# Creating an xor and xnor gate using only resistors, spdt/spst switches, and red LED d

#### gslime422

Joined Feb 21, 2013
5
Hello I am doing a simple project, where I have to create the logic gates using only the items listed. I have created a not,and,or,nand and nor gate thus far. However I am stuck in creating the xor and xnor gate. I figure I have to use spdt switches, but I do not understand the concept. Thank you

note: this is suppposed to be done in multisim

#### WBahn

Joined Mar 31, 2012
30,290
Think of how the lights in a stairway work where you have a switch at the top and a switch at the bottom. Flipping either switch toggles the state of the light. This is an XOR function. It is known as a "three-way" switch. Look into that.

#### gslime422

Joined Feb 21, 2013
5
yeah i have read about that and understand the idea of an xor gate. basiclly the led should turn on when either of the switches are on, but not when either both of them are on/off. I just have no clue how to set up resistors and spdt switches to turn on this dang red LED in multisim

#### WBahn

Joined Mar 31, 2012
30,290
Look up how a hallway or stairwell light is wired in a house.

#### gslime422

Joined Feb 21, 2013
5
Okay so I would need two power sources? I'm not sure if I'm reading the descriptions right.

#### WBahn

Joined Mar 31, 2012
30,290
Why would you need two power sources?

Could you please provide a diagram of what you are thinking about? Also, provide a diagram for one of the circuits you have already done, say the NAND, so that we can use it as a basis for discussion.

#### gslime422

Joined Feb 21, 2013
5
okay heres my nand i did on multisim. And i meant resistors * not power supply, sorry about that.

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#### WBahn

Joined Mar 31, 2012
30,290
Okay, now draw the circuit for a three-way switched light.

#### gslime422

Joined Feb 21, 2013
5
heres my attempt at an XOR, although the best I could come up with is pretty much an OR gate. i don't really understand how to use the single pull double throw switches. Am i getting the right components? Is there anything I need to add/remove?

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#### WBahn

Joined Mar 31, 2012
30,290
Have you looked up three-way switches? Do a Google search for "three-way switch" and look at the dozens of images that come up.