Electronic Controller for Ultrasonic Humidifier Project

Hi All, thank you in advance!
I am a farmer in NSW trying to start on farm Cheese and fermenting chamber for home business. Making best efforts to learn PCBs etc but struggling.

I would like to design my own Ultrasonic Humidifier that provides ultra fine mist to maintain best practice humidity levels within the chamber. The humidifier itself is a Stainless Steel or Food Grade water reservoir *( approx size of tissue box) in which the transducer is mounted on bottom. All other controllers, electronics, water solenoid is located separately from this unit.

I have the Nebuliser ( TDK Product used in most commercial humidifiers). I can create the steam; however, I need a electronic controller that can:

  1. Receive a command from the main refrigerator controller to turn the humidifier on and off. This is through the humidity sensor ( inside cabinet) via humidity differentials programmed in Main Fridge Control panel
  2. Control the automatic water top up via 3 x optical sensors mounted in the wall of the tank, via a 12Vdc water solenoid. a. Low Low level Alarm= switch off power, b. Low Level: open water solenoid, c. High Level = turn off water solenoid.
  3. operate a 12 volt fan
  4. Operate with 48 Vac (out)and 12 Vdac (out) power supplies

Note: I have previously had the system operating using cheap E Bay float type sensors, however, I have gone to optical digital sensors that are small, no moving parts. The optimum water level is 4-5 cm so other type sensors are to bulky. Note: I am using a baffle to create minimal water disturbance inside chamber.

I am looking some support in the build of the controller. I live in NSW.
Ultrasonic Humidifier.pdf (140.1 KB)
Thank you Paul

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Hi Paul, welcome to the forum!

Sounds like a cool project and one that could work with quite a few different microcontroller options. Most of the core Arduino boards will work with a 12VDC supply and should have enough digital input and output pins to control the devices you are interfacing with. The Arduino Uno is the flagship go-to board for most projects using arduinos.

How will the Main Fridge Control panel communicate commands to the new microcontroller?

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Hi Trent and thanks for the welcome.
Yes it is a great project; however, a struggle for over a year of hits and misses (ha). I just don’t have a background in electronics. As briefly mentioned, with the help of a neighbor and some Analog controllers ( Ebay) and floats, we have had it up and running and works fine. Since I have switched to the optical level sensors, everything has gone down hill due to lack of Arduino knowledge, multiple power supplies, etc.
In answer to your question, my local fridge tech set this up and I believe, he installed the Humidifier sensor within cabinet and then wired the same main fridge control panel output to the transducer power supply ? ( 48 Vac). Basically on/off in sync with the humidity level % differentials pre-set on the main fridge controller. For example, As soon as the humidity levels dropped 5 points, the humidifier started and the other supporting 12vdc devices ( i.e , axial fan, float vales, water solenoid etc) ran as well. Once humidity levels reached target level everything switched off. Also, not mentioned, the fridge technician also wired up a heater element inside cabinet (240 volt) with the controller for de- humidification . Kind Regards, Paul

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Hi Paul,

I think an Arduino microcontroller that interfaces between your digital sensors and the fridge controller unit is what you will need. We just need to know a bit more about how we will communicate with the fridge controller and what is switching and supplying power to your output devices.

I’ve thrown together a quick diagram of what I’m thinking your system might look like.

All of the outputs we are controlling will need a relay, the Arduino digital outputs don’t have the capability to serve as a power supply for a pump or fan, they are just a low power signal.

I am assuming that right now your fridge control unit has relays connected to it or built-in.
Once we know more about how the fridge control unit is switching your outputs currently, then the Arduino may be able to just send commands to the fridge unit to do the switching, or we may need separate relays and we take the fridge control unit out of the loop altogether.

Hope this helps,
Trent

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Here is a much better worded explanation of using relays with the arduino Uno.

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Hi Trent, Wow, thank you so much. Your diagram itself provided excellent information. Thank you.

I will definitely read the tutorial. Please find below and attached some additional information. Thank you for your patience.

  • The Main fridge controller is an EVCOJ53692. It is specifically designed to enable several functions as we have highlighted ( humidifier on/ off, temp differentials, de-humidification ( heater), etc. I believe the fridge control unit has relays connected to it or built-in.

Your diagram makes general sense to me. FYI, see below the two different types of optical sensors I have on hand or considered:

The following picture is of a commercial humidifier water reservoir ( upside down) showing the Transducer mounted in base and the transducer boards mounted underneath. I am only using 1 x transducer and planned to dislocate the board from the unit ( central location)

I believe the white plugs to the right are water level sensors?

The majority of quality commercial humidifier manufacturers use this particular Nebuliser. The specs says both 48 AC and DC but the PCB board indicates AC?

Also, the units generally have all power supplies and peripherals ( including water solenoid) within the unit. This unit is quite a large one. The board gets very hot.

The humidifier is mounted outside or inside the cabinet with air flow channelled towards the internal cabinet air flow.

Thanks Paul

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This message has been marked as Public on 17/06/2021 1:25 PM.

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Spec Sheet.pdf (602 KB)

Transducer Data.pdf (170 KB)

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I didn’t notice the spec sheets you attached at first, those will be super helpful. The fridge controller in the spec sheet is a slightly different model but should largely still be relevant.

That spec sheet confirms the relays are built into the fridge control unit, we may still be able to use them by getting the microcontroller to send signals to the fridge controller.

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Hi Trent, thanks mate!
I never considered the Main Fridge controller had that relays and potential to use these elements might be an option. Is there anything other info I could provide at this stage. Once again, I appreciate your time, professionalism and expertise.

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Could you double-check this number for me? I’m on the EVCO website and can’t find that product.
The spec sheet you linked is for a EVJ506N2, in all likelihood they are similar but it would be good to have the exact spec sheet.

That spec sheet is pretty dense and will take a bit of time to get my head around I think.
It would be nice to use the fridge controller to control its built-in relays if we can since you already have it. Getting external relays and controlling everything from the Arduino is also an option.

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HI Trent, thanks and sorry for the confusion. I thought the one I sent you was correct. Not sure why there are some subtle differences with the codes? However, My invoice for the controller was

  • EVJ536N2VX3XXV

https://www.evco.it/en/index.php?id_category=16172&controller=category&id_lang=2

New spec sheet attached. Having trouble downloading the installation manual which is listed on web page.

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Evco Controller -EVJ536N2VX3XXV.pdf (1.05 MB)

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Hi Trent, I was wondering if you had a chance to review the controller. Thanks Paul

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Hi Paul,

Sorry I hadn’t had a proper sit down yet and looked at the controller, I expect I’ll have some time this afternoon to have a proper read through and pitch and idea.

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Hi Paul,

Your fridge control unit seems like the right tool for the job with all the relays you need built-in to handle the humidifying, dehumidifying, running the fans, heater, etc. Can you confirm that this is all working currently and the only missing link is something to control the water level within the humidifier?

If that is the case to keep things simple, I’d be inclined to use an Arduino to only control the water level. So 3 digital inputs connect to the water level sensors, and one digital output connects to the water solenoid.
The catch is what to do if the low-low-level sensor gets triggered as you would potentially need to shut down the fridge controller or send it a command to shut down the nebulizer.
There are two digital inputs on the fridge control unit but I’m not sure if they could be configured to shut the unit down as it wasn’t exactly designed for that.
My other idea to send commands to the fridge control unit is to use its door-open digital input switch. I know that can be configured to activate an alarm, but I’m not clear if the door-open condition disables humidifying.

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Hi Trent, thank you for your email and time to review the information and controller. Much appreciated. I hope to answer your questions accurately.

Can you confirm that this is all working currently and the only missing link is something to control the water level within the humidifier?

At present, the electrician hooked up the EVCO controller to relevant power supplies and condenser unit. Inside the coolroom is the Humidity sensor and Temp Sensor. I believe this info feeds back to the EVCO controller.

Temperature

  • The evco controller temp was set via the controller with a + /- 2 deg differential. For example, If the temp within cool room rose + 2 degrees above set temp the condenser would turn on. When the room reached 2 degs lower than the set temp the condenser would turn off. Currently working.
  • If the Cold room reached 3 degrees lower than the set temp, the sensor would turn on the 240 volt heating element until it reached the low differential. Currently working

Humidity and Dehumidification:

  • Humidity: The EVCO controller was set at a prescribed level ( for example 80%) High Differential set at 85% rH and low 75%. Outside these differentials the controller would start the 48 Vac transducer. Currently working but not in sync with sensors, water solenoid and safety power shut off.

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Hi Paul,

Thanks for clearing that up I think I have a good picture of how everything is working now. Special thanks for the diagram, I do love a good diagram.

Will the new system control the fan or is the fan currently always on when the nebulizer is running?

The only missing link currently is the safety shutdown command to the fridge control unit.
I suppose you could start on the remainder of the system and start with getting the Arduino to monitor the water level sensors, trigger the solenoid, and set an alarm or light to indicate when the safety shutdown should trigger.

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Hi Trent, thanks for feedback,

Will the new system control the fan or is the fan currently always on when the nebulizer is running? The 12v fan housed with the humidifier chamber needs to turn on same time as nebulise. The fan is just assisting the mist out the outlet. Obviously fan turns off when the nebuliser turns off

The only missing link currently is the safety shutdown command to the fridge control unit. In this case I suggest we don’t want the fridge controller to shut down ( including condenser) BUT Could the Arduino send a power shut off signal to shut down the 48 volt power supply when the water level sensor hits LL. I assume the EVCO controller wont know anyway the levels of the water…Thoughts?

I suppose you could start on the remainder of the system and start with getting the Arduino to monitor the water level sensors, trigger the solenoid, and set an alarm or light to indicate when the safety shutdown should trigger.

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Hi Trent, thanks again. In addition to my last, once the plan is figured out, is there an option for me to pay for the development? I am not sure how all this works. Thanks and have a great weekend. Paul

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Hi Paul,

We run this forum to inspire and support makers and hobbyists in their creative projects.
For commercial development we usually refer to an engineering consultancy like SAPHI here in Newcastle https://core-electronics.com.au/commercial-support

Ah perfect, we don’t need to worry about it then.

Not a bad idea, this isn’t how you’d normally control something but since we will have more trouble interfacing with the fridge control unit we may be better off having a second relay inline to inhibit the nebulizer power during a Low-Low alarm state.

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Thanks Trent, hope you had a good weekend.

With the help of my electrician and some further guidance I would love to give the project another attempt. I have been going round in circles the last 18 months and have been bogged down. You have provided and redefined the concept much better. I would certainly appreciate further support. This form and your help has been excellent. Thank you.

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Hi Paul,

I had a great weekend tinkering away on some projects that had been on the backburner for some time, somewhat similar to your project here.

Having an electrician help with assembling your project is a great idea, they will know best practice wiring and enclosure specs to avoid accidents that might damage something. Most electricians don’t dabble in control system design but we can help you with the code and control system here.

I think the next step is drawing up a good diagram clearly showing the two controllers and how they will interact. Basically, just a pictorial of what we discussed last week to get your electrician caught up with the plan.
The only unorthodox part will probably be the output of the Arduino to disable the nebuliser where we will have two relays in series to act as an AND gate, so both controllers are needed to enable the nebuliser (and either can shut it down).

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