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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When Docker Starts Before Your Network Storage: Building a Safe Retry Watchdog
A Docker container can fail before its application process ever runs when an SMB or NFS mount is unavailable. Here is a reusable, app-agnostic way to wait for…
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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.