Computer Input and Output

• Equipment used to secure components to an electronic circuit board: Soldering iron.

Inputs and Outputs

• Input devices send information to a computer.
• Output devices receive information from a computer.

How Computers Work

• Computers store and process information.
• Processing involves organizing and working with information, done by the CPU.
• Computers process information that is given to them (input).
• After processing, computers send the information back out (output).
• Computers work with information converted into a numerical code through digitisation.
• Digitised information is called digital data.
• Information from digital devices is already digitised; non-digital information needs digitisation via a scanner or camera.

Input Devices

• Input devices include keyboards, touch screens, microphones, movement sensors, and webcams.
• Examples of input: words from a keyboard, screen clicks from a touch screen, live video from a webcam, sound from a microphone, movement detected by a motion sensor.

Output Devices

• Output is sent to devices like screens, printers, speakers, headphones, lights, or motors.
• Examples of output: sound from a speaker, text on a screen, printed pictures, video on a tablet, movement from a motor.

Connecting Devices

• Some input devices are built-in, like screens.
• Others connect via cables to ports or wirelessly via Wi-Fi.
• Some devices, like tablet touch screens, function as both input and output devices.

What is a Circuit?

• Electricity is the flow of electrons.
• An electric circuit is a pathway for electricity, involving electronic components connected by wires.
• Circuit diagrams use symbols to represent electric components.

Ohm's Law and Resistance

• Resistance is the opposition to electrical current, affected by material, length, thickness, and temperature.
• Copper has lower resistance than steel.
• Longer wires have greater resistance.
• Smaller diameter wires have greater resistance.
• Heating a wire increases resistance.
• Current is increased by increasing voltage or decreasing resistance.
• Increasing voltage across a component increases current; too high a voltage can break the component.
• Adding lamps in a series circuit increases resistance and decreases current.
• A variable resistor can change resistance in a circuit.
• Ohm's Law: Voltage = Current × Resistance (V=IR).
• Resistance (R) is measured in ohms (Ω), voltage (V) in volts (V), and current (I) in amperes (A).
• Metals are good conductors because of free electrons; plastics are insulators due to lack of free electrons.
• Conductors have low resistance, while insulators have high resistance.
• Resistors restrict electron flow by converting electrical energy into heat, thus reducing current or voltage.

Resistors

• Resistors introduce controlled resistance into circuits.
• Resistor resistance is indicated by colored bands.
• The first two bands indicate the first two digits of the resistance value
• The third band is a decimal multiplier: number of powers of ten to multiply the first two numbers by

Transistors

• Transistors act as switches, commonly used in electronics.
• Two main types: NPN and PNP, with NPN being more common.
• Transistors have three leads: base (activates the transistor), collector (positive lead), and emitter (negative lead).
• A small current/voltage at the base of an NPN transistor allows a larger voltage to flow from the collector to the emitter.
• The resistor protects the transistor from high voltage or current.
• Essential in many circuits, sometimes used to amplify signals.

Ergonomics

• Ergonomics involves the study of people and their environment.
• Anthropometric data (body measurements) are applied to designs for comfort.
• Anthropometry measures physical aspects like height and width, collected and graphed for analysis.

Plastics

• Two types of plastics: thermoplastics and thermosetting plastics.
• Thermoplastics can be repeatedly heated and shaped because there are no links between the polymer chains.

Soldering Steps

• Start with the smallest components and work up to the taller ones, soldering any interconnecting wires last.
• Place the component correctly, ensuring it sits flush against the board, and bend the leads slightly to secure.
• Clean the warmed-up soldering iron tip with a damp sponge if needed.
• Place the soldering iron on the pad and feed the solder onto the pad.
• Remove the solder, then the soldering iron, and let the join cool for a few seconds.
• Trim excess component lead using cutters.
• To correct mistakes, heat the joint and use a solder extractor to remove molten solder.