CIRCUITS · ELECTRONICS · SIGNALS · PHYSICS · MATH

Learn electricity the way engineers work.

A deep, free learning tool for circuits, electronics, and the physics and math behind them. Every topic is a node on one tree. You light it by proving you understand it, then keep it lit.

Open in browser Download for Linux

Free. No account. Your progress stays on your device.

Center: charge, voltage, current. Outward: everything built on them.

01 · THE TREE

One tree for all of electricity.

Topics build from charge, voltage and current into circuit analysis and electronics. Every line between two nodes is a real prerequisite, so you always know why something is locked and what it leads to.

Dark

Not reachable yet. You can see it, and how far the subject goes.

Ready

Ready to learn. Every prerequisite is already lit.

Lit

Mastered: five right in a row without hints, each one harder than the last.

Review due

Lit topics come back for review after 1, 3, 7, 14 and 30 days. Miss twice in a row and it has to be lit again.

02 · REAL WORK

Design to spec, with real parts. The way professionals do it.

Design problems give you a requirement and a standard series to choose from. Any standard-value design that meets the spec is accepted. Some designs run in the simulator, so real effects like op-amp bandwidth or a true diode drop decide whether yours works.

  • Values from the E12 and E24 series
  • Worst-case answers from part tolerances
  • Datasheet limits: absolute maximum and operating ratings
  • Designs checked in the simulator
  • The Bench: wire a circuit, predict a reading, then probe it with a multimeter
  • Netlists you can copy into LTspice

Nothing explodes. A design that only works on paper gets feedback naming the effect it missed.

DESIGN PROBLEMDIVIDERS
Divider from a fixed supply
Source12 V Output3.0 V, within 5% PartsR1, R2 from E24, 1 kΩ to 100 kΩ AnswerR1 30 kΩ · R2 10 kΩ Result3.00 V · accepted
WORST CASEREAL COMPONENTS
Circuit12 V · R1 3.9 kΩ · R2 1.2 kΩ, ±5% Nominal2.82 V Highest3.05 V (R2 +5%, R1 −5%) Lowest2.61 V (R2 −5%, R1 +5%)
+7.9% Both errors push the ratio the same way, so the output moves by more than 5%.

03 · CORRECTNESS

Correct, or it doesn't ship.

A wrong answer costs more trust than a missing topic. Problems go through these checks before they reach you.

ComputedAnswers come from formulas, never typed in by hand.
TestedEach problem type is checked against a hand-worked value.
Cross-checkedSelected circuit problems are re-derived independently by the built-in simulator.
ReviewedContent is verified and reviewed against cited sources.

Found a mistake anyway? Every problem has a Report a problem button. Reports are read and fixed.

04 · WHAT'S IN IT

From charge to particle physics.

Circuits Electronics Digital logic Signal processing Math Physics Particle physics

In Early Access now: circuits and electronics, 50 topics from charge and current through op amps, diodes, transistors and MOSFETs, plus reading schematics and SPICE. The other subjects are planned, and each will be written, checked and reviewed before it ships.

05 · FREE

Learning is free. Forever.

Every topic, problem and tool is free. No ads, no paid learning, no selling your data. Spark Chamber is supported by people who find it useful.

Support Spark Chamber Optional, on Ko-fi: [KO-FI LINK]. Support is not tax-deductible.