Found in Precision Monolithics documentation from the 90's, this circuit equalizes octave signals determined by the capacitor values according to the table next to the diagram.
This circuit was obtained from a 1977 magazine, but can still be mounted using BC548 for TR1 and...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
The figure shows how to add a Darlington stage to an operational amplifier in order to obtain a...