With a handful of low-leakage passive components and two high-impedance op amps, you can build a sine/square-wave generator with output period of a minute and more.

There are plenty of ways to generate square waves from a microcontroller. Most projects use waveform generator ICs.

This is a very simple square wave generator circuit built with IC 74LS00 that can generate square signals with frequencies between 20 Hz and 1 MHz. Its stability is good enough for most applications.

When [Miroslav] sent in his ‘guerilla homebrew’ square wave generator, we were really impressed. With a relatively simple schematic that uses parts that could be salvaged from old radios, this ...

In this minimalistic square wave generator circuit, the RC network is composed of a 4.7KΩ resistor and a 100nF capacitor. So, we obtain a frequency of approximately 1.5kHz. Since the output square ...

1. The block diagram shows how three low-power audio amplifiers (LM386) are configured to implement a triple-waveform generator at one of two selectable frequencies.

Are there any square to sine wave filter or other in-line options to 'clean up' the power being generated? Any suitably heavy 1:1 transformer should provide significant filtering of output power.