Questions tagged [capacitance]
Capacitance is the ability of a body to store an electrical charge
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Thoughts on storing electricity in water vapor
for an engineering class I had to create an electrical energy storage device and I began thinking about thunderstorms (I think it was a cloudy day) and how they create lighting. I know it's not ...
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1answer
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Voltages and charges with regard to ESD
My question is with reference to this question - ESD protection using a capacitor
I am unable to grasp the relation between charge, voltage, and capacitance, although I can understand all these terms ...
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2answers
66 views
Capacitor measurement in existing circuit
I am searching for the cap load formula of C2 of the following circuit:
In the end I want to be able to determine the capacitance of C2 through the ADC-IN voltage.
The unknown part is a driver which ...
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4answers
115 views
Reasoning behind equations in analysis of electrical circuit
I am currently studying the mathematics textbook Nonlinear Dynamics and Chaos by Strogatz. As part of an example, I am provided with the following electrical circuit and accompanying explanation:
...
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1answer
88 views
Discharging a capacitor without a resistor
Is the following circuit considered un-safe? That is, can a capacitor be discharged with a bare wire connecting the two terminals, or should some resistance be applied? Why or why not?
Additionally, ...
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1answer
38 views
capacitance vs impedance measurement
I've been trying to design precise distance measurements similar to the digital caliper or dial micrometer for my CNC project by capacitance sensing between prob and base metal. I can connect base ...
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1answer
40 views
What is the gain of this capacitance measurement circuit?
To sense the capacitance value of a sensor, I found the following circuit.
My knowledge on analogue electronics isn't that great, so I'm not sure how I'd determine the gain of this circuit.
Vo is ...
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1answer
73 views
Input and Output capacitance
I have understood that there are both input and output parasitic capacitances in real op-amps, but I am trying to understand why they are there.
As for the input capacitance, there are two types:
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1answer
44 views
How to determine parasitic capacitance of a diode according to the datasheet?
In order to do simulation, I would like to determine the parasitic diode capacitance of a diode according to this datasheet, when the information is not present into the datasheet... (Simulation model ...
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66 views
Find capacitor in AC RLC circuit, so that power dissipated in resistor is maximum
I didn't find a topic on my question, that's why I'm creating one (but if there is one, don't hesitate to tell me).
I am stuck on an exercise with AC circuits (RLC): The exercise tells me that I have ...
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3answers
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Understanding capacitance in oscilloscope probe tip
I am trying to understand the capacitance and resistance in oscilloscope probe tip.
In the above attached image, that 9Mohm resistance is used for that 1x and 10x setting that divides the input ...
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1answer
56 views
How do I calculate the capacitance in this circuit?
I can't find any source online to how I can calculate the capacitance in this circuit, the previous questions seem solvable, but any help would be appreciated thank you!!
Here’s a formula I found, ...
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1answer
58 views
Can Network Analyzer measure Impedance, Conductance, Susceptance or is there a device that does all?
I want to measure the impedance, conductance and susceptance of a large metallic object (about the size of a boat), and I want to know if it is possible to measure using Network Analyzer. If yes, are ...
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1answer
52 views
Why does the high capacitance of a metal oxide varistor affect sensors and signal sensitivity?
I want to know why the high capacitance of metal oxide varistors affects sensors, signal sensitivity.
How does capacitance affect sensitivity ?
If we add a low capacitor in series will the total ...
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3answers
77 views
Are charge and voltage in a capacitor always directly proportional, regardless of structure?
Capacitance is said to be a constant, and is defined as \$C := \frac{q}{V}\$. I have been unable, however, to find an implementation-independent way to show that charge and voltage are directly ...
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0answers
31 views
Capacitance calculation of comb-drive actuator
I just want to make sure that I am performing this calculation correctly...
From this COMSOL study, I gathered the following info...
$$C_t = N\frac{\varepsilon_o\varepsilon_rl_ot}{d}$$
$$C_f = \...
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0answers
26 views
Capacitance of parallel wires in checkerboard pattern
Below is a cross-sectional view of a 4x4 array of inter-meshed cylinders...
$$\begin{matrix}\Huge\circ && \Huge\bullet && \Huge\circ && \Huge\bullet \\\\ \Huge\bullet &&...
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4answers
990 views
Why do we have to discharge the capacitor before testing it in an LCR Meter?
LCR meters charge and discharge the capacitor to find out the capacity value (by using the time constant formula.)
I wondering why a charged capacitor(even few volts) can damage the LCR meter?
Why do ...
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1answer
61 views
Total Capacitance In A Circuit Along With Other Electronic Component
I know it may sound stupid but having thinking across my mind with the basic knowledge I've already have with capacitance(series and parallel), I've been wondering on how to get the total capacitance ...
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2answers
69 views
Voltage output across purely capacitive voltage divider when PWM/Square wave signal is applied?
Having some trouble with understanding the voltage output in time domain across a capacitive voltage divider when applying a square wave from 0 to 5V? It can be assumed that the capacitors have some ...
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0answers
52 views
Question about a capacitance to voltage converter
I followed a MEMS course made basically of seminars. The examination is just the presentation of a scientific article. I've been given an article in which the Authors present a MEMS inclinometer ("...
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1answer
84 views
Help Identifying a capacitor WITHOUT a capacitance meter and no markings? [closed]
I have a DELL 2408WFP Monitor purchased in 2009 that I am currently using right now. I have an issue with that monitor where it runs hot and shuts off after a certain period of time. This could be due ...
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24 views
How to choose replacement capacitor/inductor in a simple RLC blackbox?
Assuming there's a circuit that we can't see but we can guess how it works based on what it's made for. We know (or just are pretty sure) it's an RLC circuit with no digital parts. From what I've ...
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1answer
40 views
Finding Equivalent Resistance - does order matter?
Conceptual question:
When you have a super complicated circuit, does it matter which node you start at when finding equivalent resistance? How about capacitance?
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2answers
119 views
If I have 3 batteries 100mAh 200mAh and 300mAh what the total charge in series?
I have a tiny questions about the total charge the 3 batteries (E=1,5V) in series.
I compute that way:
\$ Qtotal = C_{eq}\cdot 3E\$
\$1/C_{eq} = 1/C1 + 1/C2 + 1/C3\$
\$1/C_{eq} = \frac{(C1C2+C1C3+...
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1answer
61 views
How does relative permittivity decrease with frequency while capacitance doesn't?
As I understand, capacitance is $$\frac{\varepsilon A}{d}$$ where ε is the absolute permittivity. If the capacitor's dimensions are kept constant, then a change in ε with frequency should mean a ...
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1answer
88 views
What is the equivalent capacitance in this circuit?
I was trying to find the equivalent resistance here, but I do not know how to deal with the empty wire. Do we just simply ignore it? What happens to the charges, current and to the last capacitor in ...
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1answer
52 views
What does worst-case gate capacitance mean in a MOS transistor?
I have searched the statement; MOS worst-case gate capacitance in various forms but no avail.
Keep in mind I'm a student. The course I am taking has no reference material. With note slides with ...
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3answers
76 views
The Behaviour of Capacitors’ Plates
Recently I have learned about the behaviours of capacitors are as follows:
When connected to a voltage source the voltage on the the plate on the positive side begins to rise slowly until it reaches ...
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1answer
18 views
How do I measure material specific(volumentric) capacitance
I'd like to test electric capacitance of different powders pressed into solids.
I want to know if my procedure is correct.
First I connect a wire between the material and a ground (ex. radiator) to ...
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1answer
40 views
Cable for remote capacitance measurement
I have an application, where I want to detect proximity of conductive materials (including humans). The idea is that I have a series of conductive sense strips and I measure capacitance between each ...
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1answer
65 views
MOSFET as a Capacitor in IC
I was reading in a book that it is often possible to realize a certain capacitance in Integrated Circuits by exploiting the Gate Capacitance of a MOSFET. I read that the main disadvantage of this ...
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51 views
How is the lever position read?
I am servicing a truck rig. This is the system that reads the "turn light switch" and "windscreen wiper switch".
I would like to understand how the image plate 1 reads each position of the levers. On ...
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2answers
76 views
Maximum capacitive loading for DC-DC converter - how to calculate?
Following this answer I looked into the datasheet of the OKI-78SR-5/1.5-W36-C and see the following:
In general the requirement is clear for me: resistance at the start event must not be too low for ...
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2answers
79 views
MEMS Oscillator not running, why?
For the latest iteration of my prototype, I replaced a quartz oscillator with (what I thought would be) a drop-in MEMS replacement: the DSC6013CI2A-033.0000.
It is suppling a 33 MHz clock to a TLC5955 ...
0
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0answers
46 views
Snubber capacitor Voltage rating
I am designing a switching circuit for celing fan (max 80W/230VAC). This is basically relay based switching.
I planned to add snubber circuit to reduce the back emf.
I got a resistor value of 100&...
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1answer
78 views
AC coupled sinewave
How can I see in this picture that the signals are AC coupled?
Does not AC coupled means that the DC offset is 0 and the sine is centered to the origin?
Both signals have an offset from what I can ...
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0answers
24 views
Measuring Cov, Cdb of MOSFET
I am working through problem 1.27 of the book, Analog Circuit design where I am trying to measure Cov, and Cdb, as shown:
http://analogicdesign.com/students/netlists-models/chapter-1-netlists/problem-...
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2answers
149 views
What is conductor to conductor to shield capacitance?
I am using 6.5 ft (2 meters) BELDEN 9154 shielded twisted pair cable for a sub 1 MHz application and I wanted to make a model of the cable for some simulations. The datasheet of the cable lists two ...
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4answers
84 views
Capacitor Selection for high voltage
I have a circuit which has about 10 kilovolts input and I want to store that voltage on a capacitor. I calculated and drew the circuit but I am now using an 18 nano farad capacitor at the end. I ...
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3answers
151 views
Parallel Capacitors with different voltages
Let's consider a capacitor precharged to 5V.
Now immagine to put it in parallel with a capacitor which has no charge. What does it happen? They reach a voltage in the middle? Does it depend on their ...
0
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1answer
71 views
Pass Transistor: discharging of the capacitance
let's consider this pass transistor logic:
Let's assume that the MOSFET is always active (CK = high for a N-MOSFET). Now, immagine that at the beginning Vin = 10V and Vx = 0: the capacitance Cx will ...
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1answer
114 views
Collector-Base capacitance in simple FM transmitter
Here is a schematic of a simple FM transmitter. I understand that this work in the following way: the sound picked up by the mic is translated into a voltage at the base of the Q1 transistor. As the ...
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3answers
69 views
Cap touch measurement using digital pin?
I have previously used dedicated touch pins and connected them across an electrode and been able to easily detect touch. Usually in such a case one wire directly from the pad to the dedicated touch ...
0
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2answers
83 views
RC circuit intuition
How to intuitively guess the output waveform of a rc differentiator to a ramp input? I know it will be a constant value if RC is very small but that's from calculation. How can I intuitively guess it? ...
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1answer
2k views
Capacitors with a “/” on schematic
I'm looking at a schematic for an old turntable that I am needing help on when viewing the capacitor values. All of the polarized caps will have 2 values written next to symbol i.e. ...
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1answer
74 views
How to run electricity through metal wire to (safely) act as a stylus?
I’m trying to make a robotic arm draw a lowercase ‘i’ on my iPhone’s drawing app without lifting the stylus. The robot arm bit is another story, my current focus is trying to make a stylus out of a ...
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57 views
Is diode reverse recovery time related to diode capacitance?
The title. Is there some relationship between the two parameters? For example, fast diode recovery time indicates low capacitance, or even farther, can one be calculated from the other? Thank you in ...
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0answers
87 views
Opamp isolation resistor calculations for a capacitive load
I want to add a capacitive filter for pulse shaping to the output of a transimpedance amplifier using an OPA847. Without the filter, the amplifier works great. With the filter, I get some ...
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Test circuits for testing input and output capacitance of an NMOS spice model?
As the title states, I'm having trouble finding resources online for confirming the capacitances of an N-MOS spice model. If there are any resources someone could point me to to learn more or test ...
