You might have come to a house where you have two switches controlling the same lightbulb and you wonder how that was done. That’s very easy to know, 2 Single-Pole,Double-Throw (SPDT) switches or in a simple term two, 2-way switches were used.

The  schematic  below shows how the connection is made. You  should  see  clearly  now  why  either switch will reverse the state of the LED from on to off or off to on. This  same  circuit  is  used  in  houses  where  you  have  two  switches  controlling  the  same  lightbulb. Though the  wires  in  a  house  are  much  longer,  and  they but  their  connections  are  still  the  same,  they  could  be  represented with the same basic schematic.

 

 

 

 

 

 

Note:A  schematic  doesn’t  tell  you  exactly  where  to  place the  components.  It  just shows you  how  to  join  them  together. Different  people  use  slightly different  schematic  symbols  to convey the  same  thing.