A fundamental electronic component that stores energy in an electric field, commonly used in filtering applications.

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RC circuit How does the current vary after the switch is closed?

in the image below : a quiz from the book "physics for scientists and engineers" in chapter 28 dicussing direct current circuts and RC circuits i need an explanation for the answers for this quiz ...
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2answers
57 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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2answers
59 views

Producing Voltage Spikes from a bench top power supply

I need to test a tantalum capacitor(check if it gets shorted for a spike higher than the rated voltage) and I'm planning for providing voltage spikes to the input connector from a bench top power ...
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1answer
32 views

capacitor selection for power boost

I am working on a simple project which involves in supplying a power to couple of loads using battery and Inverter. The capacity of my inverter is 2000W/ 4000W(10sec). I have connected couple of loads ...
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0answers
27 views

RC network in 12v 50watt halogen desklamp

I'm trying to repair a halogen desklamp that has a transformer based on this circuit: R is a 0.5 ohm 1watt resistor for the main RC network that was blown, I've got some replacements ordered on the ...
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1answer
35 views

Determining which capacitor for a latching pushbutton circuit with NANDs

I am working on a latching push-on/hold-off circuit for a momentary button and I am stuck with determine which type of capacitors to use. The circuit is detailed below (originally from Mosaic ...
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2answers
79 views

Capacitor bank for smoothing full-wave rectification output

I need some insight on the best way to set up the inductor-capacitor portion of our circuit. My goal is to smooth the output from our diode bridge which rectifies the AC current input into DC current. ...
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2answers
35 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 ...
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1answer
75 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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2answers
1k views

Accidentally knocked a capacitor off a laptop motherboard seemingly related to USB

I accidentally knocked off a capacitor from my laptop motherboard (Lenovo Thinkpad S540, VIUS6 LA-A171P board). According to the circuit diagram, this capacitor (C2434) was something to do with the ...
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1answer
35 views

Replacment ceiling fan capacitor [on hold]

I have a ceiling fan that only operates on low speed. I am fairly positive that it is a bad capacitor. It is a five wire capacitor that has 2.5uF/250V, 4uF/250V, and 4uf/300V. I can't seem to find ...
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2answers
89 views

Super capacitor vs. battery

I've made a turn signal system for my bicycle that uses power generated from the wheel. The wheel puts out 0-9v and is irregular depending on the speed. My lights take 3v, originally from two 1.5v ...
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0answers
27 views

DPS298CPA capacitor in 37 pfl 9604h phillips (tv) burnt. What might be a reason? [closed]

First of all I have to say that I am a rookie at this, but I know how to solder, and I have a tester. Now, the problem occured this way, TV was working, then I smelled burnt plastic, so I turned it ...
4
votes
2answers
82 views

When can Self Resonance of a capacitor be a bad thing in bypass and decoupling applications?

Specifically in decoupling and bypass applications, can the Self Resonance frequency cause problems (compared to ideal)? If so, what kind of problems can it cause?
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1answer
38 views

When do I need separate MLCC (input) and AL-ELEC (bulk) capacitors on my SMPS design?

I've been studying the specification of input capacitance for switching converters. I have a related question here that provides more background. In my research into the topic I came across TI ...
2
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1answer
50 views

Is it useful to think of SMPS input capacitance as part of an LC filter?

I'm at the stage of learning about switched-mode power supplies that I'm focused on understanding the role of input capacitance. Just for background, I'm working with a buck topology for this ...
2
votes
3answers
75 views

What do these two omega's say about this filter?

I've got the filter that's given in the picture below, they calculate the pole and the zero of the transfer function but what do these two values for omega say, is it kind of a cut-off frequency? (...
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0answers
37 views

Running a fan off minimal solar power [closed]

I need a little help. It has been over 30 years since I last was in a high school electronics class. I have forgotten much. I have a solar panel. I found that in low light levels I can use it to ...
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1answer
51 views

Identifiying and Cleaning leaked capacitor (which it was not)

Trying to fix a device that has a huge cap that leaked badly. The leak is like molasses. Maybe thicker. And there is around 2 puddles of 2-3 teaspoons each. I cannot clean the thing very well. So i ...
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1answer
44 views

swapping a 1uf 200v axial capacitor for a .9uf 200v axial capacitor

I have a bad axial type .9uf 200v capacitor in the power supply of an old turntable. Can I substitute a 1uf 200v axial capacitor in its place?
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3answers
127 views

Why is the voltage across the capacitor constant?

I've connected a 6V DC voltage source via a 1Ω resistor to a 1F capacitor. I was expecting the simulation to reveal a less constant t-vs-v graph: it would start at 0 and after a while stabilize ...
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1answer
59 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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2answers
67 views

Impedence of 90° out of phase Capacitor and Inductor in parallel

I'm curious as to what the equivalent impedance would be of these two elements. Mathematically it seems that they would have infinite impedance (meaning an open circuit), but this doesn't make any ...
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votes
7answers
278 views

Understanding Lead in a causal system

I've gone through school and done all the work but looking back at it i still don't quite get it. The rule is current in a capacitor leads and in an inductor lags. The inductor makes perfect sense ...
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0answers
83 views

Maximum voltage a capacitor resists?

I'm working on a supercapacitor. The thing is I'm trying to calculate its capacitance by calculating its half life time but I don't know the maximum voltage the capacitor resists. Does anyone know how ...
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1answer
72 views

Oil Function On Leyden Jar Capacitor

When i look into this tesla coil tutorial: www.instructables.com/id/How-to-build-a-Tesla-Coil I that tutorial also explained how to make leyden jar capacitor.He said after pouring salt water into the ...
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2answers
47 views

What happens with voltage phase on the resistor and capacitor in AC circuit?

I'm currently studying AC circuits and I find it difficult to understand phase differences between voltage and current on different components. For example, let's look at this circuit: And here is ...
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2answers
129 views

What kind of elements are these?

I disassembled a LED lamp and it's circuit. My intention is to rebuild that circuit within EveryCircuit app, to understand how it is working. On this circuit I found two elements that are rising ...
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3answers
125 views

Capacitor charge - why a resistance is needed?

I'm wondering why every example of a circuit capable of charging a capacitor has a resistor in it. Why is this resistor necessary?
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1answer
164 views

Why are capacitors with large values are manufactured polarized? [duplicate]

I couldn't find a duplicate-like of this question. I'm also not sure whether this is an electrical engineering question or a physics question. As most of you noticed when one needs to use larger ...
0
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1answer
31 views

RPi Pressure Sensor using Piezo Transducer

I am trying to make a pressure sensor to use with my raspberry pi zero. I would like to avoid making another purchase, so while an ADC or FSR would be easier I would like to figure this method out. ...
0
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1answer
50 views

How to modify this tank circuit to obtain a 3rd order passive band pass filter?

I am very confused about band pass- and band rejectfilters. I have this circuit which represents a bandpass filter. A 2nd order (2 energy exchanging elements) bandpass filter if I am not mistaking: ...
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2answers
280 views

What do capacitor markings in dash-dot stype mean?

I have got a few capacitors in my sortiment which have got dash-dot markings above and below the value code, like this: What do these dash-dot codes mean? Do they reflect voltage rating or ...
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2answers
63 views

What does the 3-figure code below the value code mean?

I have got plenty of capacitors which I do not know the manufacturer of. They are all marked with the 3-digit value code (for instance, "153", meaning 15×103 pF = 15 nF). There is a second code ...
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2answers
57 views

Monitor status of slow-switching (1 second) signal

I need to make a circuit that can look at a signal and turn an LED on or off if the signal is actively switching. The input signal turns off and on for a period of about 500ms, but sometimes will be ...
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3answers
99 views

Using capacitor as a rechargeable battery

As part of my learning of electronics, I'm currently trying to develop my own network of sensors. So far, I've managed to make myself a satisfying small setup : A few nodes, built with an ...
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2answers
70 views

Charging capacitor in parallel and discharging in series

I wanted to use multiple capacitors to step up the voltage in a circuit. A little bit of google searching told me that it is called a Charge Pump. I figured out the charging each capacitor ...
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3answers
87 views

Do capacitors increase voltage?

Just got a (220<-->12-0-12) transformer hooked up with a bridge rectifier and it measured 13 volts DC output from rectifier, but when I added a 1uF capacitor it just jumped up to 20 volts, and same ...
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3answers
127 views

Raspberry pi super capacitor power supply

I'm trying to make a simple ups for a raspberry pi dash cam. The goal is to provide power to the pi for about 10 seconds after the car has stopped running. When the power supply turns off, the gpio ...
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2answers
53 views

How good should the regulated AC/DC power supply filter be in tube headphone amp?

I am building a tube headphone amplifier. I built a AC/DC regulated power supply (220v AC to ~250v DC) but I am not sure about how good is the filter. The filter contains 120uF and 68UF capacitors, in ...
0
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1answer
29 views

Powering a self-drive piezo buzzer with capacitors?

I have a project I am working on where I want to power a "self-drive" piezo buzzer for 20-30 seconds. However, in order to provide the power to this piezo, I would like to ideally use capacitors in ...
4
votes
1answer
103 views

capacitor RF performance

We have a standard SMD 0603 capacitor kit from that I picked a capacitor for use in a 868MHz Antenna matching circuit. I picked this 3.3pF capacitor from the kit. The Q is listed a 1MHz, but I read ...
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1answer
89 views

A question about the argument part of impedance

The definition of impedance is Z = V/I. I'm trying to understand the idea behind the argument part of the impedance concept in a capacitor. First here is what I know briefly so far: I will begin ...
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2answers
79 views

Decoupling and bulk capacitor number and value

I am currently finishing a circuit with TIVA C TM4C123G where the user manual indicate the following: "decoupling capacitor typically 0.1uF in value and should be accompanied by a bulk capacitor. The ...
5
votes
1answer
190 views

How to tell film capacitor type

How do you tell what type a capacitor is, (e.g. MKT, MKP, Mylar)? Most capacitors probably don't have a datasheet. Also, if the capacitor has no markings/code, for example: is it possible to guess ...
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2answers
72 views

Polar capacitors and a lack of jargon

Today I found myself wondering something about capacitors, and though my first reaction was to turn to Google, I also discovered that I don't know how to word my inquiry without getting ten thousand ...
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0answers
85 views

Identifying shorted capacitor on laptop motherboard

Background: My Asus U47A laptop stopped charging or running off the AC adapter. With the help of diagnostic tips on the internet, I found the culprit to be a faulty ceramic cap near the input jack ...
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1answer
39 views

Help me check the values for capacitors in a reference design

I have the following circuit diagram from documentatoin for an MC34167 which I'd like to use in a project. Am I correct in assuming the capacitors are all in pF? which would give me:- 330pF ...
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2answers
76 views

Charge pump circuit with one MOSFET

This is an example of charge pump from MOSFET Models for SPICE Simulation: Including BSIM3v3 and BSIM4 by William Liu. Could anyone explain why \$ v_D = \frac{(v_{IN} - V_T)}{2} \$ here? Why \$ V_T \...
3
votes
3answers
381 views

What is this cap-like part?

I found a huge cap-like looking part in an old parts bin of mine. I tried making sense of its marking and I don't really understand what they mean. I googled for the part number and I found eBay ...