Download ME 106 Basic Electronics

Basic Electronics Review
B. Furman
25AUG2015
Lecture Flow Today
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Items to focus on this week
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Lab 1
PortMaster build
HW 1 and Questionnaire due Thursday
Term Project overview + video of past projects
Basic electronics review:

Voltage, current, resistance, capacitance, inductance
 Equivalent resistance
 Voltage divider
 Impedance of a capacitor
Learning Objectives
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
Get prepared for Lab 1 and started on PortMaster build
Get started on the term project
Explain in simple terms what is meant by:


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
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Voltage
Current
Ground
Resistor, Capacitor, Inductor
Impedance
Power
Determine equivalent series and parallel impedances
Explain the significance of a voltage divider
Derive an expression for the impedance of a capacitor
Mechatronics Concept Map
Power
Source
User
Interface
ME 106
ME 120
Controller
(Hardware & Software)
ME 106
Power
Interface
INTEGRATION
ME 106
ME 154
ME 157
ME 195
Signal
Conditioning
ME 106
ME 190
ME 187
ME 106
ME 120
Actuator
Sensor
ME 120
ME 297A
System to
Control
ME 110 ME 182
ME 136 ME 189
ME 154 ME 195
ME 157
BJ Furman 22JAN11
Lab 1 – Intro to the Mechatronics Lab
Read and
prepare
 Take the pre-lab
quiz before you
start your lab
session

PortMaster
Solder practice
 Bit manipulation
and port IO
learning

HW 1 and Questionnaire
When are they due?
 Hard and softcopy for Questionnaire
 Soft copy only for HW questions

Term Project Overview

See the guideline:
http://www.engr.sjsu.edu/bjfurman/courses/ME1
06/ME106pdf/ME106termproject.doc

Video sample of previous projects
Key Concepts
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Voltage
Ground
Current
Resistor
Capacitor
Inductor
Impedance
Power



Take out a sheet of paper
Explain the concepts in
terms that a 6th grader
could understand
First, work on your own,
then, introduce yourself to
someone you have NOT
met yet, and share your
answers.
Basic Electronics Review - 1

Voltage – put it in terms that a 6th grader could understand

“Pressure”
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Pressure on electric charge (e-). Units are in Volts
Urges charge to ‘flow’
Measured relative to a reference pressure level

An “across” quantity – we measure it across two points (Don’t say ‘the
voltage through…’)
A
B
R1
“High” pressure
Voltage source acts like a
pump
+
R2
Vi
C
“Low” pressure
R3
D
Ground is often taken as the
low pressure point, but any
point could be taken as
‘ground’
ex. VAD = Vi = -VDA
Basic Electronics Review - 2
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Current – put it in terms that a 6th grader could understand
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“Flow”
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Flow of electric charge (e-). Units are in Amps
The response of charge to applied voltage
Need a complete circuit for current to flow

A “through” quantity – we measure it through an element
A
B
R1
“High” pressure
+
R2
Vi
I
“Low” pressure
C
R3
D
We will assume
‘conventional’ current flow –
positive charges flow out of
the + terminal and return to
the - terminal
Basic Electronics Review - 3
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Resistor – put it in terms that a 6th grader could
understand
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“Flow restriction” (causes a pressure (voltage) drop across it), an
impedance
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Drinking a milkshake through a straw
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Small diameter straw – high resistance
 Causes large pressure drop
Large diameter straw – low resistance
 Causes small pressure drop
Units are in Ohms
Dissipates power in heat!
A
B
R1
“High” pressure
+
R2
Vi
C
“Low” pressure
R3
D
Basic Electronics Review - 4
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Ohm’s Law (know it cold!)
 V=I*R
 A relationship between current and voltage for a resistor


The slope of the V-I line
The voltage drop across a resistor is proportional to the current
through it
V
I
V,volts
R
R
I, Amps
R increasing
Basic Electronics Review - 5
Original Circuit

Equivalent Circuit
A
A
R1
Vi
+
+
R2
Vi
Req
R3
D
D
Basic Electronics Review - 6

Power (units are in Watts)
= I2R = (V/R)2R = V2/R
 P = I2R = I2(V/I) = IV
P

Note: can calculate the
power required for any
circuit by measuring I and
V and taking their product
Any circuit
A
I
B
R1
+
R2
Vi
C
R3
D
Capacitor

Capacitor– put it in terms that a 6th grader could
understand

“Accumulator”, water tank

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Pressure storage. Stores energy in an electric field
Voltage across the leads takes time to build up. Units of
capacitance are Farads
Q  CV
V
+
-
V  A sin( t )  A sin( 2ft )
dV
 d ( A sin( 2ft ) 
iC
 C
 2fCA cos( 2ft )

dt
dt


dQ
dV
iC
dt
dt
1
V   idt
C
1
E  CV 2
2
Inductor

Inductor – put it in terms that a 6th grader could
understand

“Flywheel, merry-go-round”
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An inertia. Stores energy in a magnetic field
Tries to oppose changes in current flow. Units of inductance are
Henrys
V
+
-
i
i  A sin( t )  A sin( 2ft )
di
V L
dt
1
i   Vdt
L
1 2
E  Li
2
di
 d ( A sin( 2ft ) 
V  L  L
 2fLA cos( 2ft )

dt
dt


The Voltage Divider
Consider two resistances in series
 What is VA in terms of

 Vi,
R1 and R2
Vi
+
R1
A
VA
R2
D
So what? Why is this important?

Voltage divider effect occurs whenever one circuit is
connected to another

Voltage dividers can be used to set a voltage level
somewhere between a given supply voltage and ground

If significant current is desired, it is better to use a power supply
or voltage regulator