This simulator models a DC supply and series resistor driving a wound, gapped magnetic-core inductor, with a source switch that can open to force stored magnetic energy through a selectable flyback suppression path. Sweep supply voltage, coil turns, core air gap, relative permeability, series and winding resistance, and compare how different flyback clamp voltages trade off decay speed against switch voltage stress.
• A real-time 3D cutaway workbench with a source and series resistor, a source-switching device, an enamelled copper winding on a bobbin, a gapped two-half magnetic core, animated flux reference loops, a diode-like flyback suppression path, and a current shunt/field probe — with home view, focus-selected-part, toggleable full enclosure, exploded view, auto-rotate, expand and show/hide-labels controls, tappable numbered components with callouts matching the companion diagram. • Eight live controls: DC supply (1–24 V), coil turns (100–600), core air gap (0.1–3 mm), relative core permeability (100–1000), external series resistor (5–50 Ω), winding resistance (1–10 Ω), a source-switch-closed checkbox, and a suppression-path clamp selector (0.7 V diode approximation / 12 V clamp approximation / 24 V clamp approximation). • Play/pause, single-step (0.1 s) and larger-step (1 s) time controls, plus a playback-speed selector defaulting to 100x slow motion (100x slow, 10x slow, real time, 10x faster, 1 minute per second). • Reset laboratory plus dedicated Close source (energize) and Open source / release field actions, with a live sequence narrative, operating-point summary and switch-state tokens. • Eight live metrics: winding current, calculated linear inductance, ideal inductive-element voltage, core flux density estimate, stored magnetic energy, winding copper loss, the energized L/R time constant, and the open-switch voltage estimate. • A Curves & measurements tab with winding-current and inductive/switch-voltage charts, the full reluctance/inductance/RL integration equation model, and snapshot measurements. • An Experiments tab with four guided scenarios (current rise, diode flyback, higher clamp, larger air gap), a model-verification bench of independent automated checks, and a timestamped event log with a copyable trial report. • A Learn & assess tab with guided lessons (calculate reluctance, apply a voltage step, release stored energy, compare clamp choices), a knowledge-check quiz and a written scope/reference statement.
Inductance follows a magnetic-circuit reluctance model, ℜ = lcore/(µ0µrA) + gap/(µ0A) and L = N²/ℜ, so even a large relative core permeability is limited by how much reluctance the air gap alone contributes — widening the gap always lowers inductance and, at equal current, lowers stored magnetic energy E = ½LI². While the switch stays closed, current rises exponentially toward i∞ = Vs/(Rseries + Rcoil) with time constant τ = L/(Rseries + Rcoil), exactly the behavior the Current Rise experiment checks against a documented default-fixture value (about 16.16 mH and 1.346 ms at 300 turns and a 0.5 mm gap).
Opening the source switch does not stop current instantly: the inductor reverses its voltage as needed to keep current flowing into whichever suppression path is selected, decaying as i(t+Δt) = max[0, (i + Vclamp/Rcoil)·exp(−RcoilΔt/L) − Vclamp/Rcoil]. A higher clamp voltage (12 V or 24 V) dissipates the stored energy faster than the 0.7 V diode approximation, but it also raises the estimated open-switch voltage stress to roughly supply-plus-clamp — the Higher Clamp experiment is built to make that tradeoff visible directly against the Diode Flyback baseline.
Core flux density is estimated as B = NI/(ℜA), and the simulator flags results above a 0.3 T teaching threshold as a boundary marker rather than switching to a nonlinear saturation model — the underlying inductance calculation stays linear throughout the sweep range. The default playback speed is 100x slow motion specifically because the modeled time constants can be short relative to a comfortable observation window; the animated flux loops are schematic direction/strength indicators, not a finite-element field solution or literal wires.
The model is scoped to a linear magnetic circuit with exact piecewise RL integration and a constant clamp approximation: it excludes core saturation, hysteresis, eddy-current loss, winding fringing effects, diode reverse-recovery time and switch avalanche or arcing behavior, and parasitic winding capacitance is not modeled. Component changes are treated as fresh design experiments at the retained state, not live component swaps on an energized circuit.
An inductor opposes any instantaneous change in its current by reversing the polarity of its own voltage as needed. When the source switch opens, the winding current has nowhere to go except through the selected flyback suppression path, so it decays according to i(t+Δt) = max[0, (i + Vclamp/Rcoil)·exp(−RcoilΔt/L) − Vclamp/Rcoil] rather than stopping the instant the switch opens — this is exactly what the Diode Flyback experiment demonstrates.
A higher clamp voltage (12 V or 24 V, versus the 0.7 V diode approximation) forces stored magnetic energy to dissipate faster because it opposes the decaying current more strongly, but it also raises the estimated open-switch voltage stress to roughly the supply voltage plus the clamp voltage. The Higher Clamp experiment is set up specifically to compare this against the diode-flyback baseline.
Inductance depends on total magnetic reluctance, ℜ = lcore/(µ0µrA) + gap/(µ0A), and the air gap term uses vacuum permeability rather than the core's relative permeability, so even a small physical air gap can dominate the total reluctance. A larger gap therefore lowers inductance (L = N²/ℜ) and, at the same current, lowers stored magnetic energy — the Larger Air Gap experiment demonstrates this and shows current reaching its steady state sooner as a result.
This is a linear magnetic circuit with exact piecewise RL integration and a constant clamp voltage approximation. It excludes core saturation, hysteresis losses, eddy-current losses, winding fringing effects, diode reverse-recovery time, switch avalanche or arcing, and parasitic winding capacitance — flux density above 0.3 T is flagged as a teaching boundary rather than triggering a nonlinear saturation calculation.