Six complete experiment source sets

Read the full article before wiring. These are locally checked designs; no physical test is claimed.

1. ESP32 Terminal Breakout Boards: Map the Connections, Then Test a Button and LED
2. ESP32 + SCD41 CO₂ Monitor: Warm-up, Stale Data and Recovery
3. MCP4726 Voltage Steps: A DAC Code Is Not a Calibrated Power Supply
4. SN74HC165: Freeze Eight Inputs Before Reading Them Slowly
5. DS3231 Time Is Not Automatically Trustworthy: OSF, Calendar and Provenance
6. INA219 Current: Why Zero Can Mean Missing Calibration

Source files retain their original relative diagram, code and worksheet links. Read README.txt for scope and attribution.