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Topic: 3 switches, 1 light (Read 324 times) previous topic - next topic



I am brand new to this forum.  I would request help in solving a problem.  For my RV, I would like to install a 12V LED light strip in one of the cabinets, and add a magnetic switch to the door.  The problem is, the cabinet has 3 doors, and I would like to add 3 magnetic switches, so any of them will turn the light on.  It seems the only option would be a custom arduino control board.  Any help or directions would be greatly appreciated.



Oct 07, 2016, 02:39 am Last Edit: Oct 07, 2016, 02:40 am by dave-in-nj
no arduino is needed if all you want is to have the light on when any door is open.
just wire all the switches so they have a common power wire and that the light goes to all the switches.
the light then goes to ground.

just like a car, any door that is opened will turn on the light.
and just like a car, it will not go out until every door is closed


Thank you Dave.  So I can use 3 reed switches and if 2 are open, it won't be a problem?  Assuming I'm taking 3 feeds from the positive and taking 1 to each switch, and if 2 switches are open, it won't double the voltage?


Reed switches (used in e.g. alarm systems) are usually "closed" when a magnet is near.
That means the light will be on if the cabinet is closed :(
Car door and fridge door switches are "open" when the door is closed.


That is correct, I would get a Normally Closed reed switch.


You want a connection to be made when a door is open. This could be done with very very simple SPDT microswitches. One for each door. Join all the grounds, give each switch a line to the power source on the 'up' position contact.

If you could double voltage by simply splitting the same wire, well, I don't know what kind of universe with what kind of laws of physics that'd be.


Oct 07, 2016, 03:33 am Last Edit: Oct 07, 2016, 03:35 am by Wawa
Safer to connect power (+) to the light, and let the switches connect the negative terminal of the light to ground (-). That is how it also is done in car doors (for a reason). Don't forget that inline fuse in the +line, to protect the wiring.

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