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  • Author Author: tariq.ahmad
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The Learning Circuit 45: How Three-Way Switch Circuits Work

How 3-way Switch Circuits Work

The Learning Circuit | element14 presents |  Project Videos

 

 

Many homes have lights that can be turned on by more than one switch. Karen goes over how these switches work and how to wire one into your project circuit.

 

 

 

 

 

 

Bill of Material:

 

Part

Toggle Switch, On-On, SPDT

Multicomp1Buy NowBuy Now

LAMP HOLDER, MES SCREW, PK10

SLI VCH1Buy NowBuy Now
Incandescent Lamp, 3.7 V, Miniature ScrewMulticomp1Buy NowBuy Now
Test Lead Set, Alligator Clip to Alligator Clip, 10pkMUELLER ELECTRIC1Buy NowBuy Now
Slide Switch, SPDT, Through Hole, VerticalEOZ1Buy NowBuy Now
Hook Up Wire, Red, 22 AWG, 25 ft, solidNTE ELECTRONICS1Buy NowBuy Now
1K ohm resistor, 1/2WNTE ELECTRONICS1Buy NowBuy Now
Battery Holder, AA x 1, Wire LeadsKeystone1Buy NowBuy Now

 

Additional Parts:

 

Product Name

Standard SPST wall toggle switch

(2) SPDT paddle wall switch

 



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  • Hi Karen,

     

    Very nice presentation of the 3-Way switch configuration. At the very end your explanation of the position of the toggle with respect to the closed contacts was correct but the position of the slide switch with respect to the closed contacts is actually the opposite from what you indicated. The contact follows the slide and this means that the closed contact is always on the same side as the slider.

     

    John

  • in reply to jw0752

    I'm not sure that you're right for this particular switch. Here's a clip from the data sheet. Unless I'm reading it wrong, A is on when 1-2 are connected and B is on when 1-3 are connected. Those pins are on the opposite side of the slide position.

Comment
  • in reply to jw0752

    I'm not sure that you're right for this particular switch. Here's a clip from the data sheet. Unless I'm reading it wrong, A is on when 1-2 are connected and B is on when 1-3 are connected. Those pins are on the opposite side of the slide position.

Children
  • in reply to makerkaren

    Hi Karen,

    This is of course possible but it is contrary to traditional function of slide switches. I saw you had one of these switches. Why not take an ohm meter and verify the position for confirmation. I would be fascinated to see the physics of the internal contacts if you are correct.

    John