This circuit was taken from Maxim documentation from the 1990s. It can be implemented on the basis of modern operational amplifiers. Power supply doesn't have to be symmetrical.
This traditional configuration was obtained in a 1986 publication. The speaker can be replaced by a...
This circuit from an old documentation (1970s) combines the function of cutting or limiting the...
This circuit is from 2002 documentation, requiring a symmetrical source of 6 to 12 V. The signal...