tlfong014836Sun 12:43(4) Introduction to Operational Amplifiers with ***LTSpice*** – SparkFun
learn.sparkfun.com/tutorials/…Errata in chatting. I forgot to mention that what you chat in this room cannot be edited, meaning every mistake in on record. So I usually keep a record and summarize it as a PenZu diary, or as answer.I seem to have given the wrong web links in the above chat paragraphs. So I usually repeat the links to avoid visitor wasting time go back to find the correct link. The first YT I am watching is the follow in Dave Jones:(5) OpAmps Tutorial – What is an Operational Amplifier? -David Jones, EEVblog, 2014apr05
youtube.com/…  1 hour later… tlfong014836Sun 14:17One reason of learning op amp is that I am playing with a analog sensor, a load cellor, with a Wheatstone bridge giving ouput voltage in the range of a couple of milli-volts. I am using a 24 bit ADC HX711 to amplify it to a couple of volts, but there is a problem of instability, unreliability, etc. So one workaround to use an op amp as a pre amp to amplify the weak mv signal to volts. Then perhaps I use low resolution ADC such as MCP3008 (10 bit) or MCP3201 (12 bit), or ADS1115 (16 bit).This is the analog Load Cell with mV output and HX711 24 bit ADC chat record:

 Discussion between tlfong01 and Cem

Imported from a comment discussion on raspberrypi.stackexchang…You can see from the above chat record my way of “philosophical thinking”, actually engineering system development methodology in an anaglog and analog to digital projects. tlfong014836Sun 14:33You are right in commenting that I don’t look like an EE. Actually I am also interested in ISAD and ESAD (Information/Engineering System Analysis and Design and Practice) which does not focus in just hardware engineering systems but also software business information systems (methodologies such as Water Fall, UML, Rapid Prototyping (sort of meddling through), Agile etc). I usually recommend the following FREE eBook for enggr system development:System Engineering Analysis, Design, and Development: Concepts, Principles, and Practices, 1st Ed free eBook – Charles Wasson 2006
zu.edu.jo/UploadFile/Library/…@Circuitfantasist As you said, if you know the principles of one, you can do three. So If you know developing Business Information Systems, you will find it easy to develop Engineering systems. So I sometimes see myself an Engineering/Information System Analyst.  11 hours later… Circuit fantasist5014Mon 1:42Looking at the resources and everything you have written, I understand that you are one of those young people like the boys of Elon Musk who work miracles today. I just wonder where you got this energy and motivation to do all this. I see that you have broad interests and erudition. The book is great and makes me realize how limited I am.BTW around me are IT students who do similar developments in their diploma theses, some very interesting. Obviously, this is the spirit of the new age… and we, “old warhorses”, only keep the wisdom of the past.I have developed microprocessor devices but that was a long time ago. Gradually, I realized that my vocation is in finding powerful and simple intuitive explanations of basic electronic circuits.For years I have been looking for an answer to the question not only HOW they were made but also WHY they were made this way… and I was able to come up with reliable explanations.So if you feel the need to understand the idea behind op-amp inverting circuits, bootstrapping, dynamic load, negative “resistors” and other circuit phenomena, I can share it with you… Circuit fantasist5014Mon 2:02This is what I am actually trying to do here in SE EE but I meet fierce resistance from my peers and I am forced to do it in a hostile environment. Reactions range from passive (silence), negative (-1) to aggressive (hiding, closing, deleting and ultimately burying my questions and answers).Regarding why OPS beginners find it difficult to understand my explanations, the explanation is very simple – they do not have the attitude to think that way… Circuit fantasist5014Mon 2:24Here is just one of the latest examples – electronics.stackexchange.com/… where I have explained the behavior of a diode (in this case LED) at the lowest possible and understandable (even by a non-professional) level. The existing explanations are on a higher and more abstract level – something like “when the voltage approaches the LED threshold, the current starts to rise sharply”…The existing explanations are on a higher and abstract level – something like “when the voltage approaches the LED threshold, the current starts to rise sharply” … which is not actually an explanation but an observation. But why is the current rising? The next “explanation” is “because the IV curve rapidly changes its slope”… Circuit fantasistMon 2:35In contrast, my explanation is based on a simple but powerful concept – “dynamic resistance”. It is easy to understand (variable resistance), demonstrate (humble rheostat) and apply to any nonlinear element (diode, transistor, negative resistor…)  7 hours later… tlfong014836Mon 9:06@Circuitfantasist (1) Before I reply, I would like to suggest that we click the down arrow on left of the article we are referring.(2) One of my many reasons of visiting EESE and other forums (Yes, I have been hopping among more than a couple of forums every day), is to mend my broken English. Me on average, meet more than one new word everyday. This morning I learned a new word – “Erudition“.To learn a new word, I usually first goggle, skim a couple of dictionaries, and finally Wikipedia. Wikipedia says the following.Wiki – The word erudition came into Middle English from Latin. A scholar is erudite when instruction and reading followed by digestion and contemplation have effaced all rudeness, that is to say smoothed away all raw, untrained incivility, …

Meaning
Erudition is the depth, polish and breadth that education confers. The Latin word educāre means to bring out or train; hence an educated person has come to think critically and logically. An erudite person has both deep and broad familiarity with general subjects and is usually knowledgeable in a particular subject, by virtue of study and ext…(see full text)About “Erudition”, I can easily write a boring article of 30k+ words. But for now, let us chat something more interesting, that is “How can you and me, and EESE specifically (never mind generically), attract more “followers”)@Circuitfantasist You said this: “… around me are IT students who do similar developments in their diploma theses, some very interesting. Obviously, this is the spirit of the new age… and we, “old warhorses”, only keep the wisdom of the past.” –You remind me that I am a sort of freelance/slash teacher in computing science/computer engineering in industry (ie, the factory gave me the engineer, an assignment give a schedule of a series of talks of to teach the technicians and other engineers), let me, see, 1, 2, 3, 4, 5, 6, ah, I lost count, should be about 8 to 10, … 🙂Don’t ask me how many colleges and uni’s I studied, because I would lose count again, should be around 8, including two dropouts.I also from time to time, proposed / monitored / moderated / sponsored/interviewed / examined undergraduate level, individual/group term/year projects, including BCS (the British Computer Society then) Part 2 Qualification Project (sort of by practical project thesis/report)Yes, I am an erudicated guy, as our Chinese saying go: (1) gentleman hide deep and won’t show off, (2) People don’t know (that you know that much), but you could care less (because they don’t know what they don’t know (about knowledge you know).But there are times you should show your knowledge, skills, and experiences, to help/guide/mentor the young ones what you think is a good direction. When I was young, I did received help from the old guys, who I always think I should be grateful and so it is time for me to pay back.So you suggest: “Old warhorses, … only keep the wisdom of the past,“. This I don’t agree. I will explain, and I am going to propose projects for your students in the form of Q&A, in EE SE.Ah, morning coffee time. So see you later, perhaps after lunch, late this afternoon or evening. Nice chatting to you. cheers. tlfong014836Mon 10:43The Intern 見習冇限耆 – Official Trailer – 2015may13, 9,845,830 views
youtube.com/…

I heard the following MIT AI Corona Virus App news from BBC Radio this morning.Artificial intelligence model detects asymptomatic Covid-19 infections through cellphone-recorded coughs
Results might provide a convenient screening tool for people who may not suspect they are infected.
Jennifer Chu | MIT News Office Publication Date:October 29, 2020

news.mit.edu/2020/…tlfong014836Mon 11:21My literature research 🙂COVID-19 Artificial Intelligence Diagnosis using only Cough Recordings – digitalreality.ieee.org
digitalreality.ieee.org/…

DOI 10.1109/OJEMB.2020.3026928, IEEE Open Journal of Engineering in Medicine and Biology (Creative Commons Attribution 4.0 License)

tlfong014836Mon 12:11Now I have assembled a poor man’s cheapy Covid-19 AI cough recorder and real-time analyser.

@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:

 Discussion between tlfong01 and Cem

Imported from a comment discussion on raspberrypi.stackexchang…  2 hours later… tlfong014836Mon 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:

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… tlfong014836Mon 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. tlfong014836Mon 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… tlfong014836Mon 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 fantasist5014yst 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 fantasist5014yst 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 fantasist5014yst 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 fantasistyst 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 fantasist5014yst 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… tlfong014836yst 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． tlfong014836yst 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… tlfong01yst 12:42@Circuitfantasist Thank you for introducing your inventing article in codidact. I will go there and perhaps give comments there.  10 hours later… tlfong014836yst 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.

  6 hours later… Circuit fantasist50144:29Regarding 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… tlfong0148369:57@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. tlfong01483610:18To 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/…tlfong01483610:52UC 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)tlfong01483611:42Now 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… tlfong01483613:07To 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
youtube.com/…

(2) Raspberry Pi Compute Module 4 on sale now from $25 – Eben Upton, 155 comments 2020oct15
raspberrypi.org/blog/…

(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/…