A simple logic circuit that is used to connect complex logic circuits together. For example, an ASIC chip may contain large functions, such as a microprocessor, memory block or communications ...

Contemporary logic circuits use MOSFETs as the elements to build gates, but there are many ways to implement them. Using relays is one of them, and you can literally see how they work.

The simplest possible step-down circuit is a resistive divider. Drive your 5V output into a chain of resistors, from which you tap your 3.3V logic input. A chain consisting of a 2.2k and a 3.3k ...