A course, not a reading list. Work top to bottom: each unit explains why the topic matters, sends you to specific chapters and videos with an instruction for each, and flags the thing those sources gloss over. Track A builds the electronics you need; Track B uses it to design a board. You cannot do the second without the first, which is why they are one path.
5 of 24 units built
Units A1–A5 are written and ready. The rest are in the syllabus so the whole shape is visible, and will be built in order — deliberately not padded with links nobody has checked yet. Every source is free, and every link here was fetched and verified before it shipped. ⚠️ A5 is the exception to 'in order': it was built ahead of its neighbours because impedance is a prerequisite for A9, B7 and B8, and nothing downstream is honest without it.
Track A — Electronics foundations
Twelve units from charge to instrumentation. The goal is not exam recall; it is being able to look at a circuit and reason about what it must be doing.
A1
Charge, voltage, current, resistance — and Ohm's law in practice
K ~90m
Everything downstream is this. Not because the equation is hard — you will have it memorised in a minute — but because the mental model underneath it decides whether the rest of the course feels like physics or like arithmetic. Most people who 'know Ohm's law' still cannot say what voltage physically is, and that gap shows up later as an inability to reason about why a circuit misbehaves.
After this you can
Say what voltage, current and resistance physically are, without reaching for the water analogy
Apply V = IR and rearrange it without thinking about it
Explain why current is the same everywhere in a series loop
Say what a voltage source and a current source each hold constant, and what that costs
The core section. Read for one thing: voltage is a difference BETWEEN two points, never a property of one point. If you finish able to explain why 'the voltage at this pin' is shorthand rather than a real statement, you have it.
Chapter 2 opens here. Work the numeric examples with a calculator rather than reading past them — the arithmetic is trivial and doing it is what fixes which variable goes where.
Watch for the distinction between a voltage source and a current source, and what each gives up to hold its output constant. Thevenin and Norton are introduced here — you do not need to be fluent in them yet, just meet them.
What to watch for
The water-in-a-pipe analogy is everywhere and it will get you through this unit, then quietly fail you around unit 5. Water pressure is scalar and local; voltage is a difference and it has a direction. When you hit AC and reactance, the analogy stops predicting anything. Use it as a crutch here, and be ready to drop it.
Circuit topology — series, parallel, dividers and Kirchhoff
K ~120m
This is where you stop reading a schematic as a picture and start reading it as a set of constraints. Almost every practical circuit you meet is a divider of some kind, and almost every debugging session is Kirchhoff's laws applied under stress. This unit is doing the work when you look at a board and think 'that node cannot be at that voltage.'
After this you can
Identify series and parallel sections by inspection, including when they are drawn to look otherwise
Calculate a voltage divider and state the loading condition that breaks it
Apply KVL and KCL to find an unknown in a circuit you have not seen
Explain why a divider is a bad way to power anything that draws real current
Covers dividers, series and parallel resistors and current dividers with real measurements. Watch the moment loading is demonstrated — seeing the output sag is more convincing than the algebra.
Read for the statement and one worked loop. Sign conventions will feel fussy — they are, and getting them wrong is the single most common source of a wrong answer.
Both laws demonstrated on real circuits. If the sign conventions did not land from the reading, this is where they usually click.
What to watch for
A voltage divider looks like a way to make a lower supply voltage. It is not, and this trips up nearly everyone once. The moment the thing you attach draws current, it becomes part of the divider and the output collapses. A divider is for making a reference that almost nothing loads — not for powering anything. If you remember one sentence from this unit, that is the one.
Voltage and current are what a circuit is doing. Power is what it costs, and heat is where that cost shows up. This is the first unit with a genuine hazard dimension: the difference between a design that works on the bench and one that browns, smells and fails in a sealed enclosure three weeks later is almost always a power calculation nobody did.
After this you can
Apply all three power relationships and pick the convenient one for the values you have
Read an absolute maximum rating correctly — and say why it is not an operating specification
Explain what derating is and why a part rated for your exact conditions is already a mistake
Identify where the heat in a circuit is actually being produced
Continue through chapter 2 to the power sections. Learn all three forms (P=VI, P=I²R, P=V²/R) — which one is convenient depends on which two quantities you happen to know, and swapping between them fluently saves real time.
The efficiency discussion is the useful half. Maximum power transfer is worth meeting but is a trap in practice — note that maximum power transfer and maximum efficiency are different operating points, and almost nothing you design wants the former.
What to watch for
An absolute maximum rating is the value at which the manufacturer stops promising the part survives — it is a cliff edge, not a target. Designing to it is designing to the failure point. The working rule is to leave real margin, typically running passives at half their rating or less, and more if the part lives somewhere hot or you care about its lifetime. ⚠️ The hazard here is genuine: an under-rated resistor or capacitor does not politely stop working, it gets hot, and electrolytics can vent.
Passives for real — markings, dielectrics and parasitics
K ~150m
Resistors, capacitors and inductors are the parts you will place by the hundred, and the gap between the textbook version and the real one is wider here than anywhere else in the course. A textbook capacitor has a capacitance. A real one has a capacitance that changes with applied voltage, temperature and age, plus a resistance and an inductance nobody drew. Every later unit that seems to be about layout — decoupling, power integrity, filtering — is really about these parasitics.
After this you can
Read a resistor's value from colour bands and from SMD markings
Say what an 0402 or 0805 package designation means and pick one sensibly
Choose between ceramic and electrolytic for a given job, with a reason
Explain ESR and ESL, and why a real capacitor stops behaving like a capacitor above some frequency
State why an MLCC's actual capacitance can be a fraction of its printed value in circuit
The physical model: charge stored in a field, and why the plate area and separation set the value. Read for the model, not the equations — the equations you can look up forever.
The mirror image of the previous section. The symmetry is worth noticing deliberately: a capacitor resists a change in voltage, an inductor resists a change in current. That pairing makes the AC unit much easier.
🔴 The most important item in this unit. Real ceramic capacitor selection — dielectric classes, DC bias derating, temperature coefficients, and impedance against frequency. This is the material that is missing from every textbook treatment and present in every real design review.
Skim. You want the idea that a conductor has resistance that depends on its dimensions — that is what makes a PCB trace a component rather than a wire, which Track B leans on heavily.
What to watch for
The DC bias effect is the one that catches people, and it is not subtle. A 10µF X5R ceramic capacitor operated near its rated voltage can deliver a small fraction of its printed capacitance — the marking is measured at almost zero volts. Nothing on the part or in most schematics warns you. When Phil's Lab reaches DC bias, slow down: this single effect explains a whole class of 'the design is right but the rail is noisy' problems.
This is the hinge the whole path turns on, and it is the one the existing decks never taught. Up to here a component has had a single number: a resistor is 10k, a capacitor is 100nF. From here every component has a value that depends on frequency, and that single idea is what decoupling, power integrity, filtering and controlled impedance are all made of. Reach Track B without it and the material there is not hard, it is unlearnable — you would be reading about matching a 50Ω trace with no model of what the 50Ω means. 🔴 It is also the longest unit in Track A, deliberately: it carries transients, AC, both reactances, impedance and filters, because splitting them leaves you stranded halfway across the gap.
After this you can
Explain why a capacitor resists a change in voltage and an inductor resists a change in current, and read an RC time constant off a circuit
State what reactance is, and why it falls with frequency for a capacitor and rises for an inductor
Say what impedance is and how it differs from both resistance and reactance
Apply Ohm's law in its AC form, and explain why the answer needs a phase as well as a magnitude
Explain why the same capacitor is an open circuit at DC and nearly a short at high frequency — and why that is the entire basis of decoupling
Recognise a low-pass and a high-pass filter from its topology and say roughly where its corner sits
The bridge out of DC, and the right place to start. Unit A4 gave you a capacitor as a physical object; this gives you what it does over time. Read for the exponential shape and the meaning of one time constant — not for the algebra. If you finish able to sketch the curve and say what τ = RC represents, that is the whole win.
The same material on a scope, which is worth far more than it sounds — the charge and discharge curves become a thing you have seen rather than a thing you were told. Watch for how the same circuit gives a completely different-looking result when the input changes faster than the time constant. That observation is reactance, arriving before it has a name.
Chapter 1 of the AC book. Read the whole opening section. The part to slow down on is RMS: it is not an average, it is the DC value that would deliver the same power, and that distinction is why 120 V AC and 120 V DC heat a resistor identically while their peaks differ by 70 V.
⚠️ This link lands on the resistor page, which is the chapter's opening contrast and only takes a minute — continue through the chapter into the inductor pages, which is the actual material. The target is X_L = 2πfL and the reason behind it: an inductor opposes change in current, so the faster you ask it to change, the harder it pushes back.
Same shape as the previous chapter, opposite behaviour — again, read past the opening resistor page. X_C = 1/(2πfC), and it falls as frequency rises. 🔴 Read this one deliberately rather than by symmetry: this is the single most load-bearing fact in the rest of the course, because it is why a decoupling capacitor works at all.
Where reactance and resistance combine into impedance. Watch for why they do not simply add: they are 90° apart, so it is a vector sum, not an arithmetic one. Admittance is the reciprocal view — meet it, but do not stall on it if it does not land; nothing later in this path depends on it.
Short and the most useful page in the unit. It is the consolidation: three quantities, what separates them, and which one you are actually holding in any given problem. If only one page from this unit survives in your memory, make it this one.
V = IZ — Ohm's law with impedance substituted for resistance, which is most of what you need AC theory for in practice. Watch for the phase relationship: the answer is a magnitude and an angle, and dropping the angle is exactly how people get plausible, wrong numbers.
The payoff. A filter is nothing more than a divider whose two halves respond differently to frequency, which you can now see directly. Read for low-pass versus high-pass by topology — which element sits in series and which shunts to ground — rather than memorising the corner-frequency formula.
What to watch for
🔴 The trap in this unit is treating reactance as a kind of resistance. It looks like one — it is in ohms, and it sits in Ohm's law where resistance used to — but a resistor turns energy into heat, and a reactance stores it and gives it back a quarter-cycle later. That is why resistance and reactance do not add arithmetically: they are 90° apart, so 30Ω of resistance and 40Ω of reactance make 50Ω of impedance, not 70Ω. ⚠️ The second trap is that this is exactly where the water-in-a-pipe analogy from unit A1 dies, as promised. Pressure has no phase. If you catch yourself reaching for it here, drop it — from this point on the useful picture is a rotating vector, not a flowing fluid.
Cards 40–46 were written for this unit: reactance, both reactance formulas, impedance as a vector sum, the DC-block/AC-pass rule, AC Ohm's law and filter topology. Before that, the deck had three adjacent cards — RC time constant, AC-versus-DC and RMS — and not one that tested reactance or impedance, which is the hole the s182 coverage report found.
A6
Diodes and rectification
Kplanned
One-way behaviour, forward drop, and the flyback diode that stops an inductive load destroying the thing switching it.
A7
Transistors as switches — BJT and MOSFET
Kplanned
Not amplifier theory. The switch case: what turns a MOSFET on, what R_DS(on) costs you in heat, and why gate drive matters more than people expect.
A8
Op-amps and comparators
Kplanned
🔴 A genuine hole — no op-amp card exists anywhere in the current decks. The two golden rules, the handful of configurations worth knowing, and why a comparator is not an op-amp.
A9
Power supplies, regulation and decoupling
Kplanned
Linear versus switching, dropout and LDOs, and the decoupling material the existing lesson already covers in depth.
A10
Grounding, noise and EMI
Kplanned
Ground is not a place, it is a return path. The unit that connects electronics to the board-level material in Track B.
A11
Test and measurement
KSplanned
Multimeter and oscilloscope — and specifically what each one cannot show you. Contains a Skill element that a card can never close.
A12
Safety and ESD
Rplanned
Mains voltage, stored charge, and damage you cannot see. Almost entirely Risk elements: identify the hazard AND its mitigation, which is not what a definition card tests.
Track B — PCB design
Twelve units following the order a real design actually happens in — which is not the order most tutorials present it. Stackup before placement, placement before routing, because each one constrains the next.
B1
What a board physically is
Kplanned
Laminate, copper weight, vias and surface finishes — the physical object the rest of the track manipulates.
B2
Stackup, and why it is decided first
Kplanned
Layer count is not about routing room. It sets your reference planes, and therefore your return paths and impedance, before you place a single part.
B3
Schematic capture, libraries and ERC
KSplanned
Currently one card in the whole deck. The unit where KiCad enters and where library discipline is either established or regretted.
B4
Footprints and land patterns
KSplanned
Where a design meets a real assembly line. Courtyards, mask-defined versus pad-defined, and the symbol-to-footprint mismatch that scraps a board.
B5
Placement — the decision everything inherits
KSplanned
🔴 One card exists today, against nine for fab outputs. Placement determines routing, return paths, thermal and decoupling. Taught by worked example and critique, not recall — the faded-worked-example mode.
B6
Return paths and reference planes
Kplanned
Current goes out and it comes back. Where it comes back is the single most useful thing to understand about a PCB.
B7
Power distribution and decoupling
Kplanned
The PDN as a system: regulator, planes, capacitors and package, and the impedance it presents across frequency.
B8
Routing — width, current, controlled impedance
KSplanned
Sizing a trace for current and for impedance, and knowing which of the two you are actually solving for.
B9
Signal integrity
Kplanned
When a trace stops being a wire and becomes a transmission line. Crosstalk, differential pairs, terminations.
B10
Thermal design
Kplanned
Getting heat out of a surface-mount part with no heatsink, using copper you already have.
B11
DFM and fabrication outputs
KSplanned
⚠️ Already the best-covered unit at nine cards. Needs no padding — it needs the rest of the track brought up to it.
B12
Design review and bring-up
KRSplanned
Reviewing a board before it is made, and powering one up without destroying it. Ends in a real artifact, so it can never be completed by a quiz.
The full reference shelf — textbooks, channels, tools and standards — lives on the electronics subject hub. This page is the course; that page is everything else worth having open.