Uploaded by tomster246

AMERC Formula sheet

advertisement
AMERC: Electronic Principles formula sheet
Ohms law:
Ohms law
𝑉 = 𝐼𝑅 (V)
Voltage divider
π‘‰π‘œπ‘’π‘‘ = 𝑉𝑖𝑛 × π‘…
Resistors:
In series
In parallel
π‘…π‘‘π‘œπ‘‘π‘Žπ‘™ = 𝑅1 + 𝑅2 + 𝑅𝑛 …
(Ω)
−1
−1
−1
−1
π‘…π‘‘π‘œπ‘‘π‘Žπ‘™ = (𝑅1 + 𝑅2 + 𝑅𝑛 … )
𝑅2
1 +𝑅2
(V)
(Ω)
KCL:
For two DC loops, the currents 𝐼1 and 𝐼2 in each branch can be generalised as a set of simultaneous
equations in the form:
𝑉1 = 𝐼1 (𝑅1 + 𝑅2 ) + 𝑅2 𝐼2
𝑉2 = 𝑅2 𝐼1 + 𝐼2 (𝑅2 + 𝑅3 )
Where: 𝑅1 , 𝑅2 , 𝑅3 are the resistance values on the diagram and 𝑉1 , 𝑉2 are the voltages of the two DC
sources.
Power:
In general
𝑃 = 𝐼𝑉, 𝑃 = 𝐼 2 𝑅, 𝑃 =
𝑉2
𝑅
(W)
Capacitors:
𝑄
𝑉
Capacitance
𝐢=
In series
In parallel
πΆπ‘‘π‘œπ‘‘π‘Žπ‘™ = (𝐢1−1 + 𝐢2−1 + 𝐢𝑛−1 … )−1
πΆπ‘‘π‘œπ‘‘π‘Žπ‘™ = 𝐢1 + 𝐢2 + 𝐢𝑛 …
Energy stored
𝐸=
Charge stored
𝑄 = 𝐢𝑉
(F)
1
𝐢𝑉 2
2
(F)
(F)
(J)
(C)
π‘„π‘‘π‘œπ‘‘π‘Žπ‘™
𝐢
Voltage across a capacitor
𝑉𝑐 =
RC, RL Circuits:
Time constant (RC)
𝜏 = 𝑅𝐢
(V)
(s)
𝐿
𝑅
Time constant (RL)
𝜏=
RC charging equation
𝑉𝑐 = 𝑉0 (1 − 𝑒)−𝑅𝐢 , 𝐼𝑐 = 𝐼0 𝑒 −𝑅𝐢
RC discharging equation
𝑉𝑐 = 𝑉0 𝑒 −𝑅𝐢 , 𝐼𝑐 = 𝐼0 (1 − 𝑒)−𝑅𝐢
RL charging equation
𝑉𝐿 = 𝑉0 𝑒 − 𝐿 , 𝐼𝐿 = 𝐼0 (1 − 𝑒)− 𝐿
RL discharging equation
𝑉𝐿 = −𝑉0 (1 − 𝑒)− 𝐿 , 𝐼𝐿 = 𝐼0 𝑒 − 𝐿
(s)
𝑑
𝑑
𝑑
𝑑
𝑅𝑑
𝑅𝑑
𝑅𝑑
𝑅𝑑
Op-Amps:
π‘‰π‘œπ‘’π‘‘
)
𝑉𝑖𝑛
Gain in general
𝐴𝑣 = (
Non-Inverting
π‘‰π‘œπ‘’π‘‘ = 𝑉𝑖𝑛 × (1 + 𝑅𝑓) (V)
Inverting
Summing
𝑅
𝑅𝑓
2
π‘‰π‘œπ‘’π‘‘ = 𝑉𝑖𝑛 × −(𝑅 )
(V)
2
𝑅𝑓
π‘‰π‘œπ‘’π‘‘ = −(
𝑅1
× π‘‰1 +
𝑅𝑓
𝑅2
× π‘‰2 +
𝑅𝑓
𝑅𝑛
× π‘‰π‘› … )
(V)
AC:
2πœ‹
, (s)
πœ”
πœ”
1
,𝑓 = 𝑇
2πœ‹
Time period
𝑇=
Frequency
𝑓=
Equation of an AC waveform
𝑉𝑑 = π‘‰π‘π‘˜ sin(πœ”π‘‘ + πœ™), 𝐼𝑑 = πΌπ‘π‘˜ sin(πœ”π‘‘ + πœ™)
RMS
π‘‰π‘Ÿπ‘šπ‘  =
Capacitive reactance
𝑋𝐢 =
Inductive reactance
𝑋𝐿 = 2πœ‹π‘“πΏ
Impedance
Phase angle
Current
𝑍=
πœ” = 2πœ‹π‘“
(Hz)
π‘‰π‘π‘˜
(V)
√2
1
2πœ‹π‘“πΆ
√𝑅 2
(Ω)
(Ω)
+ (𝑋𝐢 − 𝑋𝐿 )2 (Ω)
NB. 𝑋𝐢 > 𝑋𝐿
𝑋 −𝑋
πœ™ = tan−1 ( 𝐢 𝑅 𝐿 )
𝑉
𝐼 = 𝑍 (A)
Resonance
𝑋𝐢 = 𝑋𝐿
Resonant Frequency
𝑓=
1
2πœ‹√𝐿𝐢
Q-factor
𝑄=
1
𝑅
(Hz)
𝐿
× √𝐢
Transformers:
Voltage-turns Relationship
Current relationship
Matching
𝑉𝑝
𝑉𝑠
=
𝑁𝑝
𝑁𝑠
𝑉𝑝 𝐼𝑝 = 𝑉𝑠 𝐼𝑠
𝑍𝑝
𝑍𝑠
𝑁
= ( 𝑝 )2
𝑁𝑠
dB’s
𝑃
As a function of Power
10log ( π‘ƒπ‘œπ‘’π‘‘ )
As a function of voltage/current
𝑉
𝐼
20 log ( π‘‰π‘œπ‘’π‘‘ ) , 20 log ( πΌπ‘œπ‘’π‘‘ )
𝑖𝑛
𝑖𝑛
𝑖𝑛
Power Supplies:
Ripple voltage
π‘‰π‘Ÿπ‘–π‘π‘π‘™π‘’ =
𝐼𝐿 𝑇
𝐢
𝐼𝐿 = Load current, 𝑇 = time period
Wien bridge oscillators:
1
2πœ‹π‘…πΆ
Frequency
𝑓=
Minimum gain
𝐴𝑣 > 3
(Hz)
Boolean Logic:
AND 𝑄 = 𝐴 βˆ™ 𝐡
OR
𝑄 =𝐴+𝐡
NOT 𝑄 = 𝐴̅
NAND 𝑄 = Μ…Μ…Μ…Μ…Μ…Μ…
π΄βˆ™π΅
XOR
𝑄 = 𝐴⨁𝐡
Μ…Μ…Μ…Μ…Μ…Μ…Μ…
XNOR 𝑄 = 𝐴⨁𝐡
Diodes & transistors
Silicon diode volt drop
NPN transistor (When saturated)
PNP transistor (When saturated)
We assume that
≈ 0.7 (V)
𝑉𝑒 = 𝑉𝑏 − 𝑉𝑏𝑒 (V)
𝑉𝑒 = 𝑉𝑏 + 𝑉𝑏𝑒 (V)
𝐼𝑒 = 𝐼𝑐
NB. 𝑉𝑏𝑒 is typically 0.7 V
NB. 𝑉𝑏𝑒 is typically 0.7 V
Download