Difference between revisions of "Optoelectronics"

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(LEDs)
 
(LCDs and where to get them)
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LEDs are diodes that have a voltage drop designed to produce visible light.  When using a LED in a cicuit it's important to use a current limiter such as a resistor.  A typical LED is designed for aproximately 10mA.  When using resistors measure the foreward voltage drop of the LED with a multimeter, subtract this from the supply voltage, then plug the difference into ohms law to calculate the required resistor value.  Different color LEDs all have different voltage drops.
 
LEDs are diodes that have a voltage drop designed to produce visible light.  When using a LED in a cicuit it's important to use a current limiter such as a resistor.  A typical LED is designed for aproximately 10mA.  When using resistors measure the foreward voltage drop of the LED with a multimeter, subtract this from the supply voltage, then plug the difference into ohms law to calculate the required resistor value.  Different color LEDs all have different voltage drops.
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== LCDs ==
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* Serial - These displays have a microcontroller on the display with a serial or I2C connection.  Several builtin fonts are typically included.  These displays are very easy to use, but the update rate for a display is very slow. Fullblown bitmap support is usually not available.  Typical price for these displays is $50+.
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* Parallel - Parallel displays connect to a microcontroller via a parallel interface( the bitwidth varies from 8bits to 32bits ).  Displays can have a much faster update rate then serial since they allow arbitrary graphs to be display.  The displays are typically much cheaper then serial display starting as low as $20.
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Finding LCD displays is not easy since huge distributors such as Digikey have a limited selection.
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Some places that do have LCDs for hobby use:
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[http://www.sparkfun.com Sparkfun] - Has a good selection of both parallel and serial displays. 
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[http://www.matrixorbitral.com MatrixOrbitral] - Specializes in serial display especially the type for direct connection to a PC.
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[http://www.jameco.com Jameco] - A small selection. Mostly serial.

Revision as of 17:04, 18 December 2007

LEDs

LEDs are diodes that have a voltage drop designed to produce visible light. When using a LED in a cicuit it's important to use a current limiter such as a resistor. A typical LED is designed for aproximately 10mA. When using resistors measure the foreward voltage drop of the LED with a multimeter, subtract this from the supply voltage, then plug the difference into ohms law to calculate the required resistor value. Different color LEDs all have different voltage drops.

LCDs

  • Serial - These displays have a microcontroller on the display with a serial or I2C connection. Several builtin fonts are typically included. These displays are very easy to use, but the update rate for a display is very slow. Fullblown bitmap support is usually not available. Typical price for these displays is $50+.
  • Parallel - Parallel displays connect to a microcontroller via a parallel interface( the bitwidth varies from 8bits to 32bits ). Displays can have a much faster update rate then serial since they allow arbitrary graphs to be display. The displays are typically much cheaper then serial display starting as low as $20.

Finding LCD displays is not easy since huge distributors such as Digikey have a limited selection.

Some places that do have LCDs for hobby use:

Sparkfun - Has a good selection of both parallel and serial displays. MatrixOrbitral - Specializes in serial display especially the type for direct connection to a PC. Jameco - A small selection. Mostly serial.