hx711 chat

Mon 11:24

user image

tlfong014846Mon 12:11Now I have assembled a poor man’s cheapy Covid-19 AI cough recorder and real-time analyser.

user image

@Circuitfantasist “the idea behind op-amp inverting circuits, negative “resistors”, … I can share it with you …”. Ah I am only an op amp newbie. I learned op amp stuff when I studied my rusty EE diploma ages ago, but my work life since then have been all digital.I used to think that analog stuff is useless and has already been replaced by digital. But now I have a problem, I am calibrating a 100g load cell, with 0.01g accuracy. I am trying to use a 24-bit load cell amplifier, the HX711 to do the ADC. However the load cell output is of the range 0mV to 5mV, and though HX711 do handle the tiny signal, but it is slow 16sps.So I am thinking of using an op amp to amplify the signal and do some realtime processing, perhaps using JetsonNano with AI neural net stuff, to analyse the coughs of Covid-19 guys. I have only recently started the project, originally for testing a wind tunnel. But the wind tunnel project failed, so I started again, switched to Covid-19 coughing analysis, hoping to attract more “followers”.This is a recent progress report of the failed wind tunnel project, in case you are interested:

Raspberry Pi Discussion between tlfong01 and Cem

Imported from a comment discussion on raspberrypi.stackexchang…  2 hours later… tlfong014846Mon 14:54@Circuitfantasist I am a little bit confused. (1) I know “normal resistance” is “Ohmic”, means that R = V/I is more or less a constant, or I vs V is “linear”. (2) I also know that semiconductor devices such as a diode is “non linear” or “exponential”.(3) I also know that “dynamic” is time varying. (4) I once played with NTC (Negative Temperature Coefficient (NTC), where R vs I is linear but gradient is negative. When I increases, T increases, R also increases, and I decreases (V constant, a step function or an impulse function). So NTC it is sort of dynamic, because I changes as R, T changes.My “negative resistor” electronics.stackexchange.com/… looks like this:

user image

Now I have a couple of questions: (a) In defining or specifying you negative resistor characteristics, what are the (i) dependent, and (ii) independent variables? (b) Do you have any defining equations or graphs to illustrate your negative register idea? (c) How is your negative resistor different from the NTC resistor?  1 hour later… tlfong014846Mon 16:31I can suggest Covid19 student projects in this EE SE Q&A. I usually visit various college project site to see what is going on there. This is one of the sites I regularly watch inspire me hobbyist project ideas: Cornell University ECE5725 Spring 2018 Rpi Student Group Projects
skovira.ece.cornell.edu/…If your students are mainly doing individual and not groups, spending time shorter than a semester, or EE minor students not so experienced in ENC/MPU/SBC, you can split a big project into small parts to make it more newbie friendly. For example, for the Covid19 cough analysis project, you can split it into the following parts: (1) Cough capture, using linux audio utilities with microphones, with low resolution ADCs, such as MCP3008/3201.(2) Use Rpi4B and TensorFlow Lite to play with Google supplied classic basic test patterns such as recognizing numerical “0”, “1”, “2, … “9” etc.I have a couple of Covid19 related project ideas: Here is one:
How can Rpi read the MAX30100 / MAX30102 Oximeter? Rpi EE, 2020may01, Viewed 2k times
raspberrypi.stackexchange.com/…I have also played with air pumps, air flow meter, high torque serial bus servos (LX-224) for Covid19 related projects like this: “Coronavirus: Raspberry Pi-powered ventilator to be tested in Colombia – Zoe Thomas, BBC 2020apr13”
bbc.com/news/….Ah, jogging time. See you late this evening or tomorrow, Cheers. tlfong014846Mon 17:26Before I go, let me comment on your Q&A: Circuit Phenomena Have Dual versions – Cyril Mechkov, Technical University of Sofia, 2013jul07,
researchgate.net/post/….You said the following: “Circuit phenomena have dual versions: voltage/current, resistance/conductance, positive resistance/negative resistance, capacitance/inductance, positive feedback/negative feedback, amplifier/attenuator, integrator/differentiator, low-pass/high-pass, series/parallel, etc… “I am relearning op amp, and I am focusing on op amp integrator and differentiator and you idea of dual phenomena is helpfully inspiring to do a “deep learning” of the op amp. Usually I think of unthinkable things while jogging, and DUAL is the subject of my jog this time. Cheers.  4 hours later… tlfong014846Mon 21:56I suggest the MIT AI Cough Covid19 test for the following reasons. The discrimination between positive and negative Covid19 is much easier, and takes less computation power than discrimination of 10 sounds say “Zero”, “One”, “Two” … “Nine”. A start off warm up project might be just a humble discrimination between two classes, child and adult etc.  4 hours later… Circuit fantasist5030Tue 2:06@tlfong01 @tlfong01, I am beginning to respond consistently to your comments because today I was finishing my second “inventive” article on Codidact (electrical.codidact.com/…) and only now I find time to write to you. Just to ask you, because I have no experience in chats, is it normal to chat here indefinitely? Maybe it would be better to do it in the right places – below the appropriate questions and answers? Circuit fantasist5030Tue 2:49Regarding “common collector”… I see what you mean but it is better to say “open emitter”. “Common collector” is reserved for AC (small-signal) applications when the base and emitter voltages vary but the collector is firmly fixed to VCC. Here we are talking about digital applications where the base voltage is fixed at zero or VCC.@tlfong01 To “(1) He knows the answer already, but does not want to tell. If that is the case, then he is not honest, (2) He does not know the answer. It that is the case, then he is stupid,…” add (3) He knows the answer already and he wants to tell. This is my case. Circuit fantasist5030Tue 3:07@tlfong01 I know I have to use simulating software but I do not use it for a variety of reasons. First, I have to work hard to master it so that it is useful to me. Second, I know I am going to start thinking less about circuit phenomena. Third, it will reduce my enjoyment of mentally finding a solution. But sometimes I do some real experiments to test some of my assumptions.  2 hours later… Circuit fantasistTue 4:43@tlfong01 Saying “philosophical” I mean “conceptual”, “generalized”… Most people think specifically and do not make a connection between the individual specific implementations of the same idea. As the saying goes, “they can’t see the forest for the trees.” Understanding a circuit requires seeing the general idea behind it. Circuit fantasist5030Tue 4:55@tlfong01 I got a good idea of you. I have always been interested in how programming combines with technology (software with hardware)… since the former is abstract and the latter so tangible. I am much more limited and all my life I only deal with circuits…@tlfong01 These op-amp resources are good but standard. I need more in-depth explanations from people who have a “philosophy” and want to share it. Unfortunately, I can’t find any, so I’ve been trying to make it myself for years.@tlfong01 24-bit ADC sounds fantastic. I just can’t imagine such a resolution. But I don’t think you can use all its bits because of the interference.@tlfong01 Regarding Sparkfun op-amp tutorial… Look at the inverting amplifier. Do you understand what is the need of R1 and R2? I was trying to answer this question as a student in the middle 70s (en.wikibooks.org/wiki/…  4 hours later… tlfong014846Tue 9:05Ah, you bring up a critical engineering trade off between accuracy and usefulness. Let me give an example: (Arduino built in ADC GPIO has 10 bits accuracy (I prefer using the word “accuracy” over “resolution”). The very popular MCP3008 also has the same accuracy. Now let me see. 10 bits means 2 to the power 10 = 1024. So the accuracy is 1/1024 = 100/1024% ~= 100/1000% = 1/10% = 0.1%.Now suppose there was an earthquake, and the slanting tower somewhere in Europe seems to have slanting “a little bit more”. Now if the Tower owner wants a risk analysis report. So he makes a tender, and me and my bad Arduino friend are bidding. In the briefing interview, the panel asks my bad friend: “So you are saying the P Tower is OK, because Arduino is OK, with a risk of the order of 0.1%, ie, 99.9% safe. Now when it come to my turn, I will say, I can give your 0.01% assurance.But then ADS1115 engineer says: “tlfong01’s quarantee is bad, I can give you at least 1000% more confidence. Now the owner says, OK, now I will take the ADS1115 guy. But the HX711 guy, ie, me, says “What ever the ADS guys gives you, I can give you 1,000 times more”. Of course the ASD is prepared, because he has prepared his 24 bit ASD1250 data, and said, “what tlfong01 gives you, me HX711 can do as well”. Of course I won the contract.The above is only the beginning. I have not touched the crucial part, engineering accuracy/reliability (MBF)/worst (black swan) case trade off, and business cost/benefit analysis. Now let me suggest the following. (1) You tell my story in broken English to you students in their mother tongue, and give them an assignment to write my story in English, and ask them the following question: (a) is it a bad idea to use HX711 which has more than enough bits to use?(b) OK, so you have more than enough bits, so what do you do? Give me a market strategy plan for the sales enggr team, …@Circuitfantasist Your comment ” I was trying to answer this question as a student in the middle 70s” makes me laugh”. Let me, before I forget, why you don’t have tan many followers”. As I said earlier,Sorry, system error, will back back later, when fixed. tlfong014846Tue 10:20Earlier my Chinese Windows 10 got crazy and wrote funny characters. Now let me carry on. So I visited the guy’s web site and hoped to see why he has no customers (followers in his words). I clicked the web site, and the first ugly unfriendly screen is a short note, say something like “need to use Flash”. WTF, so the student, ie, me tried to clear his mind a bit, and remembered that he has not used Flash for perhaps 10 years. And there is no flash installed by default in his CWin10.Anyway, so he googled to installed Flash, but WTF, he got the instruction that he need to download Flash from IE, Internet Explorer (he needed to spend 5 seconds to guess what “E” in IE means). OK, but the miserable student forgot how to start IE, or actually he has installed IE, though he know how to start Fox. He went of Chrome and found he can download and install Flash. OK, he installed Flash and successfully install the F**** and hope to visit the site.But WTF, the F**** before starting, gives a “friendly” reminder something like below: “This is a trial version, which you can use for 7 days, after that you MUST buy a licence for HK$499, … . This reminds the student that Flash is a dead interface, already replaced by HTML5 some 5 or more years ago. WTF!!!  2 hours later… tlfong01Tue 12:42@Circuitfantasist Thank you for introducing your inventing article in codidact. I will go there and perhaps give comments there.  10 hours later… tlfong014846Tue 22:26Now I am setting up the hardware test part of the Covid19 Cough Analysis Project. I am setting up two identical sets of load cell for easy auto/self test/troubleshooting/calibration procedures.

user image

  6 hours later… Circuit fantasist5030Wed 4:29Regarding Flash… I created circuit-fantasia.com in 2002 in cooperation with Poptronics (the former Popular Electronics). It had to be impressing to attract readers. Macromedia Flash was the most powerful tool for creating interactive animated stories. And really, they became (too) impressive. Now I have no idea what to do. I wonder if there is some way to convert them to something workable…Inside the site, there are ordinary HTML pages, e.g. ‘Circuit stories on the whiteboard’ (circuit-fantasia.com/…) or My students 2004 (circuit-fantasia.com/…).  5 hours later… tlfong014846Wed 9:57@Circuitfantasist Flash 2002, It had to be impressing to attract readers, … – Yes, but anybody even just mentioning the word “Flash” would be LOL’ed as a dinosaur, …For your reference:(1) Adobe Flash Player – Wikipedia
In July 2017, ***Adobe*** announced that it will end support for Flash Player on December 31, 2020,*** and continued to encourage the use of ***open HTML5*** standards in place of Flash. The announcement was coordinated with Apple, Facebook, Google, Microsoft, and Mozilla. All major web browsers plan to officially remove Adobe Flash Player on December 31, 2020, and Microsoft will be removing it from the Windows OS entirely in January via Windows Update.(2) Thoughts on Flash – Wikipedia
en.wikipedia.org/wiki/…Flash globally ending by 2020 – In July 2017, Adobe announced its intention to discontinue Flash (including security updates) altogether by the year 2020. tlfong014846Wed 10:18To attract readers, you must include the word “Covid19” everywhere, like following. 🙂FluSense, Rpi device with neural engine, listen for coughs to help identify Corvid19 and flu like symptoms – Inventors Digest, 2020nov02
inventorsdigest.com/articles/…And to attract readers, you need to tell everybody that you are zoom friendly, even your physics labs. That is why I am developing a zoom friendly version of my poorman’s Micky Mouse copycat MIT AI Covid19 Cough Sensor Experiment Kit. 🙂COVID-19 Remote Control (Zoom) Physics Lab at Your Fingertips – Harrison Tasoff, Current Science + Technology, 2020nov02
news.ucsb.edu/2020/020077/…tlfong014846Wed 10:52UC Santa Barbara’s Phy Dept guys has ***invented*** a Rpi based, 24/7, pandemic/zoom friendly, affordable, remote control lab, with stepping/servo motors, camera, 3-D printer, real potentometer knobs, …

So the students, instead of playing video games or watching YouTube at 2 in the morning, they can hop online and push a button or turn a knob for greater precision in their measurement of Planck’s constant, .. in short, more power to them. Students can propose, execute and report on a physical measurement they could perform on their own.(see full text)tlfong014846Wed 11:42Now I am thinking which Neuro machine to handle the cough data collected by the Rpi CM4. One candidate is the following cheapy US$60 Nivida DevKit:NVIDIA Jetson Nano 2GB DevKit (Arm Cortex-A57 (Quad Core), Maxwell GPU (128 CUDA core) US$59 – Dave Altavilla, 2020nov03
forbes.com/sites/…  1 hour later… tlfong014846Wed 13:07To attract readers, you must no longer mention the old guy Anono, which might damage your reputation. You should love the new guy Rpi CM4, or at least the growing fast STM32 Cortex M3~M0 family.(1) Raspberry Pi Compute Module 4 – Rpi, 2020oct19

(2) Raspberry Pi Compute Module 4 on sale now from $25 – Eben Upton, 155 comments 2020oct15

(3) Raspberry Pi Compute Module 4 – 1GB RAM SKU 102991380 – Seeedstudio, US$25
seeedstudio.com/…(removed)(4) Raspberry Pi Compute Module 4 Product Sheet/Documentation – Rpi, 2020oct19
raspberrypi.org/products/…(removed)(5) Raspberry Pi Compute Module 4 Pricing – raspberrypi.org
datasheets.raspberrypi.org/…  11 hours later… Circuit fantasistThu 0:44These are great miracles but simple circuit phenomena are my passion … I am currently developing my next inventor’s story only with the help of my experience, imagination, sheets of squared paper and colored fiber pens 🙂  1 day later… tlfong014846Fri 9:20@Circuitfantasist At least you should include the following news in any of your pages that has Flash.Adobe Deprecates Flash Components In Reader And Acrobat Products – Danish Ansari, RepublicWorld, 2020nov05
Adobe has revealed that it is removing all the Flash components in its Reader and Acrobat products. The technology is set to end by the end of this year. tlfong014846Fri 9:33@Circuitfantasist You mentioned that you have IT students around you, and they might be future Elon Musk’s. So I am suggesting some college level IT projects your students might consider.I often try to recommend IEE and BCS (yes, they are old names) to my young digital makers.(1) Celebrating Future Engineers – Katie Gouskos, 2020nov04

(2) This is Engineering
thisisengineering.org.ukThe HX711 Covid19 Cough Sensor Project Proposal is cheap and can be done at home.(3) Digital Making at Home
raspberrypi.org/at-home/…tlfong014846Fri 9:48(4) This is Engineering – Farming Future

user image

I have been blogging and answering questions in rpi.org.forum and RPI SE on using HX711 for smart city and home automation. This is a recent example.(5) HX711 Based Smart Farm Automatic Vegetable Weighting
electronics.stackexchange.com/…tlfong014846Fri 10:46So your students can actually do digital making at home, with the basic hardware below:(1) Rpi CM4 – US$25(2) HX711 – US$20(3) Loadcell – US$20(4) Misc – US$35(5) Total – US$100

user image

  23 hours later… tlfong014846yst 9:20@Circuitfantasist Well, my suggestion on Covid Cough Signal Analysizer is for your students, perhaps supervised by you and/or your teaching colleagues. For you invention passion in circuits, it would be nice if you can make them or suggest how to make them as a practical engineering useful in real life, as I am saying, helping to fight against Covid19.  6 hours later… tlfong014846yst 15:23@Circuitfantasist But I watched the video by Dave Jones and found it very good to explain most of the basic things about op amp. His two fundamental rules of op amp, and the idea of “virtual ground” is very good. On the other hand you circuit diagram is a bit messy. So I think your students won’t be that impressed. Perahps you can also make a youtube video to explain you ideas.  4 hours later… Circuit fantasist5030yst 18:57@tlfong01, I don’t know why but I can’t reply to a specific message from my phone… OK, let’s begin from your last message. Regarding Dave’s movie… It’s a big show with a lot of words and gestures, something like a Hollywood movie. He says many things but explains almost nothing … or he does it on the usual formal level…In other words, “Much Ado About Nothing”… But I have watched it briefly… OK, I will watch it to see if there is something different in its content (not the form) than the usual web texts… Circuit fantasist5030yst 19:14My circuit diagrams look “a bit messy” because my goal is to provoke student’s (reader’s) creative thinking. If I had time and space enough to expose my idea (because I always have an idea to explan), you (readers) would understand all. This can’t happen here in SE EE but I have done it on my site, in Wikibooks and ResearchGate…The true understanding of circuit ideas requires a very good contact with the person you are explaining to and goodwill on his/her part (what is missing here). My students always understand my explanations in the lecture hall and the laboratory because there is a very direct connection between them and me… and I don’t stop explaining until I’m sure they understand me. Circuit fantasist5030yst 20:13I will share a wisdom with you because you are benevolent and want to understand my way of thinking. It reads as follows: To truly understand the idea behind ​​a circuit, you need to know where the currents flow inside it. Each current starts from the positive terminal of the power supply and returns there to its negative terminal. That is why I present the currents with their full loops (in green, from the association with running water).Also, to truly understand the idea behind ​​a circuit, you need to know what the voltages across its elements are the connection between them. That is why, I present voltages “geometrically” by voltage bars (in red). They can be easily summed according to KVL thus showing the relation between them…This geometric way of presentation is much more visual than the digital way used in simulation programs with very varying digits after the decimal point… which is meaningless for the purposes of understanding.  1 day later… Circuit fantasist21:06It’s been a day since I wrote this “wisdom”. During this time I managed to make a new inventor’s story and just published it – electrical.codidact.com/…tlfong014846@Circuitfantasist I very much with you that you must know KVL inside out before you claim that you understand electrical circuits. But there are other laws you also need to understand thoroughly as well, say the three guys below:

user image

And if you need to dig deeper to know the laws the govern the components that make up the circuits, namely: R, C, L, so you need to know the guys at a deeper level, eg Faraday, Lenz, and so on. So we come to Maxwell’s who play with Electromagnetism, and Schrodinger who play with cats. Of course we have left superficial and shallow EE stuff and hit physics, and still deeper, mathematics, .. Of course we are meeting Einstein and Hawkin, but there is another lady we need to know.If you don’t know this lady’s stuff, you cannot say you know the origin of inductor’s back EMF.The time has come to introduce this lady:

user image

To know more about Emmy Noether: BBC Radio 4 In Our Time 2019jan24


Categories: Uncategorized

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.