Towards a “PCB Drone” – Making a PCB Motor which reaches 30k RPM [video]
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The product is some Tomogachi/Pokemon type thing.
I love software, but there's just something undeniably cool about hardware.
Personally I just like going lower level. I like Ben Eater making whatever out of a few chips. I've set my line at asm else I'd just end up making a whole computer out of transistors or sand.
I am very interested to know this. Do you have any resources on this development work done by RCA and how it has shaped the modern world?
https://patents.google.com/?q=(analog+circuit)&assignee=rca&...
But then again my only analog experience is just IO stuff for digital, I've never done anything interesting in pure analog, I think if you're a real analog enthusiast you might get bored of what you can do without math.
Don't get me wrong, he's a genius, but everytime he transitions into "anyone can do this stuff!" It rubs me the wrong way
The envy I feel when I see these guys with such equipment is enormous. I really would love so much to have a loaded electronics work bench especially oscilloscopes, LAs etc. and of course the time to actually play with it. :-(
Sure, you can get a free trial through any of the altium.com/yt/<channelname> sponsorships, but if you want to continue to have access after the trial it's merely $12,000 for a perpetual license or $355/mo for a subscription. Just absurd for anyone who isn't using this professionally.
Some people pirate it - there are loads of Russian forums selling cracked license keys; be aware that the software with the cracked license will still 'phone home' and earn you a call from Altium legal in a few years with a lawsuit and your public IP/home network MAC addresses, especially if anyone with a legit license opens the files you produce. But it's just not better than Kicad, with the exception of the push router. It's sluggish, and constantly gets more sluggish... "Please wait a moment" is a blatant lie, it should say "I hope you saved recently". You get used to hitting Ctrl+Shift+Esc and force-quitting DXP.exe, because it hangs for 30+ seconds when you try to restart it the normal way. The scripting language is atrocious, but everything is built on layers of decades-old scripts. And when you run any tool that uses a script, you lose the ability to undo past that point. I hear it's no longer written entirely in Delphi, with the infamous "Ignore segfaults" option... but I've long since left for Kicad, when my education license ran out and resetting my VM stopped working I looked at the writing on the wall and ran.
I mostly do industrial automation - PLC, CNC, and robotics projects - and prefer to buy parts off the shelf for 10x the (actual) price of building my own PCB to avoid being the only person on the planet who can support that machine, but sometimes the shelf just doesn't have anything to do what you want. And Kicad has been perfect for that.
Lots of profession electrical engineers that I’ve met pay for personal copies of Altium for their moonlighting work, however. One short contract per year more than pays for it.
Hobbyists stick with KiCAD though, which would suffice for this work. Altium is mainly used by contractors for compatibility with their corporate counterparts.
Kinda like coilguns, a fun hobby to fuck around and optimize but overall there is a reason it's not really commercially done all that much.
But helluva edition to resume if he ever decides to work in industry!
- [1] https://pcbstator.com/
Many people consider their work a hobby.
Him showing his engineering projects on Youtube and getting himself paid like that means he is a professional. The main difference between a hobbyist and a professional is simply whether you get paid for doing it.
But that is beside the point. Whether he is paid for "quality of his electrical engineering output" doesn't matter. He is paid for doing engineering, which means he is a professional.
Propellers generally get less efficient with higher speeds though, which might be a bigger factor than any of this.
Core losses by the way are typically a different kind of loss, they are eddy currents resulting from the fact that the stator laminates are not infinitely thin.
Unless operated at lower air-pressure (higher altitude) then higher speed is generally more efficient.
Source: Musk interviews about why electronic very high altitude aircraft make sense in a lot of ways (faster, more energy efficient, potentially cheaper, less polluting). But only after battery densities are improved in the future.
To explain a bit further: a prop is at its most efficient when it has clean air to work with and that only works if the craft moves forward at least as much as one prop's worth of air in the direction of motion. Less than that and the prop will encounter it's own backwash. This is the reason why variable props exist, to ensure that the prop has enough 'bite' rather than that it just churns the local air. So at low revs you run a higher angle than when you go faster and towards the tips of the prop the angle gets flatter as well.
Which more or less defines the range of a variable prop, once the tips are nearly flat there is nothing more to gain. Another important factor is blade count. A single blade is theoretically most efficient because it can run at the highest RPM before the blade encounters it's own wake again, but there are balancing issues and vibration issues with low (<3) blade count props. And in practice the efficiency gains are offset by complexity, weight (a single blade needs a counterweight) and drag of that weight. Two is common enough though because it is easy to make a sturdy two blader prop. Three is optimal from a longevity and maintenance point of view, and a offers very good efficiency.
And I think you meant 'electric', not 'electronic'.
He's got it completely backwards from what Musk said in that interview, see my reply.
If you're going to cite sources like that at least get it remotely close to right.
"For aircraft, or just generally, you want to move a large mass of air slowly. So you can reduce the velocity component of kinetic energy, which goes as the square. You want to move a large amount of mass slowly, not a small amount of mass fast... So, the way you make aircraft engines more efficient is you move a lot of air slowly. Like big fans, basically, big slow fans work great. Small, tiny. fast-moving jets, are very inefficient." - your favorite billionaire, in the exact interview you're inversely misquoting. (JRE #1609 last ~12 minutes is electric planes)
* https://www.youtube.com/watch?v=ip641WmY4pA (quick demo)
* https://www.youtube.com/watch?v=Q76dMggUH1M (building)
Since sine waves work better at low speed consider a DAC driving small power amps. A dual output 8 bit DAC could easily generate the frequencies involved and allow tailoring the curve with RPM. Closing the loop would likely be easier and more effective with an optical pickup of some sort: that would do away with back EMF problems at different speeds and increase precision for better tuning, which is crucial for efficiency.
At some point off-the-shelf motor drivers are insufficient.
For what he wants to do (real small, real light PCB based BLDC motor), I'd say his approach is right on track.
A DAC would involve a larger PCB. A small DDS (si5341) would be pretty good though at 3x3mm. Three phased channels could drive the six inductors far beyond any feasible speed here.
> Plus adding some Z axis height for the optical encoder.
A SMT photodiode and IR LED could do this off the edge with some fiddling, which appears to be in ample supply here.
Not to mention that you can't adjust the drive phases of a DDS with I2C fast enough to be of any use for BLDC. Once you add in a sensor/feedback element, it definitely wouldn't have the latency performance you'd need for BLDC.
I haven't considered using a DAC with a motor before, but that strikes me as extremely inefficient, which is one of the design considerations. You're basically going from a simple class D amp to a class A one. The motor has plenty of inductance so you may as well PWM it for efficiency.
A brushless motor is essentially 3 large inductors. They act as a filter to PWM drive signals, which means that the resultant current is fairly continuous - much like a class D audio amplifier uses the inductance of a speaker to create smooth sine waves.
There's no need to add an intermediate smooth analog stage (which is what a true DAC would give you) - because then either you drive a linear amplifier and have massive power losses in the drive transistors, or drive a class D type amplifier (which turns your nice continuous signal back into PWM to the drive transistors) and you've just added an unnecessary digital -> analog -> PWM sequence.
When you want good low speed control of a brushless motor, the gold standard is a high resolution encoder (often magnetic) coupled with "field oriented control" - which is essentially using your 6 drive transistors to create a magnetic field which is exactly 90 degrees ahead or behind your permanent magnet field. You can use entirely digital PWM switching to create that field, as the natural filtering effect of the motor coils smooths it out, and the resultant driver & motor is highly efficient.
The much simpler "6 step commutation" discussed in the video can give almost as good control at low speeds, but the magnetic field you create in the coils isn't necessarily perfectly aligned with your motor's magnetic field, which means some of the magnetic force generated is just pulling on your bearings and not driving the motor. That means overall efficiency is slightly less and the torque at low speeds is variable depending on rotor position.
Kudos to them
Every chip has capsense peripherals these days. Even the ones that don't have capsense peripherals secretly do if they have an ADC, that can sometimes be easier to make more reliable than the hardware(Although those might be better for larger areas).
Not sure what exactly you have in mind for it so I couldn't give any specific numbers, but I would guess $150 to $500 max if I was doing it, maybe a bit more if you want any super fancy addons, and that's including making the case.
But you'd probably have to specify a layout yourself, otherwise that would be the hard part to actually get that one excellent. The rest is all pretty trivial well known engineering, making the layout actually feel nice to a touch typist especially would probably need someone who's very tactile and in tune with the subtitles of doing things by touch.