(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/…  11 hours later… Circuit fantasistNov 5, 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… tlfong014886Nov 6, 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
republicworld.com/…
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. tlfong014886Nov 6, 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
raspberrypi.org/blog/…

(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/…tlfong014886Nov 6, 9:48(4) This is Engineering – Farming Future
youtube.com/…

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/…tlfong014886Nov 6, 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

  23 hours later… tlfong014886Nov 7, 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… tlfong014886Nov 7, 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 fantasist5397Nov 7, 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 fantasist5397Nov 7, 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 fantasist5397Nov 7, 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 fantasistNov 8, 21:06It’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/…. tlfong014886@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:

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:

To know more about Emmy Noether: BBC Radio 4 In Our Time 2019jan24
bbc.co.uk/programmes/m00025bw  4 hours later… Circuit fantasist5397Nov 9, 1:45Thanks for all the resources. I have contact with our IT students only in the initial courses where I introduce them to basic circuits. Then I lose touch with them. My disciplines are not much desired by them; they want to deal with software. Such are the times… and there is no developed electronic industry here either (there was… but now it is destroyed). So they emigrate abroad en masse… Circuit fantasist5397Nov 9, 2:01BTW I took an hour today to watch this RSD movie – youtu.be/05ffk8bJdg0. This guy gave me pleasure because he made a live demonstration of the operation of the inverting amplifier that I have been using since the 80’s. I think I have something to say to these guys (he and Dave) as long as I can make contact with them. I look for such people on the web … who understand circuits … but I still can’t find them … Circuit fantasist5397Nov 9, 2:18Then I began watching the Dave’s movie about op-amps – youtu.be/7FYHt5XviKc but I didn’t last until the end, I’ll watch it some other time. What he tries so hard to explain (inverting amplifier) ​​is very easy with a simple demonstration. Two variable voltage sources (the one is the input voltage source, the other is the op-amp output) of opposite polarity are connected to each other through a network of two resistors (R1 and R2) in series.  1 day later… tlfong014886Nov 10, 10:09@Circuitfantasist I very much understand the rise and fall of the electronic industry in your place, because it is very similar to my city’s industries (not just electronics, but across the board, except the finance and property sector). I agree that your students are wise to choose computer software and forget hardware. / more about this later, … tlfong014886Nov 10, 10:55About RSD Academy – Bob DuHamel, 2016
youtube.com/channel/…

You have been watching Ben Heck, Dave Jones (EEVBlog) and Big Clive. You like what you see and want to work in electronics. Your forte is troubleshooting and repair so you want to be an electronics technician. Where do you get started?

Many universities four-year electrical engineering programs. This is great if have the desire, time and money to become an electrical engineer, but there are few schools that teach electronics at the appropriate level to train technicians.(see full text)  1 day later… tlfong01Nov 11, 11:00This post is about negative resistance. Any comments? electronics.stackexchange.com/…  17 hours later… Circuit fantasist5397Nov 12, 3:53Thanks for the link. This is a typical example of how a simple idea can be presented in an insanely complex way to become a scientific article.It seems to me that this idea is familiar to me, perhaps from diode functional converters with a segment approximation… or from my LED voltage indicatoThis is an example of artificially created differential resistance. Actually it is “over dynamic resistance” (I have explained it in en.wikibooks.org/wiki/…). Cheers!Bob DuHamel is an amazing phenomenon. It gives me great pleasure to watch it. Circuit fantasistNov 12, 4:54Well … I decided to sacrifice an hour of my precious time to write a deeper answer (electronics.stackexchange.com/…) although no one will appreciate it there…  4 hours later… tlfong01Nov 12, 8:26(1) Well, you can be sure that no prophets are liked by the people of their own hometown (Luke 4:24), (2) And, why not be water my friend? imdb.com/video/vi2435890713? Cheers.  2 days later… Circuit fantasistNov 14, 4:15@tlfong01, Thanks for the wisdom. I think here “prophets” are not only disliked but they are even persecuted and expelled… Circuit fantasist5397Nov 14, 4:36I became very interested in Bob DuHamel because I find that we look at circuits in the same way.The only difference between us is that his explanations are more specific and oriented to technicians, while mine are more general and “philosophical” and intended for creative thinking people (inventors, students and curious people like you).

My explanations can also be useful for professionals but they have great self-confidence and are envious. Just look at how he presents diodes and transistors as dynamic resistors. Maybe he borrowed some of my ideas…  4 days later… tlfong01Nov 18, 11:00This is another question you might be interested, and give a “philosophical” comment: . electronics.stackexchange.com/…. I think this is an example that you need to think deep, deeper than EE circuit, down to physics, through mathematics, to philosophy, and knock at the “Creater’s ” door.  5 days later… Circuit fantasistMon 5:47@tlfong01 Hi again! Really interesting topic for me… Do you have Flash player? If so, visit this page and play with the Flash movie at the bottom; it is about the inductor property discussed here. You can write me to my gmail (cmechkov) and I will send you more interesting links. Cheers!  4 hours later… tlfong01Mon 9:42@Circuitfantasist Sorry, I can only use free HTML5, not Flash which is NOT free. Perhaps you can convert your Flash into animated GIF, or something similar.  2 hours later… Circuit fantasistMon 11:49OK, I will try a converter but I don’t know if the interactivity will stay. Anyway, write me … tlfong014886Mon 12:46@Circuitfantasist Actually I usually think that a Yuotube video, with a couple of power point style slides, sort of a slide show, with good annotation can explain an idea well. Of course the video should be accompanied by text and still /pictures/image/short (perhaps 5 to 10 seconds) mp4 videos based tutorials, …I am now thinking of making such a YouTube + Text/image based tutorial. The first big subject that came to my mind is negative resistance, narrowing down to tunnel diode, further narrow down to “How to plot the I-V curve of a tunnel diode”, …My teaching/learning plan is to start with a Schottky/flyback diode, with the classical diode IV curve and the “diode equation”, explaining ideas of load lines, then move on the negative resistance, tunnel diode, plotting the curve, designing three loading lines for monstable, bistable, astable operation mode, and move on to designing a ultra high speed oscillator, comparing with Gunn diodes etc, etc, …I admired your Lancaster elegantly simple tunnel diode curve tracer with minimal simple components of ac mains lines 50Hz and transformer, 1k resistor, Tektronix socpe, … My objective is to do something similar, using a triangular wave say 400kHz to do a similar. I am guessing if I use my cheaper Rigol storage scope, and adjust time base to look at the negative resistance region, … A quick and dirty picture is shown below, …(removed)

Now you can use animated GIF to do the animation, with in picture colour highlights, or YouTube talk show, with mp4 slow motion pictures, … just quick and dirty thinking aloud, sorry for all the typos. Ah locking down lunch time, I need to go, see you late this evening or tomorrow. Cheers,Ah, I forgot to show you the easy to adjust cheapy ICL8038 sig gen (with up to 450 kHz, to replace your 50Hz transformer sweep time base). I forgot if I already showed a day ago, …

  3 hours later… tlfong014886Mon 15:46Now I have tidied up my hardware test setup. The foot print of the proto board is only of A2 size (15 x 22cm). So that in our maker’s club, each two participants can sit socially distant in front of a desk and do the experiment. They can also borrow the test kit and do their covid-lab-from-home experiment.

tlfong014886Mon 16:38Now about the I-V graph confusion. I very much agree with you that for two variables graph such as ours: (1) Current It is dependent variable, so should be represented as the Y-axis (ordinate), (2) Voltage Vt should be represented as the X-axis (abscissa). And as I pointed out earlier, the Vt range is too wide for Excel to draw a graph properly, So I tried to invert the X-Y graph to Y-X but the result is no good. Now I am thinking of drawing two graphs,(a) before the Vt for Ipeak, (b) after the negative region jump over. But I have little confidence that I am doing the correct thing. So I am uploading the Excel worksheet to my GibHub site，　．．．My GitHub site address is:github.com/tlfong01/…My GibHub’s licence is MIT. So you are free to download anything there to try things out. Later I will upload my python programs of ADC MCP3008/3201/3208 for the voltage conversions of the differential voltage across the Tunnel Diode (to get It vs Vt). Then I can ask Rpi4B Thonny python to plot the IV curve, without stupidly taking any manual readings using multi-meter, and use Excel later.  6 hours later… tlfong014886Mon 22:19Before trying the triangle wave sig gen, I am testing another tunnel diode part number 2SB4 sample #1. I happily got reasonable measurements, as shown below:

This time I did not waste my time trying to plot a complete curve using Excel, because I said earlier, the voltage range before jump over is 0~20mV, and after jump over is 486 mV ~ 500 mV, with stable increase of It around 1.88 mA. This time it is not a clear cut jump over, but can use adjust PSU to get unstable readings such as 194, 206, 221, 241, 250 mV. tlfong014886Mon 22:54Now I am randomly browsing EE SE’s old Q&A in the past 7 years or so, to get a rough idea of the EE SE guys here have been discussing. As I have expected, a Q&A forum are for short questions and short answers, so no deep level knowledge and skill can be covered. One useful thing is that I can find good reference pointer. An example if the 60 year old GE manual on tunnel diode.I skimmed the guide and I am glad to know how the engineers 60 years ago are doing R&D and enggr applications then. This is the guide and I skimming. I found the following topics useful: curve tracer, oscillation design, specification examples.Tunnel Diode Manual (including Curve Tracer, Oscillator Design, Load Line, Specification) – GE 1961
archive.org/details/…
ia902701.us.archive.org/3/…Corrected Links – Tunnel Diode Manual (including Curve Tracer, Oscillator Disgn, Load Line, Specifiction) – GE 1961
(1) archive.org/details/…
(2) ia902701.us.archive.org/3/…  8 hours later… Circuit fantasistyst 7:20Very interesting…  3 hours later… tlfong014886yst 10:35I found my GitHub site on Tunnel Diode a bit too professional, and might scare the newbies away. So I decide to open a blog under my Google Account, dedicated to Tunnel Diode.My Tunnel Diode Blogger Blog’s address is:tlfong01’s Blog On Tunnel Diode
tunneldiode.blogspot.com  4 hours later… tlfong014886yst 14:08Your suggestion of swapping X and Y axis is good. I also found I used the wrong Excel chart.

Also, because the X-axis values range is too wide, I need to split the X-axis into three, to make the values more readable. Many thanks again for pointing out my newbie charting mistakes.  3 hours later… tlfong014886yst 17:21I have found the cause of the missing negative resistance portion in tracing the tunnel diode curve. I found that for the 2BS4 tunnel diode, there seems to be some oscillation in the 200mV to 270mV, 1.88mA range. Both causes are explained in the GE manual, as summarized below.

Ah supper time. See you later. Cheers.  10 hours later… Circuit fantasist3:23Very interesting… Fig. 7.1 is exactly as the picture in my movie. Do you imagine where the load line is? Or you are waiting for Tony to explain to you what the load line is:)?  1 hour later… Circuit fantasist4:43OK, I will say to you another wisdom as a reward for your curiosity. As you can see, there is no explanation about how the tunnel diode “jumps” over the negative resistance region in Fig. 7.1. (not only here but everywhere). They only say that it “jumps” but not explain how it “jumps”. Here is the geometric trick. Circuit fantasist53974:59The intersection point between two curves (the IV curve of the tunnel diode and the load line) is what is called an “operating point”…If you look at my pictures, you will see that actually, it is an intersection point of two lines. Initially, the load line moves horizontally (translates) and the line representing the static diode resistance R stays immovable. When the intersection point reaches the peak, this line begins vigorously rotating while the load line stays immovable. So, the intersection point quickly moves (slides) along the load line… this is its trajectory..  6 hours later… tlfong01488611:14@Circuitfantasist Ah, (1) Tony’s Q&A site is down (today) for indefinite time. (2) The Q&A site is only for short Q (guide line: 70 word with a picture/datasheet) and short A (Tony’s A is only 50 words!). (3) I always prefer the Agile style, muddling through, chatting over, problem based learning/solving or case study approaches. I think a college level lecture and tutorial suits me better.Also I am a picture guy. So your explanation of negative resistance jump over and load line is too abstract for me. So I prefer the following picture rather than abstract description:

USC’s Prof Khan actually shows a series of slides/steps explaining the ideas of simple load line before finally arrive at the tunnel diode load line. His explanation of the TD I-V curve using a series of pictures (it would be nice to create an animated GIF, as I suggested) is also very good. I will show you the JPG/GIFs later