[HN Gopher] Towards a "PCB Drone" - Making a PCB Motor which rea...
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Towards a "PCB Drone" - Making a PCB Motor which reaches 30k RPM
[video]
Author : reaperman
Score : 213 points
Date : 2023-06-25 06:30 UTC (16 hours ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| pizzafeelsright wrote:
| This is a 100x developer. I am in awe.
| ilyt wrote:
| Just passionate and talented hobbyist. It's not exactly [1] new
| invention, it's not being done because building proper engine
| is not all that more expensive, especially when you take into
| count suboptimal PCB coil design. Still need a bunch of custom
| elements too.
|
| 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/
| greggsy wrote:
| Being a developer hacker and a hobbyist are now mutually
| exclusive.
|
| Many people consider their work a hobby.
| rowanG077 wrote:
| You do realise this guy is a fulltime youtuber? He isn't a
| hobbyist. He is a professional.
| michaelbuckbee wrote:
| I'm deeply unqualified in pretty much every way to comment on the
| efficacy of this design - but _wow_ am I impressed with both the
| creativity and the perseverance of this guy.
|
| I love software, but there's just something undeniably cool about
| hardware.
| benj111 wrote:
| > 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.
| narrator wrote:
| Analog engineering is really difficult because you need to
| solve differential equations that Wolfram is unable to solve.
| Most designs were made by very smart people in the 50s at RCA
| as far as I can tell. Please tell me about how wrong I am. I
| admit the analog circuit engineering world has looked totally
| unapproachable to me even as a reasonably competent working
| computer scientist.
| agumonkey wrote:
| I love these kind of guys. Reminds me of marcoreps too.
|
| Kudos to them
| johnzim wrote:
| Wow. Probably the coolest thing to ever come out of Malta!
| topspin wrote:
| Can't help myself: going to arm chair quarterback this.
|
| 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.
| cushychicken wrote:
| Would work, but I'd estimate that it would require 4x the
| circuit area that this fella is working with. Plus adding some
| Z axis height for the optical encoder.
|
| For what he wants to do (real small, real light PCB based BLDC
| motor), I'd say his approach is right on track.
| trojan13 wrote:
| This guy's work and dedication is truly impressive. He posted a
| video [1] about his concept of a PCB drone 4 years ago and he and
| his methods have evolved so much. In addition to his highly
| specialized knowledge of designing, testing and iterating PCB
| coils, he also makes comprehensive and interesting videos out of
| it. I highly recommend checking out his channel.
|
| [1] https://www.youtube.com/watch?v=mS_qUbPTYfk
| [deleted]
| JKCalhoun wrote:
| He convinced me that the keeping the sensor on the PCB is worth
| it, ha ha.
| jacquesm wrote:
| Great work this, I wonder if the end goal is a drone why it uses
| such a strange rotor design rather than something more
| conventional (which also would obviate the need for such extreme
| RPMs).
| pests wrote:
| Is the end goal a drone? I've watched a bunch of his videos on
| his PCB motor project and I don't recall him mentioning it was
| for a drone at all. The title here on HN itself is
| editorialized to include drone so who knows.
| jacquesm wrote:
| He mentions it in the video as well.
| ilyt wrote:
| he mentions it at least https://youtu.be/NX7GHqq28uU?t=735
| trojan13 wrote:
| He mentions that the goal is a PCB drone, but also mentions
| laptop cooling as a possible application. The initial design of
| the motor is a low heat one, as the early iterations had a
| problem with overheating at low RPM.
| Taniwha wrote:
| I think he was more saying that he looked at the chips used
| for laptop cooling fans for use in his (drone) design
| bluescrn wrote:
| Yeah, I'm surprised he didn't try attaching some actual drone
| propellers to see how much thrust they'd give. There's no
| shortage of small plastic props available for 'Tiny Whoop'
| style micro-quadcopters, with 2-5 blades and in various small
| sizes.
| TD-Linux wrote:
| The size of most electric motors is proportional to the torque
| they produce - so if you can spin it faster, you can get more
| power for the same weight. There are some other factors that
| make high speed worse - for example, bearing and core losses.
| The PCB motor is a coreless motor though, so it has no core
| loss, biasing it even harder towards high speed operation.
|
| Propellers generally get less efficient with higher speeds
| though, which might be a bigger factor than any of this.
| bboygravity wrote:
| > Propellers generally get less efficient with higher speeds
| though, which might be a bigger factor than any of this.
|
| 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.
| jacquesm wrote:
| Musk isn't correct though, or maybe you misunderstood or
| misquoted him. Higher speed is only more efficient if the
| craft itself moves at a higher speed.
|
| 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'.
| jacquesm wrote:
| A coreless motor has _more_ losses, not less. That 's because
| the field isn't focused as nicely. It's just that the losses
| aren't in the core but in the air.
|
| 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.
| dist-epoch wrote:
| Could you use such a high RPM to make something jet-engine-
| like?
| jacquesm wrote:
| Ducted fan, very high power consumption though for the
| thrust.
| parentheses wrote:
| I have always wanted an ergonomically laid out electrocapacative
| keyboard. Maybe this person will one day move on to that project.
| Definitely a big impact on society.
| ilyt wrote:
| Why, did you managed to use up a mechanical one to the point
| switches failed ?
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(page generated 2023-06-25 23:00 UTC)