https://community.element14.com/members-area/A place for members to hang out!en-USTelligent Community 12https://community.element14.com/members-area/support/f/forum/56964/was-there-a-problem-with-my-image/235800Mon, 25 May 2026 04:04:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:97211440-a86f-4e82-ad6c-76f1194d3e10embeddedguyDudley Thanks. sure.! It's fine.https://community.element14.com/members-area/f/forum/56973/introduction/235796Sun, 24 May 2026 19:24:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:42511dd5-2506-4c3f-85d1-dde04f589577colporteurThere's been a few post on SPI and IC2. Clem did a setup How Far Can I2C Go? -- Episode 666 to see how far I2C can travel.https://community.element14.com/members-area/personalblogs/b/michael-kellett-s-blog/posts/two-pre-amplifiers-and-a-power-amplifierSun, 24 May 2026 15:01:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:945341cd-3352-4b7a-aa4c-b84d618ff657michaelkellettshabaz has been working on a Simple DCR (Direct Conversion Receiver) and an intercom which both need pre-amplifiers and small power amplifiers. To keep within the spirit of the original DCR project he wants to use discrete component designs with no ICs. I made some suggestions about the design of the audio sub components and when Shabaz had some board made he was kind enough to send not just some boards but most of the components to fit on them. You can read about the project here: https://community.element14.com/technologies/open-source-hardware/b/blog/posts/simple-dcr-direct-conversion-receiver-part-2-common-emitter-amplifier?CommentId=0f0868bb-7391-4262-9d02-b9f24ed4e146 This blog is about building the two pre-amp designs and the power amplifier and testing them. The plan is that these amplifiers shall work from a 9V battery or a DC power source and I have taken that to mean that they must work well with 8-9V and to some extent with 6 - 10V. The kit of parts that Shabaz sent to me: The three amplifier boards The K1 Pre-amp The K1 pre-amp is based on the original in the DCR project. It's a very simple design but has low gain and quite high distortion. I measured it using the HP654A Test Oscillator which I have had for some time. It's a nice LF oscillator with good amplitude flatness and a 99dB range output attenuator with an additional +/- 1dB fine control of the oscillator output amplitude. The huge attenuator range is great for measuring amplifiers. The downside of the 654A is its rather high distortion (approx 1% at 1kHz and worse above 1MHz). One day I might replace some of its insides (but not until all the magic smoke of the original parts is used up). You can still find the service manual on the web. I measured the amplifier outputs with the B&K 2426 auto-ranging voltmeter. It's a recent acquisition from an auction and cost about £55. It needed a little attention to its switch contacts but is working nicely now. The other tool used was the Picscope 6424E which I Road Tested some time ago. It's been replaced as my everyday scope by the R&S MXO4 but Pico keep poking me about their Picoscope7 software and I thought I should give it an outing. The picture actually shows the K2 pre-amp but the tests set up was mostly the same. (I do wish that people wouldn't deface beautiful instruments with silly calibration stickers - this one is so well stuck that I think removing it will bring the lettering off too.) The K1 Pre_Amplifier circuit I built the pre_amplifier exactly as shown on the ciruit diagram and it worked almost as intended except that the low frequency -3dB cut off was at 475Hz. This was because C4 is too small. The AC impedance of the emitter circuit is set by R4 in series with C4 (R5 impedance should be a lot higher at operating frequencies than C4 impedance so we can ignore it.) There are three separate RC combinations that set the low frequency cut off of this circuit (C1:R1//R2, C4:R4, C2: load resistance). The cut off frequency of a series RC network is 1 / 2.pi.R.C and if all three are in play we should set each to cut off at about 1/2 of the required lower operating frequency, which is about 200Hz. So the ideal value for C4 = 1/(2.pi.100.47) = 33uF. I used 47uF. On the same basis C1 should be 65nF and C2 should be 80nF (with a 20k load as fitted to the power amplifier). The load resistance might be a lot lower than 20k and the 4.7uF cap for C2 will be OK with a load of less than 1k. Changing C4 to 47uF changed the LF cut off to 196Hz, which is a little higher than I expected but not enough to worry about. Later on I changed C1 to 220nF and the LF cutoff moved to 68Hz. The K1 pre-amp has a measured gain of 27.6dB. For detailed performance of both pre-amps see the "Pre-amps performance data " section below. K1 pre-amp Distortion I used the Picoscope to measure the distortion. The K1 distortion is so bad that the HP654A was quite good enough as the signal generator. All measurements were made at 1kHz with an 8V supply. Distortion performance of K1 pre-amp 1V p-p output Distortion performance of K1 pre-amp 2V p-p output The distortion performance is pretty grim - 24.36dB is about 6%. The K2 Pre-amp The K2 pre-amp is based on the DC coupled pair pre-amp design which was popular in the mid 1970s fin HiFi magnetic pickup pre-amplifiers (eg Quad 33, Lustraphone LP100). This design has an emitter follower buffer on the output to enable it to drive low impedance loads while operating from quite a low supply voltage. The K2 design is a near clone of the LP100 but works with a 6 - 10V supply rather than 30V. The K2 pre-amp works much better than the K1 - much higher gain and much lower distortion - the price paid is that the supply working range is less good - it won't work at all with a 4V supply and barely works with 5V. It might be possible to optimise the DC biasing to improve this. The HP signal generator is not anywhere near good enough to measure the distortion of the K2 pre-amp so I used a Neutrik A1 Audio Tester as the signal generator. It can measure distortion as well but I stuck with the Picoscope for a more direct comparison with the K1. Neutrik A1 Audio Tester, 1kHz distortion approx 0.004%.(-88dB) K1 pre-amp distortion 2.35Vp-p out, 1kHz, 8V supply = -65.6dB = 0.05% Pre-amps Performance Data Pre-amps - summary The K2 pre-amp uses a few more parts but massively out-performs the K1 in all respects other than low voltage working. If that's a problem the design could be tweaked a little to optimise the DC bias of the K2 for a different voltage range. The K1 Power Amplifier In Simple DCR: Assembling a 7 MHz (40m) Direct Conversion Radio Receiver – Part 1 Shabaz explains his problems with the simple transformer coupled power amp in the original DCR design. He could only get about 830mV pk-pk into an 8R load which is a about 10mW. A transformer-less design should be able to manage about 6V p- p with an 8V supply which is about 560mW into 8R. My first attempt was a simple 4 transistor design based on a very old (1969) Mullard book. I couldn't get it to work on strip board although it looked OK in simulation. I decided to start again with a design which is the basis of almost every HiFi amplifier made in the 1970s and 80s. Long tailed pair input, single inverting amplifier and level shifter with current source load and emitter follower type output. The K1 power amplifier In HiFi applications the output transistors were often darlingtons or other multi-transistor composites and the load was frequently DC coupled, requiring the use of dual +/- power supplies. Once I had built the amplifier on Shabaz's board it sort of worked but not at all well. My strip board version worked fine. I wasted quite a lot of time trying to work out the problem during which I had lots of issues with the Picoscope triggering badly. Eventually I gave up on it and switched to the R&S MSO4 and found the issue in about 2 minutes (scope warm up time + 10 seconds) - the amplifier was oscillating at about 100MHz which caused lots of distortion and excess current drain - and of course was the reason for the bad triggering on the Picoscope. I checked it again and realised that I had, at some time earlier, engaged a digital lows pass filter at 20kHz on Picscope Channel 1 - this rendered the 100MHz oscillation invisible but the Picoscope doesn't have a big pre-digital filter overload margin which is why the signals looked clean but distorted. (To be fair the Pico was flashing up an overload warning which I hadn't noticed - so don't take any of this as a Picoscope fault - it was just me not being used to the PicoScope7 software.) The solution to the oscillation was a 120pF capacitor between Q3 base and emitter. Amps with this basic topology very often need a cap here and I should have put it on the design with a zero value. I can only assume that my strip board version had enough stray capacity in the right place. Once this was resolved I was able to do some measuring. The distortion of the power amplifier is a bit too low to be measured on a scope so I used the Neutrik A1 to measure distortion but an HP8904A signal generator because it has much easier level adjustment and it hadn't had an outing for a while. It has a nice new blue display because the old grey one had almost no contrast any more. HP8904A signal generator with replacement LCD display With an 8V supply the best output power I could get just before clipping was about 1.357V into 8R = 230mW I was able to improve this a little by replacing the output capacitor with a rather large low ESR type. A quick glance at the ciruit shows that R1 and R2, are going to waste a lot of power, but if they are reduced there will be excessive quiescent current though Q2 and Q4. My solution was to short out one of the diodes (D2) and short out R1 and R2. The distortion at 1V RMS out (8V supply 1kHz) was 0.09% and after D2 was shorted rose to 0.19%. The modification actually reduces the total amplifier quiescent current from 10mA to 6mA. But now the amplifier can manage 430mW with an 8V supply at 0.5% distortion or 585mW with a 9V supply. The distortion added by shorting one of the diodes is crossover distortion because there is a small period where one output transistor turns off but the other hasn't turned on. You can see this on a scope if you look hard: single diode X over distortion same signal and same cursors to put the crossover step into scale approx 1V RMS output with spectrum K1 Power amp summary The K1 power amplifier works very well once the 120pF capacitor has been added. The amplifier power output can be significantly increased (and Iq decreased) by removing D2 and R1 and R2 (by shorting them out)). The power output at 8V is about 1.1dB less than the target when the modifications have been made (3.8dB without). The distortion (modded or not) is very low, < 0.2% at 125mW output.audioanalog_electronicshifihttps://community.element14.com/members-area/f/forum/56914/we-have-made-changes-to-the-element14-community-homepage/235785Sat, 23 May 2026 17:11:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:b05e17a9-6f6e-4937-af44-deba2f6b6759beacon_dave[quote userid="17018" url="~/members-area/f/forum/56914/we-have-made-changes-to-the-element14-community-homepage/235784"]I'm estimating 14 years for my next level, based on past performance[/quote] It feels as if it's getting harder to collect points now. It would perhaps be interesting to see a graph showing the points accumulated at level changes & each year of participation, against the dates, to see how past participation performance has varied over the years.https://community.element14.com/members-area/f/forum/56914/we-have-made-changes-to-the-element14-community-homepage/235784Sat, 23 May 2026 16:28:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:d875d5bc-9f5c-423b-b13e-3d711ee2da68Jan Cumps[quote userid="35177" url="~/members-area/f/forum/56914/we-have-made-changes-to-the-element14-community-homepage/235610"]I stopped looking at my points and how many I needed for the next level, a long time ago because they were moving so slowly. [/quote] I'm estimating 14 years for my next level, based on past performancehttps://community.element14.com/members-area/f/forum/56959/are-you-using-ai/235775Sat, 23 May 2026 08:13:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:53aff794-e55e-46f8-8887-6f0967ee2ae8acdc90in the past when working on a old domestic device if its audio there is usually someone that has a manual. if its industrial if the owner doesnt have a manual, then sit down and nut out how it works then check sensors or relays and if boards have capacitors that have dried up then if any moving cables that could have broken. After that make a flow chart of eventshttps://community.element14.com/members-area/f/forum/56944/what-is-your-favorite-road-test-on-element14/235773Sat, 23 May 2026 07:45:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:0cb609fb-c7a3-424f-9fde-d7364a3a3361dougwI did both a series of blogs and summarized them in a road test.https://community.element14.com/members-area/f/forum/56959/are-you-using-ai/235772Sat, 23 May 2026 07:40:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:82f5fad5-0d35-40cc-940f-9a1533b6f26bdougwAI can do lots of things but they don't shorten design time or improve designs - yet. AI can select components, but it takes a lot of work to get it to select an optimal component and then how can it prove it did a good job without showing you hundreds of datasheets. Sure it can organize the data sheets, with enough coaching, but a parametric search engine is going to compete favorably with AI at this task. AI can generate a netlist, but how can it prove it is a good design? Do you have to translate the net list to a schematic and PCB layout and build the card and test it to know if it was hallucinating? Verifying the design from a netlist introduces far more problems than it solves. I haven't seen anyone show that AI is good at designing circuits. Presumably it will happen at some point.https://community.element14.com/members-area/f/forum/56973/introduction/235766Sat, 23 May 2026 04:17:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:90fcb018-78e5-4703-b962-cca685b257a2DipeshkachhiThankshttps://community.element14.com/members-area/f/forum/56973/introduction/235765Sat, 23 May 2026 04:17:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:d2b1fcc3-162e-4153-b47b-d520143d4851DipeshkachhiThankshttps://community.element14.com/members-area/f/forum/56973/introduction/235764Sat, 23 May 2026 02:49:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:fdbd4368-730e-4766-8e46-ad998b1e0680DipeshkachhiThankshttps://community.element14.com/members-area/f/forum/56973/introduction/235763Sat, 23 May 2026 02:49:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:a4063a4c-22a2-45ca-ac5a-b44d1f6c4a62DipeshkachhiYeahhttps://community.element14.com/members-area/f/forum/56973/introduction/235762Sat, 23 May 2026 02:48:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:d7cfef19-8e6b-46f6-8f0d-980abbd9a3dbDipeshkachhiYeah I have many , but I will be graceful if i could help anyone.https://community.element14.com/members-area/f/forum/56959/are-you-using-ai/235760Sat, 23 May 2026 00:06:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:822f8e71-f3e4-4919-845b-cfcfb8c4e406SensoredHacker0lol sensored the title of a story about a big white whale.https://community.element14.com/members-area/f/forum/56959/are-you-using-ai/235759Sat, 23 May 2026 00:02:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:1e1c7664-c00d-42df-b2d1-96a14fd6e254SensoredHacker0Aw man, theres so many things I would love to see AI trained on. Id like to say, hey AI, read my PLC program, and tell me where I have 36 contiguous registers free. or, optimize this ladder logic. or find and clean up unused registers. or read this engineering manual, protocol guide, or spec sheet, and return functions, values, whatever data, that pertains to the specific model hardware we use. Getting AI to read tech documents is nearly impossible to begin with, every OEM has sort of random formatting. A common theme is that every model in a product line is in one document. so then youre reading that document looking for functions pertaining to your specific hardware, and you have to carefully parse which functions track to which units, which makes designs and implementations hard. My main goal is process automation to maximize production, though for the last 9 months Ive been on sensors and logging of every type of thing.. while systems to do certain processes exist in the generic sense, even if IEC61131-3 exists, it doesnt mean you can utilize it in a practical way. PLCs have been out for decades, and many, new or old run the same code that ran 40 years ago. But their niche, regarded as such, theyve existed for so long, yet the documentation is persistently awful. PLC design patterns. Theyre not PCs, even if they operate similar to PCs. I have never been able to get good design tips out of AI for PLC systems. so AI wont / cant read the published docs, and to be fair, many of the published docs are garbage. theres many possible solutions, and opportunites for AI to succeed, but its all dependent on specific OEMs. Theres other things that annoy me about AI, on the brink of being useful, but not there yet. Take Andriod studio for example. Andriod Studio now has integrated gemini AI. But the integrated AI doesnt know anything about andriod studio. its a generic code bot. Theres no features to it. The thing could do all sort of amazing operations, but its all generic. Hey AI, teach me how to use Android studio... then it could highlight menus, or help navigate the complex code it generates. but its not really aware of the platform it is in, which is infuriating, because both are Google products. I was using confluence today, and its the same sort of thing. I wrote an article on how to do a process. (Ive wrote many) did I write it in my personal articles, or the company articles? I'm not sure. Ask ROVO. Rovo tells me how to search. user = currentUser() ok thats cool, but it doesn't search keywords, or ignore case, or basic text search, so it has AI, but basic functionality is missing. I wrote about a bug in Rpiboot, I know the keywords, but can't recall the exact title, or project that the paragraph was published in. We have this AI with access to all our company documents, and it cant do a proper search. I feel like its that way with many AI implementations, there's the low hanging fruit, that makes it interesting, but then where it could be legitimately useful, those features are not implemented, or may even be missing, because everyone assumes the AI implementation can do anything. it goes on and on like that. Part of it is AI, but part of it is the system integrator swapping out basic functionality for AI. For AI its context, but for a human user, its a half baked product. Theres an example I like: you ask an AI did Captain Ahab die in Moby ***? The current NLP paradigm is something like read the entire book into memory and parse it. which is horrendously inefficient. The answer, is on page 1. but thats not a smart systems approach. What could be done, is the book moby *** is a Canonical Novel. Books of this genre follow the pattern of having a beginning, middle and end, going from character intro, plot development, Climax, conclusion. being a lazy kid in high school, who doesn't want to read the whole book, but knowing the type of book, we could assert, that if moby *** is 200 pages, that the climatic section of that book would be around pages 180, and read that. but this is an intelligence assertion against a known structure. That's what I dont see in AI. Maybe its there. I, the user of AI can not impart any of my knowledge onto the AI. Instead I have to repeatedly craft linguistically detailed instructions to get results. which from an automation perspective is pretty insane. You can of course see similar attempts at max lazy being deployed in AI. its just not smart about it. you upload a 2000 page pdf, and say hey parse this. AI will read the first few pages and try to answer your questions. Being sentient, you notice this. so you break a 2000 page document into 100 distinct PDFs. suddenly the AI can return better results. But again, its all things like tricks to leverage the system to compensate for a general lack of intelligent design. if the AI could find chapter 37, and read the 3 pages there, and not be confused or miss lead by sparse parsing. then maybe it could be more useful.https://community.element14.com/members-area/f/forum/56973/introduction/235758Fri, 22 May 2026 22:31:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:e10e03cd-acb8-4c2c-b53a-014f3f5aca9ckmikemooWelcome to the community.https://community.element14.com/members-area/f/forum/56973/introduction/235756Fri, 22 May 2026 19:16:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:61bfe872-4aef-424b-8ba6-407de33da3d0acdc90Welcome, Do you have a project in mind or are you here to help everyonehttps://community.element14.com/members-area/f/forum/56961/top-tech-voices-podcast-s2-e6-smart-cities-urban-tech/235749Fri, 22 May 2026 13:29:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:36097579-97a5-4d13-8800-ce2930754517beacon_daveInteresting the views on architecture bringing more nature back into the urban environment, however this appears to be the exact opposite of what is currently happening here. The architects / urban planners if anything are increasing the density of the built environment at every opportunity. A lower density house with garden space is more likely to be refused a planning application than a higher density block of flats. Greenbelt land is being built upon at an increasing rate. Allocating / retaining space for nature is unlikely to provide the same income streams as high-density accommodation. Perhaps the only realistic chance of incorporating nature into the new builds and public spaces now would be rooftop / vertical gardens and perhaps have skywalks between them. Also interesting the views on using nature to drive reactive systems, but given that architects currently appear to struggle to design new energy efficient homes with heating/cooling systems that just work, then this sounds rather ambitious and fraught with problems down the line. In the 80's architects experimented with mechanical iris shutters on the likes of the Institut du Monde Arabe building in Paris, to create a kinetic façade to control light entering the building https://www.youtube.com/watch?v=gq6x3x3YXFY very nice, both aesthetic and functional but over time it stopped working resulting in expensive repairs https://www.youtube.com/watch?v=kEI4wml0F78 which raises the question of how today's world of built in obsolescence would impact reactive systems. "Your house isn't compatible with the latest upgrade, you'll need a new one..." At least they had the foresight to allow the reactive panel to be accessed from the inside for ease of repair/replacement. As for making the urban environment more resilient to climate change, then architects don't appear to have a handle yet on the current climate judging by the amount of damage every year caused by wind, rain and flooding. It appears that around two-thirds of homes in the UK fail to meet the current efficiency standards with only around two-fifths of new builds meeting current standards. Perhaps better monitoring of actual performance as opposed to relying upon predicted performance, could help steer design choices.