# Arduino Ohm Meter With LCD

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## Introduction: Arduino Ohm Meter With LCD

This Instructable Will show you how to make a Digital Ohm Meter using Arduino.This Ohm Meter is very Precise...and totally DIY.

## Step 1: Gather All the Material.

1) Arduino UNO (or any other Arduino)

3) 16X2 LCD Display

4) Jumper wires

5) 1X 1000 Ohm Resistor

6) A Potentiometer

## Step 2: Connect the LCD to Arduino.

2) Make the connections as under:-

* LCD RS pin to digital pin 12

* LCD Enable pin to digital pin 11

* LCD D4 pin to digital pin 5

* LCD D5 pin to digital pin 4

* LCD D6 pin to digital pin 3

* LCD D7 pin to digital pin 2

* LCD R/W pin to ground

* LCD VSS pin to ground

* LCD VCC pin to 5V

* A Potentiometer : * ends to +5V and ground * wiper to LCD VO pin (pin 3)

## Step 3: Make the Voltage Dividing Circuit (main Part)

This part is the most important part of this instructable.The Ohmmeter works on the principle of voltage dividing circuit. Which is given By: Vout = R1/R1+R2 * VinFrom here we can calculate R2 which is given by :

R2 = R1 * [1/ (Vin/Vout - 1)] Also we'll be using this formula in our Arduino Code..(See the code).

OK! So make the circuit very carefully... as shown above in the picture...

The TWO PROBES in the above picture are the two wires which we will connect to the object whose resistance we are measuring.

## Step 4: Final Step!!

After all the connections your circuit would look somewhat like the picture above.....

1) Rotate the Knob of the pot according to your ease.

2) Use the LONGEST jumper wires to make the probes.They will provide you with more mobility and ease of movement.

3) If anyone of you don't have the display , please inform me, i will post the code for Serial Monitor.

4) Connect the PROBES and Start Testing!!!!!!!!!.......

5) If you are facing any problem in this project...Please comment below....I'll be more than happy to help you.....

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Thank you and PLEASE VOTE if you liked this instructable !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

## 5 People Made This Project!

• See 1 more that made it

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## Questions

Hey,

I am a newbie to arduino, and I made your project! It is very nice! It is actually very simple without the LCD...

Can you please post the code here? I can't access the file that you are linking to. Also could you please post the code for the serial monitor? One more question, is there any way to prevent the value of the resistance from constantly fluctuating?

Thanks!

2 replies

Ritik, don't you mean decrease refresh rate? Due to the high refresh rate the guy had the value constantly fluctuating on the LCD screen. Anyways, great Instrctable! Keep up the good work :)

Shorted mine out when wife had me clean my desk off, lost the code and man trying to get the code again from where you have it stored nearly had me using language I gave up when I got out of the Army back in '77. Couldn't get it with my Maxathon, wouldn't let me in, so I used IE and it complained, and I had to kill about six windows before I could get to the right place. Don't know if someone hacked your link or my machine, but I think it may well be the link.

3 replies

I don't know why the link needs shortened.

I tried to earn some money by doing that but it turned out to be a bad idea. Now the link is not available to the people who are responsible for making the money by clicking on the link..

Hey,

I am a newbie to arduino, and I made your project! It is very nice! It is actually very simple without the LCD...

Can you please post the code here? I can't access the file that you are linking to. Also could you please post the code for the serial monitor? One more question, is there any way to prevent the value of the resistance from constantly fluctuating?

Thanks!

I'm really sorry for that and even sorry for the late reply. But the link is not working now. I wasnt aware of it, but you can definitely go for this link (https://www.mediafire.com/file/u19k4xok2d9btyd/ohmLCD.rar)

I made it! I'm wondering how to automatically convert it to kilo ohms once the resistor value reaches 1,000 ohms above. Since 1kohm = 1000 ohms. How can i put it in the codes?

How do I have to change the circuit of the voltage divider to measure not just one resistor but 6? I have resistive fabrics whose resistance change I want to measure using the Analog Read.

Sorry Caelilum,

I didn't show how to connect the "A" and "K" pins of the LCD,so that it may light up, But you can do so by joining them to Power and GND Respectively.I'll surely fix this mistake.

Thanks for the feedback!

Don't forget to put a 220 ohm resistor between 1 of the connections!

I wired this unit using recovered copper wire from old power supply transformers. Makes for easy routing and simply scrape a bit on the lacquer and you have bare wires to solder. I have used this method in several volt/amp meters, and three power supplies that I built up based on old 18650 batteries recovered from bad laptop batteries. Also built up a few electronic thermometers for our RV using the same method and Arduinos. One built on an ESP8266 that works great and can go online for the local weather when internet is available.

Oh, sorry for the poor quality of the photos, my current setup does not allow for great photos, poor lighting, and a bit shaky in my old age, plus the camera is so old, it had photos from the ark on it when I booted it up upon receipt.

Cool! You can test the resistance of all sorts of things! I tried this the cheaper and less accurate way with an LED and some probes to test things.