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

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Resistivity and resistance. Permittivity and?

We know that resistance is dependent on both the materials resistivity and the geometry of the material. For a cylindrical or rectangular material the resistance is: $$R=\rho*\frac{l}{A}$$ where l ...
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0answers
96 views

Capacitance of two wires with a grounded wire between

I have measured the capacitance between wires number, say, 1 and 3. With the wiree #2 just floating, the result was 390 pF. But after i have grounded the wiree #2, the capacitance was 220 pF. What is ...
4
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2answers
248 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
43 views

load switch capacitance constraint

Considering using a Load Switch like DigiKey FDC6330LDKR-ND for powering on and off a device at the far end of a cable. The voltage and current requirements are well within spec however load ...
0
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1answer
67 views

How do I calculate the capacitor value (Farad & Voltage) given the pulse current, pulse duration & maximum tolerable voltage drop?

I have an electronic component with following characteristics: Operating voltage: 4.5V Peak operating current: 2000mA for 600uS every 4000uS. The device can ...
0
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1answer
33 views

Measuring self-capacitance of coils

Is there a simple way of measuring the self-capacitance of a coil? There are many estimates out there for self-capacitance based on number of turns and wire specs, but I'm wondering if I can do an ...
0
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1answer
38 views

Is the Delay in Strain Data Due to Capacitance?

I have designed a sensor board which gives a strain o/p based on wheatstone bridge principle(change in stress is measured through change in resistance). But the starting value is not at zero level,it ...
0
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4answers
120 views

Circuit capacitance question

Given the following circuit, what ways there are to calculate its total capacitance? Thing is this is not a simple case, and I can't really decide which part is parallel and which is a series, ...
0
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1answer
59 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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1answer
105 views

DIODE as capacitor?

How does Diode act like a capacitor when voltage across diode is less than forward voltage spec. Basically when diode is turned off? What is its usual capacitance when diode (zener) is turned off.
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1answer
46 views

Approximation of ideal capacitors?

Capacitors are often approximated as infinite conducting plates. I find this approximation surprising since the capacitors I've seen in circuits are only a few centimetres big. For all the ...
2
votes
2answers
85 views

Capacitance to Analog Voltage

I've been looking at theremins recently. I've built a simple one using heterodyne oscillators, but I was wondering how to make a capacitance detector similar to the theremin's antennas. Basically, a ...
2
votes
3answers
116 views

How does a dielectric alter the electric field?

My textbook is trying to explain why adding in a dielectric between two conductors causes a change in the field inside. They provide the following image: I don't understand how the second image is ...
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3answers
432 views

Violation of conservation of energy?

Say I have a parallel plate capacitor that has a vacuum between the plates and has electric energy U. If I then add in a dielectric between the plates while the capacitor is charged, the electric ...
2
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4answers
306 views

Capacitors in series?

Capacitors in series have identical charges. We can explain how the capacitors end up with identical charge by following a chain reaction of events, in which the charging of each capacitor causes ...
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0answers
83 views

Understanding how bypass caps work, mathematically

Assume there is a band of noises that you you want to filter with center frequency Fn. Then The complex voltage representing noise at frequency F is V_(F, T) = V(F) e^(i W(F) T), where V(F) is the ...
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1answer
121 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 ...
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0answers
18 views

Influence of a Capacitance Matrix of a voltage measurment

I am having a problem in understanding how, in a multiconductor system, the Capacitance Matrix influences the measure of voltage between two electrodes. In the case that interest me we have 4 ...
3
votes
4answers
235 views

How to calculate equivalent capacitance to a battery?

I have a 1.25V 2Ah battery and I'm trying to calculate a equivalent capacitance with rated voltage of 2.7V for each of those batteries. This is what I did: Work of Battery = \$1.25V * 2A * 3600s = ...
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0answers
146 views

how to find the value of a capacitor/varactor in cadence virtuoso

I've been given a MOS varactor model and layout to use in a project, and I need to be able to plot the capacitance as the applied voltage is swept. I don't know how to do this in Cadence and ...
0
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0answers
61 views

Children's board book - embedded electronics for question and answer - capacitance sensor?

What are the components needed for a system to implement the following: A children's board book with multiple choice questions on each page a child will use an electronic stylus device (with ...
14
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3answers
1k views

Why need the capacitors be as close as possible to the device?

Just a simple question: what exactly stands behind the need for placing the capacitors as close as possible to the current consuming device's pins? Is that the inductance, resistance or maybe ...
0
votes
1answer
49 views

Multiplexing and electric capacitance

I'm working on a project, it's basically a hand-drawn paper keyboard based on capacitance. I was thinking I can multiplex the different lines with shift register (74HC595) and switch (4066), and as ...
10
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1answer
149 views

Why do capacitors across my FETs minimize ringing/distortion?

I'm designing a 24V to 350V DC-DC Converter based on a H-Bridge. The power requirement is 500W and the circuit operates at 20KHz. The design works fairly well and I've achieved about 90% efficiency at ...
17
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1answer
404 views

What effect does selecting the wrong load capacitance for a crystal have?

I've seen questions such as this one and this one that talk about selecting capacitors that, in series, match up as closely as possible to the load capacitance of the crystal. What effect does ...
0
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1answer
82 views

Initial Conditions and current for an RLC circuit

It is required to find \$i_L\$ and \$v_c\$. It is quite easy to find \$v_c\$ from \$i_L\$ using simple integration. So, for now finding \$i_L\$ will be the concern of the question. Prior to closing ...
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3answers
221 views

Measure capacitance in softwire using Tina/Multisim/other simulators

Is there a way to measure capacitance of a capacitive network as shown below in Tina-TI, Multisim, or other simulators? I tried searching but I couldn't find any way to measure capacitance directly as ...
3
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3answers
150 views

Does current lead voltage during discharge in capacitors?

I can see that how current leads voltage while capacitor is charging. Looking at any capacitor charging diagram will explain this: (e.g figures in http://en.wikipedia.org/wiki/RC_circuit) However, I ...
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2answers
251 views

I2C and SPI Bus Routing

When routing an I2C (SDA, SCL) bus or SPI (SCLK, MOSI, MISO) bus to multiple slaves is it preferred to wire the slaves in parallel or series? Below are two diagrams with distances labeled to help with ...
2
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2answers
132 views

PCB design: power tracks under the ground plane - is the capacitance going to be disturbing?

I'm designing a PCB that currently looks like this: I stumbled upon an idea of moving the main power section (especially including 3.3uH coil) and the GSM modem (the one with several drills) to ...
0
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1answer
60 views

Parasitic Capacitance of TVS Diodes

This may be a naive questions but is the parasitic capacitance of TVS Diodes a useful capacitance for decoupling a chip? Imagine I had an IC that asked for a 10pF decoupling capacitor and I used a TVS ...
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4answers
257 views

Converting variable capacitance value to variable DC voltage level

I need a simple method to convert a small variable capacitance value into considerable variable DC voltage. Capacitance value range = 0nF ~ 14nF DC value range needed = 0V ~ 6V What I've tried ...
3
votes
2answers
95 views

Telegrapher's equations

Something about the derivation of Telegrapher's equation is really bugging me. When deriving the Telgrapher's equations for a transmission line using a model as shown above, why do we only use a ...
0
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1answer
185 views

Can i calculate the parasitic capacitance in Altium?

As you know for calculate the capacitor of crystal(for MCU) you should use of this equation: CX = 2*(CL - Cstray) We can find the Cl in crystal's datasheet but, for Cstray, we should calculate: ...
3
votes
1answer
89 views

Capacitive sensor implemented on PCB - possible issues?

I want to implement a capacitive sensor in my design. I'm thinking of doing this by adding two large(-ish) copper areas on my PCB design and using those as the capacitive plates. I would then bond the ...
0
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1answer
83 views

Measure resistance and capacitance with bias in low frequencies

I have a device which can be modeled with a resistor in parallel with a capacitor. Now I want to measure its resistance and capacitance as a function of voltage bias (from -2V to 2V) and frequency ...
2
votes
1answer
125 views

Load capacitance estimation for compensation of switching power supplies

I'm calculating a compensation network for power supplies based on the LM20323MH from TI. I have slight doubts about correct estimation of output capacitance to use in the calculation. The board is ...
21
votes
4answers
1k views

How do transposition towers in transmission lines work?

There're such things as transposition towers in power distribution powerlines. The idea is that for example you have three conductors running in parallel at the same height and the leftmost of them is ...
2
votes
1answer
276 views

Finding a CPU's Capacitive Load

I am very very new to the electronic engineering side of things but I am taking a class on Computer Architecture. I have ran into a problem. Power = Capacitive Load * Voltage ^ 2 * Frequency ...
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votes
1answer
146 views

In a 50 Hz system a capacitor is connected to 11kv AC bus [closed]

there is 50 kvar being supplied to the load. Find the capacitance. In a recent Electrical exam I got this problem, but wasn't able to answer it. Can anybody give me a clue on how to solve it? ...
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2answers
73 views

Voltage output in ripple filter

we got this ripple filter circuit as shown in this figure.Input voltage $$ V=v(1+\cos (\omega t)) $$ is fed to left input and then find output voltage. Now this problem confuses me. For instance ...
2
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2answers
152 views

terminated cable capacitance

As much as I know, the input impedance of a coaxial cable with a characteristic impedance of 50 \$\Omega\$ which is terminated with a 50 \$\Omega\$ load resistor, should be 50 \$\Omega\$ as well. This ...
2
votes
2answers
205 views

Reducing capacitance of a wire

Given a wire and a piece of foil wired to a bread board, is it possible using capacitors wired in series (or some other method) to significantly reduce the capacitance of the wire/foil?
4
votes
1answer
232 views

Why do some electrolytic capacitors increase in capacitance with age?

All in the title really; I've been repairing music equipment for years and replace electrolytic capacitors quite often. Many times I've measured the capacitance of an old cap and it will read double ...
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1answer
73 views

When distance between the plates is increased, what will happen to the value of the capacitance

When distance between the plates is increased, what will happen to the value of the capacitance. (a) Increases (b) decreases
7
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3answers
234 views

Will this approach accurately measure capacitance and infer spacing?

I am interested in any feedback or caveats regarding the following capacitance measurement method before I begin setting it up. For an experiment, I have come across the need to measure and track the ...
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1answer
147 views

ESR and CSR of Capacitor

I'm trying to spec out an output capacitor for a TPS7201 voltage regulator (http://www.ti.com/lit/ds/symlink/tps7201.pdf). It needs to be selected carefully as it is used to stabilize the internal ...
0
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2answers
139 views

Current carrying conductor axially through a copper ring

What effect would a copper ring around a current carrying conductor have on the current in the conductor? How can I go about mathematically modelling the current in the conductor? Details : The ...
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1answer
169 views

Depletion region's length in diode

Assume that the \$C-V\$ curve of a Silicon diode is the following The equivlant \$\dfrac{1}{C^2}=f(V)\$ is shown next The slope will give me \$slope=\dfrac{2}{\epsilon q N_d}\Rightarrow ...
0
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1answer
133 views

Trouble Detecting pF capacitance with Arduino

Im working with an EAP (electroactive polymer) thats capacitance changes when deformed. It varies between the ranges of around 0.5 - 3 nF. Im trying to connect it to an arduino to take readings that I ...