The circuit shown is from a 1994 National Semiconductor documentation and can be implemented with more modern operational amplifiers. The power supply must be symmetrical.
This circuit was suggested by Texas Instruments in a manual of operational amplifiers. Other...
Found in American documentation from the 1980s, this circuit shows how to use an LM3909 pulsator in a...
This circuit was found in an Elektor from the 90s. The integrated circuits are not very common...