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.
In the figure we have a wireless wiretapping circuit for the frequency range determined by L1. For FM...
This voltage follower or amplifier with unit gain uses an unusual operational amplifier nowadays. The...
Found in a 90’s Electronics Now, this circuit has its output connected to an audio amplifier. The...