This circuit was found in a National Semiconductor manual from the 1980s. The integrated circuits used are equivalent. Note the need for a symmetrical power supply.
This circuit was found in an old American publication. The integrated circuit used is no longer easy...
This circuit is from 1976 documentation. It uses the operational amplifier 709 which is no longer...
This circuit produces the sounds of the two types of siren switched by S3. The circuit is from...