1/4" (Garber)
3/8"
October 24, 2011
October 23, 2011
Timing Belt & Pulley
October 17, 2011
October 16, 2011
October 14, 2011
Dual H-Bridge: L293DNE
An H-Bridge is an integrated circuit chip that allows electricity to pass across an element in either direction (+V ↔ Ground). It is made of four switches, either solid state or mechanical.
L293DNE: 4-Channel Motor Driver 16-Pin Plastic Dip Tube (Jameco)
Bipolar Stepper Motor
12V Bipolar (Sparkfun)
Torque: 2.3 kg*cm
Angle: 1.8°±5% (200 Steps/Revolution)
AC, BD: Red Green, Yellow Blue
October 12, 2011
Unipolar Stepper Motor
A stepper motor has four terminals connected to two electromagnets. Unipolar steppers have two additional power terminals. The shaft is attached to a gear; the electromagnets have matching teeth that attract the gear as they activate in rotational sequence.
October 11, 2011
Servo Motor (Continuous)
A continuous rotation servo has no potentiometer. The pulse width signal instructs speed and direction instead of position.
Futaba Continuous Rotation (Parallax)
Power: 4-6V
Torque: 2.4 - 3.0kg*cm
Servo Motor (Standard)
A servo motor is a geared DC motor attached to a potentiometer. It has leads for power, ground and signal. The pulse width of the signal instructs the motor to turn until it reaches the correspondant position on the potentiometer. Thus, they have absolute positioning but less than 360° of rotation (usually around 200°).
Futaba Standard Rotation (Parallax)
Power: 4 - 6V
Torque: 2.4 - 3.0kg*cm
Sub-Micro 3.7g (Pololu)
Power: ~4.8V
Torque: 0.6kg*cm
October 10, 2011
DC Motor Circuit
Control speed in one direction:
Arduino, TIP120, Potentiometer
Control speed in two directions:
Arduino, Dual H-Bridge
DC Motor
A DC motor has two leads and will spin when electricity passes between them. The direction of rotation is determined by the direction of the passing current. It is made of two stationary magnets and a commuter (a conductive element that rotates in a magnetic field when electricity is applied). The demonstrated link between electromagnetism and torque is called the Lorentz Force.
October 9, 2011
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)
Subscribe to:
Posts (Atom)