If you can use open source, you can build hardware
redeem-tomorrow.com
redeem-tomorrow.com
Part of building hardware is making it robust enough to exist in meat space long term. That means thinking about how the humidity sensor is affected by ambient conditions (including the packaging bag, that one has bit me in the past) and having a plan for re-calibration if drift becomes too great. That means picking connectors for your wire harnesses that can handle the number of times you expect to connect/disconnect them over the course of your things lifespan. That means tuning the length of that wire harness so you can't damage it when you open the enclosure to change the battery or whatever. It means thinking about how ambient conditions affect the rest of the design, so you don't have to clean the contacts on all the wire harnesses every so often, because you didn't get gold contacts for both the harnesses and the connectors, and you live in a high humidity environment.
Don't get me wrong, I'm self-taught on virtually all of these points, it is achievable for the hobbyist. Just understand that swapping out one smart relay controller for another is pretty far from having a smart relay controller you'd even give to your sister-in-law for Christmas.
Even after reaching the prototype phase, the open source hardware is probably only useful to one person: it’s creator.
There is a big difference between making a prototype and detailing the build in sufficient detail other hobbyists can replicate it / modify / use it. Documenting hardware is substantially harder than documenting software. If the project is cool a bunch of people will be excited to jump in; some of these people have zero experience soldering or ordering laser cut parts or whatever. Supporting them is hard.
Then another step up to sell the design to other hobbyists, even just a few extra copies on Tindie.
And then a huge step up from that to selling to the general public, where suddenly FCC interference certifications are needed and the company is liable if the design burns down a few houses. There’s a reason firms making hardware have real engineers on staff held to professional standards. Plus all the cash flow and business concerns when the marginal cost per unit isn’t under 1 cent like software.
Each of these steps often involves multiple iterations of hardware and therefore lead time and cost.
Nobody is going to build it, the physical building of it is way harder than the design, anyone who could build it is too busy building their own projects that will go in the junk drawer in a week.
I would love to work at a real OSHW company, making IoT gadgets and stuff that for production and sale as polished commercial products with a software ecosystem behind them... but I lack a degree, live in Montana, and don't drive, and there are not many companies like that(And most of them are making expensive FOSS phones that don't run normal apps, cryptocurrency stuff, or glorified dev boards kinda pretending to be products)
I keep thinking that maybe high end flashlights could be the same way, I can definitely think of a few features that don't show up in your typical light, and that it might be cool to try to make a few boutique lights to sell, but my business knowledge isn't quite up to that, and I don't exactly have much desire to do a whole lot of independent work, I much prefer having an employer.
Maybe it could start as a gut replacement for an existing cheap flashlight and grow from there.
Unless maybe there's a demand for simpler lights somewhere? I tend to forget that non-LED light sources are actually a thing, but that it's pretty cool to make one from scratch at the level of hand silvered reflectors!
I'd probably be putting LED and battery temperature sensing in anything I made, so I wouldn't be too worried about safety, but it would be a mechanical challenge that would likely take some iteration to get right on the mechanical side.
There's also custom colors, flash patterns, etc
I've only been caving twice. Dimmer lights are great - but they don't need to be on a single switch. Quite the opposite, putting them on a single switch means that one _has_ to cycle through the bright option when that is not wanted.
Buttons take up space, and cost more than electronics(Not counting craptastic ones that will break in a hurry), plus you'd still need all the other driver electronics like the switching converter and the lithium protection chip.
The microcontroller is probably the most reliable thing on a flashlight, simple doesn't always mean cheap and reliable.
Also, with the right micro, a second button (with relevant environmental protection) may well be more expensive than putting that micro and voltage regulator under a big blob of black epoxy.
They have premade modules, but I'd have to do my own, since most of the point of making yet another type of light would be Bluetooth so you never lose it, can customize the modes, and it can also serve as a a motion sensor that pings your phone if someone is messing with your stuff
And there are a bunch of dactyl manuform case generators. (Which the online pcb fabs are now also offering to print in your favorite material)
I live in Montana, have a degree in an unrelated field but still work on IOT projects.
I work mostly from home or private office and have never needed to drive for course of work.
Not sure how you exist in Montana without driving.
If you’d like to move into that field, it’s certainly not easy but it is possible.
Ding!
We had a bespoke wireless entry system for our hackerspace which kinda sucked. Eventually the board switched it out for OpenPath (which also sucks--to be fair).
Why?
Support. The board can now call someone and say "We pay you. Fix this."
Support is the bane of consumer products. I really wish we had some way to counter this.
It it goes wrong, you cannot buy a new one or hire repairperson at a sane price. If it has a software side, it will probably need maintainence. If you want one, there's a large chance you might want another to expand your project.
While yes, I am able to design a reliable hardware device, unless you have a large budget it will not be immune to direct baseball bat hits or spilling epoxy in the connector. So, in practice, if you ask me to build something for you, I'll try to find a way to do it with off the shelf parts as much as possible.
Which sucks, because electronics projects are super fun, but the fun is dampened by the fact that in the end you have this completely unique irreplaceable thing that becomes a liability if you use it for anything important, which is generally tied to one application and becomes junk if you no longer need it, unlike the more general purpose off the shelf stuff.
ESPHome and Amazon modules plus 3D printing gives a pretty good balance for a lot of things. Reconfigurable, machine-soldered reliability, a prefab software stack, but still enough flexibility to build novel things.
It's not clear to me that the alternative provides these either. Just thinking about some of the appliance-type things I've had issues with lately: my oven would've made more sense to replace than hire a repair person, and my ISP-provided router is running their latest firmware which is horribly out of date...
With DIY stuff, sometimes you can't replace it because there's no equivalent, you've invented novel functionality, and bought other things that depend on it.
Like, one time, when I had a very different mindset, I made a controllable light that used a non-DMX protocol, and took power over XT60. I don't know where the special USB adapter for it is.
If "Number of direct dependents" and "Total of all dependents that are in some way customized" are more than just a few, then it's pretty nice to have standard stuff.
Building things that are effectively clones of what you could just buy isn't that interesting to me, but making novel things comes with future unpredictability.
I like to look for projects where there either just isn't any commercial thing at any reasonable price that would work, or the thing is non-critical, or there aren't many design decisions in other things based on the custom thing I'm doing.
> but the fun is dampened by the fact that in the end you have this completely unique irreplaceable thing
I suppose people have widely varying tolerances and desires for unpredictability in daily life, some people really seem to like actually using unique tools, self hosting, customizing their computer with original scripts, etc.
The hardware design is the last line of defense before you can do real-world damage.
Things like fuses, ESD and surge protection, watchdog timers, often get overlooked in a hobbyist or even open-source design... it takes (sometimes hard-won) experience to know when these things are required.
That all said - I have written firmware for things that other people have wired and it's quite fun!
Although I'd imagine you got lucky here because IIRC this particular's chip voltage drops with temperature a tiny bit so technically the one that starts to heat up would drop voltage, letting other pick up the slack
You can prototype some hardware. I’ve looked into trying to build some stuff that goes beyond what a little prepackaged MCU dev board can do, and I can’t wrap my head around it. Too much stuff involved that in no good at.
Software is deterministic and quite easy to reason about. It either works, or it doesn't. Hardware relies on actual physics, and even minute changes can be the difference between working perfectly fine and not working at all.
A lot of hardware design is based on rules-of-thumb and institutional knowledge. Learning those as a hobbyist is incredibly difficult, and most of the time you essentially end up cargo culting what everyone else is doing - and there is no guarantee that everyone else is doing the right thing either! It is really easy to end up wasting hundreds if not thousands of dollars like this.
This is exactly why companies like Adafruit have become so big. They take care of all the hard part, and provide the hobbyists with essentially a bunch of lego bricks which neatly click together. The only thing you have to do yourself is... the software.
That's probably also why all software is 'bug free' ;)
But seriously: both software and hardware have their unique challenges. But those can be overcome and just like software hardware can be 'unit tested' by breaking down circuitry into manageable chunks. Adafruit is a success simply because they fill a need: the ability to create bespoke gadgets without investing lot of $ or learning a new skill. The market to programmers, not to hardware people, though I'm sure there is some overlap as well due to the convenience. But those skills are not substantially harder than software skills, they are just different.
I'm kind of lucky: I got into software through hardware rather than the other way around. To me software was an infinite parts budget (bounded by RAM limitations, usually). Hardware was a running expense, computing a one-time expense (or so I thought, hah!). So I simply got more mileage out of my pocket money and Saturday job earnings by saving for a computer rather than by spending it on various hardware components.
Good starterpoint: and FPGA evaluation board, such as Digilent's offerings. Those pack enormous power in a tiny setup and will teach you a ton of very valuable skills.
If that looks like a hit you can decide to deepen your knowledge.
As soon as there's a non-trivial analog element - anything frequency-dependent, resonant, exceptionally resistant to RF interference, or switching significant current - you absolutely do need that math.
You can model resonant filters with DSP, but you still need to understand z-plane digital models. It doesn't hurt to have some idea how they relate to s-plane analog models.
Cook-book tinkering is plenty fun, but you really can make things explode or burst into flames if your project is switching and/or carrying any significant load.
Stuff exploding or bursting into flames I've seen exactly once, on one of the most trivial circuits I ever built: a small boost converter for a windmill to charge batteries in low wind conditions. It worked extremely well. Until I disconnected the battery for service and then the boost converter kept on increasing its output voltage until the capacitors let out the magic smoke. Other than that stuff occasionally breaks. Oh, and if you do do RF stuff: beware of RF burns, that is a real risk, coils and capacitors in high power RF circuits should be treated with proper respect.
I'd be much more wary of Lithium-Ion batteries than analog stuff and buck-boost converters are cheaper to source as complete units than to build yourself (though you definitely can if you want). Your typical hobbyist isn't going to start off by building themselves an large inverter or a HVDC interconnect. They're going to build amplifiers, other audio gear and maybe some measuring kit or digital devices. Sound generators, function generators and so on.
By the time you reach the stage where you need to design a resonant LC circuit you'll have picked up a lot of working knowledge and some of that will tell you what bits to avoid and what bits you can probably handle.
I know plenty of HAMs that know enough math to be dangerous but they usually would not be able to do really complex stuff without access to tools (though I also know some HAMs that definitely would be able to do really complex stuff, they also have the corresponding higher level license).
Let's not pretend that everybody that builds electronics for hobby purposes is a math wizard, it just isn't true. Though it definitely doesn't hurt to have a basic understanding of RC and LC circuitry and to understand how to use op amps and other interesting components like that. Applying those is vastly different from designing them from scratch.
Also: quite a few people have a ton of fun just building kits and slowly expanding their knowledge and there is absolutely nothing wrong with that. At the highest levels you will need that math, but there is plenty of interesting stuff to be done lower on the ladder. HN is the last place where I would expect such gatekeeping.
Compared to software it is a costly hobby though, and it also occupies more space beyond just a laptop. And it can be quite messy.
It's extremely different, imo.
Releasing buggy software to prod: no biggy, hotfixed in a couple of hours
Releasing buggy hardware: recalls, mass customer dissastifaction.
I learned that the hard way when I automated the heat lamp that I put in my chicken coop. Having to noodle around with screw terminals while being pecked at by an angry rooster was not a great time.
Yeah they are more expensive than running printer in your garage because they need to earn money too but it's not like the price grows with volume
A box that might cost $0.25 if injection molded might be $25 if 3D printed.
Some simple things that you shouldn't have to learn the hard way (but most people do):
Make sure your wiring contacts are electrochemically compatible. Gold-to-gold is safe in almost every household environment.
Strain relieve every wire. Solder is not meant to be structural.
Every circuit component degrades over time. Heat, humidity, and dust accelerates that process. Make a plan to mitigate the ingress of each, and a plan to account for that degradation.
Learn to design simple breakout-board carrier boards. The best breadboard layouts are still worse than a mediocre PCB, because the PCB doesn't have flywires to catch on literally everything.
Make sure you include mechanical support points for your designs, and pick the right size and material for your mechanical supports.
All of this to say, your hardware thing is a thing first, and an expression of your software/firmware design second. If it cannot physically survive being that physical thing, the elegance or resiliency of your code is meaningless.
- Don’t run data lines and power lines right next to each other (electric signals flow through a field surrounding the trace/wire, not in or on the metal itself)
- PCB pros avoid right angles for the same reason. Bevel your corners. (You see examples of this on every board if you’re not sure what I mean)
- Verify PCB traces with a multimeter before soldering components to it (or if it’s been assembled by the PCB manufacturer, verify everything before powering it on for the first time)
If your design suffers from the consequences of this, your reach has probably exceeded your grasp. Its true that you can get noise from sharp corners, but unless you're running SPI at maximum speed, it probably won't cause any bugs in your project. And if you need to run that fast, you're going to run into other, less straightforward signal integrity problems too.
PCBs with right angle trances look ugly though. So I might still judge you for it, but only if you also wear white before Memorial Day.
So, I do not use 90 degree turns for this reason, if not for the EMI reason.
That whole article addresses the myths surrounding right angle traces pretty effectively.
0. https://www.nwengineeringllc.com/article/right-angle-pcb-tra...
Not true. The electrons certainly do travel within the copper. The movement of the electrons generates a magnetic field around the conductor, but the electricity does not "flow through a field surrounding the trace/wire". The electric power absolutely does flow through the metal itself.
>PCB pros avoid right angles for the same reason.
This is a myth except maybe in very rare cases. Most hobbyists aren't ever going to have a problem with right angle traces.
https://www.nwengineeringllc.com/article/right-angle-pcb-tra...
>Verify PCB traces with a multimeter before soldering components to it (or if it’s been assembled by the PCB manufacturer, verify everything before powering it on for the first time)
You should be sure that your design works before sending it to be assembled. If you designed the PCB with proper software that does analysis between the schematic and the PCB design, then there really shouldn't be any surprises that would require you to verify any PCB traces with a multimeter before soldering components. Sure you may have had it manufactured by a crap PCB company, but it's unlikely, PCBs have gotten really easy to make. Software like KiCad if used properly make it practically foolproof to design a PCB that matches the schematic.
Designing the schematic is another matter though, it's very easy for a noob to get that part completely wrong and testing PCB traces with a multimeter is not going to fix that.
>or if it’s been assembled by the PCB manufacturer, verify everything before powering it on for the first time
Not sure what that would accomplish. What are you going to test? Many components can't even be tested unless power is applied. Seems like you're suggesting superstition more than practical knowledge about hardware design and manufacture.
Look inside older stuff that predates 3d printing and cheap mold tooling, just to avoid the trap of everything being made the same way. In my case, since I'm interested in music, I've looked inside things like guitar pedals and amps, which often solve the problem of making something that's robust, but that can be made profitably in short runs and small shops.
Get a hold of the McMaster-Carr catalog, in paper form, and leave it in the bathroom. An old Digi-Key catalog if someone still has one.
Lots of other good in-the-trenches reporting of hard-won knowledge in the blog. Many epoxy resins shrink significantly, for example. That may or may not be important for your project. The blog is not super condensed but it's worth reading, especially for seeing the evolution of design and construction practise from the early years (2011) to now.
There's a book, now somewhat dated, on the Protection of Electronic Circuits from Overvoltages (lightning strikes, or fridge motors, for example): [2] TVSes (transient voltage suppressors) are still in use, however. Even varistors.
Connectors are the bane of every electrical engineer's life. There are more designs of connectors than of any other category of component, and probably there are good reasons for all of them to exist. I haven't got any good references for this topic though.
Other things like fuses, fireproof insulation on on your power cables, physical design such that prying objects can't touch high voltages, and so are about protecting the rest of the world from your projects.
Rod Elliott's web site [3] is a mine of information for beginning to intermediate hobbyists. It's focused on analog, audio specifically, but when you get down deep enough, everything in electronics is analog. you need to know about resistance, capacitance, and inductance, earthing (grounding) layout, and other similar topics.
1. https://thecavepearlproject.org/2023/03/17/waterproofing-you...
2. https://store.doverpublications.com/0486425525.html Available on Amazon as an ebook.
Composition is great for prototyping and small-scale production. As you level up and learn about optimizing BOMs and DFM, you will start to swap out MCU boards for your own designs; you'll see how that $10 I2C rotary encoder can be replaced with $1 worth of resistors, capacitors, a Schottky diode and a hex inverter.
Anyhow, I came to say that with companies like JLBPCB and PCBWay offering 3D printing and CNC services, you don't even need to buy a 3D printer to get started.
Heck, with https://wokwi.com/ you might not even need prototyping components.
My gut tells me that the software market that serves hardware engineers isn't nearly as creative or ambitious as that on pure software and even devops or infrastructure.
Huge opportunity there.
A lot of the work of a hardware engineer is reading and interpreting datasheets and trying to separate the wheat from the chaff. The low-hanging fruit which can easily be automated is the easy part of the job, and writing the input data for the automation ends up taking more time than just manually doing it yourself.
I have dabbled into writing some software extensions for KiCad, and some turned out to be very useful and now save me quite a lot of time. However, every time I tried to be "clever" and solve a seemingly easy problem, it ended up not being worth it in the end.
There are some interesting companies out there that I am watching, like flux.io. The problem there is that none of these companies are working on creating open-source tooling, so their endgame seems to be getting acquired by Altium, Cadence et al.
I fear a future where doing even regular PCB designs will be gatekept by the Cadences and Synopysyes of the world, akin to how IC design is today. At least we have KiCad right now, which is getting really powerful and is fantastic for doing PCB development work.
The idea is I didn't find an existing water-well sensor for my purposes, so I am building my own. Final price of BOM probably 20EUR. Time spent learning and tinkering - hundreds of hours. Cost of stuff I had to buy to support all this, probably somewhere around 500EUR now. (printer, connector crimpers, cables, MCUs, solder boards, sensors, battery holders, electronic components, filament for the printer, soldering iron, etc). It has all been worth it.
I love CAD but man do I hate 3D printing. It's a type of device that seems to have been invented to illustrate Murphy's law that "anything that can go wrong, will go wrong".
The print nozzle gets clogged. Every. Time. The filament breaks at the worst possible position and requires some disassembly to remove. The printing stops for no reason in the middle of a long print. The plate is never exactly even. You forgot to leave the wire spool with enough free spinning and when the machine pulls on the wire it makes the spool fall, itself pulling the whole machine down with it as a vengeance.
And of course, it takes hours.
I have been much more lucky with external providers that you can send your file to, and they send an object back. It's often expensive and takes even longer than doing it at home (days vs hours), but there's no price for peace of mind.
For example, an industrial solution to some of the problems would be a checklist based inspection of the printer between every task, but this would be incredibly tedious.
Software that has to directly interface with reality also has these problems.
As metallurgy goes, casting is very old tech. I won't say it's the simplest thing, but it was simple enough that pre-industrial people were figuring it out, which says something about complexity.
Lathe work starts out with cylinders or polyhedrons, which
But we only carve shapes out of polyhedrons, or build them up from nothing. It seems more likely that for complex, concave or knotted objects, we should be using low resolution additive printing and high resolution subtractive printing in combination.
We may also need CNC machines with a an additional degree of freedom. Perhaps not a fully 'prehensile tail' but the ability to tilt the cutting head to say 45º would probably reduce the gap between additive and subtractive manufacturing's achievable shapes by quite a bit.
Although, to be honest, my bigger problem is probably just simply not having a use case which I could use a self-built hardware project for. I don’t feel like I’m missing or lacking anything in my life or at home that could be fixed with a hardware project.
Additionally, I usually want the absolute best solution to a problem that I can afford. Commercial products have satisfied me well so far. My mindset about this is that if I can just pay someone for a product that solves my problem, I will gladly do so instead of scratching my head with a self-built project (I consider my time more valuable than anything else).
So I guess what really needs to happen to make me actually dip my toes in the hardware soup… is to have an annoying enough problem that cannot be solved with ready-made products on the market (either because they are bad or outright don’t exist).
At the cost of being old and slow. I wouldn't be throwing roses to Prusa after they effectively ceded the market to everyone else.
For $200, you can get a Sovol SV06 that's a smarter iteration on the MK3/MK3S (while also being open-source both in hardware and software); for $500 you can get a Bambu P1P that's much faster and has better vertical integration through the slicer (and for $100 more than that you can get a P1S, which is high-temp ready while also doing all the same things as the P1P).
I used to do microwave communications repair in the army. The most painful part of my education was basic soldering. I couldn’t solder for the life of me. I have the finger dexterity of a brick (which is to say none at all).
A few years I took a comprehensive career aptitude assessment, which included testing finger dexterity. I thought I’d done really well after taking the test. I was informed I scored in the bottom 5%. If I became a surgeon, my malpractice insurance would cost more than my annual salary.
1. https://jlcpcb.com/capabilities/pcb-assembly-capabilities
Which probably makes more sense than designing hardware components for most applications.
But it's not the same as designing circuits etc. and the title is a bit misleading as far as that goes.
I’m not there yet but I’m working on transitioning from software to hardware… so I want to get there eventually!
If you just need an enclosure for a product there are ready-made ones that you just drill and cut as needed. And for anything to do with sensing or automation look into industrial PLCs (automationdirect.com is the cheap supplier) before you start re-inventing the wheel.
Ughhhhhhhh operating system updates, internet issues, test kit from China that we had to use a specific version of cracked Windows XP and still do live support in broken English at midnight.
Hardware is hard - Never again!
I don't trust myself to build something that I can leave unattended and won't catch fire. How does one get over this?
When it comes to stuff failing in general at hobby level you either burn something instantly (plug the power to an IC backwards and see the magic smoke go away) or it just heats up VERY VERY FAST!
I once plugged an external 5V power to a development board that was already USB powered but I didn’t know it… it started smelling like something was burning within a few seconds and I burned myself by touching it instead of pulling the heat camera :-)
Very wise words. Coming from sw/hw industries I probably could work around heat pump microcontrollers without too much hassle and I well know the pain of physical components messing up your debug process. But such industries rarely rely on open source, and all the OSS I used was for personal projects. That is definitely a big limit for my future work opportunities! :/
https://www.microchip.com/samples/
https://www.analog.com/en/support/customer-service-resources...
https://reddit.com/r/electronics/comments/1qvcr2/how_to_prop...
Sampling is intended to get a sample so the company's expectation is that it will eventually result in an actual order. This will obviously happen when sampling to companies, and sampling to EE students means those students are more likely to choose your products when they enter the field.
Sampling to hobbyists doesn't really have any return on investment, so once they started getting thousands of requests they just shut it down. These days you are just expected to order low-quantity items from their distributors.
The feedback loop is just very long. Few weeks to get PCB unless you pay a lot extra to get it in few days.
And even if you own a 3d printer for mechanical parts that's still day of printing
I've built a device that times my espresso machine and controls the grinder. I build a 4x wifi socket just because it was fun. Getting high quality temperature and humidity values or co2 is unbelievably easy, cheap and fun.
Coupled with Homeassistant you can spend a lot of time and have a lot of fun. I did at least.
> the Sentinelese appear to have consistently refused any interaction with the outside world. They are hostile to outsiders and have killed people who approached or landed on the island.
https://en.wikipedia.org/wiki/Sentinelese
But more seriously I would say there is a difference between intentionally and incidentally using open source software.
I run Linux and FreeBSD on multiple machines. I use open source software intentionally.
My girlfriend runs Windows on her laptop. If we look closely I am sure we will find open source libraries being used both within the OS, and within other pieces of software that she runs. But all of that is incidental. She is not interested in software and that is fine.
My mother and my grandfather both use LibreOffice. But only because I installed it for them. So neither my grandfather nor my mother really are intentional users of open source software. It just happened to be the case that their grandson/son (me) knew about LibreOffice and installed it for them, so that they could use it to write documents and to open Word documents that other people sent to them.
This approach certainly gets tried enough. I'd say it has some issues, though.
Currently printing the bottom of a custom osu! pad for the third time after a couple goofs.
Absolutely a blast though, especially coming from doing purely software. Even if you're just doing prototypes, highly recommended.
Or even "You don't need to learn svelte!" (I love Svelte but statements like that are not helpful).
Would I need specific parts from the manufacturers?
Would dissecting the existing component give enough detail for me to remake without the (I assume proprietary/hidden) schematics?
But you really do not want to be experimenting with custom control unless you know exactly what you're doing. Aside from the risk of nuking food and/or accidentally bypassing the door switch and microwaving yourself/partner/kids/pets/etc, most uwaves have huge power capacitors near the controller board.
An unplanned encounter with one of those can kill you.
Here's a sample circuit. It's not super-complex. But there's a lot to go wrong, and it's really not a beginner project.
https://www.electronicsforu.com/electronics-projects/microwa...
Remotes are basically the same with (usually) an IR transmitter, more buttons, and no dangerous power switching. It's not all that hard to clone one, but the hard part is making the tiny physical buttons and inventing a better UI.
Most devices already use pretty standard components, a microwave for example would have “something” to switch the thing on and off. It might be a solid state relay or something like that. Maybe it has multiple, one to control the fan, light, motor to turn the things around, and the thing that emits the microwaves.
But once you figure out what signal is needed to start those (a bit of intuition and a multimeter might suffice) you are off to the races!
One you open a few house appliances it’s easy to see how they optimized for cost, so you seldom find fancy protocols or components unless they are absolutely necessary.
In a toaster over for example, you might find a temperature sensor and it would likely take a bit of fever engineering to calibrate the temperature to the voltage output (I’m assuming that is a cheap analog sensor instead of something that spits a digital I2C signal for example).
So yeah! It shouldn’t be too hard to hack your devices :-)
When you are trying to improve an existing product, you first need to figure out what the existing part is doing. This is going to be incredibly difficult because you do not have access to the original documentation. Often it involves proprietary parts for which zero documentation is publicly available, and you are going to need quite expensive tooling to figure out what it is doing without those docs.
In general I do not really think this is viable to a beginner for anything beyond completely trivial product. A microwave is a really bad idea due to the voltages and currents involved (you can easily end up killing yourself). A TV remote is probably doable, but mostly because you can do that without opening up the remote at all and just need to look at the (often standardized) IR signals coming out.