Hello, need some advice.
I'm looking for a small motor, low torque, with a spindle rotation between 0 and 1 rpm. ,and also a way to adjust the speed. In addition to that, it has to be silent. There a lots of different geared types to be found, and also numerous boards to control speed, but no seller offers any info about the noise in dB these motors produce. Advice appreciated🙂
Steen
I'm looking for a small motor, low torque, with a spindle rotation between 0 and 1 rpm. ,and also a way to adjust the speed. In addition to that, it has to be silent. There a lots of different geared types to be found, and also numerous boards to control speed, but no seller offers any info about the noise in dB these motors produce. Advice appreciated🙂
Steen
Sounds like you might need a DC brushless type with suitable controller, these can be brought down to very low speeds with accuracy. What is the application though?
Central heating controller motor.
You can use a lot of brushless motors at whatever speed you want if you are prepared to build a controller for them. However, to get that slow you are almost certainly going to need a gearbox.
A stepper motor could be used with a flywheel - how successful that would be I don't know.
You can use a lot of brushless motors at whatever speed you want if you are prepared to build a controller for them. However, to get that slow you are almost certainly going to need a gearbox.
A stepper motor could be used with a flywheel - how successful that would be I don't know.
I'm in the start up procedure of collecting parts for a linear tracking tonearm. Finding a geared down motor, that makes "no sound" is my main focus at the moment. I figure that in order to adjust the speed only by voltage, I need a motor that is slow from "birth". On the bay there seem to be a lot of so called PWM control boards. ??
Steen
At that speed just any BLDC motor will not work. Cogging will be awful and so will torque. The motor will need to be designed specifically for that. As someone who designed motor controller for almost a decade, I can say that the motor will be overly expensive. Anything below 50rpm is difficult to design.
A stepper will be worse with cogging, and much less efficient. Although it may provide more torque.
I'd recommend a belt drive. It's not cutting edge, but probably the best for that speed if the whine of a gearbox can't be tolerated.
Does this also apply for the AC types, synchronous or asynchronous. By what means do you control speed in AC operation?
Steen
Small and none😉
Joke aside, the motor will be driving a timing belt T5, 9mm vide, and that again will drive a near frictionless "contraption", so the smaller the better.
Maybe there is no way around the gearbox, but in that case, is there a preferred type of gear regarding noise?
Steen
Yes. Although it's easier to control synchronous motors at low speed. For AC operation speed is best controlled by varying both frequency and voltage. Half speed means half frequency and half voltage. But, a BLDC motor automatically varies frequency as the inverter acts just like the commutator in a DC motor.
Tear apart a CDROM sled drive system and extract the drive motor and zero backlash gears. Add your belt and scaled up linear motion assembly. That would probably be the easiest way to get going. I guess you have the necessary machining capability to repurpose everything appropriately. Getting mugh higher performance might require direct voice coil drive, either single or multi-phase, and would be much more compicated. Depending on how you intend to set up the error signal generation and linear motion assembly you might not get high enough performance to have the DC brush motor and gear drive system be the weaker link in the chain. You could also, of course, do it the way the CD systems work, with the gear/belt drive handling coarse position and a small voice coil positioner for fine error correction, again much more complicated.
If you really wanted to nerd it out you could use the 3 phase CDROM or hard drive spindle motor in a direct drive belt configuration. You need three medium power amplifiers, either linear or switching, and associated signal processing. I'm pretty sure you would only need to bias the motor below normal running dissipation to overcome drivetrain losses. They can handle burning several watts, heatsinked as they usually are. Even nerdier would be bulding your own 3 phase linear motor. You could also build a big single phase voice coil.
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Hi Andrew
Thanks for the input, but I think this is the time to come forward and admit that I'm not the average electronic DIY'er.
As a woodworker by trade, I had hoped to just visit the Bay and buy a small AC or DC motor, with or without gears, and a cheap speed controller to go with it. Hence the questions about noise during operation. I will take your advice though, to slaughter a cd-rom drive, to see whats inside.
Steen
Thanks for the input, but I think this is the time to come forward and admit that I'm not the average electronic DIY'er.
As a woodworker by trade, I had hoped to just visit the Bay and buy a small AC or DC motor, with or without gears, and a cheap speed controller to go with it. Hence the questions about noise during operation. I will take your advice though, to slaughter a cd-rom drive, to see whats inside.
Steen
Although many different designs exist, maybe one out of two CDROMs will have a motor and gear assembly that is almost directly applicable (meaning specifically designed for this type of purpose), although it might be challenging to interface the plastic output gear to your scaled up linear drive assembly. Without some sort of fairly smooth feedback control I doubt you'll achieve satisfactory results in your application, however. There will also be a driver amplifier chip in the ROM drive for the sled motor but re-using it would definitely take at least your average electronic DIYer, and applying something else probably would too, even though that might be the more reasonable approach. Successfully completing this project would likely earn you the "average electronic DIY'er" certificate, I would say.
Somewhere in this fairly short post, you must have misinterpreted my goal. The only thing I want the motor to do, is to make the belt move approximately 10 cm. (4 inches🙂) during half an hour. Thats it. No servo, no starts and stops, no corrections along the way. A motor with some sort of reduction gear, that makes no noise.
Steen
Yeah, I actually got that pretty quickly. Compared to how itchy most people on this site get about various angles developing on their tone arm, that's Preeetty basic, especially for the usual crowd that eventually gets to thinking that linear tracking is the answer to some problem. Of course what you're thinking of doing is fine within the limits of its capability. It might be difficult to get it to play a record without breaking something, but you didn't even say you wanted to do that 🙂...
What happens if you have a record with really wide groove pitch? For example a 12min track that takes the entire side?
That's the sort of thing I'd be worried about. Every record is different. Even the space between tracks would be enough to tweak your cantilever with a constant speed drive, but if all you want to do is move something 4 inches in a half hour, no worries.
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A little more info regarding my take on a new arm.
Having had countless turntables and different arms, I think I'm capable of hearing when something works. For a long time now, I have mostly used my Sony TTS-3000 with an old Ortofon 12 inch/SPU or Denon 103. This arm is without any form of anti-skate compensation, and it still outperform anything else I've heard regarding distortion, also on the innermost tracks. So last year I built a dummy wagon, with a homemade unipivot arm 320mm long. By just pushing it along(my thirteen year old son did the pushing) it sounded awesome. And I can guarantee that the angel was not 90 degrees at any point during playback😀
Steen
Having had countless turntables and different arms, I think I'm capable of hearing when something works. For a long time now, I have mostly used my Sony TTS-3000 with an old Ortofon 12 inch/SPU or Denon 103. This arm is without any form of anti-skate compensation, and it still outperform anything else I've heard regarding distortion, also on the innermost tracks. So last year I built a dummy wagon, with a homemade unipivot arm 320mm long. By just pushing it along(my thirteen year old son did the pushing) it sounded awesome. And I can guarantee that the angel was not 90 degrees at any point during playback😀
Steen
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