Electronics Tutorial

Table Of Contents

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Electricity and Simple DC Circuits
Start at the beginning. Each lesson introduces its symbols, repeats schematic-reading practice, gives worked examples, and ends with simple multiple-choice questions.

Electric Charge — Electrons, protons, the coulomb, and what charge means.
Electric Current — Charge moving through a circuit and the meaning of an ampere.
Voltage — What a volt actually means and where the name came from.
Resistance — What opposes current and why resistance is measured in ohms.
Ohm's Law — Putting voltage, current, and resistance together.
Measuring Voltage and Current — Using a meter correctly.
Series Circuits — One current path.
Parallel Circuits — More than one current path.
Electrical Power — Watts, power, and the horsepower reference.
Combination Series/Parallel Circuits — Simplifying a circuit one piece at a time.
Kirchhoff's Current Law — Current into and out of a node.
Kirchhoff's Voltage Law — Voltage rises and drops around a loop.
DC Review and Practice — A short practice test using everything so far.
The RC Time Constant — Adding capacitance and time to a DC circuit.

Alternating Current and AC Circuits
The same baby-step approach, beginning with what AC means before introducing reactance and impedance.

Alternating Current — AC — What changes direction and why we use AC.
Frequency and Hertz — Cycles, period, and the meaning of Hz.
A Little Trigonometry — Why Sine? — Enough trig to make the word “sine” friendly.
RMS Voltage and Current — What an AC voltage rating actually means.
Capacitive and Inductive Reactance — Frequency-dependent opposition.
Impedance — Resistance and reactance together.
AC Power and Power Factor — Watts, VA, phase, and power factor.

Logic — From Statements to Switches
Begin with logic in ordinary language, then bridge true/false statements to switches before introducing gates.

Logic Before Electronics — Statements, premises, conclusions, truth, and validity.
AND, OR, NOT — Logic in Ordinary Language — Including the important difference between OR and XOR.
If...Then — Implication — What “if A, then B” really means.
Truth Tables — Systematically listing every true/false combination.
Boolean Logic — True/False Becomes 1/0 — Turning logical language into algebra.
Statements Become Switches — Series = AND, parallel = OR, and the physical bridge to logic.
From Switches to Logic Gates — Begin with the buffer, then add the inversion bubble to make NOT.
AND, OR, and XOR Gate Symbols — Recognizing the three basic two-input gate shapes and their Boolean symbols.
Inversion Bubbles and Active-LOW Logic — What the small circles on inputs and outputs mean.
NAND, NOR, and XNOR Gates — Output inversion and the three complementary gates.
Equivalent Gates and De Morgan's Laws — Why bubbled gates can be redrawn without changing the logic.

Boolean Algebra — Calculating with Logic
Use algebraic rules to rewrite and simplify logic, while remembering that real gates still have electrical and timing limits.

From Symbolic Logic to Boolean Algebra — Symbolic logic, propositional calculus, Boolean algebra, fan-out, and propagation delay.
Boolean Laws and Identities — Identity, complement, distribution, absorption, and the rules used to manipulate logic expressions.
Simplifying Boolean Expressions — Reduce expressions and see why fewer operations can mean less hardware and delay.
Deriving De Morgan's Laws Without a Truth Table — Understand and prove the laws directly from language and Boolean algebra.
From Boolean Expressions to Gate Circuits — Translate equations into gate stages and back into physical switching logic.
Boolean Algebra Review and Practice — Mixed problems plus real-world fan-out, delay, and implementation questions.

State, Relays, and Memory
Move from logic that reacts only to present inputs into circuits that remember, beginning with relay notation and ending with clocked flip-flops.

State and Memory — When Logic Remembers — Combinational logic versus circuits whose previous state matters.
Reading Relay Schematics — Why relay coils and their contacts may be scattered around a drawing and how reference designators tie them together.
One Relay, Several Contacts — NO, NC, ganged contacts, and what “normal” means on a schematic.
Relay Seal-In and Holding Circuits — START, STOP, auxiliary contacts, feedback, and a physical example of memory.
The SR Latch — Electronic Set and Reset — Cross-coupled gates, Q, ~Q, and the hold state.
Latch vs. Flip-Flop — Level-sensitive latches versus edge-triggered flip-flops.
The D Flip-Flop and Timing — Clock edges, setup time, hold time, propagation delay, and metastability.
State and Memory Review — Mixed relay, latch, flip-flop, and timing questions.

Circuit Cookbook — Small Circuits That Do Useful Work
Use familiar components in simple real-world building blocks: passive networks, tube stages, solid-state circuits, and then combine those ideas into increasingly practical systems.

Circuit Cookbook Introduction — How to follow signal flow and recognize small circuits inside larger equipment.
Single-Stage Tube Amplifier — A common-cathode triode voltage amplifier and what each part does.
Voltage Divider — Two resistors creating a useful bias or reference voltage.
RC Low-Pass Filter — Reduce high-frequency noise and introduce low-frequency filtering.
RC High-Pass Filter and Speaker Crossover — Block DC/low frequencies and connect the idea to tweeter/woofer crossovers.
Diode Rectifier and Filter Capacitor — Turn isolated low-voltage AC into simple smoothed DC.
NPN Transistor as a Switch — Use a small control current to operate a heavier load.
Common-Emitter Transistor Amplifier — The solid-state cousin of the tube voltage-amplifier stage.
Emitter Follower — Analog Buffer — Near-unity voltage gain with useful current drive and isolation.
Transistor Relay Driver and Flyback Diode — Switch an inductive load safely and see the effect on release timing.
Op-Amp Voltage Follower — Unity-gain negative feedback used as a practical analog buffer.
Comparator — A Voltage Decision Circuit — Compare a sensor/input voltage with a reference and produce an ON/OFF decision.
Zener-Diode Voltage Regulator — Use a series resistor and zener diode to hold a small-load voltage near a chosen value.
Full-Wave Bridge Rectifier — Four diodes steer both halves of AC into one DC polarity.
Transformer-Isolated DC Power Supply — Combine transformer, bridge rectifier, filter capacitor, and load into one supply.
Simple Regulated DC Power Supply — Add a 7805 regulator after the rectifier and filter for a steady 5 V output.
Light-Controlled Transistor Switch — LDR divider, base resistor, transistor switch, and LED load working together.
Passive Audio Mixer — Combine two small audio signals through isolation resistors.
Audio Volume Control — Use a potentiometer as an adjustable audio voltage divider.
Simple Passive Tone Control — Use resistance and capacitance to make an adjustable treble-cut control.
Audio Op-Amp Buffer — Keep the passive mixer from being heavily loaded by the following circuit.
Op-Amp Summing Mixer — Turn the passive mixer idea into a defined-gain active summing amplifier.
Small Practical Audio Mixer — Put channel level controls, mixing resistors, an op-amp summer, and master volume together.

Capacitance, Timing, and Oscillators
Use capacitor charging and discharging first for delays, then for flashing, timing, oscillation, audio, ripple smoothing, and frequency response.

Variable RC Timer — Turn an RC time constant into an adjustable delay with a threshold detector.
LED Fade-Off — Watch stored capacitor charge produce a visible exponential decay.
Automatic Nightlight with Delay — Combine an LDR, RC delay, comparator, and transistor output.
Dual-LED Transistor Flasher — Two transistors and two capacitors form an astable multivibrator.
555 Timer One-Shot — Use the 555 in monostable mode for a predictable triggered delay.
555 Timer Metronome — Reconnect the 555 as an astable oscillator with adjustable beat rate.
Audio Tone Generator — Raise the oscillator frequency into the audible range.
Op-Amp Relaxation Oscillator — Expose the threshold, positive-feedback, and RC ideas behind oscillation.
Power-Supply Ripple and Filter Capacitor — See what the reservoir capacitor does between rectifier peaks.
RC Filters and Bode Plots — Connect high-pass and low-pass schematics with cutoff frequency and response graphs.

Inductor Circuits and Magnetic Energy
Begin with a visible electromagnet, then follow magnetic energy through relays, transients, flyback, and a boost converter.

Nail Electromagnet — Current through a coil creates a magnetic field strengthened by an iron core.
Relay Coil as an Electromagnet — Use magnetic force to move isolated electrical contacts.
Relay Buzzer — Let a relay interrupt its own coil current to create electromechanical oscillation.
RL Transient Response — Learn why inductor current rises gradually with time constant L/R.
Inductive Flyback in Depth — Follow stored magnetic energy when coil current is interrupted.
Simple Boost Converter — Deliberately redirect inductor turn-off energy to make a higher DC voltage.

LC Resonance and Frequency Selection
Bring capacitors and inductors together: energy exchange, resonance, oscillators, radio tuning, crossovers, and selective filters.

LC Energy Exchange — Watch energy trade between capacitor electric field and inductor magnetic field.
LC Resonance and Damped Oscillation — Introduce resonant frequency, ringing, damping, and Q.
LC Tank Oscillator — Add amplifier feedback to replace tank losses and sustain oscillation.
Passive AM Crystal Radio — Combine tuning, diode detection, and audio without a powered amplifier.
Two-Way Speaker Crossover — Split audio with a capacitor high-pass path and inductor low-pass path.
Band-Pass, Notch, and Q — Connect resonance with bandwidth and practical frequency selection.