Interacting with touchscreen (iPad)

Other Hardware General Electronics
1

Hi, all
Ok, I’m brand new to this and also I’m Swedish :slight_smile: So bare with me and please rospond as if my IQ were in the double digits.

I have an Arduino UNO, a breadboard some miscellaneous components and a couple of relays and have managed to set up a simple circuit switching between lighting two LEDs depending on if the relay in use is open or closed. So far so good. But I’m trying to accomplish some interaction with a touchscreen (iPad) and I found this project somewhat similar to what I want to do: http://www.instructables.com/id/Arduino-Plays-Piano-Tiles/

They seem to manage to “touch” the screen using relays, some coins and ground. Since this is 2016 and I haven’t used cash money in a couple of years (so no coins) I thought I instead might use some spent 9mm brass that I soldered a cable to. When I simply place the empty shell on the screen no touch is registered but when I touch the shell or the other end of the cable a touch is registered. This small experiment led me to believe that the brass might work.

Here is my problem: no matter where I connect the cable to the breadboard it registers as a touch on the screen. I’ve tried ground, vcc and somewhere in the middle of the breadboard not connected to anything.
Additionally, iPad is placed laying directly on a table, common on the relay is connected to ground on the breadboard (have tried vcc there as well).

How should i proceed with un-touching the screen once wire is connected to board?

2

the iPad screen is a capacitive touch screen, and the copper doesn't have an electric field, you body does, so when you touch screen some of your electricity is transferred to the iPads screen, and it registers...

I recommend getting a few of those stylus pens for iPads and use them instead of the copper.

3

Thanks for the reply but I'm not sure I get it fully. Firstly as it is now it registers touch, I can't get it to not register touch once the brass is connected to the breadboard which in turn is connected to the Arduino.

Also I thought it was the other way around and that the body absorbs some of the electricity on a touch screen and that was what registered as a touch and that would be why grounding something metallic touching the screen would have a similar effect. But you are saying that a small current needs to be transfered to the screen instead? Since it's constantly touching now does that mean there somehow is enough current everywhere in the breadboard?

Would a stylus pen work with the relays or would I need some other device to move the stylus up and down to touch the screen like a solenoid or a servo of some sort?