====== Electronics ======

prerequisite: [[Electricity]]

===== Electricity vs Electronics =====

electrical circuit - controlled by mechanical switches

electronic circuit - controlled by electronic signals

electronics begins with the vacuum tube and the transistor

==== Resistor ====

Can be used in these ways:
  * current limiting
  * voltage limiting
  * pull-down
  * pull-up

=== Current Limiting Resistor ===

Wire in series with an LED.

A **braking resistor** is a special case of the limiting resistor used in DC motors and 
can be used in three braking circuits: 

  * plugging, or counter-current, braking
  * dynamic, or rheostatic, braking
  * regenerative braking

=== Voltage Limiting Resistor ===

Create a **voltage divider circuit** with two resistors.

Limit voltage to any value.

=== Pull-down Resistor ===

Place between an open switch and ground, to force the switch to appear open.

=== Pull-up Resistor ===

Place resistor between an open switch and the voltage source, to force the switch to appear closed.