Capacitance is the ability of a body to store an electrical charge

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Capacitive touch detection on large metal object

I'm trying to get capacitive touch to work (on batteries). I want to detect touch to a large metal object, namely a metal door which is connected to the sense pin. The fact that it is a large metal ...
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3answers
317 views

How can I measure gate capacitance?

Is there an effective way to directly measure the gate capacitance of a power MOSFET, like say the IRF530N? The way my circuit is behaving would indicate that the effective gate capacitance is ...
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416 views

Voltage dropping capacitor doesn't work?

I connected a voltage dropping capacitor in series with 220v AC supply and I measured the output voltage and it was 220 v too. I was expecting to get a voltage that is less than 220 volts. Did I make ...
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1answer
29 views

How to estimate a value for IC capacitance in a I2C bus?

What is a reasonable value to use as the capacitance a I2C device adds to a bus if so is not stated in the datasheet? With this value I intend on calculating the pull-up resistors to eventually use ...
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2answers
78 views

Is my Precise Capacitor Ratio Repeatable?

I have designed a 1Mohm, 0Hz-100MHz fixed attenuator circuit (15pf/300pf). I am using 1%, C0G capacitors. There is also a TS5A2053 analog switch connected to the output of the attenuator. The switch ...
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1answer
78 views

Is it possible to determine capacity and voltage rating of an unknown electrolytic capacitor?

Today I found a big electrolytic capacitor in a scrap yard. It is about 9 cm in diameter and 16 cm high. The only thing that is marked on it is polarity but nothing else. How can I measure its ...
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1answer
53 views

Can you ground the dielectric of a capacitor?

To measure the soil moisture of a house plant, I've put two knives in the soil (covered with shrink sleeve), and attached a capacitance meter. The dielectric constant of water is really high, and as a ...
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38 views

How to measure the capacitance of a capacitor? if labeled, what are the instructions to interpret it's tag… and instructions for the unlabeled

How to measure the capacitance of a capacitor? I believe this question will be answered with categorization. ex. by looking at the label (104, etc), by solving its value through calculation... the ...
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2answers
106 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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3answers
67 views

Capacitor rated for 100vdc on 5vdc board

As the title says, I have capacitors rated 100VDC 18pF. Can I use these on a board that uses 5V Max ? I can't really find any direct answer to that question. What I want to do is to put a crystal to ...
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19 views

On chip Interconnect : Coupling capacitance between bus lines

SoC interconnect lines have two sets of capacitance associated with them. The first being ground capacitance Cg(Capacitance between the interconnect line and ground plane) while the other being the ...
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37 views

How to prevent or slow down the discharging rate of capacitor once it has detected the peak values?

I have load cell-sensor that has a sensitivity of 2mV/V. I am using an instrumentation amplifier to amplify the sensor output depending on the load or force applied on the sensor. Followed by the ...
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1answer
49 views

Where can I find a good theoretical treatment of conductor shielding?

Suppose one has three current carrying cylinders lying on the same plane. Some of the electric field of the first conductor ends up on the second conductor, which creates capacitance \$C_{12}\$. But ...
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3answers
87 views

Why is the capacitor considered lossless, even if it can store/give out energy?

They say capacitor is lossless because average power is 0.But contradicting this is the fact that the energy stored/disipated by a capacitor is (1/2)CV^2.How and why is this?
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3answers
104 views

SPICE model for one terminal spherical capacitor

I have a circuit where at least some of the capacitance is coming from large, non-radiating, spherical conductors. I would like to model it in SPICE to better understand its operation-- is such a ...
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1answer
84 views

How would I measure an Ultracapacitor's Specific Capacitance using a PGSTAT128N?

I am building a capacitor using nanomaterial grown on a substrate. We are trying to figure out what our test fixture configuration should be when doing Cyclic Voltammetry on the cell. Our group would ...
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2answers
82 views

Resistors and capacitors calculation for 555 timer circuit

I am new to electronics and I want to try an experiment. I want to use a 555 timer to create an automatic food dispenser for my aquarium (something like opening a small door when the timer has ...
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2answers
69 views

How to calculte mosfet capacitors (Cgs Cds Cdg) knowing the charges Q

i need to use the best model fo the MOSFET in my circuit i'm simulation on PSIM, the MOSFET is Si4108-TI-GE3. But i am not given the parasitic capacitance values (Cgs Cds Cdg), i am only given this : ...
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1answer
63 views

At what capacitance and voltage are capacitors harmful? [closed]

I'm currently building a taser from scratch and would like to know which capacitor to use.
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77 views

Series LCR experiment

i am doing a series LCR experiment for measuring the resonant frequency taking, R= 100 ohm; L= 40mH; C=0.1uF. I am using a 10KHz audio oscillator having 10V p-p as the input. I have fixed the input ...
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0answers
79 views

Measuring Capacitance using AVR

I am trying to make a capacitance meter with AVR Atmega16. I use of analog comparator inside micro. Means when negative pin(AIN1) of comparator reach to postive pin(AIN0) micro going to interrupt ...
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2answers
61 views

Capacitance of a single charged plate?

Lets say we have a single plate that has a charge of +Q on it. A plate with charge -Q is infinite distance away. Will the plate with +Q have a capacitance associated with it? Why or why not? I was ...
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282 views

Why are high values of capacitance in low pass active filters not recommended?

I am designing low pass active filter (Sallen-Key structure) and I have come to a point where I have to decide what should be the value of C (C1 = C2 = C) and then calculate values of resistances. I ...
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1answer
109 views

Fundamental questions about capacitors? [closed]

I have read several chapters in several textbooks, watched several in-depth tutorials, etc. There are still somethings that were either not explained clearly enough for me, or not explained at all. ...
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1answer
47 views

If you put a MOSFET in backwards does the impedance change?

if I stick a MOSFET that should be going (S-D) to positive in backwards, and make it (D-S) to positive, all the current drops across the diode instead. This diode then approaches an impedance of 0. ...
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43 views

Power factor correction of predominantly inductive load component with capacitor

I started preparing for the college next year, and I came across this question: How can I express the capacitance of a capacitor which needs to be connected parallel to a predominantly inductive load ...
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2answers
42 views

How do I prevent a capacitive touch from registering?

I'm looking for a thin cloth-like material or something that I can treat materials with that will prevent a capacitive touch from occurring. Everything I've tried either is too thick, or still ...
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21 views

Rise time degradation by connecting to an input buffer

Suppose I have an imaginary 1.8V lvcmos output buffer and I know from the datasheet that it has an unloaded 10-90 rise time of 1ns. Now I'm going to hook up 6" of trace, to an input buffer who has an ...
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1answer
110 views

LC tank circuit feeding on op-amp, no oscillation?

Based on what I learned during this experiment I've built the following circuit using an op-amp configured as a buffer... simulate this circuit – Schematic created using CircuitLab The ...
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1answer
28 views

How to simulate parasitic reactances in a circuit

Does parasitic capacitance of a microstrip trace add to the value of a physical capacitor on the same trace? If one sees it as a series element, then it would seriously reduce the value of all ...
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0answers
28 views

Finding the input capacitance of this critical path

Hi so I'm trying to find the input capacitance of this critical path and then find the EF, Electrical Fanout, Cout/ Cin. Cout is given to be 10pF Okay here's my attempt at solving this. We know ...
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3answers
209 views

How to properly connect and drive varicap diodes?

can someone explain me how to connect and use varicap diodes? Please consider that I am a novice, so would be ok to use a clear and an exhaustive language/terms. Thank you. I often see these ...
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1answer
122 views

Measure I2C bus capacitance

We are trying to calculate how many I2C slaves we can hook up the I2C bus. We tried to run a square wave through a serial resistor and measure the rise time but we get a strange result. More nodes ...
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1answer
58 views

Related to varactor Diode?

I'm working on my project during this i face some problems... Here i mention my problem:- I required some variable capacitance whose range is C=0.05pF to C=0.5pF. So there is any variable ...
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2answers
34 views

reading capacitance on digital meter

So I bought this digital meter from radioshack because it tests capacitance. I have several caps on a TV power board, most of which are 47uf and 470uf with various voltages. when I check with the ...
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2answers
131 views

Understanding capacitive load conditions for a microcontroller

This is from a PIC24E microcontroller datasheet. My question is understand what does "load conditions for device timing" mean ? Does it mean in order to maintain timing (say for a high speed PWM ...
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1answer
60 views

Can two capacitors be used in series to get a equivalent capacitance in a circuit?

I am building a FM radio circuit and a 27pF capacitor(Ceramic) is required in that, but i don't have one. But i do have 56pF capacitors. So i was thinking that can i use two 56pF in series to get a ...
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1answer
43 views

Stray Capacitance in my load waveform?

I have just taken this trace of my Loadwave form for PWM controlled halogen dimmer. I was wondering if anyone could identify the cause of the transients below or above zero volts for each polarity. ...
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1answer
99 views

Trouble calculating time to drain a capacitor

Introduction I'm having trouble producing an equation that involving my MAX756 boost chip, a load and my 1.5F capacitor. Basically I'm trying to find out how long it would take for a 1.5F capacitor ...
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206 views

Simple ADC alternative by using a capacitor and digital Arduino pin

I'd like to measure a dozen potentiometers with an Arduino UNO. Unfortunately, the UNO only has 6 analog pins, but it does have about a dozen digital pins. Could I effectively measure an analog value ...
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1answer
125 views

How do I deal with different XTAL pin capacitance when selecting XTAL and load capacitors

I'm trying to select a 32kHz crystal and appropriate load capacitors for Atmega48A MCU. Atmega48A specifies different capacitances for Xtal1 and Xtal2 pins: 18pF for Xtal1 8pF for Xtal2 The ...
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1answer
95 views

What is power dissipation capacitance?

This question is derived from the answer to another question What is the input current of the 74HC595 The answer makes a note to the OP, that he should also consider power dissipation capacitance. ...
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0answers
49 views

How to switch on or off capacitance on a piece of conducting material?

I don't know if this is the right way of describing it, but I need to activate an area of capacitance on a touchscreen by applying some current to a piece of conducting material like tinfoil. I am ...
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2answers
112 views

Understanding to isolating sensor input capacitance

The circuit given above is pH sensor buffer circuit, picture taken from here. This circuit have pH sensor input and gives an output that can be read by multimeter which is U2's OUT_ pin . U1 is here ...
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2answers
226 views

How to calculate a electrolytic capacitor based on current and voltage to have the smallest ripple

I have built a circuit involving LEDs powered on 230V AC. The LED current driver that is powered on 30V and contains 10 LEDs of 1W each. 10 of these modules are linked in series and are ...
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1answer
45 views

Temperature Coefficient of Capacitance

How can I find the Temperature Coefficient of Capacitance of the following capacitor series: http://www.cde.com/resources/catalogs/TAS.pdf
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1answer
184 views

factors influencing capacitance of a cable

I am out of my depth here so I am looking for a simple explanation. If you have twisted pair cables of differing makeup, varying in conductive material, diameter of the conductor, number of twists per ...
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1answer
100 views

An “operation” game sensor where the stylus is NOT attached to the power source

Edit: The person operating the catheter will be wearing latex gloves. The only human tissue the catheter would touch would be that of the patient. Also, to clear up some confusion about what exactly ...
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3answers
92 views

help with capacitors and project

Capacitors have me crazy. I cant comprehend them even after lots of research. I know that capacitors deal with resistance, voltage, current and capacitance.(ohms, volts, amps and farad) but I cant ...
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51 views

Calculating capacitance at resonance

Could someone help me please asap, New to this ! Thank you! working out for the first one , could someone confirm? first question has been confirmed thanks Second question confirmation? thanks