The circuit is a triangle waveform generator that uses as few parts as possible. A 555 timer IC, 2 resistors and two capacitors make the triangle wave. The IC is connected in a 50% duty-cycle astable ...

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, ...