Fairchild Semiconductor announces a web-based Offline Power Supply Toolkit, that enables designers to reduce design cycle times while addressing specific application requirements. The toolkit features tutorials, selection tools, and design aids specifically addressing AC/DC topologies. The magnetic reminder is a tutorial that serves as a primer on the practical application of magnetics in power supply design. Design-oriented tools use customer-defined system criteria to aid in the selection of Fairchild products including PWM (pulse width modulation) controllers, the Fairchild Power Switch (FPS) family of products, optically isolated error amplifiers, power MOSFETs, and other components. Anonline tutorial allows designers to decide between flyback, forward converter, and quasi resonant topologies; evaluate basic operation information and advantages and disadvantages of each topology; and review background information for choosing optimal topology for a particular design.