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Physical Computing



Computational Media


      Physical Computing

      Week 01





      Lab Activities
      + Parts and Tools Guide

      Related Videos

      Readings







      Electricity : The Basics

      Definitioins

      • Electricity : flow of electrical energy through conductive materials.

      • Sensors : components that convert other forms of energy into electrical energy. ex) switches, knobs, light, motion sensors ...

      • Actuators : components that convert electrical energy into other forms. ex) light bulbs, motors, LEDs, heaters ... 

      • Electronics : reading changes in electrical properties as information. 

      • Transduction : changing one energy into another.

      • Transducers : devices that changes one energy into another. 

      • Voltage : measure of the difference in electrical potential energy between two points in a circuit. -> measured in Volts

      • Current : measure of the magnitude of the flow of electrons through a particular point in a circuit. -> measured in Amperes, or Amps

      • Resistance : measure of a material’s ability to oppose the flow of electricity. -> measured in Ohms







      Understanding DC Power Supplies

      Abbreviations
      • V : Volts

      • A : Amperes

      • W : Watts

      • mA : miliAmperes

      • VA : Volt Amperes

      • VAC : Volts AC

      • VDC : Volts DC

      • DC : Direct Current

      • AC : Alternating Current






      Lab : Components

      Components
      -> https://itp.nyu.edu/physcomp/labs/components/









         Lab : Setting up a breadboard

         Setting up the Breadboard

         -> Figure 10. 
        Solderless breadboard with a 7805 voltage regulator mounted on it.

        Using a Breadboard with a Microcontroller

        -> Figure 15.
        Breadboard view of an Arduino Nano mounted on a solderless breadboard.


         Powering a breadboard circuit from a microcontroller via DC power supply

        -> Figure 16.
        Breadboard view of a Nano 33 IoT on a breadboard connected to a DC power jack for external DC powering. The jack’s positive terminal is connected to the Nano’s Vin pin (pin 15) and the negative terminal is connected to ground (pin 14). In this configuration, the Nano will run, and will output 3.3V between the 3V3 pin (pin 2) and ground.


        -> Figure 17.
        Breadboard view of a Nano 33 IoT and a 7805 voltage regulator powered from a DC power jack. The DC power jack is wired as shown in the previous figure (positive terminal to Vin, negative terminal to ground. However, in this image, a 5V regulator is added on the breadboard below the Nano. Its Vin pin is connected to the Vin of the Nano (and the DC power supply’s positive terminal) and its ground is connected to the ground bus. In this circuit, you can supply 3.3V via the Nano’s 3V3 pin (pin 2), 5V from the 7805 regulator, and 7-21V from the DC power supply.


         Powering the breadboard without a microcontroller
        -> Figure 21.
        Schematic image of a 220-ohm resistor and an LED connected to a 7805 5-volt regulator. Regulator pins are numbered from left to right.  One terminal of the resistor is connected to the regulator’s output pin (pin 3), and the other terminal is connected tothe LED’s anode. The LED’s cathode is attached to the regulator’s ground pin (pin 2). A 9-12V DC power source is connected to the regulator’s voltage in (pin 1) and ground (pin 2).


        Figure 25.


        Figure 29.







        Lab : Electronics and using a Multimeter

        The controls on a meter

        • Voltage : This setting is generally broken up into Volts DC, indicating that the polarity of the voltage will not change, and Volts AC, indicating that the polarity will alternate.

        • Amperage : This setting measures the current in a circuit. It’s usually broken up into AC and DC. There are commonly two holes for the positive probe to measure current, one that’s low amperage and the other that’s high amperage.

        • Resistance : Resistance is measured in ohms. This function is sometimes grouped with the continuity check.

        • Continuity : Continuity measures for a connection, generally very low or no resistance.

        • Diode Check : Diode check measures for a voltage drop across a diode, typically 2.7V or less. If you hold the positive probe on the anode of the diode and the common probe on the cathode, you’ll see a voltage drop. If you reverse the probes, you’ll see no reading.



        The symbols on a meter

        • Volts : V
        • Ohms (resistance) : Ω
        • Amps (current) : A
        • AC : ~, ⏦ (tilde, sine wave)
        • DC : ⎓
        • Continuity : diode, speaker
        • Diode Check : diode
        • Non-Contact Voltage : NCV
        • Ground : ⏚ (vertical line with three horizontal lines below it)



        Measuring voltage
        -> Figure 23. 
        220-ohm resistor and an LED powered by a regulator.





        A switched LED circuit



        Component in series



        Component in parallel



        Generating a variable voltage with a potentiometer









        Lab : Switches

        Switch terminology



        Project 1 : Three switches in parallel



         Project 2 : Three switches in series



         Project 3 : Switching a DC motor






        ->
        The motor worked, but it only rotated very slightly, likely due to insufficient power from using 5V. Next time, I think I’ll need to try a higher voltage.







        Questions

        • If I supply power to the breadboard using a 5V DC power jack and then pass it through a 5V regulator, would that result in no change? Or, even though it's still 5V, does passing through the regulator cause the output voltage to drop slightly?

        • I’m not entirely sure about the correct order of connecting the in/ground/out when operating the motor. 
          I wonder if the sequence varies depending on the motor or if the same order applies to all motors.
        • I want to understand how important resistors are when designing electrical circuits. Once, during a practice, I didn’t use a resistor, and the filament in the LED blew out under 5V. Should resistors always be used when designing circuits, or are there specific situations where they are necessary? I'm curious to know when it's appropriate to use them.

        • While following lab exercises, it seems most of them use a DC power jack to supply power. I'm wondering if it's acceptable to choose from different power supply methods based on personal preference during the labs.