Single input (Voltage) reading

Using Arduino Project Guidance
#1

Hello,

I'm new to this. I have a project where I a looking to read the voltage reported off a lock in amplifier and then get it to read as a digital item on my computer screen. I have a lock in amplifier. I will have one wire providing the demodulated information from the lock-in amplifier to the Arduino Uno.

During the course of time, the voltage will vary and I will need to be able to see, document and plot the variations. It seems like this is perfect for serial monitor and serial plotter. However, I'm not exactly certain how to make this work. I've been looking at projects using these tools, but they seem a bit complicated where as I suspect mine is very simple (perhaps wishful thinking). Where is the best place where I can find the basic information I need without too much extraneous information?

Any assistance is greatly appreciated.

Rene Steinhauer

#2

What are You talking about? "Lock amplifier"? Never heard of such aq thing during 45 years of eletrotechnical work? Time for updating me.
Get a 0 to 5 volt signal out of what ever device it is and feed it to an Arduino. Then, as You say, You can use Serial Monitor or Serial plotter.

#3

This tutorial may be of interest.

#4

AVR chip Arduinos have a 1.1V reference for analog read. With a voltage divider you can get your input to 1.1V or less.

By default the analog reference is VCC which can vary.

#5

groundFungus:
This tutorial may be of interest.

That's what I needed. As for what a Lock-in amplifier is, it is used for science experiments. I'm working on one now and need an inexpensive way to look for very small changes in electrical output.

Rene Steinhauer

#6

very small changes

Can you quantify “small changes”. The basic Arduinos have 10 bit converters. That means, even with the 1.1V reference, at best 1mV/bit resolution.

#7

GoForSmoke:
AVR chip Arduinos have a 1.1V reference for analog read. With a voltage divider you can get your input to 1.1V or less.

By default the analog reference is VCC which can vary.

Thanks for the info. Do you know to how many digits it can read?

#8

To be more clear, my understanding of my lock-in amplifier is that it will send a "report" of the voltage in nano-volts to my arduino. For example. 1.000000024, 1.000000025,

So I need to be able to read these input from the amplifier on the arduino. Does that help out?

Rene Steinhauer

#9

Arduinos uses 10 bit converters. That gives readings of 0.000, 0.001, 0.002 up to 1.023 volt.

#10

need an inexpensive way to look for very small changes in electrical output.

I doubt that you will find an inexpensive way to measure nano Volt changes. You certainly will not measure nano Volts with an Arduino ADC.

#11

A link to the actual device certainly will help you explanation. The more I read, the more I think your device is sending the value read using a serial data communication. Is this correct?

Paul

#12

medicrene:
I will have one wire providing the demodulated information from the lock-in amplifier to the Arduino Uno.

Only one wire? Is it an antenna? Please post a system diagram.

#13
#14

Interesting, What kind/version of lock amplifier is OP using?

#15

medicrene:
To be more clear, my understanding of my lock-in amplifier is that it will send a "report" of the voltage in nano-volts to my arduino. For example. 1.000000024, 1.000000025,

So I need to be able to read these input from the amplifier on the arduino. Does that help out?

Rene Steinhauer

Oh no, forget that. AVR ADC gives 0 to 1023 plus absolute error may be +/-2 steps.

#16

Railroader:
Arduinos uses 10 bit converters. That gives readings of 0.000, 0.001, 0.002 up to 1.023 volt.

My understanding of the lock in amp is that it will provide the voltage info. i need the Arduino to read the number and print it out. As such, the shortcoming you mention should not be an issue. Am I missing something?

#17

Tell how that comunication looks like. Is is some kind of serial protocol?

#18

Please post a data sheet or manual or schematic for YOUR lock in amplifier. We are wasting time until we know, precisely, the communication method.

#19

Paul_KD7HB:
A link to the actual device certainly will help you explanation. The more I read, the more I think your device is sending the value read using a serial data communication. Is this correct?

Paul

Yes, this is correct. The lock in amplifer can be found on amazon at:

The device is inexpensive, but it comes without any documentation or assistance. I've seen details of it being used, but nothing that helps me figure it out well. I hope to start working with it this week. I think I have a good understanding of what I need to do, but I still don't know how to get the Arduino to "read" the data.

Rene Steinhauer

#20

It looks like a manual exist. I qutoe what I found:

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Question: 
Is there a manual for this product? 
Answer: 
Yes, you can ask for the manual via the Amazon email, and we will send the pdf version to you. 

Shenzhen Taida Century Techno…
Seller · January 6, 2020

You can proceed and hopefully find out.