Difference between revisions of "Switches"

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*[http://en.wikipedia.org/wiki/Electrical_switch Switch From Wikipedia,the free encyclopedia ( inc. Schematic and Picture )]
 
*[http://en.wikipedia.org/wiki/Electrical_switch Switch From Wikipedia,the free encyclopedia ( inc. Schematic and Picture )]
 
*[http://www.kpsec.freeuk.com/components/switch.htm Switches]
 
*[http://www.kpsec.freeuk.com/components/switch.htm Switches]
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* varc4tb  [[Switch Terminology]] _P_T - SPST - SPDT - DPST - DPDT - 3PDT - ....
  
  
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Links
 
Links
  
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*[[Image:Main-G5Q-14.jpg|69px|Relays]] [[Relays]] - Use these to control large power sources that a microcontroller cannot do alone
 
*[http://en.wikipedia.org/wiki/Relay Relay From Wikipedia, the free encyclopedia]
 
*[http://en.wikipedia.org/wiki/Relay Relay From Wikipedia, the free encyclopedia]
 
*[http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=119 Controlling Big, Mean, Devices]
 
*[http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=119 Controlling Big, Mean, Devices]
 
*[http://www.kpsec.freeuk.com/components/relay.htm Relays]
 
*[http://www.kpsec.freeuk.com/components/relay.htm Relays]
  
== needs cleanup ==
 
 
 
varc4tb
 
[[Switch Terminology]] _P_T - SPST - SPDT - DPST - DPDT - 3PDT - ....
 
 
[[Image:Main-G5Q-14.jpg|69px|Relays]] [[Relays]] - Use these to control large power sources that a microcontroller cannot do alone
 
  
 
[[Category:Components]]
 
[[Category:Components]]

Revision as of 08:00, 25 November 2009

Switch Basics

A switch is often to turn something on or off. In the simplest case it is just a wire that is connected or not. Unplugging an appliance is one way to switch it off. A switch is usually a mechanical device where some sort of handle connects or disconnects conductors inside the switch. Another way of thinking of a switch is that it is like a resistor that sometimes has infinite resistance and sometimes has 0 resistance. A computer keyboard is made of a large number of switches. Some switches stay in the on or off position, others only stay on or off while you switch them, these are called momentary switches. A light switch is normally not momentary, a doorbell switch normally is momentary.

Uses:

  • On Off control
  • Range change, as in a meter
  • Data input

Links


Relays

A Relay is a switch that is turned on and off by an electro-magnet ( actually there are new forms that do not use an electro-magnet ). Like other switching devices it allows a small amount of power to control a large amount of power. A nice feature of relays is that there is no electrical connection between the control circuit and the circuit connected to the switch. ( this is called electrical isolation ). They are often used to let low power digital circuits control normal 110v power in a home.

Uses:

  • Turn on several circuits with one control circuit.
  • Control motors.
  • Isolate a low voltage circuit from power line.
  • Reverse current ( double pole double throw relay )

Links