I am interested in creating a Voltage monitor using an RGB LED. Currently I am using testo voltage monitors, but I need to soon test about 48 on a continuous basis, and I would like to have a quick visual indicator that the device is receiving the 6V supplied. Ideally the circuit would allow for 5.7V-6V Green, 3V-5.7V Blue, below 3V Red. Any ideas or alternate suggestions would be greatly appreciated. I do not want to use a siren due to the working conditions, just want a quick visual indicator if all 48 of the devices are receiving the 6V supply.