Basic Electronics and Theory

Introduction

Basic Electronics — unit conversions, Ohm's Law, power, reactance, resonance, and measurement

Metric Prefixes — pico, nano, micro, milli, kilo, Mega, and Giga from trillionths to billions
Conversion Examples — megahertz to kilohertz, milliamperes to amperes, picofarads to microfarads

Conductors and Insulators — silver is best conductor, copper most common, gold resists corrosion; glass, rubber, plastic, mica, ceramic are insulators
Electric Current — flow of electric charge; resistance measured in ohms; conductance is reciprocal of resistance in siemens

Power — voltage times current equals power in watts; a 60 watt bulb at 120 volts draws 0.5 ampere

Transformer — two windings coupled magnetically; turns ratio determines voltage; secondary voltage over primary equals turns ratio
Resistor Power Ratings — larger resistors handle higher power dissipation; power rating is heat a resistor can safely dissipate

Ohm's Law — voltage equals current times resistance; a 12 volt supply across 100 ohms draws 0.12 ampere

Series Circuits — total resistance is sum of individual resistances; same current flows through all resistors; voltage drops add up
Parallel Circuits — reciprocal total resistance equals sum of reciprocals; voltage same across all branches; two equal resistors give half

Frequency — cycles per second measured in hertz; audio range is 20 hertz to 20 kilohertz; radio frequencies above 20 kilohertz
Harmonics — integer multiples of fundamental frequency; second harmonic is twice the fundamental; pure sine wave has no harmonics

Decibels — logarithmic power ratio; doubling power adds 3 decibels; quadrupling adds 6 decibels; halving subtracts 3 decibels

Inductors and Capacitors — inductors add in series but use reciprocal formula in parallel; capacitors behave opposite to inductors

Reactance — inductive reactance increases with frequency; capacitive reactance decreases with frequency

Resonance — inductive and capacitive reactance equal; parallel gives maximum impedance; series gives minimum

Impedance — total opposition to alternating current; the combined effect of resistance and reactance

Voltmeter — connected in parallel across the component under test; very high internal resistance
Ammeter — connected in series; very low internal resistance; never connect in parallel across a voltage source

Unit Conversions — megahertz to kilohertz multiply or divide by 1000; milliamps to amps divide by 1000; picofarads to microfarads divide by 1 million
Conductors and Insulators — silver best conductor, copper most common, gold resists corrosion; glass, rubber, plastic, mica, ceramic are insulators
Ohm's Law and Power — E = I × R; P = E × I; use the triangle to find any unknown value
Series and Parallel Circuits — series total equals sum; parallel total uses reciprocal formula; same current in series, same voltage in parallel
Transformers and Power Ratings — secondary voltage over primary equals turns ratio; larger resistors have higher power rating
Decibel Power Ratios — doubling power adds 3 decibels; quadrupling adds 6 decibels; ten times adds 10 decibels; halving subtracts 3 decibels
Inductor and Capacitor Combinations — inductors add in series, reciprocal in parallel; capacitors behave opposite
Reactance — inductive reactance increases with frequency; capacitive reactance decreases with frequency
Resonance — inductive and capacitive reactance equal; parallel circuit gives maximum impedance; series gives minimum impedance
Measuring Instruments — voltmeter in parallel with high resistance; ammeter in series with low resistance; never connect ammeter in parallel