switching pole electromagnet project help

Discussion in 'The Projects Forum' started by Jason27, Nov 21, 2015.

  1. Jason27

    Thread Starter Member

    Nov 15, 2015
    31
    1
    hi everyone, would like ideas/help for a simple if possible 12v circuit that i can use to switch poles on my electromagnet for a demonstration electric motor. i don't know the amount of winds or wire size(looks like 2mm)has a resistance of 2.7 ohm's. i don't mind if it overheats a bit as I'm going to use it for short periods of time only. I've been using the electromagnet on a 12v 2.5amp,hr battery, but i need it to switch poles with variable speed control would be nice.
    i have (if it helps) a few bc337,2n3055 and a mje3055 transistors handy.ill buy if needed of course.
    appreciate the help.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    You need an H-bridge.

    What signal causes the polarity to switch? Are you expecting to just use an asynchronous oscillator (multivibrator), or do you want to "commute" the motor by synchronizing the polarity switching with the shaft position?
     
    Jason27 likes this.
  3. Jason27

    Thread Starter Member

    Nov 15, 2015
    31
    1
    Hi MikeML
    either would do as long as it spins, I'm guessing commute would be better? is that using a hall effect switch?if so i can only get the ugn3503u, op voltage 4.5-6vdc
    current 9ma
    output 2.5v
    output res 50ohm's.
    whats would you suggest?
     
  4. Jason27

    Thread Starter Member

    Nov 15, 2015
    31
    1
    just trying to make a simple in runner motor. i have 2 of the same electromagnets if that makes it easier.
     
  5. RichardO

    Well-Known Member

    May 4, 2013
    1,230
    382
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,509
    2,369
    Electronic commutation requires some kind of sensor to detect armature position together with switching circuit, the simplest way to commutate is using the DC motor method of using rotating coils that carry the contacts for the applied power, see bar commutator.
    Max.
     
  7. Jason27

    Thread Starter Member

    Nov 15, 2015
    31
    1
    thanks for replying guys, Richard i understand the principles of the motors I'm just not to good at making circuits, lol
    i want to get away from brushed motors. as you can see in my first post there is a picture of the basic motor housing, it uses a single electromagnet. i wanted to obtain a circuit that will change polarity of the electromagnet when the hall sensor passes the magnet (desired but not a must). i have 2 of these electromagnets so i can also use one opposite sides of the motor. I'm using 12v and the only hall effect switch i can get is the ugn3503u, with a
    op voltage 4.5-6vdc
    current 9ma
    output 2.5v
    output res 50ohm's.
    the diagram below is what i'm guessing i need but the hall sensor in this pic is a 12v unit and don't have the smarts yet to determine the modifications needed to use the 6v sensor.
    i've also added a pic of a similar motor of what I'm trying to achieve.
    tnx guys. 82925-9706cdf3a939bda19db25c06b1967a08.jpg 82924-bc429196dea9fbc80578a9220dcbaeb2.jpg
     
  8. Jason27

    Thread Starter Member

    Nov 15, 2015
    31
    1
    H-bridge worked perfect, tnx for the advice.
     
Loading...