This circuit is from a Popular Electronics from the 90's. The audio amplifier admits equivalent. The others integrated are not very common today.
This amplifier, common in 1986, uses a hybrid integrated circuit that can offer some difficulty to obtain...
This circuit was found in the May 1982 issue of Radio Electronics magazine. The circuit inverts the...
Found in a radio amateur magazine of the 1980s, this circuit uses components that can still be...