VAR 7-20 of the SR Passives series are a collection of seven passive components, specifically: resistors, capacitors, inductors, diodes, transistors, relays and transformers. These components are designed to provide linear or nonlinear electrical characteristics that improve the performance of electro-mechanical systems. The components can be used in a variety of applications such as audio amplifiers, digital logic designs, motor control circuits, power supplies and switching systems.