Found in a 90's EDN, this circuit controls both the speed and the direction of rotation of a stepper motor. Relays can be replaced by MOSFETs, with circuit adaptations.
This voltage regulator for automotive use was found in a Radio Electronics from the 80s. The Q3...
This circuit was found in a 73 magazine for radio amateurs of the 90s. The circuit uses two types...
This circuit was found in 1967 General Electric documentation. The transistors of the time can be...