[HN Gopher] How Servo Motors Work
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How Servo Motors Work
Author : kaycebasques
Score : 108 points
Date : 2025-04-03 19:18 UTC (1 days ago)
(HTM) web link (www.jameco.com)
(TXT) w3m dump (www.jameco.com)
| dcrazy wrote:
| I've noticed that distributors (Jameco, Mouser, etc) have a
| surprising number of introductory education articles. I've seen
| this pattern on websites for car dealerships and HVAC installers,
| so I assumed it was for SEO purposes. But electronic parts
| distribution seems like a much more niche audience; why bother
| with SEO?
| sokka_h2otribe wrote:
| Some may be application notes from the manufacturers.
|
| Jameco also supplies mid level engineering firms, so similar to
| application notes. Think automation integration company buying
| xyz specialty robotics controller.
|
| I think of mouser as more like digikey, so I don't really know
| why they would have similar educational information above the
| level of PCB board component. But, they may also have business
| in the low-quantity higher margin business.
|
| Tldr: not seo. Customers actually need to know about the
| product
| iancmceachern wrote:
| Exactly, as one of their target audience I'm not searching
| for them, I know who they are. I go to their website
| regularly and articles like these are how I find out about
| new stuff and how to use it.
| analog31 wrote:
| I think it's just a tradition in the electronics world to write
| and publish hobby and educational articles. It dates back to
| well before the the Internet. People enjoy this interaction,
| and the distributors give them space for it.
|
| People like HVAC installers -- I've seen most of that on
| YouTube, where there's a chance of monetizing the content. I've
| repaired nearly every appliance in my house, thanks to blogs
| and videos posted by strangers.
| dcrazy wrote:
| Indeed. Vancouver Carpenter got me through a minor drywall
| repair job.
| larrywright wrote:
| He's fantastic. I still suck at drywall work, but I suck
| way less after watching a bunch of his videos.
| MisterTea wrote:
| It brings you to their site as well as advertises a specific
| component or range of components from a manufacturer.
|
| The Digikey articles I've come across are well written. This
| article however is artificially inflated using SEO style
| writing. I mean after they supposedly explained servo motors
| you'll find this ugly sentence further down: "Still, how does a
| servo motor work?" I mean holy shit man, do you even care about
| your writing or the subject? Likely not. And really, the
| article is so light on details its barely technical and only
| talks about the RC servo. This is pretty much junk.
| hydrogen7800 wrote:
| This reminds me that Monoprice used to have a "knowledge base"
| for many of their products. I don't remember if they were just
| written directly on an item's page, or if there was a link to
| the relevant article, but it was very informative.
| tomcam wrote:
| Is it this? I didn't know about it until your post.
|
| https://help.matterhackers.com
| cbhl wrote:
| If I recall correctly these pages are useful for teachers and
| students, and Jameco has relatively high-touch education sales
| (for example, their kitting program:
| https://www.jameco.com/Jameco/workshop/education-
| center/educ...).
|
| I want to say that I remember seeing this page in high school
| in the late 00s, although the Internet Archive only seems to go
| back to 2012 for this exact URL.
| HeyLaughingBoy wrote:
| Electronics distributors have published educational material
| for decades. Knowing how something works and how to choose the
| best option reduces their support burden and itself a form of
| marketing.
|
| Omega Engineering used to (still does?) publish a set of
| absolutely massive hardcover catalogs on sensors and industrial
| controls that contained detailed tutorials and theory of
| operation. In some cases, they published entire books devoted
| to teaching you how stuff worked. Their Temperature Sensors
| Handbook always had a place on my bookshelf for many years.
| brcmthrowaway wrote:
| I tried using a hobby servo but it was very loud with a high
| pitched annoying sound. What servos are better?
| bilsbie wrote:
| How does it hold its position? Does that take energy?
| Animats wrote:
| Only if there's some force pushing it away from the goal
| position.
| dehrmann wrote:
| I don't think servos normally do this, but it's possible to
| have self-locking worm drives.
| Animats wrote:
| It's about how radio control toy servos from the 1970s work.
| Annoyingly, those pre-computer dumb devices with no feedback
| output still dominate the low end of mechanical output devices.
| namibj wrote:
| Makes me wonder if the generic servos of the described kind are
| really close enough to the performance a cheap-class servo can
| have, or if modern advances in monolithic power stage ICs could
| allow a servo free of sliding movement (no brushes, no wiper
| potentiometer (maybe a capacitively coupled differential
| sensing of angle, or the tricks of the cheap digital calipers
| with their iirc nonius-like scale read through several parallel
| tracks of non-touching capacitive electrodes?), instead just a
| clever chip digitally controlling a brushless electric machine
| using the feedback sensing available to it).
|
| Being able to run an even just very simple digital controller
| allows things like severely dropping negative feedback gain at
| a resonance frequency of the larger system. And so much more.
| Animats wrote:
| The nice thing about using a potentiometer for position
| sensing is that you don't have to home the thing.
|
| There are lots of alternative sensors, but most are bigger,
| heavier, or more expensive. If 1% precision is good enough,
| pots are fine. The next step up is Dynamixel servos, which
| have a nice daisy-chain digital interface, encoders, about
| the same form factor as toy-type servos, at about 10x the
| price.[1]
|
| [1] https://www.robotis.us/dynamixel/
| HeyLaughingBoy wrote:
| Yeah, but they're _cheap_ and basically trivial to use. Cheap
| enough and trivial enough that they can replace solenoids in a
| lot of use cases.
|
| One of my most amusing applications was the client who put an
| R/C servo on the choke cable of a carbureted generator motor
| instead of spending more money to buy the fuel-injected
| version. Servo cost about $5 and we were already measuring air
| temperature and had a PWM output available.
| mkarliner wrote:
| hmm. this looks suspiciously AI generated to me.
| viraptor wrote:
| > Understanding the technical aspects of a servo motor and how it
| works
|
| I don't feel like the article explains that at all. They explain
| the control signal and what the servo does as a result. The "how"
| in between is completely missing though. How is that pulse
| translated? How does the feedback work? What are the safety
| mechanisms involved?
| relaxing wrote:
| That's because the control circuit is hidden in a monolithic
| IC. If you're really curious, here's a datasheet for an old
| fashioned design with a block diagram and theory of operation
| described that should give you some hints.
| https://www.meditronik.com.pl/doc/plus/zn409.pdf
|
| If that sort of thing interests you, there's a whole field of
| control theory to study.
| gsf_emergency_2 wrote:
| https://lastminuteengineers.com/servo-motor-arduino-tutorial...
|
| Interactive diagrams + code
| MarkSweep wrote:
| I think this is a pretty good overview of how motors work and
| how you can write algorithms to control how much torque they
| generate by varying the PWM:
|
| https://www.actronic-solutions.de/files/actronic/FTPROOT/Fie...
| arbitrandomuser wrote:
| I just want to put this hack here which enables the toy servos
| with a very high accuracy and repeatability
|
| https://youtu.be/ECLrLupFW10?si=dQPSq-hjMTaVGuQS
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(page generated 2025-04-04 23:02 UTC)