This circuit was suggested by Sprague Electric in an 80's documentation. The circuit uses a tachometric sensor for feedback. The current was not indicated in the original documentation.
This circuit was found in an Elektor from the 90s. The integrated circuits are not very common...
This differential amplifier, found in a 1964 Electronic Design, has a gain of 30. The setting can be...
This negative resistance circuit was obtained from a 1969’s American documentation. It can be made...