This circuit was found in Texas Instruments documentation from 1968. The transistors are from that time, admitting modern equivalents. The response ranges is from 20 to 20 000 Hz.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...