Overheating Mecool M8s Pro L and Pro + (and others ?) - Options ???

[P.X]

Where did you get your resistor??

UK in Maplin (closing down )
USA ? Radio Shack
https://www.radioshack.com/products/...-resistor-pk-5
plus other values

On The bay 1/4W Carbon Film Resistor
1Watt would better if lower resistance fan determined.

Local hobby store if still exists ???

Can you measure the current through your fan from USB ?

Rfan = V/I = 5/I

Series resistor value of half Rfan for 3.3V

Check fan runs at 3.3V by testing from UART pads. Some fans don't like too low voltage.

1/3 Rfan gives 75% Voltage

[clarkss12]

You can buy it on Amazon.

thanks, was wondering if there was any place local. Radio Shack has gone out of business.....

[clarkss12]

Voltage for fan = 4.99 current = 0.16 amp.



Tester used.........

https://www.****.com/itm/KEWEISI-3V-...-/112220806777

Same device is cheaper on Aliexpress, don't recall where I purchased mine.

[clarkss12]

I need to change the fan direction when I mount it, will switching the polarity change the fan direction without any issues?? I am making the assumption that I have a brushless motor.

[P.X]

DC fans only go one way. Need correct polarity to run ( from my experience).

31Ohm Fan

So 1W resistor best

~15 Ohm for 3.3V
10 Ohm for 3.75V
~8 Ohm for 4.0V

HTH

Check my rough calcs. ??

R = Vin.Rfan/Vout - Rfan

your Rfan = 31
Vin = 5
Vout = Desired Fan Voltage (0.00-5)


Check my transposition from
Vout = (Vin.Rfan) / (R + Rfan)

http://www.ohmslawcalculator.com/voltage-divider-calculator

[clarkss12]

I have the fan installed in the "lid" (had to use caulk ). Sitting on my desk and and fan running as caulk dries. Yes, IT IS NOISY. Guess I will order a resistor.

[P.X]

Well done
Need Photos .....
: popcorn:

[clarkss12]

Well done
Need Photos .....
: popcorn:

Crappy video posted......... What a job......... going to order resistor now.

[P.X]

Crappy video posted......... What a job......... going to order resistor now.

https://www.youtube.com/watch?v=OXx5Ri3TIwk

Viewer number 7.
Very good.
Blame P.X

That is the way I fitted my other fan in - fan pushed up from inside - and dragging air in is good (in my opinion.)

That is a hefty soldering iron, well done.

[clarkss12]

https://www.youtube.com/watch?v=OXx5Ri3TIwk

Viewer number 7.
Very good.
Blame P.X

That is the way I fitted my other fan in - fan pushed up from inside - and dragging air in is good (in my opinion.)

That is a hefty soldering iron, well done.

Thank you, what surprises me, my fan was almost silent while sitting ON my box, now it is LOUD........ Perhaps, since it is sitting pretty much on the heat sink, maybe it is obstructing the air flow causing the audible sound.

[P.X]

OFF Topic.
For your next / My latest - project (not a TV Box mod)

50" TV Stand with cantilever arm. 46" TV - Tested OK with 55" 22Kg

[P.X]

Thank you, what surprises me, my fan was almost silent while sitting ON my box, now it is LOUD........ Perhaps, since it is sitting pretty much on the heat sink, maybe it is obstructing the air flow causing the audible sound.

Yes, a bit noisier, but you can hear it at the start of the video when testing. I think the box is probably acting as an echo chamber and amplifying the sound. Also air flow is greater now it is going directly into the box ?? Difficult to guess exact cause, but a resistor will slow things down and help with the noise.

[clarkss12]

I just ordered this 1N4001 Diode - 10 pack PRODUCT ID: 755 $1.50. Somewhere on Freaktab, someone said they used a diode instead of a resistor, but can't remember who it was. Anyway, I was looking for a solution to control the fan based on temp, using a thermistor, but no luck so far. I did read where others used a diode to drop the voltage .7 volts, but does not decrease the current like a resistor. So, now I have both, resistors and diodes coming.

[P.X]

I just ordered this 1N4001 Diode - 10 pack PRODUCT ID: 755 $1.50. Somewhere on Freaktab, someone said they used a diode instead of a resistor, but can't remember who it was. Anyway, I was looking for a solution to control the fan based on temp, using a thermistor, but no luck so far. I did read where others used a diode to drop the voltage .7 volts, but does not decrease the current like a resistor. So, now I have both, resistors and diodes coming.

Both will decrease the current otherwise the fan would spin at the same rate.

A standard diode is quoted as having a forward bias voltage drop of 0.7V but it is slightly more complex than that. The voltage drop curve has a knee at 0.7V and you will probably see about that drop at the fan.
The other poster ended up using 2 diodes in series and is very happy with the results.

It may be easier to use diodes as the results will be fairly similar pretty independent of the particular fan resistance.
With a resistor in use you have to choose based on the desired voltage and fan resistance. You may be able to get a more exact speed with the resistor as you can choose smaller steps, but as found in actual use, one or two diodes in series may produce the desired result.

Let us know what you find ....

[jebivetar]

Hi

I don't have one of these yet - I just ordered an L - but I did also grab some KSD9700 thermal switches with the idea of having it close the circuit with a fan somewhere 40-50c. Someone earlier in the thread wanted to know how to turn the fan off when he goes to sleep.

I have a pretty quiet off-brand Chinese 40mm 12v that I scavenged off of some ancient device, can't remember which, that will probably be used, although I'm looking at some Sunon MagLevs if I can find a proper specced one. Note not all MagLevs are the same and the dBa ratings can vary wildly model to model, even of same dimensions.

I'll probably be running the 40mm fan from USB 5V to the KSD9700 via XL6009 buck boost module at some near-silent voltage. It barely turns on at 5v.

There are probably more appropriate tiny boost modules around, I just happen to have a bunch of these. Likewise, if you don't want to mess around with diodes and ohms gives you headaches, there are also tiny MP1584 adjustable buck converters (for stepping down 5v to arbitrary lower voltages) available for like $3 for 5.

Maybe in the future I'll look into increasing voltage as the temperatures demand.

I highly doubt I'll be keeping the M8S in its enclosure - it's exceptionally ugly, the cooling issues notwithstanding - and will probably just put it on a bunch of nylon stand-offs or something.

The parts above are a buck or two a pop and googleable.