This small control for DC motors up to approximately 1 A uses an operational amplifier that admits equivalent. The transistor can be TIP29 for currents up to 1 A or BD135 for 500 mA.
In this application, from English documentation, we have the way to activate an AC load up to 10 W...
This benchtop AC and DC power source was published in the December 1957 Radio Electronics...
The circuit presented is from the Motorola Linear Databook of 1990. The integrated circuit is a...