Activity for Lundin
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Comment | Post #281064 |
@mrwavelets So the MOSFET is not there to give a higher voltage needed for the amplitude? In that case it isn't necessary, since your particular part can drive a relatively high current directly. (more) |
— | about 3 years ago |
| Comment | Post #281064 |
How do you intend to connect it to the MOSFET? If you mean to have the 555 timer on the gate, then you'll have to be very careful with which part to pick, since most MOSFET aren't fast enough to live up to your realtime spec. What 555 timer are you using? In case it's a single chip IC, there should b... (more) |
— | about 3 years ago |
| Comment | Post #281059 |
This is far from my area of expertise, but have you checked Analog Devices? They have tonnes of more or less exotic amplifiers. https://www.analog.com/en/products/rf-microwave/rf-amplifiers.html. If you for example check their "Wideband Distributed Amplifiers" they have lots of parts explicitly desig... (more) |
— | about 3 years ago |
| Comment | Post #281061 |
Anyway, I would strongly suspect that the root of your problem is the solder station itself. What brand and what temperature are you using, assuming it is temperature controlled in the first place? Coating the tips when not using them is a good idea btw, so keep doing that. (more) |
— | about 3 years ago |
| Comment | Post #281061 |
The flux core in RoHS solder is very unhealthy too. So in case you worry about your kid putting it in their mouth, it's not a better alternative than leaded. (more) |
— | about 3 years ago |
| Comment | Post #281021 |
And then finally a question along the lines of "what would happen if all digital currency gets destroyed" might also be suitable for Scientific Speculation. Now, if you are looking for a _debate_ about why digital currency is bad, then none of these sites are suitable, since this is a Q&A platform. (more) |
— | about 3 years ago |
| Comment | Post #281021 |
@JohnDoea There's several separate questions here: is it electrically possible to have some manner of global EMP event - that question could be asked either here or on the Physics site. If it's related to power grids etc, then here. If it's related to astronomy or nature forces, then the physics site... (more) |
— | about 3 years ago |
| Comment | Post #281021 |
I think this is more related to astronomy than EE. Although somewhat on-topic here, the question would probably have been more at home at https://physics.codidact.com/. Like for example, is it feasible that some really big comet passing close to earth has a wildly different potential and then cause s... (more) |
— | about 3 years ago |
| Comment | Post #280675 |
@Chupacabras Aim for one with 20mA, that's more industry standard. Also for 1st source I'd probably pick a silicon vendor with more self-respect than someone who calls themselves "MaxLinear" - there's nothing wrong with their parts, it's Sipex/Exar/whatever, they change name every year. But I laugh w... (more) |
— | about 3 years ago |
| Comment | Post #280894 |
@2kind So toss in a NPN and a pull resistor to the right side. Signal polarity should be trivial to fix. Also, if you don't need the voltage divider R2 you could simply use an internal MCU pull resistor. (more) |
— | about 3 years ago |
| Comment | Post #280675 |
@Chupacabras Did you try the above mentioned XR46010ISBTR? Looks fairly compatible, though I'd double check the pinout because SOT-23 pin numbers aren't that well standardized. (more) |
— | about 3 years ago |
| Comment | Post #280672 |
@Chupacabras The 90mA current is an odd case, most LEDs are rated at 20mA. Also, you can get extreme super bright LEDs that shine like the sun with several candela at 20mA, why focusing on the LED is easier. (more) |
— | about 3 years ago |
| Comment | Post #280672 |
It looks like a board where anything can fail at any moment though... Anyway, why not just pick a brighter LED? So much easier. (more) |
— | about 3 years ago |
| Comment | Post #280672 |
Hmm, I don't think failing parts is necessarily the problem given the pics. The solder job is truly awful and besides you got corrosion of some kind all over, to the point where I would suspect that the board is water damaged. (more) |
— | over 3 years ago |
| Comment | Post #280713 |
You can easily answer this by not connecting the probe ground to the DUT and measure something, then connect the ground and measure again. The signal that looks like crap is the one that you don't want. (more) |
— | over 3 years ago |
| Comment | Post #280675 |
@Chupacabras As noted, this was a PNP part but you need N-channel. Just search for SOT23 LED Driver and you get plenty of results. If you wish the exact part, then you have to put more effort into the question, adding the print on the IC and preferably also a photo. (more) |
— | over 3 years ago |
| Comment | Post #280675 |
Closest match on Mouser appears to be XR46010ISBTR with NPN. SOT-23 pinout standardization leaves a lot to be desired though, so I'd be very careful double-checking the pins of your layout symbol vs datasheet. Don't trust the schematic pin numbers. (more) |
— | over 3 years ago |
| Comment | Post #280672 |
Is R1 really 1 ohm? Then what purpose does it fill? (more) |
— | over 3 years ago |
| Comment | Post #280595 |
Semiconductor companies in general and NXP in particular let their "FAE" play around with evaluation boards and write app notes on their spare time. That is, engineers with incredibly broad but rather shallow knowledge. Mostly these should be regarded as some hints to get people started (with the com... (more) |
— | over 3 years ago |
| Comment | Post #280586 |
As for the question "what is AC frequency", that's a valid question. Alternating currents means you have several phases (simply put: several signals/wires) between which the current alternates. The current in each phase comes as a sine wave and the "AC frequency" is simply the (2*PI) period of the si... (more) |
— | over 3 years ago |
| Comment | Post #280586 |
This entirely depends on what motor that sits inside the oven and how it was designed. I wouldn't assume that every microwave that has ever been made is using the same kind of motor. You'll have to come up with some manner of partnumber or preferably a datasheet of the motor, or I don't think this qu... (more) |
— | over 3 years ago |
| Comment | Post #280582 |
@Olin Lathrop I don't think there's any relation between the number of categories and the site activity. That site like several others struggles because it had too few veteran/enthusiast users from the start. That being said, we aren't exactly drowning in new posts either, so yeah maybe we should wa... (more) |
— | over 3 years ago |
| Comment | Post #280582 |
@Olin Lathrop The benefit of a different category is that we can apply different posting rules there. For example if someone wants help to trouble-shoot their program, we'll want a minimum code example and/or the relevant schematic page only. However, if they are looking for a design review we might ... (more) |
— | over 3 years ago |
| Comment | Post #280564 |
@ Monica Cellio Embedded systems programming is currently off-topic at Software Development but on-topic here. (more) |
— | over 3 years ago |
| Comment | Post #280479 |
The 6A current limit sounds like hogwash. The human body has too high resistance to ever get close to currents like that. And the currents are what matter here, not the voltages. (more) |
— | over 3 years ago |
| Comment | Post #280479 |
(Disclaimer: I don't know much about medicine save for a CPR class.) To stop the heart you just need to make the (I think they are called) beta receptors freak out, which only takes a relatively small current. These control the heart rhythm and if they stop acting reliable you get a heart failure. Th... (more) |
— | over 3 years ago |
| Comment | Post #280454 |
The way I usually do this is to buy pre-programmed MCUs for high volume products ~1000pcs/year, keep the SWD connector footprint on the board but don't mount it. For products of lower volumes or products where you expect a lot of software releases, keep the connector and use an in-circuit programmer.... (more) |
— | over 3 years ago |
| Comment | Post #280450 |
@Olin Lathrop Maybe he was rather holding on to a metal truck chassis shorted to 700kV while touching the ground with another body part. Though I suppose you need quite a big clearance distance for 700kV, several meters perhaps. (more) |
— | over 3 years ago |
| Comment | Post #280454 |
Also, justifying development costs of pogo pins, bootloaders etc means that you must have large volumes. Engineers cost money. How many 2x5 1.27mm SWD connectors can you buy for the engineer salary required to develop this? Almost certainly far more than a product life time of such connectors. (more) |
— | over 3 years ago |
| Comment | Post #280454 |
"I don't feel ready to commit to having the chips pre-programmed" Why not? This is no effort at all, you just contact a company dealing with such parts, give the binary to them (NDA if necessary) and buy the pre-programmed MCUs from them instead of the silicon vendor. There's usually no big MOQ. (more) |
— | over 3 years ago |
| Comment | Post #280450 |
As for your grandfather's story, it sounds like hogwash. For something to actually catch fire, you would need several Ampere running through it. The resistance of the human body + clothes, shoes (likely rubber) etc + the ground itself, is many Megaohms. So even if someone manages to charge their body... (more) |
— | over 3 years ago |
| Comment | Post #280450 |
As for why a certain voltage is used... the aim of an electric chair isn't to burn someone to crisp by making their whole body a conductor for high current, that would be extremely unethical and similar to burning someone alive. (more) |
— | over 3 years ago |
| Comment | Post #280450 |
@Olin Lathrop Well... nobody _has_ to design them. Engineers with some sort of moral code might refuse to do so. But I agree that questions regarding why a certain voltage is used by certain electrical equipment are on-topic here. (more) |
— | over 3 years ago |
| Comment | Post #280394 |
Yeah the TVS part should perhaps have been posted as a separate question. (more) |
— | over 3 years ago |
| Comment | Post #280393 |
@Pete W Yeah indeed, I'll already have some 33V TVS elsewhere in the BOM. As for replacing the relay, indeed some manner of SSR-like solution is preferable (faster, cheaper, more reliable). There's various "smart high side drivers" that are very good for this and they can also drive analog signals. ... (more) |
— | over 3 years ago |
| Comment | Post #280394 |
Thanks for your reply. Regarding the TVS it would be 30V-something zener breakdown voltage, mounted with the anode towards ground. The use-case I had in mind is something like an industrial/automotive application with a fairly long cable (3-5m) between the driver circuit on the PCB and the actual coi... (more) |
— | over 3 years ago |
| Comment | Post #280392 |
That _is_ strange. I'm guessing they got the scale of y axis of the graph wrong. Because if the sensor was truly as good as that graph showed, you can be sure they would have advertised it. (more) |
— | over 3 years ago |
| Comment | Post #279987 |
After 5 consecutive then there must be a stuff bit. (more) |
— | over 3 years ago |
| Comment | Post #279987 |
CAN (and UART) utilizes bit stuffing, so you won't get 9 adjacent zeroes or there will be a stuff error. (more) |
— | over 3 years ago |
| Comment | Post #279886 |
@Michaël Bensimhoun I don't know, hence the question. I was thinking of aluminium electrolytes but I guess the cap chemistry matters a lot? (more) |
— | over 3 years ago |
| Comment | Post #279886 |
Curious that you mention bypass caps in the context of ESD, since a discharge is a extreme spike event, unlike the average EMI. To what extent do they help against ESD, aren't they generally far too slow, compared to TVS diodes etc? (more) |
— | over 3 years ago |
| Comment | Post #279876 |
It sounds like a layout problem, though it is of course impossible to say without seeing the PCB layout. Otherwise, the most common reason for failing ESD tests is that something isn't grounded that should be grounded. Also, how is the shield connected? Did you ground it at one side of the cable or b... (more) |
— | over 3 years ago |
| Comment | Post #279804 |
My point here is that we discuss things as a community and come up with a consensus about what to do with these kind of questions _before_ we run off to moderate posts. The current [on-topic/off-topic](https://electrical.codidact.com/help/topics) list doesn't even address repair questions. (more) |
— | over 3 years ago |
| Comment | Post #279796 |
The fuse F1 on the top side lower right corner looks like it's been through a lot of heat, and the solder joints look a bit fishy too. These are supposed to be recoverable fuses, but I'd definitely replace that one still, though I can't tell what exact part it is. Though of course, if it is blown, th... (more) |
— | over 3 years ago |
| Comment | Post #279796 |
PCB side 2 shows a lot of signs of a poor solder job. Check the top right corner of the last pic for example (looks like 0402). Probably they configured the placement machine poorly - there's too much solder everywhere and the potential for shorts looks extensive. Get some dirt on the board and anyth... (more) |
— | over 3 years ago |
| Comment | Post #279796 |
This post is discussed on meta [here](https://electrical.codidact.com/questions/279784). (more) |
— | over 3 years ago |
| Comment | Post #279804 |
There is not yet any consensus about what to do with repair questions and to what extent they are allowed. It is not yet addressed by the site policies as they stand. This meta post is a good place to discuss this and perhaps come up with specific rules. But until there is community consensus, please... (more) |
— | over 3 years ago |
| Comment | Post #279739 |
Simply mask them before soldering? That is, put a piece of tape across the opening. Still, I don't quite understand how you can manage to get flux inside the connector. Use a flux pen or such, don't bathe the whole board in it straight from a bottle or something. (more) |
— | over 3 years ago |
| Comment | Post #279494 |
Basically, every EE needs to be _aware_ of the bullet points in my answer, even if they don't know how to perform them (prettily) in person. For example, one cannot do a decent PCB layout if one isn't aware of how heat from the soldering process spreads through the ground plane(s) and therefore route... (more) |
— | over 3 years ago |
| Comment | Post #279492 |
@manassehkatz As I said, it's another story :) Meaning it's a hot potato that will get debated whether or not it is on topic... elsewhere. (more) |
— | over 3 years ago |