Activity for Lundin
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Edit | Post #281971 |
Post edited: |
— | over 3 years ago |
| Comment | Post #281974 |
Yeah maybe nearby walls could be an issue. When I did this I had the antenna mounted vertically against a metal plate surface approx 300x300mm but the fixture was placed around 1-2 meters from a wall. Consisting of plaster, not reinforced concrete, but still. Maybe if I use one that's 1x1m and keep i... (more) |
— | over 3 years ago |
| Comment | Post #281971 |
@Andy aka The purpose here is to measure pre-made antennas from various manufacturers to see if they can be used for the specific frequency. Still, if EMI is the cause, then moving the fundamental to some quiet band won't be reliable either, because I'd still get harmonics from TV/radio broadcasts e... (more) |
— | over 3 years ago |
| Edit | Post #281971 | Initial revision | — | over 3 years ago |
| Question | — |
Is there a way to reliably measure antenna return loss outside a lab? Assume I'm a complete beginner at RF. Is there a way to measure return loss of an antenna, in such a manner that I can reliably reproduce the measurement later on? What I'm talking about is producing the antenna characteristic graph to show what frequency it was adapted to and how wide it is. ... (more) |
— | over 3 years ago |
| Comment | Post #281247 |
The aim of this site is surely to be newbie-friendly to _electrical engineering newbies_ not to _general electronics newbies_. That means we should welcome engineering students or fresh out of school EE to ask questions here. If such users feel unwelcome, we are doing it wrong. If some John Doe who i... (more) |
— | over 3 years ago |
| Comment | Post #281540 |
@coquelicot It means buying from component traders instead of the usual well-known vendors. There is a huge market of people buying and selling electronic components similar to stock trading. It's the last resort where you go when you can't buy obsolete parts from a trusted source. And it is filled ... (more) |
— | over 3 years ago |
| Comment | Post #281540 |
What makes you think it is fake in the first place? Did you buy it from the spot market? (more) |
— | over 3 years ago |
| Comment | Post #281444 |
Except it's not wands they are waving, it is 1/2 wave antennas! (more) |
— | over 3 years ago |
| Edit | Post #281437 |
Post edited: |
— | over 3 years ago |
| Suggested Edit | Post #281437 |
Suggested edit: (more) |
helpful | over 3 years ago |
| Comment | Post #281437 |
I'm hardly an expert on antennas, just wondering how these hobbyist modules went from hobbyist status to reference design status... Here's an interesting article on the topic though: https://www.hindawi.com/journals/ijap/2018/5172960/ (more) |
— | over 3 years ago |
| Comment | Post #281437 |
What makes you think that antenna _is_ properly designed though? I hear nothing but bad things about these ESP32 modules. Anyway, you want an antenna to radiate, but your don't want regular traces to radiate. (more) |
— | over 3 years ago |
| Edit | Post #281361 |
Post edited: Added some suitable tags |
— | over 3 years ago |
| Suggested Edit | Post #281361 |
Suggested edit: Added some suitable tags (more) |
helpful | over 3 years ago |
| Comment | Post #281246 |
Nobody dismissed anyone...? The question sits at 5 up-votes, 0 down-votes. I'd be curious to learn the reason too but nobody seems to know. (more) |
— | over 3 years ago |
| Edit | Post #281289 |
Post edited: Removed some irrelevant tags. Added "reverse engineering". |
— | over 3 years ago |
| Suggested Edit | Post #281289 |
Suggested edit: Removed some irrelevant tags. Added "reverse engineering". (more) |
helpful | over 3 years ago |
| Comment | Post #281289 |
It's common that automotive MCUs come with custom markings. So that might not be a part number at all, only some program version. Any semiconductor company logo on them? Could also be a custom SoC or FPGA. (more) |
— | over 3 years ago |
| Edit | Post #281249 |
Post edited: |
— | over 3 years ago |
| Comment | Post #281246 |
Li/Ion and LiPo are generally around 3.8 - 4V somewhere though, at least modern ones. And I think 3.3V goes back to the early 1990s somewhere, it probably pre-dates such batteries. So this doesn't explain where 3.3V comes from, specifically. I think this rather has to do with CPU core voltages and CP... (more) |
— | over 3 years ago |
| Suggested Edit | Post #281249 |
Suggested edit: (more) |
helpful | over 3 years ago |
| Edit | Post #281251 | Initial revision | — | over 3 years ago |
| Answer | — |
A: Is there a tool or trick for bending TO220 leads There's lots of specialized tools for various through-hole components overall, all of them generally called "lead benders". For TO-220 it appears that the term is lead bending/forming pliers. And there exist lots of different versions, depending on how you want the legs to go. This site (I'm not ... (more) |
— | over 3 years ago |
| Comment | Post #281249 |
Why would you bend them in the direction of that picture though? Are you using heatsink? (more) |
— | over 3 years ago |
| Comment | Post #281165 |
In this case it is LoRa, which is supposed to use spread spectrum to compensate for high output power, so I don't get why the harmonics are that prominent. It's max 14dBm carrier if I remember correctly. (more) |
— | over 3 years ago |
| Comment | Post #281165 |
Just curious since my experience (I'm definitely not a RF designer) is that PI filters are mostly used for general EMC, like when you need to block emissions over a very broad frequency range. But harmonics are specific and you know where they will be at, so why not just get rid of them. (more) |
— | over 3 years ago |
| Comment | Post #281165 |
What's the reason you'd pick a PI low pass over a Chebyshev one? I thought Chebyshev were ideal since they give a much steeper dip after carrier? (more) |
— | over 3 years ago |
| Comment | Post #281144 |
In my opinion you can't really solder 0603 or smaller with the standard tips, nor fine pitch QFP, QFN etc. I always use a small tip for most things SMD. (more) |
— | over 3 years ago |
| Comment | Post #281066 |
@coquelicot You need to go some 30-40 dgr C higher for RoHS solder. However, if you have the possibility to set the temperature manually, you put it much higher than the melting point anyway, which is the temperature that affects the tip life. Leaded melts around 180, RoHS around 220 and I put the i... (more) |
— | over 3 years ago |
| Comment | Post #281083 |
Your 6th harmonic are over the spurious emission limits on a LoRa? That sounds strange, did you deviate a lot from reference designs? How many dBm are the harmonics at and what's your carrier output power? (more) |
— | over 3 years ago |
| Comment | Post #281083 |
I guess question #1 here is: is this a simplex or duplex radio? Any antenna switches etc present? (more) |
— | over 3 years ago |
| Comment | Post #281070 |
@Mu3 I think the debacle ended when LT merged with AD. There's no such database of part markings AFAIK, though some manufacturers provide a cross ref service on their site. In practice this is about asking a veteran EE - "I need a buck/boost part, who should I check with?". Or you can ask this of an ... (more) |
— | almost 4 years ago |
| Edit | Post #281070 | Initial revision | — | almost 4 years ago |
| Answer | — |
A: Why do DC/DC switching controllers seem to favour the buck-boost topology over similar ones like Cuk, SEPIC and Zeta? I'm not sure there's a technical reason, except usually the offered parts are multi-topology and then they could be listed as buck-boost while they at the same time could as well be used as flyback, SEPIC etc. This seems to be the case for TI and Maxim, which at a glance seem to call everything "... (more) |
— | almost 4 years ago |
| 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) |
— | almost 4 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) |
— | almost 4 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) |
— | almost 4 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) |
— | almost 4 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) |
— | almost 4 years ago |
| Edit | Post #281021 |
Post edited: More relevant tags |
— | almost 4 years ago |
| Suggested Edit | Post #281021 |
Suggested edit: More relevant tags (more) |
helpful | almost 4 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) |
— | almost 4 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) |
— | almost 4 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) |
— | almost 4 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) |
— | almost 4 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) |
— | almost 4 years ago |
| Edit | Post #280894 |
Post edited: |
— | almost 4 years ago |
| Edit | Post #280894 | Initial revision | — | almost 4 years ago |
| Answer | — |
A: Isolated Digital Input - Overvoltage protection > Step 1: Since 3V3ISO would be LDO driven I would probably add a diode with the anode connected to the LDO output and a cathode connected with the LDO input to prevent the LDO to have output higher than the input. Based on my experience they tend not to love that. I haven't post that because I haven... (more) |
— | almost 4 years ago |