diodes
diodes are one-way valves for current. they set direction, clamp voltage, and glow (when they’re LEDs).
polarity
fact
current flows from anode → cathode (conventional). the package stripe marks the cathode. flyback (inductive loads)
coils kick when turned off; the diode gives that energy a safe path.
caution
place the diode as close as possible to the coil; orientation: stripe to +. common types
- silicon signal: ~0.7 V drop, general purpose (1N4148).
- schottky: low drop ~0.2–0.4 V (SS14) for efficiency.
- zener: clamps to a set reverse voltage (regulation, protection).
- LED: light + direction; add a series resistor.