ElektronikaElektronika

Guru Mata Pelajaran :Guru Mata Pelajaran :Onie Meiyanto, S.Pd.Onie Meiyanto, S.Pd.

Jadual Pelajaran :Jadual Pelajaran : Senin jam ke- 6,7 Senin jam ke- 6,7

E-mail: E-mail: onie_204onie_204@yahoo.com

SMA “MIMI”SMA “MIMI”SurabayaSurabaya

Basic electronicsBasic electronics

Ohm’s lawOhm’s lawCurrent = voltage / resistanceCurrent = voltage / resistance I = V / RI = V / R V = I x RV = I x R

Definitions Definitions Voltage = potential energy / unit charge, units = VoltsVoltage = potential energy / unit charge, units = Volts Current = charge flow rate, units = AmpsCurrent = charge flow rate, units = Amps Resistance = friction, units = OhmsResistance = friction, units = Ohms

ExampleExample Voltage drop when current flows through resistorVoltage drop when current flows through resistor VV11 - V - V22 = I R = I R

IR

V1

V2

Schematics Schematics Symbols represent circuit elementsSymbols represent circuit elements Lines are wiresLines are wires

+ Battery

Resistor

Ground

+V RI

Sample circuit

Ground voltagedefined = 0

Parallel and series resistorsParallel and series resistorsSeriesSeries same current flows through allsame current flows through allParallelParallel save voltage across allsave voltage across all

+

Note: these points are connected together

I

VR1

R2

Series circuitV = R1 I + R2 I = Reff IReff = R1 + R2

Parallel circuitI = V/R1 + V/R2 = V/Reff 1/Reff = 1/R1 + 1/R2

+V

R1R2I1 I2

I

Resistive voltage dividerResistive voltage divider Series resistor circuitSeries resistor circuit Reduce input voltage to desired levelReduce input voltage to desired level Advantages: Advantages:

simple and accuratesimple and accurate complex circuit can use single voltage sourcecomplex circuit can use single voltage source

Disadvantage: Disadvantage: dissipates powerdissipates power easy to overloadeasy to overload need Rneed Rloadload << R << R22

New schematic symbol:external connection

+

Vin

R1

R2 I

I Vout

Resistive dividerI = Vin/Reff = Vout/R2

Vout = Vin (R2 / (R1 + R2) )

Variable voltage dividerVariable voltage divider Use potentiometer (= variable resistor)Use potentiometer (= variable resistor) Most common: constant output resistanceMost common: constant output resistance

+

Vin Rvar

Rout I

IVout

Variable voltage dividerVout = Vin (Rout / (Rvar + Rout) )

New schematic symbol:potentiometer

Capacitors Capacitors Charge = voltage x capacitanceCharge = voltage x capacitance Q = C VQ = C VDefinitions Definitions Charge = integrated current flow , units = Coloumbs = Amp - secondsCharge = integrated current flow , units = Coloumbs = Amp - seconds I = dQ/dtI = dQ/dt Capacitance = storage capacity, units = FaradsCapacitance = storage capacity, units = FaradsExample Example Capacitor charging circuitCapacitor charging circuit Time constant = RC = Time constant = RC =

Capacitor charging circuitV = VR + VC = R dQ/dt + Q/CdQ/dt + Q/RC = V/RQ = C V (1 - exp(-t/RC))Vout = Vin (1 - exp(-t/RC))

New schematic symbol:capacitor

+V RC

I Vout

Q

Vout

t

Vin

= RC

Capacitor charging curvetime constant = RC

AC circuitsAC circuits Replace battery with sine (cosine) wave sourceReplace battery with sine (cosine) wave source V = VV = V00 cos(2 cos(2 ff t) t)Definitions Definitions Frequency Frequency ff = cosine wave frequency, units = Hertz = cosine wave frequency, units = Hertz Examples Examples Resistor response: I = (VResistor response: I = (V00/R) cos(2 /R) cos(2 ff t) t) Capacitor response: Q = CVCapacitor response: Q = CV00 cos(2 cos(2 ff t) t)

I = - 2 I = - 2 ff CV CV00 sin(2 sin(2 ff t) t) Current depends on frequencyCurrent depends on frequency negative sine wave replaces cosine wave negative sine wave replaces cosine wave - 90 degree phase shift = lag- 90 degree phase shift = lag

V0 cos(2 f t)

RI = (V0/R) cos(2 f t)

Resistive ac circuit

New schematic symbol:AC voltage source

V0 cos(2 f t)

CI =

- 2 f CV0 sin(2 f t)

Capacitive ac circuit• 90 degree phase lag

Simplified notation: ac-circuitsSimplified notation: ac-circuits V = VV = V00 cos(2 cos(2 ff t) = V t) = V00 [exp(2 [exp(2 j j ff t) + c.c.]/2 t) + c.c.]/2 Drop c.c. part and factor of 1/2Drop c.c. part and factor of 1/2 V = VV = V00 exp(2 exp(2 j j ff t) t) Revisit resistive and capacitive circuitsRevisit resistive and capacitive circuits Resistor response: I = (VResistor response: I = (V00/R) exp(2 /R) exp(2 j j ff t) = V / R = V/ Z t) = V / R = V/ ZRR Capacitor response: I = 2 Capacitor response: I = 2 j j ff CV CV00 exp(2 exp(2 j j ff t) = (2 t) = (2 j j ff C) V = V/ Z C) V = V/ ZCC

Definition: Impedance, Z = effective resistance, units OhmsDefinition: Impedance, Z = effective resistance, units Ohms Capacitor impedance Capacitor impedance ZZCC = 1 / (2 = 1 / (2 jjff C) C) Resistor impedance Resistor impedance ZZRR = R = RImpedance makes it look like Ohms law applies to capacitive circuits alsoImpedance makes it look like Ohms law applies to capacitive circuits also Capacitor response I = V / ZCapacitor response I = V / ZCC

Explore capacitor circuitsExplore capacitor circuitsImpedance ZImpedance ZCC = 1/ (2 = 1/ (2 jjff C) C) Limit of low frequency Limit of low frequency ff ~ 0 ~ 0

ZZCC --> infinity --> infinity Capacitor is open circuit at low frequencyCapacitor is open circuit at low frequency

Limit of low frequency Limit of low frequency ff ~ infinity ~ infinity ZZCC --> 0 --> 0 Capacitor is short circuit at low frequencyCapacitor is short circuit at low frequency

V0 cos(2 f t)

CI = V/ZC

Capacitive ac circuit

Revisit capacitor charging Revisit capacitor charging circuitcircuit

Replace C with impedance ZReplace C with impedance ZCC

Charging circuit looks like voltage dividerCharging circuit looks like voltage divider VVoutout = V = Vinin (Z (ZCC / (Z / (ZRR + Z + ZCC) ) = V) ) = Vinin / (1 + 2 / (1 + 2 jjff R C ) R C )

Low-pass filterLow-pass filterCrossover when Crossover when ff = = 1 / 2 1 / 2 R C = R C = 1 / 2 1 / 2 , , is time constant is time constant lower frequencies Vlower frequencies Voutout ~ V ~ Vinin = pass band = pass band higher frequencies Vhigher frequencies Voutout ~ V ~ Vinin / (2 / (2 jjff R C ) = attenuated R C ) = attenuated

Capacitor charging circuit= Low-pass filter

Vin = V0 cos(2 f t)

RC

I Vout

Ilog(Vout)

log(f )

logVin

f = 1 / 2

Low-pass filter response• time constant = RC =

Single-pole rolloff6 dB/octave= 10 dB/decade

knee

Inductors Inductors

Capacitor charging circuit= Low-pass filter

Vout

log(Vout)

log(f )

logVin

f = R / 2 jL

High-pass filter response

Voltage = rate of voltage change x inductanceVoltage = rate of voltage change x inductance V = L dI/dtV = L dI/dtDefinitions Definitions Inductance L = resistance to current change, units = HenrysInductance L = resistance to current change, units = HenrysImpedance of inductor: Impedance of inductor: ZZLL = (2 = (2 jjff L) L) Low frequency = short circuitLow frequency = short circuit High frequency = open circuitHigh frequency = open circuitInductors rarely usedInductors rarely used

Vin = V0 cos(2 f t)

RL

I

INew schematic symbol:Inductor

Capacitor filters circuitsCapacitor filters circuits Can make both low and high pass filtersCan make both low and high pass filters

Low-pass filterVin = V0 cos(2 f t)

RC

I Vout

I

High-pass filterVin = V0 cos(2 f t)

CR

IVout

I

log(Vout)

log(f )

logVin

f = 1 / 2

Gain response

log(Vout)

log(f )

logVin

f = 1 / 2

Gain response

knee

phase

log(f )

f = 1 / 2

Phase response

-90 degrees

phase

log(f )

f = 1 / 2

Phase response

-90 degrees

0 degrees 0 degrees

Summary of schematic Summary of schematic symbolssymbols

+Battery Resistor

Ground

Externalconnection

Capacitor AC voltagesource

Inductor

Non-connecting wires -

+Op amp

Potentiometer

Potentiometer2-inputs plus

center tap

Diode

Color codeColor code Resistor values determined by colorResistor values determined by color Three main bandsThree main bands

1st = 1st digit1st = 1st digit 2nd = 2nd digit2nd = 2nd digit 3rd = # of trailing zeros3rd = # of trailing zeros

ExamplesExamples red, brown, blackred, brown, black 2 1 no zeros = 21 Ohms2 1 no zeros = 21 Ohms yellow, brown, greenyellow, brown, green 4 1 5 = 4.1 Mohm4 1 5 = 4.1 Mohm purple, gray, orangepurple, gray, orange 7 8 3 = 78 kOhms7 8 3 = 78 kOhms

Capacitors can have 3 numbersCapacitors can have 3 numbers use like three colorsuse like three colors

Color

blackbrownredorangeyellowgreenbluevioletgray white

Number

0123456789