Filtering & DC Power Supply Simulator — Reservoir Capacitor Ripple Interactive

Interactive 3D linear power supply workbench with an isolated transformer, bridge module, reservoir capacitor and load bank — adjust source, capacitance and load, inject faults, and measure real ripple instead of assuming perfect DC.

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About the Filtering & DC Power Supply Simulator

This simulator models a complete linear DC supply chassis: an isolated transformer secondary with source resistance feeds a four-diode bridge module, which recharges a reservoir capacitor that in turn supplies a resistive load bank between charging pulses. Adjust secondary voltage, line frequency, bridge diode drop, source resistance, reservoir capacitance and load resistance, and inject reservoir or bridge faults to see how output ripple, mean voltage and stored energy respond.

What the simulator shows

• A real-time 3D cutaway workbench of the isolated transformer and source impedance, the four-diode bridge package, the reservoir electrolytic capacitor, the source-resistance equivalent, the selectable load bank, and the DC return/leakage path, with home view, focus-selected-part, toggleable full enclosure, exploded view, auto-rotate and expand controls, tappable numbered components with callouts matching the diagram reference, and a labels toggle. • Eight live controls: secondary voltage, line frequency (50/60 Hz select), bridge drop per diode, secondary/source resistance, reservoir capacitance, load resistance, a condition selector (healthy, reservoir capacitor disconnected, or load disconnected with 1 MΩ leakage remaining), and a bridge-fault selector (healthy bridge or D1 open giving half-wave recharge). • Play/pause, single-step (0.1 s) and larger-step (1 s) time controls, plus a playback-speed selector from 100x slow motion to 1 minute per second. • A Reset laboratory action, a live "what is happening" sequence narrative with component status tokens and a readings table. • Ten live metrics: secondary sine wave, available bridge (rectified) voltage, reservoir/load output voltage, charging-source current, load current, net capacitor current, last-completed-cycle ripple (V p-p), last-completed-cycle average, stored capacitor energy, and completed measured cycles. • A Curves & measurements tab with two charts (available rectified source vs. reservoir output; source/load/capacitor currents), the complete model equation set, and snapshot measurements. • An Experiments tab with four guided scenarios (normal reservoir, small capacitor, heavy load, disconnected capacitor), 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 (rectify the source, recharge when voltage is sufficient, discharge into the load, measure completed cycles), a knowledge-check quiz with reset, and a written scope/reference statement.

How the reservoir capacitor charges and discharges between peaks

When the conducting bridge pair's available rectified voltage exceeds the reservoir's present voltage, source current flows and recharges the capacitor through the source resistance: C dV/dt = (Vrect − V)/Rs − V/RL. Once the rectified voltage falls back below the reservoir voltage, the bridge stops conducting and the capacitor instead discharges purely into the load: C dV/dt = −V/RL. This charge/discharge cycle — recharging near each voltage peak, then supplying the load alone between peaks — is exactly what produces ripple rather than smooth DC, and is the basis of the small-capacitor and heavy-load experiments.

Reading ripple, energy and the model boundaries

Ripple is measured directly as max(V) − min(V) over the last completed input cycle, not imposed from the small-ripple approximation ΔV ≈ Iload/(2fC) — that formula is shown as a trend reference alongside the measured value. Capacitor current is the difference between source and load current (Icap = Isource − Iload), and stored energy follows E = ½CV². Disconnecting the reservoir capacitor removes the smoothing entirely, so the output simply follows the pulsating rectified waveform down to zero at every crossing.

This is a linear reservoir/load integration model using a midpoint-held rectified source over steps of at most 20 µs, with constant diode drops and resistive source impedance. It excludes voltage regulation, capacitor ESR, ripple-driven temperature rise, transformer saturation, and mains-side wiring. Component changes are treated as new design experiments at the retained state, not a model of physically swapping energized parts; use Reset laboratory to start a fresh trial.

Frequently asked questions

When does the bridge actually recharge the reservoir capacitor?

Only when the instantaneous rectified source voltage exceeds the capacitor's present voltage. Once the source voltage falls below the capacitor voltage, the bridge stops conducting and the capacitor discharges into the load alone until the next voltage peak restores sufficient rectified voltage.

Does using a much larger reservoir capacitor remove all practical limits?

No. A larger capacitor reduces ripple, but source impedance and the pulsed nature of charging current still matter — recharge current is limited by the source resistance, and stored energy still has to be replenished from the source path every cycle.

Why does disconnecting the reservoir capacitor change the output so drastically?

With the capacitor disconnected, there is no energy storage to bridge the intervals between rectified voltage peaks, so the output voltage simply follows the pulsating rectified waveform and touches zero at every zero-crossing, instead of sagging gradually between peaks.

What does this filtering/supply model not include?

It excludes voltage regulation, capacitor equivalent series resistance (ESR), ripple-related temperature rise, transformer core saturation, and mains-side wiring effects. Diode drops are constant, source impedance is purely resistive, and ripple is measured over the last completed input cycle rather than assumed from a formula.

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