Teacher (Maths, Physics, Energy and Experimental Lab courses), Lecturer, Author, lapsed high energy theorist
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nprofile1qqsx5tstq2cweqsrw8kj6zcg5k0yyx7vdkhwvgurqqurkrdn2w5k94qpz3mhxue69uhhyetvv9ujuerpd46hxtnfduqs6amnwvaz7tmwdaejumr0ds4mnup8
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2025-06-20T12:37:47Z Event JSON
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"content": "{\"name\":\"Alexander Knochel\",\"about\":\"Teacher (Maths, Physics, Energy and Experimental Lab courses), Lecturer, Author, lapsed high energy theorist\\nSignature signature (+,-,-,-)\\n... Ham Radio \u0026 electronics, Physics, Music, Math, Energy, ecomodernist tendencies\\nJ.S. Bach \u0026 Metal stan account, vegetarian Pfälzer,\\nCall DK3HD, find me on 20\u002640m and our local repeaters ...\\nsomewhere near Heidelberg, Germany\\nwww.FACW.org DARC A20\\nwww.ukw-tagung.org\",\"website\":\"https://astrodon.social/@quantensalat\",\"picture\":\"https://media.astrodon.social/accounts/avatars/109/305/225/464/946/153/original/0137b330dfe5bd75.jpg\",\"banner\":\"https://media.astrodon.social/accounts/headers/109/305/225/464/946/153/original/f055d86879fd8dab.jpg\",\"nip05\":\"[email protected] \"}" ,
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Last Notes npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Now that's an amphora I can get behind, literally. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Fun fact: if the vertical axis is interpreted as time and the horizontal axis as a spatial direction, this is an actual calculation in relativity theory: the zero stands for the time that passes for a hypothetical observer moving at the speed of light. More precisely, the distance covered by a moving object in minkowski spacetime corresponds to the proper time as measured by a moving observer. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Ich bin kein Synästhet, ich bin einfach nur alt genug um viele Telefonzellen verwendet zu haben ^^ npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel ist es komisch dass ich dieses Bild riechen kann? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel This is in jest,but I just googled when piano rolls were invented, and it was like 1880 or so ;) npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I love the 60s classics. Especially the 1860s ;-) npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I just had to check and, lol npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I'll explain in ainute why this indeed precise even if it doesn't sound so at first npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Let me start this way: npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel So today is the birthday of Amalie Emmy Noether. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Noone ANTicipated that development npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel But in seriousness, how does the biasing work in the output stage? Is it a JFET that self biases? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I hope this wasn't the amplifier module hrht npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Using the latest Linux version of wsjt-x with a Xiegu X6100 with digital modes, and it only uses USB sound in for the first transmit cycle, during the next, it takes sound from the hand held mic. I tried a firmware update but it didn't seem to help. Help, I don't want to whistle the FT8 myself! npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Today was one of those physics lessons which completely escalated in a fun and spontaneous way when students demanded (at the end of a long arduous unit on induction and electric/magnetic fields) that they want to 'transmit something' npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Is it an accurate picture to have the language of the people descended from some pre existing lofty high language? That sounds partly backwards somehow npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I'll be looking forward to the tests! npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel A 12 V hair dryer is a bit scary tbh npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Hey, so when do you expect to have a board finished for tests? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Very nice thanks for sharing your measurements and the video. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel rewatching the rest now npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel out of scientific curiosity apropos the.previoua discussion, can you measure L of one primary half turn with a shorted secondary? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Fortunately, one can murder a whole bucket full of those transistors before you get to the price tag of one of those NXP Ldmos things ;) npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel If you tell me that these constructions as pictured achieve that well, I'll be happy... npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Sorry if my wording was confusing, I meant that if there is no great coupling between the two halves of the output transformer, half of the three windings always act as a large *series inductor* at the output when the corresponding transistor is open. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I'm not sure about rail (because I'm talking about the secondary side) but yes when one mosfet is high impedance and coupling between the two eyes of the transformer is not great, one of the secondaries looks like a choke to me, and that seems bad. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I'm worried about the secondary imductance on that side! npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I realize there is something absolutely fundamental I don't understand about those binocular RF amplifier transformers as they are realized in many designs: each transistor often seems to drive only the copper tube in one of the holes (see my "drawing"), while the secondary windings go through both holes. Do we assume that one transistor firing on one side magnetizes both sides? That seems a bit unlikely, and if not, the other, idling side acts like a very large series choke at the output. How is that supposed to produce a proper 50 Ohm output? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I cannot confirm his observation that the IRF530 suffer from thermal runaway at higher supply voltages. I had this problem massively with the 540, but the 530 runs reliably for me w/ 30V and relatively large quiescent currents of >~100mA per side, even FT8 npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel What is the intended supply voltage for 70W? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I too tied my brain into knots about those impedance ratios. Especially since each transistor only works for roughly half a period, I ended up deciding that i'd ignore the other transistor and simply consider the turns ratio one transistor sees looking at the load (*). But I don't quite follow how you go from 50 to 0.6, that looks like you take the 1:9 ratio squared again. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I believe in axial tilt. I am told he's the reason for the season ;) npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I get it but I didn't find a silly tongue twister which reflected this fact accurately :) npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel so, are you saying she is not filled with guilt after gifting a machine with quality built for the quilting guild? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel ever since I've seen microwave PCBs I'm convinced it is black magic, pure and simple. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel We need a word for that very deep uncanny nausea one feels watching #AI drawn images. You know exactly what I mean, right? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Ticks against Tetanus npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel No shit, Like when Captain Picard asks Crusher and Data to save the infected alien planet without violating the prime directive, and they're like: we'll simply use the vector and remodulate the genetic matrix of the parasite to align with the species immune response, and he'll be like, make it so! npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I either want Brie or Entertainment, not both. This is unacceptable. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Decades of Nazi documentaries on the Discovery and History channel, but the most important lesson wasn't learned. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Good morning! npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel This is me, is there a modern name for it? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel My problem is that the Micro:Bit serial output does not seem to sink enough current to pull the LoRa Board RX down to 0V. The same module works when driven by a Raspberry Pico (shown on oscilloscope). Does the micro:bit have such a high output impedance, or the Seeed Wio E5 such small pullup resistors? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Oh great,debugging, but also with hardware. Thank the maker for RTL SDR so at least I know if and where the LoRa TX TXes npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Great success! npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel A first and second look suggests that the goal is reachable - I've already tested the serial send functions in MakeCode, and one can send serial data to the big 0,1,2 pins. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel All right. My #stem #teaching challenge for this week is to develop a way how 9th graders can program a BBC Micro:Bit with Block Code to send data via LoRaWAN in a way that is clear and simple enough for the students to do in two days of workshop. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Do you know by heart if full speed vara has a multi tone modulation? npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel ..--.. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel I'm using Vara but I couldn't tell you if it was using more than one frequency at the same time in principle. That being said, listening to my Vara transmissions, they very much sound like single tone. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel --.- --- .----. ..--.. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel - .- .... .--. .- --. .... - .- .... -... . .----. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel --.- .- .--. .-.. .- .----. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel CQ on all subspace frequencies npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel #Grenzkontrollen npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel If you scream in all caps on mastodon, people will just ignore or mute it because there's enough of that elsewhere npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel physical:e 1:1 npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Funny #hamradio scene in Jurassic World: Fallen Kingdom. npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel It probably contains an Americium source, like a fancy old school smoke detector npub1dghqkq4sajpqxu0d959s3fv7ggducmdwuc3cxqpc8vxmx5afvt2qh6gkrs Alexander Knochel Is that a ram with a power supply for durability/permanence?
