Falstad Electronic Circuit Simulator

Simulation

Free
No Download/Install required
No registration

https://www.falstad.com/circuit/

Falstad electronic circuit simulator solves analog and digital circuits in real time and animates the result on the schematic. Green marks positive voltage, red marks negative voltage, and moving yellow dots show current.

Any component can be edited with a right click, and a large menu of example circuits covers filters, oscillators, op-amp stages and logic.

The originality is the live visual feedback. Switches respond to a click, values change while the simulation runs, and the effect appears immediately instead of after a separate run. A standalone offline version and an AVR8js variant for microcontroller code are also published by the author.

Electronic engineers can use it to sanity check a topology before opening a full SPICE package. Scientists and product developers get a fast way to test an RC time constant, a resonant LRC circuit or a sensor front end, and to explain the behavior to colleagues without installing anything.

Disciplines: Electronics, Electrical engineering, Education, Physics, Audio engineering.

Free alternative to LTspice, Multisim, PSpice, Proteus.

Falstad Electronic Circuit Simulator compared with LTspice, Multisim, PSpice and Proteus
Falstad Electronic Circuit Simulator	LTspice	Multisim	PSpice	Proteus
Simulation scope: Circuits are animated while they run: green marks positive voltage, red negative voltage, and moving yellow dots show current. Switches respond to a click and values can be edited during the run. The page does not list analysis types.	Simulation scope: A SPICE simulator with schematic capture and a waveform viewer. Tutorials show transient, AC and noise analysis, and support for transformers and behavioral sources.	Simulation scope: SPICE simulation and circuit design for analog, digital and power electronics, aimed at education and research. The Designers edition adds PCB design tools.	Simulation scope: Core DC, AC and transient analysis, plus Monte Carlo, worst-case, sensitivity, smoke and noise analyses and parametric sweeps. Co-simulation with MATLAB and Simulink is listed.	Simulation scope: Mixed-mode SPICE run together with microcontroller firmware that executes on a chip model. The optional Advanced Simulation module adds frequency, distortion, noise and sweep analyses.
Platform and installation: Runs in the browser. Standalone offline versions and an AVR8js variant for microcontroller code exist. The source repository also describes an Electron desktop build.	Platform and installation: Windows 10 and 11 (x64), Windows 11 ARM64 and macOS are offered. Windows XP and some older macOS builds are listed as end of support.	Platform and installation: Desktop software plus Multisim Live, a browser-based version for any device. NI is now part of Emerson.	Platform and installation: Part of the OrCAD X platform, run from OrCAD X Capture. The platform works across desktop and cloud environments.	Platform and installation: Proteus 9 has a 64-bit architecture. Supported operating systems are not named on the simulation page.
Licence and cost model: Free software released under GPL version 2 or later in the circuitjs1 repository.	Licence and cost model: Free, with downloads at no charge from Analog Devices.	Licence and cost model: Subscription or perpetual licence, bought online by part number or by quote. A free trial and a student download are offered.	Licence and cost model: Commercial, with a free trial and an Academic Free License.	Licence and cost model: Sold as packages and bundles, with a quotation configurator. Advanced Simulation is a separate option. A free demo and education discounts are offered.
Models and component libraries: A menu of example circuits covers filters, oscillators, op-amp stages and logic. The repository mentions added components such as a Zener diode, spark gap and T flip-flop.	Models and component libraries: Analog Devices macromodels and demo circuits for selected parts, with third-party model support.	Models and component libraries: Multisim Live holds a database of over 30,000 community circuits.	Models and component libraries: Hundreds of behavioral models and vendor-specific components.	Models and component libraries: Many thousands of embedded SPICE models, and over 750 supported microprocessor variants.
Exchange and design flow: Circuits load from URLs or files, can be shared by link and can be embedded in an iframe.	Exchange and design flow: Several Analog Devices tools can export circuits as LTspice schematics, among them Analog Filter Wizard and LTpowerCAD.	Exchange and design flow: The Designers edition combines SPICE simulation with PCB design.	Exchange and design flow: Simulation runs from the schematic inside OrCAD X Capture.	Exchange and design flow: Designs can be netlisted for layout in Labcenter PCB products or in third-party PCB tools.

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