TABLE OF CONTENTS This appendix gives a hobbyist level introduction to basic circuits, and covers the passive components used in this book's schematics.
Current is the flow of electrons through a conductor. A conductor is anything that allows current flow. A good conductor offers little resistance to current flow; in other words, it does not take much work for current to flow within a good conductor. In rough terms, the amount of work it takes to move electrons between two points on a conductor is voltage. The voltage difference between one end of a conductor and the other end of a conductor indicates the resistance of the conductor. If the voltage drop is high, the resistance is high; conversely, if the voltage drop is low, the resistance is low. A voltage supply provides a source of current at a fixed voltage level. Current is measured in Amperes (A), with a few milliamperes (mA, 1 mA = 0.001 A) being the typical current requirements of the integrated circuits used in this book. Voltage is measured in volts (V) and resistance is measured in ohms ( ?). The PIC18 and the integrated circuits in this book require a Direct Current (DC) voltage supply, typically with a voltage value of +5 V. A DC voltage supply means that the current flows in one direction only, and that the voltage is a constant value, either positive or negative. By contrast, the power available for...
