This circuit is from 1964 documentation but can be easily implemented based on current components. Input waveforms and detection are shown next to the diagram.
This 1 kHz oscillator uses a Norton LM3900 operating system. The frequency depends on C1 and R1...
This configuration was found in a 1990s documentation. Modern operational amplifiers can be used...
This voltage regulator from STMicroelectronics provides a 1,2 A current in the voltage range from...