Basic Electronic Components

Crystals

Equivalent Circuit to Crystal

Crystal– Schematic Symbol

Piezoelectric Crystals “Squeezing” the crystal produces an EMF Squeeze the x-axis and a voltage difference occurs on the y-axis Place a voltage difference on the y-axis and the x-axis contracts or expands

Switches

Relays Relay Consists of two parts: coil and switch Current flowing through the coil will create magnetic field A strong enough magnetic field will pull the switch When current stops, switch moves back into original position SPST– Single Post, Single Throw SPDT– Single Post, Double Throw– three switch positions

Light Bulb

Tube Diode Tube diodes have three elements Filament—Heats up cathode so it can donate electrons easily Anode (positively charged plate)– emitter of electrons Cathode (negatively charged plate)—collector of electrons Current only flows in one direction from anode to cathode When “reverse biased”, no current flow

Effect of Diode on AC voltage source

Diode plus capacitor

Triode—Addition of another element called the “grid” Grid is a metallic mesh (holes to let electrons flow through). How many electrons flow through grid depends on charge Negatively charged grid repels electrons Positively charged grid attracts electrons The ratio of the voltage into a triode to the voltage supplied by the triode is called the “gain” (gain=voltage out/ voltage in)

Old School– Cathode Ray Tube (CRT)

Structure of germanium (similar to silicon)

Ge doped with Arsenic (As) Note the extra electron

Voltage applied to Ge(As)

Ge doped with Indium Note missing electron

Voltage applied to Ge(In)

A PN junction Ge(In) + Ge(As) Note more positive charge carriers on left than right

Applying a positive voltage to the N side (called reverse biased)

A forward biased PN junction Note that the behavior of a PN junction is exactly like that of a diode Current can only flow one way

Schematic Diagram of Diode Other diodes: Light Emitting Diodes (LED) Give off light as current passes through them Dark when forward biased

How Transistors Work

Op-Amps– Equivalent Circuit Transistor Symbol

Chip Layouts for Op Amps

Schematic and Necessary Inputs to Op Amps

Inverting Amplifiers Output voltage is negative of input voltage Gain (G) is equal to G=-R 2 /R 1 Inverting, unity amplifier when R 2 =R 1 If we replace R 2 with a capacitor– circuit becomes an integrator Since G is now a function of w, then lower frequencies are amplified with a greater than 1 gain Called a “low pass filter” If we replace R 1 with a capacitor- then lower frequencies are attenuated Called a “high pass filter” Sometimes called a “differentiator”

Non-inverting Amplifiers G= 1+ (R 2 /R 1 )