5 min read
Ohm’s law: calculate current without losing the circuit
Use voltage, current, and resistance together, with a worked 5 V example and the limits of the simple resistor model.
Electronics guides
Understand the circuit, one connection at a time.
Plain-language guides with worked examples, diagrams, and links to the underlying sources.
Follow the beginner roadmap · Get the printable circuit worksheet
5 min read
Voltage vs current: two different questions about a circuit
Learn what voltage and current measure, why a source voltage is not a current reading, and how to debug a simple loop.
5 min read
What ground means in a circuit diagram
Separate the 0 V circuit reference and return path from protective earth, with a low-voltage example and safety boundaries.
5 min read
Open vs closed circuits: trace the entire path
See why an open switch stops an ordinary DC load, why a closed path can still fail, and how to check a low-voltage loop.
5 min read
Series vs parallel resistors: follow nodes before formulas
Compare shared current with shared voltage using 1 kΩ and 2 kΩ examples, equivalent resistance, and a practical wiring check.
5 min read
How to read circuit diagrams by tracing nodes
Follow source, load, junctions, crossings, and labels in a schematic without confusing symbol placement with electrical connectivity.
5 min read
Capacitor charge and energy: what 100 µF at 5 V stores
Calculate capacitor charge and stored energy, distinguish them from RC charging time, and handle residual voltage safely.
5 min read
How breadboard connections really work
Trace the hidden five-hole strips, center trench, and possibly split power rails before debugging your first circuit.
5 min read
Choosing a resistor for an LED
Estimate LED series resistance from supply voltage, assumed forward voltage, and target current without treating the LED as an ohmic load.
5 min read
How to measure voltage and current safely
Place a voltmeter across two points and an ammeter in series with a branch; avoid the current-mode short across a supply.
5 min read
Resistor power ratings: calculate heat, then leave margin
Calculate resistor dissipation in watts, compare it with a data-sheet rating, and account for tolerance and temperature.
5 min read
LED not lighting? Trace the circuit before replacing it
Diagnose a dark LED by checking polarity, five-hole breadboard strips, rail breaks, the return path, and voltage across the parts.
5 min read
Resistor color codes: read four and five bands
Decode significant digits, multiplier, and tolerance on four- and five-band resistors, then verify the physical part with a meter.
5 min read
Pull-up resistors: give an open switch a defined input
Wire an active-low button input with a pull-up, calculate its closed-switch current, and check leakage and logic thresholds.
5 min read
Switch bounce: why one press can look like several edges
Understand contact bounce, distinguish it from a floating input, and compare hardware and software debounce strategies.
6 min read
Voltage-divider loading: why the output falls under load
Calculate a 5 V divider before and after a 10 kΩ load, including branch currents and the limits of using dividers as supplies.
6 min read
LED and switch circuit: build a repeatable series loop
Wire a low-voltage LED, 330 Ω resistor and switch in series; predict, measure and diagnose the open and closed states.
6 min read
Voltage divider circuit: build and check a 5 V midpoint
Connect two 10 kΩ resistors across 5 V, predict the unloaded 2.5 V midpoint, then measure and debug the result.