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== Logic Gates ==
 
== Logic Gates ==
  
Logic gates are the building blocks of digital circuits.  Any digital circuit including microprocessors can be built out of the NOT function plus AND or OR.  Different chips are distinguished by speed, voltage level, output drive, and power used.  They are often divided into families which have characteristics in common.  There are hundreds of different types.
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Logic gates are the building blocks of digital circuits.  Any digital circuit including microprocessors can be built out of the NOT function plus AND or OR.   
  
 
Common forms found in discrete gates:
 
Common forms found in discrete gates:
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There are hundreds of other specialized logic gates. Here we only list the ones we actually use in some Open Circuit [[Projects|Project]]:
 
There are hundreds of other specialized logic gates. Here we only list the ones we actually use in some Open Circuit [[Projects|Project]]:
  
* 74HC595 eight bit shift register with output latch (used for [[POV display]]) There are other shift registers, some of quite high power ( generally low side switches ) we should reference some here soon, else google for them.  Some are intended to drive led's.
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* 74HC595 eight bit shift register with output latch (used for [[POV display]])
  
 
* Low pin count( 8 - 12 ) microcontrollers are great for logic gate replacement when high speed is not required.  Athough slower, slightly more expensive, and needing to be programmed they are great for prototyping due to the extra flexibility that comes from not needing to stock lots of gate variations.
 
* Low pin count( 8 - 12 ) microcontrollers are great for logic gate replacement when high speed is not required.  Athough slower, slightly more expensive, and needing to be programmed they are great for prototyping due to the extra flexibility that comes from not needing to stock lots of gate variations.
  
 
* FPGAs are flexible ICs contain a very large number of gates( thousands to millions ) that can be arbitrarily connected together through programming in VHDL.  Only available in surface mount large pin counts.  Many people prototype processor designs with these devices ([http://en.wikipedia.org/wiki/Soft_processor Wikipedia: soft microprocessor]).
 
* FPGAs are flexible ICs contain a very large number of gates( thousands to millions ) that can be arbitrarily connected together through programming in VHDL.  Only available in surface mount large pin counts.  Many people prototype processor designs with these devices ([http://en.wikipedia.org/wiki/Soft_processor Wikipedia: soft microprocessor]).
 
 
Links:
 
 
*[http://focus.ti.com/lit/sg/sdyu001z/sdyu001z.pdf Logic Guide] A useful guide from TI.
 
*[http://www.allaboutcircuits.com/vol_4/index.html All About Circuits - Volume IV - Digital] Part of a useful, free, online text.
 
 
 
== Microcontrollers ==
 
== Microcontrollers ==
  
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== RF ICs/Modules ==
 
== RF ICs/Modules ==
 
Many open-source [[radio communication]] systems use an RF IC.
 
  
 
RF modules allow transmission and reception of digital signals over radio.  The two most common types are AM and FM( FSK ).  The three major frequency bands used by unlicensed devices are 433MHz, 900MHz, and 2.4GHz.  433MHz has very limited uses by the FCC and is mostly used by garage door openers and wireless key entry systems.  Many newer devices are moving to 2.4GHz due to the greater amount of room, althrough 2.4GHz is harder to use and has less range then the same power 900MHz system.
 
RF modules allow transmission and reception of digital signals over radio.  The two most common types are AM and FM( FSK ).  The three major frequency bands used by unlicensed devices are 433MHz, 900MHz, and 2.4GHz.  433MHz has very limited uses by the FCC and is mostly used by garage door openers and wireless key entry systems.  Many newer devices are moving to 2.4GHz due to the greater amount of room, althrough 2.4GHz is harder to use and has less range then the same power 900MHz system.
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== Voltage Regulators ==
 
== Voltage Regulators ==
Input to a regulator is a voltage that either varies over time or varies with the load.  The output is a voltage that is constant.  Many voltage regulators also include a current limiter and/or short circuit protection.  They come in two basic varities linear and switching.  Switching regulators are more complicated and expensive, but are also more efficient, and can sometimes have a larger output voltage than the input.
 
 
 
 
{|
 
{|
 
! colspan="2" align="left"| Linear Regulators
 
! colspan="2" align="left"| Linear Regulators
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|}
 
|}
  
See also:
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See [[switching regulator]].
*[[Basic Voltage Regulators]]
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*[[switching regulator]]
 
  
 
== [[555 Timers]] ==
 
== [[555 Timers]] ==
 
[[555 Timers]]
 
[[555 Timers]]

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