CircuitCheck

Photo of a hand-drawn DC circuit in, a solved and checked circuit out.

The problem

Engineering students draw circuits constantly and check their homework by hand. A single wrong resistor formula or sign gives a wrong answer, and there’s no quick way to see where it went wrong.

What it does

1. Upload a photo of a hand-drawn DC circuit (resistors, voltage sources, current sources).
2. Gemma 4 reads the sketch and writes it down as a netlist: components, values, and what connects to what.
3. Deterministic validators check the netlist (ground node, floating nodes, source loops). If a check fails, the specific problem is sent back to Gemma for a repair attempt.
4. A NumPy modified nodal analysis solver computes every node voltage, branch current and power. Gemma never does the math.
5. A student can type their answer. The app compares it with the solved value and shows the true one.

Where Gemma 4 is used

Gemma 4 (via the Gemini API) is the vision model that turns a hand-drawn schematic into a structured netlist. Without it there is no sketch input. All numbers come from the solver, not from the model.

Results

We tested 10 hand-drawn circuits and Gemma read 7 of them correctly. Failures: [one line on what went wrong].

Limitations

• DC circuits with resistors, voltage sources and current sources only. LEDs, diodes, capacitors and transistors are reported as unsupported.
• Drawings need numeric values. A drawing with only symbols returns “values missing” and asks for numbers instead of guessing.
• Messy drawings can be misread. “Solved: checks passed” means the math is consistent, not that the reading is right, so compare the Visual Schematic with your photo.

Built with

Python, FastAPI, NumPy, Pillow, vanilla JavaScript, Gemma 4 via the Google GenAI SDK. Written with Antigravity as the coding assistant during the Hack Day. MIT licensed. Setup and usage are in the README.