It's an ultrasonic mister that runs on 27 W and .9 amps. I was going to hook this up to a relay in order to
control it but am interested in using this along with:
a 24V .13A computer fan in order to control the relative humidity of a chamber.
What circuit would i need to be able to have pwm control of the fan and if possible the mister as well.
Why look for PWM fan control? When you start the mister, start the fan. When you shut off the mister, let the fan run for some time to complete the distribution of the humid air and then shut the fan off.
Why look for PWM mister control? I do not see a spec sheet to know if the product even supports PWM control. But what is the advantage you are looking for? When the humidity is too low, turn the mister on. Then turn it off.
More curiosity questions - What are you trying to do? Grow room? Huge humidor for a massive cigar collection?
I do have a humidor but it uses passive evaporators for control.
The output of the smallest model they have is a half liter per hour.
That is enough water to bring 30,000 liters of air from 0% to 100% humidity (at room temp) (if my quick googling was accurate)
What size is your chamber? What humidity level are you aiming for?
What is it that you are putting in this long term storage? (curious minds want to know)
An ultrasonic mister throws small water droplets into the air. That's not the same thing as humidity. And, ultrasonic misters make fairly-large droplets which fall to the ground quickly. (I know because I tried to make a fog machine and the fog/mist would not spread-out nicely over a large area, even with a fan.)
It's been a long time since I've studied this stuff but humidity is water vapor which is a gas (not liquid). I think an enclosed space with a sufficient pool of water will eventually reach 100% humidity. And, it will probably happen faster if you spray a mist around the chamber.
Is the temperature going to be constant? As you may know, if the absolute humidity is held constant, relative humidity increases as temperature decreases (until humidity jumps to zero at freezing).
That is small.
That mister is WAY overkill for humidity control in that sized container.
8 cu ft = 226 liters of air. 4 ml of water takes that much air from 0% to 100% humidity.
Is the container sealed? Would the air ever leave or get exchanged with outside air?
What is your target humidity?
How long is long term storage?
I have a converted curio cabinet as my humidor. I keep my cigars and some vintage ukuleles that are happiest in a controlled humidity environment.
I bought a cheap hygrometer for under $10.
I bought an Aqua Stone fur under $10.
My container is not air tight so I lose moisture to the room.
And I open it several times a week to retrieve either of those vices (if you heard me play my ukulele, you would understand
Maybe once a month I add water. It stays around 65% humidity.
Depending on how airtight your container is, you might make it much longer between checks for water fill.
It is sealed and it will be kept at a constant room temperature. I guess i need an ultrasonic humidifier rather than an ultrasonic mister from my understanding the difference is just the amount of pressure that is able to be built up around the mister the one i mentioned has an operating temperature max of 105 degrees so that wouldn't be suitable for a warm mist humidifier which was more the goal.
The aqua stone is an interesting idea but i wouldn't necessarily have control of it. The container is not completely airtight but it is close.
I guess i need an ultrasonic humidifier rather than an ultrasonic mister from my understanding the difference is just the amount of pressure that is able to be built up around the mister
I'd guess they are the same thing... If you throw enough mist into the air you will get humidity once the water particles evaporate.
But the point is, any water is going to evaporate by itself anyway until the air is saturated (100% humidity) and it can't evaporate any more, or until the source of liquid water is completely evaporated. So, you may not need any kind of "device" or any external energy unless you need to humidify quickly.
You might want to Google how humidifiers work, and how dehumidifiers work if you need to do that.
De-humidifying usually requires cooling the air (like an air conditioner) to get 100% (relative) humidity so the water condenses out of the air and becomes liquid. Then if you don't want cool air, it has to be re-heated. Cooling & re-heating the air takes a ship-load of energy!