PPolySim OS
For Educators · Motor Driver

Motor Driver for a transmission line

Built for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs. Simulate a transmission line live below — adjust the inputs and watch it respond, right in your browser.

DC MotorLive

Controls

Presets

A DC motor speeds up until back-EMF balances the applied voltage, giving a first-order step response. Its steady speed drops linearly with load along the speed-torque line: maximum speed at no load, maximum (stall) torque at zero speed. The green dot is the operating point where motor and load torque match.

▶ Run in Python

Data Inspector

No-load speed240 rad/s
Steady speed224 rad/s
Stall torque0.30 N·m
Current draw0.4 A
Reading this result: Light load: speed stays close to the no-load value, since only a small back-EMF drop is needed to supply the torque.

Governing equation

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

PID ControllerLive

Controls

Presets

A PID controller drives a system to its setpoint using three terms: proportional reacts to the current error, integral eliminates steady-state offset, and derivative damps overshoot. Tuning the three gains trades off speed, overshoot, and stability — the workhorse of industrial control.

▶ Run in Python

Data Inspector

Overshoot0%
Settling time0.00 s
Steady-state error0.000

Governing equation

Reading this result: Balanced gains — proportional for speed, integral to remove offset, derivative to damp overshoot: the textbook well-tuned response.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

3

Transistor Bias

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BJT Transistor BiasLive

Controls

Presets

Voltage-divider bias sets a transistor's operating point (Q-point) stably against variations in β. The base voltage fixes the emitter current, and the collector-emitter voltage falls on the DC load line. For a clean amplifier, the Q-point should sit near the middle of the active region.

▶ Run in Python

Data Inspector

Collector current Ic2.52 mA
Vce8.22 V
Base voltage2.11 V
Regionactive

Governing equation

Reading this result: The Q-point sits near mid-load-line — the sweet spot for a linear amplifier, giving the largest symmetric output swing.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

Bode Plot (2nd-Order System)Live

Controls

Presets

A Bode plot shows how a system responds across frequency: gain in decibels on top, phase shift below. This second-order low-pass passes low frequencies and rolls off at −40 dB/decade above its natural frequency. Low damping produces a resonant peak; high damping smooths it away.

▶ Run in Python

Data Inspector

Natural freq1,000 Hz
Damping ζ0.30
Resonant peak+4.8 dB
Roll-off−40 dB/dec

Governing equation

Reading this result: Low damping ζ=0.30 produces a sharp +4.8 dB resonant peak just below fn — great for selectivity, but it rings in the time domain.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

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Frequently asked questions

Is this good for educators?
Yes — this version of "Motor Driver for a transmission line" is framed for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs.
Do I need to install anything?
No. It runs in any modern browser, free, with no account required.