Learning electronics: Release the Magic Blue Smoke

The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Learning electronics: Release the Magic Blue Smoke

Hexyflexy: Sep 2, 2011; asymptotically approaching one

silence_kit posted:

What you are saying might be true for 99% of circuits, but there are circuits for certain applications where it is important to actually co-simulate the components with the circuit board wiring during the design process. These applications tend to be concerned with figures of merit like phase balance, insertion loss, & reflection, which were mentioned.

There are also certain kinds of circuits, admittedly they are not very common, where basic circuit functions are are synthesized from the circuit board traces themselves. To not co-design the wiring with the components here would obviously be a a big mistake and would be designing in the dark.

I've been building something like a TMS device over the last few months when I've had time (I was bored), and it's been instructive how much attention I need to pay attention to the wiring and physical layout of the board. It needs to dump about a joule through a really precisely built inductor - which has been a pain. Those tiny little 6 pin boost converter chips are magic, can happily take 5v and put out 50v at a few hundred milliamps which'll happily drive a capacitor bank.

I wanted to simulate the thing in SPICE but I don't think it's going to be worth building a model over just scoping the thing and checking against calculations, every single trace or parasitic inductor is as important as the thing I'm actually trying to power up.

# ¿ Sep 19, 2019 19:21

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# ¿ May 9, 2024 01:32

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Zero VGS posted:

Oh yeah, they have what I need but I'm $11 short of $50. What else is good to buy there? Is there such thing as like an in-line DC circuit breaker or resettable fuse for around 50v/50a?

I have a lifetime of eutectic solder so not sure what other consumables I can think of.

Nice buttons or rotary encoders, I always get like 2 or 3 whenever I do an order because you never, ever have enough of them when you want one all of a sudden.

# ¿ Oct 7, 2019 20:08

Hexyflexy: Sep 2, 2011; asymptotically approaching one

I don't know anything about tank stuff, but I had a teacher in college that was a chemical sensor engineer before he left to teach and I remember him saying that ultrasonics were the standard fluid level sensor they used pretty much everywhere, especially if it was for something remotely hazodous. That was about 20 years ago though.

# ¿ Oct 14, 2019 18:46

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Ambrose Burnside posted:

I got myself one of those chinese 1000W zvs induction heaters with the water-cooled coil just to gently caress around with; I do a lot of delicate forging of v small titanium rod (1/4" dia and under) and i'd love love love to replace compressed gas + torches w something flameless and electric, and the stock i work has so little mass that 1000 watts should actually be more than enough for anything I could want to work on, assuming titanium heats up even a quarter as fast as a ferrous metal will.
anyways:
What are my power supply options if I'd like to avoid the expense of a UL-approved 24-48V 1500W+ switching supply without also burning my house down in the bargain? The youtube experimenter set seems to often use multiple 12V tractor/marine lead-acid batteries, but I'd have to buy those and the charger brand-new so I wouldn't save much. Maybe I can steal the transformer out of a microwave or sth like that

TiG welder unit?

# ¿ Oct 19, 2019 06:27

Hexyflexy: Sep 2, 2011; asymptotically approaching one

The A250 costs about $400, I'm trying to think of a really creative way to ask my employer for one. Like, it'd be really useful if the FPGA I'm programming got taken out of standby by a gamma ray burst in the next galaxy. I really want an electron detector, for no particular reason

# ¿ Nov 4, 2019 01:14

Hexyflexy: Sep 2, 2011; asymptotically approaching one

TotalLossBrain posted:

This requires a double integration on three axes and the propagated errors will likely be very bad with consumer-level parts.

You can only measure the gravity vector in the static state with accelerometers, which isn't useful for determining pose, but in any dynamic state it's that and worse (with no ground truth). I did some work ages ago on statistically determining pose on your hands with a few mems accelerometers/gyros strapped to end of finger/middle of finger/palm at some reasonable accuracy, and the like 10 different ways mems sensors can drift (up to like 30cm a minute linearly when integrated) are stupid.

I did a bunch of work after that on visual pattern recognition and pose estimation, and if that's acceptable for your use case, it works so much better and more simply it isn't worth trying approach one. You can probably download a code library off google that'll do it all for you at this point.

# ¿ Jan 13, 2020 23:50

Hexyflexy: Sep 2, 2011; asymptotically approaching one

peepsalot posted:

Already covered by KnifeWrench mostly, but I had a couple other points/clarifications to make.

No integration needed. For a pose-able mannequin, I'm assuming it would be mostly still, at least when "taking a sample", not flying around the room. In that case the accelerometer tells you pretty reliably which direction is "down", because it can sense the earth's gravity as long as its not in free-fall.

They only thing it doesn't tell you is the rotation about that vertical axis, in which case a magnetometer(+accelerometer combo) can be used as KnifeWrench mentioned.

So once you have two parts with a joint in-between (say a torso and upper arm), and each one knows which direction is down and which direction is north relative to itself, then you could use that to calculate the angles between the two.

But yeah I was kinda half-joking because that would be a ton of sensor modules to hook up (for ex on humanoid figure), and a bunch more trig to calculate the angles of the joints. But in theory I believe such a setup could function reasonably well.

Only thing I can add to this is that when I was doing the hand sensor project I specced 7-1-4C wire for connecting all the little sensor boards together, it's 4 core, 3.2mm external and can be flexed for a stupid number of cycles without breaking. Bit pricy though.

Also, just realised this second I've just done an hour long video conference wearing my IBM mainframe T-shirt that says "What weighs 2 tonnes and runs extremely quickly?" and nobody said anything. It's me, I weigh 2 tonnes and run very slowly.

# ¿ Jan 17, 2020 17:26

Hexyflexy: Sep 2, 2011; asymptotically approaching one

FISHMANPET posted:

No no this is good. The code to control the LED rings includes brightness , I'll have to dig closely into the code to figure out exactly how bright it makes them and also how bright they'll be by default. I think maybe I won't worry too much about the battery stuff for now. Also one of the original requirements was a power supply that would work internationally (he lives/works in Ireland but travels the world working for Microsoft), which is not a requirement of mine so a simpler power adapter like you linked would make me a lot more comfortable so I"ll look into that.

Those things are really forgiving, I know because while I've not wired them up and programmed them, my boyfriend has and there a thing with LED ring eyes sat on my kitchen shelf. You can drive them to *REALLY* bright, as in light up my kitchen bright.

# ¿ Jan 19, 2020 03:44

Hexyflexy: Sep 2, 2011; asymptotically approaching one

johnnyonetime posted:

Thanks for the tips. I was able to open up PuTTY and type characters into the terminal but still no luck downloading from the radio via CHIRP. I did swap to using the ring instead of the tip on the 3.5mm jack. I messed with it for an hour or so with no luck so I just ordered a usb version of the cable off eBay. I like the building aspect of amateur radio but at this point I'd rather use the radio than mess with building a cable any longer. Thanks!

I've found it really easy when building even slow interface stuff on breadboards or vero boards to accidentally end up with a lot of inductance on the lines. That's fine with some good gear on both ends, but problematic if it isn't. I bought a cable to use CHIRP on my cheapy CB radio, works a treat.

# ¿ Apr 1, 2020 20:25

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Ambrose Burnside posted:

I've seen a million 1N4004s and their ilk, for example, on circuit schematics so I know the role they play, as well as the general purpose of zener/schottky diodes and the like, but JEDEC codes seem incredibly opaque and useless ("1 means diode, N means N, everything else means [consult ten million datasheets]") alongside, idk, EECA schemes, where you can actually determine most of the critical parameters just based on the code, similar to what you'd expect from resistors. or is there a reliable rule for knowing the practical difference between a 1N4001/4007, say, or other comparable components where the package is identical?

Try figuring out why various MOSFET's are coded the way they are. I mean, BC548, that's a good name for a transistor, I can remember that, FQP30N06L (neato ones), what even the gently caress is that.

# ¿ Apr 3, 2020 14:58

Hexyflexy: Sep 2, 2011; asymptotically approaching one

cakesmith handyman posted:

I found the other plugs called 2.8mm 2 pin so those are sorted, but the battery and motor connectors are eluding me.

Something like this?

https://www.ebay.com/itm/T-Type-2-Pin-DC-Power-Connector-Plug-For-VHF-UHF-Kenwood-Yaesu-Icom-Radio-Cable-/162826459803

# ¿ Oct 18, 2020 16:15

Hexyflexy: Sep 2, 2011; asymptotically approaching one

I immediately bought both his books, thanks!

# ¿ Apr 24, 2021 19:34

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Forseti posted:

that really is a fantastic animation

I'm posting these to my friends at the moment, they're brilliant

# ¿ Sep 14, 2021 17:27

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Leandros posted:

Are (lithium) battery-powered devices designed with the capabilities of the sourced batteries in mind? By which I mean, I know that there's a fair bit of variation in e.g. 18650 chemistry/quality/capacity/current capabilities, and I would like to replace a set of them in my vacuum with new ones.
Ideally I want to go for the highest capacity/current combination, but I was wondering if that might blow up my batteries because their internal resistance is lower than expected by the design, or something like that.

Not my field but my bf builds electronic gadgets, art things, and he's spent a stupid amount of time the last couple of years working out how different types of battery chemistry and manufacturer deal with low power draw conditions, because it makes a huge amount of difference to how a thing can sit at idle on a shelf before you turn it on ocasionally.

I've refurbished a few bits of equipment e.g. 1980s fluke multimeters and I've been careful to get something as similar as possible to the original batteries, because I'm wary the engineer who designed the battery maintainance circuit was expecting a specific internal resistance or something.

# ¿ Sep 14, 2021 17:49

Hexyflexy: Sep 2, 2011; asymptotically approaching one

silence_kit posted:

In microwave class, one of the results of network theory which is usually presented is that it is impossible for a three port network to be simultaneously lossless, reciprocal, and matched.

I seriously appreciate these slides

# ¿ Dec 4, 2021 22:44

Hexyflexy: Sep 2, 2011; asymptotically approaching one

petit choux posted:

Wow, thanks for the great answer. I'd still love to hear anybody else weigh in on this. Here is a link to the ones I just got:

https://www.digikey.com/en/products...xrx50VurfaC2wO7

ED: Oh, and I'll need to sever the old one before trying the new one, right?

I can recommend those encoders made by Bourns Inc, my partner uses them in stuff he builds and we've never had a problem with them, unlike cheapo ones.

# ¿ Jan 11, 2022 18:08

Hexyflexy: Sep 2, 2011; asymptotically approaching one

PRADA SLUT posted:

What's the best resource for in-depth DCDC switcher design? I'm not talking like the hobbyist youtuber, "if the switching frequency is faster, you use smaller inductors", I'm looking for an engineering analysis of switcher topology, component sizing calculations, output filter types, considerations for loads, etc.

There are a couple things that I've just been following the data sheets on, and I'm starting to need to really understand why the data sheets suggests these auxiliary components, because the operating environment of a project I'm working on is less friendly to hardware.

e.g.,
For cap sizing, am I just looking at the RC time constant and assuming I'm maintaining the entirety of the off cycle? Or just enough to address the dI/dt from the inductor side?
For inductor sizing, do I assume energy storage of 1/2LI^2 maintaining the entirety of the off cycle?
What the relationship between these elements, aside from ripple? Like if I do a fat oversizing of the both components, what's the downside (besides physical size)?
Does this change with an inductive load, or am I just using a standard P-FET with a flyback on the output?
What's the EMI advantage/disadvantage of PWM vs controlling an enable on a duty-cycle-locked oscillator? How would I calculate the assumed EMI level from these modes? Is this a calculation just from the assumed PWM duty cycle and then the output stability of the system? (while I could do an SI/EMI simulation, I would like to know how I would "ballpark" the value ahead of time).

Anyway, not looking for specific answers, but more for resources that address switching design with a level of detail similar to the above. I've already read the entry in AoE and a few assorted textbooks, if relevant.

Not sure if this is the kind of thing you're looking for, but if you want some uni level lectures on various power electronics topics, I went through a fair few of https://www.youtube.com/@katkimshow/videos her lectures a few years ago when I was looking and they were very helpful.

Beyond that I'd suggest searching for "Texas Instruments ... buck converter" etc on youtube, they do a whole load of lectures on most of the chips they make and design issues around using them.

# ¿ Jun 7, 2023 21:28

Hexyflexy: Sep 2, 2011; asymptotically approaching one

PRADA SLUT posted:

Yeah, I understand the operation of DCDC switchers, but I need to do a fairly complex bring-up on an FPGA for RF with like 8 different voltage levels, switchers, and power sequencing, in an environment where I expect various elements to fail. So, I'm trying to address every possible source of FMEA or EMI/EMC.

Like one thing I can't figure out for the life of me is how to figure out the assumed EMI comparing PWM vs a constant oscillator (controlled simply as an on/off) control on the feedback loop. Normally I could assume taking octaves of the switching frequency along with a current sampling and that's my noise profile, but if I'm working with an EMI-sensitive device, I need to know more specifically how I could assume the variability in switching frequency to design a filter around it. And on a constant oscillator, I'm going to "drop out" on occasion and the frequency per unit time will change slightly.

That's when you phone up your application engineer contact at whoever makes that FPGA!

# ¿ Jun 8, 2023 22:35

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Harvey Baldman posted:

I have a remote control for my projector that broke. I could hear some stuff rattling around inside so I cracked it open and discovered a bunch of components had basically come loose from the PCB somehow.

The resistor I'm sure I can solder back on, but there's a little thing next to it - that black piece with an "N" stamped on top - that I don't recognize or have an easy way of identifying.

Is there any way to figure out what needs to be soldered back into that spot? The piece with the N on it is clearly busted, there are no contacts on it anymore.

Just wondering if I can figure out how to fix this without spending a ton on a whole new remote.

The L1( N )'s an inductor and the C3 is a capacitor. I'm guessing they're part of some kind of boost converter so you'd need to know the original value of it to make it work correctly.

Can you get a side lit shot of that big IC on the board? Might be able to look up its datasheet if we can see its id code.

Are there any components on the other side of the board?

# ¿ Nov 1, 2023 00:18

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Splode posted:

I think the switchmode power supply is the chip U2 with marking AX21. I'm not finding much online though.

Annoying thing is I swear I've seen one of those mentioned on eevblog.

E: Oh neat, I couldn't figure out which one of those alternate part names was the thing.

# ¿ Nov 1, 2023 04:30

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# ¿ May 9, 2024 01:32

Hexyflexy: Sep 2, 2011; asymptotically approaching one

Bosch got you covered with a sniffer chip

https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bme688-ds000.pdf

# ¿ Mar 22, 2024 23:26

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