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Questions tagged [capacitance]

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

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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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31 views

DC-Link capacitors sizing for 3 phase inverter, which is feeding BLDC motor [on hold]

I would like to ask about an estimate for inverter DC link capacitors, where this inverter will supply 48V 20A 3phase Brushless DC motor and it's driven using a 5 kHz PWM.
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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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3answers
86 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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82 views

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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42 views

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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21 views

Direction of the electric field & displacement current within a rolled capacitor?

Considering that the direction of the E-field and the displacement current with a classical parallel plate capacitor are perpendicular to the plate's area; I'm not sure how they would be if the ...
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51 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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31 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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43 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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19 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 ...
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38 views

2N7000 Level Shifter: High Voltage Peak on Low Voltage Side

On the internet I saw, that a lot of people use the 2N7000 to realize a level shifter from 5V to 3V3 and vice versa. Firing up the simulator of my choice I saw, that there is a capacitance somewhere, ...
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54 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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38 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.
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46 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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1answer
75 views

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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26 views

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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60 views

What's the electrical explanation for a fluorescent light bulb's measured capacitance?

I tried using an LCR meter to see if I could measure a capacitance with a standard 10 watt fluorescent light bulb. I was expecting a capacitance in the picofarad range, but instead, I measured a ...
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290 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 ...
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152 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. ...
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2answers
85 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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1answer
72 views

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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0answers
55 views

Help to choose capacitor in CYT1000B LED driver circuit

I am planning to build LED driver circuit using CYT1000B (datasheet). The datasheet has this example circuit: (Do not look at bridge rectifier part, it is wrong!) Resistance Rs can be calculated as ...
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1answer
26 views

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 ...
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1answer
32 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 ...
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36 views

Is using an external capacitor in a slip ring induction motor viable for increasing it's starting torque?

I've been reading about slip ring induction motors lately and several sources, including Wikipedia and LearnEngineering (a YouTube channel), mention that adding an external resistance will increase ...
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25 views

Battery capacity for optimal life

I am planning to construct a small electromobile for which I will use a 3kW electric motor which will be powered by li-ion batteries. It would be sufficient for the vehicle to run for about 1 hour ...
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2answers
71 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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1answer
67 views

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 ...
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1answer
137 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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2answers
115 views

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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1answer
81 views

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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2answers
72 views

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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4answers
91 views

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 ...
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88 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 ...
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2answers
73 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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1answer
64 views

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 ...
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118 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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2answers
57 views

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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98 views

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 ...
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1answer
106 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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1answer
91 views

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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1answer
120 views

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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1answer
56 views

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 ...
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2answers
186 views

Why do I measure (almost) no voltage between 230V phase and my body?

The other day I was experimenting with a multimeter and checked the voltage in one of the electric plug at home. Without surprise I measured around 230V between phase and neutral and also 230V between ...
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1answer
68 views

Is this a reasonable way to get >50 capacitive touch sensors?

I'm looking to include 50-100 capacitive-touch sensors in a project. I've found these SPI 12-key capacitive touch sensors. Would it be reasonable to use several of these for such a project, or is ...
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2answers
72 views

Is this phenomenon capacitive coupling or human antenna effect?

I injected a 90 MHz signal into an electrical cable via a signal generator. And I used a spectrum analyzer to measure the signal strength of 90 MHz at the other end of the cable. Then I found the ...
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39 views

What is and how to measure the tuning port capacitance of a VCO

I was asked to check all the specifications of this Voltage Controlled Oscillator. I might have an idea of how to measure all the parameters except for one, the Tunning Port Capacitance. I think my ...