Question about ultrasonic mist maker

[SentinelAeon]

Hello,
I am using a cheap ultrasonic mist maker for certain thing. My goal is to get as much mist as i can with it. In order for this i need the answer to two questions:

1) What would be the optimal distance between top of the mister and the water level, meaning how far under the water it needs to be to get the max output. If this cannot be answered then how would i go about testing it. I can visualy try to assess it testing different depths but visual inspection of mist is not very accurate.

2) This mist maker has holes in the bottom of it and it has very tiny legs, so that if its on the bottom of water box, there will always be about 1mm of space for water to get in. Does this distance matter ? Because right now i made a system where the mist maker will actualy be floating a few centimeters under the water top. That way no matter how much water i have in the box, it will still be working. But does that negatively affect its performance ?


My goal is to get as much mist i can with given Wattage. This module uses about 12W and with added fan i turn about 0.25L of water per hour into a mist. I would like to increase this amount as much as i can with as electricity usage. I attached an image of the mist maker element.

 

[SentinelAeon]

I have a question, Pommie, @Dr_Dogg, danadak, Externet. Right now i am running 1 mist maker, running on a 24V 1A DC adapter i found online. The mist says it uses 24V 1A but in reality it uses 24V 0.5A (tried different mister, different power supply, the included power suply is capable of 1A, was tested). Anyway, now i would like to use 4 misters so for that i will need more power. To keep things simple i was thinking of using a different stronger power suply and then use a step-up or step-down, thats capable of at least 24V 4A. Do you see any problem going this way ? I mean, 24V is 24V right ?

 

[Externet]

If the recommended supply for one mister is 24 Volt 1 Ampere and you plan to feed three more equal misters with a single supply, your planned 24V 4A capable supply is correct to feed them all together.

 

[SentinelAeon]

Thank you. There shouldn't be any problem by using step-up or step-down right ? I mean, it doesn't change anything so long as its 24V and cam supply enough current ?

 

[Pommie]

There shouldn't be any problem by using step-up or step-down right ?

Where does step up/down come into this?
You simply need a 24V 4A supply.
If you use a step up converter from (say) 12V then you'll need an 8A supply.

Mike.

 

[Dr_Doggy]

the rule of thumb is that you need to match volts , but have extra current on the supply side, so ya 24@4 is fine, but from my exp it may just be easier to keep each mister with its own wall wart, and cheaper too, plus then you need to think about splitting and Marettes and whatnot, simpler and just as clean to just tie the wires together with cable ties.

 

[SentinelAeon]

I was thinking of using one of a bunch of 20V power suplies i have. I need about 96W (even though usage is 0.5A per mist maker, not 1A as stated), maybe 20V 4.5A could be a cheap safe option ? And obviously i would need to raise that 20V to 24V with a step-up.


Bonus question: Does anyone have any idea what would happen if i connected mist maker to 20V instead of 24V. Would that mean it works slower or not at all ? As for using 28V instead of 24V i prolly already know the answer, it would burn out.

 

[SentinelAeon]

the rule of thumb is that you need to match volts , but have extra current on the supply side, so ya 24@4 is fine, but from my exp it may just be easier to keep each mister with its own wall wart, and cheaper too, plus then you need to think about splitting and Marettes and whatnot, simpler and just as clean to just tie the wires together with cable ties.

Not cheaper because i already have a stronger power suplies that i cant get rid of and those 24V 1A i would have to order. And step-ups i have many of those, each can handle 2A so i would use 2 of them, got them for cents.

Do you have any explanation why everywhere its stated that the mist maker uses 1A at 24V, but when i used killawatt it actualy used 0.5A ?

 

[Pommie]

Do you have any explanation why everywhere its stated that the mist maker uses 1A at 24V, but when i used killawatt it actualy used 0.5A ?

Maybe it needs 1A at startup.

Mike.

 

[SentinelAeon]

Hmm, or maybe they just posted false data. But if only startup is the problem then i could easily use a couple of capacitors directly on DC input to solve this. Maybe i could measure input amps at startup though i doubt my multimeter is fast enough to register it. The reason i am so persistent on this is that i got like 10 or more 90W power suplies that i prolly will never be able to sell and it would be nice to be able to use them. Power suplies have some caps as far as i know to be able to handle some spikes in themselves and if 1 dies after years, i can live with that. Would be a shame to go on buying a 120W psu and not use those 90W i got lying around.

 

[Pommie]

Try putting four misters on your 90W supply.

Mike.

 

[SentinelAeon]

I will do that ! Thank you. And i might throw in a capacitor or two, for that startup juice.


Btw non related question regarding the mist maker. I first made a prototype box and put it 1 meter away from me. In minutes i was shaking cold. Then i did another box, similar vent, same mist maker, smaller exit. And the wierdest thing, no chill from the mist maker, and visibly less mist. So i kind of opened the lid and suddenly lots of mist was coming out again. I tried to see what was going on and there seemed to be lots of waves of air inside, meaning, air didnt exit the box in a straight line, it seemed to be mixing inside, circulating, doing waves. So, could it be possible that it was actualy blowing mist right back into the water and sides of the box and therefor less mist came out ? Because when i opened the box, mist maker was doing perfectly fine, but when i closed it, like half of mist only came out, compared to my first box.


ps: this mist maker has holes at the bottom. What are they for ? Because as far as i know, piezo element on top is the one doing the mist ... water comes on top, it shoots out. What are the holes on the bottom for ?

 

[SentinelAeon]

Dr_Doggy Pommie This mist maker has holes on the bottom. What are they for ? I am asking because i made a float so that mist maker is floating in water at the correct depth (this way when i pour more water, mist maker will still work because it rises). Is it possible that the bottom of mist maker has to touch the floor ? It has tiny legs, like 1 mm. I included photo of mist maker from both sides to help you answer.

 

[Dr_Doggy]

i think bottom hole is to refill water,
what i really remember is that if it is too deep the evaporated water recondenses.
the part marked in red is the safety sensor and needs to be submerged,
touching the floor is not a requirement

 

[SentinelAeon]

Yeah, i wondered about those holes. Because i always thought the top white part vibrates ... and water naturaly always is there since its submerged.

 

[SentinelAeon]

I have a question. Obviously, running those mist makers at over 24V will destroy them. But what happens if you temporarily run them at lower voltage ? For instance if you power them up at 3V then adjust the step-up all the way to 24V, can that lower voltage damage them ?

 

[DrDoggy2]

mist goes out the top and replenishes through the bottom, it would prolly still work if you plugged the bottom, but would reduce flow since the water would then need to replinsish through the top

2)ramping volts is prolly not good for it, depending on the controller it could cause the controller to struggle, and may not be nice for it. better to use on off switching circuits to control it.

 

[SentinelAeon]

DrDoggy2 i meant to do it only once since i am using stepup controlers for which they say its better to have load on them before turning them on and im to lazy to look for some random resistor. Also, i need the mist maker plugged in to adjust the step-up since there is some voltage drop. So for instance if i set 24V on stepup, that will be 23V when i plug in the mist maker. If i overcompensate and go for 25V, it will be 24.5V on mist maker. I always try to be 0.1 or 0.2 above the voltage, like 24.2V instea of 24V.

 

[DrDoggy2]

That will be fine then.

 

[Pommie]

Why does the output of the step-up vary?

Mike.

 

[SentinelAeon]

Pommie It's a very cheap step-up and depending on how much load you put on it, it has a slight voltage drop. I plan to test the step-up this way too, see how much it can handle and for how long. Later i plan to buy a better step-up