BCST 1101 Electricity

What is Electricity?

  • Electricity is a bunch of physical elements that come from the flow of electrically charged particles

    • matter is made from atoms

    • atoms are made from particles

Atom with Charged Particles

  • Electrons

  • Protons

  • Neutrons

Electricity

  • Provides power

  • makes video and audio

  • transmits data

  • can be static

  • can be in motion

    • electric charges in motion create current

    • current is what we normally think of as electricity

Static

  • static means not moving

  • so static electricity is an accumulation of charges that stay put

  • static charges are used inside many microphones

Doing all the work

  • electric charges in motion do most of the work we need

  • power, data, audio, video, lights

Atoms and their Charges

  • atoms have particles with positive, negative and neutral charges

  • Protons have a positive charge

  • Electrons have a negative charge

  • Neutrons have a no charge (neutral)

What is a Charge?

  • it is basic property of matter that governs how the atomic particles are affected by an electric or magnetic field

Three Possible Charges

  • electrons have a negative charge

  • protons have a positive charge

  • neutrons have no charge

Three Possible Actions

  • opposite charges attract

  • Like charges repel

  • neutral charges do nothing

CHARGE!

  • electrons have been removed from the person and their hair by touching the silver ball by a Van Der Graaf generator

  • A machine that attracts electrons

REPEL!

  • The person now has a net positive charge

  • Including the hair

  • With the same charge they they are trying to get away from each other (and the head)

For the purpose of the course, we will refer to electrons as

  • being round

  • having a minus sign showing their charge

  • travelling in one direction in groups or alone

Handy things about Electrons

Electrons Move Easily

  • Electrons can be made to move much more easily away from protons and neutrons

  • so electricity form the basis of electricity

  • otherwise we might have called it prolixity or neutricty

They Use the Force

  • Electrons generate a force field around themselves

  • An electric field also knows as an electromagnetic field or an EM field

Magnets in Space?

  • when moving, the force field becomes a magnet

  • With a north and South Pole and everything else a magnet can do

How do electrons move?

  • certain atoms can gain or lose and electron when influenced by an outside force

  • like another electron

Ion

  • this “unbalanced atom” is known as an ion.

  • The ionizing of the atom causes the charge to transfer to an adjacent atom

Ions lead the charge

  • If that transfer happens only once, ie an electron leaves an atom but another one doesn’t relaplace it, that creates a “charge” - aka static electricity

  • If the transfer continues in a cascade

  • With one or more electrons bouncing from atom to atom, we call that cascade a “current”

Electric Fields

  • electrical charges alter the nature of space around them

  • as we said, electrons create a field

  • they have charges

Electromagnetic?

  • When in motion these fields are “electro-magnetic” or EM

  • EM fields have a magnetic polarity - what we call north and south

Electromagnetic Fields

  • EM fields also have an ionic polarity

  • What we call positive and negative

  • Therefore EM fields are polarized and energized

  • Polarized as in directional

  • Energized as in can propel matter away or towards

  • Attract or Repel

  • EM fields are temporary. They only exist as long as the electrons are creating current

  • Once the motion of the electrons stop the magnetic field collapses

SideBar: EM vs Magnets

  • Electromagnetism is different from magnetism in that magnets are not electrical

SideBar : Magnets

  • Electromagnetism is different from magnetism in that magnetic materials re permanently magnetic

  • EM loses its magnetism as soon as the current stops

Magnetism is a Non-contact force

  • which means that magnets can also apply a force without having to touch or contact the object or objects being affected

  • This relates to us how?

    • non contact forces are the basis for:

      • radio/RF

      • induction

      • electrical interference

Physics Facts

  • everything wants to be neutral

  • meaning that objects want to return to a low energy state from a high energy state

  • objects will move to a neutral state (if they can)

  • charges will keep moving until they find a balanced state (no charge)

  • when protons equal electrons in an atom

There are some basic things needed to make electricity move

  • Power Source: an excess of electrons

  • Conductor: A material with plenty of moveable electrons

  • Complete Circuit: A path from negative back to neutral/postive

Electric Current is Counting Electrons

  • electric current is the rate of flow of charge through a conductor

  • unit of electric current: the ampere, A

  • 1 ampere is approx. 6.2415093×10^18 electrons per second or 6,241,509,300,000,000,000 (quintillion) passing by a single point

Sources differ in the way current travels

  • AC

    • alternating current

    • made by rotating a magnet inside a coil of wire

    • or by rotating a coil o wire around a magnet

  • DC

    • direct current

    • made by batteries

    • or by lightning

Electric Current is things not a force

  • few electrons, low current flow

  • many electrons, high current flow

Voltage is what makes electrons go

  • voltage is the “pressure” that makes electrons go

  • more pressure, more electrons move past = high current flow

AC and DC current states

DC Current: constant number or electrons travelling in the same direction

AC Current: changing number of electrons traveling in two directions - ahead and back

A Brief Summary

  • electrons carry negative charges

  • electrons move towards positive charges

  • positive charges re not made of positive particles

    • rather they result from the net loss of negative charges (electrons)

  • When electrons move away from an object, or from molecules, a deficit(lack) of electrons remains

  • the last means the object/ molecule now has a positive charge.(is less negative)

  • a gathering of stationary electrons is a “charge”

    • like static electricity

  • If electrons arrive to replace the missing, then you have a travelling “train” of electrons which creates “current”

  • electricity is a non contact force

    • it can affect materials that it doesn’t touch

    • it can also affect materials it touches.

  • Electrons need;

    • conductors to travel along

    • a power source that generates electron motion

    • a return route to the positive to be able to balance the charges

      • this route is known as a circuit

  • The Ampere is the unit of electric current

    • current is charges in motion

    • therefore current is electrons in motion

  • The volt is a unit of force - the pressure that drives the electrons. The thing that makes them move.

Power Sources

p= energy transformed/time = QV/t

What is Power Again?

  • Power is the energy transformed by a device per unit of time

  • the unit of power is the watt the sign for Watt is W

Power Sources

  • power sources are just things that cause an imbalance of electrons, or e=casue electrons to start moving from atom to atom

  • Examples of Power Sources

    • static electricity

    • batteries

    • generators

Batteries

  • Batteries are designed so that the chemical reaction can occur only when electrons move through the external part of the circuit

  • electrons don’t move until the battery is hooked up

  • Batteries are Chemical Soup

    • batteries convert chemical energy directly to electrical energy

    • for instance, energy can be stored in Zinc of Lithium, which are high-energy metals

  • Basic Battery Construction

    • a medium that will supply electrons inside the battery

      • the electrolyte

    • An electron “emitter” at one end to let the electrons out

      • the anode

    • An electron “collector” at the other end to return electrons and completes the circuit

      • the cathode

  • Basic Battery Operation

    • connect the two ends with a conductor

    • Voila! Current flows

      • that would be a short circuit so add a LED or something

  • Basic battery Types

    • If the battery is made of liquid, its called a “wet” cell battery

    • If not, then it’s a “dry” cell battery

Dry Cell Batteries C and AA style

  • Lithium Dry Cell Batteries

    • same idea as C and AA but that cathode and anode materials are pressed between separate sheets to make more surface area for electrons to travel along

  • Several Cells Connected Together Make a Battery

    • Although we refer to a single cell as a battery as well

  • More Cells make bigger battery

    • several cells together is how camera batteries and car batteries are made

    • having more cells means more electrons and so more voltage and/ or current are available

Power Sources: Generators

  • Generators- Alternator

    • alternators are generators that create alternating current

    • alternators also are rotating devices that use magnetic fields ro cause electrons to move

    • the current changes direction twice each rotation

  • Alternator- AC Current

    • Used for domestic and Industrial power supply (AC)

    • Common in the entertainment industry

  • Principles

    • in the electric generator the coil (the rotor) is turned, by a mechanical force

    • in the magnetic field

    • current is generated

AC Power

  • AC power is usually generated at distant power stations

Alternating Current Frequency

  • in North America, the power generators turn 60 rotations per second

  • 1 cycle/ second is called 1 Hertz. Hertz is a measurement of frequency. Therefore the electrical frequency of AC power in North America is 60 hertz

  • That will be an important number for video

Electricity Part 2: Current and Circuits

Electric Current

  • for DC current flow, there must be a path from one battery terminal, through the circuit and back to the other battery terminal

  • The same is true for AX current flow, except the path is from the feed (live) wire to the return (neutral) wire.

  • a complete circuit is one where current can flow all the way around

Current Flow

  • by convention, current is defined as flowing from high potential energy to low or even zero potential energy

Electron Current Flow

  • Since, electrons are negatively charges, they flow towards positive or area of free electrons

  • which is from - to +

  • or the opposite direction

Series and Parallel Circuits

Circuits in Series

  • series circuits are comparable a water pipe with several valves in a row

  • If you first close one valve a little, the flow goes down. And the pressure drops

  • Close down the second valve in a series, the flow goes down even more, more pressure drop

  • The flow/ pressure continues to drop all along the way.

  • no matter how much the pressure drop, all the water still passes all the valves on the way through

Common Things Wired in Series

  • light switches: simplest way to cut power

  • Circuit breakers: for safety

  • Batteries: because you want to increase voltage

  • Christmas lights: to save wire

So in Series Circuits…

  • pressure drops with more loads

  • voltage drops

  • overall quantity of electrons stay the same regardless of loads, so

  • current is constant

Parallel Circuits

  • its more common to connect equipment and apparatus in parallel

  • even here wee can compare with water pipes; connect two water pipes from one pump, in parallel

  • open one valve, and 100 percent of the water comes out at full pressure

  • open both valves and the flow is 50 percept volume but full pressure

  • In parallel circuits NOT all the water goes to all the valves but pressure remains the same

Common Things Wired in Parallel

  • Your house: constant voltage for all devices

  • Most commercial electrical systems

  • The exceptions are dedicated circuits where only one device is on the circuit. like a clothes dryer

So in Parallel Circuits

  • pressure remains constant

  • voltage remains constant regardless of loads

  • overall quantity of electrons is shared with each device so

  • current drops

Measuring Current, Amps, Volts and Ohms

  • current (amps) is measured in series

  • voltage and resistance (ohms) are measured in parallel

Electrical Loads, Resistance, Conductors and Insulators

Loads

  • You need a circuit first

    • to get electrons to flow so that they can do work, you need a circuit

  • The load is the strain that the energy is put under

  • Any divide that convert electricity into another form is considered a load

  • load is measured by how much effort required or resistance offered

  • so a simple resistor can be a load but so can an electric pump

  • and a light can be a load

A loaded circuit

  • if we want to turn the electron flow into something useful there must also be a load in the circuit. The load is what makes electrons do the “work”

Resistance = Heat

  • when the electrons flow in resistance material, they will collide with each other, ions and atoms

  • these collisions cause the generation of head as a by product

  • The collisions are the basis for resistance: Ohms

Resistance = Load

  • resistance is a load since it converts electricity into heat

  • This reduced the amount of electricity in a circuit

Resistance and Mass

  • More mass of conductor will allow for more efficient electron travel

  • a thicker wire will carry more current than a thinner wire

  • there will be less electrical flow in a thin conductor than in a wide conductor due to more electrons colliding causing friction and therefore heat

  • this friction increases the resistance and lowers the power output of the conductor

Loads and Work

  • loads are really work

  • and the unit for work is watt

Conductors

  • they are materials with electrons that are relatively free to move around

Insulators

  • Insulating from electricity

Insulators and Electrons Flow

  • insulators don’t conduct current at all

  • insulating materials can be used to protect us from getting hurt by the current in the conductors

Insulators are Not Shields!

  • Shields are Conductors designed to stray RF energy away from signal wires or to protect sensitive circuits from electrical interference

  • Insulators are non conductive materials designed to prevent the travel of electrons

Electricity Part 3: Induction, EMF and Radio Frequencies

Induction

  • from the word Induce

  • Definition: to lead or move, as to a course of action, by influence or persuasion

  • The key is influence, not direct contact

  • induction is a way of making electrons move without having to make contact with them

  • induction is how most electric power is made

  • induction is how Many microphones work

  • Induction is the key force behind:

    • power generation

    • transformers

    • radio broadcasting

what causes induction?

  • when you move a conductor in a magnetic field, an electric field is created in the conductor

  • this is the Electro Motive Force - EMF

Induction and EMF

  • the amount of EMF depends on:

    • the amount of the conductor in the magnetic field

    • how fast the conductor is moving in the field or how fast the field is moving around the conductor

    • the strength of the magnetic field

Specific Uses for Induction

  • radio

  • traffic light sensors

  • electric generators

  • induction cooking

  • wireless charging

  • transformers

Induction as Interference

  • with DC power or singles the EM field doesn’t move and so can’t create interference

  • AC power has moving EM fields that can be a source of interference

Electromagnetism is everywhere which can be a problem

  • electric fields close to a conductor can affect electrons in that conductor

EMF creates “Pressure”

  • induced voltage in that other circuit adds to the signals there

What could be affected by interference?

  • Low voltage analog signals generally, but digitals can be affected too:

    • Lav mic

    • XLR cables

    • BMC analog cables

    • USB cables

Sources of Interference

  • high powered devices usually

  • AC power cords and bistro boxes

  • Microwave ovens

  • electric motors

  • radio devices

How to fix it?

  • move the source

  • turn the source off

  • if power cables must cross signal wires, do it at right angles

  • use a shield

Radio

Radio is Induction

  • induced current makes a signal in a metal antenna

  • radio is just EMF in the “air”

Sources of RF Interference are

  • poor quality or Faulty LED lights

  • walkie talkies

  • microwave ovens

  • wi-fi

  • cellular phones

  • electric motors - hair dryers, blender, etc

  • generators

  • cars

  • electric busses

Ohms Law and Power Calculations

Ohms Law

  • ohms law describes the relationships between various aspects of electrical force

Ohms Law and Voltage

  • ohms law states the the current flowing in a circuit is directly proportional to the voltage

Ohms Law and Resistance

  • ohms law states that the current flow is also inversely proportional to the resistance in the circuit

Ohms Law and Math

  • ohms law consists of a number of ways to define relationships between work, current, voltage and load

  • the ohms law triangle: V/I*R

  • V= I x R

  • I = V/R

  • R= V/ I

The Power Triangle

  • This is the law we will be obeying as filmmakers

Ohms Law and Power

  • ohms law also describes the relationship between the pressure of current flow, the amount go electrons and the work being done

What is Power?

  • electrical power (P) in a circuit is

    • the rate at which energy is absorbed or produced within a circuit

  • a source of energy such a voltage will produce os deliver power while the connected load absorbs it

  • power is further defined as the amount of energy transferred or converted per unit of time

  • Watt is Power

    • watts for example are 1 joule of energy per second

How do we use Power?

  • light bulb and heaters absorb electrical power and convert it into either heat, or light or both

Power Triangle and Ohms Law

  • if you exchange Resistance for Power you get the power triangle

  • P = I x R

  • I = P/ V

  • V= P/ I

  • Power Triangle in Practical Terms

    • the unit for Power is Watts

    • The unit for Current is Amps

    • The unit for Volts is Volts

Steps to finding answers

  1. Determine : Determine wattages

  2. Add: Add wattages together

  3. Calculate: Calculate overall load

  4. Check : Check safety margin (20% is a good rule of thumb)

Cables and Connectors

Cables and Connectors

  • Remember that a wire is a single conductor

    • sometimes insulated, sometimes not

  • A cable is multiple conductors either twisted together os inside a common insulating layer

  • Cables often have a mechanism at either end to connect equipment or other cables, these are connectors

  • Connectors are on all kinds of cables including power, audio video, digital and network

    • not all cables have connectors

    • some are bare wire

    • some have lugs

  • Connectors come in 2 styles

    • Cable mounted

    • panel or chasis mounted

Cable types

  • coaxial with a conductor in the centre and the other conductor surrounding it

  • twisted pair

    • single insulated wires twisted into a + and - pair or pairs

    • the wires are twisted to help reduce interference

    • by twisting the wires together they share the interference load

    • otherwise there is the potential for one wire to have more interference than the other

    • its not a replacement for the shielding

    • but it does reduce interference

  • braided

  • solid core

Wire

  • Solid

    • like it says, a single strand of solid metal

    • cheap

    • rigid

    • good for large current applications

  • Stranded

    • multiple strands thin gauge wire

    • flexible

    • can be used for large current operations

    • also used in small sizes in headphones, etc

  • Braided

    • much less likely to break than a solid or stranded wire

    • can bend for more easily

    • used for shielding

  • Insulated or Non Insulated

Insulation, what’s it for?

  • Safety : keeps the electricity from escaping

  • Durability: Keeps other detrimental elements like moisture out of the wiring

  • Insulating the wire protects the internal metal from wear and prolongs the wire’s lifespan

Use your Gauges

  • remember, the longer the wire, the more resistance the electricity flowing through that wire will experience

  • use gauge to defeat that

  • gauge adds metal which adds electrons which reduces resistance

Connector gender “rules”

  • Plug: the male end

  • jack or socket: the female end

  • connector: the mechanism at either end

  • Most connector have the signal source come from the “male” connector

    • why? long standing conventions

    • power is the only exception to this rule

  • For power connections remember source - side - socket

    • why? because female connectors supply the power sources and are the socket

    • this is the reverse of most other connections

    • why? safety female connectors are hidden

    • male connectors would exposed and unsafe

The Most “Popular” Connectors

  • Phone Jack or TRS or Âź inch or 6.5 mm jack

    • Âź inch diameter connector originally used for plugging in telephone connections send the name phone plug/ jack

    • 6.5mm is the same size only expressed in metric

    • there are many variants of this style

  • TS? TRS? TRRS?

    • TS: Tip Sleeve

      • one audio channel aka mono

    • TRS: Tip Ring Sleeve

      • one audio channel and shield aka mono shielded

      • or two audio channels and no shield aka mono shielded

    • TRRS: Tip Ring Ring Sleeve

      • three audio channels. Stereo output and microphone input

      • no shield, common on phones

  • Mono phone jack

    • Âź inch (6.5mm) diameter

    • almost never referred to as TS

    • only two connector segments on the jack

      • hot (+)

      • return (-)

    • Mono phones jacks are still used for some microphones and musical instruments such as electric guitars

  • Stereo (headphone) jack

    • Âź inch (6.5mm) diameter connector

    • Three connector segments on the jack

      • hot (+)

      • hot right (+)

      • common (shared) return (-)

    • Common on stereo headphones

    • headphone cables are not shielded

      • they cannot replace TRS cables

  • Mini Phone aka 3.5(mm) mini

    • a 1/8 inch diameter version of the phone jack developed for applications with severe space restrictions

    • commonly used on headset potables and for audio connections to some computers and headphone jacks on some TVs

    • both mono and stereo versions exists

  • XLR

    • XLR only describes the style of the connector such as the shell design and the locking tab

    • There may be anywhere from 2 to 7 pins in XLR connectors depending on the applications

  • XLR or Cannon

    • XLR

      • a very robust, locking connector widely used in professional audio

      • Remember: not always 3 pins!

      • XLR mic cables are 3 pin but other XLR cables may not be

      • In analog applications, particularly in some high end consumer audio equipment, XLR connectors are used with balanced likes for optimal interference rejection

      • The pins in an XLR connector usually “point” in the direction of signal flow

  • 3 pin XLR

    • Sometimes called just “mic cable”

    • because most pro pics have 3 pin XLR connectors

  • 4 pin XLR

    • can be used with intercom systems

    • Some Dc power supplies have 4 pin XLR cables and jacks

  • 5 pin XLR

    • can be used with intercom systems

    • or DMX lighting systems

  • BNC

    • a very secure bayonet-style locking connector used in broadcasting gear for both video and radio signals. it is also common on professional test equipment

    • in consumer audio/video BNC connectors are mostly used in high-def set top receivers and high end video monitors, often as RGB or components video inputs

  • BMC Female

    • signal goes down the centre connector

    • note the centre socket

    • the “sexes” the connector

  • HDMI

    • high definition multimedia interface

    • Digital AV (audio video) cable

    • HDMI sizes and standards vary

      • sizes

        • standard

        • mini

        • micro

      • evolving standards

        • 1.2,1.3,1.4,2.0,2.1

    • Some features of the HDMI 1.4 Standard

      • HDMI Ethernet Channel- network data on HDMI

      • 3D TV: which tanked

      • 4K Support: enables video resolutions and colour spaces beyond 1080p

      • Content Type: Real Time signalling of content types

      • Control of Digital Rights Management

      • Automotive

    • Some features of the HDMI 2.1 Standard

      • All of the earlier standards plus

      • 60 billion colours, compare with 16 million

      • 8K support up to 60fps 10K for some industrial uses- digital signage for example

      • HDR

      • Variable refresh rate for gaming applications

      • 48 Gigs per second data rates

  • IEC AC Cord

    • normally referred to as a “standard power cord” or “universal power cord”

    • not really standard or universal

  • Hubbell plugs

    • high grade AC power

    • Also known as Hospital grade plugs

    • Edison plugs

  • USB Universal Serial Bus

    • USB allows computer peripherals, including A/V gear to be added in daisy-chain fashion

    • USB also delivers 5V DC power along with data

    • Type dictates Data speed

      • USB 1: 1.5 Mbits per second

      • UBS 1.1: 12Mbits

      • USB 2.0: 480 Mbits

      • USB 3.0: 5 Gbits

      • USB 3.1: 10 Gbits

      • USB 3.2: 20Gbits

  • RCA

    • a very common analog audio connector. Used for every sort os analog input and output, these come in colour coded pairs

    • “Coaxial” means the signal carrier and its shield are aligned along the same axis(generally a signal wire runs down the middle of a cylindrical shield)

    • first used to connect early electronic record players to radios and still sometimes called”phono jacks”

Other Connectors

  • F connector

    • f-type: the cable TV and FM antenna connector, used in conjunction with 75 ohm coaxial cable

    • cheap, simple to install, and relatively secure

  • Firewire (IEEE1394)

    • IEEE:Institute of Electrical and Electronics Engineers

    • Originally 400 Megabits per second digital data transfer, now 800, 1600 and 3200.

    • Used in streaming video, digital camcorder outputs, hard drive interfaces

    • essentially obsolete

  • RJ-11 (Telephone jack)

    • the commune modular telephone jack. universal on phones. modems, faxes and th elike

    • registered jack

  • RJ-45 (LAN cable)

    • same idea as RJ11 only more pins

    • also known as an ethernet connector

    • or category -5/ category -6

  • RJ trivia

    • both RJ-11 and RJ 45 are twisted pair cables

    • RJ 11 is 2 pais

    • RJ 45 is 4 pairs

  • Banana Plug

    • banana plug: a slender, slightly bulged metal prong that is attached to the stripped end of a speaker cable by a set screw in a plastic or metal sleeve

  • Binding post

    • it consists of a threaded shaft with a knob that can be tightened to secure either a spade lug or a loop of bare wire at the end of a cable.

  • Spade (Lug)

    • a common speaker connector

    • available with both solder and solder less connections

    • there are non solder “crimp” style lugs

    • crimp connectors are attached using a special tool to squeeze the connector unto the wire

  • Spring clip

    • a common speaker and antenna connector

  • Video RCA

    • physically and electrically identical to audio RCA connectors

    • Analog

    • tend to be yellow for easy identification

Adapter and Extensions

Adapters

  • adapters make it possible to connect different types of connectors together easily

  • adapter generally rugged and do not normally fail in use

  • you can choose which adapters you need by examining the two types of connect you are trying to connect together

Dongle

  • adapters that are on a short cable are often called dongles

Box or cable? Both!

  • adapters aren’t only cables

  • they can be devices like the DSLE audio adapter box shown here

Extensions

  • to make cable runs longer

  • a cable that always has the same type of connector on each end although usually the opposite gender

  • if the connections are the different type its an adapter cable