CD4049 Hex Inverting Buffer/Converter IC (DIP-16)

Beyond simply inverting a digital signal six times over on one chip, the CD4049 has a specific and useful trick: its inputs can tolerate a higher supply voltage than its output stage runs at, which lets it convert a 5V or higher logic signal down to a lower-voltage logic level a 3.3V device can safely accept. That dual role as both a signal buffer/inverter and a basic level-shifting tool makes it handy for bridging between mismatched logic families, cleaning up a weak signal that needs more drive strength before reaching a downstream chip, or simply inverting several digital signals at once without needing six separate single-gate chips.