This circuit generates rectangular signals from 2 Hz to 20 kHz using an operational amplifier. The circuit is from 1984 Radio Electronics. The power supply must be symmetrical.
This circuit is from an old American documentation, from 1977, but it can be implemented with more...
This circuit was found in a 1970s American documentation. It can be applied to almost any...
This circuit generates an accurate 1 Hz signal controlled by a crystal. The circuit is from 1995...