I'm just an enthusiast, I want to build a simple fan operated by a thermostat.

Tonyr1084

Joined Sep 24, 2015
7,852
this product I have in mind already exists
Then why the secrecy?
the circuit need be little more than a waterproof thermistor probe, a potentiometer, a comparator with little hysteresis, and a switching device
Already mentioned that. Also asked the TS about their skill level for building electronic circuits, but I guess he must have gotten lost on other points within this thread.
When the resistance is low, the fan should go off and the fan should run when the resistance is high.
Sounds backwards, unless I'm missing something you're trying to convey.
 

DickCappels

Joined Aug 21, 2008
10,153
You're right. Its one of those things, try as I might, it tries to come out backwards. Restated properly:

In the fish tank when the water is too cold the bi-metallic strip closes (low resistance) and electrical contact so the heater will be powered. When the temperature gets high enough the strip opens (open circuit) to shut off the heating current. A fan to keep something cool would operate in the opposite manner.

Just think of it as a very nonlinear thermistor with hysteresis.
 

Tonyr1084

Joined Sep 24, 2015
7,852
While researching something unrelated to this thread I came upon this video. I haven't watched the whole thing yet but I wanted to share it with you. Particularly at eight minutes 36 seconds. A temperature sensor that can be used in a wet environment, like what you want to do.

 

Thread Starter

Albertoinbox

Joined May 29, 2020
52
Hi guys, how are you all doing?

I'm sorry I left the impression that I came, took all your information and ran...

Actually, I got enough information to have to take a good step back to process all that information.

It took me some time but finally, I was able to put it together. Check it out and tell me what you think please:

 

Tonyr1084

Joined Sep 24, 2015
7,852
Looks good. Been a while, but didn't I get the impression you wanted to run two fans where one comes on and if a second is needed it will? I take it you've plugged a temperature sensor into the controller. That should be included in your video.

If you want two different fans coming on at different temperatures then all you need is a second device set up the same way, only adjusted to a higher setting.

Good job so far.
 

Thread Starter

Albertoinbox

Joined May 29, 2020
52
Thank you for your feedback!

I'm sorry I gave you the wrong impression. I presented the project initially with only one fan just to figure out the wiring, I could then just tap in more fans if I needed. I do like your idea of fans turning on in sequence though, it isn't right for this application, but perhaps for a future project. Thanks for presenting the idea and how to go about it as well.

I decided to go with two fans so it could produce the cooling effect in "half the time", since its more important to keep the noise on for a shorter period of time than having it louder. But I still have to test the performance and reason how many fans and what size fans is best and if its best to have less but larger fans or more smaller fans. The lowest profile possible is desired. For now these two fans are my best starting point bet.

The secrecy is because I'm making a major improvement on an existing product. Until its possible release its just good sense to keep it to a minimum. Nothing personal, just the way things are I guess. I'm a student and I'm doing this independently, meaning on my own. I will be happy to share it with you first hand.

Im sorry the video isn't very clear, I was so happy I wasn't very systematic. This perfect module comes with a sensor probe, isn't that fantastic? Its even replaceable and waterproof. Although I must find a way to insert it in the water in some kind of housing that will protect it from being in the water permanently. I'm thinking of a TPU housing, but I'm not sure if it would act as insulation, I need a material that will eventually transfer the real reading from the water to the sensor, I dont want to have to compensate for it. Materials and ideas are always welcome.

Next step is designing and fabricating the housing for the product. Cant wait to have a first prototype. I will post this and further developments.

I will probably make a digital version to compare cost and performance. What you guys think, digital or not? Why?

I will also make another version of this product containing a new feature that has a similar system running independently. Making a product that closes a maintenance cycle by itself, when today you must you different non intra-communicating devices.

Heres a shot of the sensor probe that I didn't focus on in the video:

IMG_9774.jpg
 
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Thread Starter

Albertoinbox

Joined May 29, 2020
52
Look at this amazing product, its exactly what I had in mind in the beginning. Its even USB powered. Too bad the temperature range is not quite right.

Its not even expensive, though I would prefer to build my own rather than incorporate it. If he could do it and keep it sleek and cheap maybe I should stick with this concept, what do you guys think? I'm good with the mechanical version also.

https://www.acinfinity.com/componen...set-thermal-trigger-for-usb-fans-and-devices/
Regarding this product, it is so "amazing" that its literature or something worse is wrong. I contacted them asking about the discrepancy:

"HI,

I have a doubt about product AC-PCA1 CONTROLLER 1, PRE-SET THERMAL TRIGGER, FOR USB FANS AND DEVICES. On the product description it says "The four temperature triggers are 84°F, 88°F, 92°F, and 96°F" but in the technical specs says the "Programming Temperatures range from 32 to 140°F".

So, I'm a bit confused, how can you set the temperature outside 84,88,92 and 96?

Thanks."

This is what they said:

"Hi Alberto,

Thank you for taking the time to reach out to us, and I apologize for the confusion. This controller does only feature the 4 temperature settings listed on the product. The technical specs tab needs to be adjusted. Thank you for bringing this to our attention; we will be amending our product listing soon.

If you have any other questions or concerns, please do not hesitate to let me know and I will be glad to assist you!

Kind regards,
Jason

AC Infinity
"Your Cooling Solutions Provider!" "

Good attention to design, not enough on specs and literature revision.
 
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