Power the weekend like it matters

Weekend projects earn a surprising amount of permanent duty. The breadboard supply you meant to replace becomes the house plant's forever home. Design the rail as if someone will leave it plugged in.

Budget headroom

If the load peaks at 400 mA, do not pick a 500 mA regulator and call it done. Heat, aging, and cable drop eat the margin. Leave room for the day you add one more LED strip because of course you will.

Decouple where the current changes

Caps near the chip. Bulk near the entry. A single capacitor at the barrel jack is not a power architecture; it is a hope.

Protect the future you

Reverse polarity, a fuse or polyfuse, and a clear ground reference cost less than a smoked MCU. Soft-spoken rule: redesign the PSU once early rather than three times after the magic smoke.