Logic gate relay equivalent

Thread Starter

Shaneyj

Joined Jul 4, 2017
7
Can logic gate be replicated using simple mechanical relays?
I am trying to find a solution to a switching issue. The logic would be a simple OR gate. But not so simple to implement...
120v
NC door switch.
Wall switch that can be either 3 way or single pole.
Light.
Current wiring method :
2 wire from light to wall switch
2 wire from wall switch to NC door switch
2 wire power in to wall switch

Thanks for any ideas.
 
Confused, a bit.

1. Logic: When door i open or ls witch is "ON"; light is ON?
2. NC meaning --- with the switch not activated the door is closed?

The one improvement I see, off hand, is to make the door switch low voltage, but I don;t know your set-up.

A relay consumes power when activated.

A DC supply might draw 3 W without a load.
 

Thread Starter

Shaneyj

Joined Jul 4, 2017
7
Rudimentary wiring diagram attached.
The NC switch is a door switch. It mounts into a door jamb. When the door is open, the switch is in its shelf position, which closes the contacts to turn on a light.
I also have a wall switch.
I would like to have these two switches operate as a 3 way configuration.
This will allow the door switch to override the wall switch, and vice versa.
What has me stumped is the door switch is a single pole device with one set of contacts.
Adding wire to the light is not ideal, because I would have to cut drywall.
I do have access to the wall switch and can add wire and/or a component adjacent to it if this set up can be realized.

1508040942_shaneyj_839x610.jpg
 

Thread Starter

Shaneyj

Joined Jul 4, 2017
7
How is the switch wired now?
It's wired as shown right now...
Power in to wall switch
Switch leg from wall switch to light
Another switch leg from wall switch to NC door switch
Previously, the wall switch was just a junction box for the NC door switch to the light.
 

GopherT

Joined Nov 23, 2012
8,009
It's wired as shown right now...
Power in to wall switch
Switch leg from wall switch to light
Another switch leg from wall switch to NC door switch
Previously, the wall switch was just a junction box for the NC door switch to the light.

You will never need the light on when the door is closed. So, you want an AND configuration.

If the door is open and the switch is on, the light will be on.
If the door is open and the switch is off, the light will be off


DC5E321A-6B3F-406E-8CA9-646B9C4040C4.jpeg
 

Thread Starter

Shaneyj

Joined Jul 4, 2017
7
You will never need the light on when the door is closed. So, you want an AND configuration.

If the door is open and the switch is on, the light will be on.
If the door is open and the switch is off, the light will be off


View attachment 137304
The goal is to have the option of having the light on when the door is closed...
This is a master bedroom closet.
 
You really don't want an OR, but a 3-way switch (or what they call it in the US), A 3-way switch is an SPDT switch.

So, you need to "convert" the switch that you have into an SPDT switch. That you can do with a relay and source of power.

Insteon and/or UPB may have a "home automation" way of making it work too.
 
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