Electricity vs Electronics

• Electronics is the science of studying and designing devices related to the behavior of electrons in matter and controlling the flow of electric current.
• Electricity and electronics both use electric current, but they differ in several ways

Voltages and Intensities:

• Electricity works with high voltages and intensities.
• Electronics operates with reduced voltages and intensities.
• Electricity uses large power, while electronics uses small power.

Components:

• Electricity uses high-power components like bulbs, motors, switches, and commutators.
• Electronics uses special electronic components to operate and control small currents and voltages in electronic circuits.
• Electronic components include capacitors, diodes, and transistors.
• Electric components are larger than electronic components.
• Electric components consume more energy than electronic components.

Applications:

• Electricity works with high power, used in applications requiring high power, like moving machines in factories, and lighting houses and cities.
• Electronics operates with reduced power, suitable for information technology applications like computing, telecommunications, sound, photography, and video.

Resistor Color Codes

• Color codes easily identify the theoretical value of a resistor, with four bands.
• Three bands give the theoretical resistance value, while the fourth provides the tolerance.
• The first band (1st stripe) corresponds to the first digit as a number.
• The second band (2nd stripe) corresponds to the second digit as a number.
• The third band (3rd stripe) acts as a multiplier factor, corresponding to the number of zeros to put after the first two digits.
• The fourth band (4th stripe) indicates the tolerance.
• The color codes include black, brown, red, orange, yellow, green, blue, violet, gray, white, gold, and silver.
• Each color represents a digit for the first and second bands, a multiplier factor for the third band, and a tolerance percentage for the fourth band.

Electronic Components

• Electronic components divide into two types: passive and active.
• Passive components only act as receivers and consumers of the electric signal, without generating any signal gain or control.
• Passive components include resistors, capacitors, and coils.
• Active components can generate, modify, or amplify the electric signal
• Active components examples: diodes and transistors.

Passive Components: Resistors

• The value of a resistance calculates using color codes.

Fixed Resistors:

• Fixed resistors always have the same ohmic value.
• Fixed Resistors applications in electronic circuits:
• Provide a known resistance to the passage of current.
• Limit the value of the current (protection of components against large currents).
• Control or fix voltages (polarize circuits).

Variable Resistors:

• Variable Resistors have the capacity to vary their ohmic value within limits.

Potentiometers:

• Variable resistors have resistance values which can be modified by moving a cursor or rotating an axis.
• Potentiometers modifies the resistance from 0 to the maximum value indicated on their body, also called rheostats.
• Variable resistors applications: regulators of intensity in applications of control of level of luminosity and sound.

Light Dependent Resistors (LDR)

• Light Dependent Resistors vary their resistance according to the amount of light affecting them
• LDR ohmic value increases in darkness and decreases as light increases.
• LDR are used as light sensors in applications like automatic light on/off, illumination detector for flashes in photo cameras, photoelectric cells, anti intrusion alarm systems, smoke detectors, etc.

Temperature Dependent Resistors (NTC and PTC):

• NTC resistors diminishes resistance when temperature increases.
• PTC resistors increase resistance when temperature increases.
  • NTC: increasing temperature decreases resistance
  • PTC: increasing temperature increases resistance
• Thermistors Applications: most common Thermistors are NTC, used as temperature sensors in thermostats, thermometers, protection circuits of electric devices against temperature and home automation, fire detectors, etc.

Capacitors

• A capacitor is an electronic component capable of storing electrical energy in the form of electric charge, which is then used to power devices.
• A capacitor consists of two metal plates separated by a dielectric (insulator).
• When capacitors acquire the maximum load, they impede the passage of current, acting like an open switch.
• The capacity of capacitors is measured to give an amount of charge that one is capable to store at a given voltage.

Submultiples of capacitance:

• Micro (µ) = 10^-6
• Nano (n) = 10^-9
• Pico (p) = 10^-12 q = charge V = voltage
• There are two types of capacitors: without polarity and with polarity.
• Capacitors with polarity usually have a greater capacity and have poles (positive and negative).
• When connecting them, polarity must be taken into account because otherwise they would be damaged.
• Capacitors, like any element, can be associated in series, in parallel, or in a mixed way, obtaining an equivalent capacity.
  • In series: 1/Ceq = 1/C1 + 1/C2 + ... + 1/Cn
  • In parallel: Ceq = C1 + C2 + ... + Cn

Time Constant of a Capacitor (τ)

• The time constant of a capacitor defines the time it takes to charge or discharge a capacitor completely
• τ (tau) calculates as 5-times (5*) the product of the capacitor's capacitance times the resistance through which the capacitor charges or discharges.
• τ = 5 * R * C
• Capacitors are components capable of storing electric charge, therefore behaving like "electric power storages".
• Capacitors act as temporal charge deposits to fulfil certain tasks, acting as timers and delays (also batteries, filters, communication circuits).

Relays

• A relay is an element that allows connecting two independent circuits.
• One of the circuit powers the relay with a small voltage.
• Relays are made with two different circuits: the activation circuit and the working circuit.
• The activation circuit is an electromagnet (coil) that works with low intensity current.
• The electromagnet attracts a metal piece (armature) when closing this circuit.
• The armature activate the other circuit when it moves.
• The work circuit is made with a set of contacts that move when actioned by the armature.
• It can have two, three or more contacts, relying on its application regarding the number of contacts on it.
• The two contact relays used as switches, the three as commutators.
• Operation is based on magnetism
• Current flows through the coil when pressing the button
• Coil current generates a magnetic field attracting a soft iron metal sheet.
  • Drawing the metal sheet to touch the contacts
  • If current stops through the coil, contacts separate.
• Relays are automatic switches or commutators electrically controlled, therefore being applicated on automation, control of electric actuators, and triggers of high power circuits.

Voltage Dividers

• Resistances are the simplest electronic components whose main function is double:
  • Limit the intensity of current flowing through a branch of the circuit with a desired value.
  • Induce a certain voltage drop between the extremes of one circuit to protect different elements.
• Voltage dividers are used to connect (provide feeding voltage) to a device, using a smaller voltage than an available batteries.
• A voltage divider consists of two resistances in a series, selecting the terminal extremes of one of them (A and B) to connect a new device.
  • VAB = Output Voltage
  • The output voltage is greater the greater the electric resistance that it is associated to.

Active Components and Semiconductors

• Semiconductors are materials with intermediate characteristics between conductive and insulating materials.
• Semiconductors operate as insulators in normal conditions
• Energy conducts them when giving external energy, such as high temperatures surpassing their own component level.
• Intrinsic semiconductors: silicon and germanium that occur in nature
• These elements are tetravalent, with four valence electrons forming covalent bonds in which they share electrons with their neighbors.
• Extrinsic Semiconductors: are intrinsic materials that have been doped (introducing impurities)
• This converts the semiconductor into a conductor with a lower energy supply
• There are two types: N and P.
  • Type N has excess electrons, creating negative charges.
  • Type P has default electrons, creating positive charges.

Semiconductor Diode

• Semiconductor diodes are active electronic component that allows electric current to travel in only one direction (the direction indicated by its own element's electricity symbol)
• This diode can connects N type semiconductor with a P type semiconductor.
• Electronic elements act as open or close switches which depends how incoming current arrives.
  • Acts as close switch and allow current when current comes directly (direct polarization).
  • Acts as open switch and doesn't allow current when current comes inversely (inverse polarization).
• There are two basic types of diodes: rectifying diodes and LED diodes.
• To recognize the anode from the cathode, diodes have a white ring attached to the cathode terminal (or negative terminal).
• Diodes are used as a rectifier to convert AC to DC in power supplies and as LED indicators/emitters/detectors in devices such as semiconductors, screens, and remote controls.

Transistors

• Transistors are semiconductor devices used as amplifiers or INTERRUPTERS controlled by a small current (base current).
• A transistor has 3 connection terminals: Base (B), Collector (C) and Emitter (E).
• Transistors act as switchers triggered by the incoming current through their base. The resistance between collector and emitter greatly reduces when certain current reaches the base.

Transistor as an Amplifier

• Transistors also amplify since high currents travel to the bulb after the resistance reduces.
• A small current through the Base permits electricity to flow, which functions as an amplifier to the Base's current.
• Transistors can also manipulate the Magnitude of high Collector currents by controlling the amount of small currents arriving to the Base.
• The intensity and value of the Collector's current also changes.
• In short, it permits electrical waves to be amplified or manipulated as needed.

Current gain (β or hFE):

• The relationship between the Base current and the Collector current is called current gain.
• A 100 gain transistor means it generates 100x the Collector current than the Base.
• Essentially for multiplying or controlling an electrical signal's strength
• Transistors are vital for circuit automatization like sensors.
• LDR or NTC sensors generally makes a poor signal to power a machine.
  • Signals are passed in weak and made stronger to be effective.