This is a combined circuit of tone generator and preamplifier. We found it in a 1975 documentation. Operational amplifiers of that time can be replaced by modern equivalents.
This special effect circuit with LEDs using the 4017 was obtained in a 1982 publication. LEDs are...
Found in a 1967 Electronics World, this circuit uses unusual components today. The transformer has a high...
In the figure we have the basic configuration of a rectangular oscillator using an operational amplifier...