Activity for Lundinâ€
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Comment | Post #291238 |
Ok so maybe the inductor is just meant to be (part of) a filter. Then the IC could very well be a linear regulator or just a transistor. (more) |
— | about 1 month ago |
| Comment | Post #291238 |
I'm guessing the connector. And since it is a hand-held device running on batteries, voltage out to power something? Or does it use rechargeable batteries and that's voltage in? (more) |
— | about 1 month ago |
| Comment | Post #291239 |
"The component to the left of the inductor in second picture looks to be a diode. It only has two terminals. The stripe at one end probably marks the cathode."
Nope, tantalum caps, the stripe marks + since they have polarity. And they like to explode :) (more) |
— | about 1 month ago |
| Comment | Post #291240 |
@#52935 I found some boost converters for 3.3V by the semi-obscure brand Torex that might fit the bill, but I couldn't find any matching documentation about part markings. There's lots of linear regulators with markings 331 but that doesn't explain the inductor. Unless it is double-sided mounting an ... (more) |
— | about 1 month ago |
| Comment | Post #291110 |
That shouldn't be a problem for a PCB sitting in an enclosure, given that the usual anti-ESD measures were implemented.
Electronics love dry places. The more obvious issue that dry tends to go hand in hand with warm, and that's where all manner of issues can pop up. (more) |
— | about 1 month ago |
| Comment | Post #291085 |
I have the transceivers failing during production and I doubt the cause is ESD. I suppose hot-plugging during testing could be a culprit, but then the type of connectors used means the ground is always there before voltages. (more) |
— | about 2 months ago |
| Comment | Post #291082 |
I guess the TVS values were picked because we already have the same ones elsewhere on the BoM protecting 24V on/off and the like. That and taking a bit of the blow in case someone shorts the supply against data lines. We have already considered adding TVS suitable for RS-485, I noticed there are some... (more) |
— | about 2 months ago |
| Comment | Post #291082 |
Oops yes this is a typo. Since the design is propriety, I cannot share it as-is, so I just quickly redrew the relevant parts in an online schematic program. (more) |
— | about 2 months ago |
| Comment | Post #291080 |
@#53661 It can be hot-plugged, yeah, but I don't see it related to the failures. The PCB ground will be sitting close to the chassis ground potential - it will be grounded to chassis from where the PCB is connected, as well as at a few other places where shielded connectors are attached to the chassi... (more) |
— | about 2 months ago |
| Comment | Post #290874 |
The slightest scratch will mean that the solder mask is leaking however. Solder mask is literally what it says: a means for preventing solder to end up on top layer traces. Using it for anything else (including isolation) is questionable practice. Anyway, the standard practice for anything in tough e... (more) |
— | 2 months ago |
| Comment | Post #290874 |
How would the signals get to the SMD connector without vias? Some sort of blind vias? Are they waterproof and who says so? Anyway, to be honest this is such a bad idea from the start. Not just because of water, but because of salt, galvanization and probably a bunch of other problems too. Separate th... (more) |
— | 2 months ago |
| Comment | Post #290774 |
I still think this question would be more suitable for Power Users, where computer hardware questions are [explicitly on-topic](https://powerusers.codidact.com/help/faq), whereas here on EE the question is [explicitly off-topic](https://electrical.codidact.com/help/topics) since it is still about "hi... (more) |
— | 3 months ago |
| Comment | Post #290541 |
@#52935 Regarding availability I don't think you can look at the Covid component crisis, since pretty much every silicon vendor's logistics chains were broken. I couldn't get plain schottky diodes of any brand with less than 30 weeks... same deal with any Cortex M of pretty much any brand. ST and Inf... (more) |
— | 4 months ago |
| Comment | Post #290541 |
@#52935 I will use a modern standard transceiver like MCP2562FD which has great voltage tolerances and good ESD protection. Then TVS, common mode EMI filter etc etc on top. Not worried about protecting the actual bus, we've passed similar nasty EMC testing before when using RS485, but we didn't use g... (more) |
— | 4 months ago |
| Comment | Post #290541 |
Thanks for your reply! Though I'm not following your concerns about CAN. The isolator, no matter type, will have to be placed between the MCU and the transceiver ("CMOS levels"). The Tx and Rx signals there are not bidirectional. The isolator I linked and intend to use is 2 channel, so there's one ch... (more) |
— | 4 months ago |
| Comment | Post #290533 |
@#52987 Both primary and secondary will be supplied with old school LDOs and we'll also encapsulate the whole PCB with screens. Decoupling caps on all supply pins naturally. I don't think there's a risk that the supply traces etc pick up substantial currents from radiated EMI that way? Maybe it's wis... (more) |
— | 4 months ago |
| Comment | Post #290423 |
Either solution sounds over-engineered IMO. If you have a CAN bus, you have a MCU, so why not use the MCU? (more) |
— | 5 months ago |
| Comment | Post #290231 |
Also this could mean anything. We have high voltage regulation (>1000VAC, >1500VDC) , we have "low" voltage regulation (50-1000VAC, ~75-1500VDC) and "extra low" voltage regulation (<50VAC, < ~75VDC). These categories can in turn be divided into many sub-categories: isolated regulators, transformers,... (more) |
— | 6 months ago |
| Comment | Post #286035 |
I think I've seen this app note before, I use the very Silabs parts that they use as example. But most of it is generic ESD and the figure 19 didn't really bring anything new other than "take care about the parasitics of the selected TVS diode", which was already mentioned in the question here. Figur... (more) |
— | 7 months ago |
| Comment | Post #289688 |
Which part is the Darlington, more specifically? One of the classic ULNs I take it? These are notoriously brittle and shouldn't be used in industrial applications. Consider some "smart" MOSFET driver instead, with plenty of built-in protection. (more) |
— | 8 months ago |
| Comment | Post #289574 |
And well, trouble-shooting PSUs on the product level is probably off-topic here. We'd expect questions to rather be about how to trouble-shoot them on the component level. Rectifier bridges, transformers, regulators, isolation, filters etc etc. (more) |
— | 8 months ago |
| Comment | Post #289574 |
You won't ever get to the bottom of the cause of the "spark noise" unless you dissect the PSU, do some light reverse-engineering and see what may be the cause. However, please note that disassembling these can be dangerous even with power disconnected since the internal caps can hold high loads for q... (more) |
— | 8 months ago |
| Comment | Post #289423 |
I deliberately picked PID because it has only one sensible definition in the context of Electrical Engineering. Process ID is (arguably) not a term used in EE, so therefore the term which _is_ used, established and well-known too, should be the one that get the tag as well as the abbreviation. Otherw... (more) |
— | 9 months ago |
| Comment | Post #289348 |
@#52991 Ok so I tried to compile a draft for some sort of general policy here: [Tag creation/deletion crieria](https://electrical.codidact.com/posts/289416). And yeah this might mean that tags such as `voltage` are free to delete. Any feedback is appreciated. (more) |
— | 9 months ago |
| Comment | Post #289348 |
@#52991 But if we look at more specific tags, you also propose to delete `PTC`, which stands for positive temperature coefficient. This term is (almost?) exclusively used in the context of thermistors, at least as far as I know. Therefore `PTC` is a clarification of a question tagged `thermistor` in ... (more) |
— | 9 months ago |
| Comment | Post #289348 |
But also **we should not make it harder to change tags than to invent them**. If we allow everyone and their mother to create tags, which is usually the case, I don't think we can regard tags as something "holy" as on SE but let trusted users/moderators change them without too much meta debating. I t... (more) |
— | 9 months ago |
| Comment | Post #289348 |
I think we have to live with on-topic tags that hold no meaning of their own and this is how SE always worked too. (more) |
— | 9 months ago |
| Comment | Post #289348 |
I think the main issue here is that there's no clear consensus regarding tags that aren't meaningful stand-alone but otherwise clearly on-topic. As I already tried to explain here https://electrical.codidact.com/posts/289217/289280#answer-289280, such tags might give the post a meaning in combination... (more) |
— | 9 months ago |
| Comment | Post #289392 |
@#8046 Hmm I had not realized there were differently formatted tags at Proposals :) I can see it now that you told me, but maybe the problem there is the opposite - too subtle. (more) |
— | 9 months ago |
| Comment | Post #289392 |
@#8046 Different colors might be interesting, as long as it doesn't turn out far too eye-catching that way (not like the status-complete etc meta tags for example that are meant to stand out). (more) |
— | 9 months ago |
| Comment | Post #289392 |
@#53890 The code review category at software development isn't very active though, compared to the main Q&A, so I don't think it serves an advertising purpose. I think the main reason for adding several categories is if the posting policies are very different for certain types of questions. For examp... (more) |
— | 9 months ago |
| Comment | Post #289280 |
@#52991 Yeah it does also make sense to have the tags for very fundamental physics questions. "What is voltage?" or whatever (which may be more suitable for https://physics.codidact.com/ anyway). I think the key here is not to remove the tags, but to have active tag moderation and replace tags with s... (more) |
— | 9 months ago |
| Comment | Post #289074 |
This makes me recall the time when the biggest Swedish newspaper "DN" reported that Ericsson telecom had production problems due to lack of silicone. Some swede had translated the English term _silicon_ into the Swedish word _silikon_, meaning silicone. Naturally Ericsson were lacking silicon, not si... (more) |
— | 9 months ago |
| Comment | Post #289054 |
A submarine ought to be a pretty perfect RF environment with no unknowns. These controllers likely transmit on the 2.4GHz band and you'll know about every other such device present (if any). You are pretty much sitting inside a Faraday cage. Wired communication can actually be more noisy, because gro... (more) |
— | 10 months ago |
| Comment | Post #288550 |
@#36396 I can't really answer the question as whole and I haven't used most of these standards either, so I have no idea if it is correct enough to be answer. (more) |
— | 11 months ago |
| Comment | Post #288550 |
IEC 60364-5-52:2009 looks like it might be relevant for the actual calculation, though I haven't used it myself (doesn't seem harmonized under EU LVD Directive either). Regarding insulation there are plenty of application-specific standards, most notably the UN "ADR" directive regarding Carriage of D... (more) |
— | 11 months ago |
| Comment | Post #288404 |
I'd add a decoupling cap to the +12V line in addition to the TVS. The TVS will take the blow in case of spikes and the cap will ensure that the voltage stays otherwise stable. Something along the lines of 100nF X7R 50V will probably work ok. (more) |
— | 11 months ago |
| Comment | Post #288163 |
@#60399 The reason why one should avoid high ohm pull resistors is because RF energy from external spurious emissions (radiated or conducted) will be present and with 5V/1Mohm you only need >5uA to pull the line in the opposite direction. There's a big design difference between low power consumer app... (more) |
— | 11 months ago |
| Comment | Post #288163 |
Oh and 600W peak pulse is too weak TVS for automotive, you need 1500W. I don't remember which exact standard that requires this, but I do remember failing EMC testing once for this very reason. (more) |
— | 11 months ago |
| Comment | Post #288163 |
@#60399 So why did you ground pin 12, isn't that one to be used (ie tied to pin 8/input)? Do you intend to use this as a "watchdog" or as some "555 timer" or something else? (more) |
— | 11 months ago |
| Comment | Post #288163 |
@#60399 I mean the supply voltages. Placing TVS only makes sense on inputs/outputs, not in the middle of the circuit - everything after the voltage regular is to be regarded as relatively clean. You absolutely do need to have decoupling caps there however, 100nF close to the supply pin of the IC. Als... (more) |
— | 11 months ago |
| Comment | Post #288163 |
@#60399 Well that's a weird schematic. Why do you have zener diodes where one would expect to see capacitors? Are you running this from some raw battery voltage or something? Also if you have a pull-down on the P MOSFET, it will conduct as default, is this intentional? What are the voltages? (more) |
— | 11 months ago |
| Comment | Post #288163 |
You should be getting 0V, please post your schematic. Also don't use some horrible scanned datasheet, I found better ones here: https://www.datasheetcatalog.com/datasheets_pdf/C/D/4/0/CD4047.shtml. The Fairchild one shows how the trigger, clock and outputs act digitally (p7). (more) |
— | 11 months ago |
| Comment | Post #288118 |
@#60091 No, drain should be to the left, that's the whole trick and what the whole design is based on. It is purposely mounted backwards. The body diode should be included in the symbol to make it even clearer though. (more) |
— | 12 months ago |
| Comment | Post #288118 |
@#60091 It's more like: you get ESD protection for free. As for protecting the MOSFET I'm no expert but I believe the gate-source voltage is what might damage it and if so the TVS after the MOSFET does that. Of course it helps if the MOSFET is also rugged. I've used a similar polarity protection circ... (more) |
— | 12 months ago |
| Comment | Post #288118 |
@#60311 A regular zener is too slow to handle transients and ESD. The zener only protects against overvoltages. (more) |
— | 12 months ago |
| Comment | Post #288107 |
In that case you really need to specify what the voltage source is and why it would be vulnerable to such. (more) |
— | 12 months ago |
| Comment | Post #288107 |
The circuit is so artificial and abstract there's no telling what a cap would be good for. Mostly caps directly on the supply are there to act as "bulk caps", stabilizing the voltage coming from the supply. (more) |
— | 12 months ago |
| Comment | Post #288011 |
It might be common that students have to solder the boards themselves. And they (unfortunately) don't teach soldering in EE classes. Through-hole is the only sensible choice if you have zero experience with soldering. Apart from that, I agree that SMD layouts and 4 layer boards is the way to go for l... (more) |
— | about 1 year ago |
| Comment | Post #288010 |
@#54288 It's standard practice to always put a 100nF cap close to the supply pin on every IC on the board (unless the IC datasheet comes with specific recommendations). Particularly so on 2 layer boards since you'll have much worse EMC characteristics without a ground plane. (more) |
— | about 1 year ago |