Background Knowledge Probe

Write a list of the electronics that you make use of on a regular basis.

• Who comes to mind as the designers of these?
• What parts, inside and outside the hood, were used to build each one? To use it?
• What have you done with any items that started to work less than optimally?

Example: A Single LED Circuit

An electrical circuit is a path in which electrons flow from source to ground. The source is usually measured in voltage (the force, expressed in volts) or current (the flow, expressed in amps). A resistor (expressed in ohms) controls the flow of this source.

When I water my garden from a rain barrel, a full barrel has more pressure than one that is almost empty. That full barrel is the equivalent of a higher voltage power source, for instance, one that is 240 volts. A barrel two-thirds of the way full may be more like a 120 volt power source, while a nearly empty rain barrel may be closer to a 5 volt power source.

If I have a spray nozzle hooked up to my rain barrel, I can often use a lever to increase or decrease the water’s flow. This is equivalent to the current of the power source. Some of my water hoses are 1/2″ thick, while some are 3/4″ thick. This is equivalent to bigger or smaller ohms of a resistor, respectively, since a thinner hose increases the resistance of the flow of water compared to the thicker hose.

As a side note, in electrical engineering, Ohm's Law provides a basic equation I=V/R. This states that current (I) is equal to voltage (V) divided by resistance (R). And as all Trekkies know from their days with Jean-Luc Picard, resistance is not futile, it’s essential! Beyond this, don’t worry if you are ready to put aside these particular details.

Schematics are commonly used to draw out the path used by the electronic components to complete a circuit.

As an example, the Fritzing image above is a schematic with three electronic components:

• a battery
• a resistor
• a light emitting diode (LED)

The lines between are not electronic components, but rather are some form of conductive material like a metal wire that is used to carry the current from component to component. In the schematic, a positive current leaves the 9 volt battery and passes through a 560 ohm resistor before connecting to the positive charge of a 10mm white LED. From there, it passes through the negatively charged leg of the LED to the ground connection of the 9 volt battery, completing the circuit. Only when this circuit is fully and properly completed and the battery has sufficient charge to dispatch a current will the LED turn on. (Schematics and breadboard diagrams in this book were primarily created using the open source program Fritzing.)^[1]

Schematics don’t tell us anything about how the circuit is actually built, and indeed the visuals for the different components needed are confusing artwork until their interpretation is provided. But with a little bit of practice, schematics become a unique conceptual information source. We can use design thinking and rapid prototyping to physically make the circuit using specific parts on hand or acquired to achieve something we value, even if it’s just good enough to help more than bother us.

Often times, when you look for a plan or pattern to use electronics to perform a certain task, instead of a schematic, you’ll find a physical diagram of the parts as demonstrated in the Fritzing image shown above. This diagram is based on someone’s layout choices using available components to actually implement the circuit drawn in the Fritzing schematic at the start of this example. In the physical diagram, we see electrical components connected using a solderless breadboard, a plastic board with conductive clips under groupings of plastic holes, thereby allowing the passage of current between components.

At the left of this particular diagram, a red wire brings the positive current of the battery to the lower red rail of the breadboard. Another red wire moves it from this rail to row J, column 59. Row H, column 59 then connects the current to one leg of a 470 ohm resistor, which carries that current, now under resistance, to row H, column 55. This brings the current to the positive charge of a 10mm white LED. Row E, column 55 is connected to the negatively charged leg of the LED, which then passes to row A, column 55 where it is connected to a black wire that carries the current to the upper blue rail on the breadboard. A black wire then brings the current to the ground connection of the 9 volt battery, completing the circuit.

As you move forward, you may find yourself exploring and evaluating a variety of online guides, resources, and examples and comparing them to what is shown in the book. (Indeed, take a deep dive through the many examples found at Adafruit Learning System, from which we draw many for this book, for an extraordinarily wide range of electronic systems, along with supporting code.) Sometimes you may find schematics. But more often you’ll find diagrams illustrating how someone or a group have put the circuit into practice. Know that diagrams may be rigid as they tend to focus on a specific task in a specific configuration in a specific environment that suits a specific cohort, community, or culture. Schematics, on the other hand, are found in more professional settings and as such can be applied to a greater range of applications. These schematics, after doing research to define the components illustrated using specific visualizations, will also prove very helpful for problem solving or rapid prototyping for all innovators, regardless of experience.

It may be helpful to think of schematics as standards used for many different applications, projects, and occupations. Schematic drawings are relevant for many users from electrical engineers to K-12 students. For example, circuits and schematics are part of the Next Generation Science Standards (NGSS) Energy Unit for elementary school students in grade 4.^[2]

Underneath the Hood of the Breadboard

A solderless breadboard is a plastic board used to create models or prototypes of an electric circuit. They’re solderless because you can easily push wires into the provided holes and later pull them out to move them into new configurations. They come in different shapes and sizes. The most commonly used “full sized” breadboard is 6 1/2″ long and 2 1/8″ wide.

Below, you’ll note several different images of a full sized breadboard. In the first image, you see the typical working view of the breadboard.

In the next image, we see the bottom side of a breadboard. The left half of the center image has the sticky covering revealed, while the right half has the protective covering installed. If the breadboard is moved around a table or desk, a protective covering remains on the underside of the breadboard (seen in the right half of the center breadboard). You can remove that covering to enable the breadboard to stick to a surface (seen in the left half of the center breadboard).

In the breadboard image below, we see the underside of a breadboard, but this time with the sticky tape fully removed. Breadboards typically come with rails along the edges, with conductive metal clips (two of which are shown at the very bottom of the image) installed so as to carry the flow of current along the extent of each rail.

If you compare this image of the breadboard metal clips to the image of the top side of a breadboard, you’ll note there’s a red colored rail and a blue colored rail on the upper part, and another red rail and blue rail on the lower part of the breadboard. The red rail is typically used to carry a positive source to a circuit or series of circuits, while the blue rail is typically used to carry the circuit or series of circuits to ground. The main part of the breadboard connects together groupings of five holes using 126 conductive metal clips.

Thus, column 1, row A is connected to rows B, C, D, and E of column 1 with one metal clip. Column 1, rows F, G, H, I, and J are interconnected with a second metal clip. Column 1, rows A, B, C, D, and E do NOT connect with column 1, rows F, G, H, I, and J by default. They will only interconnect if a wire or electronic component is plugged into one of the left holes of column 1 and also to one of the right holes of column 1, and is set to pass a current from one connection to the other.

Building Our First LED Circuit Using the Raspberry Pi Electronics Toolkit

In the previous example, a circuit was created using a 9V battery, as shown in both a schematic and a diagram. Throughout the rest of this book, we will typically not use a battery to power our electronics. Instead, we will use a small, single-board microcomputer called the Raspberry Pi as a power source. The Raspberry Pi actively used around the world both for initial design and ongoing application of networked information systems for use in the field. It connects to 120V (United States) or 240V (many other nations) electrical power from a wall outlet or other alternating current (AC) power source using the kit’s Micro USB cable. The Raspberry Pi converts this voltage into 5V and 3.3V power supplies that can be accessed using the General Purpose Input Output (GPIO) pins of a Raspberry Pi. These pins provide a hardware link between the Raspberry Pi computer and electronics from the outside world.

For our prototyping activities, we’ll use a 40-pin ribbon cable to extend the GPIO pins to our breadboard by way of an Adafruit Industries assembled Pi Cobbler breakout printed circuit board. This brings together the Raspberry Pi’s GPIO pins and the solderless breadboard, along with a label for each pin, using a single ribbon cable rather than 40 individual wires, to make “cobbling together” prototypes easier.

Exercise: Building and Testing an Electronics Prototyping Platform

The image above provides a diagram of the basic configuration of the Raspberry Pi, GPIO ribbon cable, Cobbler, and breadboard. It also includes a diagram of a basic circuit in which 5 volts of current pass through an electronic component called a resistor, then through an electronic component called an LED, before returning to ground, thereby completing the circuit.

In the above diagram, it is important to note that there are only four electronic components illustrated:

• An unidentified larger black square integrated circuit microprocessor on the Raspberry Pi
• An unidentified smaller black square integrated circuit microprocessor on the Raspberry Pi
• A 560 Ω resistor
• A three millimeter (3mm) white LED on the breadboard

This can also be used using two different schematics:

• First, a schematic illustrating the conceptual layout of how the electronic components and power/ground sources on the Raspberry Pi connect to the Cobbler.
• Second, a schematic demonstrating a conceptual layout of how, using the Cobbler, a 5V (volt) power source can be connected to a 560 Ω (ohm) resistor electronic component, then to the positive, anode, leg of a Light Emitting Diode (LED), then from the negative, cathode, leg of the LED to a ground source to complete the circuit, thereby creating a white light source.

Before moving on to the steps listed below, watch these video demonstrations for the hands-on process and description of parts.

Troubleshooting Essentials

Design thinking leads us from inspiration to ideation to iteration and back. Iterations are typically done through picture drawings, models, and with electric prototypes, often through the use of breadboards. Failure is common, and generally remains the norm, from iteration to iteration for an extended period.

To positively fail forward, our iterations are an opportunity for us to discover how our inspirations and ideations aren’t aligning with our past and current iteration prototype. Said another way, iterations help us see how one part, much, or all of our design ideation is falling short of good enough. This helps inspire better ideations and sometimes even new inspirations, ultimately leading to better iterations — at least for us within the given testing context.

Let me say this again: Trying and failing is not optional. It is the norm. The general alternative to failing forward is failing to improve.

Accepting failure as a normal, active, ongoing part of what we do leads us to failing forward in ways that facilitate growth and betterment of ourselves, and when done across functional diversities and community cultural wealth, the betterment of others as well. In so doing, we foster a high performing community of practice.

So let’s assume the LED did not light up in the last exercise, or that it burned up in the last exercise, or that it won’t light up in the next exercise. Why not? What happened?

Humans and other more-than-human persons around us have a rich range of analog senses, such as sight, hearing, feeling, and smelling. These are a wonderful resource in the troubleshooting process. These analog senses provide a continuously variable physical quantity, such as the visible wavelengths of light. This stands in contrast to the digits 0 and 1 that typically represent the values of a physical quality provided by digital measurements.

Bringing our observations through those analog, continuously variable, senses into a process of critical thinking helps us create a plan for testing out a range of possibilities. Enacting that plan one step at a time helps us to continue the cycle of observation, thinking, planning, and acting. This is the heart and soul of inquiry-based learning as we collaborate in pairs and small groups through dialogue.

Throughout the remainder of the exercises in this book, and as you work through your own design activities putting your learning into practice, be sure to make extensive, preferably documented, use of these troubleshooting basics. It’s tempting to try it a few times and move on because troubleshooting the current exercises begins to become second nature. These experiences serve as a learning opportunity, but at the risk of having the learning become hidden knowledge that fails to fully help you as you encounter future problems.

Indeed, this is a reason why this book has been written using the Creative Commons Attribution-ShareAlike license. We hope you will add in annotations, page notes, and remixes for yourself and others to use as sources for their own design thinking projects. We hope the resulting inspirations, ideations, iterations, and failures support an advancing betterment of ourselves, those in our community of practice, and those we are serving through our creative works.

Do Something New!

For some, this is your first journey into electronic circuits. You’re Doing Something New through troubleshooting electronic circuits and failing forward!

For others, you may already have a lived experience with electronic circuits. This is not something new to you. But if you’re at all like me, some of this work has become rote, and the underlying terms, concepts, and principles hidden knowledge. For you, Doing Something New may be a work of re-remembering the codes to the electronic wheelhouse. And moving beyond, maybe its discovering some of the social influences that have shaped the non-neutral aspects of the otherwise strict laws of physics within.

For all, it’s likely at least some aspects of Collective Leadership, Community Inquiry, Action-Reflection, the Information Search Process, and Pair/Triplet Programming are new to you. Do Something New by incorporating one or two of these into your work this and every session individually and as part of your Community of Practice work.

Exercise: Two LED Circuits Using Different Ohm Resistors

In the last exercise, we used a 560 Ω resistor within our LED circuit. By providing a little resistance to the passage of an electric current, we help to stay within the optimum upper and lower current flow boundaries of a designated LED. While some LEDs have greater tolerances to non-optimal current passing through, others have less. And most electric power sources have some increases and decreases of current within a given voltage depending on conditions in the moment. Resistors are an important means of balancing this out.

For most of our work, a 560 Ω resistor will be just fine. But for a later integrated circuit, we’ll use a 10,000 Ω (typically specified as 10k Ω) resistor. Let’s see how a 3mm diffused white LED with a 560 Ω resistor compares to one with a 10k Ω resistor conceptually.

Each of the two LED circuits are designed as standalone circuits working in parallel. That is, if the metal wire from the 5V power source to the 560 Ω resistor were to somehow be cut, power would still flow over to the 10k Ω resistor – LED – ground circuit we’re about to build. Or vice versa if the wire to the 10k Ω resistor were cut and the 560 Ω resistor wire remained intact — the 560 Ω resistor – LED – ground circuit would remain live.

NOTE: Feel free to keep the Raspberry Pi plugged into the Raspberry Pi power supply. Also feel free to keep the first 3mm LED circuit live and the LED lit.

Before moving on to the steps, you are encouraged to do a “see once” viewing of the video in full.

Exercise: Comparing Differences in Resistance and Voltage

We’ve compared the brightness of LEDs using a 560 Ω resistor and a 10k Ω resistor. Now let’s test out the difference between a circuit using a 3.3 volt power source and a 560 Ω resistor and a circuit with our usual 5 volt power source.

Wrap Up

This is just a first glimpse at electronic circuits and some ways we can work hands-on in design and prototyping of new circuits. There’s much more to come as we proceed through the Orange Unit and beyond. For now, take a few minutes to do a quick comprehension check on some of the key circuit terms and concepts we’ve used so far.