Humidity sensor with led alarm | Arduino project

This page contains Arduino Humidity sensor with led alarm source code. This project is good for someone who wants to make a humidity meter or hygrometer with led alarm if humidity and temperature over a threshold. It's easy to make and doesn't require an external power supply, just use power from an Arduino UNO R3 board (USB power compatible with this project).

Electronic components list:
1 x Arduino Uno R3
1x 20 x4 I2C LCD display
1 x AM 2320 humidity/temp sensor
1 x 5 mm led ( 2 x if you plan to use led for pin 13 instead built-in led)
1 x 1000 ohms resistor ( 2 x if you plan to use led for pin 13 instead built-in led)
Any USB power adapter, 500 mA current at least.

Here is the Arduino code:
AM 2320 library
LCD display i2c library

#include <Wire.h>
#include <AM2320.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x3F, 20, 4);
AM2320 th;
int led2 = 12;

simple bass booster circuit diagram

This bass boost diagram is easy to build and work well, I made it because people asked me the schematic diagram of bass boost diagram on my youtube channel.

The circuit has 9 dB gain@40 Hz that mean you will get good bass performance even you play music to a small speaker.
Why this circuit doesn't look like circuits on the internet?

Almost every circuit on the internet uses R/C filter between pre-amp and power amp stage to bypass high frequency to a ground and that seems audio signal being amplified and bypass to ground. I think it wastes pre-amplifier gain, the more gain preamp stage the more distortion to the audio signal, so I use a capacitor to send more negative feedback to pre-amp negative input when the frequency higher than cut-off frequency, capacitor impedance(resistance) higher when frequency lower and that make negative feedback decrease when frequency lower.

An op-amp distortion lowers when negative feedback higher, that mean high-frequency distortion lower when you use this circuit because frequency over cut-off frequency's total harmonic distortion being suppressed around 20 DBs more than normal R/C filter.

The C5 cap can be replaced with MKP type or polystyrene film cap with 1% Precision for the best result.

List of component:
potentiometer = 10 kilo-ohms
IC1 ne5534 (you can use another opamp that pin compatible to the ic)
R1,R6 = 1 kilo-ohms
R2,R3 =10 kilo-ohms
R4,R5 = 4.7 kilo-ohms
C1,C3 = 2.2 uf 16 volts
C2,C4 = 47 uf 16 volts at least (no more than 100 uf)
C5 = 0.1 uf
C5 value can be change depend on your listening behavior
0.1uf = + 15dB(gain = 6 times)@159 Hz and + 17.84dB(gain = 7.8 times)@80 Hz and then + 19.39dB(gain = 9.33 times)@40 Hz good for very small speaker, 2 way car speaker 
0.2 uf = + 15dB(gain = 6 times)@80 Hz  good for small speaker
0.4uf = +15dB(gain = 6 times)@40 Hz   good for someone that love deep bass boost and big speaker

See testing video


  1. Sir, Can i use 'HA17741 OP-AMP? & Resistor Wattage? Can i attach this bass booster to the input of 'PAM8610 AMPLIFIER BOARD?


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