We have a small test project based on AI, and we need a few Voice coil motors.
Something like 45W which generates a force of ~25N (stroke of ~1.5 inches).
Voice coil motors advantages
- the force is almost linear whatever the position of the stroke is (unlike solenoids)
- reversing polarity reverses the direction as well (unlike solenoids)
However, looking for such pieces of hardware on the Net yielded only two retailers, the price per motor is ~
$1000 
which seems to be way overpriced(?)
Any recommendation on where to search voice coil motors? Or is it that hard to make one myself?
You might try old hard disk drives.
High pole count brushless servo motor and rack-and-pinion?
Back in the dim past, I recall that there was a line of sub-woofers made with stepping motors. Because the frequency response was limited to rather low frequencies, an agile stepper motor could keep up with the waveform.
@+sync did not mention a frequency response requirement so perhaps we must assume it is higher than a stepper motor can handle???
With modern very-high strength permanent magnets, it is much more practical to DIY you own solenoid solution these days.
Or if only "bang-bang" (vs. linear) is required, perhaps pneumatic would be a better solution?
You might try old hard disk drives.
25N force?
Yes. Think older. The 14" variety.
@xygor oh yes! way older indeed! but even at the time, the head had to be very light to accommodate fast positioning - and they probably didn't need 25N - not sure about this ; but that's a good idea I keep in mind.
@TCWilliamson would you mind to provide a rough price range for that AVM90-30 to have everyone informed - sites that give freely and directly the price are convenient . and a 30mm stroke would be a bit short
@Richard Crowley actually the requirements that were not mentioned before: have to be quiet (ie not a stepping motor) and very fast reaction (ie not a stepping motor) - would you have any recommendation on where to find such voice coil "motors" for powerful subwoofers? The DIY approach is interesting, need to find a good tutorial!
thanks everyone
@xygor oh yes! way older indeed! but even at the time, the head had to be very light to accommodate fast positioning - and they probably didn't need 25N - not sure about this ; but that's a good idea I keep in mind.
@TCWilliamson would you mind to provide a rough price range for that AVM90-30 to have everyone informed - sites that give freely and directly the price are convenient . and a 30mm stroke would be a bit short
@Richard Crowley actually the requirements that were not mentioned before: have to be quiet (ie not a stepping motor) and very fast reaction (ie not a stepping motor) - would you have any recommendation on where to find such voice coil "motors" for powerful subwoofers? The DIY approach is interesting, need to find a good tutorial!
thanks everyone
I'm afraid not, you would have to ask for a quote from our sales team.
Since we don't know the application, we still don't know whether you are going for a "bang-bang" application (end-stop to end-stop), or whether you are looking for some analog/linear positioning (and what are you using to sense the position?)
A voice coil is simply a moving coil in the presence of a magnetic field. There are enough high-strength magnets available online that you could easily assemble the magnet necessary for your specs. And winding a coil is pretty easy on a lathe or drill-press (or DIY lash-up) It may well be more difficult to provide the mechanical support to ensure smooth linear motion. Those old hard drives used monster 4 inch voice coils and magnet assemblies big as a loaf of bread. And they used cast aluminum carriages with ball-bearing wheels and machined rails to run on. Dave did a tear-down of one of these here....
Interesting video, and amazing voice coil motors! 8 ohms at 20V, that's 50W! More than enough it seems.
The project part is based on visual sensors (camera like) and a lot of software to analyze and control moving objects - that need to be dealt with very quickly and with the right force.
Just a prototype, and at the beginning a unique voice coil motor would be fine, to setup and refine parameters.
Such hard drive will probably be hard to fine, the DIY is probably the best option to make the ideal force/stroke at a low price.
Since we don't know the application, we still don't know whether you are going for a "bang-bang" application (end-stop to end-stop), or whether you are looking for some analog/linear positioning (and what are you using to sense the position?)
A voice coil is simply a moving coil in the presence of a magnetic field. There are enough high-strength magnets available online that you could easily assemble the magnet necessary for your specs. And winding a coil is pretty easy on a lathe or drill-press (or DIY lash-up) It may well be more difficult to provide the mechanical support to ensure smooth linear motion. Those old hard drives used monster 4 inch voice coils and magnet assemblies big as a loaf of bread. And they used cast aluminum carriages with ball-bearing wheels and machined rails to run on. Dave did a tear-down of one of these here....
I serviced those kind of disk drives in the 70s. The amount of mass and the speed obtained was very impressive. They could easily lop off a finger or two if one wasn't careful. The power supplies needed lots of capacitance storage as there had to be enough energy to command an emergency retraction in the event of several error types, including loss of AC mains, to prevent very expensive heads(20)/platters (10). Even blank platter packs cost like $1,200. Whole two 2 drive unit (we called them pizza ovens) cost more then the home I bought at the time.