Digital Electronics

Digital ElectronicsReview of Basic Electronics

Electronics:• Examples: Computer, iPod, Calculator, Solar

Panels, Hear monitors

• Something that runs on electricity

• Allows human to communicate with machine

• Regulate control over electricity to be utilized the way people want them to be.

Electricity:• Flow of electrons through a conductor

• Current that produces power

• Electronics -> Atoms -> Valence electrons• Negative Charge: too many electrons

• More electrons than protons

• Neutral: even # of electrons• Positive Charge: doesn’t have enough electrons

Every Wants To Be Balanced

• Cups of H20

• If Full Empty

• But if add a tube… What happens?

• Equals Out …How?• Everything is Lazy -> Gravity Needs to Push to

make water move• Electricity’s push is - - voltage

3 Major Players in Electricity• Voltage: Electrical Pressure

• Measured in Volts• V

• Current: The flow of electrons• Measured in Amps• A

• Resistance: The opposition to the flow of electrons

• Measured in ohms• Ω

• Water & Electricity act very similar

Faucets…

Back to Water in the Faucet…• Why is the water not flowing?

• We understand there is pressure in it but it’s not flowing ..why?

• To much Resistance- Resistance is HIGH

• As resistance increases current flow decreases• -> They are inversely proportionate to each other

(if the resistance is high the current is low, if the resistance is low current is high)

So What Did We Learn?• Pressure has to be present

• Without pressure can’t have current flow

• Without current can’t have resistance

Basic Circuit

• Potential Difference: have inequality

• Basic Parts of a Circuit:• Power Source – Acts like a pump

• Ex: Battery, transformers (steps down, up electricity)

• Conducting Path • Ex: Wires

• Load• Ex: neg/pos lightbulbs, heaters, resistors,

photo resistors

− +

Conducting Path• Conductor – anything that allows electricity to

flow freely (usually good conductor of heat)• Usually metals (1 electron)• Best Conductor: Gold• 2nd Conductor: Copper

• Insulators – any material that does not allow electrons flow through freely (balanced electrons)

• Semi-Conductor: which will allow electricity flow under certain conditions

* We build a circuit to make it do work• When we plug in a battery charger it needs to be greater than the battery –this

will reset potential difference• Ex: 9v needs a 12v

− +

Encounter resistance in the wire (filament is made of tungsten, a certain steel)

Filament has a small hole -> electricity is stuck & creates heat -> which in turn gives off light

Flow will be slower

Very Slowly it will begin to fill up.When reaches a balance it’s dead

Power Source• Electricity comes in 2 flavors…AC/DC

• AC -> Alternating Current, changing• DC -> Direct Current

• DC-> All batteries are DC• Anything DC has polarity +,-

• DC current travels in a linear fashion• Definite start –• Definite end +

Power Source

• Every battery has - +

• AAA, AA, D, C = 1.5v

- +- + - +- +

-

+-

+

-

+-

+

1.5v 1.5v 1.5v 1.5v

3v

1.5v

Double Amps (like jumping a car)

Pressure is the same but the flow is powerful (ex: like a Y connector for a hose)

Conducting Path• Wires: always made up of conductors &

insulators• Copper, Aluminum and Silver are used

• Stranded: like braided rope – a hole bunch of strands put together to create one• Much more flexible• Easier to Handle• Less Likely to develop an open break

(higher gage # smaller the number)

Conducting Path• Solid Core: less resistance

• In a house, like Romex

• Printed Wiring: • Printed-Circuit (PC) or printed wiring (PW)• On one side -> components on the other conducting

paths printed with silver or copper on the board –instead of using wires

• Grounding Wire: • Connects the electrical system to the earth• Allows excess electrical power to find

it’s way to the earth

Switches• Switches: controls electrical current passing

through a circuit• Always wired so that it is controlling the hot (black

or red) wire. If a switch is wired wrong it will create a dangerous condition.

• Controls whether the current is ON or OFF• Closed Switch: Practically zero resistance• Open Switch: Nearly infinite resistance

• Types: Toggle, Push-button, Rocker, Slide, Rotary, and DIP

http://www.allaboutcircuits.com/vol_1/chpt_1/5.html

Switches• SPST: Single Pole Single Throw

• SPDT: Single Pole Double Throw

• DPST: Double Pole Single Throw• Controls 2 completely separate circuits

simultaneously

• DPDT: Double Pole Double Throw

• Pole: the # of completely isolated circuits that can be controlled by the switch

• Throw: the # of closed contact positions that exist per pole

(Dashed line: indicates both sets of contacts within the switch are opened and closed simultaneously)

Switches• Push button Switches:

• Often spring loaded• Either normally open (NO)

or• Normally Closed (NC)

• DIP (dual-inline package) Switch:• Consists of 8 miniature rocker switches

• Each switch can be separated

Circuits• Circuits: the basic circuit with just a battery $

light bulb is unpractical there needs to be a control = switch

• Open Circuit: when any part of the path is open or broken. Result –no current

• Short Circuit: closed path but resistance is practically zero. Result – to much current

(too much current in the wires but no current through the bulb)

• Closed Circuit: creates electricity (basic circuit)

Closed Circuits Review…• There must be a source of potential difference.

Without the applied voltage, current cannot flow

• There must be complete path for current to flow, from one side of the applied voltage source, through the external circuit, and returning to the other side of the voltage source.

• The current path normally has resistance. The resistance is in the circuit for the purpose of either getting heat or limiting the amount of current.

Load• Resistors

• Wide range of R value• From a fraction of an ohm to many kilohms (kΩ)

and megohms (MΩ)• Too much heat can make the resistors burn• Carbon resistors-common type have color coded to

differentiate from one another because so small

• Band A -> First digit• Band B -> Second digit• Band C -> Decimal Multiplier• Band D -> Tolerance

Resistors

• No Band = +- 20%

5-Band Code• Purpose: to obtain more precise values.

• First three colors indicate first three digits• Followed by decimal multiplier in the fourth stripe• Tolerance is in the fifth strip

• Brown: -+ 1%

• Red: -+ 2%

• Green: -+ 0.5%

• Blue: -+ 0.25%

• Violet: -+ 0.1%

Power of 10 Multipliers…• Giga – G – 109 – 1,000,000,000

• Mega – M - 106 – 1,000,000

• Kilo – K or k - 103 – 1,000

• Milli – m – 10-3 – .001

• Micro – ☐ - 10-6 – .000,001

• nano – n – 10-9 – .000,000,001

• pico – p – 10-12 – .000,000,000,001

Circuits: SeriesSeries circuit: a circuit in which the current has only one path. In a series circuit, all of the current passes through each of the components in the circuit.

Circuits: Series

• To Calculate total resistance of a series circuit use the following formula..

• RT = R1+R2 +R3

RT = 2.5 + 1 + 3RT = 6.5 kW

Circuits: Parallel

Circuit: Parallel

• RT = 1 ÷ (1/R1 + 1/R2 + 1/R3 . . .)

RT = 1 ÷ (1/1 + 1/2.5 + 1/3)RT = 1 ÷ (1 + 0.4 + 0.33)RT = 1 ÷ 1.73RT = 0.58 kW

Circuit: Compound• Compound Circuit: a circuit that contains both

a series circuit and a parallel circuit

RT = 1 ÷ (1/2 + 1/4)RT = 1 ÷ (0.50 + 0.25)RT = 1 ÷ 0.75RT = 1.33 kW

RT = 1.33 + 3RT = 4.33 kW

Ohm’s Law• If we keep the same resistance in a circuit but

vary the voltage, the current will vary.

• I = Current V = Voltage R = Resistance

• High Voltage But Low Current• With high voltage, the current can have a low value

when there is a very high resistance in the circuit

• Low Voltage But High Current• Low voltage in a very low resistance circuit can

produce a very high current

Ohm’s Law• I = V/R Amperes = volts/ohms

• V=IR

• R=V/I

Electric Power• Power in Watts = Volts X Amperes

• P = V X I

• Power = work / time

• Work = power X time

Components

• http://www.technologystudent.com/elec_flsh/button1.html

• LED and typical circuit schematic

Capacitors• A capacitor which is an energy-storage device is

used to store energy

• There are various types of capacitors:• For Bypassing High Frequency to

the Ground • Ceramic Capacitor: looks like a disk shape.

It is used to bypass high frequency to the

ground.• Multilayer Ceramic Capacitor

Capacitors cont…• For large value capacitance

• Aluminum: It consists of two electrodes. One being a negative and the other a positive one. It has polarity. Largely, these electrodes are made of aluminum. The capacity of an electrolytic capacitor is measured on the scale of µf. The minimum capacity can be µf. While the maximum can lead to near 1000µf.

• Other types…• Tantalum • Super Capacitor

• Non polarized:• Mica Capacitors• Polystyrene Film Capacitors

Capacitor• Store energy for a circuit.

• Look 2 ways:

• Measured in farads, ex: 47uf • uf means micro farad

• Two wires :• same size = letting you know it doesn’t matter

which way it goes in to a circuit• Different size = short wire is the negative side of the

capacitor.• Recommended amount of volts show on

cylinder capacitors

cylinderdisc

Diodes• A diode is a "one way valve" for electricity.

• It is a semiconductor composed of silicon or geranium, containing a PN junction.

• The end of the diode that is an arrow is called the anode (P-type crystal), and the line end is called the cathode (N-type crystal).

Some info on Diodes..• If the positive terminal of a battery is connected to the

anode, and the cathode is connected to the negative terminal, the diode is forward biased, and the current can flow through it.

• If the diode is reversed, and the cathode is connected to the positive terminal, and the anode is connected to the negative terminal, the diode is reverse biased, and very little current flows.

• Note that when the diode is forward biased, it is pointing + to -. For this reason it is easier to think in terms of conventional flow (+ to -), rather than electron flow (- to +).

Diodes• 1. Cathode (side with the stripe)

• 2. Anode (side without the stripe)

• 3. Anytime the cathode is more positive than the anode, no current will flow.

LED’s : Light Emitting Diodes• Tiny light bulbs that are many different colors

and have one short leg and one long leg. The short leg is the negative and the long leg is the positive.

• Photo cell:• Used for a sensor. • It detects light and if used right can light up your

LED if something interferes with the light.

(ex: night light)

Voltage Regulator• A device or circuit

designed to maintain

a voltage or current at a

Predetermined value.

IC chip• Use: the brain of a small circuit or pretty much

any circuit.

• Has a ton of little legs and each leg does a specific job.

• Different chips are used for different results and some chips are very easy to blow.

(see packets given)

Transformer• Changes high ac voltage to a lower or higher

value.

Transistors• Looks like a half a moon with three legs.

• Usually grey or black.

• The 3 legs represent an important role:

• The mark on the top, like a notch or small circle. From that notch work your way in the opposite direction with the first leg being the emitter, the second leg or middle leg is known as the base and the last leg is the collector.

• Use: Amplify current as well as act like a

switch in the circuit

FETS

Works Cited• Webiology of Electronics• http://images.google.com/imgres?imgurl=http://www.geocities.com/mistertippy/components/DiodePic.jpg&imgrefurl=http://www.geocities.com/mistertippy/

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