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Questions tagged [capacitance]

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

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Failed to plot junction capacitance versus reverse voltage in LTspice

The 1N4001 diode's junction capacitance versus reverse voltage plot is given as follows: I guess to measure this capacitance they applied 1MHz 50mV pk-pk sine wave signal as reverse biased and varied ...
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Capacitor value denoting

Hello I'm trying to understand the value in microfarads of capacitor labelled, C791 103(2) And how to calculate if the SI unit is not given thanks.. diagram below One more question if you don't mind ...
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25 views

Capacitance to useful signal conversion

Working on a project, where we need to measure the change in capacitance(capacitance change roughly from 0.5 pF at the start, to 20 pF at the end of the measurement). On the variable cap, only the ...
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How to findout the value of V(s)/V(e)?

How to findout the value of V(s)/V(e)? Is it correct? $$\dfrac{Vs}{Ve} = \dfrac{\dfrac{R2 \cdot \dfrac{1}{j\omega C}}{R2 + \dfrac{1}{j\omega C}}}{R1 + \dfrac{R2 \cdot \dfrac{1}{j\omega C}}{R2 + \...
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50 views

Eigenfrequency of a toroidal resonator

All units are in the SI I'm doing my task from vacuum electronics - for the given klystron with a toroidal resonator[ Resonator: I have to find the $h$ parameter, that will satisfy given ...
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21 views

Hover Stylus for capacitive touchscreen [duplicate]

Capacitive touchscreens are designed to react to the capacitance of a human body. To my understanding the touchscreen is measuring local distortions of the electric field. Is there a way to influence ...
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53 views

what does Loss Tangent means in capacitor?

As we know the definition of Loss Tangent in capacitor which it is: When a sinusoidal alternating voltage is applied to an ideal capacitor, the current advances by pi/2 in phase. In the case of a ...
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How capacitance of human skin varies with frequency?

I want to know the variation of the capacitance of human skin as frequency is increased. Also how it affects the impedance of the skin?
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Moving a capacitor in a time varying or non-time varying magnetic field?

1) If a simple parallel plate capacitor connected to a circuit, and discharging, were to move in an exterior magnetic field, what would happen to the interior region? Interior region components: ...
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52 views

Soil Moisture Sensor Design

I am working on the development of a low-cost capacitive soil moisture sensor which uses dielectric permittivity changes to estimate moisture. I want to use FDC2214 for Cap to Digital Conversation. ...
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1answer
29 views

Questions about capacitive sensing

I'm trying to use the FDC1004 capacitance-to-digital and I have a few questions: Why do we (our fingers or another part of our body) act as the other conductive plate - don't we have a very large ...
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1answer
73 views

Powering phone using LDO regulator on battery terminals - what reservoir cap to use?

I have rigged up an old phone that does not run without a battery by attaching an AMS1117 regulator to the battery terminals. The regular is fed from +5V USB, and outputs 3.3V. The regulator comes on ...
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Using only stray capacitance for MCU oscillator circuits

I've included a diagram of typical Pierce oscillator circuit taken from ST Application Note AN2867: The note suggests that C_L1 and C_L2 should be chosen such that the following equation holds: ...
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81 views

Can I add output capacitance to a dc/dc boost converter to help with current spikes?

I have been playing around with achieving better power in my 30-year old RV. I want to create both AC and DC systems to provide power. This has essentially 3 routes from my battery to device: Samlex ...
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1answer
57 views

Why is the upper part of a Leyden jar terminated with a small sphere?

I often see pictures of Leyden jars that have a small ball attached to the end of the upper connector, was it just a question of aesthetic ?
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How does placing cap between signal GND and earth GND solve common mode noise?

Thanks in advance for your time. I am reading several articles about differential mode noise and common mode noise. Among which I found the below 2 pretty instructive: https://www.murata.com/~/media/...
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Estimate capacitor parameters

I am thinking of making a capacitor, just for fun/for studying purposes. And I thought of the following exercise. In my local store, there exists rolls of polyethylene food film and aluminium foil. ...
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ring-capacitor design

I created a simple design, based on the fundamentals of a parallel plate capacitor. Making a co-axial/tubular design: Front view: The "Air gap" is there to allow current flow in one-direction, from ...
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How to remove 50 Hz, 100mV noise? [closed]

I am getting 100 mV noise signal at 50 Hz. I do not know the origin of the noise. What should I need to do to remove it?
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RC-Circuit With Two Capacitors that are neither in parallel nor in series

Background In our course, we have covered everything related to RC-RL-RLC circuit, however, all questions were based on the fact that you either have parallel or series connection. I've not taken ...
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51 views

Converting “MPR121 capacitive keyboard” sensor filter data into capacitance values?

The project that I'm working on, the MPR121 capacitive touch sensing keyboard connected with a 8051 microcontroller, my first intention when I started implementing the project was to measure the ...
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Focusing on Frequencies with Guitar Pedal Capacitors

I just built my first guitar pedal (a Bazz Fuss fuzz pedal), and now I'm messing around with the electronics a little bit. I was just wondering how I could target specific frequencies with the pedal. ...
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Imaginary Capacitance and Imaginary Inductance interpretation and relations with circuit theory

Today I came across with Complex Capacitances and Inductances for the first time: $$L(j\omega)=L_{real}+jL_{imaginary}$$ $$C(j\omega)=C_{real}+jC_{imaginary}$$ So I started looking at their meaning ...
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Mitigate parasitic capacitance coupling

First conceptually: Assume you placed two metal electrodes/tags on a fencer's body: one on the torso (large, the lamé), one in the hand (small, the guard). Equipped with a Capacitive Sensor located ...
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56 views

Point of contact with a capacitor plate & rolled design?

With a simple parallel plate design for a capacitor, does point of contact(to the external circuit) matter? I imagine any point(a - e) would yield the same feature in storing/discharging charge. ...
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Measuring a small distance via capacitance

I am interested in measuring a small \$d\$ between two objects shown below by measuring the capacitance between the Terminals denoted as T0 and T1: The distance \$d\$ is roughly 1mm +/- 0.5mm ...
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Capacitor electron flow

Well I was just wondering, a capacitor is made of 2 metallic plates separated by insulating material. During the charging of the capacitor electrons flow towards the opposite direction the battery's ...
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Calculate the turn-off delay of an LED in parallel with a capacitor

I am trying to create a Custom turn off delay for an LED. For this I take an Capacitor in parallel to an LED My Idea so far was: I have the General Equation for an Capacitor. And the General ...
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Why wierd capacitance values [duplicate]

Why are capacitors available with values like 378 µfarad and 0.22 farad which have prime numbers like 11 and 7 in factorization instead of values like 375 µfarad and 0.2 and 0.25 farad ...
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High voltage dielectric breakdown & layering insulators

I’m going to use 230 kV as the reference voltage for the example below; I know if I put a piece of metal too close to a 230 kV source it will breakdown the air and jump to the piece of metal causing ...
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1answer
145 views

3 phase motor running on single phase using steinmetz delta connection

How do 3 phase motors manage to run on single phase power using the Steinmetz delta connection with a single capacitor? I thought capacitors only shift the phase angle upto 90 degrees, whereas 120 ...
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Finding equivalent capacitance and resistance from DC circuit with combinations of R and C

In order to get the simplest RC circuit and get equivalent circuit tau: How can be its transient studied if before t = 0 there only exists one resistive part of circuit? I's obvious that before t = ...
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Drain capacitance of CMOS inverter

How to find the total drain( NMOS+PMOS) capacitance of CMOS inverter in cadence virtuoso?
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73 views

Selecting true crystal settings for 328P [7.3728 MHz]

I want to make a new board working with 115200 (gsm modem) UART. so I want minimum baud error rate. I look at https://cache.amobbs.com/bbs_upload782111/files_22/ourdev_508497.html table and decide ...
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How are individual mutual capacitance signal read out from a touch screen?

If I understand this correctly, on a touch screen, you have a a grid based system where the rows and columns are either driving or receiving. When you touch the screen a mutual capacitance arises ...
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40 views

Junction Capacitance Sensor

I would like to know if it is possible to measure or calculate junction capacitance of sensor (current source similar to photodiode) and if it is how. The sensor manufacturer does not have any ...
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58 views

Capacitance of circular parallel plate capacitors

I've been trying to solve this question for a while now , but I can't seem to get to the written solution. Question : Calculate the capacitance of a parallel capacitor having two identical conductor ...
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What is the difference (in operation and performance) between a single-ended grounded CDC and a single-ended floating CDC?

For an undergrad project, I designed a capacitive pressure sensor that measures capacitance across two parallel plates and calculates a proportional amount of pressure (i.e. increased pressure = ...
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76 views

capacitance measurement circuit

For sensing capacitance value of sensors below circuit has common usage in literature. I want to continue talking about simulated circuit in bottom. Could be possible writing an equation similar to ...
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Measure Junction capacitence of sensor

I would like to know how can I measure or calculate the junction capacitance of an oxygen sensor(or photodiode or any current source sensor). The manufacturer does not have this information on their ...
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Voltage in RC circuit with unknown frequency

We were given the task of finding the voltage drop across R1 of the circuit below with the following alternatives: 5.8V 4.8V 4.0V 10.0V All given information is contained within the image, i.e. no ...
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Capacitors in Amplifiers

I am reading about single stage CE Amplifiers and I don't understand how the capacitors work here. 1) Coupling Capacitors: "The coupling capacitor is used to isolates the d.c. of one stage from the ...
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Calculating Required Bulk Capacitance

All, Lately I've been thinking more about bulk capacitance in my designs. Previously, I've been careful about part selection and placement for decoupling and filter capacitors during design. Once a ...
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65 views

How can I make a capacitive touch panel that can sense position?

I'm trying to make a fairly large touch panel (no display). Or if that's any easier: a set of touch ribbons. The Wikipedia page on capacitive sensing and other online resources seem to pretty much ...
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1answer
39 views

Real world objects touching reading the same capacitance?

In my project, I am developing a capacitive sensor based system which attempts to identify if two real world objects(*) get in contact with each other. I have done my homework (some) on Capacitive ...
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1answer
55 views

Trouble testing capacitor

I have a Radio Shack DMM (Cat #2200811). I'm trying to test a 100uf 16v electrolytic capacitor on the auto range capacitance setting. I tried it with a 30uf 160v cap. and it worked (measured as 29uf)...
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What would be the combined dielectric constant of two dielectrics in series?

Let's say we have two parallel conductor plates. In the middle, there is not one but two layers of dielectrics made of different materials. If we know the relative permittivity of each dielectric, how ...
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104 views

Does the capacitance values matter in a full wave voltage doubler?

I've simulated the following schematic on Cadence, and another less professional simulator called 'everycircuit'. I initially had a C1 = C2 = 10uF which simulated correctly on both simulators. Then I ...
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how do i know if Vc(0+) or Vc(0-) is zero?

i mean like in this picture, why is Vc(0-) = 10 v? why isnt it =0? when do i decide that there exists a voltage there even though it was in steady state? im not completely getting it.
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Three phase motor driver DC link, DC bus capacitor values

I am designing a motor driver for a three phase brushless motor and have been looking for a capacitor value for the DC bus of this circuit (C1). Most of what I have found when researching deals with ...