If the pump doesn’t heat up much wrap a pillow around it. Also try using regular elastic bands, the smaller they are the better (as long as it still holds for a reasonable time).
What you are building is a mechanical low pass filter – passing 20 hz and below, filtering anything above. Adding mass to the pump and elasticity to the mounting is the key.
Paul.
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We have a
mechanical mass-spring system == rubber bands + motor mass
acoustical mass-spring system = air compliance inside big pipe + acoustic mass inside small pipes, more known as a Helmholtz-resonator.
The resonator is heavily damped with a mixture of lamb-wool + synthetic fiber.
(If you try with 100% synthetic fiber, the effect will be isothermal compression but not much absorption.)
3. Any sufficiently advanced technology is indistinguishable from magic.
TheCunningFellow
Jul 5 (9 hours ago)
This is how I got to 48dB BTW
https://www.aliexpress.com/item/DC24-Brushless-10W-12L-min-High-Pressure-Micro-Diaphragm-Pump-TC-50A/32490419755.html
> The ID is 3.75mm the OD is 6.3 to 6.8mm (minor and major diameter of the barbs). Nothing seems to be 3.175mm
Then how do you fit the tube? My Liteplacer kit tube has ~4mm ID and ~6mm OD.
_m
Work very well > 1kHz
Showing which parts comes from surface acceleration of the body, and not acoustical conduction from the acoustic openings.
Both plots is with the fan inside running at full speed to cool the motor.
2 low-cost solutions is to instead use sand or bitumen in-between the big pipes.
Sand has the nice property that it eats a lot of energy moving it around. I will go and by a small bag of sand I think.
To make the spectrum follow the Equal-loudness contour, I need to kill the region at 550 Hz.
Anything sine-wave below the threshold, a young human with perfect hearing cannot hear.
Well you need some noise or your wife will not belive that you are working! ?
I use kind pumps of various sizes in some of my equipment.
They are fantastic quality and I buy direct from knf.
I have some of the smaller ones so I can look on Monday how quiet they are.
However I use some very large by comparison pumps and I use a silencer from rs components.
It makes a massive difference.
I'll lookup the part numbers on Monday.
Peter
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> it makes life so much easier I can not see how people work without it
Good point. It turns out that way some times.
Just as an example: Before I had the heat gun I was not aware of how often and for what diverse purposes I would use it. Like for gluing stuff with hot glue. One can practically “reflow” and “rework” stuff almost like with solder. Life saving for first-of-a-kind contraptions.
_Mark
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Colling fan
Pump with rubber bands and mount.
Goes into black pipe.
2 standard plastic pipes. Sand in between. Hot melt glue to seal.
The objective is a 10$ silencer, if you have a small 3D printer.
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