Software meets hardware.
Code, circuits, hydraulics, and the things that connect them.
Projects and practical notes by Jon.
From the workbench
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TEKONLINE 8-Zone HVAC Controller V3: ESPHome Firmware with 0–100% Damper Control
Learn how the TekOnline 8-zone ESPHome/Home Assistant V3 uses timed 24VAC damper control, 60-second calibration, direction inversion and safe alpha testing.
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When a Cast Error Is Really a Schema Mismatch
How an apparently unrelated InvalidCastException led to a database and Entity Framework type mismatch—and a practical method for reading stack traces.
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24VAC Three-Wire Damper Wiring: Open, Common & Close
A quick wiring reference for standard 24VAC three-wire HVAC dampers: terminals 1–2 drive open, 3–4 common, and 5–6 drive closed.
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How I Wasted 30 Minutes Trying to Find Paper Towel in Coles
I had a simple mission: paper towel. Not truffle oil. Not an obscure electrical fitting. Paper towel. I checked the toilet-paper aisle. Nothing. I checked cleaning. Nothing obvious.…
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When a Downlight Will Not Fit: Designing a 30mm Cavity Spacer
A practical 3D-printing project for an 85mm downlight opening in a shallow concrete-slab ceiling: a parametric 30mm cavity spacer, with essential electrical and fire-safety limitations.
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Codex CLI Auto-Allow Permissions: Run Commands Without Approval Prompts
Codex CLI asks for approval before it writes files or runs commands. Automation tasks stall while you answer prompts. This guide shows the flags and settings that let…