Recording weak electrical signals using Arduino and amplifier

I am seeking to record weak electrical signals (up to 150mV with 0.1mV step) with Arduino. I think I have to use an LM358 op amp with 48k and 1k resistors but am not sure this will work. Can someone help?

These signals also come from different sources, do you think I can use one breadboard to record all datasets?

Also, if anyone knows what kind of test probes will be appropriate for these signals and about necessary components for this circuit that would be great.

Any help is appreciated!!!

I would use the ADS1115 external 16 bit ADC module. No op amp needed.

Thank you! I'm reading about this now. I could read voltage from 4 different sources with just one of these if I've understood correctly? Have you used it?

Yes, I use that ADC. For your purposes you can use the 256 mV range.

Beware that the voltages on the input pins must be between 0V (GND) and the ADC power supply voltage, or it will be instantly destroyed. Many people are confused by the differential inputs and think that negative input voltages are allowed, but they are not.

Ok. Thanks.
What kind probe do you use to connect the ADC to Arduino's I2C. I'm a bit lost as to the circuit's components.

I solder header pins to the ADC module, to an Arduino (e.g. Pro Mini) and use four jumpers to 5V, GND, SDA and SCL, like these ones:

This video tutorial is OK, despite the typo in the title.

Without knowing what you're probing? Kind of hard to answer that one.

my bad. I am measuring electrical impulses from trees (for context this article's abstract is helpful Evaluation of electrical signals in pine trees in a mediterranean forest ecosystem). Electrodes should be stainless steel screws.

How widely separated are the electrodes? Oh, never mind, the paper you linked to beats the subject to a pulp. How could you possibly need to know more?

this is great, thanks.
Would you know about the power supply the ADC module needs? I am planning on using an external 360W power supply and would use its ground electrode for the ADC and Arduino as well.
For context, the power supply is powering LEDs and Arduino.

The 5V output of the Arduino can be used to power the ADS1115.

But it is a really bad idea to mix high current devices like 360W power supplies and LED lighting with measurements of very low voltages.

When measuring sub-mV signals, you cannot have your wiring exposed to electrical noise of any sort (e.g. room lights and appliances) or you will get overwhelming electrical interference.

The ADS1115 and associated circuitry will need to be in a grounded metal box.

I can tell you confidently that it uses a tiny, tiny fraction of 360W. Also Adafruit documentation is very good. Have you read it?

May I suggest this before you go running off in different directions?
Get one of the small hand held digital oscilloscopes that can be operated for several hours by a 9 volt battery. Examine all the test points you are wanting to record with that scope and SEE what signals are available and what they look like. You will also be able to determine the NOISE signals your project will also be recording.
My portable scope was quite cheap and I use it in the house while the big TEK scope remains out in the shop.

Theoretically you could get close... The regular Arduino has a 10-bit ADC (0-1023) so with 150mV maximum, each step is about 0.15mV.

In the real world noise is often a problem with millivolt signals so it's usually the noise that limits true resolution.

Yes. I'm using an external power supply for the LEDs anyways so I was wondering if I could also use it for Arduino and amplifier but @jremington is right that I can use Arduino's 5V output for the amplifier rather than mixing high current devices with low voltage measurements.

Is this the same as this thread?

Tom.... :smiley: :+1: :coffee: :australia:

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Yes its the same project!

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