TurtleBot

Resistor
The current at a given voltage can be controlled with a resistor
$R = \frac{U}{I}$
$I = \frac{U}{R}$
$U = R \cdot I$

Series

$U_{1} + U_{2} + \dots + U_{n} = U_{q}$
$I_{1} = I_{2} = \dots = I_{n} = I_{q}$

Parallel

$U_{1} = U_{2} = \dots = U_{n} = U_{q}$
$I_{1} + I_{2} + \dots + I_{n} = I_{q}$

Types

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Capacitor

Capacitors store electrical charge in electric field

Farad unit (mostly in the nano or micro range) → $1 F = 1 A s / V$

Coils store energy in a magnetic field

Unit Henry → $1 H = 1 V s / A$

Bypass Capacitors

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Crystal
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Diodes
Diode passes current in one direction • Forward voltage drop ~0.7V

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Transistors
Bipolar Junction Transistor (BJT)

switch when current flows B-E

amplified current through C-E

current controlled amplification

MOS-Field-Effect-Transistor (MOSFET)

switch when voltage between G-S

amplified current through D-S

voltage controlled amplification

Transistors form the basis for digital logic
(1947 invented by John Bardeen & Walter Brattain at AT&T‘s Bell lab.)
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Linear voltage regulator

Based on voltage divider

Operates with BJT or MOSFET

Excess energy is converted into heat

Not efficient when $V_{in} >> V_{o u t}$

Drop-Out Voltage

LDO Regulator ( $V_{in} - V_{o u t} < 1 V$ )

Switched voltage regulator

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