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Flashcards in Advanced Electronics Engineering (Industrial) Deck (200):
1

It is a four layer pnpn or npnp device with a control mechanism. It is a solid-state semiconductor device similar to diode with an extra control terminal gate

Thyristor

2

The main terminals of a thyristor

Anode and cathode

3

control terminal of a thyristor

gate

4

What is the control signal for SCR?

current pulse

5

For GTO, what is the control signal?

voltage pulse

6

for LASCR, what is the control signal?

light (both light and a gate current can work to control the LASCR simultaneously)

7

In what type of applications are thyristors usually used?

High voltage and High current

8

The process where the change of polarity of the currents cause the device to automatically switch off

Zero Cross operation

9

Is the voltage that must be overcome which SCR enters the conduction region(Vak required to turn ON the thyristor)

Forward breakover voltage

10

The minimum value of Anode - Cathode current which the SCR switches from the conduction state to the forward blocking region, (required anode current for SCR to remain turned ON)

Holding Current

11

These are the regions corresponding to the open-circuit condition for the controlled rectifier which block the flow of charge (current) from anode to cathode

Forward and reverse blocking region

12

Maximum Reverse Voltage of Vak before SCR Breaks down into the Zener or avalanche region of the device

Reverse breakdown voltage

13

Power output of Thyristors

up to 4kA

14

It is a gas-filled triode vaccum tube, served as the basis for the transistor

Thyratron

15

Turn off time for SCR

5-30 μs

16

Turn off time for SCS

1-10 μs

17

Maximum anode current and Power dissipation of SCS

100-300 mA
100-500 mW
(SCS have much lower max. power dissipation than SCR)

18

It is a type of Silicon controlled Rectifier that can be turned on or off by applying a pulse of gate current and turned off by applying a pulsed negative bias

Gate Turn-Off Switch
(Highly advantageous since it can be turned on or off by applying the proper pulse polarity to gate cathode)

19

Gate triggering current for GTO

20mA

20

Gate Triggering current for SCR

30μA

21

Turn off and turn on time of GTO

1μs

22

How do you turn of an LASCS

remove or reverse the positive bias

23

This transistor has a stable negative resistance, also known as double-based diode

UJT

24

It is a four layer pnpn diode with only two external terminals. It is considered a unilateral or unidirectional break over device.

Shockley diode

25

It is a silicon diode exhibiting very high resistance up to a certain level, beyond which the device switches to low resistance conducting state

Thyrector

26

A DIAC is comparable to two ______ Conencted in reverse parallel

Shockley Diodes

27

A TRIAC is comparable to two ______ Conencted in reverse parallel

SCRs

28

It is used to assist in the turn off of Triac

snubber circuit

29

It is a unilateral or unidirectional break-over device, Similar to a Shockley Diode with a gate terminal

Silicon Unilateral Switch (SUS)

30

It is SUS connected back-to-back in parallel. It is a low-voltage and low-current device

Silicon bilateral switch (SBS)

31

Any point on the principal voltage-current characteristic for which the differential resistance is zero and where the principal voltage reaches maximum value

Breakover Point

32

A generic term for the current through the collector junction. Note: it is the current through main terminal 1 and main terminal 2 of a triac or anode and cathode of SCR

Principal Current

33

5 basic welding intervals

Squeeze
Weld
Hold
Release
Standby

34

It is defined as the difference in the measured value and the set or desired value.

Error/difference signal//deviation and system deviation

35

The condition wherein the error signal is zero

Null

36

Small error signal or system deviation where the system cannot correct anymore

Offset

37

Characteristics of a good closed-loop control system

Very small offset signal
Quick Response
High Stability

38

Modes of Control Systems

On-Off
Proportional
Proportional plus Integral
Proportional plus Derivative
Proportional plus Integral plus Derivative

39

It is a mode of control wherein the controller has only two operating states, on and off.

On-Off (also known as bang-bang control)

40

The controller has a continuous range of possible position

Proportional (P)

41

It is a proportional mode of control where wherein the controller is not only considering the magnitude of the error signal but as well as the time that it has persisted

Proportional plus Integral (PI)

42

Proportional mode of control wherein the controller is not only considering the magnitude of the error signal, but as well as its rate of change

Proportional plus Derivative(PD)

43

It is a mode of control wherein the controller considers the error signal magnitude, error signal period of occurrence, and error signal rate of change

Proportional plus Integral plus Derivative (PID)

44

It is generally due to the person using the instrument, such as incorrect reading, incorrect recording or incorrect use of instrument, AKA Human error

Gross errors

45

Absolute Error formula

E = Y - X
Y=expected value
X=measured value

46

Accuracy Formula

A = 1 - E

E = %error
A - Accuracy expressed in %

47

It converts a non electrical signal (pressure/temperature) into and electrical signal

Transducer

48

It is required to process the incoming electrical signal to make it suitable for application to the indicating device

Signal device

49

It is generally a deflection-type meter for such general-purpose instruments as voltmeters, current meters or choppers

Indicating device

50

Who patented the permanent magnet-moving-coil (PMMC)

Jacques d'Arsonval, 1881

51

An error due to the real ammeter's resistance adds to the branch, in a way that it reduces the current in any real circuit

Insertion/Resistance error

52

Meter Accuracy Formula

%A = Iwₘ / Iwₒₘ = Rₒ/(Rₒ+Rₘ)
Rₘ=meter resistance
Rₒ=resistance of the circuit

53

% Insertion error in ammeter formula

%Insertion error = ( 1 - %A)x100%

54

Ammeter shunt Resistance formula

Rₛₕ = ( Ifₛ / (Iₜ - Ifₛ) )*Rₘ

Rₛₕ=shunt resistance, Ω
Ifₛ=full scale current, A
Rₘ=meter resistance, Ω
Iₜ=New Full Scale Current/Total Current, A

55

Input resistance of the shunted meter, Rᵢₙ₍ₛₕ₎

Rᵢₙ₍ₛₕ₎ = Rₘ⋅Rₛₕ / (Rₘ+Rₛₕ) (parallel)
=Vᵢₙ/Iᵢₙ
=(Ifₛ/Iₜ)Rₘ

56

Ayrton Shunt for multiple range ammeter formula

R₍ₛₕ₎ = Rₘ / (n - 1)
n = Iₜ / Ifₛ
n - is the factor by which you increase the Full Scale Current to a new full scale current, Iₜ

57

How is a simple DC voltmeter constructed?

By placing a resistor in series(Rs) with a meter and marking the meter face to read the voltage across

58

DC Voltmeter formula for voltage

V=(Rₛ+Rₘ)*Iₘ

59

Meter Sensitivity formula of a DC Meter (ammeter, ohmmeter, voltmeter)

S=1/Ifₛ (expressed as Ω/V)
S is the reciprocal of the full-scale current of the ammeter used in voltmeter

60

Voltmeter Accuracy

%Accuracy = Vwₘ / Vwₒₘ = (Rᵢₙ / (Rᵢₙ + Rₒ))

Rin = Rvoltmeter = Rm + Rs
Ro = Resistance of circuit taken across the element/s of voltage inquiry without the influence of the Voltmeter resistance(Rm + Rs)

for 99% accuracy, Rᵢₙ>100Rₒ
for 95% accuracy, Rᵢₙ>20Rₒ

61

Voltmeter Loading Error

%E = (1 - A) x 100%

62

This device can be constructed simply with battery, an ammeter and a resistor in series

Ohmmeter

63

Meter deflection formula for Ohmmeter

D = Iu / Ifₛ= Rin / (Rin + Rᵤ)

Iu - current at Ru
Rin = Ro(adjustable resistance) + Rm(meter resistance)
Rᵤ = Load Resistance/ Resistance in question

64

AC Voltmeter - Half wave Formulas

Rₛ = (Vdc / Ifₛ) - Rₘ
=( 0.45 Vᵣₘₛ / Ifₛ) - Rₘ

Sₐc = 0.45*Sdc = 0.45 / Ifₛ

Rₛ=multiplier resistor (in series with the meter)
Ifₛ=full-scale current
Vdc=dc voltage that cause full-scale deflection
Vᵣₘₛ=ac voltage intended to measure
Sₐc=ac meter sensitivity
Sdc=dc meter sensitivity

65

AC Voltmeter-Full wave Formulas

Rₛ = (Vdc / Ifₛ) - Rₘ
=( .9 Vᵣₘₛ / Ifₛ) - Rₘ

Sₐc = 0.9S*dc = 0.9 / Ifₛ

Rₛ=multiplier resistor (in series with the meter)
Ifₛ=full-scale current
Vdc=dc voltage that cause full-scale deflection
Vᵣₘₛ=ac voltage intended to measure
Sₐc=ac meter sensitivity
Sdc=dc meter sensitivity

66

It is a DC type bridge which can accurately measure resistances. It consists of two parallel branches with each branch containing two series elements, usually resistors.

Wheatstone Bridge

67

Wheatstone Bridge formula for measuring unknown resistance

FORMULA ONLY HOLDS WHEN CURRENT ACROSS THE BRIDGE LOAD IS 0 A:

Ru = R3 * (R₁/R₂)

R3 - Adjustable resistor on the same branch of Ru
R1 and R2 - resistors that constitute the other branch of the wheatstone bridge

68

It is a simplification of the Wheatstone Bridge/ The ratio arm (R₁/R₂) is replaced by either manganin wire or german silver wire of uniform cross section with exactly 100cm long.

Slide-Wire Bridge

69

Slide Wire bridge formula

Ru=R*( [100/S] - 1 )

Ru - unknown resistance
R - Resistance on the same branch as Ru
S - the resistance on the sliding wire that pairs with R (imagine a bridge, S and R are the resistances at the bottom half of the ammeter bridge)

70

It is a modified version of the wheatstone bridge eliminating the effects of contact and lead resistance when measuring unknown low resistance

Also, determine the range of resistances it can measure

Kelvin Bridge
(1Ω to about 1μΩ))

71

Two applications of DC bridge for loop test

Murray loop method
Varley loop method

72

It is used to measure the impedance of a capacitive circuit. AKA capacitance comparison bridge/series capacitance

Similar-Angle Bridge

73

A photoelectric instrument the optical reflectance of a reflecting surface.

Reflectometer

74

In fiber optics, this instrument is used to analyze the reflected light energy and helps determine the existence and location of breaks and losses in splices and connector

Optical Time Domain Reflectometer (OTDR)

75

A Vacuum Tube Diode Employs the process of _______ to perform Diode Rectification

Thermionic Emission

76

What is Thermionic Emission

The Production of electrons through heat

77

The heating element used to heat the plate in a vaccuum tube diode operates at what voltage? Is it AC or DC?

6.3 Volts, AC

78

The Supply Voltage in a Vaccuum Tube diode is connected in what manner?

Positive at the Anode, Negative at the Cathode

79

A Vacuum tube diode with a grid terminal

Triode

80

The voltage at the grid terminal is (Positive/Negative) With respect to the cathode of the device

Negative
(Therefore, VGG is a negative supply)

81

The Voltage that controls the diode current in a vacuum tube diode

Grid Voltage (VGG, supplied by a negative voltage supply at the grid terminal)

82

The magnitude of the Supply Voltage (Vak) must be (>,

|Vak| > |VGG|

83

A Popular Circuit Breaker that uses thyristors and zener diodes

Crowbar Circuit Breaker

84

Silicon Controlled Rectifiers (SCRs) were invented at _______ in _________

Bell Telephone Labs, 1956

85

Typical Power Rating of an SCR

10 MW

86

Typical Voltage Rating of an SCR

1.8 KV

87

Typical Current Rating of an SCR

2 KA

88

Typical Max. Operating Freq. of an SCR

50 kHz

89

An SCR can be represented as a _____ and ______ Transistor in tandem

PNP, NPN

90

Two methods of turning off an SCR

- Anode Current Interruption
- Forced Commutation

91

Two Types of Anode Current Interruption

- Series Interruption (Most effective method)
- Shunt Interruption

92

In a Series Interruption method of turning off an SCR, a ________ Switch is placed in ________ to the ________

Normally Closed/Break switch
placed in series
to the anode

93

In a Shunt Interruption method of turning off an SCR, a ________ Switch is placed in ________ to the ________

Normally open/Make Switch
Placed In parallel
to the Anode-Cathode terminals of the SCR

94

Two Types of Forced Commutation

- Place an external Triggering Capacitor in parallel to an SCR (Must have opposing Voltage to Vak)

-Use an NPN Turn off circuit (Consists of [BJT switch connected to a supply voltage] in parallel to the SCR, that when turned on, opposes Vak, turning off the device)

95

Formula for the Breakback Voltage (Vbb)

Vbb = Vbrf - Vhc

Vbrf - Forward Breakover voltage
Vhc - Voltage @ Holding Current

96

Increasing the Gate Current of an SCR (increases/decreases) the required Forward Breakover Voltage for conduction

Decreases

97

The current required at the gate to sustain Anode-Cathode Conduction in an SCR

Gate Trigger Current

98

The Maximum Anode-Cathode DC Current that an SCR can withstand

Average Forward Current

99

A Silicon Controlled Switch (SCS) is a __ Terminal Device

4 (Tetrode, the only tetrode in the Thyristor Family)

100

A Silicon Controlled Switch(SCS) has ___ gate terminals

two (Anode gate and Cathode gate)

101

The advantage of an SCS compared to an SCR

Increased Control and Triggering Sensitivity

102

An SCR has a special property, where we can easily predict its __________

Firing Situation

103

Describe the Firing Situation

-There is a certain firing angle α, where during this period, the device does not conduct. Only after the Firing angle does the output waveform appear. this non-conduction portion repeats every cycle of the waveform
-Looks like a "Vertical Clipping" of the waveform

104

Describe the Firing angle(α)

α is a period of time in a waveform, expressed as an angle (Radians), where 2π represents the angle for the whole period, and π represents the halfwave period

During the Firing angle α, the output of the device is non-conductive (No waveform appears)

105

A GTO (Gate Turn Off Switch) is usually doped (heavier/lighter) than a normal thyristor

Lighter

106

Lighter Doping in the GTO will result into a (lower/higher) AK Resistance

Higher

107

The required current for Turn-on/Turn-off at the gate of a GTO must be (______) * (Anode-Cathode Current)

1/5 * Anode-Cathode Current

108

Anoter name for the shockley diode

4 layer diode

109

A Shockely Diode has __ Gate terminals

0 (No gate teminal)

110

A Shockley Diode is similar to an SCR, only that a Shockley Diode has a ________

Fixed Forward Breakover Voltage (since there is no control gate terminal)

111

Typical Forward Breakover Voltage of a Shockley Diode

60 Volts

112

DIACs have ___ Gate Terminals

0 (No Gate terminals)

113

DIACs have ___ Forward Breakover Voltages

two fixed Vbrf (one Vbrf in the positive half cycle, another Vbrf in the negative half cycle)

114

Typical Forward Breakover Voltage of a DIAC

20-40V

115

A TRIAC has ____ Forward Breakover Voltages

Two Variable Vbrf (one Vbrf in the positive half cycle, another Vbrf in the negative half cycle)

Vbrf controlled by gate current)

116

A TRIAC has ______ Gate terminals

One (simultaneously and equally controls Vbrf's in both current directions)

117

A Silicon Bilateral Switch (SBS) can operate Alternating Current.
True or False?

True

118

Both SUS and SBS have __ Gate terminals

one

119

SBSs are normally used to trigger ________

TRIACS and Control Systems

120

SBSs have a more pronounced _________

Negative Resistance Region

121

The 'AC' in TRIAC and DIAC stands for _______

Alternating Current

122

A Unijunction Transistor has ____ Terminals

3 (Emitter, Base 1, Base 2)
Hence its other name, Double Based Diode

123

A Unijunction Transistor has ____ Layers of semiconductors

2 layers (one P-type, one N-type)

124

A Programmable UJT (PUT) have _____ Layers of Semiconductors

4 layers (Similar to SCR)

125

The Gate Terminal of a PUT is located at the (anode/cathode) gate

Anode Gate
(For an SCR, the gate terminal is located at the Cathode gate. That is the only physical difference of an SCR and a PUT)

126

What is the required condition for PUT Conduction?

When Vak > Vgate

Vgate controlls the turn on voltage

127

A DIAC and a TRIAC have ____ anodes

two anodes (A1 and A2)

128

Three functions of Instruments

- Indicating
- Controlling
- Recording

129

The Comparison of a quantity to an accepted standard quantity

Measurement

130

Governing Body that Facilitates International Standards

International Bureau of Weights and Measures (Located in Paris)

131

Pertains to standards at a National Level

Primary Standards

132

Standards in Industrial Labs, in which measuring tools are calibrated based on Primary Standards

Secondary standards

133

Standards in General Laboratory Instrument Calibrations

Working Standards

134

Three Categories of Error

- Gross Error
- Systematic Error
- Random Error

135

Errors that persist due to the instruments and/or the environment

Systematic Error

136

The accumulation of small, unavoidable errors

Random Error

137

Formula for % Error

%E = (Absolute error / Expected Value) x100%

138

Formula for Presicion

Note: Requires a sample space/set of data

P = 1 - abs| (Xn - Xn(bar)) / Xn(bar) |

Xn - Datapoint in inquiry
Xn(bar) - Mean Value of data points

139

Three types of DC meters

- Permanent Magnet Moving Coil (PMMC, D'Arsonval)
- Iron Vane
- Electrodynamometer

140

Two types of moving coils in a DC meter

- Jewel and Pivot
- Taut Band Suspension

141

Maximum Full Scale Current of a Jewel and Pivot moving coil

Ifs = 50μA

142

Maximum Full Scale Current of a Taut Band Suspension moving coil

Ifs = 2μA

143

The Advantages/Disadvantages of a Taut Band Suspension VS Jewel and Pivot

ADV: More sensitive
DISADV: More Expensive

144

Part of a PMMC that is attached to the needle tail, and eliminates the gravitational influence on the needle

counterweight

145

Part of a PMMC that counters the deflecting force of the electromagnetic force

Spring

146

Part of a PMMC that contains a pivot, which will allow movement proportional to the current passing through it

moving coil

147

Part of a PMMC that provides the visual indicator of measurement

Pointer

148

Part of a PMMC meter that provides the magnetic field for the moving coil

magnet

149

Part of the PMMC that allows pointer calibration for re-positioning to initial position when Current through the moving coil is zero

Zero Adjustable Control

150

The 3 Forces involved in a PMMC

- Deflecting Force
- Damping Force
- Controlling Force

151

The force in a PMMC that prevents pointer oscillation

Damping Force

152

The force that returns the pointer to initial position @ I = 0A

Controlling Force

153

Force exerted by the moving coil in the presence of a current through it

Deflecting Force

154

The most Basic DC Metter

Ammeter

155

The current through the moving coil that causes Full Scale Deflection of the pointer

Full scale current (Ifs)

156

An Ideal ammeter have the following properties:

- Meter resistance (Rm) is equal to zero
- deflection is linearly proportional to current through the moving coil

157

Error in measurement attributed to inaccurate meter face, not properly marked

Calibration Error

158

Formula for Calibration Error

CE = +- 3% of Ifs

159

Insertion Error is usually expressed in _______

% Accuracy

160

For a DC Meter, the Ideal Accuracy/ Ideal Error is:

100% Accuracy, 0% Error

161

In order to obtain 'n'% Accuracy, Rwom must be ___ times greater than the Meter Resistance (Rm)

For 'n'% Accuracy:

Rwom = n*Rm

Rwom - Resistance without the meter
Rm - Meter Resistance
n - desired percentage of accuracy(do not include %; ex. for 99% accuracy, Rwom = 99*Rm)

162

An Ammeter Configuration that allows a greater current measurement

Ammeter Shunt (Shunting an Rsh to the ammeter)

163

When the load changes, the Full scale current of a DC meter __________

DOES NOT CHANGE
(Ifs is an unchanging inherent property of the meter alone)

164

With an ammeter, The higher the resistance of the circuit to be measured (Rwom) is compared to the Meter Resistance (Rm), the higher the __________ will become

Accuracy

165

When we are to design an ammeter that can detect a new Full Scale Current (Iₜ2) that is 'n' times greater than the current full scale current (Iₜ1) of a specific ammeter(that has an existing shunt resistor (Rsh1) designed for Ifs1), what is the value of the new shunt resistor to adjust for the new Iₜ2 current?

If Iₜ1 is to become Iₜ2 = n*Iₜ1, then the new resistor shunt is to be changed from Rsh1 to:

Rsh2 = Rsh1 / n

166

The Shunt resistance must be _______ than Meter Resistance

Much much lesser

167

Two Types of Multirange Ammeters

- Switched Shunt
- Ayrton Shunt

168

Disadvantage of a Switched Shunt

There are moments when a shunt resistor will not stay shunted to the meter when transitioning from one shunt resistor to another, allowing all the current to pass through the meter, damaging it

169

Advantage of an Ayrton Shunt

while switching, there is no instance that there is no shunted resistance to the ammeter, preventing damage

170

The Shunt Resistances in the Ayrton Shunt are connected in ________

Series

171

The Voltmeter Resistance (Rin = Rm +Rs) is ideally

∞ Ohms

172

Formula for Series Resistance of Voltmeter

Derived from Voltmeter Voltage Formula:

Rs = (Vt / Ifs) - Rm

173

The Ohmmeter resistance (Ro) is adjustable because it is used to:

Correct for battery aging

174

How is the Adjustable Ohmmeter resistance (Ro) adjusted?

1.) Short the Ohmmeter
2.) Adjust the Adjustable Ohmmeter Resistance (Ro) until full scale deflection is achieved in the face of the meter

Formula for Ro when voltmeter is shorted
Ro = (Vaged / Ifs ) - Rm

Vaged - the current voltage of the aged battery
Ifs - fullscale curent (remember, this property does not change regardless of battery aging or load)
Rm - meter resistance

3.) Un-short the ohmmeter

175

The Value of Deflection Factor(D) when Ru(unknown resistance) is 0 ohms (short circuit)

D = 1

176

The Value of Deflection Factor(D) when Ru(unknown resistance) is (Rin / 3) ohms

(Rin = Ro (adjustable resistance of ohmmeter) + Rm(meter resistance)))

D = 0.75

177

The Value of Deflection Factor(D) when Ru(unknown resistance) is (Rin) ohms

(Rin = Ro (adjustable resistance of ohmmeter) + Rm(meter resistance)))

D = 0.5

178

The Value of Deflection Factor(D) when Ru(unknown resistance) is (3*Rin) ohms

(Rin = Ro (adjustable resistance of ohmmeter) + Rm(meter resistance)))

D = 0.25

179

The Value of Deflection Factor(D) when Ru(unknown resistance) is (∞) ohms (open circuit)

(Rin = Ro (adjustable resistance of ohmmeter) + Rm(meter resistance)))

D = 0

180

A Deflection Factor of 1 means that the pointer is located at the __________ of the meter face

Rightmost portion of the meter face

181

A Deflection Factor of 0 means that the pointer is located at the __________ of the meter face

Leftmost portion of the meter face

182

What Device is placed in series with a DC Voltmeter circuit to become an AC Halfwave Voltmeter

Diode

183

What Device is placed in series with a DC Voltmeter circuit to become an AC Fullwave Voltmeter

Transformer + Diode Bridge Curcuit

or

Center tapped transformer with two diodes

184

A Peak Detector consists of:

A diode-capacitor circuit (looks like a clamper)
and a Voltmeter across the capacitor

185

The most accurate type of DC meter

DC Bridge Meter

186

When a bridge is balanced in a DC Bridge meter, the load in between the two nodes will have a current of _____ amperes through it

0

187

Following up on the fact that the bridge is balanced, and that the current through the load is 0 A, what can you say about the voltages on either end nodes of the load resistor?

they are equal in value

188

in a Wheatstone Bridge, what is the element connected as the "Bridge" of the circuit?

Ammeter (Checks if current at bridge is 0A, to determine if the bridge is balanced)

189

A DC Bridge used to measure fault distances

Varley Loop

190

A DC Bridge used to measure fault distances, but it is a simplified varley loop

Murray Loop

191

A wheatstone bridge used to measure reactances and impedances

AC Bridges

192

The AC Bridge that measures an unknown Inductance given a capacitance in its branch

Maxwell Bridge

193

Maxwell Bridge Construction

1st branch, above: Capacitor || potentiometer
1st branch, below: potentiometer
2nd branch, above: Fixed Resistor
2nd Branch, below: unknown Inductor (including coil resistance in series)

194

The AC Bridge that is similar to the Maxwell Bridge, but the branch where a potentiometer and a capacitor are in parallel, is connected in series instead

Hay Bridge

195

Maxwell Bridge Construction

1st branch, above: Capacitor in series with potentiometer
1st branch, below: potentiometer
2nd branch, above: Fixed Resistor
2nd Branch, below: unknown Inductor (including unknown coil resistance in series)

196

The AC Bridge extensively used for measuring capacitances and dissipation factors

Schering Bridge

197

Schering Bridge Construction

1st branch, above: Variable Capacitor || fixed resistor
1st branch, below: Fixed capacitor
2nd branch, above: Fixed Resistor
2nd Branch, below: unknown Capacitor (including unknown stray resistance in series)

198

The AC Bridge extensively used to measure Frequency

Wein Bridge

199

Wein Bridge Construction

1st branch, above: Capacitor(C1A) in series with fixed potentiometer(Rpot1A)
1st branch, below: Capacitor(C1B) || with fixed potentiometer(Rpot1B)
2nd branch, above: Fixed Resistor(Rfix2A)
2nd Branch, below: Fixed Capacitor(Rfix2B)

UNKNOWN: Frequency of the AC source connected to the circuit

200

Formula for frequency measured by a wein bridge

1.) Adjust potentiometers so that Bridge is balanced:

Rfix2A / Rfix2B = (Rpot1A / Rpot1B) + (C1B / C1A)

2.) f = 1 / { 2π*sqrt(C1A * C1B * Rpot1A * Rpot1B) }