Weekly STEM
Tips for builders
Short, practical notes on materials, sensing, and mechanisms — the kind of first-principles advice we put in every Laue Labs pack. One new tip most weeks.
Servo jitter: separate power vs shared Arduino 5V
SG90s brown out or chatter when they share the Arduino’s 5V rail. Give motors their own supply, keep a common ground, and stop chasing “code” for a power problem.
IR tripwire false triggers: ambient light vs modulation
Sunlight and classroom fluorescents can fool a raw IR phototransistor. Modulation — and matching demodulation — is why real tripwires ignore ambient light.
Why birch plywood beats cardboard for keepable builds
Cardboard is fine for a one-weekend mockup. Birch holds screw threads, laser kerf, and the machine you actually want to keep on the shelf.