Does anyone have ideas for controlling a small fan in OpenHAB without using a desktop with fan headers? I have openHAB running on a laptop, with a Raspberry Pi nearby if it helps. I would like to add a small fan to the cabinet it’s in, but ideally, I would be able to control the fan with openHAB rules. With all the ceiling fan controllers and knob based small fan controllers, I’m having trouble searching for something. I think I need some kind of software controllable USB fan regulator, but I can’t find such a thing. I’m open to ideas. Thanks!
Hi @Nick_of_408,
I’m sure what you want to do is possible, but I presume you want to regulate the temperature of the cabinet. If so, it may be better to forgo trying to automate it via openHAB and instead use something that is directly temperature controlled. You could add a temperature sensor of you choice to the cabinet to monitor the temperature if desired though.
Regards,
Burzin
Thanks @Burzin_Sumariwalla Yes, I may have to go that route. That would be easier, and not dependent on OpenHAB. However, I like being able to see what’s going on with graphs, and I’m already monitoring temperature in there. I think I might have found a good option in MikroBUS.
I don’t know anything about mikroBUS yet, but I I found this voltage regulator:
It’s cheap enough though, so I’ll probably give it a shot.
I’d rather run it from my OpenHAB laptop that my Raspberry Pi, so there’s also this option that I might go with:
OMG… So many click boards. I might lose a few hours if I start looking through them. Definitely going to do that at some point though.
I’ll probably go with this one for the fan:
Did you think about using fanless embedded pc? There are couple of options - with and without storage as well as with/without IO. I did some tests with Dell Edge 3001, Aaeon Boxer 6405, up squared and had a look on rpi compute module.
Overall if you have system sized to work up to 60C and you keep cpu load at affordable level then you can run it indefinitely. One of major sources of heat is SSD drive - so if you can avoid it - you have 10C premium.
Cheers, Łukasz
@splatch That’s a good point. I might just leave it as it is. The thing is, I changed cabinets, and the heat went up a bit inside the cabinet. But it’s not really at crazy levels anyway. The CPU sits idle at 50C and under load (using stress), I’ve never seen it go above 64C. I didn’t notice any change with CPU temperatures, but there must be some when I changed cabinets. The ambient temperature in the cabinet compared to the ambient temperature outside of the cabinet went from about 6F to about 10F (you can just divide that by nine fifths, as I prefer Fahrenheit for temperatures I can feel). I guess it might not be worth throwing a fan in.
Also, I’ve noticed that the particular HDD connected to my system is much hotter than my SATA connected SSD. I always thought that was strange. It’s an old 500GB SATA drive on a USB converter vs an old 256GB Kingston SSD connected through SATA. The solid state drive is always warm, but my spindle drive is hot. A 5TB replacement for it arrives tomorrow. I also run NextCloud on this machine.
You’re right - it is a storage. Amount of power needed to spin HDD, as well as amount of heat coming from traction between elements, is much higher than SSD and SSD will need more power than onboard eMMC.
Most of temperature constrained computers rely on own storage and heat sinks which can emit it from warm elements over a case. If I remember properly I’ve seen models from Advantech in absurd procies, yet they could work up to 80C, above most of PLC systems. 
Standard equipment can work up to 60C with no issues. There are computer models with space for additional drives who permit you to have an extra m2/mPCI cards or disk at expense of limited temperature range. From my own findings - a drive takes at least 10C of available temperature space. Most of catalog cards I browsed clearly states that an SSD drive is yet another heat source.
You can check stores who sells industrial equipment. There are SSD drives marked with “wide temperature” and normal ones. I never had a look on details - but it seems that WT ones must emit a bit less heat than standard ones which allows you to close it in a cabinet and leave equipment with limited airflow.
I’m also looking for a solution to control a fan that I like to mount in our tv cabinet and control it via openhab/knx. The cabinet has quite some electronics in it, when temps rise I want to turn on the fan, or even have it turned on at a certain speed/rpm. I found a 24V PWM fan which uses PC/intel spec pwm system. I tried using a qubino rgbw led dimmer I still had, but perhaps the frequency is off? I at some point it goes to 0rpm and suddenly to max. not exactly what I had in mind. Anybody know of a better way to control such fans besides just turning it on/off