Motor that makes no noise? Designing a desk fan for a recording area.

My 5' x 5' closet is my home office, wardrobe, and partial maker space, 3D printer, and prototyping areas. It's a sweet space, but gets a bit stuffy when the door is closed.

Lately I've been recording voiceovers for my YouTube videos, and I have the room pretty well tuned to have good sounding voice audio. (mainly, I just hang clothes all around). Walls contain rock wool, and most are covered with cork.

But, summer is approaching, and this place gets hot. Naturally, in the summer I work from the company's office more often. But my YouTube recording will need to take place in here.

Current setup (stays cool but is super noisy)

• Floor fan mounted on ceiling, blowing the upper air out the top of the door. This causes air exchange with the bedroom as long as the door is open.
• Floor fan mounted on the floor by my legs, simply causing air circulation at a lower level.

I typically keep the door open unless I'm on a conference call and the kids are being noisy in the rest of the house. It starts to heat up a bit, but then quickly equalizes when I open the door and the air gets refreshed.

But, recording...This winter I've been cutting all noise by cutting out all fans. That's not going to work in the summer.

Motors on hand.
I have a lot of motors on hand, ranging from small electronic DC motors, stepper motors, servo motors, AC motors, etc. But they are all loud, underpowered, or not appropriate for the use.

Then I observe the ceiling fan. It's quiet. So, my plan is to look at garage sales for ceiling fan motors to start experimenting. Maybe I can 3D print something to at least mix around the air. Or, work it out of wood or whatever. Gears would probably add noise, then I thought about doing some sort of belt drive system. But that would probably add some noise as well.

So I think I'm looking for a quiet, direct-drive motor that I can use to circulate air.

Do you have any particular ideas about what to keep an eye out for? Any pointers would be greatly appreciated.

 

You're going to be sitting at a desk recording audio with a fan also on the desk.... doing what..... blowing on you ?

I doubt you're going to design anything effective to sit on the desk. Have you looked into the Dyson wind machines. They move air quietly. Several companies make quiet muffin fans for something near you.

 

I do not care if it sits on the desk or not. I figure any vibration will be a noise issue there. My plan is to set it on the floor.

 

Your problem with noise is air movement, not motor noise.
What is keeping you cool by having a fan blow on you is the speed of the air and the speed is where the noise comes from.
You need to find a different way to keep cool....air conditioning would be the best option because having cool air moving past you would mean that you could have less air velocity for the same effect as a wind tunnel of hot air being blown around by a fan.

What would be more quiet than a fan blasting air would be a giant fan moving slowly....kind of like a giant palm leaf.

 

I agree, the problem isn't the motors. It's the fan and the movement of air. Even a forced HVAC system where the fan and motor are located far away the air coming out of the vents makes noise. Any time air moves quickly it's more prone to generate noise. Like GregH mentioned your best bet is a large fan turning slowly. This means that you will need a large area for the air to move.

The trouble is that you are working in a closet. A small enclosed space. To move large volumes of air slowly and quietly you need lots of open space. So, you might be able to move the air quietly but all that open area is going to negate the benefit of closing the door to block out noisy children.

This sort of reminds me a Universal Studios Florida. Originally it was real recording studios and an amusement park. What they found was the noise of large crowds, concerts and roller coasters could not be blocked from the sound stages. They tried sound control measures within the studios but could not achieve the quiet needed and no longer do much production there. Sometimes the environment just isn't conducive with what you want to do.

 

Thanks for the input. Air movement noise makes sense.

Yesterday I tried an AC fan speed controller box on 2 duct-style fans (became very noisy/whiny), as well as a 20" Lasko box fan. The Lasko gave hope. There was still a bit of a whine. But, it moved some air at the lowest setting and I'd be content with that. So I may try to use that, but find another motor to power it slow natively rather than introducing the whine caused by speed controllers.

I feel like there's gotta be some sort of type of motor that would work for this.

In the meantime I'll probably do some testing using some 120mm+ case fans and PWM.

 

You want to copy the setup for a fan drying out a flooded basement.

A basic 12" circular fan, duct-taped to a 25' section of uninsulated 12-inch silver foil duct.

<img src="https://images-na.ssl-images-amazon.com/images/I/81hTOORwDLL._SL1500_.jpg" width="1500" height="1500"/>

Found this worked well to deliver cool air to an attic....
Puts the fan 20' away from you

 

How about a couple quiet computer fans?

 

Unless you have a choke point along the way, the wind noise is always going to be highest at the fan itself because that's where the speed of the air is greatest. And because there's friction acting on the fan blades. Friction causes vibration and vibration creates sound waves.

And all other things being equal, a larger diameter fan spinning slower will be quieter than a smaller diameter fan spinning fast enough to move the same volume of air. I have an adapter on the outside of one of my computer cases that lets me mount a larger fan outside of the case than the case itself was intended to accommodate. It runs quieter and cooler than with the OE case exhaust fan.

And I have ceiling fans that I can't hear when they're on low speed.

 

Ok.....here's the thing.
The reason a fan only will keep a person cool is only because their body behaves like an air conditioner.

When air moves over a person it causes sweat to evaporate which causes skin temperature to lower.
A fan will in no way cause a cooling effect of any kind on anything other than with a human body.
Air movement can be helpfull to equipment because it will remove hot air from the immediate vicinity of a component but only replace that air with hopeful slightly cooler air from within the space.
A fan in no way will lower the temperature UNLESS the fan blows across something that is capable of lowering temperature, like an air conditioning coil......OR, blast air across your body allowing your perspiration to do the cooling.

You need an air conditioner, plain and simple.
Your hobby of recording needs equipment to allow it to happen.........in your case an a/c unit is as vital as a good microphone.

One thing to try that might not be too expensive is to pimp out a portable a/c unit by making an adapter to go over the air discharge and use a lager size and length of hose to blow into your space,

I would add that this is why swamp coolers work so well in some areas and not at all in others.
Areas that are very dry in the hottest months would benefit by using simple water evaporation to lower temps because the water will evaporate and doing so will lower air tempresture.
Hot humid climates not so much.

 

You have good points in your comment about how fans don't actually cool the air. Reading back through my original post, I mentioned the room getting hot, which implied that I wanted to make the room cooler....which is rightly what you're trying to help me solve based on my post.

But to be more accurate, I don't need the room to be cooler....It's plenty cool as long as fans are on to keep my body heat from generating (and staying) right around me. A simple $10 Honeywell fan has been good enough to keep me feeling cool, but loud (and too strong even on lowest setting).

So I guess I'm after something more simple than my first post implied. Fans have been great, but loud.

Bingo. I ordered 2x 120mm fans and received them today:

• Arctic P12 Silent http://amzn.com/B07GSTMRFB
• Arctic F12 Silent http://amzn.com/B0119T0D4I

They are mind-bogglingly silent. I cannot hear either of them unless I put my ear next to them. They do not put off the same amount of air as you'd expect from a 120mm fan, but they put off more than you'd expect from a silent fan.

When sitting on the desk, one fan provides plenty of air movement for my needs. There was super minor vibration noise when directly on the desk, but that went away when I put a small pad under it.

My plan:

• One on the desk
• One below the desk
• One behind my laptop to help the noisier internal laptop fan run less often

Thanks for the input, and I apologize for not more clearly stating how little air I'm trying to move.

 

It is not the motor that is noisy. It is the fan blade pushing the air that makes most of the noise.

 

My experience is...commonly, yes...and maybe the noise I'm hearing is related to bearings. I have some tiny motors that make noise without anything attached to the shaft. Certain ceiling fans are quieter than others. (maybe that's more related to bearings?)

Anyway, I'm in good shape now. I didn't need to move much air at all, and I found those 12V fans above to work really well.