This text integrates engineering principles with real applications from a systems perspective, providing a framework for developing electronic instrumentation, from hand-held devices to consoles. It offers practical design solutions, describes the interactions, trade-offs, and priorities encountered and then gives specific examples. Written as a principle text for a senior design class, it also serves as a reference handbook for practising engineers. While the focus is on projects often found in medium sized companies, many of the principles presented apply to larger companies as well.