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+---- Thread: Fan Question (/showthread.php?tid=1803)
Fan Question - Bluphire - 07-20-2016
I tried searching before posting but search word must be at least 4 letters and "fan" is it 3. So please excuse me if this has been asked before. Thank you.
My question regarding the fan is, is there a way to have the fan come on only when the OS (Remix in my case) is running? For example, my fan will stay running as long as the pine is plugged into the wall, even with the OS shutdown. I do not want that.
Matt
RE: Fan Question - MarkHaysHarris777 - 07-20-2016
You can build a fan motor speed controller using a ULN2803 driver, and either software or hardware PWM.
... basically, you build a motor controller that comes on only when the temperatures on the SoC require it... and then only at a speed appropriate for the situation. I leave my fan running all the time, but running very slowly ( a hushed whisper really ). When the SoC is loaded and the temps come up... then the fan steps up ( I have two speed levels at the moment ) until the temps come down. The ULN2803 is a very inexpensive eight channel driver circuit. (I'm driving two fans with one chip). The ULN2803 is the driver on the Gertboard, if you have one of those, or want to experiment with it in a controlled way.
You may use any motor controller you choose, of course.
Keep in mind that a brushless fan can run for years with no ill affects... just let it run... if the noise bothers you then a simple pwm speed reduction circuit is all you need. Then, if you want to add some smarts to it all, make the fan run only when the temps are high.!
marcushh777
RE: Fan Question - Bluphire - 07-21-2016
I'm very illiterate when it comes to everything you just said :/ what is SoC? Any tutorials available with links to parts?
Sorry,
Matt
RE: Fan Question - Boring - 07-21-2016
Can't you just place a potmeter in front of the fan and use it to manually control fan speed. Or will it just draw more current?
RE: Fan Question - MarkHaysHarris777 - 07-21-2016
@ Boring, no, it DOES NOT WORK to control a motor speed (particularly brushless motors) with a potentiometer in-line with the motor. Motor speed is controlled with pulse width modulation (a duty cycle where the 5v is on 30% and off 70% will slow the motor to %30)... and still have 5v running to the motor... no energy is lost to heat.
@Bluphire, please read through this entire blog on the Raspberry PI site. It contains my journal (with pics) for cooling my Raspberry PI 3B units in the Black Ice Zebra Case... I'm using the Gertboard's ULN2803 as the motor driver, and the PWM of the PI to control the speed duty cycle. Of course this same technique will work with any SoC (system on a chip) and any SBC (single board computer), including but not limited to the PineA64, the Raspberry PI, the Arduino, the pyboard, &c.
marcushh777
RE: Fan Question - Bluphire - 07-22-2016
(07-21-2016, 10:28 PM)MarkHaysHarris777 Wrote: @ Boring, no, it DOES NOT WORK to control a motor speed (particularly brushless motors) with a potentiometer in-line with the motor. Motor speed is controlled with pulse width modulation (a duty cycle where the 5v is on 30% and off 70% will slow the motor to %30)... and still have 5v running to the motor... no energy is lost to heat.
@Bluphire, please read through this entire blog on the Raspberry PI site. It contains my journal (with pics) for cooling my Raspberry PI 3B units in the Black Ice Zebra Case... I'm using the Gertboard's ULN2803 as the motor driver, and the PWM of the PI to control the speed duty cycle. Of course this same technique will work with any SoC (system on a chip) and any SBC (single board computer), including but not limited to the PineA64, the Raspberry PI, the Arduino, the pyboard, &c.
marcushh777
Thank you, I will check it out and bug you via IM when I undoubtedly have questions.
Matt
ETA: Nevermind, I guess I will not be doing what I wanted to do. That process looks far too advanced for me to do. Thank you for your help anyways.
Matt