As Altima said, it’s a 22ohm SMD resistor. You’ll need to measure it to get the package size.
Unfortunately resistors don’t really just burn out. If the resistor did cause damage from overheating, it’s because something drew too much current. My guess is there’s a short somewhere else, but there’s almost certainly more damage than that resistor.
The fundamental concept at work in making an electromagnet is Lenz’s law. Here’s a Khan academy video on the topic. www.youtube.com/watch?v=xxZenoBs2Pg
You can determine the power of a magnet (very roughly) using the following equation:
B = μ₀ * n * I
Where:
B is the magnetic field strength in teslas (T) or gauss (G). μ₀ is the permeability of free space, approximately equal to 4π × 10^-7 T·m/A. n is the number of turns per unit length of the coil (turns per meter). I is the current flowing through the coil in amperes (A).
So the number of turns matters, and also the current matters.
But there’s a third thing, and I think that’s the problem you’re having: This piece of wire is conductive, and the nail is conductive, and there doesn’t seem to be any insulation on the wire. Because of that, the current flows through the wire on one side, into the nail and across it, then out the wire on the other side. The current needs to flow in loops without being able to take any other path, The coil of wire and the current flowing around in circles is what’s required.
What you want is a long piece of wire with insulation on it. Then you wrap it around the nail, and then apply a battery across the wire. A 1.5V battery probably won’t have much punch so you might not be able to get much of a magnet, but a 9V battery should do it quite well. What will happen is the current flowing through the wire will create a magnetic field, which will magnetize the nail, which will create a magnet you can use to pick up coins.
A lot of the time, people run demos using special wire for creating magnets that’s copper with a very thin clear insulating coating on it, so you might think you’re looking at someone just making a loop of regular wire, but the insulation is key to the whole thing working.
In my experience a large 1.5v D cell works best, as the limiting factor is generally current not coil resistance, unless you wind thousands of turns of fine wire.
It looks like 1GΩ (black-brown-white gold). But that doesn't sound likely unless you have a very high voltage bread maker.
If we treat the black band as discolored-brown, and read it the other way, we get (yellow - white - brown - brown) which is 490Ω and closer to your measured value. I wouldn't rule out (yellow - white red - brown) either at 4.9 kΩ, although that doesn't match closely to your measurement.
A good question is 'why did the resistor burn?'. If I didn't know why, then I would assume that replacing it will just result in it burning again, although maybe not immediately.
Well, arguably keeping the resistor the same value would result in a somewhat known state, and changing it would put it in an unknown state. The unknown state could be better or worse. I can't see enough to know what the circuit does to say.
What you could do instead, is set the resistor to the same value, but rated for higher thermal dissipation. Then measure how hot it gets to identify if the real problem is somewhere else. Another part might burn/explode instead though, so I'd consider carefully how to proceed, and probably wear goggles + have a fire extinguisher in the room.
My main concern is by 'fixing' it with a resistor with higher thermal dissipation, I've created a fire hazard because that dissipated heat now has to 'go somewhere', which may be the plastic case. A thermal camera is handy to see if some part of the board gets unacceptably hot during normal operation.
Thank you for the detailed insight! I miss some basics in electronics but am eager to learn how to test and fix circuits.
Years ago I tried to repair an old keyboard/synthesizer by cleaning it and replacing leaked/bloated capacitors. Unfortunately the onboard sound memory could not be loaded anymore or was wiped entirely as far as I understood. But due to lack of knowledge (me and community that time) it was too complex to got the keyboard up and running again. It’s sometimes sad to loose good hardware…
Back to the resistor/thread: I can’t imagine a resistor to be the source of the problem. Isn’t it more possible that a capacitor wears out or a transistor cooling fails?
However, if the circuit was in an abnormal state (e.g. the contact with the case), then a resistor could very well blow. It would not be surprising if it took some other components down with it, and that this damage is not obvious yet. “The transistor blows to protect the fuse” is a common fail-state, facetiously stated.
Another possibility is just… bad design. You could call me adequate at circuit design (I mostly design prototypes, not finished systems that have to last thousands of hours), but regularly see commercial products designed poorly with some stupid point of failure. For example, using a 1 watt resistor that is dissipating close to 1 watt, instead of designing a more efficient system that doesn’t require dissipating heat at all.
I spend a lot of time answering questions for people just getting started. Probably 75% of them boil down to a few things. Here is that list in case amusing / useful:
Relays are not a great solution in general, and there are many better alternatives (MOSFET, SSR, etc).
Output impedance matters: you can’t power a huge motor off a microcontroller pin.
Back-EMF from inductive loads can burn out your control system unless you add a protection diode.
Lead acid batteries aren’t a magic solution to power everything. Especially automotive ones. Understand and use lithium ion.
Connecting LEDs in parallel then adding a single resistor will lead to failure pretty quickly.
Generally, don’t pass significant power through a switch. Use the switch to control the state of a power MOSFET or similar.
Button debouncing.
Most of the rest is refusing to do other people’s homework, help people build weapons, or do unwise things with mains power / high voltage / centrifuges. Occasionally people ask me really interesting questions though, so I don’t mind that the interactions are a bit scripted the rest of the time! I’ve noticed on Lemmy I’ve gotten much more interesting questions so far!
The case is basically fully metal, just a bit of plastic inside for mounting the PCB to and a few other bits of plastic outside. Plus there is a temperature fuse in the case also.
From the resistor size (11.5 x 4.5mm) I think it would have been a 2W resistor when comparing to sizes on Digikey. I made a 500 Ohm 2W resistor from 8 1/4W 1K resistors then put a larger resistor in parallel to that to bring it down, measured it to 489 Ohms.
I’m going to run it a few times then open it up again to see if there is any new damage to the board before returning it.
Thanks! I’ll try replacing it with a 490 ohm resistor and see if it works again.
The element in the bread maker looks like it came loose a bit and made slight contact with the internal metal housing. I wonder if that caused the resistive element to sink more current than the PCB was designed for, burning out the resistor.
That sounds like a possible fail state. Also shitty design. It should use a resettable thermal fuse or something to detect faults without parts burning.
Ages ago (80’s I think) there was talk of making lead free solder the only type that was available to consumers, and my great uncle (a deal horder) went out and got 2 cases of radioshack 64/40 resin core. Pretty sure it’s the same stuff you can still buy today, but I’ve got another 4 spools in my kit (that are old enough to drink).
In my uncles defense sometimes his deal hording paid off. He once saved a family reunion when our venue fell through because he happened to have a dozen brand new hibachi grills in the apartment he rented just for his stuff. And he made a small fortune when he bought a bunch of freon before it went off the market.
It’s not that you can’t make a more efficient device without it. Hell, if you wanted to impress people, you can absolutely populate a board with IC’s and traces and build your own logic.
Orrrrr you could spend $45 to get a full GPIO header backed behind a vast online electronics community. Tbh pi’s, arduinos, and other ARM core hobby kits give you a root skillset to base any project on. Once you can get logic through your code, there’e no need to figure out wire logic if you can program based on I/O and software variables. But it -is- a different skillset that you’ll need to learn to use it efficiently.
No beeper in this photo. Could be a piezoelectric disk hidden some where they are small and thin. what’s on the other side of the PCB? Also look stuck to the plastic, piezos are often stuck to the casing to use it as a sounding board.
Edit: not sure what the yellow thing, cap maybe, can you get a better picture of the text on it ?
There’s actually a decent amount of research into exactly this sort of thing, called, appropriately, “energy harvesting”. Depending on the application, it can be fairly effective. I know that vibration energy harvesting has been successfully in machinery monitoring applications, for example. I haven’t looked much into stray EM harvesting, but I’m sure it is possible…most likely to supplement a primary energy source rather than as the main source itself. But, yeah, for sure it’s an interesting topic with a fairly good amount of study into it…I think the University of Michigan had a few good research programs related to harvesting for ultra low power applications. You night check out some of what they’ve done
i would follow the wires until you find either a black plastic cylinder around 5-10mm in diameter with a hole on top, or a brass-colored disc around an inch in diameter. that would most likely be a piezo speaker.
A lot of kettles use sound to indicate state. If you’re nervous you should alert your local authorities rather than wait. Better safe than sorry.
Edit: Sorry folks. I thought op meant beeper as in the radio device. It’s late where I am and I’m tired, hah. Was just trying to encourage a bit of safety.
No. SAS is a different protocol and requires a different host controller. SAS controllers can typically handle SATA drives, but not the other way around.
If this is for a server or desktop machine, you could install a PCIe SAS HBA.
KiCad. Stay away from closed-source tools. They’ll all try to press out the max amount of money sooner or later. Or get bought and discontinued for eliminating competition.
Im surprised they make fans this small but i think they are really weak. Im gonna order one of them to test the airflow but i wanted to make my own one to fit more fan in a package thats good for my light. But thanks anyway im gonna try some of these. If the performance is really bad, a custom built one probably wouldnt be much better.
You might be interested in the YouTube channel ProjectsInFlight, which is currently trying to build a DIY solution for fabbing simple ICs in their garage & documenting the process on YouTube.
Realistically, you can’t really compete in a market where ASML is the monopolist. Not because ASML is an ass, but simply because building just a single factory costs billions. Intel regularly invests 10 billion or more in just a single factory that doesn’t even have all the necessary tools in-house to produce a chip end to end.
Smaller manufacturers usually serve the long tail, that is rather old process nodes for use cases where bleeding edge performance isn’t needed. Bosch for example had its own manufacturing branch.
Also bleeding-edge processes mean smaller, thinner gates. That’s what gives them the fast switching speeds, but it reduces the max allowable voltage. For parts that need to handle more than 1.8V or so a modern 5nm process will just end up using bigger gates than the process is optimized for. May as well go with an older process (bigger minimum gate size) that’s better suited to switching the voltage needed. For Bosch (automotive parts, power tools, etc) they’re making a lot of parts with really big output transistors (switching 14V, 48V, etc) and not super high-performance processors.
The big disadvantage with particularly old processes is that they used smaller wafers. So fewer chips per wafer processed, meaning lower overall yields and higher price/chip. The switch from 200mm wafers to 300mm in 1999 meant the wafer area increased by a factor of 2.25! 300mm wafers also required fully-automated factories due to the weight of a wafer carrier (a front opening wafer pod, or FOUP, is 7-9kg when loaded with 25 wafers), which save on labor costs. So processes older than 1999 (around the 180nm node) are sometimes not worth it even for power electronics.
CMOS silicon logic can be chemically “printed” using photolithography and commercially available mercury lamps. From the wikipedia article, if I read between the lines those are good down to feature sizes of about 1 micron (1.0µM or 1000nm), limited of course by the accuracy of your wafer setups between processes and the printing of your lithography plates. this is the process used to produce the Intel 80486 which fit 1 million transistors on a chip. seems that laser lithography using KrF lasers can be good down to much smaller but your litho plates become the limiting factor.
so, conservatively- 1µm features would be attainable for a sort of “home brew” startup with little to no venture funding but the correct industrial knowledge. with more funding though i’d guess older laser lithography machines would be attainable on the used market and potentially usable down to 0.4µm or smaller.
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