This simple tone control using two transistors was found in an Electronics Today International of the 90s. Transistors are general purpose NPN types, like the BC549 for greater gain.
This circuit can be used as a control shield for microcontrollers of all types. The supply is made...
The figure below shows an AC transconductance amplifier with the National Semiconductor LM3900. The...
This circuit provides a good audio power from a signal at least 1 V of amplitude. The MOSFET must...