SparkFun Forums

[powpow57]

Hi I stumbled onto this site because I was searching for an signal amplifier for a S type load cell. I'm wanting to install this load cell on my engine dyno. The signal that comes out of the load cell is mv and too small for the data computer to see as far as I can tell from what I have read. I placed your signal amp on order then found that you have a temp / humidity sensor that would work for my weather station. I see that sensor needs the artemis redboard to function. I dont' know how this stuff works but I'm very good a figuring stuff out. Question. What powers the red board? Do you just plug in the usb cable to a computer or charging plug? Software to run the redboard? Is something else required to make the redboard function? What about the amplifier? Does that require a power source or would that get power from the redboard?
Currently I have a map sensor and an air temp sensor that feed a 0-5v signal to the data computer for barometric pressure and temp. I have to input the humidity manually as I don't have a sensor and was hoping this would work. Any advice on which components I would need would be much appreciated

[liquid.soulder]

Hi powpow

Can you share a link to the signal amp that you ordered? I don't know enough to tell you if it needs a power source or what without knowing which one it is.

You are right, usually the products that we sell are meant to be used with a microcontroller of some sort. It does not have to be the RedBoard Artemis (which is just one of our many microcontroller boards). In fact since you are just getting into what sounds like your first project I would recommend another board such as the regular RedBoard (this one has a Qwiic connector to make sensor attachment super easy)which is a good starter board because it is compatible with many many Arduino Uno shields or the more powerful (but still easy to use) ESP32 Thing Plus. The main reason I am dissuading you from using the Artemis is because we are still developing software support for it - most things work but there is the potential of finding a bug. An experienced microcontroller user would be able to spot it as an issue but I wouldn't want you spinning your wheels for too long on something like that.

The code examples that come with the temp/humidity sensor will work on any of the boards I mentioned when you use the Arduino IDE.

The RedBoard can either be powered through the USB cable or from a battery pack going through the barrel jack (Here's an example of the sort of plug you might use to connect) The schematics of a board (like this one for the RedBoard Qwiic) will tell you the acceptable voltage range (the RedBaord Qwiic can take 7V to 15V on the barrel jack - USB should always be 5V)

As far as software goes you will program the microcontroller board using the Arduino IDE (which you can download for free). It is as easy as downloading the IDE, adding the right package to support your board, and then trying the example code that comes with the sensors. Then you can start building your own application out of all the examples for your various sensors etc.

I'm not sure about how exactly you can get these measurements into your data computer without knowing more about it. Can you share the model or some more information?

Hope that is a helpful start -don't hesitate if you have any other questions!

[powpow57]

Thanks for the reply. I found a humidity sensor that puts out a 0-5v signal that I can send to my dac from another supplier so I'll go with that. So now I'm just looking at the scale amplifier
https://www.sparkfun.com/products/15242 . Does this device require the redboard to power it and does it put out a 0-5v analogue signal that I can send to my data acquisition computer

[liquid.soulder]

Ahh, I see. Yes, that board will require a microcontroller board such as the RedBoard to operate. It is possible to power it from any 2.7V to 5.5V power source but it does not appear to have an analog output. The only ouput uses I2C which is a digital protocol that requires a master device to ask the sensor for readings.

One way you could make it work is by reading the sensor using I2C from a RedBoard and then using a Digital to Analog converter to supply a corresponding analog signal to your data computer. Here is a DAC that you could use: https://www.sparkfun.com/products/12918

You may be able to simply connect both the load cell amplifier and the DAC on the same I2C bus all powered right off of the RedBoard Qwiic (I2C) bus. If you do that then the DAC might have a maximum voltage of 3.3V. You could also power the DAC at 5V to be sure that the full scale reading is 5V but then you might need to use a level shifter to talk to the DAC (or maybe not - sometimes these things will work anyway)

No matter what it could all be powered by the power supply on the RedBoard so you all you would need is the USB to power the RedBoard (or a dedicated power supply at either 5V exactly (easy) or 7V-15V (which you would need to route through the barrel jack so that it could be regulated).

If you can find an analog load cell amplifier that would probably be an easier solution for you. I think anything like that (active amplification) will need to be powered from your data computer.