It looks like you are using Python 3.5. This issue you are seeing is due to the differences between the Python 2 and Python 3. The colorimeter software is not yet compatible with Python 3. So in order to run it you will need to install Python 2.7 and then reinstall the colorimeter software and its dependencies.
The light sensor used by the colorimeter is a light to frequency converter which returns the squarewave with frequency directly proportional to the light intensity. The number of samples setting (for example 500) sets the number of pulses which will used in order to measure the frequency. The period of all the pulses sampled is then averaged in order to determine the frequency (light intensity).
The software and firmware for the colorimeter can be found in our online repository here https://bitbucket.org/iorodeo/colorimeter/src The firmware for the Arduino is in the "firmware" sub-directory of the project. This will be what you want to modify to add you LCD display. Beyond that it is really up to you add the display you want and modify the firmware correctly.
It looks like the nokia 5110 is 3.3V so you may require a level shifter.
Thank you for your question. At this time we don't conduct teacher training workshops. However, we are always available to help and answer questions from individuals regarding using the colorimeter or any of our other products.
@cireyes Typically turbidity is measured by the light-scatterring properties of the solution rather than absorbance. However, we have used the colorimeter for turbidity measurements and a couple of colorimeter tests (Sulfate and Potassium) are based on turbidity.
First, you will need to make a turbidity calibration curve so that you can measure your water sample. To do this, you will need to buy a turbidity standard of known NTU (Nephelometric Turbidity Units). This turbidity standard is a solution of formazin (suspended polymer particles). You can buy these online from many different suppliers such as Hach etc. I bought a 4,000 NTU standard in 2012 from Grainger, Part # 8UVJ9.
Using this NTU standard you can prepare a calibration curve in the range that you want to measure your sample. For example, in the graph below you can see that I made a range of 0 - 4000 NTU by diluting the standard with distilled water. The Red LED on the colorimeter is used to measure absorbance.
Once you have your calibration curve, you can measure your water sample to determine turbidity !
So, the kit is just for making a small arduino-compatible colorimeter. It includes the hardware for making the device, which is a LED and sensor board, Arduino shield board and the enclosure hardware (plastic parts, screws, nuts etc.). There is open source firmware for the Arduino and software for acquiring data on your PC. Check out the documentation here: http://colorimeter.iorodeo.com.
For each aquaponics measurement you want to run with the colorimeter, you will need to supply your own reagents. We have carried out a few calibration tests for common aquaponics tests like ammonia, but I highly recommend that you make your own calibration curves with your own reagents.
This is a great question. A "Time vs. Absorbance" measurement is something we have been wanting to implement for exactly the type of kinetic assays you mentioned. On our end it is a matter of finding the time to work on this. It is very much on the list, so hopefully we will have this added sometime soon !
@Andrew The calibration step is really to get a zero or bank absorbance reference measurement. With a firmware modification it would be possible to store this value in eeprom and re-use it. We decided not to do this for a couple of reasons. The zeroing step doesn't take very long and is standard procedure. For example, different cuvettes can vary in thickness, path length, etc.
I can see how storing the zero/blank value might be useful if you are the only person using the colorimeter and can be really certain of your zero value from use to use. I don't think adding this would be too difficult if you wanted to try.
Thanks for this question !
So, we have not yet tested chlorine measurements with the colorimeter, but it should be possible. The most common method for measuring chlorine colorimetrically is with DPD (N,N Diethyl-1,4 Phenylenediamine Sulfate). DPD turns a pinkish color in the presence of chlorine, which is measured at 520 nm.
The Free Chlorine DPD Power Pillows from Hach (Part # 2105569) look like a good place to start. We have used the Hach powder pillows for other colorimetric measurements. (Link to download the Hach method sheet). I had a read through of the methods and it looks pretty straight-forward. Add a powder pillow to 10 mL of water sample in a glass container and measure absorbance at 520nm.
To use this method with our colorimeter, the first step would be to create a calibration curve which you would use to measure all of your test water samples against. To do this you would also need a chlorine stock standard and the equipment to make a set of calibration solutions (pipettes, glassware, distilled water). To each of the calibration solutions you would add a powder pillow and measure absorbance at 520 nm (or near). Once you have the calibration data (which you may only need to do once) you can then measure your water samples.
I would need to look into this some more to help with making the calibration solutions, but hopefully this information can get you started.