This circuit was taken from an article in Electronics Now magazine in February 1995. The power supply must be dual and other operational amplifier can be used.
This version of the circuit is from 2000, using a source of negative voltage that allows to obtain...
This somewhat complex circuit was found in the May 1984 issue of Radio Electronics magazine. The...
This basic circuit is from an old documentation. The relay must be 50 mA maximum and must have a...