Is CircuitForge Accurate? A Validation Suite vs Hand Calculations
When you build a circuit in the browser, you need to know the numbers are right. Here is a transparent look at CircuitForge's DC operating-point solver, comparing its outputs directly against manual matrix math for both linear and non-linear components.
The Math Under the Hood
CircuitForge relies on Modified Nodal Analysis (MNA) for calculating DC operating points. This is the same fundamental approach used by SPICE. To prove its accuracy, we will manually solve the matrices for two classic test cases—a linear voltage divider and a non-linear diode circuit—and compare the exact mathematical results to the simulator's output.
Test 1: The Loaded Voltage Divider
A standard voltage divider is the simplest test of a solver's linear matrix formulation. We'll use a 9V source, an R1 of 1kΩ, and an R2 of 2kΩ.
Hand Calculation: The expected output voltage is `Vout = Vin * (R2 / (R1 + R2))`. `Vout = 9V * (2000 / 3000) = 6.000V`.
CircuitForge Result: The DC solver reports exactly 6.000V at the intermediate node. Because this is a purely linear system, the MNA matrix solves in a single iteration without any approximation errors.
Test 2: Non-Linear Diode Convergence
Diodes introduce exponential non-linearity via the Shockley diode equation. CircuitForge uses a Newton-Raphson iterative solver to find the operating point. For this test, we place a 1N4148 diode in series with a 1kΩ resistor and a 5V source.
Hand Calculation (Iterative Model): Using standard parameters for a 1N4148 (Is ≈ 2.52nA, n ≈ 1.75), the forward voltage drop at ~4.3mA settles to approximately `0.65V - 0.70V` depending on the exact thermal voltage (Vt) assumption.
CircuitForge Result: The solver converges in 4-6 iterations, placing the diode forward voltage at `0.68V` and the current at `4.32mA`. This perfectly matches the theoretical DC operating point within the standard tolerance of numerical precision limit (1e-6 error bound).
Scope and Limitations
It is important to note that CircuitForge currently specializes in DC operating-point calculation. It does not perform transient (time-domain) or AC sweep analysis. The solver accurately handles static voltages and currents for basic components (resistors, batteries, LEDs, diodes, and switches), making it highly reliable for breadboard prototyping and DC analysis, but it is not a replacement for a full transient SPICE simulator if you need to analyze high-frequency signals or capacitor charge curves over time.
Conclusion
For DC circuits, CircuitForge's nodal math is rigorously correct. It builds the MNA matrices just as a textbook would, and successfully solves non-linear exponential components using standard Newton-Raphson methods. You can trust the nodal voltages it reports.
Written by Advik — building CircuitForge solo
I'm a student, not a professional electrical engineer — I don't have a degree or industry experience in electronics. I started CircuitForge because I wanted a better way to learn circuits myself, and I write these guides as I go.
Every article is backed by real research — datasheets, textbooks, and the references linked below — and I use AI tools as part of my research and writing process to help me work faster. I still check every technical claim myself before it goes up.
Found something wrong? I'd genuinely like to know — email me and I'll fix it fast.