This amplifier circuit with two transistors was found in a Mullard transistor manual from 1960. The circuit has a maximum output current of 1.3 A.
This small experimental transmitter with the CK722 transistors was found in Radio Electronics...
The supply can be between 4 and 10 V in this circuit and R4 is necessary when the supply is less...
Other operational amplifiers can be used in this conventional filter that rejects only one...