The circuit shown is from 1994 National Semiconductor documentation but can be implemented with more modern operational amplifiers. The power supply must be symmetrical.
This passive tuned circuit was found in a 90s Popular Electronics. The coils must be according to the...
This circuit is suggested by Motorola and is based on the well-known 723, integrated voltage...
This circuit appears in other versions in this same section of the website and in other sections with...