Questions tagged [capacitive]

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1answer
57 views

Pre-charge resistor and contactor power dissipation calculation

I am building my e-motorcycle. I am planning to use only one contactor instead of using three contactors. In my plan, pre-charge resistor and contactor circuit will be main contactor too. I am curious ...
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0answers
27 views

Correct design of capsense controls

I am trying to design a PCB with some capacitive controls. My first iteration did not seem to work well: This was a 2-layer 1.6mm board with one circular control, and 5 buttons. The board is 48mm ...
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0answers
54 views

People detection in large rooms using antennas

After coming across a 2004 installation by Carsten Nicolai titled "anti" where he used a theremin as an element for presence sensing, I was wondering if this principle could be extended to ...
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0answers
26 views

Capacitive load in inverter

I'm trying to understand the effect of a capacitive load at the output of an inverter. And how does it affect the output signal when this capacitive load is high and when it is low? Could anybody ...
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1answer
103 views

How to detect which finger touched the mobile screen [closed]

I'm working on a project where I need to detect which finger touched the mobile screen i.e capacitive screen. I'm not talking about double finger touch or single or drag and move etc. I'm asking which ...
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1answer
86 views

Capacitive voltage divider question

I see a few discussions on this but cannot really find the "definitive" answer. I am building an audio amp and have two modules, one requires 18-0-18V AC and the other 12-0V AC, the 12V ...
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3answers
170 views

Bad capacitive touch screen sensitivity when running on battery, without earth

In short: I´m working on a battery driven handheld device with capacitive-touch screen. The capacitive-touch works perfect when the PCB connected via USB, but it loses sensitivity when driven by ...
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2answers
65 views

Adjustable voltage, 1 MHz capacitive biasing

I'm a budding physicist with little electronic design experience and am interested in driving an alternating E-field of adjustable strength within capacitive loads. Buying a several thousand dollar ...
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2answers
53 views

LED on lamp outlet flashes when switch is off - is this capacitive coupling charging the power supply? And what to do about it? [closed]

I wanted to connect an LED light chain to a lamp outlet in my house in order to turn it on and off using the wall light switch. I have dismantled the 230V to 3V power supply that was built into the ...
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0answers
46 views

Soft-start design and performant with short-circuit test

I am working on a soft-start for a capacitive load. I using module QSB40024S24 to create 24V output. At first, I allowed the output of the module to connect directly to a capacitor array (21.4mF in ...
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1answer
62 views

Calculate -3db point in low pass inverting transistor audio amplifier

What I am trying to do: I am looking to find the \$ -3dB \$ frequency for my common emitter transistor amplifier with a capacitor in the feedback loop. I have somewhat of an idea, but I wanted someone ...
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3answers
39 views

Capacitive load of connecting cable for a temperature sensor

An LM35 temperature sensor is 4m removed from the Arduino to connect it too. The available cable has 4 wires with a diameter of 0.6mm (0.28 mm2 area) as well as a, seemingly aluminum, shield . The ...
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0answers
38 views

Capacitive touch sensor senses every materials touch

I have a ttp223 capacitive touch sensor. It has three pins, VCC GND and I/O. I left I/O open for test purposes. I connected the VCC to 5V and GND to ground. When I touch the sensor, its led indicator ...
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0answers
43 views

Grove capacitive fingerprint sensor not working

I have just purchased one grove capacitive finger print sensor. link. I am using Arduino Nano and followed there tutorial but the example code isn’t working. Blue light on sensor never turn to green ...
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1answer
114 views

How to detect which pins on a pin display are touched using capacitive sensing

I'm working on a project to apply touch sensitivity to a modified pin display (30x30). The goal is to allow someone to interact with the display through their fingers and ideally touch. We initially ...
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1answer
56 views

Capacitor 250V DC

I have 0.22uF 250V DC MLCC SMD capacitor. Can I use it for 230V AC main as capacitive power supply? Your suggestion will be helpful for me.
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1answer
61 views

Different battery capacities in series is poor

How is the scientific (electrochemistry, physics, electrical, etc) explanation on different battery capacities in series is bad or poor and will damage them ?
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10answers
4k views

How can human finger pressure be measured?

I am dealing with a situation where a patient can only very lightly press his fingers / hand to signal what he / she wants. Speaking or eye tracking is not possible. The person is also not able to ...
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0answers
47 views

High-side mosfet switch placement

this is a power circuit I'm trying to complete: the button at top turns the curcuit on, supplying VCC to mcu, and the MCU will output a high signal to a pin (marked in pink) which turns the N-MOSFET ...
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1answer
64 views

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

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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2answers
69 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
97 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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0answers
70 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
114 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
103 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
45 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
89 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
42 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
459 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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0answers
43 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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0answers
29 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
26 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
450 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
48 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
96 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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0answers
190 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
328 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
60 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
105 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
5k 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
107 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
40 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
175 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
123 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
132 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
45 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
166 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
40 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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5answers
3k 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
169 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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