Although it has been said several times, I will try to say it even more simply and clearly. The simple truth is that, in most cases, the input sources and next loads are connected with one (negative) of their two terminals to the negative terminal of the power supply assigned as a zero reference …Circuit fantasist@ilkkachu, Thanks for the response. I mean the usual case for cascaded stages where the load is connected in parallel to the transistor. Really, here the load is connected in series to the transistor but that does not change things about the transistor (it is in the same place). tlfong014826@Circuit fantasist, your mentioning of “cascaded stages” and “load is connected in parallel to the transistor” seems to make things more confusing. It would be nice if you can describe you circuit in more detail, or better still draw a schematic, which will be much appreciated.I am trying to answer here your question “Where do you get this unbridled imagination from? And that subtle sense of humor? Maybe you are inspired by the Einstein’s thought about imagination:)? The reason of not answering not as a comment in the answer where I wrote my story of “imagination” (actually a “prediction”) seems to have disappeared into the future. / to continue, … Circuit fantasist@tlfong01, My answer was more general – about a multistage amplifier, where the output collector-emitter part of the current transistor drives the input base-emitter junction of the next transistor acting as a grounded load. Actually, I have explained why NPN but not PNP transistors are widely used to build transistor amplifiers… tlfong014826@Circuit fantasist, I see. So you have diverted a bit into analog amplifiers using push pull topology. Actually digital circuits can also do push-pull. I usually classify BJT digital buffer/driver outputs into three types: (1) Open Collector, sinking/pulling current from load, (2) Common Collector, sourcing/pushing current to load, (3) Push-Pull, can do sink/pull or source/push. The OP might like to see in my relay answer referred above, of examples of different output types in handling a relay. / to continue, …/ Continued, … (1) Class-B Amplifiers – Electronics Tutorials electronics-tutorials.ws/amplifier/amp_6.html (2) Open collector Output (Sink current from a load) – Wikipedia en.wikipedia.org/wiki/Open_collector (3) Common collector Output (Source current to a load) – Wikipedia en.wikipedia.org/wiki/Common_collector (4) Push-Pull Output (Can sink or source from/to a load) – Ecircuit Center ecircuitcenter.com/Circuits/pushpull/pushpull.htm. Cheers. Circuit fantasist@tlfong01, You are an interesting person with this “philosophical” reasoning… I see some resemblance between us:) I just cannot agree with the term “common collector”. Maybe “sourcing”, “sinking” and “sourcing & sinking is a more appropriate determinant before “open collector”? tlfong014826Sat 10:13(1)But open collector, common emitter, sink, source etc, are “official” terms used by the pros. You might like to watch this video RSD Academy – Open Collectors and Pull up Resistors youtube.com/watch?v=BH3u8E2UfSo, to see other pros are using these terms in an application of using opAmp(Comparator) to activate a relay, explaining the use of open collector, push/pull output, and pull up resistors etc.About my “philosophical” reasoning”, I have a BA degree in Philosophy and History, so I do have particular interest in using human language to explain hard to explain things (OK, like Einstein) and looking things in the past (PNP/NPN BJT) and predict things in the future (All MOSFETs in 2035). Predicting things in the near future is very important for IT pros in strategy planning and innovative/start up businesses. Ah, I also have an MA in Education, so I am interested to teach (or learn together) in a newbie friendly way, say, understanding by using metaphors. Perhaps more later. Circuit fantasist5004@tlfong01, Very interesting… I am glad there are people like you (and me:) here… and they have the courage to write that way. I am by vocation an inventor, a teacher and above all a “circuit thinker”. I try to find basic ideas behind circuits… and it takes me years. Then I explain circuits by building (reinventing) them step by step and showing their evolution. I do it by using human-friendly explanations, analogies… and by visualizing the invisible electrical quantities. My circuit diagrams are conceptual but then I show various applications. But I cannot find followers… Why? tlfong014826Sat 10:24I was curious to know why he doesn’t have any followers?. So I googled to find out, starting from the web page referred in his profile. I began to feel uncomfortable when I entered the web page. It took me less than 3 minutes to find out one big reason why he has no followers. Then I thought: (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, … 2 hours later… tlfong014826Sat 12:03(3) I am numbering my questions so that it is easier to refer to the subject we are discussing. Now it is a question that I am asking myself – Can my answers attract more followers and therefore hopefully more down votes? You might have noticed that my popular answer of JD-Vcc relay has 10 upvotes but actually I still want to improve it. It is sort of self appraisal, SWOT analysis, postmortem techniques.I know one of the good points of my relay answer are (a) It is on a subject JD-Vcc that causes confusion to many newbies. So I gave a comprehensive answer with a step by step learning case, with structured index, and (b) most importantly, with a lot of photos, and schematics.Now let me ask another question (4) that is more or less a tip to my questions (1) and (2). When answering questions on circuit design using BJT, MOSFET, OpAmp, beside schematics using CircuitLab, I also wanted to use LT-Spice. But I don’t know LT-Spice, so I am thinking of learning LS-Spice. Now my question to you it this, are you or have you been using Circuit, LT-Spice, or YouTube, TikTok, which I think should attract more followers? 5 hours later… Circuit fantasistSat 17:30@tlfong01, Again, I find that you are a very interesting person… not so typical of EE. I want to review your “popular answer of JD-Vcc relay” first to get an idea of how you think… and then I wll response to your message. Regards. 5 hours later… Circuit fantasist5004Sat 22:52@tlfong01, First, about you… Today I read your answer about “JD-Vcc relay” and I got a very good idea of your way of thinking. I saw that, in addition to your “philosophical” thinking, you also have very good specific thinking… and a very good style of presenting. So, I think there is a chance you can understand me. Although for the “Arduino boys” your answer is great and very useful, for me it is quite specific…… Here you can see some basic circuit ideas that are inherently electrical and were realized long before the “Arduino era” – even in the 19th century (well, not with transistors but with electromagnetic relays)…… Arduino is just one of many possible implementations of these basic ideas and all these details interfere with the understanding of the simple and clear (electrical) idea. It turns out that today people get acquainted with the basic ideas of elementary electrical and electronic circuits through Arduino…Now, about me… My purpose is first to reveal and explain the basic ideas behind circuits (concepts). I do it by using conceptual circuit diagrams with “ideal” and generic elements without specific values. Only then I show some specific implementations as examples.The power of this approach is that once understood the concept you can understand many other specific implementations. 4 hours later… Circuit fantasistyst 2:43In contrast, if you explain only the specific implementation and not the principle behind it, then you will have to explain each next implementation. In the first case, you will know (understand) only one principle, while in the second you have to remember many different implementations. 9 hours later… tlfong014826yst 12:01@Circuitfantasist About my “philosophical” way of “thinking” – First off, your use of these words is vague. (10) I have lost count of the points:) So let me start with 10. I always try to avoid using words like “philosophical”, “logical”, “reasoning”, because they are vague in meaning. Instead, I usually use words like how I “design” this circuit, how I “implement” this circuit. Actually I prefer to use how I “do” it. So I am sort of “Nike Just Do It”. So I sometimes say I am a “Nike Engineer/Guy”Actually I try to avoid to use the word “Engineer”, because this word is also vague. I am an ex-MIEEE, ex-MBCS, ex-CEng, because I am a slash freelancer, I usually call myself a hobbyist electronics/programmer. These two years I have been messing around with Micky Mouse smart home projects, so I can call myself a smart home hobbyist . To make my home smart, I need to use a little bit of AI, so when I meet some guys claiming that they are robotics hobbyists, I would say “me too”EE SE is actually quite vague or “multi discipline”, cover Electrical Engineering (for centuries means AC Power Generation and Distribution and Application (motors etc). Traditional Educational Institute such as MIT, still have the perhaps 200 years old EE Dept, and they even avoid using the word “computer/computing”, even thought they start doing AI in the 1950s with the AI language Lisp.So when I mess around with robotic, i actually use my knowledge of physics and mechanical engineering, and of course mathematics (applied and pure). I sometimes tell myself not to call myself an EE, because I think an EE should understand the basic concepts of “e”, “j”, Laplace/Fourier Transforms, can of course more basic things like capacitors and inductors. I am bringing up the subject “inductor” for the reason, which I would say more later. / to continue, … tlfong014826yst 12:35I have diverted a bit far, but I have not forgotten that your main questions is “How to attract more followers?” I usually try to find/tell answers from examples. Here are some examples:(1) OpAmps Tutorial – What is an Operational Amplifier? – EEVblog, 2014apr06, 1,733,493 views
(2) Operational Amplifier Basics – Electronics Tutorial
(3) Introduction to Operational Amplifier: Characteristics of Ideal Op-Amp – All About Electronics(see full text)I am a huge fan of EEVblog, so I usually watch their YouTube first (this example has 1.7 million “viewers/followers“I am playing with an analogue guy call “LoadCell” weight sensor and I am using a 24-bit ADC called HX711 to sense the weight down to perhaps 0.001g. I hope this would attract many “followers”. By the way, I am hoping to use LTspice to show off that the ok boomer does know some new tools, so this bad Arduino friends would not LOL at the face losing old guy that much, and begin to respect him more than he deserves.(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… tlfong014826yst 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:
Imported from a comment discussion on raspberrypi.stackexchang…1You 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. tlfong014826yst 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 fantasist50041:42Looking 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 fantasist50042:02This 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 fantasist50042:24Here 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 fantasist2:35In 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… tlfong0148269:06@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, …
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. tlfong01482610:43The Intern 見習冇限耆 – Official Trailer – 2015may13, 9,845,830 views
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
tlfong01482612:11Now 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: