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    element14's The Ben Heck Show

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    Max steps back from the camera to learn about motors, motor drives, and switches from Felix. Felix takes apart a Motor and they work on a basic H-bridge circuit made from P-channel MOSFETs controlled by NPN Transistors.



    Felix gives Max a lesson on how motors work and how to control them. There are a bunch of different types of motors.  There are DC motors and AC motors with various phases.  Felix goes over DC motors with Max. He shows one that has a permanent magnet and draws a picture of one with a field winding known as an electromagnet stator.  The field winding goes to the armature. There are positive and negative leads on each side. There’s a stator and a rotor, depending on which of your two leads is negative or positive, will determine the direction that the rotor turns, either clockwise or counterclockwise.


    Next, Felix takes apart the motor with a permanent magnet to see what’s inside. The two large magnets are stationary inside a large housing. The rotor has contacts down at the bottom that meet with these brushes so they come out to eternal. The power goes into one terminal, meets up with a contact on one side, goes through a coil and creates an electromagnet inside. The brush meets on the other side through the solar contact so that the electromagnet is energized and the poles are in a certain position.  The permanent magnets act in opposition to the magnetic poles of the electromagnet and it causes a rotation.  As it rotates, there’s a break in all the contacts, so as the motor turns on those brushes it inverts the magnetic pull, thus causing it to continue spinning. Now that Max is informed on what is in a DC motor, it’s time to teach him what an H-Bridge is.


    Felix and Max work on a basic H-bridge circuit made from P-channel and N-channel MOSFETs controlled by NPN transistors Felix lays down the components they are using for the H-bridge They have a couple of 2n222 alpha transistors a couple of  IRF630IRF630 N-Channel MOSFETs and a couple of IRF9630 N-Channel MOSFETs They’re also going to need some resistors and a few other components but they’ve got the layout of the H-bridge organized An H-bridge takes a voltage and reverses the voltage sent to the different terminals of a motor They can turn it in one direction stop it and turn it the other direction Max familiarizes himself with the circuit by building it on a breadboard


    Once Max has a working H-bridge, his next question for Felix is how to transfer it to his perf board. To do this they’ll need two P-channel MOSFETs, two n-channel MOSFETs.  Felix finds this and all additional parts they’ll need so that he can demonstrate what you need to do.  He does a layout that consists of two inputs, a motor, power, and ground.  He’s working off of a schematic but the layout will be different on a perf board. Max attempts to cobble up an H-bridge by taking Felix’s breadboard and referencing the schematic. The breadboarded circuit is an R/S latch to provide input for the H-bridge.