Didn't think this fit in homebrew.

I have a bubble type light which you fill with water and some LEDs shine through the bottom of the cylinder and an air pump makes bubbles in the water.

The pump is 12 volts and given it is electromechanical, the pump is quite noisy.

According to the label the pump puts out a flux of 2.8 L per minute.

Is there a way to make the existing pump quiet?

If not is there a piezoelectric pump that will put out the required airflow?

Also the voltage to the LEDs is unregulated.

I'm thinking of ditching the SMD bridge rectifier, using an external bridge and filter cap so I can use a 12 volt regulator or perhaps I'll use a LM-317 so I can set the LED brightness as it currently is way too bright.

Mount the pump inside a buffer of foam rubber. Be sure it won't overheat. Simply wrapping it, seal with duct tape or a cable tie, place in a re-cycled can or metal or plastic. Like a cheese ball jar...

If that doesn't work then shopping for a fish tank pump is another option. Try Freecycle never know who has said good by to fish but the tank and the pump is in the cellar...

That one is a fish tank pump.

Perhaps I'll try the foam idea.

I'll have to drill a hole for the tubing to go through.

The existing tubing has two check valves so that water does not make it to the pump so I'll keep that in place. I can just remove the original hose that went to the pump and use a longer hose.

For the LEDs it looks like I will use a LM-317 and variable resistor to set the voltage as that will permit me to control the brightness. There is a resistor and a zener after it to ground to set the voltage to the control chip. So I'm thinking that just using an LM-317 to vary the B+ to the whole circuit will be fine so long as I don't go under a minimum value, although I could try just varying the voltage to the LEDs and using a larger filter cap before the regulator and if B+ is too high I can always insert a resistor between the rectifier and on board filter cap.

So basically what I'll have is power coming in to the board as the board controls the AC to the pump. I'll connect an external bridge rectifier across the input wires which then will go to a filter cap and on to the regulator. If needed I will then insert a resistor between the filter cap and on board filter cap to drop B+ some as I'm sure with the increased capacitance the B+ will be a little higher than stock. Plus the resistor will allow the on board cap to better filter the voltage to the board circuitry.

I'll also set the regulator so that it doesn't go over 12Vdc, although I may just use a 7805 with a zener in series with the ground lead which will provide a fixed voltage and I can just change the zener to lower or raise the voltage as needed.

Seems air pumps are all noisy, I bought a high capacity one recently from PETCO for a project and it is the noisiest thing in the whole setup running two water pumps and the air. My air-brush compressor is noisy, the vacuum pump is noisy including the one on the Foodsaver. If you find a quiet one I'd love to hear about it.

Thanks for the details on your design, I'm following along!

You're welcome.

Thee are piezoelectric air pumps which are nothing more than a big piezo element connected straight to the 120Vac line. Those are supposed to be very quiet.

But in a brief search I could not find any with the output I needed.

Cheapo fish tank pumps are all noisy. They work by something vibrating, usually at a high enough frequency that produces maximum annoyance.

The cushioning and wrapping might work, or you could try a sonic pad to set it on, and glue 1/8" rubber to the case all around to deaden the noise.

Or get a small mechanical pump instead. They are MUCH quieter

I did see a small DC pump somewhere which uses a small DC motor.

Perhaps that would work of the flow is right.

I have a vintage fish tank pump with a fractional hp motor. Mechanical open eccentric and a connecting rod to a piston in a cylinder. It sorta looks like those reciprocating stream engines. The motor drives the pump with a flat belt. I have not cleaned it up. I do think it will go "chuga-chuga" Anyone wanting to create a 20's era fish tank would be thrilled (not)...

Well, if you wanted to be creative, replicate the mechanical bellows used on manual organs but actuate them them with an eccentric driven motor. That should yield some 30" water pressure and as much liters a minute as large a bellows are made. Design in "Steampunk" tradition...Ya, I know, small

https://www.youtube.com/watch?v=1cimlqojhd8

Use a clock work motor at low RPM's
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sergneri: Look at the Hulk HP15P004SS air compressor. From Home-Depot online. Quiet & light, even lighter with aluminum tanks... Compressor suspended with rubber mounts and effective intake silencer/filter.
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Just occurred to me, your an audio guy? Yes?

A LARGE speaker with a long cone throw could effectively act as a piston to pump air. Fire with a sine wave1/2 to 4hz. Make valves from discarded plastics, pill bottles, caps and valve discs of sheet plastic. Want double action? Two speakers same but wired out of phase. Have to be heavy duty voice coils because of the sustained current. Possibly some old sub-woofers

This would use stuff I know you have on hand and your creative electromechanical skills

YMMV

Chas

Suppose I could use a speaker to drive the existing pump which is just a rubber piece with a metal arm attached to it with a magnet on the end that sits in front of a coil which is fed AC at 60Hz which thusfore makes the metal piece move back and forth.

Or I could try the existing pump on a lower frequency provided by an audio amp fed a sinewave.

Yes!
Not knowing the "pressure" requirements and space for a new design I thought a guess would not be out of order. Try different frequencies, there my be a "sweet" spot. Add a little weight to the arm to lower the mechanical resonance...

Chas

I have lots of options as I can get longer tubing and mount the pump pretty much anywhere within reason which if it is the same as the tubing for my liquid cooling I used for a game console I may already have what I need.


EDIT:

Altering the frequency does make the pump quieter, but it also decreases output.

I may try it with just water and see what it looks like.

If I like that, I may leave it like that.

If not I will find some other type of pump that is quiet.

Then again this device was made in China......

Oh that's easy; you need a flux capacitor...

(Sorry, couldn't resist!)

I just happen to have a spare. Will try it out in a bit.

You can find quiet air pumps for aquariums, but the cheapo ones are much easier to find. When I get home I'll check the brand of pump I've got on mine. Another option would be a peristaltic pump, depending on how much flow you need. I've got 5 of these guys pumps running fertilizer/chemical dosing in my aquarium: https://www.aptinstruments.com The peristaltic pumps don't move a ton of fluid, but then again I deliberately ordered the low output ones.

All I need is 2.5 L/hour air flow rate. At least that's what the stock pump says it does.

But whatever I get does not need to be expensive.

EDIT:

Looks like this may be what I need.

https://www.mouser.com/ProductDetail/Mu ... x3aTmHY%3D

https://www.mouser.com/datasheet/2/281/ ... 186478.pdf

Datasheet even includes an example driver circuit that can be run from the B+ I already have.

All I would then need is a relay connected where the pump was which will switch the driver circuit on and off.

Jun-Air's are quiet, but bloody expensive. Look for a dentist going out of business. (Hopefully not one you've gone to.)