Questions tagged [capacitive]

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1answer
893 views

Which MCU (Atmel) I can use with QTouch library?

Some MCU have QTouch support - # touch channels implemented as a hardware. Is it true that QTouch library was designed only to work with such MCUs? Can I use it with, for example, 'old' ATmega48? Is ...
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2answers
67 views

Is there any material that obstructs or resists capacitive sensing?

For example, is there any material I can place over a capacitive sensor, or the finger or conductor approaching it, so that the sensor will no longer activate?
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4answers
958 views

Excessive temperature on cheap soldering iron - will series capacitor fix it?

Soldering iron came in a $14 USD kit off eBay. Lots of neat stuff, but the iron became so hot as to badly damage a DIY Kit. After a 2nd chance w/ the same results, it was hacked, Heating element of ...
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1answer
161 views

Trigger capacative button

My washing machine is equipped with a capacitive start button. A "button" is marked with paint on the plastic front and on the backside of the panel there is a spring extruding from the control PCB, ...
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1answer
2k views

What material can I lay over a capacitive touch screen that will still make it work?

So I am trying to build a capacitive touch screen in a table, but since the table is much larger then the touchscreen. I like to put something on top that not only make it easier to clean, but also ...
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0answers
91 views

Touchscreen Sniper [closed]

I was reading today about how capacitive touch works. This article on the Arduino site mentions that with a 40 Megaohm resistor you could detect an untouched "touch" from possibly 24 inches away. My ...
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1answer
458 views

How to calculate inductive and capacitive reactance?

I am studying a project that calculate reactance power. I can measure apparent power, real power and power factor. Therefore I can calculate total reactance power. But I don't know whether it is ...
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1answer
75 views

How can I interface to a capacitive sensor and measure its value with my Netduino?

I've just bought a rain detector, not realizing it is a capacitive sensor (I had assumed it was going to be resistive, as most are). However, being capacitive means it can be sealed so no electrodes ...
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3answers
1k views

Making conductive traces for capacitive touchscreens

This is a follow-up to this question I asked years ago. A short summary: I'm using a head pointer (see my linked question for a photo) with a tip made of plastic, thus non-conductive. The shaft is ...
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1answer
184 views

Capacitive Sensing and Dielectric Coupling

I have a design that uses the MPR121 capacitive sensor. It's a very simple board with 10 "slider electrodes". Standard 2 layer construction with FR4 .063" thick. The board interfaces with a ...
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1answer
1k views

Need help for calculation of this capacitive power supply

Look at this circuit. It's an almost complete capacitive power supply with necessary part. simulate this circuit – Schematic created using CircuitLab I have trouble calculating: the input ...
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1answer
67 views

capacitive power suplply

i have following doubts about capacitive power supply or transformerless power supply... what will be real power drawn, will it be 230 x (current flowing through C1) or 6 x (current flowing through ...
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2answers
1k views

How to do capacitance measurement with high frequency oscillator

There are many types of capacitance sensors. I recently come across moisture sensors which measure the dielectric constants of the materials and correlate them to the water content level. It turns out ...
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1answer
1k views

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

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 ...
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11answers
14k 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 ...
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0answers
994 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
3k 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
3k 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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3answers
20k 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: http://zerocharactersleft.blogspot.in/2011/11/pcb-as-capacitive-...
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1answer
337 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.
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1answer
565 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
162 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 ...
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1answer
670 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 ...
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1answer
1k 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 ...
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1answer
145 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
102 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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1answer
1k 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
175 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
437 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. ...
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1answer
1k 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
2k 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 ...
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2answers
559 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
3k 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
2k 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
892 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
204 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
805 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 ...
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1answer
409 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
24k views

Given a load, how do you calculate whether it is capacitive or inductive?

If the impedance at the load has the form of \$Z = R + jX\$, where \$R\$ and \$X\$ are positive real numbers, then then network is called inductive. If \$Z = R - jX\$, then the network is called ...
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0answers
72 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 ...
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1answer
198 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: EVERLIGHT-...
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2answers
680 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 ...
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0answers
421 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 ...
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1answer
830 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
14k 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
1k 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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2answers
2k 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 ...
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1answer
2k 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 ...
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0answers
964 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
402 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 ...