Home     Contact     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science     RSS     Terms of services     Privacy policy  
   
 Home      Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science   

25 March 2010
Author: Giorgos Lazaridis
How DC Motors are made and how they work

In the following article, i explain the principles of operation of a brushed DC motor with permanent magnets. Also i show how a DC motor (with permanent magnets) is made and what is inside in such a motor. If you are interested in brushless DC motors, then better go to the page about how brushless DC motors work.




The Ampere's rule (the right-hand screw rule)

It is Frenchman Andre-Marie Ampere (17751836), a mathematician and physicist, who discovered what happens to a wire winded in a coil when current flows within. The current will generate a magnetic field around the coil, as shown in the following drawing:






The "right-hand screw rule"

Using your right hand, you can find out the direction of the magnetic lines as well as the North pole orientation. Close your fist and hold your thumb upwards, like thumbs-up. If you had the coil inside your hand and your fingers (except the thumb) was showing the direction of the current, then the thumb shows the direction of the magnetic lines as well as the orientation of the North pole. This is called "the right-hand screw rule".

The basic DC motor has actually two windings and two permanent magnets. The coils are powered from the commutator and the brushes. We will see these two later on. For now, you only need to know that during a full cycle of the rotor, the current that runs through each winding change direction once. Thus, each electromagnet will change its magnetic polarity. Moreover, the windings of the two magnets are winded in reversed direction. Thus, when one electromagnet is North, the other is South and vice versa. Look at the following drawing of the basic DC motor:





The following animation indicates how the two electromagnets changes magnetic polarity during a full rotation:





I have with RED color the North pole and with BLUE the South pole. If you watch this animation, you will see that there is one moment that both electromagnets are turned off. This is the time that the basic DC motor provides no torque at all. In all other occasions, the magnets are either PULLED from the opposite pole or PUSHED from the same pole and therefore the mechanical power is generated.




The commutator and the brushes of a DC motor

This kind of DC motor is called "Brushed DC motor". Why? Because it uses brushes... The brushes are the way that the motor provides the coils with power, and the geometrical characteristics and position of the brushes (and the commutator of course) will be responsible for changing the magnetic field of the two electromagnets according to the position of the rotor. So, how this is done? The brushes are two metallic pieces that act like springs. On one side, they have a piece of conductive material, usually made of carbon to stand against friction. On the other side, they have the pin that the power supply is applied to the motor. The brushes are pushed (by the spring action of the metallic part) against the commutator. The commutator is a metallic ring, also conductive and able to stand friction, that is divided in two parts. The following drawing explains how these parts are:





The commutator is fixed on the shaft of the motor. Each semi-ring has one pole of each coil. Giving thus power to both half-rings, is like giving power to the coils. But while the shaft of the motor rotates, the commutator rotates as well. This causes the poles of the power supply provided to the coils to change. This change of the electric poles, has an affect on the magnetic poles as well. The current direction is changed and - due to the rule of the right-hand screw - the poles of the electromagnets will also change. The following two animations indicates this procedure. The left one shows the brushes and the commutator from above, while the right one shows how the electric and magnetic polarity is changed.



Notice how each part of the commutator changes polarity as it rotates. This is the basic operation of the DC motor. Notice also, that there is one moment that the commutator is short-circuited. During this time, the motor produces no power at all, and also the short-circuit can cause several damages due to over current. This of course does not happen in real life. Later on, i will explain how this is avoided. Now, its worth to see this video that explains exactly how the DC motor is made:









Real life is different

This is a schematic drawing of the coil arrangement of a real motor.

Indeed it is. Nevertheless, the theory of operation is absolutely the same as above. What changes is the number of coils. Instead of 2, there are actually 3 coils that takes part. These 3 coils will solve the following 3 problems: First of all, there is no more this position that the commutators are short-circuited, and the motor will provide all the time torque, without the problems from over-current. Also, while in operation, always two or three coils will be active and interact with the permanent magnets. And because the coils have 120o angle between them, the torque provided by the motor is much more smooth and never falls to 0. Finally, if the motor had 2 coils and it was stopped in this position where the commutator is short-circuited, it would be impossible to start it again.

Of course, the 3 coils require now a different construction of the commutator. It is composed by 3 pieces instead of two, and the gaps are in circular pastern with 120o angle. The brushes are again two. The following animation shows how the real motor with the 3 coils works:





The way that the armature changes magnetic polarity is not that easy to understand as in the simple motor with 2 electromagnets. To understand the operation, you need to know first of all how the electromagnets are internally connected. The following image indicates this connection:





All electromagnets are winded with the same direction of rotation. Now, we have to distinguish two different situations as the motor rotates, The first situation, is when a brush is between two collectors. At this moment, all collectors are having power. During this time, one coil will have the same polarity between its poles, thus, this coil will NOT produce a magnetic a field as no current flows within.

The other situation is when one commutator piece has no power. This happens most of the time during the rotation of the motor. This commutator piece will act as a bridge for the two coils, that have one wire connected on it. Thus, these two coils will be considered as connected in series! And because their windings -as said before- have the same direction, they will both produce a magnetic field of the same magnetic polarity. The following two images indicates these two situations.


The piece of commutator that is black has no power. It acts like a bridge for coils 1 and 2. These coils are connected in series and they generate the same magnetic polarity. All commutators have power. This time, coil 2 has both its ends to the same electric polarity - NEGATIVE. Thus, coil 2 will produce no magnetic field at all.




Finally, let's see a real motor hos it is made!

I always like tearing things apart and see how they work!


The victim An exploded view of a DC motor. You can see the stator the rotor and the cover Inside the stator you can see the two permanent magnets, one opposite the other.
A close look on the rotor. The 3 electromagnets (armature) can be seen. Also, you can see the commutator, and -if you look close enough- you will see the gap between the contacts of the commutator. This is the cover from the inside. The brushes are fixed on the cover. The spring-action metal along with the brushes are visible. On the other side of each metal there is the power contacts of the motor. They go out of the cover Look close enough and you will see how the brushes are pushed against the commutator contacts.











Comments

  Name

  Email (shall not be published)

  Website

Notify me of new posts via email


Write your comments below:
BEFORE you post a comment: Long comments or comments of general interest are NOT to be posted here. Please use the forum instead. You will receive a reply much faster.


      

  • At 23 August 2014, 8:49:17 user Bijan Binaee wrote:   [reply @ Bijan Binaee]
    • Wow
      You've build great site
      thanks


  • At 13 August 2014, 18:17:54 user Syd Mitchell wrote:   [reply @ Syd Mitchell]
    • Why can't you increase V at max free spin to raise RPM, I hence EI and output ongoing? ( BDCM obeys V = E IR )
      Is this due to saturation of electromagnetic poles?


  • At 26 July 2014, 2:27:47 user Van Luan wrote:   [reply @ Van Luan]
    • First at all, tks your explanation so much!
      But i am wondering with question?
      some DC Motor has an extra housing although it already had a housing as your video
      What is the purpose of this extra housing???


  • At 14 May 2014, 16:55:50 user Engr.M.Shahbaz bashir wrote:   [reply @ Engr.M.Shahbaz bashir]
    • I got valuable information


  • At 21 April 2014, 2:48:35 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Emmanuel Dinampo Overcurrent/mechanical stuck on the shaft are possible causes.


  • At 20 April 2014, 4:53:59 user Emmanuel Dinampo wrote:   [reply @ Emmanuel Dinampo]
    • we had a dc 125 motor was tested by electrical personnel on no load and it was damaged,the commutator and the brushes blown out? what was the causes?


  • At 7 April 2014, 23:55:15 user Himanshu wrote:   [reply @ Himanshu]
    • Amazing explanation. After exploring all sites..my search ended here.. :)


  • At 18 February 2014, 21:46:19 user Shahzad Ahmed wrote:   [reply @ Shahzad Ahmed]
    • Thanks for giving a lot of information here.


  • At 4 February 2014, 3:03:23 user ntombenhle sibiya wrote:   [reply @ ntombenhle sibiya]
    • i love this i need more keep up the good work


  • At 5 January 2014, 19:32:26 user Ana wrote:   [reply @ Ana]
    • Amazing explanation with words, draws and videos!! Woooww!!!
      Thanks!!


  • At 30 December 2013, 10:36:25 user Doyle wrote:   [reply @ Doyle]
    • What deter mans if it's a 12 or a 95 volt. The windings on the armature , just wondering


  • At 29 November 2013, 23:28:31 user yasser mohammed wrote:   [reply @ yasser mohammed]
    • thanks really nice explanation keep on


  • At 2 November 2013, 14:30:08 user Vince Kasprzak wrote:   [reply @ Vince Kasprzak]
    • Traditionally, the Lorentz force is used to explain the force on the motor's armature. Your explanation uses the attraction between the field magnets and the armature as it's considered to be an electro-magnet. Do you consider this to be equivalent to the Lorentz force, and if so how?


  • At 16 October 2013, 22:36:06 user Carl Fleming wrote:   [reply @ Carl Fleming]
    • Sirs:
      Under your 'DC Motor' page and then under the heading, 'Ampere's rule' you talk about the "Right Hand Rule"

      The correct rule is the 'Left Hand Rule'.

      From 'Understanding Radio' copyright 1941, 1951, 1960 by McGraw-Hill Book Company. Authors: Herbert M. Watson, Herbert E. Welch and George S. Eby.

      The reference 'Left Hand Rule' is stated in the 1960 copyrighted publication; Chapter 4, page 59, 'Magnetism and Direct-Current Meters', "How is the left-hand rule used?".

      The Left Hand Rule is also addressed in many other publications about motors, electronics.

      Yours.
      Carl Fleming


  • At 8 October 2013, 9:52:17 user shiva kumar wrote:   [reply @ shiva kumar]
    • good explanation. thanks:)


  • At 25 September 2013, 1:31:47 user ajithesh wrote:   [reply @ ajithesh]
    • very well explained,
      thanks!!!


  • At 30 August 2013, 9:32:30 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @marc What type of motor is that? AC squirrel cage?


  • At 18 August 2013, 17:26:31 user Roger wrote:   [reply @ Roger]
    • What is the relationship between lenght of the motor and components and the diameter?


  • At 12 August 2013, 12:58:29 user marc wrote:   [reply @ marc]
    • @Giorgos Lazaridis i wanted to see if you could help us troubleshoot something, we're working on a project our goal was to build a clear dc motor. we took apart a new starter motor from a car and had a piece lexan tube machined to the same specs as the original motor casing but when assembled and bench tested the motor it dosent opperate smoothly. it sounds as if the timing is off, if the electro magnet fields are off slightly will it cause this? thank you for any help you can offer


  • At 10 August 2013, 6:48:52 user yuvaraj wrote:   [reply @ yuvaraj]
    • nice explane


  • At 30 July 2013, 1:09:43 user Zbigniew Wojciechowski wrote:   [reply @ Zbigniew Wojciechowski]
    • I need animation for 4 polar stator from permanent magnets and winding on rotor (armature).


  • At 23 June 2013, 6:40:43 user Ritesh wrote:   [reply @ Ritesh]
    • Thanks for such a nice explaination


  • At 14 June 2013, 3:42:06 user Didar wrote:   [reply @ Didar]
    • very good description....& well designed... & will be very helpful to electrical engineering students.. or who is interested in electrical......


  • At 11 June 2013, 0:15:29 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Zach this depends on the direction that the coils are winded. The point is that -whatever the current direction or coil- there must be a south and a north pole.


  • At 9 June 2013, 11:37:48 user Zach wrote:   [reply @ Zach]
    • Hello, Thank you for the great video and explanation on dc brush motors. However, I did have one question regarding the direction of the current. In regard to the two coiled motor you used in the video,would the current be going in the same direction for both coils thus making the north and south poles for both coils be in the same direction?


  • At 2 April 2013, 13:11:47 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @ganesan Is it a stepper motor? Check out my "stepper motor theory page"


  • At 2 April 2013, 12:00:57 user ganesan wrote:   [reply @ ganesan]
    • I am facing one problem there are six wires in one dc motor. Iwant to change the direction normaly i try to change the armature connection then no more change in direction. How can i change the direction pl. give a good sugestion. thank you.


  • At 13 February 2013, 21:08:46 user KCManiac wrote:   [reply @ KCManiac]
    • Well, I don't know about this. It was hard for me to follow. What would be more explanatory to me would be for a sine wave super-imposed onto the brushes because this is where the AC is applied to the "commutator". Because of the change in magnetic poles due to the alternating current through the brushes it creates a "repelling(north vs north and south vs south) and attracting(north vs south or south vs north)" characteristic of magnetism which then causes electromagnetic induction onto the coil in the rotor only to then be applied against the stator (permanent magnet of motor which is aligned to be the opposite) to again create the opposite poles and thus turns rotor to continue the movement. A change in AC voltage to the commutator will dictate the RPM of the rotor. The lower the voltage the slower the rotor. So what is happening is that three phase current (basically north vs north OR south vs south happens three times a cycle or 180 times per second) is changed into DC thus continuous movement of rotor. Once again for all this to be understood you need to compare the position of of the rotor to the sine waves of the incoming AC current which in most cases is going to be three phase.


  • At 8 February 2013, 6:19:02 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @H Chris Spreckley This tutorial is for DC motor. i have this strong feeling that you're talking for the poles of an AC motor, is that correct?


  • At 5 February 2013, 9:21:20 user H Chris Spreckley wrote:   [reply @ H Chris Spreckley]
    • @Sumeet Pahw
      Hi I think I have absorbed all you have had to say on 3 pole electric motors howsoever I am slightly confused on magnetism as I am at the happy age of 72 a railway modeler and I find that my best running engines definitely go best when they are fitted with 5 pole motors.

      Now the question please: I believe that a 5 pole motor can run within the same field coil as a 3 pole. If this is true how is that please? Else: how are five differing magnetic fields produced in 360 degrees from a circular magnet; an even number I might just understand but an odd number doesn't seem conducive to conservativeness field production.
      Hope you can help me,
      H Chris Spreckley.
      England.


  • At 16 January 2013, 7:42:15 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Roland Joseph to flip the magnetic polarities when needed. AC motors do not need one cause AC flips alone.


  • At 14 January 2013, 15:31:57 user Roland Joseph wrote:   [reply @ Roland Joseph]
    • can someone help.. Why a DC motor has a commutator and not slip rings.
      and someone post the aswer in commments.. thanks


  • At 14 November 2012, 23:19:04 user Jeff wrote:   [reply @ Jeff]
    • Very clear explanation.
      Thank you very much for making this.


  • At 10 November 2012, 11:52:24 user Gauta wrote:   [reply @ Gauta]
    • Hey guys I'm artisan electrician I would like to know futher about DC machines thanks


  • At 22 October 2012, 8:42:28 user Negg wrote:   [reply @ Negg]
    • Graphics used and the video made me understand everything completely. I spent 10 minutes surfing the web and this tutorial was the best I could find on brushed DC motors. Wonderful job! Thanks!


  • At 29 September 2012, 4:20:23 user priya wrote:   [reply @ priya]
    • fantastic job sir. its very clearly understood by me and i had read about the realys in the same website 2 months ago really its fantastic that i did not forget. i dnt have much memory power bt it feels so swet thst i can remember by seeing pics n videios explained in this manner. thnk you so much for providing such a great website fot the students like us


  • At 26 September 2012, 15:55:55 user Ricardo wrote:   [reply @ Ricardo]
    • I love you so much!!! this is the best description of how a stepper motor works that i have seen ! thank you for everything!


  • At 17 September 2012, 6:37:20 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Shane what really matters is to have the proper magnetic polarity. so, either the coils are winded as you said, or the coils have the same winding direction but different current polarity.


  • At 17 September 2012, 6:20:45 user Shane wrote:   [reply @ Shane]
    • Hey just wondering, for your two pole motor, are both coils wound the same way or is one clockwise and the other anticlockwise? Cheers


  • At 8 August 2012, 23:21:05 user vivek wrote:   [reply @ vivek]
    • nicely created animation..thank you..!


  • At 2 August 2012, 9:47:13 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Concy normally, the energy that the motor will get from the permanent magnet during impulsion will be the same during attraction, so the total E will be zero... But i cannot tell for sure.


  • At 2 August 2012, 8:43:04 user Concy wrote:   [reply @ Concy]
    • @Giorgos Lazaridis

      It is possible to actually create a motor using permanent magnets?

      I have seen videos people using cpu fan and permanent magnets are working. Is it real or fake.
      http://www.youtube.com/watch?v=7PDeK6rprA4&feature=related


  • At 8 July 2012, 4:13:47 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Rajesh because we either need a rotating or a switching magnetic field. Nevertheless, there are many people who tried to make a motor only with permanent magnets


  • At 5 July 2012, 5:30:42 user Rajesh wrote:   [reply @ Rajesh]
    • Why don't we use fully of permanent magnets to run a motor


  • At 29 May 2012, 0:11:23 user mou wrote:   [reply @ mou]
    • Nice, thank you.


  • At 8 April 2012, 18:03:47 user daleela wrote:   [reply @ daleela]
    • thank you very much. i doing presentation on this and yours explanation is way better than others in the internet.


  • At 24 March 2012, 11:36:59 user saon wrote:   [reply @ saon]
    • thanxxxxxxxxxxx
      really helpful


  • At 17 March 2012, 8:44:53 user Noctis wrote:   [reply @ Noctis]
    • Very understandable explanation, helped me a lot ;)
      -N


  • At 8 March 2012, 7:08:49 user nafis nfs wrote:   [reply @ nafis nfs]
    • this is a great site about knowing how electric equipments are made...As a science student i appreciate it.... Go on pcbheaven.com....


  • At 23 February 2012, 23:42:18 user NIKHIL PATEL wrote:   [reply @ NIKHIL PATEL]
    • Dear Sir,

      Nice to see ur video, good explanation.

      we are manufacture AC submersible motor pumps set since 25 years, right now we have demand 3", 4", 6" DC submersible motor.

      I would like to know how to made DC bruselles motor in submersible application.

      I want to run this motor from the Solar panels.

      Please give me idea how can i built up dc motor.

      Thanks
      Nihkil Patel


  • At 24 January 2012, 8:20:25 user gautham wrote:   [reply @ gautham]
    • @rohan mukherjee

      I hope i'm not complicating things., But you see electric field creates flux around the winding, which forms concentric loops ,UNLIKE magnetic flux which gets from Point to point i.e NOrth to south. Thus this Interaction; i.e The straight flux(magnetic)while passing from North to Souch PUshes This circular moving(concentric) flux Along the way, creating a rotating force(Torque) which inturn rotates the coil..


  • At 24 January 2012, 8:09:33 user gautham wrote:   [reply @ gautham]
    • Just one doubt: You say 120 degrees..does that mean a Pulsating 120 degrees?? i.e one cycle 120 degree pulse?


  • At 20 January 2012, 7:10:15 user S.NandhaKumar wrote:   [reply @ S.NandhaKumar]
    • nice Presentation and the explanation of Dc Motor


  • At 18 January 2012, 10:12:18 user Kammenos wrote:   [reply @ Kammenos]
    • @nicole you can see the animation at section "Real life is different" of the document which shows exactly this.


  • At 18 January 2012, 9:48:09 user nicole wrote:   [reply @ nicole]
    • how do they switch the power between those three brush's commutator


  • At 13 January 2012, 12:59:43 user roushan kumar mgr clg wrote:   [reply @ roushan kumar mgr clg]
    • thanks sir ,it is realy nice to understand the real concept of how does a dc motor work ?


  • At 11 January 2012, 3:53:16 user J.BHIMARAO RAMJI wrote:   [reply @ J.BHIMARAO RAMJI]
    • verry supper animation sir

      thank you


  • At 9 November 2011, 4:24:59 user Hemal wrote:   [reply @ Hemal]
    • wow, great tutorial.
      Can you tell me which software you used in the video 'DC motors - how is it made? How it works? '
      Thanks


  • At 3 November 2011, 9:08:23 user saka wrote:   [reply @ saka]
    • Very good


  • At 2 November 2011, 9:08:01 user seal team wrote:   [reply @ seal team]
    • nice work !!!!!!! tanx a lot


  • At 23 October 2011, 15:04:35 user Mustafa Adwan wrote:   [reply @ Mustafa Adwan]
    • thanks alot
      this is the best way to know how electrical equipments work
      please keep going


  • At 12 October 2011, 13:31:15 user Charles wrote:   [reply @ Charles]
    • that was well explained thank you


  • At 12 October 2011, 10:06:06 user Kammenos wrote:   [reply @ Kammenos]
    • @rohan mukherjee when current flows in a wire, it creates magnetic field. The only interraction between electromagnets and permanent magnets is the magnetic repulsion/impulse, but this is due to the current that flows within the electromagnets.


  • At 11 October 2011, 13:50:58 user rohan mukherjee wrote:   [reply @ rohan mukherjee]
    • ok electromagnets have that amazing prop of changing magnetic pole directions.but tell me is the rotation only due to magnetic attraction and repulsion or due to currents in magnetic field..pls email me..nebdy..

      rohan.mukherjii@gmail.com


  • At 11 October 2011, 12:30:54 user rohan mukherjee wrote:   [reply @ rohan mukherjee]
    • thnx a lot..helped a lot..bt how electromagnets and permanent magnet magnet interact yielding force in aniclock or clock direction was not clear. But understood the general principle of permanent magnet and line current and force associated with that. also was not clear why use electromagnets ??


  • At 16 September 2011, 1:31:11 user Maddy wrote:   [reply @ Maddy]
    • pls make some animation for the The Ampere's rule (the right-hand screw rule) and show the flow of current and force acting .


  • At 13 September 2011, 18:30:13 user nachtan wrote:   [reply @ nachtan]
    • A really _excellent_ presentation. Very clear. Your diagrams along with the verbiage explaining them helped a lot.

      I wish my early teachers had been this clear.

      Thank you. (I'll look for more).


  • At 28 August 2011, 5:04:09 user Sruthi wrote:   [reply @ Sruthi]
    • thankyou for the video.....it helped me understand the structure better...


  • At 13 August 2011, 12:44:27 user claudio wrote:   [reply @ claudio]
    • Don´t worry about your accent . It´s ok . If somebody puts you down about that .I wonder how he or she would speak a foreign language . Anyway good job chap , keep going , your explanation is very clear . thanks a lot ..............


  • At 5 August 2011, 0:25:14 user nebro wrote:   [reply @ nebro]
    • excellent work indeed


  • At 15 June 2011, 8:40:08 user M44 wrote:   [reply @ M44]
    • Awesome!!! Could you similarly explain the working of DC Generator


  • At 10 June 2011, 23:56:18 user Himansu Sekhar Satpathy.Orissa wrote:   [reply @ Himansu Sekhar Satpathy.Orissa]
    • Sir,
      Nicely designed.Maximum clarity,Objective oriented,Well understood.
      Lot of thanks to you SIR.


  • At 21 May 2011, 5:42:21 user Eng , Majdi wrote:   [reply @ Eng , Majdi]
    • Great Work ... you must be a professor man ... this how teachers must teach students ...


  • At 18 May 2011, 2:56:57 user himesh wrote:   [reply @ himesh]
    • great, very very excellent work ,marvellous


  • At 9 April 2011, 4:03:46 user Boris wrote:   [reply @ Boris]
    • Just awesome! Watched all youtube clips about it!! It was easy to understand everything from practical point! Thank you GJ!


  • At 15 February 2011, 20:03:17 user muqtar wrote:   [reply @ muqtar]
    • Great ! I cant express how good u r at this,u have done an excellent job.a vry practical way of teaching.Thanks a lot.May ALLAH bless u..


  • At 28 January 2011, 11:51:25 user rock wrote:   [reply @ rock]
    • I thank God for appointing you as an excellent teacher. I need not search for so many other websites. Even a child can very well learn by your teaching without any doubt. I feel as if i am attending real class room. your really very much talented and let your talent be recogonised by the entire world. I expect more and more from you on different kinds subjects. May God bless you with long life. Hats off to you. warm regards.


  • At 13 January 2011, 20:52:15 user Sumeet Pahwa wrote:   [reply @ Sumeet Pahwa]
    • Your way of teaching is teraffic. Even in N.I.T. india this type of education is not provided. You are real teacher and hats off to you!


  • At 8 January 2011, 4:28:31 user dost arora wrote:   [reply @ dost arora]
    • oh my good .....its the best way of teaching...thank u....i understand so much from this


  • At 27 December 2010, 6:30:45 user soumya wrote:   [reply @ soumya]
    • pls explain the alternate way of working of bldc motor without using hall sensors


  • At 7 December 2010, 19:56:55 user Murphy wrote:   [reply @ Murphy]
    • Thanx so very much. Now u have given us practical knowlegde. Something we dont get easily during learning. U are the bomb Man! Keep it up!


  • At 2 December 2010, 6:58:55 user mohammad wrote:   [reply @ mohammad]
    • thank you man you make it very easy
      keep going.....


  • At 6 November 2010, 9:58:43 user Palash Jyoti Borah wrote:   [reply @ Palash Jyoti Borah]
    • very very attractive way of teaching... This is my first visit to this site.. and I say it\'s wonderful... The way of interaction is perfect... I beg you please go along in this fashion and provide us knowledge through practical experience.. Indeed, I would vote this site as my favorite site..Thankssss....


  • At 26 October 2010, 10:11:29 user viraj damani wrote:   [reply @ viraj damani]
    • thank you sirrrrr....cann''''t expect more from this explanation...fabulous...keep it up


  • At 14 October 2010, 12:24:01 user cory wrote:   [reply @ cory]
    • i need to no how to build a fast 6 pole motor any one can help i would love u long time cuzz i am building a bendini g-field generator i can help u build one of them if you would like


  • At 11 October 2010, 9:56:17 user Kammenos wrote:   [reply @ Kammenos]
    • wogga, my English is good enough to write something, yet its bad enough to write it absolutely correct. Sorry for such mistakes.


  • At 11 October 2010, 7:49:19 user wogga wrote:   [reply @ wogga]
    • maybe it's some electrical term, but most of say "wound" not winded.


  • At 24 September 2010, 20:29:44 user chandan wrote:   [reply @ chandan]
    • Thanks a lot.no doubt now.Pls keep on working like this............


  • At 15 September 2010, 23:26:43 user Mal wrote:   [reply @ Mal]
    • Great bit of work. Couldn't have found a better simple explanation. Thanks a lot.


  • At 7 September 2010, 5:43:34 user amirhosein hadi wrote:   [reply @ amirhosein hadi]
    • hi
      I want to join your site


  • At 21 August 2010, 0:56:29 user Azhar Zaidi wrote:   [reply @ Azhar Zaidi]
    • Marvelous work. I am personally grateful to you for explaining a complex machinery in such a simple manner. Thanks again


  • At 16 July 2010, 12:12:39 user Greg wrote:   [reply @ Greg]
    • Very thorough explanation, drawings and animations.


  • At 9 June 2010, 11:34:24 user ben wrote:   [reply @ ben]
    • thanks


  • At 7 April 2010, 16:14:17 user Stu wrote:   [reply @ Stu]
    • Using computer animations like you did, along with clear narration, is a really great way to explain how these things go together!
      Awesome work and thanks so much for so clearly explaining something I\'ve been mystified by for a long while!
      And I didn\'t think your accent spoiled anything, you\'re quite understandable.
      Thank you!


  • At 30 March 2010, 0:09:54 user Jdaddy wrote:   [reply @ Jdaddy]
    • Nice animations dude!


  • At 27 March 2010, 10:56:34 user Kammenos wrote:   [reply @ Kammenos]
    • Thank you Ted, much appreciated!


  • At 27 March 2010, 6:07:19 user Ted wrote:   [reply @ Ted]
    • Commutator?





    delicious
    digg
    reddit this Reddit this
    Faves



     HOT in heaven!


    NEW in heaven!



    New Project: Lab Power Supply 0-20V 10mA-2A



     Contact     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science     RSS   

    Site design: Giorgos Lazaridis
    © Copyright 2008
    Please read the Terms of services and the Privacy policy