DC Motor
Just a press of a button and an elevator can transport you from the ground floor of your apartment building to the top floor of Burj Khalifa. That’s the power an elevator has. But, have you ever wondered from does it get this power to transport a mass as heavy as 500kg in a matter of seconds? Well, behind the curtain is the powerful machine that is responsible for helping the elevator move up and down; it is called the DC Motor.
Any motor, in general, takes in electricity from one end and uses it to rotate the rod at its other end. The rod can be connected to some other machine that works when it rotates. A DC motor is no different.
Components of a DC Motor
Let’s unfasten one to find out what makes it possible for the motor to move such huge elevators. A DC motor has two essential components:
- A magnet on the edge of the motor body that remains static and is hence called the stator.
- A coil of thin wire placed in slots on a cylindrical object known as the armature. In a DC motor, the armature rotates when it receives electricity. Therefore, it is called the rotor. The rotor is placed between the north and south poles of the magnet. The two ends of the coil are connected to a component known as the commutator.
The current enters the motor through the coil placed on the rotor. The rotor due to the presence of the magnets starts rotating, thus converting electrical energy into rotational motion.
We can find DC motors in many devices that we use at home, such as vacuum cleaners, hair dryers, laptops, toys, and razors.
Controlling DC Motor with evive
Enough of theory; time for some learning by doing! Take out your evive and starter kit. We’re going to see motors in action!
- In the starter kit you’ll find two 2 dual shaft motors that look like this:
Take one out and keep it aside. - Now, take evive. On one of its side, you’ll find four pins at the leftmost edge M1 and M2 written above them. The upper pair of pins is motor channel 1 or M1, and the second pair is motor channel 2, or M2.
Take the motor that you kept aside and insert the wires attached to it in the first motor channel, i.e. M1. Now, switch on your evive. The first option in the menu that appears on the screen is Controls; select that option by pressing the control button to the right. Once you select it, you’ll see three more options, namely Motors, Servos, and Stepper Motors; select Motors. - From the three options that now appear on the screen, select Motor 1 & 2. The following screen will appear::
PWM refers to the electrical signal (output from evive) that the motor takes in through its wires. It can be controlled using the two potentiometer knobs; knob 1 controls the PWM signal at channel M1 and knob controls the PWM signal at channel M2.
Dir1 and Dir2 are the two possible states or the two possible directions in which the motor can rotate; Dir1 represents clockwise and Dir2 represents anticlockwise. The two slide switches that are on the right of the knobs control the direction; when in centre, no direction is selected. If the switch is up, then Dir1 is 1, i.e. the direction is clockwise, and Dir2 is 0. But, if the switch is down, then Dir2 is 1, i.e. the direction is anticlockwise and Dir1 is 0. Same as the potentiometer knobs, the 1st switch sets the directions for the motor connected to M1 and the 2nd switch sets the directions for the motor connected to M2. - Coming back to business: controlling the motor. Once you’ve connected the motor, slide the switch upward; on doing so the motor shafts will start rotating. Now, rotate the potentiometer knob in the clockwise direction; as you do so, you’ll observe that the speed of rotation of the two shafts of the motor becomes. It reaches the maximum when the value of PWM is 255. If you slide the switch down, the shaft will start rotating anticlockwise.
Activity 3.1: DIY Turntable
This time we’re going to go step a little out of the line and bring a little bit of art into our safari at this stage. How? By making a turntable. A turntable is a very useful device. It is a rotating circular disc that is generally used to play the big black music records; getting a bit creative with it, though! It can be used for making a beautiful drawing, and for displaying products. A potter’s wheel can be considered to be similar to a turntable which rotates quite fast.
We’re going to make a mini turntable of our own using one of the DC motor available in the starter kit and evive.
What you need:
- A DC Motor
- A cable tie
- 2 male-to-female jumper wires
- A wheel
- Chassis/base plate
- Our old friend, evive
- A discarded CD or a circle of diameter 15cm cut out from a piece of cardboard
- Removable glue e.g. hot glue
- A circle of diameter 15cm cut out from a piece of paper
- Some sketch pens or colorful pens
Everything from the motor to evive is available in the starter kit and you’ll find the rest at your home. Moreover, without wasting any more time, let’s begin!
What you must do:
- Take the wheel (not the steering wheel of your car!) and stick it in the centre of the CD or the circle cut from the cardboard using removable glue. Next, paste the circle cut out from the paper on the other side of the CD. In case you’re done place it aside.
- Then, take the chassis, the DC motor and the cable tie. Place the DC motor on top of the chassis, near its end, and fasten it using the cable tie. Make sure that the shaft one side goes through one of the holes on the chassis. Refer at the figure given below in case you feel confused:
- Next, take the wheel and CD assembly and fix it on top of the motor by inserting the shaft into the wheel.
- Take the two male-to-female jumper wires and connect their female ends to the pins of the first motor channel, i.e. M1. Then, take their free male ends and connect them to the two wires of the DC motor. And it’s all done. Time to make some art!
- Switch on your evive, and as done before, from the menu select Controls. Navigate all the way and select Motor 1. Next, select a direction by sliding the switch upward. Henceforth watch the turntable rotate gracefully by rotating the potentiometer knob and setting it at a particular value.
- As the turntable rotates, place the pen or the sketch pen anywhere on the circular disc and watch as different, beautiful patterns unfold!
