How does the Python4Physics Circuit Simulator work?

The circuit simulator employs Modified Nodal Analysis (MNA) with trapezoidal numerical integration to simulate linear and nonlinear analog circuits in real time directly inside your web browser.

Can I connect virtual laboratory instruments like an oscilloscope and multimeter?

Yes. The simulator includes an authentic dual-trace Cathode Ray Oscilloscope (CRO) with dual-channel timebase, Volts/Div, and Trigger controls, as well as a 4.5-digit Digital Multimeter (DMM) for DC/AC voltage, current, and resistance measurement.

What circuit components and semiconductor models are supported?

Supported components include Resistors, Capacitors, Inductors, Potentiometers, DC/AC Voltage Sources, Current Sources, Ground, Silicon/Germanium/Schottky/Zener Diodes, LEDs, NPN/PNP Bipolar Junction Transistors (BJTs), JFETs, MOSFETs, Operational Amplifiers (IC 741), SPST Switches, and Live Voltage/Current Probes.

Is the circuit simulator free for science students and educators?

Yes, Python4Physics is completely free and open for educational use, scientific learning, and coursework worldwide.

Virtual Electronics Laboratory · Interactive Circuit Simulator

Virtual Circuit Simulator & Instruments Suite

A professional browser-based electronics CAD & SPICE simulation environment. Wire active and passive components on the engineering grid, probe nodes with a dual-trace CRO and digital multimeter, and execute real-time SPICE transient simulations across all 9 curriculum modules.

CIRCUIT SIMULATOR

MNA SPICE ENGINE 2.0 · 33 FPS

Sources

Basic / Passive

Diodes

Transistors & FETs

Analog / Op-Amps

In-Circuit Probes

Quick Controls: Click red pins to wire · Drag handles or double-click to bend/tweak wires · Drag components · Press R to rotate · Press Del to remove · Double-click or Enter to edit value

Tektronix · Dual-Trace Cathode Ray Oscilloscope (CRO)

Timebase (Horizontal)

Time / Div:

Channel A (Input)

Volts / Div:

Y-Pos:

+1.0 div

Channel B (Output)

Volts / Div:

Y-Pos:

-1.5 div

Ch A Vp-p: --

Ch A Freq: --

Ch B Vp-p: --

Ch B Freq: --

Agilent 34401A · Precision Digital Multimeter (DMM)

Probe: Auto Probes (RL) 0.000 V

0.000 V DC

Agilent · Function Generator (XFG)

Source: AC Source

Frequency: 1000 Hz

Amplitude (Peak): 5.0 V

AI Circuit Diagram Recognizer & Auto-Simulator

Upload an image or diagram of any circuit (from a textbook, lab manual, exam, or sketch) to generate the component schematic and run the circuit simulation.

Drop schematic image here

PNG, JPG, WEBP or Paste from Clipboard (Ctrl+V)

Or Try Sample Diagram Archetypes:

Bridge Rectifier BJT CE Amplifier Zener Regulator Inverting Op-Amp RC Low-Pass RLC Resonant

Gemini Vision Key (Optional) Built-in AI active

Upload or select a diagram to see recognized netlist and physical simulation components.

Electronics Curriculum & Experimental Physics Modules

Launch pre-built circuits into the circuit simulator with one click to observe and test the theoretical principles.

7 Core Modules · 21 Interactive Circuits

Module 1 · DC Circuits

Circuits and Network (DC) (4)

Discrete active & passive components, ideal constant voltage/current sources, Kirchhoff's laws (KCL, KVL), Thevenin's and Norton's theorem, Superposition theorem, and Maximum power transfer theorem ($R_L = R_{th}$).

V_{th} = V_{oc}, \quad R_{th} = \frac{V_{oc}}{I_{sc}}, \quad P_{max} = \frac{V_{th}^2}{4 R_{th}}

Module 2 · Semiconductor Diodes

Semiconductor Diodes & Applications (9)

PN junction fabrication, barrier potential, static/dynamic resistance, half-wave & full-wave bridge rectifiers, Ripple Factor ($\gamma$), Rectification efficiency ($\eta$), L & C smoothing filters, clipping & clamping circuits, LEDs.

\gamma = \frac{1}{4\sqrt{3} f C R_L}, \quad \eta_{bridge} = 81.2\%, \quad I = I_s\left(e^{\frac{qV}{\eta k_B T}} - 1\right)

Module 3 · BJT Biasing

BJT Transistors & Biasing (10)

NPN & PNP configurations (CB, CE, CC), active, cut-off and saturation regions, DC load line & Q-point, stability factors, fixed bias vs voltage divider bias (self-bias), 2-port hybrid $h$-parameter equivalent circuit.

I_C = \beta I_B + I_{CEO}, \quad V_{CE} = V_{CC} - I_C R_C, \quad S = \frac{1 + \beta}{1 + \beta \frac{R_E}{R_B + R_E}}

Module 4 · FET & MOSFET

Field Effect Transistors (3)

JFET and MOSFET (both depletion and enhancement mode MISFET), pinch-off voltage ($V_p$), drain saturation current ($I_{DSS}$), threshold voltage ($V_{th}$), transconductance $g_m$, and short channel switching characteristics.

I_D = I_{DSS}\left(1 - \frac{V_{GS}}{V_P}\right)^2, \quad g_m = \frac{2 I_{DSS}}{|V_P|}\left(1 - \frac{V_{GS}}{V_P}\right)

Module 5 · Voltage Regulation

Regulated Power Supply (3)

Load regulation and line regulation, Zener diode as shunt regulator, limitations of Zener circuits, error feedback amplifiers, and series regulated power supply using a pass transistor assisted by a Zener voltage reference.

\text{Line Reg} = \frac{\Delta V_{out}}{\Delta V_{in}}, \quad \text{Load Reg} = \frac{V_{NL} - V_{FL}}{V_{FL}} \times 100\%

Module 6 · Amplifiers

Amplifiers & Frequency Response (5)

Common Emitter (CE), Common Base (CB) and Emitter Follower buffer circuits, dynamic load line analysis, Class A, B and C amplifier classification, and midband frequency response with low and high cut-off frequencies ($f_L, f_H$).

A_v = -\frac{h_{fe} R_L'}{h_{ie}}, \quad f_L = \frac{1}{2\pi (R_{in} + R_s) C_1}, \quad BW = f_H - f_L

Module 7 · OP-AMP & Feedback

Feedback Amplifiers & OP-AMP Applications (8)

Open-loop gain, frequency response, CMRR, slew rate, and virtual ground concept. DC & AC OP-AMP applications: inverting & non-inverting amplifiers, inverting summing adder, differentiator as subtractor (difference amplifier), error amplifier, comparator, Schmitt trigger with hysteresis, and operational integrator & differentiator.

V_{out(add)} = -\left(\frac{R_f}{R_1}V_1 + \frac{R_f}{R_2}V_2\right), \quad V_{out(diff)} = -R_f C \frac{dV_{in}}{dt}, \quad V_{UTP, LTP} = \pm \frac{R_1}{R_1 + R_2} V_{sat}

Module 8 · Multivibrators (5)

Multivibrator Circuits & Wave Shaping (5)

Transistor as an electronic switch (CE output characteristics: cut-off & saturation regimes, load line switching). Construction, operating principles, and cross-coupling wave shapes of collector-coupled Bistable (flip-flop), Monostable (one-shot timer), and Astable (free-running square wave) multivibrator circuits with analytical time period expressions.

T_{astable} = 1.38 R_B C \quad (f \approx \frac{0.7}{R_B C}), \quad T_{mono} = 0.69 R_B C, \quad V_{CE(sat)} \approx 0.2\text{V}, \quad I_{C(sat)} = \frac{V_{CC}}{R_C}

Module 9 · Oscillators (3)

Sinusoidal & Relaxation Oscillators (3)

Sinusoidal oscillators & Barkhausen's criterion for sustained self-oscillations ($|A\beta| \ge 1, \angle A\beta = 0^\circ$). RC phase shift oscillator (3-stage RC ladder network $\beta = 1/29$, $180^\circ$ phase shift $+ 180^\circ$ inverting CE stage), Wien bridge oscillator (lead-lag bridge network $\beta = 1/3, A_v \ge 3$), and Op-Amp relaxation square wave oscillator with positive feedback hysteresis.

|A\beta| \ge 1, \angle A\beta = 0^\circ, \quad f_{RC} = \frac{1}{2\pi R C \sqrt{6}}, \quad f_{Wien} = \frac{1}{2\pi R C}, \quad T_{relax} = 2 R C \ln\left(1 + \frac{2R_1}{R_2}\right)