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 https://github.com/hibikiledo/AM2320
LCD display i2c library https://github.com/fdebrabander/Arduino-LiquidCrystal-I2C-library


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

How to build high current hall effect sensor

I published hall effect sensor circuit diagram and my audience asked me how to make a hall effect sensor that has a high current capability, so I made it for him and for all of you who want to build high current hall effect sensor.


Normally, hall effect sensor used for detect magnetic field and send output to a microcontroller, that means any hall effect sensor doesn't need to have high current output. However, if you want to drive motor or any high current device without a microcontroller, this circuit is the best for you.

List of components for this project:

1 x IRF 9540N (P channel MOSFET)
1 x A3144 hall effect sensor
1 x 1 kilo-ohms resistor
1 x 10 kilo-ohms resistor
optional (use for led indicator)
1 x 1 kilo-ohms resistor
1 x White, red, blue or any other low current led

Note: all resistor for this circuit is 1/4 watt, 20 % tolerance is ok with this circuit.


The principle of this circuit:

When hall effect sensor detects magnetic field, it sends output low (0 volts) to P channel Mosfet.
P channel Mosfet starts to conduct current when Gate pin has lower voltage potential than Source pin.
Mosfet is a voltage control device so it is easy to drive a Mosfet with low output current sensor like hall effect sensor, light sensor.


Wiring diagram and circuit test video:




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