One way it to use the Double Pole Double Throw relay switch. The diagram for this lab contains a DPDT relay switch controlled by a TIP120 transistor to reverse the direction of the motor. This approach requires a dual 5-Pin relay that control this process. The first pin starting with the coil is the mechanism that does the physical switching once power is applied to these terminals. The second pin is called the Normally Close for when the switch poles are not activated. You can say this is the passive switch position when the is no power to the coil. The third pin is called the Common and is the pole that moves or pivots when activated, also a power supply is suppose to go here too or a signal. The fourth pin is called the Normally Open, because in its passive, unpowered state the poles of the switch are not touching it and are therefore an open circuit. The fifth pin is called Not Connected and its function means just that, the pin is not connected to the switch, so we don't use this one. It is very important to know the functions of every pin on the relay or else you will be super confused and randomly connect anything and hope something happens.
Another way to reverse directions for a DC motor is to use a circuit called an H-Bridge. It is called this name because there are four switching elements at the corners of the "H" and the motor makes up the horizontal line of the H. Usually the top part of the H is the positive pole and the bottom is the negative pole where power is supplied. There are two other inputs on the left and right side of the H-Bridge. The left input is connected to the two transistors located on the left side of the H from the top and bottom. The right input has the same connection, but to the Right top and bottom transistors. The H-Bridge contains two NPN transistors (MPSA 13), two PNP transistors (MPSA 64), four diodes (1N4001), and four resistors (3.3Kᘯ) to protect the transistors from burning out. The switches are turned on in pairs from high left to lower right of the H, but never on the same side. Anything that can carry a current will work such as: four SPST switches, one DPDT switch, relays, transistors, and MOSFETs. I believe there are other applications besides reversing the direction of a DC motor. The H-bridge can be configured to use all four switches independently and make a four quadrant device.
Demonstrate DPDT Relay Controlling Motor
Materials:
- 1KΩ resistor
- TIP120 transistor
- DPDT relay
- DC motor
- 1.5V C battery
- Battery holder
- Breadboard
- Wires/Leads
- 5V power supply
We are to build the schematic shown in lab manual. It consists of the ON/OFF switch lead connected to a 5V power supply to the 1KΩ resistor, which is then connected in series to the TIP120 transistor. The collector pin is connected to the Common pin of the DPDT relay. The emitter pin is then connected to a pin on the relay that powers the coil. the opposite pin connect to the coil goes to the ground. The 1.5V battery's positive terminal connects to the Common on the relay that is opposite of the collector connection. The negative terminal on the battery goes to the ground. The left Normally Closed pin of the relay is connected to the right Normally Open pin. The left Normally Open pin is connected to the right Normally Closed pin. The DC motor is also connected to the left Normally Open pin and also to the right Normally Closed pin. As we see here the Normally Open pi is connected to the opposite Normally Closed pin and vis versa to reverse the direction of the motors spinning. But once the wire that is connected to the 5V power supply is disconnected the relay returns to its passive state and switches the direction of the motor. The coil is thus activated whenever connected to a 5V power supply thus switching the direction of the motors spin like an On and OFF button.
Demonstrate H-Bridge Circuit Controlling Motor Using 5V Power Supply
Materials:
- 4 x 3.3KΩ resistors
- 2 x PNP transistors (MPSA64)
- 2 x NPN transistors (MPSA13)
- 4 x 1N4001 diodes
- DC Motor
- 1.5V battery and battery holder
- Breadboard
- Wires/Leads
- 5V power supply
We build a very basic H-Bridge schematic with two inputs at the left and right side, and the DC motor is connected between the top and bottom half of the H-Bridge. The bottom half of the H-Bridge circuit use the bottom portion of the breadboard's ground bus and the top half of the circuit is connected to the top portion of the breadboards ground bus. Connecting the H-Bridge to bottom ground bus the top 5V power supply bus is very important. The 1.5V batter continuously runs the DC motor, while connecting the 5V power supply's positive terminal to either the top or bottom half of the bread board reverses the direction of the DC motor. This is very similar to the previous lab.
Demonstrate H-Bridge Circuit Controlling Motor Using Arduino
Materials:
- PCB H-Bridge or Breadboard H-Bridge
- 1.5V DC motor
- Arduino
This lab is very similar to the previous, but for a few minor differences The wire that connects the upper and bottom portion of the breadboard is now replaced by two more wires that are connected to the Arduino's pin 12 and pin 13. Also the Arduinos ground pin is connected to the breadboard. Pin 12 will be programed to turn ON for 2 seconds with a 1 second STOP delay and pin 13 will turn ON for 2 seconds with a 1 second STOP delay.
Supper cool!!!! Right!?!?!
No comments:
Post a Comment