This circuit is from an old Signetics documentation. It can be implemented with modern operational amplifiers. The power supply must be symmetrical.
This circuit monitors the humidity of a pot or plant bed, providing indication on two LEDs. The...
This “zero crossing detector” was found in a manual of operational amplifiers from the 1980s....
This narrowband data receiver is from the Philips Databook of 1990. The circuit is powered by 5 V...