Questions tagged [capacitive]

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Why are parasitic capacitances the main factor for limiting high frequency performance of active devices such as transistors?

According to the Wikipedia article, the reason for the limit of frequencies in which transistors operate is the parasitic capacitance. But I don't understand why this is so. Wikipedia article: ...
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42 views

Failed to trigger capacitive touchscreen of my iPhone XS

As you can see in the title, I am trying to trigger the capacitive touchscreen of my iPhone XS but it does not work as intended. Here first a picture of my Arduino setup (the cardboard represent my ...
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2answers
63 views

Finding the kVA loading after improving the power factor

This is a homework question I've been attempting. But the answer I get doesn't match with whats given and I don't understand why my method is wrong. This is the question with answers. Here's what I'...
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1answer
44 views

Capacitive Touch Faucet Solenoid Battery Box vs AC/DC adapter [closed]

I have a MSTJRY touch kitchen faucet purchased through Amazon. It uses a valve solenoid in line with the water supply to control the on/off of the faucet based on capacitive touch on the faucet stem. ...
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40 views

TTP223 capacitive sensor on USB switch takes two presses to work

I'm trying to solder a TTP223 capacitive touch sensor to a USB switch (specifically a "UGREEN USB 3.0 Switch, 2 In 4 Output") to rig a sort of capacitive KVM switch to a desk PC I'm building,...
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1answer
90 views

How to properly drive parallel analog switches (variable capacitive loads) with opamp(s)?

So as you can see I have 16 SPDT switches on one side of my 16 'RUT paths' and 16 SPDTs on the other side. Each SPDT(ADG1434) has two source pins (SXA and SXB) and a common drain pin (DX), 'X' ...
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1answer
40 views

Capacitive touch sense problem with battery powered laptop

I designed a PCB that includes capacitive touch. The circuit works with 5V powered from USB. When Laptop is connected to 220V line, the PIC can sense capacitance variation. When Laptop is not ...
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0answers
27 views

Capacitive Touch Pad Design with TTP224 ic

I am designing circular capacitive touch pads of Dia:20mm driving from TTP224 IC on my PCB. There will be 2mm glass panel above Touch pads. My PCB contains other circuits like Arduino, Antenna bands ...
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2answers
76 views

How to make sure that my compensated attenuator would work for certain pulse widths?

I have an input (one-shot) pulse that has to be attenuated by 1/2 (half). The input pulse would be of variable width in between 1us and 100ms and would have a variable amplitude: one voltage level ...
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1answer
22 views

Test device for capacitive touch screens?

Are there any (more or less) simple test devices for capacitive touch screens, e.g. something which I can attach to a touch screen and which is able to do capacitive inputs at fixed locations (ideally,...
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1answer
118 views

Reverse-engineer pinout of capacitive touchscreen

I'm interested in reusing the capacitive touchscreen of my old iPad. (As a learning experience -- I'm aware that this project will cost me more than just buying a new capacitive touchscreen would.) ...
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39 views

Variac and Other dropper in line

I have a beautiful old variac, with a sliding (rotating) center contact. I would love to use this on a nice LED string inside a glass bulb on top of the device. But also, use the variac as the dimmer, ...
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23 views

Distribution of charges in an electrostatic study

I have a question concerning the capacitive coupling between two conductors. The capacitance C between the two is only a function of the diameter of the 2 studied conductors, the insulation thickness ...
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0answers
25 views

How to improve capactive sensor when there is a floating local ground [duplicate]

I am using a microchip MTCH101 IC as a proximity detector (based on a self-capacitance electrode) and i have some trouble in detection because of a floating local ground (i guess). The sensor is power ...
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2answers
120 views

ESP32 touch sensor outputs unstable values

I am trying to implement touch functionality of esp32 development board to toggle a led. But on uploading a simple touch detection sketch, output have spikes i.e. usually value remains near 100 but ...
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1answer
38 views

Capacitive medium range sensor with STM8

I am trying to replicate the behaviour of this library: https://playground.arduino.cc/Main/CapacitiveSensor/ with an STM8, but I am not able to do it. I want to detect the proximity of the human hand ...
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0answers
55 views

Waterproof capacitive touch-sensor issue

my goal is to develop a waterproof capacitive touch-sensor. In many sources on the internet, it is said that a mutual-capacitance sensor can achieve this. For example, in the TI Designs: TIDM-1021 ...
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115 views

What material can I use to block a capacitive touch from registering?

I am a self proclaimed tinkering problem solver, but this one has me absolutely stumped! I have a capacitive touch switch panel with six touch areas that close or open a relay to supply power to ...
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3answers
157 views

How to make fast (low latency) capacitive touch buttons

I'm looking to create low latency capacitive touch buttons for a musical instrument. The response time (from physical touch to touch registered in microcontroller) needs to be around ~2ms or less. ...
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1answer
56 views

How is this LCD controlled?

Source: https://ozhealth.com.sg/product/genial-digital-thermometer-t15-orange/ I tore down a digital thermometer today (a Genial T15), and the interface to the LCD caught my eye: although there were ...
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1answer
68 views

Why isn't capacitive coupling considered in EMC testing?

It seems like the emissions of interest in EMC testing are radiated and conducted emissions. Is this because capacitive coupling is so weak it doesn't pose a threat to other devices?
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6answers
3k views

What is Capacitive Loading (Intuitive understanding)

I have read about capacitive loading. But what does it actually mean like intuitively? Just asked this question so as to get an intuitive answer and also know what should I understand when one says ...
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5answers
92 views

Capacitive Switch To Distinguish Between Metal and Plastic

I have an application where a rotating plastic wheel has ferromagnetic inserts on the circumference of the plastic wheel (they don't stick out). Shown below in the picture is the plastic wheel (black)...
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1answer
37 views

Question Regarding Capacitive Sensor IC

I have this Capacitive Sensor IC I am trying to understand and analyze how to use this IC. In the datasheet, on page 13 - Function description, it is mentioned as "There are four selectable non-...
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1answer
89 views

Question about capacitive sensor designs with direct touch to copper or aluminum

I've seen some DIY capacitive touch sensor projects where the sensors themselves are strips of aluminum or copper soldered to a non-grounded wire, where the user touches these strips directly with ...
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1answer
98 views

A hole in middle of a capacitive touch screen

I'm thinking about using a capacitive touch screen (the touch layer only, no display) to detect the position of two moving parts. Each part would have its 'stylus' just above the screen to mark the ...
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4answers
87 views

Analog circuitry for measuring capacitive touch

I'm interested in adding capacitive touch input to a project I'm working on. Ideally I would like a tapered shape so that a finger can slide up as if it's a mixing desk fader or something like that. ...
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0answers
37 views

Is there definitive documentation regarding the reliability of a capacitive touchscreen?

I'm working with a manufacturer who wants to use a touchscreen (like a mobile phone) to activate the machinery but is afraid the touchscreen could give a false reading. This would be a touch-and-hold ...
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2answers
107 views

Capacitance of semi-cylindrical plates?

For a visual reference of what I mean by semi-cylindrical plates check the diagram below. EDIT: The above diagram is not what I intend to implement. It is just to show anyone trying to answer the ...
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0answers
29 views

Sense capacitive change then apply high voltage

When an insect touches two of my wires the capacitance between them changes. This can be detected. Now after a change is detected i want to put high voltage on those two lines. I am afraid however ...
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0answers
28 views

How to read out a capacitive sensor, (CDC, CVC, TDC)?

What are the main principles for reading out a capacitive sensor? I read a lot, but I cant figure out what re the different options. I think that an option is to convert the capacitance into a ...
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0answers
15 views

How to use cy8ckit-041-41xx as a mutual capacitance sensor?

I want to use the cy8ckit-041-41xx as a mutual capacitance sensor. However, I am confused on how to proceed as I was unable to find any documentation or tutorials on how to use it as a mutual ...
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5answers
2k views

Coax cable - capacitive load

I still have an understanding problem with impedance matched coaxial cable and its behaviour. We do impedance matching to prevent reflections. How does my signal source see the whole cable? At a ...
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2answers
95 views

Transfer function of a second order capacitive accelerometer

In order to find the transfer function of the accelerometer MMA7361L based on the information given in the data sheet 1 I first made a hypothesis that it a second order sensor since it has a ...
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0answers
14 views

how can I simulate the MMA7361L?

I wanted to know if there is a simulator that could include the model of the capcitive accelerometer NXP MMA7361L, and if there is a tool-box in matlab that could include it or should I find the ...
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0answers
28 views

Is there a material that I could use to generate cap touch presses? [duplicate]

I want to automate some testing that uses captouch as the interface for the human user. I would love to use an Arduino or similar's GPIO to create the equivalent press and release events from a finger....
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0answers
70 views

Bypassing Capacitive Touch Sensor on Wemo Insight

I have a WeMo Insight plug that I'd like to use to monitor the power consumption of my networking devices but unfortunately if the power goes out, the WeMo device will not come back on automatically. ...
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0answers
81 views

Where is the capacitive coupling in this adafruit soil moisture sensor?

Here is the moisture sensor: https://learn.adafruit.com/adafruit-stemma-soil-sensor-i2c-capacitive-moisture-sensor/downloads It has a large copper area insulated with soldermask that sticks in the ...
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1answer
391 views

Diy capacitive level measures sensor [closed]

I am trying to build an capacitive level measures sensor. I am new to this and if anyone can guide me in the right direction for a breakout card and so on. Requires: The size of measure level are ...
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2answers
67 views

How is the (dis)charging process of capacitors in series calculated?

How is the (dis)charging process of capacitors in series calculated? I know that $$C_{total}=\frac1{\frac{1}{C_1}+\frac{1}{C_2}+\frac{1}{C_3}+...}$$ $$Q_{total}=Q_{1}=Q_{2}=Q_{3}=...$$ $$V_{1/2/3}=\...
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1answer
53 views

Suggestion on Power supply design

I am looking for Transformerless power supply design. I have MCU 5V. and would like to drive 12V/24V relay with single LED. i have 4 pots 10K/200k for timing So i prefer 230VAC to 12V/24Vdc output ...
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1answer
60 views

Predicting and Evaluating Connector Performance in a Capacitive Sensing Application

I have built a capacitance measuring system using the Texas Instruments FDC2214EVM evaluation module. The system is used to monitor the location of the user's hand in an enclosed space, where ...
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1answer
220 views

How can I override a capacitive touch on-off switch? [closed]

I bought a floor lamp for use with a mechanical timer that turns electricity on and off using a set schedule (for example, when you're away but want to convince others that you're still at home). ...
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0answers
98 views

Ground mesh under the capacitive touch pad

I am going replicate a circuit basing from adafruit AT42QT10xx, I will be using the AT42QT1010 variant. The touch pad is the blue pad bottom layer, but there is this mesh on the top layer after i ...
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1answer
152 views

how to make a variable light dimmer circuit without potentiometer?

I was looking at the Wemo Dimmer and thought to make one at home myself because the price of it is very much if I buy(including import duty). I searched for the knowledge which helps me create a ...
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3answers
168 views

Stability - Driving a Capacitive Load

I know I have been asked not to provide video links and ask questions. But I have no proper guide/mentor or anyone who can provide me better answers other than users in this site. So, please pardon ...
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0answers
46 views

Capacitive Power Supply Torch

I'm an amateur at electronics circuitry and concepts. I have designed a simple capacitive power supply using few web images and brief lessons. I understand that this type of transformerless power ...
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1answer
71 views

Qtouch with non-Atmel microcontrollers

Simple question really. Can I use Atmels Qtouch library with non-Atmel MCUs (such as an STM32)? It seems like Atmel has a solid line of capacitive touch ICs, ...
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137 views

Driving Capacitive Load

I did a bistable multivibrator drive NPN mosfet using timer55 and my mosfet drive power LED. Our Load has 3 circuit stage which are emc filter + smps circuit + power Led. I have a problem at that time ...
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61 views

How to prevent capacitive discharge on my load after MOSFET off state

I built a button on off latch circuit using nand Gates then connected latched output to Nmosfet's gate with a resistor. My load is a smps circuit drives the power Led and this circuit has emc filter ...

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