This circuit is from 1975 documentation. Transistors such as 2N3055 can be used and the transformer is of a special type. R1 is 200 ohms and R2 is 10 ohms.
This circuit is from Popular Electronics from the 90s. The integrated circuit is not very common...
This direct-coupled amplifier was found in Mullard's 1960s transistor manual. The transistors are...
The LM148 and its counterparts are part of a family of low consumption quadruple operators...