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What is the minimal capacitor (capitor type/size/capacity) needed to fool a capacitive touch screen?

Say I want to provide a device (completely batteryless of course, and detached from any human touch) the capability to immitate a touch on a capacitive screen (Galaxy S6 here). I know I just need some ...
5
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10answers
2k views

How to make 1 bit permanent memory circuit?

I would like to make a simple circuit to store or save 1 bit of data. The circuit should be able to remember the state of an LED ( on or off ) even if the supply is disconnected from the circuit. I ...
3
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0answers
61 views

What material can I lay over a capacitive touch screen to block its operation, while still allowing me to see it? [closed]

I own a Kindle Voyage and would like to be able to hold it anywhere, not just along the edges, while reading. So I'm looking for a material that's clear to read through, relatively lightweight, and ...
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1answer
58 views

Simple capacitive proximity/touch sensor problem

I've found one simple schematics for capacitive sensor on electronics-project-design.com, and implemented it as follows: The B? is 9v battery. Sorry for the odd-looking schematics: gschem usability ...
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1answer
59 views

capacitive sensor and wire length

I'm a newbie and I've been playing with the awesome Adafruit CAP1188 capacitive touch gizmo. As long as I keep the length of the wires from the CAP1188 to my copper sticky pads to a couple of feet, ...
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2answers
64 views

How do you measure soil moisture using a capacitive sensor?

There are a number of capacitive moisture sensor designs on the internet, which use the insulated copper pads on a PCB.For example: ...
0
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1answer
38 views

Capacitive sensing between two copper plates

Is it possible to detect touch event and its position coordinates between two copper plates spaced apart by approximately 6-7 centimeters? The space between plates have to be transparent.
0
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1answer
57 views

What sensors can accurately detect size of content in a closed container such as number of pills in a pill box?

I am a DIY enthusiast playing with different sensors and electronics. Recently I've been trying to make a pill box for my grandparents to track their medicine intake. However, I cannot determine ...
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2answers
107 views

Finding the touching angle on a touch-screen?

I am wondering if it is possible to detect from which direction (or at which angle) a human touches a touchscreen. Imagine something like this: Is there any technology out there (e.g. special ...
0
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1answer
35 views

Given the dynamic and static power consumption how does one determine the total power for the capacitive load?

I get that the capacitive load is determined which is also indicated by this question: $$\frac{Power}{Voltage^2 \times frequency} = Capacitive Load$$ However, I am not sure how power (which is ...
3
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1answer
53 views

capacitive touch screen

I am currently trying to build a capacitive touch screen. My end goal is to create a giant track pad/keyboard for my computer. Since abnormally large touch screens are quite pricy I have set out to ...
0
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1answer
33 views

Are capacitive display(s) capable of measuring what fraction of a finger is touched?

I'm really curious to get an answer for this question. Since I don't know the functioning of a capacitive display and Google didn't help me on this issue, I landed here. :) Are capacitive displays ...
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1answer
35 views

Feasibility- Flex Capacitive Touchpad

I'm a student(don't know much on Eagle) working on a project where I need a way of multi-touch finger tracking on flexible material. Will flex pcbs work?
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0answers
52 views

how to realize your op amp is driving capacitive load

I am new to the forum, hope everyone is doing well. As the title stated, I have read some app notes and some website about compensation a capacitive-load-driving and found there are some technique to ...
0
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0answers
28 views

Adding Atmel QTouch to an existing project for an AVR that isn't supoprted by Qtouch Composer

The QTouch Library supports many devices http://www.atmel.com/Images/QTouch_Library_Selection_Guide.xls QTouch Composer, part of Atmel Studio, however, supports only a small subset of those. I've ...
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0answers
78 views

QTouch Matrix ATmega8 issues

After trying a lot on QTouch Matrix for ATmega8,It didn't work for me. So sharing the trouble here. I have taken reference from this beautiful article. Here he had provided a schematic and PCB ...
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1answer
138 views

What are possible reasons for this not to work

I connected a 5V relay to an Arduino. It then opened and closed the relay, which had on a terminal (doesn't matter which one?) a wire that went to an iPhone' screen (with tin foil at the tip). On the ...
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2answers
41 views

Capacitive ECG electrodes and capacitor discharge

I am trying to make ecg electrodes with capacitive coupling. Since my capacitor is only about 10 pF at max and I have to have as low cut-off frequncy as possible, I came up with a circuit like this. ...
4
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1answer
129 views

Inrush current limiter - design questions/review

I am considering to use the inrush current limiting circuit that was suggested in this answer. I have a pretty big capacitive load of about 40000uF to charge. Its a buffer for a GSM modem that needs ...
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1answer
167 views

Capacitor Touch switch with QTouch

I have been working on QTouch Implementation for ATmega32 Micro controller. I have taken reference from here. I'm facing issue with grounding Problem. For debugging process I am displaying the result ...
5
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1answer
119 views

Electric shock from laptop due to capacitive coupling?

If a person touches an exposed wire (the wire has a ground-prong) on the 20V side of a power cable while barefoot, I heard that it is possible to receive a shock of higher than 20V due to capacitive ...
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2answers
204 views

Causes of ringing in a PCB

Im trying to understand the source of ringing at the termination point of a PCB traces before i delve into actually designing a PCB. For example, by 'termination point', I mean a clock signal ...
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2answers
272 views

Insufficient ground supply on my circuit? Ground capacitive foil

I'm playing with a wireless sensor device (with atmega, xbee, and Capacitive sensor (simple foil)) that works fine with the lab power supply but as soon as I try it with AA batteries stops working. ...
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2answers
98 views

Capacitive touch directly above LEDs

I'm trying to make a design where the user can run his/her finger directly over a series of 10 LEDs (covered with 1 mm glass), and the LEDs should glow on/off based on the finger's position. I wish ...
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1answer
94 views

Calculating the voltage out of this particular cap coupled circuit

Before I get to my question, I'll just go over the input and output of the circuit from what I "know". The base of the BJT gets a 20 microsecond pulse that puts the bjt well into saturation and "VOUT" ...
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2answers
146 views

Is a capacitive touch screen safe to use?

I was reading about capacitive touch screens. I understood that your hand picks some current flowing on screen. That sounds alarming. Is it safe to use a capacitive touch screen, since it picks small ...
1
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1answer
129 views

Capacitive touch on off power switch

Is is possible to use capacitive touch as a power switch for an embedded project? Can a microcontroller turn itself off and somehow still monitor an input pin? Or is there a dedicated IC that can ...
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4answers
1k views

Give a RL load, how do you calculate whether if it is capacitive or inductive?

This is a topic which has always confused me. For example, if the impedance at the load has the form of \$Z = R + jX\$, \$R\$, \$X\$ positive real numbers, then then network is called inductive. If ...
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0answers
60 views

Capacitive where is the touch?

I am a newbie in the world of circuits and electronics. But we all started somewhere. I have this idea about a street sign that should be used as an instrument. All most like a Theremin. Touching it ...
0
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1answer
154 views

How can I make a POWER-LED Lamp?

What is the best way to light 10 POWER-LEDs with AC mains (220V)? (I want to make an LED lamp.) Here is more info: I have 10 of these POWER-LEDs: Product Chip: 40x40 mil Chip Brand: ...
4
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2answers
104 views

Choice of sensor for detecting touch (on/off)

I would like to detect a user's touch on a shop window (at a specific area, there would be a 'call to action' marking on the window, i.e. 'touch here') Any sensor to detect this must be contained ...
1
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0answers
120 views

Can I use a capacitive sensor to detect a person proximity without touch?

I only see uses of capacitive sensor to detect touch. But I wonder if I can calibrate a capacitive sensor to detect if a person is close enough, even if the person is not touching it. I intend to use ...
0
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1answer
100 views

Capacitive load at the output for analysis of CMOS cells

This question is very rudimentary one. Please point me to the link if this question has been already asked. In general, when working with simulations and and analyzing the standard cells designed ...
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4answers
4k views

How can I make a fine tipped object emit an electric field similar to that of a human finger?

I've asked this before, but knew less about the tech and didn't word the question properly. I know other people have asked similar questions and knew little, so let me be as specific as possible here: ...
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2answers
256 views

What exactly does a capacitive touch screen need to register input, and how can that signal be produced?

There are active styli out there, and they take 3A or 4A batteries and don't require any wireless connection. How do those emulate human touch? EDIT: I am specifically interested in iPad touch ...
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0answers
213 views

Using AVR with Waveshare capacitive touch keypad

I picked up a Waveshare capacitive touch keypad and am trying to get it to work with a ATmega1284P. I have the KEY1 pin connected to PB2 and the LOAD pin connected to PB3. I also have a HD44780 LCD ...
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2answers
483 views

Making a grounded object capacitive

I am trying to make a copper pipe which is placed in a natural park capacitive. It is placed in the soil meaning that it is already grounded. I am using a basic arduino and their capacitive sensing ...
2
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1answer
646 views

Looking for a transparent conductive spray/paint/ink

I know there are conductive sprays available, but these are strongly coloured due to the metals inside them. I am trying to make a (dry) wooden surface capacitive, but would like to have the feel and ...
1
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0answers
474 views

Split-phase 230VAC transformerless capacitive power supply for 5V@30mA regulated output — series cap?

I'm a hobbyist developing a hybrid power switch (electromagnetic + solid state) for a resistive electric stove (8kW max) top. I have a profoundly autistic, disabled adult in the house and I need a ...
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1answer
196 views

Grounding Plexiglass

I have a sheet of plexiglass that has metal strips (Aluminum) that will be connected through wires to an Arduino. The Arduino is grounded but the metal strips are not. The metal strips will rest on ...
3
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2answers
3k views

Capacitive AC voltage detection

As I understand it, a non-contact voltage tester works by creating a capacitive connection from a power line to ground, via the detection circuit and the operator's hand/body. This connection passes a ...
2
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1answer
247 views

Capacitive sensor circuit

I'm designing a capacitive proximity sensor for detection of human presence. My requirement is that I should be able to detect presence by monitoring change in capacitance at the highest possible ...
2
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2answers
432 views

Transistor selection for 5V LED circuit

I'm having a trouble selecting the proper transistor to switch this LED circuit simulate this circuit – Schematic created using CircuitLab The LEDs are 3.6v at 20 mA. I tried figuring ...
0
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2answers
393 views

ESD protection of capacitive touch doorknob circuit?

This is a follow-up to my question: How can I use a generic doorknob as a capacitive touch sensor? I am now ready to move beyond the proof-of-concept stage, but I have not yet learned of a ...
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1answer
3k views

Glitchy Touchscreen Caused by Charger [closed]

I recently bought a Nexus 4. I had a couple of spare chargers laying around. I used a charger that apparently had an issue exactly like: https://www.youtube.com/watch?v=mrpBTG0a6K8. If I used my own ...
3
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2answers
226 views

What are those black things on the board?

I'm a beginner in electronics, and I'm ignorant of many basic things. Check out these black things on the board: These are from a keyboard. I'm disassembling it and I want to connect my own ...
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1answer
2k views

Water level: BIG capacitive level sensor with steel bars?

So I want to measure water level under a bridge, or inside the city drain. Would it be possible to run two long (4 meter) metal probes, each one enclosed inside a PVC pipe, and placed one next to the ...
3
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3answers
4k views

Simplest touch sensor for a copper surface

I'm looking for the simplest way to implement a binary on|off touch switch using a single pole. The touch surface is copper. The position or pressure of the touch is not needed, just simply: On = ...
3
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2answers
2k views

Designing a Transformerless power supply

I am working on a transformerless PSU for maiking a 3nos.x3 watt led, each having forward voltage around 3.6v and current around 650-700ma. I have worked on this kind of circuit: I guess a 1uf ...
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5answers
15k views

How to use a capacitive touch screen without a human hand

I'm a programmer, and I usually hang out over on stack overflow, but I have a electricity question. I'm trying to interact with an APP on my phone by indirectly touching the the screen. Modern ...