Lolin motor schield v2

[jack100]

Hi,

Making an adjustable speed fan set for my Jaga convector with an dallas sensor. Above 25.8 degrees the fan set will start.
I connected an Wemos D1 mini at the Lolin motorshield v2.
https://espeasy.readthedocs.io/en/lates ... hield.html
Use the next fans:
https://www.freezinghardware.nl/product ... 25-mm.html
This fans are very silent.
At full speed I hear no high sound at the fans.
When I reduce at speed on the motorshield, the fan will be noisy at high frequent. A capacitor between the zero and the out signal will not resolve the problem.
What can I do too filter the high frequentie disturbe from the motor control.
The fan is not an pwm fan. It have a 3 wiring cable.
Ground, + and speed signal.
I tested the fans with my adjustable power source from 6v to 12v dc. Then I hear no high frequentie sounds.

Jack

[Ath]

From that supplier page I can not see a reference that these fans allow for speed control using a variable voltage.
They seem to require a fixed voltage (12 V) and run at fixed speed (1000 rpm), so that may explain why some whining occurs at a lower voltage/speed.

I tested the fans with my adjustable power source from 6v to 12v dc. Then I hear no high frequentie sounds.

Ah, well, then the motor board does use PWM to control the speed...

This board/motor combination doesn't seem like a perfect match.

[jack100]

Yes, Lolin motorshield use PWM.
When I lower the voltage, the fan speeds lower but becomes noisy.
LolinMotorShieldCMD,0,Forward,60
The voltage drop to 8v

Is this an better solution:
https://www.megekko.nl/product/0/173575 ... Y8QAvD_BwE

[Ath]

What capacity capacitor did you use to smoothen the output?

[jack100]

100 nF

[TD-er]

I think that controlling those fans with a PWM signal will shorten the lifetime of them significantly.

Typically those brushles fans have some very basic control circuit which will switch current on to the next coil, which is controlled by a Hall effect sensor (magnetic triggered silicon switch) to keep this in sync with the actual rotational speed of the fan.
This way the fan motor does not have to have contacts touching some coil, less mechanical wear and much less issues when the fan gets dirty and doesn't run as smooth anymore.

When you power those using a PWM signal, you may cause a much less fluent motion of the fan which will wear out the bearings. It may also damage the very basic electronics inside the fan as the coils may generate high voltages.

Lowering the voltage to control fan speed is also not a good idea as it will cause the fan to fail starting to spin when it gets older and/or a bit more dirty. Then the coils inside will likely burn out as they are not designed to have a continuous current flowing through them.

Depending on how the fan electronics are wired, you could add some delay circuit to the PWM output pin.
On some fans, this may lower the fan speed, but only when the output is directly connected to the Hall effect sensor.
If there is a transistor inbetween to make the PWM output signal more 'clean', then this will probably not work.

Another approach is to match the PWM-like steering with the actual tacho pin signal so you are in sync with the actual orientation of the fan when activating the next coil. When your PWM pulses are out of sync, you will pull the fan in reverse quickly when it isn't in sync.

Back in the days, Zalman did have fan control circuits which did start with outputting 12V to let the fan ramp up and then lower the fan speed by lowering the voltage to a set value by a potentiometer.

[TD-er]

Just found this page which does show very well how such a brushless fan motor is typically working: https://www.pcbheaven.com/wikipages/How ... tors_Work/

[ThomasB]

I suggest you try filtering the PWM so that it is an analog voltage. For example:

PWM filter

Fan_Filter.png (15.57 KiB) Viewed 1931 times

D1 is any 1A silicon diode, such as 1N4000 series,
R1 is 10 - 22 ohms, 1/2W or higher,
C1 is a large value electrolytic, such as 1000uF. 16VDC or higher rated.

- Thomas

[bidrohini]

Hi,

Making an adjustable speed fan set for my Jaga convector with an dallas sensor. Above 25.8 degrees the fan set will start.
I connected an Wemos D1 mini at the Lolin motorshield v2.
https://espeasy.readthedocs.io/en/lates ... hield.html
Use the next fans:
https://www.freezinghardware.nl/product ... 25-mm.html
This fans are very silent.
At full speed I hear no high sound at the fans.
When I reduce at speed on the motorshield, the fan will be noisy at high frequent. A capacitor between the zero and the out signal will not resolve the problem.
What can I do too filter the high frequentie disturbe from the motor control.
The fan is not an pwm fan. It have a 3 wiring cable.
Ground, + and speed signal.
I tested the fans with my adjustable power source from 6v to 12v dc. Then I hear no high frequentie sounds.

Jack

You can place an LC filter between the motorshield output and the fan's power input. The LC filter smooths the PWM signal into a more stable DC voltage, reducing high-frequency noise.
Choose values for the inductor and capacitor based on the desired cutoff frequency. Instead of using the PWM for speed control, use a linear voltage regulator like an LM317 ( https://www.pcbway.com/project/sharepro ... b30ee.html ) or a DC-DC buck converter to provide an adjustable DC voltage to the fan. ( https://www.ti.com/lit/ds/symlink/lm2596.pdf )
You can also place a large capacitor (e.g., 470 µF or 1000 µF) across the fan's power supply terminals to smooth out any voltage ripples caused by the PWM.

[jack100]

Hi all,

A new attempt.
I bought this PWM fans.
https://www.freezinghardware.nl/product ... 25-mm.html
I connected this fan to my Lolin motor shield. The 4 pins on the fan are: Ground, +, Tach and PWM.
Ground to zero 12V power source, + to 12V power source, Tach to Lolin Motor Shield, PWM to Lolin Motor Schield.

At de commands:
WemosMotorShieldCMD,0,Forward,99
12V output Lolin Moter Shield
Full speed fan

WemosMotorShieldCMD,0,Forward,50
6V output Lolin Moter Shield
Half speed fan

WemosMotorShieldCMD,0,Forward,0
0V output Lolin Moter Shield
Low speed fan (fan will not stop)

WemosMotorShieldCMD,0,Forward,0,Stop
0V output Lolin Moter Shield
Low speed fan (fan will not stop)

I changed the connection with this circuit.
http://www.pavouk.org/hw/fan/en_fan4wire.html

But the results are the same.
The fan will not stop at the command: WemosMotorShieldCMD,0,Forward,0,Stop

Please, help me
(The sound problems are solved with this PWM fans, no noisy).

Jack

[Ath]

WemosMotorShieldCMD,0,Forward,0,Stop
0V output Lolin Moter Shield
Low speed fan (fan will not stop)

Does the fan stop when, once it's running, you disconnect the PWM signal?
Does the fan start running when *only* GND and +12V are connected?

[jack100]

No (Does the fan stop when, once it's running, you disconnect the PWM signal?)
Yes (Does the fan start running when *only* GND and +12V are connected?)

[Ath]

No (Does the fan stop when, once it's running, you disconnect the PWM signal?)
Yes (Does the fan start running when *only* GND and +12V are connected?)

In that case I don't think you can make this fan-type stop running when controlled via the motor shield

To find a fan that does stop when not sending a PWM signal obviously takes some effort. Not all fans are capable of doing that.
Not sure if that info is available in the specs.

[TD-er]

Or you also let the 12V run via a FET so you can completely start/stop it.

[jack100]

Hi,

I try another type fan.
Be quiet. The Silent Wings 4, 140mm PWM.
Expensive but very quiet (13.6 dB(A)
Lifetime 300.000 (bearings in fluid)

At the command:
WemosMotorShieldCMD,0,Forward,0
0V output Lolin Motor Shield
This fan will stop!

Jack

[jack100]

Or you also let the 12V run via a FET so you can completely start/stop it.

I try this.
But the fan (Gelid pwm fan) will not stop with the MOSFET at 12V.

[Ath]

This fan will stop!

Great, problem solved