1. Basic Electronics Review
B. Furman
25AUG2015

2. Lecture Flow Today Items to focus on this week
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

3. Learning Objectives
Get prepared for Lab 1 and started on PortMaster build
Get started on the term project
Explain in simple terms what is meant by:
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

4. Mechatronics Concept Map
System to Control
Sensor
Signal Conditioning
Controller (Hardware & Software)
Power Interface
Actuator
User Interface
Power Source
BJ Furman 22JAN11
ME 106
ME 154
ME 157
ME 195
ME 120
ME 297A
ME 190
ME 187
ME 110
ME 136
ME 182
ME 189
INTEGRATION

5. Lab 1 – Intro to the Mechatronics Lab
Read and prepare
Take the pre-lab quiz before you start your lab session

6. PortMaster
Solder practice
Bit manipulation and port IO learning

7. HW 1 and Questionnaire When are they due?
Hard and softcopy for Questionnaire
Soft copy only for HW questions

8. Term Project Overview See the guideline:
Video sample of previous projects

9. Key Concepts 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.

10. Basic Electronics Review - 1
Voltage – put it in terms that a 6th grader could understand
“Pressure”
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…’)
Voltage source acts like a pump R1 R2 R3 Vi + A B C D
“High” pressure
Ground is often taken as the low pressure point, but any point could be taken as ‘ground’
ex. VAD = Vi = -VDA
“Low” pressure

11. Basic Electronics Review - 2
Current – put it in terms that a 6th grader could understand
“Flow”
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 R1 R2 R3 Vi + A B C D
We will assume ‘conventional’ current flow – positive charges flow out of the + terminal and return to the - terminal
“High” pressure I
“Low” pressure

12. Basic Electronics Review - 3
Resistor – put it in terms that a 6th grader could understand
“Flow restriction” (causes a pressure (voltage) drop across it), an impedance
Drinking a milkshake through a straw
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! R1 R2 R3 Vi + A B C D
“High” pressure
“Low” pressure

13. Basic Electronics Review - 4
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 R
V,volts
I, Amps R
R increasing

14. Basic Electronics Review - 5
Original Circuit
Equivalent Circuit A A R1 + + Vi R2 Vi
Req R3 D D

15. Basic Electronics Review - 6
Power (units are in Watts)
P = I2R = (V/R)2R = V2/R
P = I2R = I2(V/I) = IV
Note: can calculate the power required for any circuit by measuring I and V and taking their product R1 R2 R3 Vi + A B C D
Any circuit I

16. Capacitor
Capacitor– put it in terms that a 6th grader could understand
“Accumulator”, water tank
Pressure storage. Stores energy in an electric field
Voltage across the leads takes time to build up. Units of capacitance are Farads V + -

17. Inductor Inductor – put it in terms that a 6th grader could understand
“Flywheel, merry-go-round”
An inertia. Stores energy in a magnetic field
Tries to oppose changes in current flow. Units of inductance are Henrys V + - i

18. The Voltage Divider Consider two resistances in series
What is VA in terms of
Vi, R1 and R2 Vi + A D R2 R1 VA

19. 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