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Ohm Meter

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Alan L
(@alan-l)
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Joined: 1 year ago
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Did a search and came up empty. Would like to make a simple ohm meter with display that will allow me to take a reading, display it, take another reading and display it and so one. This would allow me to display a series of readings to compare.

Just getting started with Arduino but have done some basic projects.

Thanks!


   
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(@codeslinger)
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learnelectronics did a series of videos on this a while back.Β  The videos, in order are

I was playing with a design myself after seeing the first video so I have a good grasp of what is going on.Β  If you have any further questions, give a shout and I will see if I can help.


   
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Alan L
(@alan-l)
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@codeslinger Thank you! Time to get educated! πŸ™‚

Β 


   
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Inst-Tech
(@inst-tech)
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@alan-1, & @codeslinger,

I watched the videos, and admired the creative thinking behind @codeslingers projects.

Now, what I'm proposing may not be what your looking for, but I just bread boarded it to see if it would work as a coding exercise.. it works pretty well, but will only measure from 1 to 1 Meg ohm..as it only has 4 ranges 200,2,000, 20,000, and 200,000... the real problem is that the Arduino only has a 10 bit DAC, so that means the voltage drop across the unknown resistor is limited toΒ  about 4.88 mV (0.004883 v)so at the lower or upper end of the 0 - 1023 ADC counts it's not going to be able to read the voltage with any accuracy.. but it was a fun project to do for the coding part..good luck, and have fun..that's what it's all about. attached files for coding and schematics below.

Β 

Β kind regards,

LouisR

LouisR


   
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Alan L
(@alan-l)
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@inst-tech Thank you very much for what you did! Would be nice to go lower than 1 ohm but this is very much appreciated.

Yes I will enjoy this!

Regards - Alan


   
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Alan L
(@alan-l)
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@inst-tech Looking at your schematic where does the Display connect?Β  Sorry new to this.Β Β  Wondering if a TFT touch screen would work instead of keypad and other display?

I know its above my head right now but would like to work toward that!

This will be fun!


   
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Inst-Tech
(@inst-tech)
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@alan-1 , Ah, sorry about that...had to many versions on file and in my haste, picked the wrong one...lol

The LCD is connected to the SDA & SCL inputs on the Arduino as shown on the Attached dwg. I used a 5 v switching power supply to furnish all power required for the circuit, so that the Arduino's 5 volt was used to power the used 3 LED's in the multiplexer circuit decoder.. they are really not needed, but for testing it was a good way to verify that the program was selecting the the correct range before I had the LCD hooked up.

As a note; it's better to measure all your range resistors and use that value in the coding as I have done, much more accurate, and using the voltage reference of 4.096 V also improves the ADC count.

The ADG609 is a dual 4:1 analog switch ( Multiplexer) that works very well for this simple design as it has very low resistance. I only used 1/2 of it as I only needed 4 channels to 1.

If you have any more questions or comments, please feel free to post them.. I hope this dwg. is easier for you to follow..

have fun!

kind regards,

LouisR

Β 

LouisR


   
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Alan L
(@alan-l)
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@inst-tech Sent message!


   
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