Oh thats a nice idea, but i am wondering whats the advantage compared to using 2 resistors and let it run with 3.5V? Because the SFP+ cages are always hot. Maybe thats a nice idea for the cpu fan. I am already looking to replace the original heat sink and replace it with one that does not have a cut-out. Then i could place the sensor on that and use the controller for the cpu fan. But… when i create a 3.5Vout “component” i could use both FANs and just let them run. I have resistors and a lot of such small components here now, so i could instantly start. When i order, i have to wait. What would you do?
I would try to see what is really needed inside the sfp cages and see if that what I need can be done with generating less heat.
I know that its working on full speed, but thats not what i am looking for. I would go nuts if this thing turns on and off all 5-10 minutes.
@ericwoud I’ll build the simple voltage limiter to 3.5v with 2 resistors (should not produce that much heat, shouldnt it?) and see how it works.
Why do you think that? Please clarify.
The 3 pins connector on the R4 and the included fan are non standard and have for pinout 5V (red wire) GND (black) and PWM (yellow). Your fan has a RPM signal instead of the PWM like nearly all 3 pins fans. There are two ways to use a PWM signal to control these fans (read the 2nd and following paragraphs of “Controlling Fan Speed” on page 6 of this datasheet). Another option is to buy the NF-A4x10 5V PWM and makes an adapter (I have done just that with a NF-A8 5V PWM mounted on a 3d printed plate to replace the top plate of the case).
I’ve made the adapter using this cable and a 4 pins connector (don’t forget to check required pins). To remove the 3 pins connector of the cable I’ve used the pins as the thin object in the image below.
Hello Oli,
I think you know now what the difference between a PWM and Voltage controlled fan is …
And Banana PI drop away “RPM Speed Signal” pin on the R4 board. That also brings me in some trouble my first time!
You can inform you at R3 about equal topics - for example:
→ there is were i made my first steps :see no evil:. But there are more R3 fan chats …
One of your questions was how to get 3,3 voltage?
The 26 Pin GPIO header delivers that by default:
→ hoping that a fan do’s not have to much amps for the task!
I had the same thinking like you.
- One big fan?
- Two small fans?
- How to get the temperature reading? Can I read it out and control a PWM Fan over the 26 Pin header?
→ May be
.
Yes, i knew that before my initial posting. But the schematics clearly states “PWM” and not “Voltage controlled”. @TheServer201 mentioned that the 3rd wire of the R4 is indeed pwm, but there seems to be nearly no fans that by default have this layout. I will read further today when i am back from the meeting now.
Unfortunately, it would be better to have 3.5-3.7v, i assume thats the sweet spot (not hearable and max. air flow), not sure if 3.3v would be enough. But i will test that today with gpio and 3.3v as i assume, thats the easiest to achieve compared to creating again jst connectors … i am too old for such small stuff 
One noctua requires 0.4A. And i know now what my “goal” is: one fan should be fixed at ~3.6v for the sfp ports (but will try it with 3.3v today) and the other controlled by pwm (if possible) or also at ~3.6v. Do you know whats the max. wattage is of the gpio pins? Can the 3.3v handle 0.8A?
@TheServer201 thanks i will read this in about 7h and probably ask some more questions 
Can you maybe share a picture of your R4 where your fan is located?
The pwm pin just pwm’s 3.3v at 2A, according to schematic. You can connect any load that can operate with these levels.
The mosfet is hooked up differently, so no 2A switching…
So you would need a mosfet to drive a 2 or 3 wire standard fan.
the sfp fan is now working like a charm @3.3v thanks @Lorem_amicus , but i noticed something wierd… when i lay down the fan on the sfp cage, i am somehow unable to get an ip. When i let it “float” a bit (e.g. use the antenna cable to push the fan a bit over the sfp cage) it works like a charm. Anyone an idea what could cause that?
I was planning to use some heat absorber tape to tigthen the fan to the sfp cage, but when i dont get a connection anymore… its a bit useless 
small measurements (wip):
- 43.5°C with case open and oem fan
- 41°C with case open and noctua fan (on the cpu @3.3v)
- 50°C with case closed and noctua fan (on the cpu @3.3v)
- 53°C with case closed and oem fan
- 52 °C with case closed and oem fan on the cpu and noctua @3.3v on the sfp cage
The noctua was laying on the oem fan so not a real comparison, guess @4v and on a good heat sink it would produce way better results
@TheServer201 what do you use on the cpu? do you use the same heatsink like i do or do you have something else? Can you share a bit information about the pwm-signal-adapter you built?
Not at home but I can take pictures sunday. I’m using this heatsink over the CPU and this one over the SFP+ cages. I’ve set the fan to be at the center of the top plate (see image). Since I have a PWM fan my adapter looks like the cable that I have linked in my last post and doesn’t contains anything more than wires and connectors.
Shipping is nearly 20 EUR for the CPU heat sink :X
Any idea how to get that to germany or switzerland without paying that much? Or any alternative?
Shipping is free for orders above 50 EUR (I brought along some ic for other projects). Finding a heatsink without a fan that covers the whole 50x50 square is really hard and even this one is not perfect (the distance between the holes should be 59 / sqrt(2) ~ 41.719mm whereas this have 43mm).
Had the same issue with digikey for wifi module, ESP gateway and others. They don’t like to handle small personal orders hence the high shipping cost I guess and the free shipping above 50€.
So best would be to order a slightly bigger heatsink, those special spring screws and drill the holes in the correct distance myself?
Thats what i am thinking now too
Here are the photos. The top is not yet finished the mounting holes doesn’t work with the Noctua NA-AV1, the fan wire is a bit too much bend and the uart adapter cannot be secured with double side tape yet.
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Oh thats neat. The FAN is running all the time @5V i guess, but as its a 5v noctua fan (92mm or 80mm?), it probably is not noticeable? Thanks for the picture. When my perforated top arrives, and when i am finished with the FAN setup, i will post a pic too
It is a 80mm fan and yes it run on 5V but with the PWM it is never spinning at 100%.