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Topic: How to run 4 coreless dc motors in Arduino using proper MOSFET  (Read 1 time) previous topic - next topic

Uddipta_64

Hi! I am trying to make a micro drone of about 12 cm with Arduino Uno with 4 high power coreless dc motors of 3.7volts



from here ----



(https://www.amazon.in/JJ-Coreless-Propeller-High-Speed-AK0DRONEA/dp/B07F2HV34K/ref=pd_sbs_328_1/260-5041674-6275528?_encoding=UTF8&pd_rd_i=B07F2HV34K&pd_rd_r=97e84305-a601-11e9-8e05-f11eafe56b55&pd_rd_w=g7YEc&pd_rd_wg=MMJXV&pf_rd_p=87667aae-831c-4952-ab47-0ae2a4d747da&pf_rd_r=M76WWNT117WKNK7X4Q38&psc=1&refRID=M76WWNT117WKNK7X4Q38)





 which needs a current of  800ma.I was trying to make that without using any MOSFET.
But after running I saw that it was generating a really low thrust .After some research in Google i found that the pwm pins can only give out a current of 45mA which is really not sufficient for my motors .I found that MOSFET is really necessary for running the dc motors at their highest rpm. Now my question is that what
MOSFET required(specification of the MOSFET transistor) to run them at their highest rpm? and also ,is 3.7volts lipo battery enough to fly my drone with arduino uno? Are the coreless motors enough powerfull for lifting the drone?

I would also ask another question . what mus be the propeller size for 12cm drone.

Thank you in advance..

jremington

Please post links properly, after removing your personal tracking ID, like this:
https://www.amazon.in/JJ-Coreless-Propeller-High-Speed-AK0DRONEA/dp/B07F2HV34K

You should never try to draw more than 20 mA from an Arduino output pin.

General circuit for using a logic level MOSFET to control a brushed DC motor.


Uddipta_64

Well thank you very much :) .

But after some research I found that for using MOSFET  with coreless motors they must not be connected to the arduino pins.An external power  for example lipo batteries are to be connected with the motor.Then how do the 4 coreless motors of a drone are powered at highest rpm with a single lipo battery.

Can you please send me the circuit or just explain how to power 4 coreless motors at their highest rpm with a single lipo battery :( ?

jremington

Just about everyone uses a circuit like that posted in reply #1, repeated four times for four motors.

Uddipta_64


slipstick

But how to run all of them with a single lipo battery
What's the problem? The battery connects to Vsupply and Ground of all four MOSFET circuits and so connects to all four motors. The gate connections marked DIG OUT go to four separate Arduino pins.

Steve

Uddipta_64

 :) Thank you I understood. But the basic problem is that I need to use logic level MOSFET which is available in our town but the shopkeepers don't give without numbers.So can you suggest the number of my MOSFET.

jremington

Any logic level MOSFET that can easily handle the stall current of your motors will work.

Find out what that stall current is.

Uddipta_64


jremington

Did you forget to check whether the IRF540N is a logic level MOSFET?

Uddipta_64

After googling about irf540n I found that these can support 23A and a peak current of 110A which is really sufficient for my 4 coreless motors each of 800mA . It also said that it has threshold voltage of 4v which can easily run a 5v arduino.It also said if I am running high current devices with logic level then irf540n MOSFET is perfect.

jremington

The IRF540N won't work at all. The threshold voltage is irrelevant. If you look carefully at the data sheet, you will see that the currents are specified with Vgs = 10V (Vgs = gate to source voltage).


slipstick

I don't know what the "it" is that told you "if I am running high current devices with logic level then irf540n MOSFET is perfect" but I wouldn't take any advice from it again.

One hint that the IRF540n is far from perfect is that the specification doesn't say "Logic Level" anywhere but the really serious hint is that the threshold voltage is as high as 4V. Since that's the point at which the MOSFET just about starts to think about conducting it's really unlikely that it will be fully switched on with only 5V.

Steve

Uddipta_64

Did you mean that it can run with arduino uno. And if not then why the hell they gave it here>>>(https://components101.com/irf540n-pinout-equivalent-datasheet)

They said to connect the motor pin with drain ,I also did the same . Though I didnts test it as I don't have lipo battery at this moment. I have ordered 2800mah from amazon.

slipstick

How can I tell why some website says things that are wrong?

There are many better MOSFETs to use with Arduinos, even the old IRL540 which is a genuine logic level device. But for a small drone I'd want to use much smaller lighter MOSFETs and there are plenty of those too.

Steve

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