Draw: open a component group on the left and click a part (it follows the cursor — click the canvas to drop, repeat), or drag it straight onto the canvas. R/right-click rotates, F flips. Click a pin, then waypoints, then the target pin to wire; Esc cancels. Double-click a part for rotate/flip/delete. Ctrl+Z/Ctrl+Y undo/redo, mouse wheel zooms, drag empty space pans. The Annotations › Text label tool writes titles and notes directly onto the drawing (multi-line, size, colour) — sample circuits get their title stamped automatically.

Adjust anything live: the right-side Inspector edits every value of the selected part in place — sliders for bounded values (wiper position, sizes), selects for modes, unit-parsing text fields for the rest — and applies it immediately, even while the simulation is running. During simulation the Live controls card drives switches, pushbuttons, potentiometers, DC sources and battery cell counts, and relays report their own state (energized / at rest, coil current) — the relay armature and its ENERGIZED flag move on the drawing too.

Simulate: press ▶. Nets are coloured by voltage (blue 0 V → red max), dots show conventional current direction and speed, lamps/LEDs glow by real power, relays clack, fuses and overloaded lamps/LEDs fail visibly. Hover a wire = node voltage; click a part = exact V / I / P.

Samples in three levels: Simple teaches the laws (Ohm, Kirchhoff, dividers, diodes, relays, op-amps), Intermediate applies them (7805/LM317 supplies, shunt sensing, R-2R DAC, LDR/NTC alarms, staircase wiring), and Advanced is real-world class including the new IC designs: LM393 under-voltage alarm, LM358 sensor front-end, ULN2003 relay driver, PC817 opto-isolator and an L293D reversible motor bridge — alongside charger cut-off, instrumentation amplifier, relay H-bridge, constant-current driver, rail splitter and emergency changeover. IC cards marked SIM actually run in simulation; the others are pinout references.

Print / PDF: the toolbar button builds an A4 engineering sheet (title block, watermark, your name) in a new window — print it on paper or choose Save as PDF.

Account: sign in (top right) and ☁ Save keeps the design on this site — reopen it from My designs here or from the deck profile, from any device. Without an account everything stays in this browser (localStorage / JSON export).

Scope (DC, steady state): the solver runs full Kirchhoff + Ohm analysis with Newton–Raphson for diodes/LEDs/zener, behavioural 78xx & LM317 regulators and the sim-flagged IC blocks, fixed-point pass for relays and op-amp output clips. Capacitors are open and inductors short in DC steady state (RC/RL charge curves are a planned update). Parts marked ref (AC source, transformer, speaker…) and non-SIM IC blocks are documentation symbols — drawn to IEC 60617, internals not simulated.

Learning: 30+ electrical lessons from beginner to advanced live in the Learning Hub › Electrical Circuits.