This circuit was obtained in the 1990 Motorola Linear Databook. The circuit uses a 139 series comparator, but other series can be used. The power source need not be symmetric.
We found this circuit in a 1991 Hobbyst Electronics. The circuit makes use of an unusual...
This circuit, from an old publication, can employ silicon transistors like the BC548 and the...
This circuit was found in a 1980s documentation. Similar configurations appear in the section, but from...