Introduction Molecules: made up of atoms of individual elements. Atoms: made up of a nucleus surrounded by orbiting electrons. Nucleus: made up of protons and neutrons. Protons: have a positive charge which attract orbiting electrons, which have a negative charge.

Introduction Electric current is when electrons flow from one atom to the next. Voltage is electrical potential energy. Ohm’s Law is a fundamental equation in electronics: V = R  I; voltage across a component is equal to the current through it multiplied by its resistance.

Atomic Structure Neutron: particle in nucleus of atom having no charge (neutral). Electron: negatively charged particle orbiting nucleus of atom. Orbital path: paths of electrons orbiting atom’s nucleus. Atomic number: number of protons in nucleus of atom.

Introduction Kirchhoff’s Current Law (KCL): explains why current entering a node must equal current leaving node; current cannot be created or destroyed. Kirchhoff’s Voltage Law (KVL): voltage supplied from one or more sources must be the same amount as voltage dropped across one or more circuit elements.

Kirchhoff’s Voltage and Current Laws Figure 2.4: Two resistors in series. Figure 2.9: Two resistors in parallel.

Breadboarding Breadboard: device with hidden interconnections on which to build prototype circuit. Trace: copper line on circuit board connecting one component to another; path for current to flow on circuit board.

Breadboarding Simulation: entering a schematic (drawing) of a circuit to test into a computer program which calculates voltages and currents throughout the circuit without physically building the circuit. Prototype: circuit built functionally the same as a circuit to test.

Introduction Digital electronics is based on the combination and switching of logic levels. Physically, logic levels are represented by voltages. Logic levels are usually specified as 0 or 1 (bits). Each logic level corresponds to a digit in the binary (base 2) number system.

Introduction Time-varying digital waveforms: Periodic waveforms: repeat a pattern of logic 1s and 0s. Aperiodic waveforms: do not repeat. Pulse waveforms: produce a momentary variation from a constant logic level.

Digital Versus Analog Electronics Analog: physical, continuous quantity; analog voltage or current can have any value within a defined range. Digital: physical quantity by a series of binary numbers; can have only specific discrete values.

Digital Logic Levels Logic level: voltage level that represents a defined digital state in an electronic circuit. Logic LOW (logic 0): lower of two voltages in a digital system with two logic levels. Logic HIGH (logic 1): higher of two voltages in digital system with two logic levels.

Binary Inputs Most significant bit (MSB): leftmost bit in binary number; largest positional multiplier. Least significant bit (LSB): rightmost bit of binary number; smallest positional multiplier. Truth table: list of output levels of a circuit corresponding to all different input combinations.

Decimal-to-Binary Conversion Sum of Powers of 2: convert decimal number to binary by adding up powers of 2 by inspection, adding bits to fill up total value of number. Repeated Division by 2: any decimal number divided by 2 will leave a remainder of 0 or 1.

Hexadecimal Numbers Hexadecimal number system: base-16 number system written with sixteen digits, 0–9, and A–F, with power-of-16 positional multipliers. Hexadecimal (hex) numbers: primarily used as shorthand form of binary notation.

Counting in Hexadecimal Table 3.4: Hex Digits and Their Binary and Decimal Equivalents.

Digital Waveforms Digital waveform: series of logic 1s and 0s plotted as a function of time. Timing diagram: digital waveform, typically with multiple signals on one plot.

Periodic Waveforms Periodic waveforms repeat same pattern of HIGHs and LOWs over specified period of time. Clock: special case of a symetrical, periodic waveform with a specified frequency. Time LOW (tl): time during one period that waveform is in LOW state.

Periodic Waveforms Time HIGH (th): time during one period that waveform is in HIGH state. Period (T): time required for periodic waveform to repeat. Frequency (f): number of times per second that periodic waveform repeats. Duty cycle (DC): fraction of total period that digital waveform is in HIGH state.

Pulse Waveforms Pulse: variation of voltage from one logic level to opposite level and back again. Rising edge: part of a pulse where logic level is in transition from LOW to HIGH. Falling edge (trailing): part of pulse where logic level is in transition from HIGH to LOW.

Basic Logic Functions Figure 4.1: Inverter Symbols Figure 4.2: 2-Input AND Gate Symbol

Basic Logic Functions Figure 4.6: 2-Input OR Gate Symbol Figure 4.7: OR Function Represented by Switches in Parallel

Basic Logic Functions Active Level: logic level defined as “ON” state for particular circuit input or output (either HIGH or LOW). Active LOW: active-LOW terminal considered “ON” when in logic LOW state. Active HIGH: active-HIGH terminal considered “ON” when in logic HIGH state.

Derived Logic Functions Figure 4.12: 2-Input NAND Gate Symbol.

Derived Logic Functions Figure 4.13: 2-Input NOR Gate Symbols.

Derived Logic Functions Figure 4.18: Exclusive OR (XOR) Gate Symbols Figure 4.19: Exclusive NOR (XNOR) Gate

DeMorgan’s Theorems and Gate Equivalence Figure 4.21: NAND Gate and DeMorgan Equivalent (positive and negative NAND)

Logic Switches and LED Indicators LED (Light-Emitting Diode): electronic device that conducts current in one direction only and illuminates when it is conducting. Figure 4.31: Light-Emitting Diode (LED)

Enable and Inhibit Properties of Logic Gates Digital Signal (or Pulse Waveform): series of 0s and 1s plotted over time. Enable: logic gate is enabled if it allows a digital signal to pass from an input to the output in either true or complement form. Inhibit (or Disable): logic gate is inhibited if it prevents a digital signal from passing from an input to the output.