The circuit of a 1968 publication can be implemented with more modern transistors such as BC548 for NPN and BC558 for PNP.
This circuit for the car was found in the April 1990 Radio Electronics magazine. The speaker is...
We found this circuit in a Texas Instruments documentation from 1973. Other operational amplifiers can...
This circuit was found in a 90's EDN. The circuit has a well-known configuration. The voltage...