October 8, 2011
Transistor (NPN)
A transistor is a semiconductor with three pins such that when one pair are connected, a discrete connection is made between another pair. They are useful as both switches (i.e. logic gates) and amplifiers (a low-voltage signal can control a high-voltage element), and are typically made of Si.
NPN transistors have terminals named Collector, Base and Emitter. A current flowing from Base to Emitter activates a connection between Collector and Emitter, which can be of a much higher voltage.
2N 3904 -K32 (Jameco)
TIP120 NJSTO18 (Jameco)
October 7, 2011
Red Green Blue (RGB) LED
Red, green and blue are the primary colors of light: any color can be defined as proportions of these three. Each pixel of a typical computer screen is a tiny RGB LED. The pins are ordered R - [cathode, longest] - G - B. I often make mistakes here in code because my initials are LBG.
October 6, 2011
Light Emitting Diode (LED)
When electricity passes through an LED, electrons fill electron holes in the semiconductive material, and energy is released in the form of photons. The color the light takes is determined by the band gap of the semiconductor. As with any diode, electricity can only pass in one direction. The cathode is connected to ground, typically has a longer leg, and is topped by an anvil to hold the semiconductor in place.
Diode
A diode is a semiconductor that allows electricity to pass in one direction (cathode to anode) but not the other. The cathode is indicated by a band. It has a crystalline structure, usually Silicon (Si). It is used to protect back-surge from an independently powered element (ex. a reversing motor).
October 5, 2011
Potentiometer
A potentiometer is a variable resistor. It is the electromechanical part of a control knob. It is a means to adjust the amount of voltage being supplied to an element. It is made of a resistive material (ex. Graphite) or a conductive one (ex. Kapton), and the setting of the wiper determines the amount of that material the electricity must pass.
Typical Type (passive)
Trim Type
Slide Type (resistive)
Membrane Type (conductive)
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