Raj made a temperature and relative humidity meter to demonstrate adaptive brightness control on a seven segment LCD. The system uses a LDR light sensor in a closed loop to continuously adjust the brightness of the LEDs.
The objective of this project is to illustrate a technique of implementing adaptive brightness control to seven segment LED displays. It consists of a closed loop system that continuously assesses ambient light condition using an inexpensive light-dependent resistor (LDR) and uses that information to adjust the brightness of the display. For the proof of concept, the technique is applied to construct a digital temperature and relative humidity meter that adapts the brightness of the seven segment LED displays to the surrounding lighting conditions.