +12v to power them.  I use PWM and some microchip logic to control 
and dim LEDs used on my landing gear panel but that is only 5 LEDs, each individually controlled 
directly by the chip.
 
Now the problem,  I would still like to to use PWM to dim the LEDs but every schematic I can find 
connects the B+ to the LEDs and uses a FET circuit between the LEDs and ground.  This would require 
2 extra wires to each panel. (+12v, -LED control)  Because all of my panels already have a ground 
wire I would like to place the circuit between the 12v supply and the LEDs.  That way only one 
extra wire needs to be run (+LED control), with the bottom of the LED circuit going to the common 
ground.
 
Does anyone have a schematic of such a circuit?  One that starts with logic level signals and 
floats the control to the +12V supply side.
 
Thanks in advance for your help.      
 
TerryM