Need some help

[Tadass]

I wil try to make a video

 

[Tadass]

The video is too long to upload but what happens is i unlock the phone and touch with the wire with my finger it clicks. I touch the wire to a positive pole whitch is also connected to a relay and it also clicks. I have another cable comming out of the other connection of the relay whitch is normaly open so it doesnt make any contact with the positive yet and it just begins to click crazy fast maybe 15 times and then stops and as soon as power the relay it doesnt work. And the relay cables still attached i touch the connection directly to the positive pole and it also doesnt work. But when i disconnect from the relay is starts to work again. Ive tried this with multiple relays and different lenghts of cable but the result is the same

 

[dknguyen]

I can't follow what you are saying. Making a drawing for each situation you are talking about.

You aren't clear enough. Typical relays have 5 connections and I do not know which ones you are referring to when you say something is connected or disconnected. I don't know what you're applying power to and what you're not applying power to. I also thought we were talking about clicking the touchscreen but you said "clicks crazy fast" which makes me think you're talking about the sound of the relay clicking.

 

[Tadass]

First i try to toich nr1 with my finger and it works. then i try to touch nr1- nr2 and it also works. Then i connect nr1 to nr 3 whitch is normaly open so it is not making contact and then the phone clicks like 15 times crazy fast. (Im using the number dial buttons to test when it clicks) and after it just stops. Then i power the relay and it doesnt click. And as last i try nr1 and nr3 still connected to touch nr 2 but is also dont work. Then i disconect nr1 and nr3 and toich nr1 to nr 3 and it works again.
Ps there relaysbim using are small solid state relays they have only positive and negative and the to connectors

 

[dknguyen]

Oh these are solid state relays? I thought you were using mechanical relays. That's a big piece of info. Have you always used SSRs for this? Or have you tried mechanical relays at some point and it still did not work?

I'm guessing the 15 fast clicks is due to the parasitic capacitance inside the SSR, and after the capacitor equalizes then the clicking stops. A mechanical relay doesn't have this so I would not expect this to happen with a mechanical relay.

Give me the part number for the SSR. I think some SSRs (depending on how they are built) have minimum voltages and currents before they truly conduct.

 

[rjenkinsgb]

You do not need a power source for the screen contacts and having one may be confusing things.

The screen works by capacitance to (the phone) "ground" - the other side of the circuits could be a literal connection to the phone USB ground, headphone ground etc., of just another large piece of foil stuck to the back of the phone as a capacitive common connection.

The wires from the small screen contacts need to be short and have minimal capacitance to anything else, to guarantee a large enough change for the relay closure to be reliably detected.
In other words keep those wires well apart and the relays as close to the phone as possible.

 

[Tadass]

Thanks a lot guys. I have one more question is it maybe possible to create something like a circuit board whitch can create some kind of pulse or shock so i could use long cables? I think that would also be a lot more reliable.

 

[dknguyen]

Thanks a lot guys. I have one more question is it maybe possible to create something like a circuit board whitch can create some kind of pulse or shock so i could use long cables? I think that would also be a lot more reliable.

Wouldn't you have to take the opposite approach? Creating a circuit with short leads to the phone that buffers the phone from the very long wires running away from the phone?

Did it work when you cleaned up and shortened the cables?

 

[Tadass]

I havent tried that one yet i will try to shorten the cables and place the relay directly next to the phone i will let you know when i have tried it. Was very busy today so i had no time to try today

 

[Tadass]

I tried shortening the cableb to about 8 centimetets and put a mechanical relay next to it. The other connection i tried connecting the usb cable from the phone and also the positive and negative of the circuitboard where the relay is on an noothing works. Im really out of ideas now☹

 

[rjenkinsgb]

Do you have the other side of the relay contact either directly or capacitively grounded to the phone body? Try laying the phone on a large piece of foil and use that as the "ground" side.

The touchscreen works by sensing current drain on an AC signal, when something with sufficiently large capacitance to draw power touches the screen.
The screen contacts need to be sticky or pressed firmly to the screen and then connected to phone "ground" to trigger inputs.

- Imagine you are holding the phone, you are emulating the path from a fingertip to the hand with the phone in it.

 

[Tadass]

Okay that was the trick i guess because its now working perfectly with the relay. I put the phone on a big piece of foil. It works perfect but if i dont power the relay and dont create a click for the first maybe 15 sec it wont click anymore but when i do it right after its unlocked it works perfectly and very reliable always when i power the relay i get a very nice click. thank you guys you really helped me out now i can go on and test further and try whats works best.

 

[dknguyen]

Do you have the other side of the relay contact either directly or capacitively grounded to the phone body? Try laying the phone on a large piece of foil and use that as the "ground" side.

The touchscreen works by sensing current drain on an AC signal, when something with sufficiently large capacitance to draw power touches the screen.
The screen contacts need to be sticky or pressed firmly to the screen and then connected to phone "ground" to trigger inputs.

- Imagine you are holding the phone, you are emulating the path from a fingertip to the hand with the phone in it.

I was thinking about this but then discounted it I remember when my girlfriend used to put the phone flat on a table to play a tapping game where she would use fingers on both fingers to tap, as well as phones that are in cases. Sometimes double or triple layered cases. What's going on there?

 

[rjenkinsgb]

I was thinking about this but then discounted it I remember when my girlfriend used to put the phone flat on a table to play a tapping game where she would use fingers on both fingers to tap, as well as phones that are in cases. Sometimes double or triple layered cases. What's going on there?

The human body has a relatively large capacitance and can easily "load" the touchscreen sensor system without a direct ground connection / return path.

A few inches of wire does not have the same effect and needs a more substantial signal path back to the phone.