Monthly Archives: September 2016

Fall 2016 – Week 7 Class Notes

We are almost to the halfway point of the semester! That means, we need to start thinking about next semester soon. I think I am going to see if we can renew with the current venue because it seems to be working for everyone. If anyone is having issues with the time or place (or anything else), please email me.

Computer Programming

First of all, the “Section 2” assignment is due next week! Pick your favorite homework problem or book activity from Part II of the book (chapters 6, 7, 8) and turn it in for an official grade.

This week we dove into the syntax of the JavaScript language, focusing on basic statements and also conditional statements (i.e., the “if” statement). The reading for this week is chapter 9 up through (and including) section 9.3.1. We are not doing any homework from the book this week, but you are encouraged to type out the programs from the chapter to solidify your knowledge. Next week we will finish chapter 9 and study looping mechanisms in code.

Note that the more you program, the better you will be at it. That is why I am encouraging you to do the examples, they will help you think about programming. I really like the fact that you all improvise on the assignments during class, because that helps your thinking, too!


UPDATE!!! In the chapter, there were some mistakes. (1) On page 79, in the middle of the page, it improperly suggests a ratio of 100ohms to 200ohms to get an 8V output. This should be 100ohms to 800ohms. (2) In the problem section, on #1, it should specify that the LEDs are red. (3) On questions #4 and #5, remember that the resistance of the load should be 10x the resistance of the parallel resistor from the voltage divider (see pg. 80).

Quizzes were handed back this week. The biggest problem, as I mentioned before, was understanding Kirchoff’s Voltage Law. Remember, the voltage drop between any two points on your circuit will be the same no matter what path you take! If you want to see the answer key, click the link below:

Quiz 1 Answer Key

This week we started talking about resistor circuit patterns. The reading is chapter 9. The most difficult circuit pattern we are covering is the pull-up resistor, but it will be important for our project next week. The reason it is called a pull-up resistor will become more evident in the next week.

Feel free to play with your circuit boxes throughout the week. One of my goals in providing you with your own take-home circuits is to make sure that you all are comfortable building circuits on your own. So feel free to experiment!

Don’t forget to download the latest version of the book.


This wee we moved from talking about the derivative to talking about differentials. If you can successfully make that pivot, you will be well on your way to understanding the finer points of Calculus! Chapter 10 is the reading, but I don’t yet have the problem set written. I will try to do that tonight or tomorrow. Calculus book is now available!

Fall 2016 – Week 6 Class Notes

Week 6 has just begun! Keep up the good work.

Computer Programming

We are now officially programming! I know it took us a while to get here, but I think that the preparation time was worthwhile. My goal was to hone your intuitions so that everything the computer does makes more sense as we learn about it. Remember – computers are stupid! They only do what you tell them! Everything they do has to be listed in the instructions or it doesn’t happen! Keeping those things in mind will propel you to really understanding computer programming.

Note that from here out even though the only official homework assignments are the problems in the back of the book, you will be a much better programmer if you type in each of the programs in each chapter. This experience will help you out a lot.

The second problem in the homework assignment may be beyond what is possible from where you are. However, think about the problem and make an attempt at it, even if you don’t get it all the way working.

Everyone is doing a good job on the computers during class. You all have a good ability to type, and a good habit of making the programs your own.


For most of the students, electronics is the most difficult class. I know that many of you are struggling, but take heart! This is not only your first year to take electronics, it is also my first year to teach it, so I am still finding out at what pace everybody learns at.

I know you are struggling, but I am more encouraged by what you do know than what you don’t yet know. Some of it will come with time. Because of that, I am taking this week as a review week. We will not go through the next chapter this week. Instead, take the time to re-read the previous two chapters (Series/Parallel and Diodes). See if you can re-work some of the problems. Don’t just take a break, use this as an opportunity to catch up.

Focus especially on Kirchoff’s Voltage Law. This is a pivotal (and somewhat unintuitive) law that is leveraged over and over in electronics. Being familiar with it and how to work problems with it will help you immensely!

Most people had difficulty with the quizzes this week. That’s okay, because even though you are especially familiar with the material from the last two weeks, most of you did very well on the material before that. However, let me point out that when doing anything, you should always show your work. I was able to give partial credit on several questions, but only if I could see what you were doing. If you just have a wrong answer, I can do nothing but mark it wrong. If you show me your thinking, I can at least give you credit for the parts of your thinking which are correct. Also, in complex problems, leaving it completely blank is unhelpful. The last question I gave partial credit to anyone who even started working on it. If you just labelled the resistors with their voltage drops without doing any calculations I gave some credit because I could verify that you had some understanding. I only labor on this point because it will help you in the long run.

The average value for the quiz was 28/40 (basically a low C). I had two students get 40/40. I had no one get less than half. That tells me that the work is difficult but doable, and that you all may be struggling, but are definitely making steady progress.

If you have any struggles or questions about the material, please email me!


Not much to say on the Calculus front – GO CALCULUS STUDENTS! Today we worked on solving real-world problems using Calculus, and generalizing our solutions developed in Calculus into basic formulas.

Next week, we will look at the derivative from a different perspective – the perspective of the differential. Chapter 9 this week!

Fall 2016 – Week 5 Class Notes

This was a tough but good week! I am happy with everyone’s progress on the material. Even if you think you are struggling, I think that everyone is actually doing pretty great. Keep up the good work!

Computer Programming

I am very impressed at how well everyone took to writing HTML this week. We started learning CSS and everybody is well on their way. The two most important concepts for CSS are (1) the idea of separating out content from presentation, and (2) using class and id attributes to specify special HTML elements on your page.

Note, however, that in class we put the stylesheet directly into our page for simplicity, but the book will have you store the stylesheet in a separate file, included by the “link” tag. These are basically equivalent, but the nice thing about the link tag is that if every page references the same stylesheet, you only have to change one file to change your whole website.

You all are doing great, and very soon we will be doing JavaScript.


Many of you noticed that this was a math-heavy chapter. It’s obvious I need to rework the chapter a bit to make it more obvious how to work the last problems. Below is how to work the now-infamous “Problem 13”, but first, a quick summary of the method. It is time-consuming, but hopefully each individual step makes sense. The steps are simple, but combining them is more tedious than difficult, once you know the trick. Also, just to make everyone feel better about it, one of my Calculus students said, “this week the math in Electronics was harder than it was for Calculus”. Anyway, take heart. Once you understand how these things work, it will be second nature to you. And that is more my goal – once doing this sort of calculation is second nature, then the stuff that we do next semester with audio circuits will be *much* easier to understand. When you can look at a circuit and can tear it apart in your mind, then understanding what people put in a schematic will be much easier even if you don’t bother with the actual calculations. Knowing that it *can* be calculated is just as important as everything else.

The key to it is realizing that anytime you come up with an “equivalent resistance”, you can (at least temporarily) replace that whole subcircuit with a single resistor with that resistance. This is especially helpful when you have combinations of series and parallel resistances. You basically use the series and parallel resistance formulas until you have a value for the resistance of the whole circuit, then use Ohm’s Law to find the current. Then you go back through and use the newly-found current to find voltages for each segment, breaking your circuit back apart into components as you go. So, here is the play-by-play for problem 13:

First we need to get the resistance for the whole circuit.
Starting with the positive terminal of our battery, we notice that the circuit immediately branches into two parallel lines. One line is R1, the other line is R2, R3, and R4. R2, R3, and R4 are all in series with each other, so the total resistance of those resistors is found by simply adding them together. We will replace them with a new resistor, which we will call R2-3-4, which will be 250 + 125 + 100 = 475 ohms.

So, now, our parallel resistance is between R1 (300 ohms) and R2-3-4 (475 ohms). Using Equation 7.2, the total resistance of this will be 1/((1/300) + (1/475)) = 183.87 ohms.
So, now, we can replace that whole shebang with a single resistor of 183.87 ohms. We will call this replacement resistor, R1-2-3-4.

Now, since we have replaced that whole subcircuit with a single resistor (R1-2-3-4), we now have a series circuit between R1-2-3-4 and R5. So this resistance is found simply by adding them together. So the total resistance will be R1-2-3-4 + R5 = 183.87 + 150 = 333.87 ohms.
Therefore, the total resistance for the circuit is 333.87 ohms.

Now we can find out how much current is passing through the whole circuit using Ohm’s Law.

I = V / R = 9 / 333.87 = 0.02696A

Okay, now, to solve for voltage, we can either start at the top or the bottom of the circuit. Let’s start at the top. So, we have this parallel resistance (R1-2-3-4) which is 183.87 ohms. 0.02696A is how much total current is flowing through it. Therefore, we can use Ohm’s Law to find out the voltage drop across this circuit:

V = I * R = 0.02696 * 183.87 = 4.957V

Now, to find out how much current is flowing across each individual element, we can also use Ohm’s Law.
For R1, the current isn’t known, but the voltage is (we just calculated the voltage drop across the whole parallel circuit). So, using Ohm’s Law, we find:

I = 4.957 / 300 = 0.01652A

So, the voltage drop across R1 is 4.957 and the current is 0.01652A.

Now, the other branch, R2-3-4, is 475 ohms. We can either calculate the current using Ohm’s Law, or just use Kirchoff’s Current Law. The Current Law says that the total coming out must be equal to the total coming in, so since we have 0.02696A coming in and 0.01652A going out one way, that means that there is 0.01044A going through the other pathway. Ohm’s Law would give us the same answer:

I = V / R = 4.957 / 475 = 0.01044A

Now that we have the current, note that the current going through each resistor will be the same (since they are in series), so, we can use Ohm’s Law to find the voltage drop in each:

For R2: V = I * R = 0.01044 * 250 = 2.61V

For R3: V = I * R = 0.01044 * 125 = 1.305V

For R4: V = I * R = 0.01044 * 100 = 1.044V

The total voltage drop matches the expected = 2.61 + 1.305 + 1.044 = 4.954V (a little off from rounding – we will use our original number, 4.957 for the rest).

Now, there are two different ways of finding the voltage drop across R5. We can either use Ohm’s Law (since we know the current (0.02696A) or we can use the fact that we just ate up 4.957V to find the remaining voltage.

Using Ohm’s Law: V = I * R = 0.02696 * 150 = 4.044V

Or, using the fact that it is a 9V battery, and that R5 is the only resistor left, we know that R5 must eat up the rest of the voltage in the circuit. So, since it started at 9V, and the parallel circuit ate up 4.957V, the voltage before the resistor is 9 – 4.957 = 4.043V. After the resistor we are back at the negative terminal, so the voltage is zero, so the voltage drop across this resistor is 4.043 – 0 = 4.043V. This only differs from our Ohm’s Law version due to rounding.

This week we are working with diodes. I didn’t give out any diodes because we were running short on time, but the text doesn’t require you to have one. I will try to give out regular diodes and zener diodes next week if you want to play around with them, though I may not currently have enough for everyone.

Next week we are going to go over some basic resistor circuit patterns, and then the next week we are going to build our first semi-useful device — a darkness sensor.

Don’t forget to download the new version of the book!


Today we covered and proved some of the basic rules of Calculus. I am not so interested in you all knowing the proofs as much as understanding the types of ways that rules are proven, because it helps you realize why we need special rules for different operations in Calculus.

You should memorize these rules: The power rule, the constant multiplier rule, the addition rule, and the exponent rule (i.e., all of the rules from the chapter). I will try to get the book updated tonight with exercises for Chapter 8 (if you download it and there are no exercises, that meant that I haven’t finished it yet).

Fall 2016 – Week 4 Class Notes

Here are the class notes for this week. Don’t forget to come back each week and check them out! You can always find them the next day after class.

Computer Programming

Today we started typing our own web pages. Unlike the summer program, where we had six whole weeks to concentrate on HTML, in this class we have reduced it to two – this week and next week. Therefore, read the chapter carefully, and be sure to do your assignments fully. Do your assignments early this week so that if you have any trouble getting it to work on your home computer, you can email me. Remember that you need to use a *text* editor (not a word processor) to do the assignments. Windows comes with Notepad, Macs come with TextEdit (though you usually have to click “Format” and then “Make Plain Text”), and Linux comes with gEdit or a similar program. The appendices in the back of the book have step-by-step instructions, but each operating system version is a little different, so please email me with any questions. If we get it right to start out with, it will make the whole class go better.

Today the section 1 graded assignment was due, but few actually did something for it. If you did not turn something in, be sure to do so next time. The next graded assignment is only three weeks away, so be sure to keep an eye out for which assignment problem you want to use.


Note – I updated the Electronics book, so download the latest copy.

Most of you were better about bringing your boxes! That made class work really smoothly. However, I noticed that some of you were getting bored with the material. However, understanding this stuff is important, because you will need to know it to understand the more fun material. This semester we can build some neat devices, and next semester we may be able to build audio amplifiers, but only if you take the time to learn the basic math behind the circuits.

We had some confusion over what chapter to read. Read chapter 7 this week! We kind of skipped over chapter 5. I sent home an updated syllabus. If you have not read chapter 6 yet, you need to read it and chapter 7. You can skip the chapter 6 homework if you have not done it yet.

Be sure when you come to class that either (a) you understand how to calculate current and voltage in a circuit that has serial and parallel resistances, or (b) you know what questions you want to ask about it, or specific problems you need help working. You may also ask questions by email. I am often on my computer, and often can reply relatively quickly. I understand that this is a boring part of electronics, but if you plow through it and learn it well then we can move to the fun stuff rather than be repeating it over and over again.

Also note – the schedule lists a quiz next week – be sure you know your stuff enough for the quiz! It will mostly focus on Ohm’s Law with a little on series and parallel resistances.

Also, just so everyone is clear – since this is not a math class, you can always use your calculators. It might be wise to bring one to class with you, too.


Note – I updated the Calculus book, so download the latest copy.

You guys are doing great – just read the next chapter in the book! We are already a week ahead of schedule, so we might slow down and do some stuff outside of Calculus for fun. If you have any subjects you are simply curious about, we can probably find math-oriented angles to look at in class.

Fall 2016 – Week 3 Class Notes

I hope you all enjoyed week 3 as much as I did! This week we really managed to start diving into each subject.

Computer Programming

In computer programming, we did the first computer simulation from chapter 5. As I mentioned, this is somewhat tangential to the actual class, but I find that people who know how the computer works form better intuitions about everything regarding programming. So that is where we are starting. Next week we will have the computer lab again and we will begin doing web pages, so come prepared to type!

The reading for this week is chapter 5. There is not much homework this week in the “Apply” section of the book, so what I want you to do is to bring me your papers that you filled out running the simulation.

Now, a lot of people get confused on the simulation, so I have a video to help you out:

Also, instead of drawing the worksheet yourself, you can download pre-drawn sheets from here:

So, you do need to answer the apply section, but the biggest part of your homework will be the simulation.

NEXT WEEK – your big homework assignment from section 1 is due. Remember, what we are doing is picking one homework activity that best represents your work in this class and turning it in for a grade. I would prefer this be printed out. Since there was very little programming in this class, some decent choices might be – (a) the technology essay, (b) for the younger students, writing out a full sentence in ASCII, or (c) doing a simulation (you might even pick out one of the “extra” simulations at the back of the book to try).


This is the first week we really got our hands dirty. We learned to use a breadboard and a multimeter, and this is essentially what we will use for the rest of the year.

I swapped out this weeks and next weeks’ chapters, so the chapter you should be reading is “Chapter 6: Constructing and Testing Circuits”. We will do series/parallel next week. This chapter has a lot of hands-on exercises with your breadboard.

Note that on some of the breadboards, the power rails only go half way across! This is indicated visually by a break in the red and blue lines. Also, a few of you had multimeters that were on the edge of being able to work or not. If those wind up being faulty, let me know.

Remember, everyone needs to bring their box each week! Otherwise you will wind up just watching the rest of us do electronics.


This week we started getting into derivatives! The derivative is when most people start to see the kind of inventive things that people can do with math. Remember that everything we did with derivatives stemmed from the simple definitions of lines and what it meant to be a line. All we did was to take the point-slope formula and trick it into giving us the answers we wanted.

Remember to download the latest version of the book!

I look forward to seeing everybody next week!