Guitar tops tend to split and crack under certain temperature and humidity conditions. This hygrometer tracks the amount of humidity in the guitar case to make it easy to keep the humidity and temperature in check.The device uses a DHT-11 temperature sensor to monitor humidity, an ATMEGA 328P as the microcontroller brain, a CR 2032 as a power source, and an NTE LED bar graph to display the amount of humidity in the case. The code for the project was written in the Arduino IDE and burned to the MCU by using an Arduino UNO as a programmer. The code uses a DHT-11 specific arduino library to simplify the process down to single lines of code. That library can be found here:

My Code:

#import "DHT.h"
#define dht_apin A0
//DHT.humidity is the correct command to pull humidity from DHT11

dht DHT;

void setup() {
    pinMode(0, OUTPUT);
    pinMode(1, OUTPUT);
    pinMode(2, OUTPUT);
    pinMode(3, OUTPUT);
    pinMode(4, OUTPUT);
    pinMode(5, OUTPUT);
    pinMode(6, OUTPUT);
    pinMode(7, OUTPUT);
    pinMode(8, OUTPUT);
    pinMode(9, OUTPUT);

void loop() {
    if((DHT.humidity >= 0) && (DHT.humidity <= 10))
      digitalWrite(0, HIGH);
      digitalWrite(1, LOW);
      digitalWrite(2, LOW);
      digitalWrite(3, LOW);
      digitalWrite(4, LOW);
      digitalWrite(5, LOW);
      digitalWrite(6, LOW);
      digitalWrite(7, LOW);
      digitalWrite(8, LOW);
      digitalWrite(9, LOW);
// Code is not completed at the moment, each LED will have an if statement for its condition when finished.

Thanks to user Andrew Bolin for pointing out that the project has other applications such as when storing camera gear. Camera gear can grow fungus and be damaged when stored in high humidity climates. If I have time I will re-write some code to give the project a range of humidity detection that would suit it for use with camera gear.