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What are the components required for a paper circuit for transmitting data to android mobile?

Harihara Krishnan

Mar 3, 2017
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Mar 3, 2017
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Basically I am a software developer and I am new to electronics. Consider that a paper have different touch points drawn with a graphite / pencil and I would like to transmit the touch points' codes / values to an android mobile application. And I have an android app which runs a thread with a timer. I need to match the exact time position in a thread and touch time on my paper circuit.

I need to know the basic components required to collect different code values of each touch point in my paper circuit and transmit the value to the android application instantly where my application can compare whether the user action is matched with the automated timer logic.

I simply tried a paper circuit by lighting an LED with a power supply by referring this video link Also this video too. If possible I can use wifi to transmit the value to my android app. Few of my friends suggested to use Bluetooth. I need to know first whether on touch we can enable some point in a pcb circuit to transmit some defined code value. (pls see the video)

Also I would like to know how the keys in that DIY paper circuit midi keyboard works? how the program captures each key and play different sounds accordingly?


Kindly suggest your ideas. If anyone can provide some basic circuit examples I will be more grateful.

Best regards, Harihara Krishnan
 

donkey

Feb 26, 2011
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Feb 26, 2011
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ok so the best version of a graphene circuit I saw was a mouse pad.
so the idea is
A) graphene has a defined voltage drop (not defined unless applied evenly though)
b) between 2 points you can see where a "jumper" has occurred as the voltage is changed
C) using the 4 points will give a reference to where you are

it sounds simple but I SUPER suck at programming. so have never really gotten that far into it.
 

Alec_t

Jul 7, 2015
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The principle of operation of the touchpad is that of a potentiometer, with your finger acting as the wiper to pick off a fraction of the voltage applied between corners of the resistive sheet defined by the graphite layer.
Problems include
1) non-uniformity of the layer,
2) wear and tear of the layer,
3) interference picked up by your body acting as an antenna.
If you can tolerate or overcome those problems then you would need to buffer the picked-off voltage with a high input impedance op-amp and convert the voltage to a digital value.
As for the MIDI keyboard application, the presence or absence of a finger could be used to switch a CMOS logic gate (one gate per 'key'). Filtering (in the analogue or digital domain) to reject interference would be needed. The gate output states would be coded into MIDI note on/off commands.
 
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