power problems with ground

i have an lcd hooked up to my arduino uno, it is using the 5v on the arduino, i am trying to hook up a button and i need to use the 3.3v on the arduino, but whenever i put the other ground that i need for the button in, the lcd stops working. i could take out the 3.3v pin and the ground pin would still make the lcd stop working. if i put ether one of them on an external power source they don't work. any solutions.

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criticalduck:
i have an lcd hooked up to my arduino uno, it is using the 5v on the arduino, i am trying to hook up a button and i need to use the 3.3v on the arduino, but whenever i put the other ground that i need for the button in, the lcd stops working. i could take out the 3.3v pin and the ground pin would still make the lcd stop working. if i put ether one of them on an external power source they don't work. any solutions.

the image wont upload correctly but here is the diagram url:

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Pin A5 is directly connected internally to SCL, use a pin besides A5 for button (NOT A4), your button is short circuiting 3.3V directly to GND.

Not to mention why are you trying to use 3.3V for a switch which can only be ON / OFF?
Why not simply use a digitalRead for that on a pin with an internal pull-up?
Then you can just connect the switch to ground, and no need for the external pull-up or the 3.3V connection.

Hi,
Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum".
OR
http://forum.arduino.cc/index.php/topic,148850.0.html.

Thanks.. Tom... :slight_smile: