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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
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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
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
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 Tube Diode
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)
Ge doped with Arsenic (As) Note the extra electron
Ge doped with Indium Note missing electron
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
Op-Amps– Equivalent Circuit Transistor Symbol
Output voltage is negative of input voltage Gain (G) is equal to G=-R2/R1 Inverting, unity amplifier when R2=R1 If we replace R2 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 R1 with a capacitor-then lower frequencies are attenuated Called a “high pass filter” Sometimes called a “differentiator” Inverting Amplifiers
G= 1+ (R2/R1) Non-inverting Amplifiers