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

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What is the minimal capacitor (capitor type/size/capacity) needed to fool a capacitive touch screen?

Say I want to provide a device (completely batteryless of course, and detached from any human touch) the capability to immitate a touch on a capacitive screen (Galaxy S6 here). I know I just need some ...
1
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0answers
42 views

What does the electric field for twin capacitors in series look like

I know what it looks like for a parallel plate capacitor, but not for two in series. I'm not currently sure if the field goes constantly from outer plate to outer plate or somehow "pauses" over the ...
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0answers
31 views

Simple schemes of variable voltage to constant current converter [on hold]

I am quitte new in electrical engineering. Can anyone give simple schemes of a converter of variable voltage into constant current (AC to DC). If it is possible, describe also the main advantages and ...
3
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1answer
211 views

Why is the load voltage greater than the supply voltage in an AC circuit?

I was playing with electronics and testing the equation: $$X = \frac{1}{2\pi f C}$$ where \$X\$ is the resistance of the capacitor, \$f\$ is the frequency, \$C\$ is the capacitance. The supply is ...
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0answers
52 views

What is the best capacitor for oscillator circuit working at 20.000000 MHz

I am making an oscillator circuit working at 20.000000 MHz. The IC (NJU6321) needs 0.1uF capacitors. What is the best capacitor for this application? For example, mica, tantalum... or which brand?
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1answer
20 views

Induction Motor Problem

I have an induction motor running hot and slow in the direction it's supposed to but when I change the lead wires so it runs in the opposite direction it runs as it should. Is there any reason as to ...
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2answers
38 views

Importance of phase angles when analysing AC circuit

Freshmen EE circuit. Resistance, inductivity, capacitance are given and effective value of voltage. No phase angles are given. When calculating complex power, may I assume the phase angle of the ...
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1answer
76 views

Voltage Doubler capacitor types

I've got a virtual isolation transformer by connecting two 12V transformers at the secondaries, so the input to my circuit is an isolated 120VAC (US). I'm creating a 2 level Greinacher style voltage ...
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2answers
114 views

Audio Grade Capacitors - Marketing Hype or Better Technology

I have been reading a lot about audio grade capacitors lately, and I cannot find very good information about them. I have read many posts from different sites saying that audio grade capacitors are ...
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1answer
56 views

Correct design for large contactor circuit?

After some advice here I'm wondering if this is the correct design of my circuit. I'm now using a SSR as the control device to the contactor. The diode, I believe, should not only protect the SSR ...
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28 views

AC, diode & capacitor PD question [on hold]

Initially 240V rms mains voltage is connected between terminals A and B in the circuit above. You can assume that the capacitors and diodes are appropriately rated to work at this voltage. When the ...
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1answer
34 views

what is the difference between the capacitance values 225j and 225k x rated

PLEASE what is the difference between the capacitance values 225j and 225k x rated capacitors?
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53 views

Resistance to use with an LED to check if capacitor has been charged

I'm currently using this basic circuit to charge a capacitor I have: Now, I have three power sources which I use: 9V, 12V and 18V. I am using this capacitor to produce sparks to ignite hydrogen. ...
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2answers
66 views

Voltage regulator question

I have made a portable device charger with a 5 volt voltage regulator(7805-TO220 package),a 9 volt battery and a few capacitors.The problem is,when I connect the charger to a certain device(whose ...
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0answers
47 views

capacitor charge balance technique [closed]

In buck converter only inductor current changes and capacitor voltage remains same in capacitor charge balance to achieve optimal dynamic response for buck converter undergoing rapid load change how ...
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0answers
43 views

At what voltage do ceramic chip capacitors actually fail?

I have a circuit which uses a couple of ceramic chip capacitors (1uF, 0805, rated at 100V). What voltage would they likely fail at? In other words, what is the typical degree of overvoltage they ...
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1answer
34 views

High side and low side driver

Is there a specific design for filter capacitors other than selecting a voltage value higher than the supply value,and choosing an appropriate capacitance value??
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1answer
59 views

Using capacitors to supply peak current

I hope this thread is allowed. Based upon my previous topic, which turned out to be the exact opposite of what I needed to accomplish, I have a few questions. I have a 240W 24V Supply: ...
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0answers
50 views

Can I use a capacitive divider to run an AC/DC converter from a higher voltage than its rating?

Suppose I have an AC/DC converter rated to run from 120-240VAC, and I want to run it off 480 VAC. I think I should be able to put two capacitors in series as a voltage divider, and run the converter ...
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3answers
78 views

Transistor feedback loop

In an attempt to create a single transistor flipflop I made this : The Idea : When the base is triggered by a pulse ,current starts flowing from collector to emitter . From the emitter it divides ...
3
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5answers
638 views

Can a charged 120v high voltage capacitor really kill you? [duplicate]

recently I have been hacking few psu and have to deal with some high voltage caps. It sort of scared me, but thinking about it, what is the chance of it really killing me. Is it safe to touch one ...
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4answers
102 views

Transistor capacitor circuit . need help

This isn't working as expected. It should work like this: the led should stay on after pressing push button for one second. Although when I press push button once then led stays on for 4-5 minutes and ...
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2answers
78 views

Help understanding electron flow throug coupling capacitor

Experiment 12 from my beginners book Make: More electronics is instructing me to build the following circuit..... I apologize for posting the whole circuit when my question has to do with just a small ...
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2answers
88 views

What limits physical size of capacitors and inductors becoming really small?

For same capacitance C or same inductance L, one wishes to shirink the physical size of capacitors and inductors (by whatever methods - shrinking down the size of wire, etc.). What limits size ...
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1answer
58 views

why discharging capacitor voltage in a rc circuit is positive? why it should not be negative?

During discharging, the direction of the current is opposite to the original current direction(source current).so the current is negative. likewise the discharging voltage direction is also opposite ...
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1answer
44 views

dc blocking capacitor materials

I'm building a Tesla coil and part of my schematic is a 4.7uF PP MKP Capacitor and at the moment i don't have one. Luckily enough, I have other capacitors of equal value but not material. So I was ...
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3answers
419 views

Voltage dropping capacitor doesn't work?

I connected a voltage dropping capacitor in series with 220v AC supply and I measured the output voltage and it was 220 v too. I was expecting to get a voltage that is less than 220 volts. Did I make ...
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2answers
181 views

Difference between battery and capacitor?

Can capacitor acts like power supply, in which situations? How related are charge/discharge time of battery and capacitor? Why battery has longer discharge time compared to capacitor? Why we cannot ...
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2answers
47 views

Is there a virtual ground in this op-amp?

Consider an ideal differential operational amplifier whose circuit looks like this, Now in this circuit diagram it is given that, the negative terminal is at 0v. But if I give a sine wave as input ...
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1answer
56 views

Capacitor grounded between 2 resistors

This is part of a segment of a design I came up with using schmitt triggers as relaxation oscillators. The picture below shows the 4 possible states of the circuit at any given time. Basically, the ...
2
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1answer
76 views

is it safe to have hot wire connected to ground (metal case, shield) via a capacitor?

I have opened a psu, and I saw a small capacitor is connected between one of the ac inputs and to the ground/shield. We don't have ground in our ac outlet, so a hot 110v ac line could be connected to ...
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3answers
75 views

I need load capacitors on crystal?

Using external PLL clock Multiplier ICS501A The crystal is http://www.txccrystal.com/images/pdf/ab-automotive.pdf I need load capacitors on crystal ?
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1answer
54 views

Transformer Current Limiting

I Rewired A MOT (Microwave Oven Transformer) To have an Output of 40V and a center Tab With No load the primary Gets HOT really fast. I measured the current draw with no load and it pulls about 10 ...
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3answers
63 views

ESR of Ceramic Capacitor

I have been doing a bit research on ceramic capacitors, as I need one for the output of my synchronous buck converter. And as its very common that ESR is not straight forwardly given in the data ...
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2answers
71 views

Where to add a capacitor

So I have a small circuit that I made to flash some led's in sync with my music. It's just a signal from my speaker going into the base of my 2N3903 transistor and the ground of the led is being ...
2
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0answers
96 views

Is it right to apply superposition theorem to the RC circuit with non-zero initial capacitor voltage?

I'm having confusion with applying superposition to simple RC circuit with non-zero initial capacitor voltage. Consider a simple RC circuit series connected with voltage source of step voltage ...
2
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5answers
131 views

Inserting Capacitor into CIrcuit causes LED to fade - Why?

My components are 2x 1.5 V batteries 25V 2200uF capacitor 3v Led copper cables My circuit looks like the following. simulate this circuit – Schematic created using CircuitLab My ...
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0answers
48 views

How bootsrap capacitor work in a power amplifier?

The foremost reason why a bootstrap capacitor is used in a power amplifier is to increase the output voltage swing to the power supply. Theres a relationship between resistor R4 and output voltage: ...
6
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3answers
158 views

How do I safely discharge this capacitor with broken wire?

My electric lawn mower won't start, upon inspection some wires got loose and damaged by the motor. It's a 20µF 500V capacitor. Normally I would try to short the pins with a screwdriver, but as you ...
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3answers
160 views

What are coupling and decoupling capacitors?

I have come through many places stating capacitors as coupling and decoupling capacitors, but I can't understand what is meant by coupling and de-coupling capacitors? Can anyone explain me what they ...
4
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1answer
57 views

Current Ripple in Ceramic Capacitor Selection

I need to choose a ceramic capacitor (ESR<10mOhms, 5VDC) for my buck converter application, whose value should be around 300uF. The reason for going for a ceramic capacitor is the low ESR they ...
2
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1answer
134 views

Why inductors lose inductance when connected in parallel?

Generally I can't arrive due to why inductance lose inductance when connected in parallel. If two capacitors are connected in series, the distance between the plates of a capacitor increase and thus ...
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1answer
58 views

Why do we ignore parasitic capacitance in dc analysis of transistors?

Consider a transistor that has parasitic capacitance of the order of pico-Farads. Then at low frequencies, consider 10Hz $$X_C=1/(2\pi f C)$$ \$X_C\$ will be in the range of giga-ohms. ...
2
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1answer
307 views

Can massive ammounts of 0603 SMD 1uF ceramics displace power caps?

Edit:Warning: there's an error in one of my assumptions in this question, which more or less invalidates it. See Tom Carpenters answer. I'1m designing a switched mode power supply, and of course need ...
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0answers
28 views

EDLC Cyclic Voltammetry: Current peaks keep rising

I am running tests on some EDLCs using cylic voltammetry (sweeping from 1V to -1V) and for some reason the current peaks are gradually getting higher with every sweep. This doesn't make a lot of sense ...
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1answer
48 views

what size or type of supercapacitor bank would be needed to run a TURNIGY ROTOMAX 150cc electric motor? [closed]

What size or type of supercapacitor bank would be needed to run a TURNIGY ROTOMAX 150cc electric motor? Spec.: ...
0
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1answer
41 views

Installing a USB-A Port on D-Link DIR-300NRU B7 with Ralink RT5350F Chipset [closed]

I am writing to enquire about the installation of a USB-A port into the existing but soldered pins on DIR-300NRU B7. The board is given below: The USB pins are located on the bottom right. The ...
2
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2answers
109 views

Help me to understand the simplest voltage multiplers

I attached a picture of the Villard circuit bellow. I can't seem to understand why the capacitor stays charged-up. Since I = CdV/dt, a capacitor finishes being charged at the crests of the voltage ...
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3answers
55 views

How to measure temporary drop in voltage with meter

What's the easiest way to measure the period of time between the "peaks" when a 5V DC signal goes from high to low to high? I'm trying to debug a power-loss problem, and one of the solutions I'm ...
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1answer
68 views

Circuit similar to current divider

This is a circuit with a general, unspecified logic gate fed by a battery. The series \$ L \$ and \$ R \$ represent the wire which carries the current from the battery to the logic gate. ...