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Vincent's Electrical Crashcourse WIP
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Electrical Crash Course

2018 Summer

Revision: 0.1

Vincent Yuan

yuanv@alumni.ubc.ca


Motivation        3

How to Use        4

Course Number Reference        5

K.1 Electrical Prototyping        6

K.1.1 - Wires        6

Wire Gauges        6

Solid v. Stranded        7

Wire Color        7

K.1.2 - Building Circuits        8

Breadboards        8

Prototyping Boards        8

Terminal Blocks        9

K.1.3 - Bench Tools        10

Multimeters        10

Function Generators        11

Oscilloscopes        11

K.1.4 - Circuit Simulators/Software        12

K.1.5 - Sourcing Components        12

K.2 Electrical Components and Circuit Theory        13

K.2.1 - RLC        13

K.2.2 - Antennas        13

K.2.3 - BJTs, MOSFETS and Relays        13

K.2.4 - Voltage Regulators        13

K.2.5 - Amplifiers        13

K.2.5 - Connectors        13

K.3 Amateur (Practical) Control Systems        14

K.3.1 - Pulse Width Modulation (PWM)        14

K.4 Common Circuits Reference        15

K.4.1 - H-Bridges        15

K.4.2 - Amplifier Circuits        15

Inverted        15

Non-Inverted        15

K.5 Analogue/Digital Interface        16

K.5.1 - Analogue Digital / Digital Analogue Converters (ADDC)        16

K.5.1 - Analogue Digital / Digital Analogue Converters (ADDC)        16

Projects and Tutorials        17

P.1 - Designing a blinking LED Light Circuit        17

P.2 - Triggering Relays, Circuit Protection and Power Distribution        17

P.3 - Reading Radio Signals and Controlling Motors        17

References and Further Reading        18

Appendix        19


How to Use

In most cases the information is provided and chosen by 20/80 principle. It is the 20% of knowledge that you will use 80% of the time. It will not be deep with theory, rather a pointer for you to know what to google next to solve your problem. Or you can think of it as information that will allow you to carry out small talk in the electronics shop.

In most cases, there are always exceptions for generalizations I make. If you decide that you do need something specific and it is not mentioned, that does not mean it doesn’t exist. Most things you imagine should exist, will exist, it’s just a matter of finding it. (This is in respecting to sourcing parts or chosing designs). And in any case where something you are looking for lands outside of the 20% common knowledge, you should probably think about why.

This document will be split up into two main components:

1. Knowledge, information, and where to find more

2. Projects and hands on tutorials.

        For the knowledge components, it is mostly used for reference. It is also information I use very commonly myself. This section would hold most of the 20/80 generalized knowledge that I think are important.  Information that I consider from this section will be labeled and numbered with ‘k’. Eg. (k.1 - Electrical Prototyping).

        For the projects sections, they will include references to sections from the knowledge section that you will need to complete the project. It will also include skills you would get to practice and learn from. Projects will be labeled and numbered with ‘p’. Eg. (p.1 - Flashing LED)

        In both the Knowledge Section and the Projects section, I will do my best to cross reference the relevant sections.


Course Number Reference

        Below covers a list of courses I can remember off the top of my head that covers similar topics in reference to the different sections:

Course Number

Course Name

Sections


K.1 Electrical Prototyping

K.1.1 - Wires

Wire Gauges

        Like recognizing fasteners and threads, learning constraints, wire gauge is something that is important when you are designing for specific safety factors. Wire gauge is often denoted as AWG (American Wire Gauge). Key notes on AWG:

        In most cases, the wires you use will be copper. Since we generally are choosing wire gauge based on the required current carrying capacity, below is a table for quick reference of common wire gauges you would be using:

Current(A)

472A

333A

235A

117A

83A

58.5A

41A

29A

20A

14A

AWG(No.)

8

10

12

16

18

20

22

24

26

28

Diameter

(mm/in)

3.264/

0.12885

2.588/

0.1019

2.053/

0.0808

1.291/

0.0508

1.024/

0.0403

0.812/

0.0320

0.644/

0.0253

0.511/

0.0201

0.405/

0.0159

0.321/

0.0126

* The current in reference on this table is based off of Preece Fusing Current for ~10s. Basically it’s the amount of current you will need to apply for 10 seconds to melt your wire. So chose wisely.


Solid v. Stranded

        Should I chose solid core or threaded/stranded wire? Here are rules of thumb:

Wire Color

        We don’t like to segregate, but choosing your colors correctly will help you with understanding circuits that you have built. In general we chose the following for DC circuits:

Vcc/Positive Terminal/+

Gnd/Ground/Negative Terminal/-

Signal/S

Red

Black/Blue

White/Yellow


K.1.2 - Building Circuits

        We will need ways to connect wires to components most of the time. Examples include breadboards, prototyping boards, terminal blocks...etc.

Breadboards

        Breadboards are friends, not food. As you can see below, there are conductors that connect the pins in a breadboard.

[3]

Good practice is always to connect your power input to the power rails and then connect the power rails onto the other components on your system. This is because when you start having circuits that you would need to clean up signals with, or isolate noise from, it will be easier. This will be explained in later sections. Breadboards are desirable to test with because the pitch of the pins match most IC chips you use.

Prototyping Boards

        In general, to move to something more permanent without designing your own PCB, we use prototyping boards, they look like:

 

        As can be observed, the layout is very similar most of the time, which makes transfering your prototypes easier.

Terminal Blocks

        Now, in the case where you have chosen to distribute a casual few hundred watts to your circuits, you might have chosen some pretty thick wire. You would notice that breadboards and prototyping boards are quite limited in their ability to accomodate big wire gauges. In those cases, we would need other methods of connecting things. Most commonly, we will chose to use terminal blocks and crimps.

These are terminal blocks:

These are crimps:

The connection (ha.) should be obvious. The terminal blocks on the left and middle will be able to use the crimps with circular connectors. The terminal block on the right would not need crimp connectors on the wires to be able to connect them.

The biggest difference between the two types of terminal blocks would be that for the terminal blocks that require crimp connectors, you are able to stack multiple wires together. Contrary, the terminal block on the right would only be able to hold a single wire on either end of the connector.


K.1.3 - Bench Tools

Multimeters

        Multimeters are your friend. You have probably seen these:

There are bench multimeters and handheld multimeters: In general they are the same, only difference would be size, and power rating they may be able to handle. Multimeters are also amongst the simpler devices to use. However, there are two things that think requires comments on.

First is the 4 connections to choose from on the multimeter:

        From left to right:

        Second, one of the most useful functions of the multimeter that I don’t think people are using enough is the diode/short circuit test. Or as I like to call it, the beep beep test. On all multimeters you will find a mode with the diode symbol. It will be your friend to make sure that you have connected things correctly.

Function Generators

        This is a function generator:

        As it’s name suggests it generates oscillatory signals. Using it is straightforward, so this will be something to learn during tutorials. However below are a few use cases for this:

Just the usual stuff.

Oscilloscopes

        This is the inverse function generator:

        You will use this to observe AC signals. Good for observing specific behaviors that you are/are not looking for, like, damped signals, delays, decays...etc.  You probably learned how to use this in first year physics, so like the other devices, I won’t go in detail.

K.1.4 - Circuit Simulators/Software

        There are a lot of circuit simulators that exist right now. That includes SPICE (Simulation Program Integrated Circuits Especially) programs, layout programs or mixtures of both for large and small circuits:

K.1.5 - Sourcing Components

        The best place for you to find components would be Digikey. Some notes:

        In other cases where you are looking for more general hobby components I would suggest:

K.2 Electrical Components and Circuit Theory

K.2.1 - RLC

Resistors, Inductors and Capacitors

        Resistors, Inductors and Capacitors are the fundamental components of circuit theory. Here are what they look like, and what they do:

Resistor

Inductor

Capacitor

Picture

Symbol (Std./Int.)

Common Range (Unit)

0-Mega (Ohms)

1 Micro - 20 (Henrys)

1 Pico - 1 Milli (Farad)

Equation

What happens

Resistors prevent current flow.

Inductors prevent change in current.

Capacitors prevent change in voltage.

Mechanical Equivalent

Damper

Spring

Mass


K.2.2- Solving Circuits

        Fundamental circuit solving theory is build around two laws:

  1. Voltage Law: Voltage difference along a loop is equal to zero.  
  2. Current Law: Total current travelling into a node (intersection of wires) is going to be equal to current exiting the node.

        As conservation of energy is true no matter what system you are looking at, remember that  is your friend for that. Where P is power in units of Watts, V is voltage in Volts and I is current in Amperes.

        IMPORTANT: Current is defined as the flow of positive charge! What does that mean? It means that electrons move in the opposite direction to the arrows you draw on your circuit.

K.2.3 - Antennas

        The governing high level concept for antennas and wireless energy transmission would be based off of Friis Transmission Formula:

        


There are a few types of common antennas:


K.2.3 -Transistors and Relays

        Transistors and Relays are the controllable valves of electrical circuits.

Transistors

BJTs (Bipolar Junction Transistors) and FETs (Field Effective Transistors) are the two major types of transistors. MOSFETs (Metal-oxide Semiconductor Field Effective Transistors) are one of the more common types of FETs you will see. Most commonly they can be differentiated by their look:

The one on the left is what a FET would usually look like, and the one on the right is representative of the most common packaging for transistors. As can be seen, they each have 3 pins:

FETs:

        BJTs:

        The biggest difference between FETs and BJTs are that one is unipolar and the other, as the name suggests, is bipolar. Polarity refers to the carriers, more specifically holes, denoted p, and electrons, denoted n. In other words, during operation FETs will only have holes moving or electrons moving. On the other hand, during operation BJTs will have both the holes and the electrons moving. Knowing that there may be a difference in majority carriers, there are two sub-types for each type of transistors. BJTs are split into NPN and PNP transistors, while FETs are split into N-Type and P-Type.

        For both these devices, you would control the flow of current by adjusting your voltage on the regulating terminal. (Gate for FETs, Base for BJTs).  


BJTs in Detail

        This picture below is a depiction of the the material construction inside a BJT, specifically an NPN BJT.

        The way to observe and understand what’s happening is as follows:

  1. First recognize that there is an external potential gradient denoted by Vcb and Vbe. This means that all the positive charge (holes) is aggregated on the right side of the diagram. What this means is that electrical current will prefer to flow in the counter-clockwise direction, whilst the traditional electron is moving the the clockwise direction as denoted in the diagram.
  2. However, it is important to note that there is the P-junction filled with holes dividing the circuit up. If Vbe did not exist, there would be no potential gradient across the NP junction on the left side of the device. As a result the white arrow of holes would not exist. Since Vbe does exist, holes are able to travel from the P junction to the N junction on the left.
  3. In attempt to balance out the system, electrons would move in the opposite direction from the N junction on the left to the P junction completing the flow of the circuit.

FETs in Detail

        Below is a cross-sectional diagram of a N-MOSFET.

        

For FETs, the operational steps are as follows:

  1. A voltage is applied to the Gate, creating a gradient that forces positive particles (holes) to move into the depletion region.
  2. To balance out the change, the electrons will move towards the depletion region right below the gate.
  3. Electrons can now freely flow between the source and the drain.

Relays

        The main difference between relays and transistors using the valve analogy is that relays is toggling between 2 different sources, while transistors open and close. Traditionally relays were made with little electromagnets that toggle the connection like the following:

        As can be seen, a pair of connections are needed to supply power to the coil, and a trio of connections are being toggled. The trio is usually labeled NC, C and NO for Normally Closed, Common and Normally Open. The context for normality refers to the state when the coils are not being powered. Therefore as can be observed, when you power the coil, the connection between Common and Normally Open are now closed, completing the circuit.

        This is a really good feature of the device for safety circuits because when power to the coil is disconnected, the circuit will return into its natural state, disconnecting Common and Normally Open.

        As technology has progressed, relays have also been recreated with semiconductor materials. These are commonly referred to as solid state relays as opposed to the mechanical relays discussed above.

Common packaging for mechanical relays can be seen in the images above. The three on the left are mechanical relays, while the one on the far right is a solid state relay. The packaging of the first relay from the left is of automotive standards, hence why you will find some weird numbers for the terminal labels, as well as the flat metal terminals that connect to crimps.

K.2.4 - Voltage Regulators

K.2.5 - Amplifiers

K.2.5 - Connectors

K.2.6 - Special Applications

Flyback diode

Coupling and decoupling capacitors  

Motors

DC Motors

Stepper Motors

Servo Motors


All about Sensors

Terminology

Accuracy and Precision

You might find this common sense, but I want to make sure we understand the difference between accuracy and precision. Being accurate refers to how close our measured value to is to “the truth”. Precision on the other is all about the consistency of data we are receiving.

This distinction is important because with Sensor Fusion, we are extracting higher accuracy by combining multiple sensors measuring the same thing. In the process of doing so, we have to account for the precision of our sensors. We cannot simply assume the accuracy of a sensor even if it was precise, hence the need for calibration on all the sensors we use. For sensors, precision is static relative to the operating point you chose. In other words precision is not something we can improve without making a new sensor. On the other hand, accuracy is something that the end stream engineers like us can improve on. Improving accuracy would require more sophisticated techniques detailed in the other sections.

Types of Sensors

Inertial Measurement Unit

Accelerometers

Gyroscopes

Compass

Sensor Fusion

        Sensor fusion is a huge topic with various methods.


Amateur (Practical) Control Systems

Pulse Width Modulation (PWM)

K.4.2 - Bang Bang Controllers


K.5 Common Circuits Reference

K.5.1 - H-Bridges

K.5.2 - Amplifier Circuits

Inverted

Non-Inverted

K.6 Troubleshooting and Fixing Circuits

K.6.1 - Symptoms, and Fixes


K.7 Analogue/Digital Interface

K.7.1 - Analogue Digital / Digital Analogue Converters (ADDC)

K.7.2 - Analogue Digital / Digital Analogue Converters (ADDC)

K.8 Enclosures

K.8.1 - O-rings

https://microgroup.com/wp-content/uploads/2015/01/Surface-Finish.pdf

K.8.2 - Cable Glands

K.8.3 - Cable Connectors


Projects and Tutorials

P.1 - Designing a blinking LED Light Circuit

Purpose:

This purpose of this project is for people to be familiar with the basic hands on prototyping skills. This includes choosing components, clean wiring on breadboards, soldering and some very basic circuits.

Reference Sections:

Components Needed:

Tools Needed:

Process:

P.2 - Triggering Relays, Circuit Protection and Power Distribution

P.3 - Reading Radio Signals and Controlling Motors and coiling transformers


References and Further Reading

K.1.1 - American Wire Gauge - https://en.wikipedia.org/wiki/American_wire_gauge 

K.4.1 - PWM - https://www.arduino.cc/en/Tutorial/PWM 


Appendix


Motivation

        The purpose of this document is to provide the lesson plans/information that can be reused for teaching practical electrical engineering skills that I consider important for students on working on project teams. It is a collection of things I had wished I would’ve learned earlier in electrical engineering to be more productive working on projects.

        The main motivation for running this course is out of frustration of the lack of practical knowledge provided by the current electrical engineering curriculum. This has become evident to me through my attempts at finding a co-op job in second year and recruiting electrical engineering students for project teams. It has not necessarily been the case where theory was lacking, but rather the applications of the wealth of knowledge built up from courses that was lacking.

        I am in no position to criticise the current electrical curriculum as I have gone through long discussions with instructors around the current state of the UBC EECE curriculum. However a clear comparison between second year EECE students and students having gone through the Mech2 program will show you the difference in problem solving ability built up. Though this situation has since greatly improved through the improvement of the first year UBC APSC program.

        This course plan is most certainly not an exhaustive list of things I wish was taught, but it should be enough for any student to join a student team and understand the basics in contributing to a project that concerns the electrical engineering discipline.  It should also be noted that I am most certainly was not the most hard working student in school, my failed courses and low GPA is evidence. However, in most cases I see a lot of students having to struggle through courses simply because the topics are not of interest, the instructors are not helpful, or simply because they do not see if the potential of the knowledge they are obtaining.  

        There are a lot of things I personally have not learned, for example Altium or Solidworks Electrical...etc. These are all essential tools, and powerful tools that I think students should learn to use. Unfortunately since I do not not have enough knowledge in those subjects, I will not be able to discuss them. The hope is that revisions of this document by the more experienced can provide the necessary resources to gain knowledge on these subjects.

        All in all, I hope that this lesson plan can be used, improved over time by other leaders amongst the Engineering Design Team and UBC to provide new engineering students with the basic prototyping skills to create fun and interesting projects.

Vincent


[1] For people that want to try, wire gauge of n can be calculated via: [ n=-39log_92(d/0.005in)+36 ]. Where n is AWG, d is diameter in inches, and the log is base 92.

[2] https://en.wikipedia.org/wiki/American_wire_gauge

[3] https://learn.sparkfun.com/tutorials/how-to-use-a-breadboard