Smart controller for UV disinfection light.

• ESP8266 x 1. The "brain".
• RFP30N06LE x 1. Turn on/off the UV led.
• 2n7000 x 1. Logic shifter. Distance sensor runs on 5V; ESP8266 GPIO is only 3.3V. This shifter converts it to 5V for the sensor Trigger signal.
• 22k and 11k resistor to convert 5V echo signal to 3.3v.
• LM317 x 1. For UV Led constant current source. Credits: Lewis Loflin http://www.bristolwatch.com/ccs/LM317.htm
• 100 Ohm Potentiometer, to adjust constant current value.

See main.py for wiring. TODO: add wiring diragram.