ETR113 - DC & AC Fundamentals I:
Studies D.C. and A.C. circuits, basic electrical components, instruments, network theorems, and techniques used to predict, analyze and measure electrical quantities. Part I of II.
A solid start to a great semester with introductions and a little preview of the coming weeks! We began to look components of a circuit and build language around some of the basic concepts we will discover in this class. We also got to solder right out the gate and test the waters with tinning wires, through-hole components, and building a simple circuit. Everyone in class was given a red light emitting diode (LED), a 330 Ω (ohm) resistor, black and red #20 guage wire, and a small CR2032 battery. Each circuit built was slightly different and all brought about great points of discussion towards our capacity for understanding the fundamentals of circuit theory and analog components.
Carbon Film Resistor Datasheet
CR2032 Battery Datasheet
We spent the class going over the tools needed to succeed in class. We substituted the battery of our initial circuit to use a power supply (PSU), we looked at the voltage, current, and resistance functions on the digital multimeter (DMM), as well as breadboarding our circuits. Links to the DMM, Power Supply, and Breadboard resources are in the Introduction Section. We covered basics of electron flow, conductivity, and defined voltage, current, and resistance. As a result, we were asked to develop two circuits:
Using a breadboard, build your circuit from the previous class
Using the PSU as the battery, change values of your resistors and explore what occurs
Find I, V, and Ω
Using a breadboard, build a circuit with 3 LEDs, each obtaining optimal brightness using one 3V source
Find the best resistor value for each light
Record values of I, V, and Ω
Draw a schematic of your circuit
Basics of a Multimeter - Sparkfun
This class was dedicated to understanding the components in a simple circuit and how they interact. We reviewed our definitions of current, resistance, and voltage and applied them to the circuits we were constructing. Below is a schematic of the circuit we built without values. Using Ohm's Law we can begin to solve certain portions of the circuit. We also looked at the difference between series and parallel circuits. We also spent some of the class looking at Fritzing as a tool to document our schematics and breadboard examples.
We spent a portion of the class reviewing the material from the last class and going over any questions on the notes. We moved forward with adding some properties of parallel circuits, calculating total resistance and understanding this basic circuit as a current divider. We spent the remainder of the class building a schematic of the fan project, also looking towards a design that is functional. Many breadboarded their circuit and determined the correct component values and troubleshooted the process for building the complete, working circuit that includes:
An indicator LED
Connection to power supply
Meeting the requirements for your fan, voltage and amperage
User input (switch, knob...)
9.11 - Class Notes
This class period was devoted to troubleshooting our exhaust fans, building a working prototype on the breadboard, evaluzating component values, testing strategies for troubleshooting, and developing an enclosure. Below is a quick checklist of the requirements of this project:
Create a working schematic of your exhaust fan
Include LED, power, fan, user input with values
Build on protoboard to test your schematic
Start designing a simple enclosure/holder for your design
Begin soldering your circuit as needed...
More time and troubleshooting with solder exhaust fans. You will have a portion of the next class to finish this project. It should be complete by the end of class!
We spent the period talking about printed circuit board design (PCB) and how to make a simple one in Fritzing. We did some review on series and parallel circuits, while introducing voltage dividers. We will discuss this further in the upcoming class. We will also look at designing our first PCB! REMINDER: No class 10.09 and class will meet in the auditorium on 10.16 for a guest presenter.
We attended a guest speaker, Dr. Jennifer Chiu, talk about her research and journey in STEM education. We then spent the remainder of the class working through our projects and sharing our updates of the solder exhaust fans. We also used this class to begin looking through PCB design basics. We will fabricate our first PCB next class!
Fritzing to Inkscape: PCB Isolation
The goal of this class was to develop a simple, but highly constrained PCB using the laser cutter and chemical etching process. We used Fritzing to get started and cleaned up the PCB in Inkscape.
Design on a single-sided PCB
Powered by 9V Battery
Contain a power indicator light
Create a switch that has a 5V output using a voltage divider
Circuit must fit on 1" x 1" board
CR2032 3V Challenge:
Design on a single-sided PCB
Powered by a CR2032 Battery w holder
Contain an array or pattern of LED lights, min. 2x2
Create an on/off switch
Circuit must fit on 2"x 3" board
This class was devoted to building out our BOM for the project, finishing our EDA designs, and engraving our boards. We also looked at placing parts and drilling out our holes.
We begun our secondary PCB project focused on building an actual relay. We are looking at developing a mechanical switch that activates using an electromagnet and lower voltage. We exported our gerber files to prepare for the CNC mill.
Mechanical Switching Operation
Smaller than 2" x 3" footprint
We looked at how to calculate the electromagnetic field around an electromagnet. We built practice solenoids and tested their strength against voltage. We continued to mill PCB on the milling machine
The majority of the class was spent diving deeper into our PCB design and layout. The exmple is listed below. We used a 40 deg engraving V-bit for the isolation milling and a .9 mm drill for the holes.
Relay PCB Example - Fritzing
Today we worked on AC Basics and discussed the differences between AC and DC.
Final Project Guidelines:
Control the output of a 5mm LED
Have a minimum of 4 equal distinctions in brightness
Powered by 3V
Contain multiple test points for a DMM
Design the schematic and build on a breadboard minimum