Active Cooling 5v brushless fan with Motor Speed Controller soft PWM
#1
   

The fan above is a 5v brushless 140ma fan (free standing on rubber fan mounts) capable of moving 5cfpm ; being driven by a python software PWM motor speed control driver using a PN2222 transistor to handle the current. The GPIO pin signals the transistor via 1k ohm resistor. The codes rely on the RPi.GPIO-PineA64 module from github.

I will be uploading the python codes near the bottom of this post.

The following two pics are close-in shots of the fan, and the transistor current driver:

   

   

The PN2222 transistor above can also be replaced by the 2N2222; although, the emitter collector pins are swapped-- the emitter goes to ground.

The fans ship from Jin LI , and as such take three to six weeks to ship to the U.S. Its the shipping, not Jin LI's fault. These little fans move a lot of air; however, they are also noisy. The speed control circuit quiets the fans considerably to a slight whisper, still moves the air more efficiently, and may be controlled off, or controlled by signal based on SoC temperature.

fan_motor.sh
Code:
#!/usr/bin/python
#
# fan_motor.sh
#*****************************************************************
#  author:     Mark H. Harris        
# license:     GPLv3
#
#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
#   CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
#   INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
#   MECHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
#   DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
#   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
#   SPECIAL, EXEMPLARY, OR CONSEQUENCIAL DAMAGES (INCLUDING, BUT
#   NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
#   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERUPTION)
#   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
#   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
#   OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE
#   EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
#*****************************************************************
## Import the necessary header modules
from time import sleep
import signal as SIGNAL
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)

## SOFTWARE PWM GPIO23 pin(16)
soft_pwm = 23
GPIO.setup(soft_pwm, GPIO.OUT)

ms_on = .016
ms_off = .004
hup_flag = False

## FUNCTION DEFINITIONS

def motor_duty_on(m_pin, t_delay):
    GPIO.output(m_pin, True)
    sleep(t_delay)
    
def motor_duty_off(m_pin, t_delay):
    GPIO.output(m_pin, False)
    sleep(t_delay)

def end():
    GPIO.cleanup()
    quit()

def ssighup(signum, frame):
    global hup_flag
    global ms_on
    global ms_off
    if (hup_flag):
        ms_on = .016
        hup_flag=False
    else:
        ms_on = .250
        hup_flag=True
    print(" ")
    print("HUP: duty_cycle toggled value: "+str(ms_on))

SIGNAL.signal(SIGNAL.SIGHUP, ssighup)

kb_interrupt = False

while(not kb_interrupt):
    try:
        motor_duty_on(soft_pwm, ms_on)
        motor_duty_off(soft_pwm, ms_off)
    except KeyboardInterrupt:
        kb_interrupt = True
        print(" ")
        print("motor controller ended by interrupt, bye!")

end()

The code may be signaled with a -SIGHUP which when received by the speed controller code will toggle the duty cycle of the soft PWM. from 80% to 100%. A second HUP will toggle the duty cycle back to 80%, or slow speed.

There will be a follow-on post with some more pics, as well a simple schematic.

edit: I changed the default soft-pwm pin to GPIO23, pin(16).


marcushh777
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Messages In This Thread
Active Cooling 5v brushless fan with Motor Speed Controller soft PWM - by MarkHaysHarris777 - 07-25-2016, 06:47 AM

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