Electromagnetic Meter

Im completely new to arduino but want to give this a shot. My problem is I have the uno r3, and lcd screen with the driver on the back. Im sure coding will be different because of this as well as the general layout. I would like to also use a 5 position telescoping antenna attached to a wire then the arduino. Is there any way someone could help me?

what LCD display do you have, e.g. is it LCD with I2C interface
first get the LCD operational then build the EMF detector circuit using a breadboard

yes its the i2c with interface

There are several libraries available through the IDE to drive the display via I2C. The one from Bill Perry is popular.

connect up the LCD, download the library and run an example program to check it works
the I2C address can vary - if so use the I2C scanner to find it
then implement the EMF detector

For an I2C LCD display to work, the I2C address and the I2C backpack to LCD pin mapping must be correct. If the library default settings for either or both are not correct the LCD will not work. You can try to figure out the right pin mapping and use an I2C scanner to find the address, but if you install and use the hd44780 library that is done automatically by the library.

Install the hd44780 library. The hd44780 library is the best available for I2C LCDs. The library is available in the Library Manager. Go to Library Manager (in the IDE menus, Sketch, Include Libraries, Manage Libraries) and in the Topics dropdown choose Display and in the Filter your search box enter hd44780. Select and install the hd44780 library by Bill Perry.

The class that you want to use is the hd44780_I2Cexp class. There are examples to show how to use the library. The nice thing about the hd44780 library is that it will autodetect the I2C address and the I2C backpack to LCD pin mapping.

In the examples, there is a diagnostic sketch that will help us to help you if you still have trouble with the display. Run the diagnostic sketch and post the results.

The changes to the code in the page that you linked should only entail replacing the included libraries and the LCD constructor. Refer to the examples to see what to change. If you have trouble with that part we can surely help you to fix it.

Interesting project you linked to. Notice the picture shows a wire loop to sense the electromagnetic field. But the Fritzing connection diagram shows a voltage probe for an antenna. That will detect the electric field, not the electromagnetic field. They are not the same.

The first uses a single turn transformer to sense the magnetic field. The second uses capacitance to sense the voltage.


im either going to pay someone to do a tutorial with a completed code or just get the nano and make the exact one. this is all a bit much

The whole thing is a fancy "field strength meter", which measures the relative strength of the electric field. The clue was the statement that it will indicate the power to the wall switch even with the switch off. With no current, there is no magnetic field, but there is the electric field.

Google for field strength meter for more info.

Good luck.


Well im still going to give this a go. I bought the nano and 3 position switch. I followed the wiring diagram but ran my i2c module to cut down on the wires. I ran vcc to 5v, sda to a4, gnd to gnd, scl to a5. The rest i kept the same. Now I just need to revise the code which is the part that gets tricky for me. I ran the sketch code my lcd is 027

here is what I have. The screen is a bunch of blocks in two rows. I connected gnd to gnd, vcc to 5v, sda to a4 on the nano and scl to a5
#include <LiquidCrystal_I2C.h>

Looks similar to a $2.00 volt stick.

Read the how get the most out of this forum sticky to see how to properly post code. Remove useless white space and format the code with the IDE autoformat tool (crtl-t or Tools, Auto Format) before posting code.

Do you know the pin mapping from the I2C backpack to the LCD is right. It must be the same as the library default. As you are using an older version of a LiquidCrystal_I2C library it may not be. You may want to reread reply #5.

im getting this now?

Arduino: 1.8.12 (Windows 10), Board: "Arduino Nano, ATmega328P"
unable to create a folder to save the sketch: mkdir sketch: Access is denied.
Error compiling for board Arduino Nano.
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.