Found in an American publication from 1968, this circuit can be made based on a TIP42 that must be mounted on a heat sink. The transformer is 25 V with a current of 3 to 4 A.
This traditional configuration that any Series 139 comparator can use is found in the 1990...
The circuit shown in the figure can be used to detect vibrations or to provide amplified acoustic...
This toy organ was found in Popular Electronics from January 1967. It can be constructed from...