Transcript Resistance - XAMK Moodle

Resistance
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Natural feature of materials
Metals are good conductors and non metal are insulators
Voltage dependent resistors (VDR)
Temperature dependent resistors (NTC or PTC resistors)
l
R
A
Typical resistivity
Material
Resistivity
Material
Resistivity
Silver
1,64 E10-8
Nichrome
100E10-8
Copper
1,72E10-8
Silicon
2500
Aluminium
2,83E10-8
Paper
10E10
Iron
12,3E10-8
Mica
5E11
Constantan
49E10-8
Quarz
1E17
Rsistors in parallel and in series
1
1
1
1
 

 ...
Rtot R1 R2 R3
Rtot  R1  R2  R3  ...
Capacitors
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Component can store charge
How much capacitor can store charge
 Capacitors ability to collect electrons
 Capacitance
 Voltage over the capacitor
Q
C
V
C   0 r
A
d
Capacitors in parallel and in series
Ctot  C1  C2  C3  ...
1
Ctot  1 1 1
C1  C2  C3 ...
Different types of capacitors
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Big electrolyte capacitors
Tantalum caoacitors
Signal conditioning capacitors made from plastic or ceramic
Aluminium electrolyte capacitors
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Cylindrical shape and big size
They are polarized
Typical values 100 nF to 4700μF
Typical maximum voltage value 12V,16V, 32V, 64V
Made of long sheet of coated plastic film
Insulating material is non conducting liquid
Tantalum capacitors
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Low voltage devices
Capacitance 1μF – 150μF
Stable capacitance and very low impedance in low frequencies
Dont like voltage spikes
Can be exploded if connected wrong way into the circuit
Plastic capacitors
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Typical materials polystyrene, polyester, polypropylene or teflon
Capacitance 1 nF – 50μF
Ceramic and mica capacitors
Coils or Inductors
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The DC current through a coil forms an electric magnet
Short circuit for DC, AC signal properties used in electronics
Series and parallel connections are calculated like resistors
di
vL
dt
wL 
1 2
Li
2
Transformers
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When two coils are put close to each otherby mutual inductance the
energy is transferred from one coil to the other
V1 N1

V2 N 2
I1 N1

I2 N2
RLC-circuits
Material type
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Conductrors (resistivity about 10E-7 Ωm)
Insulators
Semi conductive materials (resistivity over 10E10Ωm)
 Germanium was the first
 Silicon has replace germanium
 Compaund semiconductors (GaAs)
 P-type semiconductors (holes are the majority carriers(
 N-type semiconductors (electrons are the majority carriers)
Diodes
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P-type end is anode and n-type is cathode
Voltage over zener-diode does not depend on the current passing the
component
Light emitting diodes (LED)
NPN and PNP transistors
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Transistor is a current controlled current source
The transistor can be used as a switch or as an amplifier
Integrated circuits
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Include many integrated components (divided by the amount of transistors)
 SSI small (operational amplifiers, regulators)
 MSI medium
 LSI large scale (processors)
 VLSI
Operational amplifiers
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Used to amplify signals instead of transistor amplifiers
Filter circuits
Integrators
derivators
Inverting amplifier
Rf
vout
G

vin
R1
Noninverting amplifier
Rf
vout
G
 1
vin
R1
Summing amplifier
vout 
Rf
R1
 v1 
Rf
R2
 v2 
Rf
R3
 v3  ...
Differential amplifier
vout 
Rf
R
 (v2  v1 )
Integrator
Derivator