What is a "digital" motor?
Dyson keeps going on about their new "digital" motor. What is a digital motor? How can a motor be digital, if it is inherently analog? Is it just marketing doublespeak?
@Dean, People easily found the information, so I assume it was easy to come by, but when you want to discuss someone's claims it helps if you link directly to their claims. This will improve the quality of the site directly. Directly quoting the claims with links will provide best results. This way in 20 years people can still understand the context.
http://en.wikipedia.org/wiki/Reluctance_motor Digitally controlled motor would be more accurate.
Unfortunately the term digital seems to be applied inappropriately to all sorts of things.
Here is a good video from the EEVBlog taking Dyson to task for their "Dyson digital motor".
Here is Dyson's take where they say "Dyson digital motors use digital pulse technology, spinning at up to 104,000 times a minute"
Then again, most switches to turn a motor on or off are digital, binary in fact ;-)
So basically it's a standard brushless motor? Why do they say it uses an iron core? I thought you needed a magnetic core for high power applications.
"And as the carbon brushes wear down, they emit carbon particles, which is bad for the environment." What a bunch of nonsense.
My gaming computer has 8 fans in it, that's 8 digital motors right there, and strangely none of them say Dyson on them.
So what - Dyson have taken a typical hard drive motor (for example) that hasn't changed in how many years? and put a fan on it...? Big innovation...
@Majenko, Use the vacuum and you will change your tone. Helluva great vacuum, I could care less about their marketing, my carpet is clean : )
Our intelligence has been severely damaged, at times, by the likes of marketing schemes the world over.
There's no answer here - neither of the links you provide give the answer.
Turning something on and off does not make it "digital". Switch-mode power supplies are not digital. Class D amplifiers are not digital. Just because something outputs square waves doesn't mean it's digital.
"Digital" means data or information being transferred in the form of discrete symbols. As long as a symbol is received without error, the signal suffers zero degradation, unlike analog which is incrementally corrupted by noise and distortion.
Those symbols can be represented by on and off pulses, like in digital logic, but also by any other scheme you can think of, like phase shifts of a sine wave, or by frequency shifts of a sine wave, or whatever. They're all digital.
Be careful here, remember that Morse code is digital. Not all digital codes contain error correction or check bits, so just because it is digital does not guarantee perfect reception.
I didn't mean that it guarantees perfect reception. I mean that, if there are no errors, the signal is transmitted with zero degradation. If you transmit it through the same channel many times it will not degrade, while analog will, even if the noise floor is very low.
As an audio guy I've had the Class D is not digital argument far too many times. I keep feeling the entire thing may have been avoided if they simply skipped 'D' in topology naming...
@Mark: Yeah, or just call it a "PWM amplifier". I guess PDM amplifier or other modulations schemes would also be considered Class D?
@endolith: Digital signals are generally discrete in both the time and voltage domain, while most analog signals are continuous in both domains. The term "discrete-time analog" can be used for signals which are continuous in the voltage domain but not the time domain; I don't know of any nice term for signals which are discrete in the voltage domain but continuous in the time domain. I think your definition of "digital" is a good one, though I'd use phrase it "received and retransmitted through similar channels" to emphasize that repetition isn't for redundancy, but rather for relaying.
@supercat: I'm thinking of things like PWM, which looks like a square wave, but is actually analog. It's not resistant to noise or interference, and the timing between transitions is continuous and important.
Things like like PWM and FM can be analog or digital, depending upon what's generating or receiving the signal (in particular, whether the receiver will "care" about details finer than the resolution of the channel). My point was that the time and voltage domains can independently be continuous or discrete; making one or the other discrete can offer considerable advantages even if the other is continuous. In a true digital signal, both time and voltage are generally discrete (though the sampling rate and number of levels may be large relative to the semantic content).
@supercat: Yes, there can be analog signals, digital signals, or discrete-time signals. But digital signals are not necessarily discrete levels. FSK is digital, but consists of sine waves. Yes, the important thing is whether the receiver "cares" about the analog values, or only about the discrete symbols they represent.
Agreed, it's all marketing. I do a lot of work with ac motors, all the stuff they talk about on the website is comical. The motor itself is not digital, the power regulator to the motor is, but who cares. It's a vacuum, not exactly a precision machine. As far as the materials, they probably just lower the over all weight (the motor is probably the single most heaviest part) to reduce shipping cost. And one last thing, carbon dust isn't going to hurt the environment.
They could be referring to the control method as well. Most motors are controlled with PWM from an external source, but if there's a built-in driver then you might command it with serial protocols or DIO instead of voltage. I've seen 'smart motors' like that. It looks like there's electronics integrated on to the Dyson motor, so that might be it.
But yeah, marketspeak.
So it's the control method that's "digital". Quite a different matter from the motor being digital. I guess it's a bit like the way cars are sometimes described as having "electric windows" or "electric wing mirrors" - electricity is used to move them but there's nothing electric about their functioning as windows or mirrors!
According to this article stepper motors are sometimes called digital motors because they are driven with pulses which control the degree of rotation.
I'm sure Dyson choose to call the motor a digital motor in their marketing because it sounds more sciency, and that seems to be a bit of a trend these days... at least they don't say it will give your carpet up to 90% more shine.