Activity for Lundin
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
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A: What are these mystery components (one of wire coil, another labeled "100-10L A9")? The black one is a tantalum capacitor. There are various weird ways to mark these (because typing out `100u` instead of `100-` would be too easy...). If I'm correct in this case, I believe: - `100` stands for 100uF - `10` for 10V. - `L` is tolerance +/-10%. - From the size of it it looks like... (more) |
— | about 1 month ago |
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MAX485 transceivers breaking, Pi filter generating spikes? Problem description & speculation about causes I've having a problem with MAX485 transceivers breaking intermittently, passing our production tests but later failing. The error phenomenon is wrong signal voltage levels on the RS485 lines, as well as the transceiver failing to return the signals to... (more) |
— | about 2 months ago |
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Most reliable galvanic isolation technology for extreme EMI environments? I'm working on another project with extreme EMC requirements as per various notorious military EMC standards. Civilian product but for military use, and as such subject to the toughest levels of conducted/radiated susceptibility, 200V/m fields across an 2MHz-18GHz range, peak pulses of far higher ene... (more) |
— | 4 months ago |
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How to introduce or port my microcontroller project to MISRA C? MISRA C has become a de facto standard for all embedded systems firmware, no matter if it is safety-related or not. C comes with a lot of freedom, which makes it powerful yet dangerous. MISRA C is a safe subset of the C language, acting as a filter to block poorly-defined or otherwise dangerous parts... (more) |
— | 4 months ago |
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A: CAN BUS monitoring with a LED I've done similar things on UART lines, but for significantly lower baudrates (9600 etc) than traditionally used on most CAN buses. It's also easier to do when you have 5V guaranteed to be well-over the LED Vfwd, which the CAN lines do not necessarily live up to. For instance there are 3.3V suppl... (more) |
— | 5 months ago |
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A: Will shorting a lithium ion battery cause an explosion? It depends on how you define "battery". I guess the definition is different depending on if you are a chemist, an engineer or a consumer. When electrical engineers speak of batteries, they typically mean a battery cell - a component. Then there's the end user application with a cell + electronics emb... (more) |
— | 7 months ago |
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A: What residential wiring questions are on-topic here? The reason I left that comment is because determining the quality of a coaxial cable involves electrical engineering more so than an electrician, let alone some DIY. The rule of thumb "would you ask this to an engineer or electrician" is good. However, in this case you are unlikely to get a good ... (more) |
— | 8 months ago |
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A: Professional vs Hobbyist advice and potentially dangerous projects The main problem with a question along the lines of "how do you design a product for medical applications" is that it's way too broad. You cannot reasonably write a somewhat complete answer because it would be a very long one. The general approach of all these Q&A sites is that in case an answer ... (more) |
— | 9 months ago |
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A: Tag creation/deletion criteria Draft for a tag creation/deletion criteria A tag must fulfill all of the below requirements or it may get renamed or deleted: 1. A tag must be named appropriately, considering Tag naming guidelines. 2. A tag must be on-topic, meaning it has to be related to Electrical Engineering. 3. A tag m... (more) |
— | 9 months ago |
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A: Tag naming guidelines. Additions: - Do not use company names in tags. Questions should be about specific products, not about companies. Furthermore, silicon companies merge/split and purchase each other all the time, so company tags will quickly become outdated. For example, questions about STM32 should be tagged... (more) |
— | 9 months ago |
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Tag creation/deletion criteria Because of recent discussions regarding whether vague terms like `voltage` and `ground` should be valid tag names or not, it is clear that we have no consistent rules here. These terms are about on-topic matters, but they are vauge and ambiguous and cannot "stand alone" without other tags. In comp... (more) |
— | 9 months ago |
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A: Disabling breakpoints in real-time section of firmware Breakpoints are beyond the scope of the C language, so this is up to the specific debugger and CPU core. What you will probably have to do to block accidental breakpoints is to not provide any debug information, so that the debugger won't know which line to place a breakpoint at. How to do this is... (more) |
— | 9 months ago |
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How to deal with design review questions? A while back someone suggested that we added a section for reviews to the site - How about a new section for code reviews? From that meta thread we gathered that: - There seems to be community consensus that code review is perfectly fine and on-topic for this site, given that the topic is about mi... (more) |
— | 9 months ago |
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A: How to request a mass-change in capitalization for tags? Apart from correcting capitalization, which is a valid change, I think you are at the same time doing a lot of subjective changes to certain tags and it can get very intrusive on the site. I don't agree with a lot of the tag changes proposed here. First of all, please note that there is no criter... (more) |
— | 9 months ago |
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A: Tag naming guidelines. I agree with everything said. I didn't really consider until now that Codidact (unlike Someplace Else) supports case-sensitive tagging. So in addition, perhaps add a note regarding the following: Capitalization of scientific units and quantities/prefixes should always be in accordance with the SI ... (more) |
— | 9 months ago |
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A: Tags about quantities: should we have them? Using `voltage` as a way of saying "I'm dealing with voltage here" is pointless - most electronics questions do. I think the `voltage` vs `current` tags are however relevant in the case when you need to be more specific about which one of the two that applies. For example if you have a digital ... (more) |
— | 9 months ago |
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A: Titanic submarine control considerations Coming from a background of safety-related applications and industrial control systems, with some maritime applications experience, I could offer a few insights. These kind of game controls are literally only good for one single thing: button ruggedness. They need to withstand some pretty brutal t... (more) |
— | 10 months ago |
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A: MOSFET protection with TVS: at the source pin or at the drain pin Using a P FET for polarity protection like this means that in case you flip + and -, the gate will be inactive, meaning that GND which is now connected to drain will get disconnected - no current will flow. If you put a TVS before the MOSFET, you cancel this out. Instead the TVS will short + and -... (more) |
— | 12 months ago |
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A: Using arc trace routing instead of 45 degree trace routing The 45° routing makes it easier to route multiple parallel traces across the PCB - I would say that's the main reason why they are so popular. Whereas 90° turns of multiple parallel traces next to each other is a big no-no, since that may lead to crosstalk. And routing multiple parallel traces as arc... (more) |
— | about 1 year ago |
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A: How to perform initialization of static storage variables in embedded systems? Things happening/things we want to happen before main() is called: The code executed before `main()` is often referred to as "the C runtime (CRT)" or just "start-up code". This code is typically provided by the microcontroller-specific libraries and among other things, it initializes `.data` and `... (more) |
— | over 1 year ago |
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How to perform initialization of static storage variables in embedded systems? Whenever declaring a variable in C outside a function at file scope or when specifying it as `static`, it gets assigned a life time known as static storage duration. Meaning it will be accessible throughout the whole execution of the program. Such variables are typically allocated in one of two R... (more) |
— | over 1 year ago |
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A: A community-maintained list of abbreviations used in electrical engineering? I support this idea and think that it might fit the Papers category, although it should be allowed to have multiple users maintain and moderate it. It should be a brief glossary for a quick look-up of technical terms. Perhaps use a single word as "defining category", as seen in a dictionary and ca... (more) |
— | over 1 year ago |
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A community-maintained list of abbreviations used in electrical engineering? At Somewhere Else, we started an initiative to make a community-maintained list of abbreviations used in electrical engineering: What are abbreviations used in electrical engineering? I think it could be a valuable thing to have, although the mentioned list suffered from Q&A style and too many co... (more) |
— | over 1 year ago |
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A: Power amplifier for remote controller #1 before anything else is to do your homework. The Nordic semi web site says: "nRF24 Series Not recommended for new designs". That means forget about using this part! They are phasing it out of production and it will probably go EOL within a couple of years. Also be careful not to use some silicon v... (more) |
— | over 1 year ago |
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A: Mysterious little cases hanging on street wirings in India Based on this nerdy but seemingly trustworthy site: https://www.prc68.com/I/TelephonePoles.shtml Then I would guess these are cable TV repeaters/signal amplifiers. Classic cable TV uses copper coaxial wire, modern versions will use fibre. To deal with voltage/signal loss over distances, you n... (more) |
— | almost 2 years ago |
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What effect will extreme temperatures have on characteristic impedance of a wire? My scenario is this: radio equipment controlling an overhead crane inside a steel mill. Specifically it is used for transporting melting pots. With the current, unfortunate installation, the antenna and antenna coax cable are sitting exposed just above the melting pot where it can get many hundred de... (more) |
— | almost 2 years ago |
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How do PLCs normally measure 4-20mA current loops? I'm looking for input from anyone with insight in the PLC world. How do PLCs usually measure 4-20mA current loops? I would assume it's one of these two alternatives: - Through an external "shunt" resistor - Through internal current sense electronics My scenario is an industrial system whe... (more) |
— | about 2 years ago |
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A: Oscilloscope potentially ESD striked The usual culprits would rather be the ground clip itself or accidentally shorting something with it, more so than ESD. And if something has actually broken on the scope, I'd suspect the probe to be broken before anything else. First try to calibrate the probe by hooking the ground clip to the me... (more) |
— | about 2 years ago |
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Code formatting appears to be broken I posted a post containing C code in the Papers category here, using the ` ```c` formatting which works elsewhere on Codidact. The code does not get formatted with color coding, though it gets fixed width (courier font). This community needs to have code formatting enabled just like Software Devel... (more) |
— | about 2 years ago |
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Why should I not use dynamic memory allocation in embedded systems? I keep hearing that dynamic memory allocation on the so-called "heap" segment should not be used in microcontroller-based embedded systems. Pretty much every safety standard like for example MISRA C bans the use of it. And I don't only hear this in the context of safety-related applications, but it s... (more) |
— | about 2 years ago |
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A: Let's make all downvotes public > People will be afraid to say what they really mean. > If you don't have enough conviction in your judgement that something is wrong, then it's not worth listening to in the first place. If this discourages some borderline downvotes, OK. Downvotes aren't for when you think it might be wrong. They a... (more) |
— | about 2 years ago |
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A: Creating a FAQ: how to read a datasheet How about this: - I create a meta thread here where everyone is welcome to post contents, feedback and proposed changes. - The question of the meta thread should contain a continuously updated draft, which everyone can leave feedback to for at least a couple of weeks. - Then I create a Paper cat... (more) |
— | over 2 years ago |
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Creating a FAQ: how to read a datasheet After reading various low quality questions Someplace Else today, it (once again) occurred to me that a whole lot of people, mostly hobbyists and engineering students, have no clue how to do the most basic thing of all: how to read a datasheet. Specifically, what the various parts such as absolut... (more) |
— | over 2 years ago |
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How to protect RF switches from ESD? Assume that I have some generic antenna connector, followed by a pi-filter/50ohm impedance matching components, then a DC blocking cap (as per the RF switch recommendations) and then a RF switch for split tx/rx semiduplex transceiver, as in this schematic: antenna schematic How do I best protec... (more) |
— | over 2 years ago |
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A: Are reference requests on-topic? We haven't really addressed what SE would call "requests for external resources" here. I think it's quite clear that we aren't taking shopping recommendations, as in "where do I buy this part". Asking where to find books is similar, so I'd that say such questions are off-topic. I think it would be... (more) |
— | over 2 years ago |
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How to calculate the RC filter of a TCXO for a RFIC reference? I have a 30MHz TCXO circuit (TCXO datasheet) like this serving as local oscillator to a RFIC: TCXO filter The RFIC manufacturer recommends to "add filtering caps" for high RF output cases. That is >20dBm, after which I suppose they are concerned that the fundamental signal radiates back int... (more) |
— | over 2 years ago |
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Standardized schematic/layout file formats for PCB CAD tools? As we know there exists numerous different kinds of PCB CAD software. The big ones seem to be Eagle, KiCAD, Altium, OrCAD, Solidworks, DesignSpark and probably a few more. When it comes to mechanical PCB file formats, there is Gerber which seems to be the universal standard. But also .dxf for mech... (more) |
— | over 2 years ago |
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Location of AGC in a superheterodyne RX chain RF novice here. If using a superheterodyne receiver for the purpose of FM/FSK modulated signals, I'm wondering if the location of an optional automatic gain control (AGC) circuit is always placed on the IF amplifier in such receivers, or if there are other options? I've been reading Superhet Radio... (more) |
— | over 2 years ago |
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A: Flyback transformer with Intrinsic Safety Disclaimer: I'm not an expert of EX classification myself, but I once was project/product manager for such a project (a zone 0/20 intrinsic control system product). While I can't answer the question directly since my product contained no transformers nor flyback regulators, I can share some related e... (more) |
— | over 2 years ago |
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A: How to treat data communication questions? I think these kind of abstract/big picture data communication questions should be on-topic here. Such as the mentioned question about the OSI model. I've been actively pushing for software.codidact.com not to accept embedded systems questions and refer such questions to this site instead, so that ... (more) |
— | over 2 years ago |
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How to treat data communication questions? This question here about the OSI model was closed as off-topic. How should we treat questions about data communication? What is definitely on-topic here: - Embedded systems programming, including microcontrollers and FPGA. - Specific software or hardware questions about industry standard buses l... (more) |
— | over 2 years ago |
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A: How can we grow this community? After reading the suggestion about conferences, I came up with a loose brainstorming idea... What draws engineers to fairs/conferences (apart from free lunch)? Most definitely technical speeches/slide shows about a certain technical topic. This is well-known: try to host some embedded systems fair wi... (more) |
— | over 2 years ago |
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Do we need tags for supply voltages? Someone just created the tags 208VAC and 230VAC. If think we need to create a policy about tag usage related to supply voltages. Clearly, stating the supply voltage is highly relevant information in most questions. However, stating it in the form of a tag may not be ideal. - Should we have tags... (more) |
— | over 2 years ago |
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A: Asynchronous connection question Assuming you speak of UART, then the receiver must be told in advance the number of data bits, the number of parity bits and the number of stop bits. The start bit is a logic zero (low) and the stop bit(s) are logic ones (high), which is also the idle state. The data bit stream itself isn't asynch... (more) |
— | over 2 years ago |
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A: React feature guidelines? Example of answers that should be classified as Dangerous: - "Do it yourself" Q&A where someone is fiddling around with 230VAC electronics or other such potentially lethal power sources without having much of a clue of what they are doing. - Potential fire hazards, such as modifying consumer elec... (more) |
— | over 2 years ago |
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Most correct term for radio switching noise? I'm wondering what's the most correct term (if any) to use for "switching noise" of a radio transceiver? By that I mean the spikes that originate from turning the power amp on/off while switching between sender and receiver. Apart from switch noise (which is easy to confuse with switching regulato... (more) |
— | over 2 years ago |
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React feature guidelines? I think we should try to come up with some consensus regarding how to use the new reactions feature, more specifically the "outdated" and "dangerous" options. Which kind of posts should these be used on? Otherwise, I can see how these quickly turn subjective without some community consensus or gui... (more) |
— | over 2 years ago |
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CAN "split" pin, bus termination and common mode stabilization Modern CAN transceivers like MCP2561FD that support CAN FD with high baudrates come with an optional feature called SPLIT, which is to my understanding a reference voltage output pin used to give a common mode stabilization and thereby reduce radiated emissions. It gives out 0.5Vdd so that would be t... (more) |
— | over 2 years ago |
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A: Select resistor for a diode You start by checking the forward voltage and rated current for the LED. 20mA is the usual industry standard for regular LEDs and the forward voltage will be specified for that rated current. In this case the datasheet says VF = 2.0V typical @ 20mA. So now we know the current and the voltage wi... (more) |
— | over 2 years ago |
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Thermal relief for through-hole on multi-layer PCB When using through-hole ("THR") connectors on a multi-layer PCB, I frequently notice problems with the ground pins, when these are connected to the ground plane(s) through various "thermal relief" layouts. When this happens, the reflow soldering job becomes mediocre and hand soldering is nearly impos... (more) |
— | over 2 years ago |