Free Advanced Circuit Simulator | Build & Test Online

Design professional-grade electronic schematics and test real-time AC/DC physics directly in your web browser. Our Advanced Circuit Simulator features magnetic wire snapping, infinite 360-degree component rotation, live current flow animations, and precise time-harmonic voltage calculations.

For ECE engineers, hobbyists, and students, visualizing alternating current (AC) and complex diode networks is a major challenge. Our Virtual Physics Engine provides a highly accurate, risk-free environment to prototype your designs. Featuring a dynamic Nodal Analysis solver, the engine maps your topology, applies Kirchhoff's Circuit Laws, and supports time-varying AC sources. Build a full-wave bridge rectifier and watch the current physically alternate directions from the source while maintaining a direct, unidirectional flow through your load resistor. Drop components directly onto wires to auto-splice them, rotate them to any angle, and utilize the smart diagnostics panel to troubleshoot your circuits instantly.

How to Use the Simulator Engine

Our simulator features a powerful Modified Nodal Analysis (MNA) Matrix Solver capable of calculating real-world SPICE parameters flawlessly. Current must flow in a complete, uninterrupted loop.

1. Place a Power Source: Select the DC Battery or AC Source from the toolbar and tap the canvas.
2. Draw & Route ("Sticky Wires"): Draw wires connecting nodes. Unlike basic apps, our schematic features Sticky Routing—if you drag a component afterward, the wires act like rubber bands, securely adapting to the new placement! Our new wire engine also natively understands Parallel T-Junctions, automatically routing currents across parallel component branches.
3. Set Ground Reference [⏚]: Advanced circuits require a 0V anchor point to prevent floating-node paradoxes. Click the Ground icon and attach it to the negative terminal of your circuit.
4. Analyze Live Telemetry: While the circuit is active, click any component. The Inspector displays the precise Current (I) mapped in µA, mA, or A, alongside the exact nodal Voltage drop (ΔV).

Directed Physics: AC Voltage & Diodes

Our MNA engine enforces rigid real-world polarity equations. The flat base of the LED triangle is the Anode (+), and the tip of the triangle is the Cathode (-). Electricity can only flow from Anode to Cathode.

If you use the AC Source, you will literally watch the green directional arrows and electrons dynamically reverse direction. If they hit a backward diode, the matrix solver enforces an instant high-impedance cutoff (Reverse-Bias), natively generating a Half-Wave Rectifier!

Circuit Building Tutorials (Step-by-Step)

Want to test the limits of our online circuit schematic maker? Try building these three standard electrical engineering examples directly in your browser:

1. The Basic LED Flashlight

This is the "Hello World" of electronics. It teaches you how to balance voltage and resistance to prevent burning out a bulb.

• Place a DC Source (Battery) and set its value to 9V using the Inspector tool.
• Place a Resistor and set it to 330Ω.
• Place an LED. Make sure the flat side (Anode) points toward the positive end of the battery.
• Use the Wire tool to connect the Battery (+) to the Resistor, the Resistor to the LED Anode, and the LED Cathode to the Battery (-).
• Result: The LED will light up green, and the telemetry box will show a safe operating current of around 20mA.

2. The Half-Wave Rectifier

Learn how to turn messy Alternating Current (AC) into usable Direct Current (DC).

• Place an AC Source on the left side of the canvas.
• Place a single Diode in series with the top wire.
• Place a Resistor (1kΩ) as your load.
• Connect everything in a simple loop.
• Result: Watch the yellow electron dots. The AC source will push electrons back and forth, but the diode will "chop off" half the wave, only allowing the current to flow forward through the resistor.

3. The NPN Transistor Switch

This circuit demonstrates how a tiny amount of current can control a massive amount of power—the foundational logic behind all modern computers.

• Place a 12V DC Source. Connect a Bulb to the positive terminal.
• Place an NPN BJT. Connect the Bulb to the top pin (Collector). Connect the bottom pin (Emitter) to the negative battery terminal.
• Place a Switch and connect it between the positive battery terminal and the left pin (Base) of the NPN.
• Result: The bulb stays off. Click the switch to close it. A tiny current hits the Base (triggering V_BE > 0.6V), which "opens the gate" and allows heavy current to flow from the Collector to the Emitter, lighting the bulb!

Advanced Logic: BJTs & MOSFETs

Modern microprocessors are built using 3-terminal logic gates. Our simulator handles standard non-linear switching parameters perfectly:

• NPN BJT (Bipolar Junction Transistor): Think of this as an electronic switch. When the Base (V_BE) receives >0.6V relative to the Emitter, the engine forces the Collector-Emitter junction into saturation, permitting heavy external current to flow.
• N-Channel MOSFET: Built for heavy loads. Requires absolutely zero Gate current, relying purely on the static Gate-Source Voltage potential (V_GS > 2.0V) to rapidly open the massive Drain-Source conduit (R_DS(on) = 10mΩ).

How to Fix a Short Circuit

The upgraded engine features Norton-equivalent tracking. If you connect a wire directly from the positive side of the battery to the negative side without an appropriate load, the matrix triggers a CRITICAL SHORT (>50A).

According to Ohm's Law (I = V/R), if Resistance drops to near-zero, Current theoretically approaches infinity. The physics simulator registers the massive amp overload, simulating thermal failure risk, and triggers an orange/red alert to enforce safe EDA practices.

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