Lindsey Paul – Notes for EGB120, also called ENB120
Units:
Decibels, dB
Charge, q, 1.6022 ∙
10'() *+, Coulombs
Voltage, v, Volt
Current, i, Amperes
Energy, w, Watt
Power, p – w/t
Watt = J/s
Resistance, R - Ohms
Inductance, L - Henrys
H=Vout/Vin
KVL
Capacitance, C - Farads
KCL
Prefixes:
Giga
Mega
Kilo
Milli
G
M
K
m
^9
^6
^3
^-3
Micro
,
^-6
Nano
n
^-9
Pico
p
^-12
Femto
f
^-15
Resistors:
Terms
Passive Element
Impedance, Z
Cannot generate energy
Complex resistance, Ohms.
Captures the magnitude and
phase change associated with the
circuit element.
Gain of less than 1
A point where two or more
circuit elements join
A point where three or more
elements join
An earthed ground is literally
attached to the ground
A path with the same start and
end node
A loop that does not enclose any
other loops.
Attenuation
Node
Essential Node
Earth
Loop
Mesh
Wheatstone Bridge Circuit:
What is it?
-Can be used as a strain gauge
-Bridge is said to be balanced when
no current flows through the
ammeter
-Balance by adjusting R3
Diagram:
Main Formulae:
Current:
-=
/0
/1
, 12 =
5=
/6
Power:
9=
/6
Ohms Law:
5 = -;
Voltage:
/0
/1
(3
4
, 17 =
(8
, 1: =
3
(8
4
Mesh Analysis:
Voltage Divider
Current Divider
What is it?
Complex circuit analysis method
-must choose a ground
Steps:
-Label unknown mesh currents
-Find v across each of the circuit
elements in terms of mesh currents
Capacitor Equation:
< = +5, - = +
Inductor Equation:
5=>
/?
/1
/=
/1
, 1F = 1C/v
-Use KVL to create simultaneous
equations
-Solve for mesh currents
Lindsey Paul – Notes for EGB120, also called ENB120
Capacitors:
What do they do?
-Caps store energy as voltage
A = Area of Plates
Epsilon = Dielectric Constant
d = Distance Between Plates
E2
+=
F
Series/Parallel
Equivalent Circuits:
+GHIHJJKJ = +( + +C
+MKI?K4 = + '( + + '( '(
-=+
DC Steady State
Thevenin
Equivalent
Circuit
v is constant = open circuit
Discharged Caps are at 0V
NB
1 1
-*FP + 5(0)
+ B
1
S = +5 C , :UOOV
2
Relationship to vi
Norton
Equivalent
Circuit
5 O =
Energy in a Cap
N.B.
The r values are the same for Norton and
Thevenin
Superposition
Calculate for each invididual element.
Current sources get set to open circuits
Voltage sources get set to short circuits
Getting
Maximum
Power
From a
Thevenin
Source
F7
=0
FN
!
Natural Response of RC
Circuit – Discharging
'1
5 O = *5 0 @ W3
Tau = RC = time constant
Thevenin
Dependant
Source
E.g.
Step Response of and RC –
charging
'1
5 O = X4 ; + 7B − X4 ; @ W3
O≥0
Find the Thevenin equivalent
Inductor:
What do they do?
Series/Parallel
Which produces the following:
DC Steady State
-Store energy as current
-Cannot generate energy,
passive element
>MKI?K4 = >( + >C
>[HIHJJKJ = >'( + >'(
5=>
'(
F=0
FN
I is constant, short circuit