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Andras

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  1. Alright, I finished the tests for today, here are the results. I used "traditional" yeast now, and not the brewer's yeast as before. (A - blue - left) 27 Celsius water + 2.5g glucose + 2g yeast (B - red - middle) 27 Celsius 2.8% milk + 2.5g glucose + 2g yeast (C - green - right) 50 Celsius 2.8% milk + 2.5g glucose + 2g yeast [please note that all the temperatures converged to our room temperature in the end to 28 Celsius] The following two pictures were taken 5 minutes (light color) and 120 minutes (darker color) after mixing the ingredients together. And the impedance values in the 100 Hz - 2 kHz range: As a next step I will try to write a small script to make single impedance measurements every 30 seconds or so, and plot the changes over time, so that I could see the rate of the change over time.
  2. Hello @Cleber Borges Today I tested a few things: I made a measurement before and after cleaning the electrodes and I did the same before and after I whirled the mixture. Neither of them modified the values, which is good news. I have found one interesting thing though: if I make the impedance measurement while the temperature sensor is submerged in the mixture, it distorts the values in the 20-25 Mhz range. I use a multimeter to measure the temperature, so from now on I will not keep its probe in the mixture, and I will put it into the fluid only for a few seconds when I actually check its temperature. I can't tell at the moment if there is any gas formation, it looks like there isn't any. It can be because I set one parameter or ratio wrong. According to the literature my room temperature is higher than the ideal (it's 27-28 Celsius here) and the ideal would be somewhere below 20. Today I added salt to the mix, because the minerals are said to be critical for the yeast as well. Here are the results after 3 hours: (tap water + glucose + brewer's yeast + Himalayan salt) Since my goal would be to detect the phase of the yeast + sugar reaction with this impedance measurement, I will change the measured range to 100 Hz - 1 kHz, it looks like most of the changes are there. According to the data the reaction starts right away, but it stop after about 2 hours. This, again, can be because I use wrong ratios or at a wrong temperature, I need to make more tests. Andras
  3. Alright, so I made 9 consecutive measurements in 10 hours on both tap water and the yeast + sugar + water mix. The results for the water are the following: And results for the yeast: The values are changing for both over time, which is expected, but there are a few strange things: - The first tests for both are not in line with the changes happening later, they look off. - The amount of changes for both samples are similar, does this mean that it doesn't matter if it's something living like the yeast or non-living like tap water? - I'm not sure what the reason for the changes are: Could it be the little temperature fluctuation during the day? Could it be that the evaporation from both containers? - It's not proven yet, but I got the suspicion that small bubbles form on the electrodes during the time between the tests and they change the measured values. Would I get different results if I shook them or didn't shake the electrodes before the measurements? Also, I'm not convinced that the yeast started to work today. I can't really tell, I need to get more information about the brewer's yeast and its properties.
  4. Hi @Cleber Borges and @attila, Sure, my electrodes are simple wires fixed at a certain distance from each other, and they look like this: Do you know what kind of electrodes researcher normally use when they do EIS? It's interesting that you just mentioned the voltages, I tested them as well, because I feared that the high voltages would make changes in the target fluid especially if it's a living thing, like yeast. So here is the test I had, comparing the different amplitudes/voltages: Probably it isn't obvious on the screenshot, but the 5 mV - 50 mV charts are fuzzy, I think that amplitude would be not good for testing. 100 mV is the first value that looks ok to me, so I will start using that one from now on I repeated a few 100 mV tests a few hours apart on my current fluid sample which was tap water + glucose + brewer's yeast. The result were not consistent: I suspect that it is because there were some reactions going on with the sugar and yeast, so today I'm going to repeat the tests with a control sample of tap water, and the same glucose + yeast combination.
  5. Before I continued my tests with beer, I wanted to make sure of two things: a, the amount of the sample fluid does not influence the impedance values b, the measurement itself does not change the sample fluid so that its impedance is changed at every measurement For case A, I made 3 references with 1 cup, 2 cups and 3 cups of tap water. I used the same source and the same container for all the measurements. Then I made 3 other measurements of the same 3 cups of water. At this point I can conclude that the measurements are fairly harmless, there is only a small amount of change on the dataset after each consecutive measurement. I could probably use lower voltages, which could theoretically reduce the impact further. The amount of the test fluid does change the dataset somewhat, so I will keep that in mind when I go ahead with my further tests and I will try to keep the volume of the fluid fixed. As we could see from my previous post, the temperature is very important, so that's another parameter I will try to manage and keep constant between the tests.
  6. Hey guys, I've made some experiments that could be interesting for your as well. I put tap water into my ceramic container, I heated it to different temperatures and measured the impedance every 5 degrees. You can see the values between 60 ° Celsius (140 ° Fahrenheit) and 5 ° Celsius (41 ° Fahrenheit). Red is 60 Celsius, blue is 5 Celsius and there are 10 steps between them.
  7. I did a quick experiment with different liquids. All of them are in a small ceramic container. The blues (Ref1, Ref2 and Ref5) are tap water. The red (Ref3) is salted water. The green (Ref4) is carbon-filtered tap water. I just put both the + and - wires of the Impedance Analyzer into the container and I made sure they are not directly connected. Here are the results: Cool stuff!
  8. @Cleber Borges, I'm sorry to hear that! I had to wait a few weeks as well here in Hungary, but it wasn't as bad as in your case. If you have no other option, let me know, I buy you one here and send it to you to Brazil. If you had the Impedance Analyzer, how would you make the measurements? I saw your other post: The Impedance Analyzer has only two wires: + and - So, would you put just those two wires into a liquid and run the Impedance Analyzer tool in WaveForms? Would you expect to get consistent result for the same type of liquids? Thanks! Andras
  9. Hi guys, This is a fascinating topic! @Cleber Borges, did you end up using AD2 as a FRA (Frequency Response Analyzer)? Do I understand it correctly that you did experiments with fluids? Did you get consistent results? Could you share your settings with us? Thanks, Andras
  10. Szia @attila, Now that Raspberry Pi 4 Model B is out, do you see any chance that WaveForms will work with it?
  11. Szia @attila, alright, thank you for making it clear!
  12. Thanks @rprr for posting a bug report on Raspberry's GitHub. I also have a Raspberry Pi 3 Model B and it would be great to have WaveForms running on it. There is a suggestion on the FTDI Community forum to try a 3rd-party library called libFTDI, they think it might work. Has anyone tried to compile it and use it with WaveForms? I tried the following, but my Linux knowledge ends here sudo apt-get install cmake libusb-1.0 git clone git://developer.intra2net.com/libftdi cd libftdi cmake . And I got this error: Could NOT find Confuse (missing: CONFUSE_LIBRARY CONFUSE_INCLUDE_DIR) @attila, do you see any chance this could work?
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