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

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2answers
45 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
27 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 ...
0
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0answers
26 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 ...
3
votes
1answer
88 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 ...
-1
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1answer
71 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 ...
0
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0answers
37 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 ...
0
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2answers
89 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
22 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: $$ ...
0
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1answer
36 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
votes
1answer
65 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
votes
2answers
151 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
73 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
votes
1answer
60 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
votes
1answer
54 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 ...
0
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2answers
50 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 = ...
3
votes
1answer
78 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 ...
0
votes
1answer
47 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
152 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 ...
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1answer
54 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
55 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 ...
10
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4answers
786 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
27 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
votes
1answer
51 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
votes
3answers
297 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
98 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
53 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
148 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
85 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... ...
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1answer
178 views

Have I damaged my multimeter by applying voltage in resistance mode?

I have an VC97 digital multimeter. In resistance mode, I applied the multimeter leads to a battery with a 4.2V charge. I did this twice, and also did so in capacitance mode. I didn't notice any ...
0
votes
2answers
55 views

Measuring small (and small changes in) capacitance

I would like to measure the capacitance between two random pieces of metal. Also, I would like to monitor the changes in such capacitance as people walk by those metal objects. Can a cheap ...
1
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2answers
114 views

Physics explanation of charging time by increasing dielectric constant

I am having a problem understanding in physics of the relationship between charging time and dielectric constant of a parallel plate capacitor. I'd like about physics aspect not based on time ...
0
votes
1answer
64 views

Understanding the Difference Between Two Capacitance Sensors

I'm slowly beginning to understand more about how these work thanks to answers I have received on this site. I believe one area of confusion for me has been I've looked at two differently designed ...
1
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1answer
85 views

Can I use any capacitor for a 2 phase AC motor?

So recently I got my hands on an old pump motor, unfortunately the connection diagram is missing. I have already determined this is a 2 phase motor, and that in order to make it work I need a ...
0
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1answer
82 views

Design challenge: Detect finger-to-finger touch with nothing in between

I'm trying to build something quite challenging and seem to be getting nowhere. Maybe you'll help. I'd like to detect a touch of two naked fingers with no materials or sensors in between (simple ...
1
vote
1answer
75 views

Capacitor Help -> Will stacking of dielectric and metal foil increase capacitance?

I'm new to this forum, so forgive me if I am missing something. I am building a capacitor, and I want to know if stacking dielectric and metal foil will increase the capacitance, and if so At what ...
2
votes
1answer
107 views

aluminum foam capacitor

Sorry if this question is in the wrong community but anyway, why don't people use foam aluminium for capacitors? Its got a large surface area to my understanding (however probably not as much surface ...
0
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1answer
61 views

Power factor correction AC motor

Four 240v, 50Hz, 16kW motors are installed in a factory. Each has a power factor of 0.86 lagging and efficiency of 78.2% while running. Determine the shunt capacitance required to deliver unity power ...
-1
votes
0answers
18 views

Electrometer mode of universal amplifier [closed]

Explain why a high resistance is used in electrometer mode. A voltmeter can also be connected to amplifier but what is the use of high resistance in universal amplifier electrometer mode. The circuit ...
4
votes
2answers
131 views

Supercapacitor with a rated voltage value greater than 2.7V feasible?

I've been researching into the development of electrical power units for Automotives (motorsports in particular, as I participate in my Uni's Formula Student team) and have started by looking into the ...
2
votes
5answers
189 views

Why is charge the same on every capacitor in series?

Why is the amount of charge on every capacitor in series equal, regardless that capacitance values of capacitors are not the same? What really happens here so they are the same? simulate this ...
-1
votes
1answer
53 views

What is my capacitance? [closed]

I have a current measurement of 300mA on an MCU evaluation board. If my power supply is 19V or 12V what capacitance do I need to use in order to limit the voltage fall to 5V?
1
vote
1answer
67 views

Why is the input pin to my multiplexer considered a capacitive load?

I am currently using CD74HC4067 multiplexer in my design. I had trouble with my input signal and therefore conducted an experiment by measuring the input resistance of my multiplexer as the frequency ...
2
votes
2answers
576 views

Using an Arduino to measure wire capacitance

I wanted to use an Arduino as a capacitance measurement device for a coaxial wire. I started at measuring the wire capacitance using digital multi-meter UT58B. I turned the knob to 2 nF and then ...
0
votes
1answer
310 views

smallest possible length of copper wire, where I can measure capacitance via multimeter

I am a new highschool physics instructor and I want to show to my students the basic concept inside capacitors and how they work. I plan on showing them 2 simple copper wires side by side , ...
1
vote
1answer
69 views

How to detect the changes in capacitor?

I have a capacitor in the picofarad range. That capacitor will change slightly ±5 picofarad. How can I detect that change? I used two parallel plates (about 5cm gap) that gives 18pF.
1
vote
1answer
77 views

Is it possible to get an exponential capacitance curve from coded dip switch

I have a capacitor that controls frequency for a specialty IC with the relationship \$F \propto 1/C\$ I want to be able to get a number of frequencies in evenly spaced intervals. Currently I have a ...
1
vote
2answers
140 views

How is the electrical bus capacitance for I2C trace calculated?

i am trying to learn how to calculate the bus capacitance of an I2C tree with a master and multiple slaves. For example, in this document from TI, it shows how to calculate the value of the pull up ...
2
votes
3answers
75 views

High capacitance electrical capacitors

Are high capacitance electrical capacitors capable of storing energy instead of using a battery. If so would they be able to hold 7 kws of usable energy for domestic home use?
0
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3answers
74 views

Solving Vout for a differentiating op-amp with added resistor?

I searched through old posts and didn't find a direct answer to this - there were practical explanations but no circuit math. I am to solve the \$V_{out}\$ value for a differentiating op-amp. I know ...
2
votes
1answer
75 views

How to measure parastic capacitance of a trace

I have a 24 MHz, crystal on my board and datasheet of IC defines the load capacitance between 5-9pF. The reference design I follow don't use any load capacitor. My traces look like this: shorter ...