One resistor pack, four ballasts

by ourcircuits

6 parts

A resistor array packs four identical, fully isolated 330 Ω sections into one part — here each section ballasts a different-colour LED from the same 0–5 V triangle rail. The resistors are equal but the currents are not, because each LED's real junction model holds its own forward voltage: measured peaks of 9.6 mA (red), 9.0 mA (yellow), 8.7 mA (green) and 5.8 mA (blue). Four different answers out of one component is the whole point — the sections share a package, not a node.