The cut-off frequency of the circuit shown in the figure is 750 Hz, with the components used. The circuit applies to almost any operational amplifier and the power supply must be symmetrical.
Found in a 90s Radio Electronics, this circuit can be used in high voltage experiments, ionizers,...
This VFO circuit generates signals from 2 Hz to 50 Hz. We found it in Popular Electronics from...
This circuit, published in the 1980s, can be applied to operational amplifiers of almost any type....