Basic Question - Adding an on/off switch with wall wart power?

I'm building a project that will be powered by a wall wart, but I don't want it to be on at all times. I'd also prefer not to have to plug in the cord everytime I want to turn it on (I may even hide the cord inside a wall).

So - simple question: Is there a way to wire a SPST Push-On/Off switch to the arduino to shut it on and off?

I found this in another thread... would this work? Basically switching it from external to USB (and since the USB wouldn't be plugged in, it would essentially turn it off)? Or would it have to be a slide switch and not a SPST push-on/off?

Wire the common to the pin in the center of the header that has the jumper for USB or External power. Wire up one connection to the USB power power pin and one to the external power pin. Now you can flip the switch to use USB or external power or be off. I'm not sure but I think a three pin connector similar to the ones used on the board would allow you to solder to the connector and slide that onto the three pins on the board.

Or is there another way to essentially add a power switch to the Arduino board? Any help you can offer would be greatly appreciated.

(and since the USB wouldn't be plugged in, it would essentially turn it off)?

Yes, however the wall wart will still be powered and using energy even though nothing drawing power from it.

Ok, so pardon my noobness but I can’t seem to find which header it is on the Uno. Is it the three pin one to the left of the AC female plug? The SPST Push-On/Off only has two prongs, so would I need to get another type of switch, or how would I wire it up correctly?

I can't seem to find which header it is on the Uno

There is not one on the Uno, this was a version of the arduino they stopped making over three years ago.

The SPST Push-On/Off only has two prongs, so would I need to get another type of switch

No. Wire up the positive out of the wall wart to one prong, take the other prong and wire it to the Vin pin. Wire the negative from the wall wart to the ground pin of the arduino.

I'm building a project that will be powered by a wall wart, but I don't want it to be on at all times.

I'm surprised that Mike didn't point out that in much of the civilized world the power receptacles have switches.

Don