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Need some help

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Tadass

New Member
Hello, all engineers and technicians.
I have a problem whitch i cant solve.
I want to connect a wire to a touchscreen android phone and simulate a click with a relay. I had this done wrapping end of a wire in aluminium foil and taping it to the screen connecting it tothe relay and from the relay to the positive of the cicuit board. Everything worked fine, but now i have a samsung galaxy s5 and it doesnt work anymore and it seems nothing works. Do any of you have any ideas how to make it work?
 

Tadass

New Member
Its a school project i want to turn the cell phone on and let it click one thing but it has to work with a relay this is the best way and the older phone has some system problems witch made it useles
 

dknguyen

Well-Known Member
Most Helpful Member
Where was the power for this coming from?

You taped the aluminum foil to the screen? And covered it up??

???
 

dknguyen

Well-Known Member
Most Helpful Member
Drawing a picture or something. It's really difficult to tell what you're talking about since it sounds like you're leaving something out or thought you said something but didn't. Because it sounds to me like you could just tape a momentary switch onto the phone and run wires out of it. I also don't understand why the phone itself matters since it just sounds like you're sticking things onto the phone rather than doing anything with the phone itself.
 

Tadass

New Member
This is the idea. I only wonder what
Im doing wrong because it doesnt work. If you need a picture i can make it after work.
 

dknguyen

Well-Known Member
Most Helpful Member
Ohhhh. Okay. I see.

So the bare end of a wire is in contact with a touchscreen, and the opposite end is connected to the primary contact on a relay which connects to a positive power supply, and when the relay closes, the charge sent down the wire is supposed to simulate a finger touching the screen in that area?

I don't know too much about touchscreens but is it possible that the newer touchscreen is programmed to reject anything that is too different from the conductivity or charge of a human finger? Maybe try adjusting the positive voltage you are using? Or reverse the polarity?

Does it work any better if YOU are the one physically holding the opposite end of the wire rather than it being connected to a power supply?'

EDIT: I tried this using a a piece of metal to swipe my phone:
1. If I am touching the piece of metal, I can use it to swipe.
2. If I recently touched the piece of metal but then hold it with an insulator, I can still use it to swipe.
3. If I continue to hold the piece of metal with an insulator but then drain the charge from it (by touching it to the screw on a lightswitch on the wall), I cannot swipe with it until I physically touch it again with my skin.

Unfortunately I don't have a battery handy so I can't do something like applying a charge to the piece of metal that isn't my own to see if it still works, or if the phone ignores it because the charge is too different from my finger. You might want to try that on your end (or just mess around with the voltages on your setup).
 
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dknguyen

Well-Known Member
Most Helpful Member
Test it holding the other end of the wire directly. Then test it with the relay closed holding the other terminal of the relay. If holding the wire works but holding the relay doesn't then the relay is the problem

You did not use the relay to control something else did you? Using relay or switches to conduct high currents (wet switching) produces oxide deposits on the contacts from arcing when they open. This layer can be punched through by high voltages or currents(aka power). But if the relay or switch is used after being wet switched to conduct voltage but almost no current (dry switching, aka a voltage only signal) then the signal might not be able to get through the oxide layer.
 

Tadass

New Member
Thanks a lot for your help. The relay is okay and working i tried sticking it to the screen like i did on the older phone and i touched with finger and tried positive and negative wires and other stuff it looks like it doesnt work. i saw another video on youtube called "stupid games call for stupid cheats" and they are doing the same thing also with coins i really wonder is there a reason maybe why they are using coins?
 

dknguyen

Well-Known Member
Most Helpful Member
Well, tin foil is kinda crappy, wrinkles easily, and doesn't lay flat so that's reason enough to use coins.

So even holding one end of a wire in your finger and poking the other end of the wire to the screen doesn't work on the newer phone? I'm not sure what to tell you there because seems to me like that should work. It certainly did on my phone. Does holding a sewing needle in your hand and touching the screen work?
 

Tadass

New Member
The needle doesnt work, i think too small surface area. When i place the foil on my screen it works, like i can swipe and click without making any contact with the foil. but if i hold it steady at one place an touch the foil to create a click it doesnt work.
 

dknguyen

Well-Known Member
Most Helpful Member
The samsung Galaxy S5 has multi-touch. Did your old phone have multi-touch?
 

Tadass

New Member
No it didnt have multi touch, but i found something out if i unlock the phone and touch the other end of the wire its working but after a time it stops working
 

dknguyen

Well-Known Member
Most Helpful Member
I was thinking maybe the multi-touch implementation is more sensitive or picky about something.

How long is the wire?

No it didnt have multi touch, but i found something out if i unlock the phone and touch the other end of the wire its working but after a time it stops working
Isn't this just the test I asked you to do post in #9?
 

Tadass

New Member
Yes i tried the test before but it wasnt working, now it works sometimes and stops after some clicks
 

dknguyen

Well-Known Member
Most Helpful Member
So if you hold the wire and touch the other end to the screen, it stops after you click enough?

What if you do a continuous hold? Does it automatically release on it's own after a period of time?

What does it take to get it working again? Leaving the piece of wire alone for some time? Touching the ends to each other? Touching the wire (or maybe yourself?) to ground (i.e. the screw on a lightswitch or electrical outlet?).
 

Tadass

New Member
I try ti figure it out by trying everything but it looks like the phone randomly decides if it lets it work or not, and it never worked with relay really no idea why i have tried multiple relays mechanical ones and solid state and even if i touch it tot the positive and after conneft it to relay and switch relay on and of it never worked not even once
 

dknguyen

Well-Known Member
Most Helpful Member
Have you tried different size contact areas vs different voltages? Maybe it requires each to match the other.
 

Tadass

New Member
I tried from very big to very smal i think abou 6 or 7mm size works the best but i think it matters what happens on the end of the wire because i have 2 wires of a relay already set steady so i can test really quick. One wire is already wire to the positive and the other one is free. When i touch the positive lead at the connection with the relay it works and after 0.5 sec i connect it to other lead of the relay and let it go off and it doesnt work. The relay is perfectly fine and it works. But i never get a click. Even if i do it manually toucht the relay cable connections one to another it doesnt work anymore
 
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