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Electronic InstrumentationSensors and Actuators
* In this presentation definitions and examplesfrom Wikipedia, HowStaffWorks and some other sources
were used
Lecturer: Dr. Samuel Kosolapov
Items to be defined/refreshed/discussed
• Volt-Ampere Characteristics
• Voltage and Current Sources
• Black Box Concept
• Sensors & Actuators
2
V-A (Volt-Ampere) CharacteristicsLinear V-A Characteristic:
Example: Resistor: Ohm’ law: Line
3
I
V
Line slope isG= 1/R
#1
EE will say: V-A Characteristic;
But Graph is I as a function of V
Nonlinear V-A Characteristic: Example: Zener diode
4
DC Ideal Voltage Source: definition & symbol
Voltage (Amplitude) is constant (Independent on LOAD connected)
5
The following symbol will be used for DC
“Friendly” name
Voltage
+
AC (and DC) Ideal Voltage Source: definition & symbol
Voltage (Amplitude) is constant (Independent on LOAD connected)
6
The following symbol will be usedas for DC as for AC.
V11Vac
0Vdc
“Friendly” name
+ Not always seen on printed exam
AC Amplitude VoOr V(t) or V(s)
DC Amplitude(Shift, Offset, Bias)
AC (and DC) Ideal Voltage Source: definition & symbol
Voltage (Amplitude) is constant (Independent on LOAD connected)
7
Multisim 11 provides a number of options
Multisim 11Signal Voltage Source
AC_VoltagePeak value is used
Multisim 11Power Sources
AC_VoltageRMS value is used
Ideal Voltage Source: usageVoltage (Amplitude) is constant
(Independent on LOAD connected)
8
Q1. What is the voltage on the Load ?A1: 1VQ2. And if Rload = 1 W ?
A2: 1V
The following EWB symbol will ALSO be used as for DC as for AC.(EWB): RMS Value sometimes specified (not so good for us)
Ideal Voltage Source: V-A CharacteristicsVoltage (Amplitude) is constant
(Independent on LOAD connected)V(Rload) = V(I) = Vo = const
9
I
V
Line slope is INFINITY
Vo = const
Ideal Current Source: Definition & SymbolCurrent in the LOAD (Amplitude) is constant
(Independent on LOAD connected)
10
The following symbol will be used as for DC as for AC.(Schematics, Multisim): Peak Value specified
“Friendly” nameThis + Is misleading
Arrow direction will be used in the node
equations Amplitude IoOr I(t) or I(s)
I1
0Adc
EWB
Multisim 11Misleading “+”
is omitted
Ideal Current Source: Usage & V-A Characteristics
Current in the LOAD (Amplitude) is constant (Independent on LOAD connected)
I(Rload) = I(V) = Io = const
11
I
V
Line slope is 0Is=Io = const
Practical Voltage & Current sources
12
Thevenin Model Norton ModelRs internal resistance of the Voltage (or Current) Source
SSS
S
SS IRV
R
VI
#1 Practical Voltage Source may be converted to the Practical Current Source (and vice versa).
We’ll convert Practical Voltage Source to Practical Current Sourceand back whenever it is convenient.
V-A Characteristics of Practical Voltage Source
(Ideal Voltage Source: tg(a) = INFINITY)
13
I
V
Line Slope:tg(a) = 1/Rs
Vs
V-A Characteristics of Practical Current Source
(Ideal Current Source: tg(a) = 0)
14
I
V
Line Slope:tg(a) = 1/Rs
Is
Q: Voltage or Current Source ?
15
SourceCurrentRondependencenoR
VII
thenRRif
SourceVoltageRondependencenoVVthenRRif
RR
VIIV
RR
RV
LOAD
S
SLOADS
SLOAD
LOADSLOADSLOAD
LOADS
SLOADSS
LOADS
LOADLOAD
:
)(
;
Theoretical answer: both (because conversion can be made)
Practical Answer: depending on LOAD .
Practical Voltage Source: Parameters Example: Electrochemical Battery
16
Electrochemical Battery – constant DC voltage sourceMinimal Set of Parameters:
Vs = 1.5 V (EMF) Rs ~ 2 W : depending on sizes!!! (AA, AAA),
aging: Rs grows,
Rs is small Electrochemical Battery is mostly referencedas Voltage Source. Reminder: small is comparing to the LOAD
Vs is constant (slowly fades during battery aging)
Other parameters: battery capacity (Ampere x Hours), weight, color, company name, price…
Q1. Voltmeter is connected to AA battery and shows V=1.5 V.
Can one claim: “the battery is “good” “ ?
Real battery has many properties …
Simple battery “model”Has only two parameters
Voltage or Current Source: Example: Hadera Power Station
17
AC Power Generator – Sine Wave Vs = 220 V (RMS) (Peak Voltage is ~325 V)
f = 50 Hz ( 110-127 V , 60 Hz in USA)
Rs MUST be very close to ZERO(otherwise voltage in the house
will go down), mostly VOLTAGE SOURCE
Q: Why sometimes brightness of the lampis visibly changed ?
Simple Model of “Hadera Power Station”Rs ~ 0
Voltage or Current Source: Example: Laboratory DC Power Supply
18
Laboratory (stabilized) DC power supply.
Q1. Why so expensive ? (~ 1000 NIS)
Q2. Parameters ?
Q3: Why 2 (independent) departments ?
Q4: Why and How and for What reasonEE must to restrict currentat the beginning of the lab ?
Practical or Ideal Voltage Source ?
19
V1 and V2 are Ideal Voltage Sources.V1=10V, V2 = 5V.
Q1: Vx = ?A1: . Important part of solving Electronics problem is to NEGLECT some elements of the circuit.Be careful. Think when stop neglecting.
Reminder (Deterministic) Black Box Concept
Internal Structure & Practical Implementation
(of the Black Box) is not known (or not important),
but IF the same Input signal X(t)
(say, sin wave) is applied to the input,
THEN the same Output signal Y(t)
(say, triangle wave)
always appears on the output 20
Black Box(Color of the “Box” is not
important)
Output Signal Y(t)Input Signal X(t)
Black Box Example: Voltage Divider
21
Black Box
Implementation A
Implementation B
Black Box Example: Voltage Divider
22
Q1: Is internal design really important here ?A: Depending who is asked:
EE: No. Implementation A and B behave ELECTRONICALLY the same way
Mechanical Engineer: Implementation B requires more room
Sales Manager: Implementation B is more expensive
Quality control: More elements and connections – less reliable
Reminder Black Box Concept
Private cases of Black Box:
Only Input (Signal)
or only Output (Signal)
23
Black Box Output
Black BoxInput
Black Box Example: Practical Voltage Source
Electronically
it is of no importance here
what is internal design of the Ideal Voltage Source
(while it is ideal )
24
Black Box OutputLoad
(Resistor)
Reminder Mathematical Model(of the Black Box)
• MM is a description of the system (Black Box)using exact (mathematical !) language
• Practically, MM is a set of mathematical rules/equations describing SOME (but not ALL !!!) aspects
of the system’ (Black Box) behavior.
• MM is a Rude Simplification of real object.
• Important: Non-relevant in THE current context staff is IGNORED
• BIG Question: Who, how and why decideswhat IS important and what is NOT
• Important: The same Black Box can be described by a differentmodels of a different complexity level
25
Electrical Model & Equivalent Circuit(of the Black Box)
• EM: Set of electrical/electronic rules/equations
• EM: is Rude Simplification of real object:all non-electronics features are ignored
• EC: EQUIVALENT CIRCUIT:
Visual presentation of the chosen
math/electronic model
as electrical circuit (by using standard symbols)
• Reminder: Real structure of the Black Box may be not known
Models, Equivalent circuits are used mostly for calculations
• In this sense, one can “replace” Black Box
to its equivalent circuit26
Model Example:Voltage Divider
VOUTPUT = VINPUT / 2
27
Math/Electrical Model
Equivalent Circuit
Sensor: Definition
28
Sensor:Converts SOME Energy (Signal) to ELECTRICAL Energy (Signal)Sensor in Electronics is SIGNAL SOURCE (Voltage/Current Source) To provide electric calculations:
Sensor can be replaced by its BLACK BOX MODEL / Equivalent circuit
Vs and/or Is and/or Rs are functions of time and some other parametersInput of sensor is some non-electrical signal,
only output is drawn here
Sensors
29
In the frames of FOURIER/LAPLACE approach Vs and Is are COMPLEX AMPLITUDES / MAGNITUDES on some frequency w or s.
Any signal Vs(t) is treated “as” DC (Voltage/Current) source!
Resistance may be complex (Zs instead of Rs) .
Only (complex) amplitudes are used in all intermediate calculations.
Finally: Sensor (Signal Source) is characterized by:1. Its SPECTRUM (Amplitude as function of frequency)2. Its (equivalent / internal) resistance/impedance.
Actuator (broad definition)
30
Actuator:Converts ELECTRICAL Energy (Signal) to SOME Energy (Signal)Actuator in Electronics is LOAD resistor
(complex resistance - impedance) To provide calculations:
Actuator can be replaced by its BLACK BOX MODEL / Equivalent circuit:
Finally: Actuator is characterized by its (equivalent)resistance or impedance.
Output of actuator is some non-electrical signal, only input is drawn here
Sensor: Carbon (Granular) Resistance Microphone
Carbon microphone - The oldest and simplest microphone uses carbon dust. This is the technology used in the first telephones and is still (?) used in some telephones today.
The carbon dust has a thin metal or plastic diaphragm on one side. As sound waves hit the diaphragm, they compress the carbon dust, which changes its resistance.
By running a current through the carbon, the changing resistance changes the amount of current that flows.
Google How Telephones Work for more information.
Usage & Parameters: External Battery & Resistor needed ( ~ 12 V), ( Rs ~ 100 W ).
Sensor Example: Outdated Carbon Microphone
31
Sensor: Usage ExampleReal structure Black Box Equivalent Circuit of the Carbon Microphone
32
Real physical structure of the
carbon microphone
Real appearance of the carbon
microphoneBlack Box for user
Equivalent circuit of Carbon Microphone(Including Support
Battery and resistor)
Q: Develop Theveninequivalent
Actuator ExampleElectromagnetic (Dynamic, Moving-Coil ) earphone
( RLOAD ~ 75W .. 1 kW )
33
Actuator ExampleElectromagnetic (Dynamic, Moving Coil ) speaker
( RLOAD ~ 7 W )
34
Sensor & Actuator Usage Example
35
Simple Home Telephone System:
Sensor: Carbon (Granular) Resistance Microphone (with battery !) Actuator: Electromagnetic (Dynamic) earphone
PRACTICAL TELEPHONE - View from the CUSTOMER’s point of view
Simple Home Telephone System:Warning: Long distance telephone: Line (Wire) must be replaced to RLINE
Attenuation (Speak in a loud voice)
After “replacement” one can make electrical calculations
Analog Sensor & Actuator Usage Example
36
External Battery is DC Battery.But starting from ~ 1920 HF Telephones were developedto prevent “sniffing”. Story about Stalin and Bazhanov
Sensor Example: Condenser Microphone
• A condenser microphone is essentially a capacitor, one plate of the capacitor moving
in response to sound waves. The movement changes the capacitance
of the capacitorCondenser microphones usually need a small battery
to provide a voltage across the capacitor.
• Discuss properties in the frames of box model
37
This is why You learn physics “M” And solve “dull” problems with capacitorsQ: Can anyone write relevant equationsExplaining Condenser Microphone operation ?
Sensor Example. Electret Microphone
38
An electret is a stable dielectric material with a permanently-embeddedstatic electric charge
(which, due to the high resistance and chemical stability of the material,
will not decay for hundreds of years).
Unlike other condenser microphones electret types require no polarizing voltage,
but they normally contain an integrated preamplifierwhich does require a small amount of power
Standard Electret Microphone with Arduino
39
int sensorValue;void setup(){
Serial.begin(9600); // sets the serial port to 9600}
void loop(){
sensorValue = analogRead(0); // read analog input pin 0Serial.println(sensorValue, DEC); // prints the value readdelay(100); // wait 100ms for next reading
}
Preamplifier is not enough !!!
Envelope Detector
Arduino Microphone sound sensor module
40
Details of operation: see:https://learn.sparkfun.com/tutorials/sound-detector-hookup-guide
KY-038 – Microphone Sensor KY-037 – Sensitive Microphone SensorThe only difference is KY-037 has High sensitivity
KY-038/KY-037 Microphone sound sensor module
41
Microphone here is connected without Capacitor LM393 is a voltage comparator. When the voltage of in-phase terminal (pin 3) is higher
than that of the inverting terminal (pin 2), output terminal (pin 1) will output high.
Otherwise, it outputs low. First, adjust potentiometer
to make the voltage for pin 2 of LM393 less than 5V. (LED2 will be OFF)When microphone detects “sound”
output of comparator is “HIGH” and LED2 is ON
Demonstrate with +5V and GND (without Arduino)
Arduino KY-038 Microphone sound sensor module
42
For sound detection Module has two outputs:1. AO, analog output,
real-time output voltage signal of the microphone2. DO, when the sound intensity reaches a certain threshold,
the output is high(threshold can be adjusted by potentiometer)
Connecting to the ArduinoPin + to Arduino 5+Pin to ArduinoPin A0 to Arduino A0 (for analog program)Pin D0 to Arduino 13 (for digital program)
Arduino KY-038 Microphone sound sensor module
43
Example code: Digital output
int Led = 13 ;// define LED Interfaceint dPin = 3; // define D0 Sensor Interfaceint val = 0;// define numeric variable value
void setup (){
pinMode (Led, OUTPUT) ;// LED will blinkpinMode (dPin, INPUT) ;// D0 of sensor
}
void loop (){
val = digitalRead(dPin); if (val == HIGH) // If the module detects a sound
{digitalWrite (Led, HIGH); // LED13 on
}else{
digitalWrite (Led, LOW); // LED13 off}
}
Usage of Analog output will be demonstrated later
Arduino KY-013 Analog Temperature Sensor(NTC Thermistor)
44
Thermistor resistance is changed with temperatureTemperature range: 55°C / +125°C
Accuracy: + / 0.5°C
Real-life specification of thermistors will be discussed laterMeanwhile, see Wikipedia for details
KY-013 additionally contains 10 k resistor, so that all the module operates as a plain voltage divider
Arduino pin analoog A0 -> module S (Signal)Arduino pin GND -> module “-”Arduino pin 5+ > middle pin 5V
Arduino KY-013 Analog Temperature Sensor(NTC Thermistor)
45
#include <math.h>
int sensorPin = A0; // select the input pin for the potentiometer
double Thermistor(int RawADC){
double Temp;Temp = log(10000.0*((1024.0/RawADC‐1)));Temp = 1 / (0.001129148 + (0.000234125 + (0.0000000876741 * Temp * Temp ))* Temp );Temp = Temp ‐ 273.15; // Convert Kelvin to Celcius//Temp = (Temp * 9.0)/ 5.0 + 32.0; // Convert Celcius to Fahrenheitreturn Temp;
}
Arduino KY-013 Analog Temperature Sensor(NTC Thermistor)
46
void setup(){Serial.begin(9600);
}
void loop(){
int readVal=analogRead(sensorPin);double temp = Thermistor(readVal);
Serial.println(temp); // display tempature//Serial.println(readVal); // display tempature
delay(500);}
Arduino KY-028 Temperature sensor module
47
Additionally has comparator. Connect to 5V and GND. Rotate potentiometer until LED2 is OFF.
Then “heat by fingers” LED2 will be ON.
Code: trivial
Arduino KY-001 Temperature sensor module
48
Contains specialized Dallas 18B20 module.
Operation includes 1-wire protocol will be discussed later
Sensor Example: Linear Temperature Sensor: LM35 (LM = National Semiconductor)
49
Vsensor
0
Rsensor
0k
Widely used in the student’s projects to build digital thermometer.
Black Box Model:Vsensor = 10*10-3 * T (Volt)T – temperature in C0
Only 2 out pins !!!Vs is not included !!! (Why ?)
Arduino with LM35http://www.instructables.com/id/ARDUINO-TEMPERATURE-SENSOR-LM35/
50
Connection is trivial. Some calculations are needed
Arduino with LM35http://www.instructables.com/id/ARDUINO-TEMPERATURE-SENSOR-LM35/
51
int val;int tempPin = 1;
void setup(){
Serial.begin(9600);}
val = analogRead(tempPin);float mv = ( val/1024.0)*5000;float cel = mv/10;// float farh = (cel*9)/5 + 32;
Serial.print("TEMPRATURE = ");Serial.print(cel);Serial.print("*C");Serial.println();delay(1000);
Sensor Example:Photo Diode
• Diode Non-Linear Device !!!Black-Box Model is not trivial Later
52
Important to understand: Physics: Current is EXACTLY proportional the Light IntensityBut Current is non-linear function of the Voltage (explain: photon, quantum yield)
Arduino KY-018 Photo resistor module
53
Physical Operation and real-life parameters will be discussed later
KY-023 additionally contains 10 k resistor, so that all the module operates as a plain voltage divider
Arduino pin analoog A0 -> module S (Signal)Arduino pin GND -> module “-”Arduino pin 5+ > middle pin 5V
Code is primitive
Actuator ExampleLED = Light Emission Diode
• LED (+ remote control for TV – IR = Infra Red)
• Diode Non-Linear Device !!!Black-Box Model is not trivial Later
54
Important to understand: Physics: Intensity is EXACTLY proportional to CurrentBut Current is non-linear function of the Voltage
Sensor Example: MEMS accelerometerMEMS = Micro Electro Mechanical Systems
55
Idea Design Device for amateurs Application for everyone
Q1: Does EE needs Physics “M” to invent and design new devices ?
Actuator ExampleMEMS Electrostatic Actuator : mirror
Compact Imaging Device
Model: Capacitor + ?
56
Explain how it works, why heavily heatedWhy do not start and stop Power when Projector was ON
Motivation Question
57
Electronics today is mostly DIGITAL,
But Sensors and Actuators in their’ nature are (mostly) ANALOG DEVICES !
Question: How to connect these ANALOG devices
to DIGITAL staff?
Answer: EE must know as Analog Electronicsas Digital Electronics to do that
Control Questions
• What have I learned ?
V-A characteristics
Sensor and Actuator Concepts
A number of
real sensors and actuators examples
58
Literature to read
1. TBD
59