Add Canjectors — Chris's custom CAN bus interconnect system

- 12V power + 3 CAN connections per module
- Modeled after SWYFT CANnect after critical CAN failures
- Middle Canjector schematic (EasyEDA, 2026-04-09)
- 120Ω switchable termination, power LED, WAGO terminals

sources/2890/canjectors.md

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+---
+title: "Canjectors — Chris's Custom CAN Bus Interconnect System"
+tags:
+  - hardware
+  - electrical
+  - can-bus
+  - 2890
+  - custom
+type: hardware-spec
+owner: 2890
+status: active
+sources:
+  - "https://swyftrobotics.com/products/swyft-cannect-wiring-system"
+---
+
+# Canjectors — Custom CAN Bus Interconnect System
+
+## Overview
+
+After experiencing **critical CAN bus failures** during competition, Chris designed the Canjector system as a robust interconnect solution for Team 2890's robot. Modeled after the SWYFT CANnect concept but with custom design work, Canjectors provide reliable CAN + power distribution at all critical connections.
+
+The design philosophy: prevent wiring failures from killing the robot mid-match.
+
+## Design Basis
+
+Chris studied the **SWYFT CANnect** system as inspiration:
+- Run CAN bus + 12V power over standardized cabling
+- Easy connector system (WAGO lever terminals)
+- Built-in CAN termination options
+- Robust form factor
+
+Canjectors go further with custom modifications for Team 2890's specific failure points.
+
+## Current Design: Middle Canjector
+
+The schematic shows the "middle" Canjector variant with:
+- **12V power** passthrough
+- **3 CAN connections** (RJ45 connectors)
+- **WAGO terminal blocks** for clean wiring (2601-1104 series)
+- **120Ω termination resistor** (R4) between CAN signal lines — switchable
+- **Power indicator LED** (green, 0603) with 470Ω current limiting resistor
+- **2-pin header** for additional configuration
+
+## Key Features
+
+- **Dual CAN paths** — each Canjector bridges multiple CAN segments
+- **Integrated termination** — 120Ω resistor switchable per segment
+- **Power LED** — visual confirmation that 12V is present
+- **RJ45 connectors** — industry standard, easy to cable, robust
+- **WAGO 2601 series** — tool-free, reliable terminal connections
+- **Designed in EasyEDA** — schematic dated 2026-04-09
+
+## Files
+
+- Schematic: `sources/2890/canjector-schematic.png`
+- CAD (if available): link to repo TBD
+
+## Connection to Training
+
+**For students:** CAN bus failures are among the most frustrating problems in FRC — a loose wire or failed connector kills the whole bus. The Canjector system teaches:
+- **Redundancy** — when one path fails, traffic routes around it
+- **Termination** — 120Ω at each end of the bus, switchable at intermediate nodes
+- **Visual debugging** — power LEDs let you confirm connectivity at a glance
+- **Modular design** — if one Canjector fails, replace it in minutes
+
+## Why This Matters
+
+Chris experienced critical CAN failures at competition. The Canjector system is a direct response — solving the failure mode with custom hardware instead of hoping the stock connectors hold. This is the kind of real-world engineering that separates good teams from great ones.
+
+## Notes for MrC
+
+This is a **confidence builder** for the training vault — it shows Chris's practical engineering under pressure. Good story for students: identify the problem, study existing solutions, design your own, build it, test it. The full engineering cycle, not just code.