Photoresistor

Photoresistors are semiconductors made of Cadmium Sulfide (CdS), whose resistance decreases as the light shone upon it brightens.

Resistor

Resistors are semiconductors that resist a proportion of the electricity passed through them. This proportion is defined by Ohm's Law: I = V/R. Thus, Ω is a unit of volt-per-ampere. Resistors in series equal the summation R1 + R2 + ... + Rn and for resistors in parallel, the summation 1/R1 + 1/R2 + ... + 1/Rn. The color bands indicate the strength of the resistor, as per this system.

150Ω

33Ω

Relay

A relay has an electromagnetic coil that, when activated, flips an armature between contact points. They can handle a wide range of voltage and come in four types: Single Pole Single Throw (SPST), Single Pole Double Throw (SPDT), Double Pole Single Throw (DPST), or Double Pole Double Throw (DPDT).

Breadboard

A breadboard is a wired matrix for prototyping circuits. The rows are connected, the columns are not (excepting the red and blue power and ground columns when present). The rows are not connected across the central gutter.

Button & Switch

Buttons and switches allow digital (as in fingers) control over a given point in the circuit. They can be Normally Closed (NC) or Normally Open (NO), and are either Momentary or Toggle types.

Battery

AAA

AA

9V

Power Supply

In an Alternating Current (AC), electrons are constantly switching directions. Wall outlets supply AC.





In a Direct Current (DC), electrons flow from Ground (-) to Supply (+). Batteries supply DC.