Unit 4- Building from Unit 4- Building from Schematics--Schematics--ContinuedContinued

EET 110 Electronics Survey IEET 110 Electronics Survey I

Topics to CoverTopics to Cover

Ohm’s Law as applied to Parallel Ohm’s Law as applied to Parallel CircuitsCircuits

Review Types of representationsReview Types of representations Wiring from schematicsWiring from schematics

Ohm’s Law Ohm’s Law RelationshipsRelationshipsVoltage (E) Amperes (I) Resistance (R)Voltage (E) Amperes (I) Resistance (R)

E= I X R

I= E/R

R= E/I

E

I R

Relationships in Relationships in Parallel CircuitsParallel Circuits

Parallel Circuit has multiple paths Parallel Circuit has multiple paths for electron flow through devices for electron flow through devices wired in the circuitwired in the circuit

EETT= E= E11=E=E22=E=E33=E=ENN

11 11 11 11 11RRTT= R= R11+R+R22+R+R33+R+RNN

IITT= I= I11+I+I22+I+I33+I+INN

Parallel Voltage in a Parallel Voltage in a circuitcircuit The voltage in a parallel circuit is The voltage in a parallel circuit is

equal to the source voltage.equal to the source voltage.

EETT= E= E11=E=E22=E=E33=E=ENN

EETT= 12v=12v=12v= 12v=12v=12v

EETT= 12v= 12v

EE11= = 12v12v

EE22= = 12v12vEE33= = 12v12v

EETT= = 12v12v

Kirchhoff’s Current Kirchhoff’s Current LawLaw The algebraic sum of all currents The algebraic sum of all currents

entering any point will equal the entering any point will equal the sum of all currents leaving that sum of all currents leaving that point.point.

IITT= I= I11+I+I22+I+I33+I+INNII11= 2A= 2A

II22= 4A= 4A

II33= 3A= 3A

IITT= 9A= 9A

Parallel Resistance in Parallel Resistance in a Circuita Circuit When resistors are connected in a parallel When resistors are connected in a parallel

circuit, the total resistance of the parallel circuit, the total resistance of the parallel circuit is always less than the smallest circuit is always less than the smallest resistance.resistance.

11 11 11 11 11RRTT= R= R11+R+R22+R+R33+R+RNN

11 11 11 11RRTT= = 22ΩΩ + + 33ΩΩ + + 66ΩΩ

11 66 44 22RRTT= 1= 122ΩΩ + + 1212ΩΩ + + 1212ΩΩ

11 1212RRTT= 12= 12Ω= Ω= 11ΩΩ

RR11= 2= 2ΩΩ

RR11= 3= 3ΩΩ

RR11= 6= 6ΩΩ

RR11= 1= 1ΩΩ

Solving for Unknown Solving for Unknown Values in a Parallel Values in a Parallel CircuitCircuit At each resistor and the total At each resistor and the total

resistors Ohm’s law should hold true.resistors Ohm’s law should hold true. The Series Circuit Principles will hold The Series Circuit Principles will hold

true.true.E=I x RE=I x R

EETT= E= E11=E=E22=E=E33=E=ENN

11 11 11 11 11RRTT= R= R11+R+R22+R+R33+R+RNN

IITT= I= I11+I+I22+I+I33+I+INN

Practice Solving the Practice Solving the CircuitCircuit

Pictorial Drawing of Pictorial Drawing of Two ReceptaclesTwo Receptacles

Schematic Drawing of Schematic Drawing of 2 receptacles2 receptacles

Schematic Drawing of Schematic Drawing of a switched receptaclea switched receptacle

Lab 7 wiring from Lab 7 wiring from SchematicsSchematics 2 switches controlling a light 2 switches controlling a light 3 switches controlling a light3 switches controlling a light

Representations Representations (cont.)(cont.) SchematicsSchematics

– Clearly showClearly show Types of devices and conductorsTypes of devices and conductors Where they should be locatedWhere they should be located Electrical ConnectionsElectrical Connections

– Typically for controls or equipmentTypically for controls or equipment– Provided by engineer, manufacturerProvided by engineer, manufacturer

2 switches controlling 2 switches controlling a lighta light

Source

Schematic

12 2/g

12 3/g

12 2

/g

3 switches controlling 3 switches controlling a lighta light

Source

Schematic