Doug Nix

Category: Fun

  • Step-by-Step – Classes 4b & 4c

    Step-by-Step – Classes 4b & 4c

    From Capacitance to Resonance: Revisiting the Fundamentals

    Over the past couple of classes, we’ve been exploring two interconnected concepts in electronics: capacitance and resonance. For me, these aren’t new ideas—I first studied them at Sheridan College back in the 1980s, when oscilloscopes still had CRTs and breadboards came with point-to-point wiring. Even so, it has been rewarding to revisit these foundational topics with a fresh perspective and a few more decades of practical experience under my belt.

    Understanding Capacitance

    Capacitance is one of those elegant concepts that forms the backbone of modern electronics. A capacitor—two conductive plates separated by an insulating dielectric—resists changes in voltage by storing and releasing energy. It’s such a simple structure, but its impact on everything from timing circuits to power supplies can’t be overstated.

    Revisiting the theory reminded me just how differently capacitors behave in DC versus AC circuits. In DC, a capacitor charges up to the supply voltage and then effectively becomes an open circuit. In AC, though, the constantly changing voltage makes it look as though current flows straight through—even though electrons never actually cross the dielectric. This behaviour gives rise to capacitive reactance (XC), which decreases as frequency increases. That’s why capacitors block DC but pass high-frequency signals, making them indispensable in filters and coupling circuits.

    The unit of capacitance, the farad, is far too large for most real-world applications, which is why we use microfarads, nanofarads, and picofarads instead. Plate area, spacing, and dielectric material all shape a capacitor’s behaviour—details I once learned in a classroom, but now appreciate in a far deeper way after years of working with safety systems and control circuits.

    Revisiting Resonance

    Next came resonance—another familiar but fascinating topic. An inductor resists changes in current through its magnetic field, while a capacitor resists changes in voltage through its electric field. Put them together and, under the right conditions, they exchange energy back and forth in a kind of electrical echo.

    Resonance happens when the inductive reactance (XL) and capacitive reactance (XC) are equal and cancel each other out. At that frequency, the circuit oscillates like a perfectly tuned pendulum, trading energy between the capacitor’s electric field and the inductor’s magnetic field. That’s the essence of every tuned circuit—from early radio receivers to modern communication filters.

    One example that always comes to mind when talking about resonance is the Tacoma Narrows Bridge collapse of 1940. Although it wasn’t pure electrical resonance—it was aeroelastic flutter—the underlying principle was the same: energy reinforcing itself until a system fails. It’s a dramatic reminder of how resonance, in any form, can be both powerful and destructive if it’s not managed properly.

    Series and Parallel Resonance

    Reviewing series and parallel RLC circuits brought back memories of long lab sessions and breadboards filled with coils and capacitors. In a series circuit, resonance minimizes impedance, leaving only the resistance to limit current. In a parallel circuit, it does the opposite—impedance rises to a maximum.

    Those two behaviours form the basis of almost every practical filter: low-pass, high-pass, band-pass, or notch. Seeing the relationships between theory and application again reminded me why I fell in love with electronics in the first place. There’s something deeply satisfying about watching a sine wave sharpen or flatten on a scope exactly as the equations predict.

    The Quality Factor (Q) and Real-World Radios

    We also revisited the Q factor, which describes how “sharp” or selective a resonant circuit is. High-Q circuits have narrow bandwidth and greater selectivity, while low-Q circuits are broader and less discriminating.

    I built my first crystal radio as a preteen, so it was fun to see it come up again. With its single tuned circuit and diode detector, the crystal set has a very low Q—but it works. With nothing more than a coil of wire, a bit of crystal (or even a sugar cube and a sewing needle, if you’re improvising), and a pair of headphones, you can literally pull voices and music out of the air. Even now, I still find that magical.

    My Takeaway

    Revisiting capacitance and resonance after four decades reminded me how enduring the fundamentals really are. These aren’t just abstract properties—they’re the building blocks of everything from radios to robotics. Capacitors don’t merely “store charge”; they make stable, responsive, and selective systems possible. Resonant circuits don’t just cancel reactances; they allow us to shape and control the signals that carry our modern world.

    Coming back to these topics, I find myself both nostalgic and appreciative. The equations haven’t changed, but my understanding of their importance has deepened. It’s a reminder that no matter how advanced technology becomes, it all still rests on the same elegant principles we learned with coils, capacitors, and curiosity.

  • Step-by-Step – Class 4a

    Step-by-Step – Class 4a

    Sunday the 28th was our fourth class. We cover the basics of magnetism and inductance.

    Inductance: From High School Chalkboards to Everyday Engineering

    When I first studied inductance back in high school in the 1980s, it all felt a bit abstract. We were told that electricity and magnetism were linked in curious ways, that a simple wire could resist changes in current, and that this mysterious thing called “back EMF” always seemed to push back against whatever we tried to do. At the time, it felt like a trick of the math more than a tangible reality.

    Fast forward to today, and I see those same fundamentals in every transformer, motor, and circuit I encounter. The equations on the chalkboard have become the backbone of modern engineering practice.

    The Basics Haven’t Changed

    Inductance, at its core, is about resistance to change. Any conductor carrying current produces a magnetic field, and when that current changes, the magnetic field changes with it. Faraday showed us that a changing magnetic field induces a voltage, and Lenz’s law tells us that voltage will always oppose the change that created it. That’s why a conductor, whether straight or wound into a coil, pushes back against changes in current flow.

    In a classroom, this was demonstrated with the right-hand rule and magnetic field lines circling a wire. Winding that wire into a coil concentrated the flux, boosting its ability to oppose current changes. Back then it was a curious property. Today, I see it as nature’s built-in safety feature.

    Inductors in Action

    This week’s presentation walked through inductance in both DC and AC circuits. With DC, inductance delays the rise of current until the magnetic field stabilizes. With AC, the story is more dynamic: the magnetic field is always changing, always inducing a voltage that resists the flow. The result is what we call inductive reactance—an opposition that grows with frequency.

    This dual behaviour explains why inductors pass DC easily but can choke out higher-frequency signals. It’s the same principle that makes them indispensable in filters, power supplies, and countless control applications.

    From Inductors to Transformers

    Once coils are involved, it’s a short step to transformers. Here, changing currents in one coil induce voltages in another, enabling us to step voltages up or down, match impedances, or isolate circuits entirely.

    The elegance of the turns ratio—primary to secondary—never ceases to impress me. Whether it’s a massive utility transformer or a tiny toroidal inductor on a circuit board, the same rules apply: ratios matter, losses must be managed, and efficiency is king. Even after all these years, I find the beauty of this simple, reliable relationship remarkable.

    Enduring Lessons

    Looking back, what strikes me most is how little these fundamentals have changed. The names—Faraday, Henry, Lenz—still echo through the equations, but the applications have multiplied beyond what I could have imagined as a teenager.

    In high school, inductance was just another physics unit to get through before exams. Today, I see it as a quiet constant in my daily work—woven into motors, relays, solenoids, and transformers, underpinning so much of the technology we depend on.

    The fundamentals of inductance have aged better than we have: steady, dependable, and still as sharp as ever.

  • Step-by-Step – 3rd Class

    Step-by-Step – 3rd Class

    Understanding Ohm’s Law and Power

    A painting of Georg Simon Ohm.
    Georg Simon Ohm

    One of the cornerstones of electrical engineering and electronics is Ohm’s Law. It’s the simple yet powerful relationship that ties together voltage, current, and resistance—and it forms the basis for everything from circuit design to troubleshooting.

    The Basics: Ohm’s Law

    Ohm’s Law is expressed as:

    E = I × R

    Where:

    • E is voltage in volts,
    • I is current in amperes, and
    • R is resistance in ohms.

    This means that if you know any two of these values, you can calculate the third. The “Ohm’s Law Triangle” (or circle, depending on your preference) is a handy memory tool—cover the unknown quantity, and the relationship between the other two tells you how to solve for it.

    Putting It Into Practice

    The presentation walks through practical examples:

    • 12 V across 96 Ω → current is 0.125 A.
    • 1.5 A through 15 Ω → voltage is 22.5 V.
    • 550 mV across 0.1 A → resistance is 5.5 Ω.
    • 200 mA through 2.5 kΩ → voltage is 500 V.

    These worked problems highlight the importance of careful unit conversion—millivolts, milliamps, and kilohms need to be translated into base units to avoid errors.

    Series and Parallel Resistors

    A pile of random 1/8 W, 1/4 W and 1/2 W resistors of various constructions

    The presentation also digs into combining resistances:

    • Series circuits: resistances simply add together. Current is the same everywhere, but the voltage divides across each resistor.
    • Parallel circuits: resistances combine using reciprocals, and the total is always less than the smallest branch resistor. Voltage across each branch is the same, while current divides according to resistance.

    Worked examples show how to calculate total resistance, individual currents, and voltage drops in both series and parallel networks.

    Power in Electrical Circuits

    Beyond voltage and current, we need to understand power, which is the rate at which energy is converted into work. In electrical terms:

    P = E × I = E² / R = I² × R

    This is where the mnemonic PIE (Power = I × E) comes in handy. The unit of power is the watt, equal to one joule per second.

    Examples demonstrate that whether you start with voltage and resistance, or current and resistance, the result is the same: a 12 V source across a 50 Ω resistor dissipates 2.88 W of power, no matter which formula you use.

    Practical Considerations

    Resistors aren’t just about resistance—they also have power ratings. Exceeding the rated wattage leads to overheating and failure. As a general rule, always design with a 50–100% safety margin.

    The presentation also explores how power ratings are applied in series and parallel circuits, reinforcing the importance of checking each component’s limits before applying a load to a circuit.

    Wrapping Up

    The review questions at the end drive home the fundamentals:

    • Higher wattage bulbs consume energy faster.
    • Open circuits have no current.
    • Watts come from volts multiplied by amps.
    • Resistance equals voltage divided by current.

    Ohm’s Law and the concept of power are simple tools, but they’re the foundation of every circuit we build, test, or repair. Whether you’re a student learning the basics or a professional brushing up, getting comfortable with these relationships is essential.

  • Amateur Radio Codes of Conduct

    Amateur Radio Codes of Conduct

    Code of Ethics for Canadian Amateur Radio Operators

    Bill Wilson, VE3NR (SK)

    The thoughtful Radio Amateur is:

    Responsible–using courteous operating practice, complying with regulations and accepted technical standards;

    Progressive–striving to develop and improve operating and technical skills;

    Helpful–offering assistance, support and encouragement to other Amateurs, especially beginners; and

    Public Spirited–offering use of station, knowledge and skills as a public service whenever possible. 

    The Radio Amateur’s Code

    Paul M. Segal, W9EEA, in 1928 

    The Radio Amateur is

    CONSIDERATE…He/[She] never knowingly operates in such a way as to lessen the pleasure of others.

    LOYAL…He/[She] offers loyalty, encouragement and support to other amateurs, local clubs, and the IARU Radio Society in his/[her] country, through which Amateur Radio in his/[her] country is represented nationally and internationally.

    PROGRESSIVE…He/[She] keeps his/[her] station up to date. It is well-built and efficient. His/[Her] operating practice is above reproach.

    FRIENDLY…He/[She] operates slowly and patiently when requested; offers friendly advice and counsel to beginners; kind assistance, cooperation and consideration for the interests of others. These are the marks of the amateur spirit.

    BALANCED…Radio is a hobby, never interfering with duties owed to family, job, school or community.

    PATRIOTIC…His/[Her] station and skills are always ready for service to country and community. 

  • Step-by-Step – 2nd Class

    Step-by-Step – 2nd Class

    Today was the second class in the RAC Amateur Radio License course. We were studying Chapter Two of the Study Guide, Introduction to Electronics.

    This chapter lays the foundation for understanding basic electricity, beginning with the fundamental components of matter. Before delving into the technical theory, Al discussed the Amateur Radio Operator Code of Conduct. I decided that the two codes Al mentioned were important enough to warrant their own post, so you can find them here.

    We looked at atoms, their structure, and how the behaviour of electrons gives rise to electrical phenomena. From there, the discussion moved into conductors and insulators—why materials like copper and gold conduct electricity so well, while glass, rubber, and plastics resist it.

    Niels Bohr’s model of the atom (1913)

    Permittivity is a key idea in physics, especially in electromagnetism. It describes how a material reacts when an electric field is around. Understanding permittivity helps explain how electric fields work, as well as the functioning of capacitors, dielectrics, and electromagnetic waves.

    Permittivity, denoted by the symbol ε (epsilon), is essentially a measure of how well a material can allow electric fields to pass through it. It tells us how much the electric field inside the material is weakened compared to what it would be in a vacuum or open space. This property depends on the material’s makeup, structure, and physical state.

    Key ideas:

    1. Electric Permittivity (ε0): This is the permittivity of free space, often called epsilon naught. It’s a fundamental constant that describes how electric fields behave in a perfect vacuum. Its value is about 8.854 × 10-12 farads per meter (F/m). In a vacuum, the electric field moves without distortion or loss.
    2. Relative Permittivity (εr): Also known as the dielectric constant, this is simply the ratio of a material’s permittivity to that of free space. It’s dimensionless and tells us how well a material can store electrical energy in an electric field compared to a vacuum. Materials like glass, ceramics, and many plastics have high relative permittivity, making them very effective at energy storage.

    Insulators or insulating materials are those substances which will not allow the flow of electrons through them due to very low free electrons in them, and they have a low dielectric constant (Relative permittivity = εr).

    Examples: Porcelain insulators used in power transmission on distribution poles and towers, rubber, glass, plastic, wood, etc.

    Dielectrics or dielectric materials are substances similar to insulators but allow the flow of electrons through them when subjected to an external electric field, as they can be polarized. They can also be defined as having the ability to store charge (energy) through polarization, as in a capacitor. Additionally, they have a high dielectric constant. (Relative permittivity = εr).

    Examples: A common example of a dielectric is the electrically insulating material between the metallic plates of a capacitor, (such as mica, laminated paper). Other examples include air, ceramic, etc.

    • All dielectrics are insulators, but not all insulators are dielectrics.
    • Everything becomes a conductor at certain temperatures or electric fields due to breakdown, as every insulator has its limits to withstand a potential difference across the material.

    Key electrical concepts were introduced, including charge, current, voltage, and resistance. Al Penny VO1NO, our instructor, explained the coulomb as the standard unit of charge, the ampere as the rate of electron flow, and voltage as the “pressure” that pushes electrons through a conductor. Resistance and the factors that affect it—material type, length, diameter, and temperature—are also covered, along with the role of resistors and potentiometers in circuits.

    The class then explored magnetism as one of the four fundamental forces of nature, showing how magnetic fields, poles, and materials influence electrical behaviour.

    The four fundamental forces

    This naturally led to a discussion of direct current (DC), its sources, and the role of cells and batteries. Al explained the difference between primary (non-rechargeable) and secondary (rechargeable) cells, the chemistry behind common examples like zinc–carbon and lead–acid batteries, and how cells can be connected in series or parallel to change voltage or current capacity.

    By the end, the chapter tied together the essential elements of electricity—atomic theory, conductors and insulators, current, voltage, resistance, magnetism, and electrochemical cells—providing a solid grounding for anyone beginning their journey into radio and electronics.

    This was a review for me, as I have worked with electronics and electricity throughout my career. However, for anyone who doesn’t have a grounding in these subjects or feels like they need a refresher, this was a great place to start.

    If you are thinking about studying for an Amateur Radio Certificate, there are some excellent flashcard decks available for free on Ankiweb. One that I am using is the ISED basic amateur questions (2025) deck.

  • Step by step – 1st Class

    Step by step – 1st Class

    The first class for the Radio Amateurs of Canada (RAC) course was held tonight, September 18th, 2025.

    The opening class of the Amateur Radio course introduced the foundations of amateur radio, beginning with its international and national regulatory framework. The International Telecommunication Union (ITU) was presented as the UN agency that manages the global radio spectrum, divides the world into three regions for frequency allocations, and sets rules that all operators must follow.

    We learned how these global rules are applied in Canada through the Radiocommunication Act (1985) and the work of Innovation, Science and Economic Development Canada (ISED), the department that licenses amateur stations and enforces technical standards. The concept of the amateur radio service was explained as a non-commercial activity for self-training, intercommunication, and technical experimentation.

    The class also introduced the key organizations that support amateur radio:

    • International Amateur Radio Union (IARU) – representing radio amateurs globally since 1925, working to protect frequency allocations and expand opportunities for experimentation.
    • Radio Amateurs of Canada (RAC) – the national body representing Canadian amateurs, providing services like The Canadian Amateur magazine, a QSL bureau, liability insurance for clubs, youth education programs, and emergency communications support.
    • Canadian Amateur Radio Advisory Board (CARAB) – a consultative forum between RAC and ISED on regulatory issues.
    IARU Regions

    Finally, the session touched on practical topics: the different classes of amateur radio certificates (Basic and Advanced), exam formats and procedures, study skills, and resources to help new operators succeed. We were reminded that passing the exam not only grants a license but also a free introductory RAC membership.

    Amateur radio call sign prefixes by country.

    This first class set the stage by showing how amateur radio is much more than a hobby: it is a globally coordinated, nationally regulated service supported by dedicated organizations and volunteers, with strong ties to public service and technical innovation.

    So, onward to our second class on Sunday afternoon… I’d better get cranking on my homework!

  • Getting ready for school

    I signed up for ham radio license school today. Classes start on September 18th and run for 8 weeks. The course price is reasonable at CA $ 50, but then there is the study guide, which is another $45, etc. Anyway, this is the basic entry into the hobby, so I’m ready to go.

    I want to learn Morse Code too, but as they say, one step at a time. I’ve been shell-shocked by the cost of the gear needed for everything, starting with Morse keys. There are various types, starting with cheap and shitty at $15, up to Wow! That’s gorgeous! at > $300. If I buy a transceiver, then I can likely use it as a Morse Trainer. There are trainer keys that have a sounder built into the base, and then there are kits that can be built that even include a decoder so you can see just how bad your keying actually is.

    I found a reasonably priced key on Amazon, built by Putikeeg.

    Then I need a trainer before I get a transceiver. Here’s the one I’m thinking about.

    Anyway, I’m gonna wait on the CW1 (Morse) kit for now, as I want to get my Basic license in order first. Then my Advanced licence, and then my CW licence.

    Maybe I can buy a Silent Key’s2 station assets outright, for a single price. Yeah, that could work…

    Footnotes

    1. “CW” stands for “Continuous Wave” in ham-speak. It means that a continuous tone (700 Hz or so) is used to modulate the transmitter’s carrier wave when the key is pressed. Each key press creates the characteristic dots (dits) and dashes (dahs) of Morse Code. ↩︎
    2. A Silent Key is a ham radio operator who has died, and thus gone silent. ↩︎
  • Becoming a Ham Radio Operator

    Becoming a Ham Radio Operator

    This is the first entry in what I hope will be a series of entries about this new hobby that I’ve chosen to get into. I’ve been interested in radio since I built my first crystal radio kit when I was a kid, probably 8-10 years old, but I don’t remember exactly.

    I built a Remco 106 that closely resembled the one below. Sadly, I don’t have it anymore.

    Remco No. 106 Kit Crystal Radio

    I needed about a 50-foot [15 m] antenna, and access to a cold water pipe for a ground. I lived in an old house in Montréal then, which was nearly 110 feet front to back, and the upstairs hallway was more than long enough, so I was able to install the antenna inside.

    The downside with crystal radios is that they can only receive AM radio, so the sound quality is only as good as the station is broadcasting, and the quality of the headphones you’re using. Forget stereo. The headphones that came with the 106 were… meh.

    So now, many, many years later, I’ve decided to get into amateur radio. I have a friend who has had his licence since he was 10, and he’s 10 years older than me. He’s acting as my mentor in a way. He’s got a beautiful station, one I can’t even aspire to.

    So my first job is to get my licence. In Canada, if you score over 80 on the exam, you get wider access to the bands than if you don’t do so well on the exam. I recently took the practice exam and, going in cold (no studying at all), I scored a 74, so with a bit of work, I’ll be able to hit the magic number.

    I plan to attend the local Radio Amateur Club of Canada chapter meeting in September, and I’d like to have my licence before Christmas. I need to shake some time loose to study now…

    I’m also looking for some used equipment to get started with. My budget is limited, and I need everything—transceiver, power supply, antenna, mast, microphone, CW key.

    Once I get my regular licence, then I want to learn Morse Code so that I can add the CW certificate.

  • Canoes

    Solo canoeist in a green canoe on a mirror-calm lake. Mountains in the background.

    Paddling a canoe is one of my favourite ways to spend some time, alone or with someone.

    I first learned to paddle a canoe as a young Scout leader in the 1980’s in Guelph, Ontario. Another young leader, D’Arcy Grant, taught me the basics and helped me grow my skills over the years. His friendship and mentoring helped me gain the confidence to develop my skills and be ready to take our Troop out on the water.

    The rhythm of paddling, the quiet lapping of the water along the hull, the pace that allows for quiet observance of the environment around are all things that have brought me deep joy.

    I’ve paddled back-country rivers and lakes in Northern Ontario and urban and rural rivers in Southern Ontario. I’ve paddled solo and with friends. It all brings peace and joy to my heart.

    Predominantly blue image of a solo canoe and paddler on a calm lake with sunbeams coming through the trees.

    Movies

    Bill Mason is arguably one of Canada’s most extraordinary wilderness paddlers and documentary filmmakers. His movie, Song of the Paddle, speaks to the joy of exploring the Canadian wilderness by canoe. The National Film Board of Canada has made this movie available to stream for free. There are quite a few of his films available through the NFB site if you like this one, including instructional paddling movies.

    Books

    Some books in no particular order, all pretty old now that helped me get started:

    A red wood and canvas canoe with a single paddle, drawn up on a rocky shore with a mirror calm lake behind it, evergreen trees on the bank, and mist rising above the lake behind.