Here is a 1Hz pulse/frequency generator using the popular timer IC 555 which is wired as an Astable Multivibrator. The output pulses can be indicated visually by the LED. An Astable Multivibrator, ...

Over on YouTube [Andrew Neal] has a Function Generator Build for Beginners. As beginner videos go this one is fairly comprehensive. [Andrew] shows us how to build a square-wave generator on a ...