ICL7660 Charge-Pump Negative-Rail Generator

Turn a single positive supply into a clean +/- pair with one chip and two capacitors — the trick analog circuits use to skip the second power supply.

Difficulty: Breadboard. Estimated build time: about 20 minutes. Estimated parts cost: about US$3.80. 4-part bill of materials with live supplier pricing. A single-chip negative-voltage generator that turns +5 V into -5 V (or +9 V into about -9 V) so you can power an op-amp or rail-to-rail audio circuit from a single positive supply.