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Inverting summing amp (OPA1612 section) mixes STAGE1_OUT (line/instrument) and CLICK_OUT (filtered DAC) at unity into MIX_OUT. Each source enters its own 10k into the op-amp virtual ground, so they sum with no interaction. stage3_sum.cir confirms: each input alone = 0 dB, both together = +6.02 dB, and each input's gain is unchanged by the other (virtual-ground isolation). ERC/netlist 0 errors. Note: inverting summer flips phase -> corrected at the Stage 4 balanced driver via hot/cold assignment. At integration, this summer can use the parked 2nd half of the Stage 2 filter OPA1612 (U4) instead of a separate package. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> |
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| circuits | ||
| sim | ||
| Containerfile | ||
| README.md | ||
| run.sh | ||
PM_K-1 EDA environment
A reproducible container with the tools to design, check, and simulate the core board — so the work doesn't depend on whatever happens to be installed on a given machine, now or in 50 years.
What's inside
- KiCad 9 — schematic capture + PCB layout, and a CLI (
kicad-cli) that can run ERC (Electrical Rules Check) and DRC, and export netlists/PDF/Gerbers. - ngspice — SPICE simulator for validating the analog audio circuits before we commit copper (op-amp stages, filters, input loading, etc.).
- python3 — scripting, BOM munging, optional code-defined-schematic helpers.
Why a container?
The system KiCad here is 7.0, whose CLI can't run ERC (that arrived in KiCad 8). Rather than fight the host, we pin a known toolchain. Anyone — including future-you — rebuilds the exact environment with one command.
Use it
cd hardware/eda
./run.sh # interactive shell, lands in hardware/kicad/
./run.sh kicad-cli version # confirm KiCad 9
./run.sh kicad-cli sch erc pm_k1_core.kicad_sch # run ERC on the schematic
./run.sh ngspice -b ../eda/sim/input_loading.cir # run a simulation (cwd is kicad/)
run.sh builds the image on first use, then mounts the whole repo at /work (so KiCad sees
hardware/). Use RUNTIME=docker ./run.sh … to use Docker instead of Podman.
Layout
eda/
Containerfile # the pinned toolchain (KiCad 9 + ngspice + python)
run.sh # build-if-needed + run with the repo mounted
sim/ # ngspice decks (SPICE simulations of the analog circuits)