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10

No. The edges of a resistive touch overlay are important. They carry the conductors that connect to the resistive layers. Those white traces around the edge are conductors, and are necessary for the overlay to work. If you look carefully, you can actually see which wire corresponds to which axis and side. Keep in mind that you can always use an overlay ...


6

If you're really after a capacitive touch sensor, this likely won't work at all because the aluminum plate is a short to ground. You're better off making an oscillator (ring or 555 based oscillator's are my favorites) that has a frequency based on R and C where C is two separate contacts where the touch sensor goes. A persons finger near the two contacts ...


5

With that many active zones, you're going to want to think about matrix methods rather than completely individual electrodes. Here's a relevant application note from Freescale: Designing Touch Sensing Electrodes


4

You can create a very simple touch switch using only the 555 timer by connecting the aluminum plate directly to the trigger: The downside to this version is that if your plate is too big, it can act as an antenna and the output will be very unstable. Additional circuitry can be used to filter out the noise if desired.


4

Trackpads generally come in two flavors. PS/2 and USB. A few can come in direct/analog mode, but those are very hard to find. From the age of it, it's probably PS/2. 5v VCC, Gnd, A Data and a Clock pin. VCC and Ground should be easy to find. The other two are slightly harder. Basically you will have to use a multimeter to narrow it down, then guess. See ...


4

The normal process for applying ITO is vapor deposition: like 'fogging' a mirror with steam, but using a boiling metal alloy. The challenge in doing that with thermoplastic would be not melting it in the process. (There are some references on google to doing this at room temperature with a plasma instead, though). Recent advances in glass hardness mean that ...


3

A step-by-step look at how PixelSense works: A contact (finger/blob/tag/object) is placed on the display IR back light unit provides light (though the optical sheets, LCD and protection glass) that hits the contact. Light reflected back from the contact is seen by the integrated sensors Sensors convert the light signal into an electrical signal/...


3

If the laptop worked you might want to plug it in and plug a logic analyzer or an oscilloscope to the pins of it to snoop what sort of information it's sending. Even if you can't plug it back in the laptop, if you can figure out the power supply voltage and pins it might start sending data even without an external clock signal. Here's a link that might be ...


3

This is most likely a capacitive touch interface. This by making use of the rule that all circuit elements have some amount of capacitance, be it a capacitor a resistor or even a piece of wire. The capacitance of these pieces is also weakly affected by certain materials, usually somewhat conductive themselves such as pieces of metal, wires or you. There ...


3

The capacitive sense controller is measuring capacitance. However, it may not be so obvious to what it is measuring capacitance to. There are at least two broad systems, capacitance to ambient, and mutual capacitance. In the first, your finger makes a larger capacitive connection back to the circuit's own ground. This is connected to real ground in the ...


3

Most probably this is a resistive touchscreen, as one would expect in a non-consumer appliance. Looking at service manual, on page 29 they suggest a non-abrasive pointer for calibration. Since no additional material requirements are given, it is clearly not capacitive or SAW. Resistive touchscreens are quite easy to use with an ordinary MCU, and it only ...


3

Hi Z stands for "seemingly almost nothing connected", it acts as an open circuit, so you should take care of that situation if you want the other circuit to function properly. Also, by the looks of it, 4.7k seems to be right in this scenario, as it would mean ~1mA at 5V, which is usually tolerable by most of the devices. You should take a look at the uC ...


2

You might also consider measuring diameter using a linear encoder, which would add precision and accuracy at the cost of...cost. Or you could even go about it like digital calipers do - a mechanism based on varying capacitive and measuring phase shift of PWM signals (i.e. probably more complicated than is worthwhile). But, better yet, use a slide pot, ...


1

simulate this circuit – Schematic created using CircuitLab 300mV deflection at 2/3 FSR rating for load from 2/3 to 1 x FSR rating ? Static load is probably quasi static, so dynamic touch will be problematic so DC tracking by AC amplification Some problems with OEM specs at 10k expecting 2.5V at 50% FSR but only seeing 20% on left. batch to batch ...


1

You probably won't be able to measure the change in capacitance between the strips being pressed together and not being pressed together, as it will be small, but it's still there. (I would guess that their self and mutual capacitance to be in the range of 0.1-10pF.) A capacitor changes voltage by gaining or losing charge. They lose charge constantly to ...


1

that's a nice question! I've got an Idea, which might help. You can use an ultrasonic sensor, and place them in front of a board, based on how large you want it to be. Measure the distance between the board and the sensor(serial.print and then take 5-6 values get an average figure). Put an object now, and subtract this reading from the initial distance(...


1

223 touch has an option to set between active high or active low mode so you can skip transistor.


1

You're probably right... It's very likely a capacitive keyswitch body. The 4 pins are DC power (2x) and a floating output (typically the collector and emitter of an NPN). The sponge (which isn't graphite) conducts the electric field lines down to the electrode (plate) in the well of keyswitch body. This particular part must be old or custom as I couldn't ...


1

A capacitive touch screen measures capacity/resonant frequency of "flat plate" senslrs spread across the screen. Your finger touching the screen actually doesn't cause current to flow (that would be a resistive touch screen), but changes the capacitance between 2 microscopic plates. There are many thousands (actually, several millions on modern displays) of ...


1

You can use QTouch also on MCUs which do not have dedicated touch controller peripheral attached to it. Although there will be some limitations like only one single sensing method can run at a time. Also, it will consume more CPU time and more power. Check out Atmel's site: http://www.atmel.com/products/touchsolutions/bsw/touch-support-for-mcus.aspx For ...


1

What are you testing ? Assuming the touchscreen performance; you should use a camera in the anechoic chamber and use an artificial hand to touch the screen and observe the performance. I don't know the product standard exactly but as an EMC engineer thats how I would perform the test. edit:spelling mistake


1

A cap sense button, with a thin layer of plexiglass above it, would work just fine. Cap sense does not require exposed copper, and some times not even direct touch, with some examples having a slight air gap.


1

Membrane switches are probably your best bet. You might be able to salvage them from an existing keyboard - such as the ones on microwave ovens or other kitchen appliances. Piezo crystals generate analog voltages - more voltage if hit harder. I suspect that interfacing might be a little more complicated than contact switches. Both are momentary switches (i....


1

You can create the capacitive sensors on the PCB itself right under the areas of interest. A filled circle with surrounding ground plane will form a capacitance you can measure. A lot of MCUs have a capacitive touch function built in, but you can also get away with just a timer and a GPIO pin. You can get not so bad results quite quickly, but outside of the ...


1

Yes, this is commonly done with capacitive sensing, often referred to as cap touch or cap sense. This is a deep subject, way too complicated and with too many details and pitfalls you really need to know about to get into here. Most of the major microcontroller vendors have numerous app notes, sample code, working subsystems, and evaluation boards. ...


1

Any capacitive touch sensor will work for this. Most vendors have dedicated ICs for exactly this application. You could even get away without a dedicated sensor if you used a MCU with built-in touch capability and an appropriate library, such as pairing Atmel's AVR chips with their QTouch library.


1

A bit of hunting finds that it's a TouchSensor TS-100.


1

Even the twitchiest gamer won't be able to distinguish 1ms so the controller does not need to measure that frequently or respond that quickly. Resistors have an inherent time constant because of parasitic reactance but it will be much faster than 1ms for a modest size touch screen. The mechanical touching and the controller response time are another ...


1

Hi Z is abbreviation for High Impedance (Z). Dont forget to use interrupt for touch detection.


1

The surface is a vision based system that UI you see is actually projected from below and it's using infrared cameras below the glass to detect touch, objects and those scanned documents you see. http://msdn.microsoft.com/en-us/library/ee804823(v=surface.10).aspx


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