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Using Arduino => General Electronics => Topic started by: 17Nico17 on Feb 19, 2020, 11:19 am

Title: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 19, 2020, 11:19 am
Hi everybody!

Nice to meet you all. I am new on this forum (french so please forgive my possible english issues^_^). I am also new on electronic things and my domain is usually more mechanical engineering stuffs.

I have an issue, and despite lots of researches I still do not find precise answer to my questions.

The topic is quite common, command a 12v motor using :

- 12v alimentation
- MOSFET N channel IRFZ44
- Arduino Mega

To summarize, hardware side:
- Gate is linked to PWM compatible output of the Arduino (PIN11)
- Drain is linked to the motor
- Source is linked to the ground

What happens? :

-When I have 0% on PWM signal, that is to say 0 over 255 on analogWrite command, 0V for motor, this is OK
- When I have 100%, 255 over 255, motor has 12v, so this is OK too
- When I have <1%, or 1 over 255, motor has around 7V and this is the issue
- When I have 50%, so 127 over 255, motor receives around 9v.. so quite linear if we consider that starting point is the 7v above.

I have read that I should have resistances between ground and gate to pull down (10 kohms) and between the Arduino PIN and the gate (100 ohms) but nothing changes.

I have tried with :

- 2 different arduinos
- with or without resistances and with several values (10k, 100k, 1M for pull down, and 20, 100, 200 for the other one)
- 2 different MOSFETs

I have seen that tension between PWM signal at 1% and ground was 0.5v, maybe this is a clue? It seems quite high...

I have also read Vgs tension is crucial (logic TTL MOSFET existancy) mine is equal to 10v in the datasheet (seems to high for my Arduino) but finally some other topics say that this is ok because Vgs (th) is 2v mini so Ok for Arduino (and his 5v). As I reach the 12v when I am at 255, I guess that this MOSFET (IRFZ44) is compatible with Arduino PIN?

In conclusion, I am a bit lost with all of this. I really need your help to progress on this topic.  :smiley-confuse:

Really thank you for your help.  :)  I am aware that this is something that should be easy but I do not find the solution.

Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 19, 2020, 11:34 am
Hello 17nico17

Welcome to the Arduino fora.
Before you do anything else please take a moment to read General guidance (https://forum.arduino.cc/index.php?topic=652669.0")
And
How to use this forum (https://forum.arduino.cc/index.php?topic=148850.0)


You are asking us to help without seeing a schematic or code, which makes helping difficult. We get frustrated and move on to a different question, you don't get good answers.

Thank you.

PS. Your English is fine  :)
Title: Re: MOSFET N channel transistor curiosity
Post by: knut_ny on Feb 19, 2020, 11:46 am
Wrong transistor for 0V..5V PWM
U'll need a logic level transistor  (IRL..)  or additional transistor (or MOSFET driver) to allow better control over gate voltage
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 19, 2020, 12:50 pm
Hi both of you, and thank you for your replies! :)

Sorry for the presentation, I attach the code I have. It is very simple thing so I did not attached it in the first post.

I think the program is not the problem. Maybe this is not perfect but thank to the monitor I can see that the correct information are sent to the transistor.

My connections are the same as the schematic attached (copied from the internet). The only thing is for the moment I did not linked the motor. I want to understand what happens before adding the motor. I just measure the tension that the motor will receive.



Thank you Knut_ny, you confirm what I have read on some posts.  :)
I still have a question. In my mind, if MOSFET Vgs is too high, Arduino is not able to allow the transistor to be as its lowest resistance. So it would be impossible for me to reach 12v on final output, right? (maybe here is my mistake). In fact I notice that my issue is quite the contrary. I do not reach the 0-7v range. But I have the 7-12v one...

I have seen some guys advising for some logic level transistor but when I look at the datasheet I always see Vgs = 10v, Vgs (th) mini 2v and maxi 4v.... so quite the same as what I currently have.

Could you advise for a precise transistor that would work fine?  :)

Really thank you for your help, you are really my last hope on this topic!  :o



Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 19, 2020, 01:09 pm
Hi both of you, and thank you for your replies! :)

I attach the code I have.
Why have you attached an image of text? You have not read and followed the forum instructions have you? Attaching an image of your code is daft.

Your schematic has connections to something on the right hand side that cannot be seen.

As I have already said:
Quote
We get frustrated and move on to a different question, you don't get good answers.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 19, 2020, 01:24 pm
Yes, I have read the 2 documents  ;)

Oh sorry, I have used "attachement" tool. It was part of the 2nd document. As I had two pictures, I have chosen this option. Did not know it was prefered to add as text instead, sorry again.

The connection on the right hand side is just a diode for the motor (called "diode de roue libre" in french, do not know the english expression). I cut it to not overload the scheme. As for the moment the issue is present without the motor, this diode does not really matter.

Yes, I understand for the rules, this is normal. This is more clumsiness from my side, sorry.  :smiley-confuse:
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 19, 2020, 01:48 pm
Here with the good shape :

Code: [Select]
#include <Servo.h>


int Valeur_analogique_moteur = 0;

//---------------------------------------------------------------------------------
void setup() {
 

pinMode(11, OUTPUT);
pinMode(41, INPUT);
   Serial.begin(9600);
 
}

//---------------------------------------------------------------------------------


void loop() {
 
unsigned long Haut = pulseIn(41, HIGH, 1000000) ;
unsigned long Bas = pulseIn(41, LOW, 1000000) ;
                               
Valeur_analogique_moteur =  Haut*255 / (Haut + Bas);
Serial.println(Valeur_analogique_moteur);
                                     
analogWrite(11,Valeur_analogique_moteur);
 


And the picture of the circuit (hope this will work, the preview does not show it):

(https://zupimages.net/viewer.php?id=20/08/inin.jpg)
Title: Re: MOSFET N channel transistor curiosity
Post by: slipstick on Feb 19, 2020, 01:54 pm
One of very many better MOSFETs would be the IRLZ44. The L means 'logic level' and you'll see that the Rds is quoted for 5V and that is the best thing to look for.

Steve
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 19, 2020, 02:20 pm
That's better  :)

The replies from  knut_ny(!?!) and slipstick are probably what you need, I have nothing more to add.

Posting images is a pain on here. Upload the image to your post and save. Then right click on the file name of the image and select 'copy link location' (or the equivalent in your browser). Go back and edit your post. Use the 'insert an image' icon from the tool bar at the top of the edit box (roughly in the middle) and use the link you copied.
Title: Re: MOSFET N channel transistor curiosity
Post by: MarkT on Feb 19, 2020, 03:12 pm
I have seen some guys advising for some logic level transistor but when I look at the datasheet I always see Vgs = 10v, Vgs (th) mini 2v and maxi 4v.... so quite the same as what I currently have.

Which FET was this?  Sounds like they got it wrong too.

The only specifications you need to look at for a MOSFET are the polarity, max Vds and the Rds(on), you should ignore the others until/unless you know what they mean!

If and only if the datasheet has a resistance value for Rds(on) quoted at "Vgs = 4.5V" is the MOSFET logic-level.

If that 4.5 is even lower, then its also logic-level, but you'll need to check the absolute max Vgs isn't too small (+/-20V is good, +/-10V or so is borderline).

Voltage ratings should be at least double the operating voltage to allow for inductive ringing on fast switching edges.  So a minimum Vds rating of 25/30V is advised for 12V operation for instance.
Quote
Could you advise for a precise transistor that would work fine?  :)
Describe the requirements accurately then, max stall current of the motor for instance.


BTW measuring voltages of switching waveforms with a multimeter just gives the average over the waveform, doesn't tell you the actual voltages.  A 'scope is needed for this.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 19, 2020, 04:55 pm
Thank you for your help, really, I better understand now. Thank you MarkT and Slipstick!!  :)  :)

I have found IRLZ34 in a workshop in my city, the guy told me it was the closest he had for IRLZ44. I will try that today evening and tell you if it works.

PerryBebbington, sorry but I am stuck to the link stuff when the picture is on my computer  :o  I got the rest I guess anyway.

Really thank you for these precise and complete answers. I really hope that everything is going to work fine now! ;)

I'll let you know anyway!
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 19, 2020, 08:26 pm
Grrrr bad news, I have the same issue..... :'(
In the Arduino monitor my 8 bits value is 5 / 255 and the tension between the Drain and the + is around 8v....

Really do not understand why. No motor to simplify the system, only a PWM and the transistor...
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 19, 2020, 08:29 pm
Really do not understand why. No motor to simplify the system, only a PWM and the transistor...
Do you have any load on it at all? Even just a resistor, maybe 100 Ohms or something?
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 19, 2020, 10:40 pm
Can't believe it, it works fine with a 3300kohm resistance!!! I did not know it could change the result! Thank you PerryBebbington!

As I am here, maybe you could advise me a diode for the motors?  :smiley-lol:  I will have 2 motors in parallel. These motors are 12v ones, around 2A in total maximum (they are almost turning without resistancy). They are brushed style 775 type.

What a pleasure to see the tension from 0v to 12v following the % indicated by the PWM generator!  8)  8)
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 19, 2020, 10:49 pm
You've not provided a schematic but from your description I suspected you had an open drain you were expecting to have a changing voltage on. With no load there was nothing to provide a complete circuit, so the voltage you were getting was whatever stray voltage you happened to pick up.

Do you understand  Ohm's Law (https://en.wikipedia.org/wiki/Ohm's_law) and Kirchhoff's circuit laws (https://en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws)? They are key to your problem.

Quote
As I am here, maybe you could advise me a diode for the motors?  :smiley-lol:  I will have 2 motors in parallel. These motors are 12v ones, around 2A in total maximum (they are almost turning without resistancy). They are brushed style 775 type.
You need to know the stall current (current with the output shaft locked so it can't turn). The diode must be able to carry at least the stall current +, maybe, 50%.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 07:43 am
Thanks for your help PerryBebbington! Ohm's law yes ;) Kirchoff's law too, but not studying that for 10 years  :smiley-roll:
All I remmember is that tensions are the same potential at the same nodes and in the different "loops" and that we have current additions at these same nodes.

Regarding my motors, stall current is 20A per motor.

I try again for the circuit picture (this time with the link from my PC). Picture is also attached in case :

(http://file:///C:/Users/NICOLAS/Desktop/Schema_diodes.jpg)

Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 09:11 am
(https://forum.arduino.cc/index.php?action=dlattach;topic=665614.0;attach=347559)

The usual convention is positive at the top, negative at the bottom of the schematic, the opposite to what you have.

Quote
Regarding my motors, stall current is 20A per motor.
Then the diodes need to be rated for at least 25A. I don't have a specific diode in mind, time for you to do some research, unless someone here can suggest one.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 10:15 am
Ok, I have so many things to learn  :o
I have found some diods, do not know if it should to the job...?

1st : DIOTEC SEMICONDUCTOR P2500K
2nd : MBRB2545CT (seems to be two diods inside?

I guess that I do not have the good key words in Google to find what I need because I do not know much about this domain unfortunately... If some guys know about diodes, I take  :D

Thank you again (+ for the picture)!
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 10:26 am
Something I didn't pick up on in my previous post:
You have 2 motors in parallel that between them might draw 40A. Is the power supply and the device switching the power capable of supplying 40A?

Also, now I am thinking about it, I am not sure about using 2 diodes that will be in parallel as the motors are in parallel. I can see a risk that one diode will end up carrying the kick back from both motors, which is potentially 40A. I think one 50A capable diode is needed, not two 25A diodes.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 10:48 am
One point for you PerryBebbington! My general switch is 20A...  :smiley-confuse:

Ok, for the diode, I also thougth about something similar for the parallel/serie stuff. As I do not know how it has to be cabled in the case of 2 motors in parallel, I supposed it was a good idea two have 2 diodes.

My motors will turn freely in a normal use. The only duty they have is to send a ball that will be sent by friction with 2 wheels. Using a instrumented alimentation, current is lower than 1A even when the ball is launched (max normal current).

It could be a good idea to add a fusible (20A) before the motors maybe? A fusible that can be reingaged (I have some like that, they do a "click" when above the indicated current and you can re-engage them). The only way the current is 40A is if a ball is stuck or something like that.

Edit : I forgot to say that my alimentation will be a LI-PO battery, 3S 5000 mAh 20C (11.1V).
So I search for a 50A diode now?  :smiley-lol:   Do you have an idea of the scheme with only one diode?

Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 11:19 am
Quote
My general switch is 20A...
It's not going to last long... Maybe you need one for each motor.

Quote
My motors will turn freely in a normal use. The only duty they have is to send a ball that will be sent by friction with 2 wheels. Using a instrumented alimentation, current is lower than 1A even when the ball is launched (max normal current).
When the motor is stationary and you apply power it will draw its stall current, even if only for a fraction of a second. This probably won't show on a multimeter. You have to account for this. Also, you cannot ever guarantee that 'normal use' will always apply.

If you put the motors in parallel and the diode across each motor then the diodes are in parallel. The electricity won't care which diode is where, it'll just follow the rules of Ohm's law. If that means more current in one diode than the other and the diode is overloaded then it goes pop, quickly followed by the other diode and the driver. I think probably you should have separate drivers for each motor and a diode for each motor. If the motors have a 20A stall current then I suggest drivers rated for at least 25A and diodes the same.

Quote
It could be a good idea to add a fusible (20A) before the motors maybe? A fusible that can be reingaged
It won't protect your diodes or drivers. Silicon blows a lot faster than any fuse. Fuses are mainly for protecting against fires caused by overloaded cables. The battery you suggest is easily capable of starting a fire if shorted out; you should use fuses for that reason, but don't expect them to protect your silicon devices, they won't.

Quote
alimentation
That's a new word to me, what does it mean?

Quote
So I search for a 50A diode now? Do you have an idea of the scheme with only one diode?
The more I think about it the more I think you need 1 driver and 1 diode per motor, not 1 driver and 1 diode shared between them.

If there is someone reading this with a different perspective please will you comment and help?


 

Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 12:30 pm
Quote
It won't protect your diodes or drivers. Silicon blows a lot faster than any fuse. Fuses are mainly for protecting against fires caused by overloaded cables. The battery you suggest is easily capable of starting a fire if shorted out; you should use fuses for that reason, but don't expect them to protect your silicon devices, they won't.
What I meant is to have a general fusible to protect the main switch. The idea is to keep the diodes above (stronger) to be sure I will not have any issue with them. Regarding the motor size, I am quite sure the fusible will not pop in 99.9% of the situations. If it pops, it is acceptable for me to re-engage it and maybe better to have it rather than having a strong global circuit for quite nothing finally.

Alimentation is a french word. I thought it was transparent. This means feeder (electric feeder, power supply is maybe better).

For the diode, I do not hide that it would be easier for me to control everything only with one transistior and one diode as I do not have much space and I want to keep the whole package as light as possible. If I have to, I will do. But if a solution exists with only one diode, I'll take it. ;)
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 12:39 pm
Quote
For the diode, I do not hide that it would be easier for me to control everything only with one transistor and one diode
Then the transistor and the diode need to be able to comfortably handle the total stall current of both motors, plus a margin of maybe 20% - 25%.

Something I've not pointed put is that you can't put 2 diodes in parallel and expect them to
carry twice the current of 1 diode. Diodes conduct when the applied voltage reaches their Vf. This will vary between different diodes due to manufacturing differences and temperature. Whichever diode has the lowest Vf will carry most or all the current, the other one will get very little. The one carrying the current will warm up, lowering its Vf and thus making sure it gets still more of he current, until it dies.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 01:03 pm
Quote
Something I've not pointed put is that you can't put 2 diodes in parallel and expect them to
carry twice the current of 1 diode. Diodes conduct when the applied voltage reaches their Vf. This will vary between different diodes due to manufacturing differences and temperature. Whichever diode has the lowest Vf will carry most or all the current, the other one will get very little. The one carrying the current will warm up, lowering its Vf and thus making sure it gets still more of he current, until it dies.
Ok, I understand, it is worse and worse. We call it "Vicious circle" in french.

Ok, so if I find a 40A diode I put between general positive of my 2 motors and drain of the transistor I am ok normally if I take a 15A fusible to protect the whole system? I have 30% margin for my diode and a comparable margin for my switch.

I can begin like that and see in the future. If I have to re-activate the fusible too often, I will make an upgrade then ;)

What do you think about this plan? Just need to find a 40A diode, will be huge no?...  :o 
I just see that I must have a 60A mini because of the fact the fusible would probably take more time to pop even if it is less strong than the diods on the paper.....

Something like that is ok?

[url/]https://fr.rs-online.com/web/p/diodes-de-redressement-et-schottky/7003734/[/url]
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 01:20 pm
I think that's reasonable to try.

Do your motors really take 20A stalled? Have you measured it?
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 01:29 pm
It is mentionned on the datasheet the 20A. I did not measured it. What I measured is that my consuption during normal use was around 10W for 2 motors together (motors are not always at 12v).

I have found this kind of diode too. There are so many types i am lost to be honest....  :o

https://www.conrad.fr/p/diode-tvs-littelfuse-15ke39ca-do-201-371-v-15-kw-140802 (https://www.conrad.fr/p/diode-tvs-littelfuse-15ke39ca-do-201-371-v-15-kw-140802)
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 01:31 pm
Quote
It is mentioned on the datasheet the 20A. I did not measured it. What I measured is that my consumption during normal use was around 10W for 2 motors together (motors are not always at 12v).
It seems too high to me. I suggest you measure it. You might be trying to solve a problem that doesn't exist.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 01:37 pm
Ok, sound quite high to me too. Arff I do not personnaly have the tools, I will have to ask a friend. Anyway, maybe this is a good idea to have a strong diode?

Did you see my links? There are many types, cylindrical, square, with different names & prices, I really do not know what is good or wrong.  :smiley-confuse:
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 02:29 pm
Find out what the real stall current is then look again.

I looked at some of them, but as I suspect the current we are looking for is too high I think you should wait until you know what you really need.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 03:19 pm
Ok, I should have this info tomorrow.

What did you find anyway? Mine are not suitable I guess  :smiley-yell:  (they were 60A mini)?
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 03:31 pm
I didn't come to a conclusion, I was waiting for you to find out more.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 04:25 pm
Ok, I come tomorrow with these information ;)
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 20, 2020, 05:08 pm
Sorry, something I forgot, probably because I don't play with motors much. I was reminded reading another discussion. Measure the resistance across the motor. Turn the motor slowly by hand and look for the lowest reading. Divide the supply voltage by the lowest reading to get the stall current.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 20, 2020, 06:12 pm
Off course, you are right, this is obvious now you talk about it! ;)
I measure 1.8 ohm minimal value. It is around 2.0-2.2 most of the time and 1.9 et 1.8 in a precise position for both motors. :)

I deduce that stall current is 6.15A (I will have 11.1v). This is in the case my motors are turning 100% speed and are blocked. In reality I will only use 7-8v maxi (wheels will be too fast after). So in practice if I have 4.5A per motor it would be the maximum. ;)

I guess that it is good news!!

Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 21, 2020, 02:03 pm
It sounds a lot more reasonable!

Quote
In reality I will only use 7-8v
How are you varying the voltage?
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 22, 2020, 02:29 pm
I make the tension varie using the Arduino. In practice, according to the first tests I have done, 11.1v will be too much and will make the balls to quick. I can consider in a very very extrem case having 11.1/1.8 = 6A but I guess that I will never have that.

A 15A diode should be sufficient then. Or 20A if we need more security.

Remains to find one...  :)
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 22, 2020, 02:39 pm
Quote
I make the tension varie using the Arduino. In practice, according to the first tests I have done, 11.1v will be too much and will make the balls to quick. I can consider in a very very extrem case having 11.1/1.8 = 6A but I guess that I will never have that.
If you mean you use PWM to vary the voltage then that's what I was afraid you were going to say. PWM does not vary the voltage, it varies the time the voltage is applied for; the full voltage is still applied to the load. If you meant something else then please explain because I can't think of anything else you might mean.

Quote
A 15A diode should be sufficient then. Or 20A if we need more security.
No harm in higher, possible harm in too low.

Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 24, 2020, 10:01 am
Hi PerryBebbington! Hope you had a great WE ;)

Yes, I see what you mean, the medium voltage is lower but I will still have +12v some time to time depending on PWM signal. So I have to take into account the maximal intensity!

About that, I have some news and they seem to confirm the 20A I had in the datasheet. Under 1.2v voltage, I have 2.5A following the power supplier of my friend. We tried at 3v but it was higher than 6A and his power supply maxi current is 6A so it was overwelmed by the demand.

I would give around 25A for the stall current even if I measured only 1.8 ohm minimal value for both motor....

So, I definitely need a 50A diode...
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 24, 2020, 10:42 am
Quote
Hope you had a great WE
Thanks  :) You too!


Quote
Yes, I see what you mean, the medium voltage is lower but I will still have +12v some time to time depending on PWM signal. So I have to take into account the maximal intensity!
Correct.

Quote
So, I definitely need a 50A diode...
OK, do that. I can't help thinking it's higher than needed, but better higher than not high enough.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 24, 2020, 11:00 am
Thanks! :) Yes, I agree. I have found this one. Is this kind suitable?

https://www.mouser.com.gt/datasheet/2/427/vs-80cpq150-48561.pdf (https://www.mouser.com.gt/datasheet/2/427/vs-80cpq150-48561.pdf)

I see that this has 2 diodes inside? 2x 40A? Do you think this can be ok? And how do I have to connect it? Can I use the two diodes together?

I try to find the same with only 2 legs for 50A or 60A but no success....

I also have this kind, but seems strange that this little thing takes 100A??

https://www.mouser.fr/datasheet/2/240/Littelfuse_TVS_Diode_P6KE_Datasheet.pdf-741008.pdf

Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 24, 2020, 11:08 am
That'll be OK.

Connect 1 and 3 together and connect to negative, connect 2 to positive.

Note that it says 2 is connected to 'base'. I assume (you should check) there is a metal tab on the underside for cooling, I expect that this tab is connected to 2, so be careful not to short it to anything.
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 24, 2020, 11:10 am
Which country are you in? I think you said you are French, is that right? (Can't tell from your English, that's perfect!) Mouser is a US company, I was wondering if they are local to you or not.
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 24, 2020, 11:22 am
Ok, I will go with this one then! Thank you for the english compliment, better writting than speaking... :P

Ok, I see what you mean for the base, I will make sure this does not contact any other part of my system ;)

Thank you for all PerryBebbington! I do not know if I will find this one in France (Yes, I am in Toulouse), but I will find something equivalent I guess thanks to the datasheet of this one.

I guess that this topic is 100% solved, I will just send a message when I will have completed the system to just confirm it's working or not for the ones who would have the same issue as mine in the future ;) My Arduino program suits me. I need to begin the mechanical part now and receive some remaining parts.

Thank you again!! And see you soon for another topic maybe :P ;)
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 24, 2020, 12:06 pm
Quote
Thank you for the English compliment, better writing than speaking
Well, there's the thing with non-native English speakers; they learn English better than the English! Probably because, as a non-native speaker, you were not subject to a local English dialect. I speak 2 versions of English; the 'correct(!)' version and a local dialect. I imagine you know 2 versions of French; official French and some local version.

Is there a French component supplier? Or maybe you can use RS Components (https://uk.rs-online.com/web/) in the UK.   

Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 24, 2020, 12:22 pm
Ahah ok, I have noticed that, even in profesional world. Some english guys seem to not always follow the rules :P But as a french, I always have a doubt..

Yes, same in French, so many guys do so many mistakes, sometimes it is difficult to understand the sens of the sentence... I also talk a french special dialect but not all the words, just some expressions from the west of France (The Charentais!)

I will find a solution do not worry. Just needed the main charateristics of the component. Let's do the mechanical part now, I guess that in 1 month the whole system will be working! ;)
Title: Re: MOSFET N channel transistor curiosity
Post by: raschemmel on Feb 24, 2020, 05:03 pm
FYI,
A couple of minor details about nomenclature:

1.
Quote
MOSFET N channel transistor
Despite the fact that "MOSFET" stands for "Metal Oxide Semiconductor Field Effect Transistor", it is still
referred to as a 'FET' as opposed to 'transistor'.

In addition, it is referred to as an 'N-channel Mosfet', as opposed to 'Mosfet N-channel'.
I suspect this may be due to some language convention differences where the adjective follows the noun
as opposed to precedes it.

2.
Quote
the tension between the Drain and the + is around 8v.
In English , potential difference is called 'voltage', not tension. Again , I suspect this may be due to a
translation error.

3. Not sure what the English translation of 'alimentation (https://www.google.com/search?client=firefox-b-1-d&q=alimentation+definition)' means, but I suspect it means 'SOURCE'.
Title: Re: MOSFET N channel transistor curiosity
Post by: raschemmel on Feb 24, 2020, 05:19 pm
Are you unable to find a logic level N-channel mosfet (https://www.sparkfun.com/products/10213) ?

You might get better resolution using a higher frequency pwm signal (like 16 khz)

ARDUINO PWM LIBRARY (https://www.google.com/search?client=firefox-b-1-d&q=link%3A+http%3A%2F%2Fcode.google.com%2Fp%2Farduino-pwm-frequency-library%2Fdownloads%2Flist)
Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 24, 2020, 05:53 pm
I Raschemmel! Thank you for all these precisions ;)

Yes,  I am french, I have learned many new word right here, such as Power Supply (my alimentation= source), Voltage (for tension, for potential difference) and for the N channel stuff. Yo are right, nouns are not placed equal in french and english (english always do the wrong way, the same for car driving side :P :P :P, just joking...;))

I have finally found the good one for my application :) And yes, I have also seen that the medium voltage measured by my available tools is better and more constant when my frequency is higher.
For the moment it is 5kHz, I will see what happens with it in a first time. I am not keen on having a perfect speed control so it does not really matter to me to have some slight variations even if I should have the theoretical same motor speed following my Arduino program.
Title: Re: MOSFET N channel transistor curiosity
Post by: PerryBebbington on Feb 24, 2020, 10:32 pm
Quote
English always do the wrong way, the same for car driving side
Just remember that a lot of English speakers are Americans and they drive on the wrong side like you French do!!!!! :smiley-confuse:

Title: Re: MOSFET N channel transistor curiosity
Post by: 17Nico17 on Feb 25, 2020, 11:08 am
Ahah, yes, perfectly right :)
Title: Re: MOSFET N channel transistor curiosity
Post by: raschemmel on Feb 25, 2020, 03:57 pm
Let us not forget we are forever indebted to
the French for their kiss.
And they are  indebted to us for arranging it
so they didn't have to speak German.
Title: Re: MOSFET N channel transistor curiosity
Post by: MarkT on Feb 26, 2020, 04:38 pm
2. In English , potential difference is called 'voltage', not tension. Again , I suspect this may be due to a
translation error.
High voltage is sometimes called high tension in English, its not very common though.
Quote
3. Not sure what the English translation of 'alimentation (https://www.google.com/search?client=firefox-b-1-d&q=alimentation+definition)' means, but I suspect it means 'SOURCE'.
Pretty sure from context I've seen this it means specifically power supply (literally feeding).  Alimentary my dear Watson!
Title: Re: MOSFET N channel transistor curiosity
Post by: raschemmel on Feb 26, 2020, 06:02 pm
I'm not a lineman but I would guess that all high voltage lines are also high tension to prevent drooping of the heavy copper wires but supposedly the 'tension' term for voltage is a throwback from the early 1900s when 'tension' was used to
describe voltage.