# Questions tagged [capacitance]

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

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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 ...
79 views

### 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 ...
68 views

### 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 ...
102 views

### 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 a ...
2k 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 ...
72 views

### 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 = ...
161 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 ...
237 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 ...
812 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 ...
14 views

### 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 ...
106 views

### 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 isolate the DC 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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### 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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### 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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### 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)...
504 views

### 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 ...
654 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 ...
453 views

### 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.
375 views

### 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 ...
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### Im struggling with identifying the capacitance on this cap

Cant find capacitance for this capacitor marked x1 100v UD any help appreciated can find capacitance for this capacitor
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### Sampling DC and AC components of capacitive sensor

I'm using a MEMS capacitive pressure sensor SCB10H. As I understand it, I can wire it up in one of two ways. Either I can measure the absolute capacitance using a chip like the TI FDC1004. In this ...
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### how can i attenuate mobile signal completely(maybe 90%) and please suggest me the wall thickness ,as i want to use copper or aluminium [closed]

please help me as i want to make a den for my dog that completely attenuates em waves of phone
2k views

### Measuring MOSFET input capacitance?

Am I calculating total input capacitance or gate capacitance or none of the above? And are my calculations even correct to begin with. The point of this is that I want to know what gate capacitance im ...
700 views

### Finding a CPU's Capacitive Load - Computer Architecture

I'm new to computer architecture, and found a question similar to that on this site already with actually quoting the same text book. I'm struggling to figure out if the answer is 1.77Ghz or 3.55Ghz. ...
168 views

### Measuring 0805 Capacitor values under 1nF

Other than investing in an expensive tweezer type meter for SMD components, what would be a good method for the layman to find the capacitance of an 0805 ceramic capacitor whose value is below 1nF? My ...
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### What are the considerations for designing a capacitor bank?

I am trying to understand capacitor banks and capacitor discharge, and how to work out what I need to generate a short pulsed current. If I would like to use capacitor discharge to produce a sudden ...
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### variation of thickness of dielectric layer for different textile-based capacitive pressure sensors

For my thesis I am working with textile-based capacitive pressure sensors and I am struggling to see how much variation in thickness of the dielectric layer you can have before you have noticeable ...
105 views

### High AC voltage on Touch Sensitive Switch

I recently got a 120V/240V On/Off Touch Switch kit (ZIJIA P12-L56). They are a cheap way of adding Touch Lamp functionality to a standard lamp. It works great and I immediately started poking ...
125 views

### Time taken to charge a capacitor

I was told by a lecturer to study the 555 timer in astable mode, I'm pretty confident I know just about everything now except for how the formula for the output high and low time was derived. Things I ...
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### How to calculate capacity of a battery from the readings of current and time?

The requirement is to compute the capacity of the battery in order to calculate the capacity degradation. The input which can be acquired are current, voltage, relative time, battery level (in terms ...
2k views

### Shortening a long antenna with a capacitance

In many circumstances it is not possible to make a dipole antenna that has the optimum length of $\lambda/2$ (or monopole with ground plane of length $\lambda/4$). Car antennas are for example ...
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### How can I make a model of a single wire CAN bus cable?

I'm currently working on a project of analyzing the latency of a CAN bus network with transceivers and without transceivers. The latency parameter here will be analyzed with the effect of bus line ...
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### input filtering capacitor design [closed]

How to make input filtering capacitance circuit (capacitor bank) if values of one capacitor are not enough to handle with voltage and capacitance? For example, calculated input capacitor value for AC-...
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### Measuring an electrical signal without tapping wires

I came across a product which taps into a twisted pair differential signal without making physical contact with the conductors. Instead, the wires are untwisted for a few centimeters and clamped into ...
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### Capacitance decay of SMD ceramic capacitors

I want to use a 330nF X7R ceramic capacitor for an analog circuit. Obviously the capacitance value is very important for the correct working of the circuit. I haven't found on the datasheet if these ...
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### Confusing phasor representation

Why capacitive impedance has the magnitude $Z_{c} = \frac{-j}{\omega C}$ but in the phasor diagram, we represent it as a vector pointing in the upward direction?. Same is with the case of an ...
264 views

### Does voltage rating increase on ceramic capacitors have any effect on the performance of the capacitor? [duplicate]

If I have a circuit that is designed for a ceramic, SMD, 0402, 1uF, 10%, 10V rated capacitor, and I swap in a ceramic, SMD, 0402, 1uF, 10%, 25V capacitor would anything change in the circuit? Would ...
160 views

### Needed capacitance calculation

I have a circuit in which I have a Li-Ion 3.6V battery, then a voltage regulator that outputs 3.3V and then the circuit. Also it contains a couple of tiny 1uF decoupling capacitors in front of and in ...
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### Do not understand why current flows in undamped oscillator circuit, and getting troubles in practice

I want to make my own antenna, so I started to make a generator. I found scheme below (only without a K key in the bottom) in internet, and it seems to be exactly what I was looking for. There PNP ...
321 views

### Measure input capacitance of I/O pin

I'm looking for a simple laboratory procedure (and required equipment) to measure the input capacitance of each IC I/O pin. Thanks in advance.
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### How do we measure capacitance by change in vibration

A capacitively based MEMS affinity glucose sensor. link to the IEEE paper, from where I've got this doubt. The gold electrodes are separated with some distance and the permalloy is vibrating with ...
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### Can I change a capacitor with one with a higher capacitance?

Hi I have just joined after lurking a lot because I haven't found an answer that was specific enough for me. I have a Soviet synthesizer (TOM 1501) and it has some odd defects such as clicking noises ...
594 views

### Non-coaxial 50 ohm cable for LVDS

I'm looking to configure a Xilinx Zynq-7000 custom board with LVDS receivers according to the following diagram. In my setup, the 'IOB' on the left represents an LVDS driver from a radar receiver and ...
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### Driving a difficult load with an Op-Amp: high capacitance, high current, high speed

I've been banging my head against this problem all day. I have a bizarre load that I need to drive over 88 feet of SMA that is a 68 ohm pullup to 15V. The cabling adds 2.64 nF of capacitance. I've ...
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### Discharging a capacitor quicker, using an exterior time varying magnetic field?

I was analyzing the possibility of varying an exterior magnetic field, that's aligned in direction with the magnetic field produced by the displacement currents(both parallel in the same plane) shown ...
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### Complex Capacity

Recently we have been tasked to calculate the complex permittivity of a given capacitor. The formula suggests using the complex capacity of the capacitor. Which is what is getting me confused. I ...