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

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52 views

'How/why' does a human act as a capacitor for a theremin?

I've read that a human plays a theremin by acting as a capacitor, or reducing the capacitance of the theremin. What properties of a human make it act this way? Is there any way of reducing/negating ...
-2
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1answer
53 views

Energy stored in the capacitor increase when the capacitance decrease [on hold]

Help!!!!Energy stored in the capacitor increase when the capacitance decrease.Suggest an explanation for this energy increase, making reference to conservation of energy. Question [paper 3,Q4(D)(ii)] ...
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22 views

Equivalent capacitance for Darlington

In a Darlington pair of BJTs, it is known that equivalent parameters of a unique transistor can be found (\$r_{\pi}\$, \$r_{o}\$, \$g_{m}\$). But what about its capacitance? Is it possible to replace ...
1
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1answer
20 views

How to use BSIM3v3 capacitance for hand calculation?

As you all probably know, capacitances in BSIM3v3 are just the partial derivatives of the terminal charges with respect to the terminal voltages. They are not physical two terminal capacitors. Cij = ...
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62 views

Why does 7.6Mhz signal start appearing?

I am using a reference design that modulates a 8Mhz carrier DC square wave in simple on-off keying at 10bps. I wanted to change the carrier to 125kHz. I took out the 56pF capacitor in C4 and ...
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40 views

MOSFET gate capacitance in strong inversion

This lecture (page 4 and 5) said about gate capacitance of a MOSFET in various operating condition. From the table below, as you can see in strong inversion \$C_{ox}\$ and junction capacitance \$C_{...
1
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1answer
24 views

Channel to bulk capacitance in inversion

This lecture (page 11) said that as Vgs increases further, the inversion layer forms and the channel to bulk capacitance is “shielded”. So the channel to bulk capacitance is 0. Could anyone explain ...
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2answers
62 views

Are parasitic capacitance \$C_{gs}\$ and \$C_{gd}\$ parallel in a MOS?

The picutre below shows the parasitic capacitance \$C_{gs}\$ and \$C_{gd}\$ in a MOS transistor. Can we consider that the two capacitors are in parallel in this case?
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0answers
27 views

RMS current of a circuit driven by a white noise voltage source

Note: I am an applied mathematician, not an electrical engineer, so apologies if this comes across as silly. I am analyzing the following circuit as part of some modeling related to energy storage ...
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2answers
62 views

Circuit to prevent spark from plugging Li-po batteries into motor driver with filtering capacitors

I have a motor driver that handles 2 150watt motors powered by 2 Li-po 12V batteries (connected in series). Obviously, I need filtering caps on my driver so I used 2 1200uF caps connected in parallel. ...
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1answer
47 views

How to calculate capacitance analytically?

Im developing a capacitive sensor of concentric cylindrical plates type.I know its dimensions(length & diameter). How i can calculate its capacitance without using any multi-meter or LCR-meter?
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4answers
60 views

How to measure capacitance of a capacitive sensor?

I've started working on capacitive sensors and finally got one ready(which is concentric cylinder type) but now I need to test it. I have few doubts: Can I calculate the value of capacitance without ...
0
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2answers
37 views

Combining decoupling capacitors for sensitive power requirements in LPDDR

I've been looking through a bunch of designs I found online on LPDDR2 interfacing. What's always confused me is the parallel decoupling capacitors. Why have so many vs just combining that to what you ...
1
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1answer
97 views

How MOSFET gate capacitances (Cgs, Cgd) are calculated?

I have read somewhere that the gate capacitance (Cgs, Cgd) of a MOS is calculated as below: Strong inversion: Cgs=(2/3)Cox.W.L + Cov Non-saturated: Cgs=Cgd=(1/2)Cox.W.L + Cov where Cov is ...
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1answer
65 views

how to determine the exact value of the capacitor for a particular package using the datasheet [closed]

how to determine the exact value of the capacitor for a particular package ? In normal case datasheet of the capacitor generally gives capacitor values withing wide ranges like 120 pF to 300 nF for a ...
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0answers
23 views

How to measure fast transient capacitance response

I would like to measure a fast transient capacitance response of a diode when switching from forward to reverse bias. There are commercial instruments available to do this, such as the Boonton 72 or ...
0
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2answers
169 views

What will increase output volume (dB) on a Piezo Transducer?

I need to achieve 110dB at 25khz from a Piezo Transducer. According to the datasheet, the resonant frequency of the Piezo is 25khz and at 10 vrms it will produce 110dB. I will be using an ...
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0answers
14 views

Duble use crystal speaker for capacitive touch sensing

I like to use a piezo crystal speaker to double as a capacitive proximity / touch sensor while not used for audio. The small speaker is directly driven by MCU digital pins. To accomplish this, I ...
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0answers
38 views

Supercap as dashcam memory backup

I'm working on a raspberry pi dashcam and have a few questions about using a supercap to provide ~10seconds of runtime to ensure the current file is correctly written to disc in case of power failure. ...
0
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2answers
111 views

What happens to current in a RC-battery circuit when you move plates with a square signal?

I use an RC circuit connected in series with a battery. I change the gap between plates of my air capacitor (2 paralleles plates, one fixe, the other one moving with an actuator) so as to change my ...
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0answers
22 views

How to extract complex permittivity from a CV measurement?

I can choose from the following measurements: Z, theta (impedance and phase angle) R + jX (resistance and reactance) Cp-Gp (parallel capacitance and conductance) Cs-Rs (series capacitance and ...
0
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1answer
29 views

Diffusion Capacitance: Forward Bias

Please see attached image. I'm struggling to understand how the book went from line 2 to line 3; it doesnt seem obvious how they did the differential. Thanks
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2answers
46 views

How were values of Vc(0+) and i(1.5ms) found?

I get that by applying source transformation, we get a (0.1*200=20 V) source but shouldn't 0.1 A current be divided into 50 ohm and 100 ohm resistance? Also why i=0 at t=1.5ms?
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1answer
31 views

Miller's Theorem - Input Capacitance

Please see attached image. I've become confused if the answer to this question, which uses Miller's Theorem is correct as it should not be a minus, rather it should be a plus. Please see my working ...
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0answers
27 views

Determine voltage limit from load capacitance limit?

I want to add a NTC thermistor (a.k.a. inrush current limiter, or ICL) to a circuit. But the manufacturer only specifies the following (and I'm giving sample values for the component I'm considering):...
3
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1answer
105 views

How long should 8, 1.5V batteries last for?

I purchased a GPS tracker from Amazon and instead of wiring it to the car battery I would like to simply attach my own power battery pack. I am a complete noob when it comes to electronics and I ...
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1answer
73 views

How must be real transistor model? [closed]

Transistors have some capacitance value. So where do i must put that capacitance when i want to draw real model of transistor. Also second question same about diodes? Can anyone draw simple real model ...
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0answers
38 views

Series Gate Resistor needed at low Capacitance?

even though this question has been answered before for various scenarios, I would like to ask for a generic advice. So I want to drive a certain resistive load from a microcontroller pin. Let MCU be ...
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2answers
92 views

Would the frequency of LED be equal to that of microcontroller

Suppose I have a simple LED driving circuit i.e. an LED and a resistor in series which is driven by a pin of a microcontroller. Now I set the frequency of this pin to say 1Khz, will the LED flash with ...
0
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1answer
23 views

Calculate capacitance i.a. via reactive power

The ampermeter of the following circuit shows 10A (AC) and the voltmeter 220V (AC). Furthermore its known that: $$ cos\varphi=\frac{2}{3} \\ f=50Hz $$ I calculated the following: $$ P=UIcos\...
0
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1answer
37 views

How to get the same output signal but with an increased capacitive load?

I'm designing a CMOS circuit of a VCO and it works perfectly fine when tested independently. Now when I cascade an other block like a divider to it, the output isn't the same as before. Rather its ...
0
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1answer
68 views

Will A Logarithmic Potentiometer Linearise A Capacitor Charge Curve?

I want to use a rising voltage on a capacitor to set more than one trigger points for events via comparators; that is when the voltage reaches a certain level, the comparator goes high. For ease I ...
3
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2answers
153 views

Choosing crystal, strangely narrow requirements in MCU datasheet?

I am making a prototype using the Atmel ATSAM4S2B microcontroller, but I am having trouble choosing a crystal. I need a 12MHz crystal to use the integrated USB module. The problem is, in the ...
0
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3answers
81 views

Does mutual capacitance increase for two positively charged plates when brought close?

My understanding is that any two charge carriers will exhibit what is known as mutual capacitance. That is, there is an amount of charge that can be stored between any two objects, which is called ...
0
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1answer
66 views

What happen if i connect the capacitors with few LED Strip in parallel?

I want to make my LED Strips which connected in parallel to dim out slowly. Therefore, i thought of using few capacitors (in parallel) to make this possible. if i"m using 12V batery as power supply ...
0
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1answer
60 views

I have this timer circuit. Push and release vs push and hold give me different times

I have a timer circuit which I slightly modified from the one in this link I have an image below of what my circuit looks like. My problem is this: When I push my start button and immediately let go,...
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2answers
51 views

Getting the numerical value of a capacitor's impedance

I understand that the impedance of a capacitor is \$\frac{1}{j\omega C}\$. For the circuit above, I have \$\frac{1}{Z_V} = \frac{1}{Z_{V1}} + \frac{1}{Z_{V2}} + j\omega C_V\$ and \$V_V = \frac{Z_V}{...
3
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1answer
91 views

Is it practical to measure an unknown capacitance by measuring its impedance?

I've recently seen some fourth year engineering projects at my school (University of Waterloo) and one that I found interesting was this novel pressure sensor that uses nano silver separated by a di-...
0
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1answer
51 views

Cable-to-cable crosstalk (Capacitative Coupling)

I'm having some difficulty understanding the solution to this question. Compute the cable-to-cable crosstalk due to capacitive coupling in a harness between two cable pairs having an average ...
0
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2answers
179 views

Capacitive touch insulation problem?

I have an "U" shaped metal profile that is 2 meters long each side is 1.5 cm. It is sprayed with acrilic color. and i want to use it as indirect light profile/enclosure for a 12v Led strip. While ...
0
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1answer
61 views

Does this speed controller alter resistance or capacitance?

The attached image is of a ceiling fan speed controller module I brought online. It seems the attached circuit mainly consists of some capacitors. This makes me believe that the 4 different settings ...
0
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1answer
65 views

Sensing a touch of a metal

Assume there is a piece of metal. I would like to identify, with a microcontroller, if another metallic object is touching this piece. I want to apply this for a smart hook that "knows" if a ...
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4answers
829 views

Why do we use two parallel capacitors in a voltage regulator circuit? [duplicate]

C1 and C2 are parallel capacitors and their total capacitance is 1000.1 uF. I think C1 is ...
0
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1answer
28 views

C4D capacitively coupled electrode sensing - circuit simplification

I am trying to make a detector to pick up small changes in capacitance. Basically both electrodes have a common ground and are closely spaced. One is driven by oscillator at 0.1-1MHz and the other one ...
0
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1answer
53 views

How to find the sketch energy of the capacitor (let's say versus time) with the q-v plot shown below?

I wonder what is the plot of the energy of the so-called capacitor,it's will be 0 except in 2 and 3 that is a delta function but when we want to calculate it's energy we don't know the exact value of ...
3
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3answers
303 views

If the voltage doesn't kill you, does the current capability matter?

Trade electricians often work on live household circuits carrying 120V AC. I've gotten shocked by accidentally touching such hot wires often enough to recognize the 60Hz AC buzz. Fortunately, human ...
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2answers
100 views

Find the equivalent capacity of this circuit [closed]

I wonder how to obtain the equivalent capacity of the circuit below.I think adding a voltage source and using KVL would be a nice idea but I don't know how to apply it.any hints would be appreciated.
3
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1answer
54 views

Glove Breach Detection

I'm trying to design a circuit that would be fitted inside large plastic gloves. That when the gloves are cut the circuit produces a signal. Currently I'm considering having a metal (probably ...
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3answers
180 views

Definition of equivalent capacitance [duplicate]

I know that equivalent capacitance of multiple capacitors in series is $$ C = \left(\frac{1}{C_1} + \cdots + \frac{1}{C_n}\right)^{-1} $$ and in parallel is $$ C = C_1 + \cdots + C_n. $$ But there are ...
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2answers
97 views

Capacitance node calculation

I am trying to calculate the equivivalent capacitance to ground of a 3 phase LCL filter with capacitors to ground. Inductors removed from circuit as I assume they will be ignored by the meter... ...