# Questions tagged [capacitor]

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

3,374 questions
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### Series capacitors; negative voltage

Interesting observation today; I set up a series stack of 4 cheap electrolytic capacitors (10V 220u) and after about 5 mins of applying 30V the lower most cap had settled at -300mV. The other three ...
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### Finding the energy over the capacitor in DC

I tried using Thevenin to solve this and found Rth = 3 and Vth = 12 but this is way off the correct energy of the capactor (the energy is 4J).
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### Help Identifying/Decoding Ceramic Capacitor

I am having a difficult time identifying a high voltage, ceramic capacitor that I need to replace. I've tried at length to research this myself to no avail. I am hoping that someone out there can help ...
628 views

### Understanding charge and discharge of a capacitor

I feel bad at this point. This will be my last post about it, however, I will explain myself more clearly and more transparent so everyone doesn't need to guess my issues. Never been so confused ...
385 views

### Schematic help - Unknown capacitors for Raspberry Pi project

I'm recreating a Raspberry Pi project and ordered a custom Pi hat to follow their schematic. The only issue is that it doesn't have all of the information. I've emailed the creator but am yet to hear ...
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### What are the considerations for designing a capacitor bank?

I am trying to understand capacitor banks and capacitor discharge, and how to work out what I need to generate a short pulsed current. If I would like to use capacitor discharge to produce a sudden ...
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### PWM Switching and Current measurement

I have the following circuit: This circuit is created in simulink. It has a voltage source (Vs is 36V, Rs is the source's internal resistance, at 0.001Ω). Resistance R is 1Ω. I want to control the ...
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### Deriving the Integral Voltage-Current Relationship of a Capacitor

I am having trouble understanding the derivation of the capacitor voltage equation in my circuits textbook. Here is the process they followed from the textbook My confusion is: when the initial ...
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### How do I go about solving this and finding the value of v(t)?

I'm very sorry if the solution turns out to be very basic, but I'm a very recent student and my teacher is less than happy to help. edit: sorry for not posting my attempted solutions first. Here is ...
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### Using ground plane for bypass capacitor and package size

I'm working on a breadboard debouncing PCB and starting going down the rabbit hole of bypass caps. Here's my layout and the debouncing ICs recommended layout (found here on the datasheet): Here's my ...
26 views

### variation of thickness of dielectric layer for different textile-based capacitive pressure sensors

For my thesis I am working with textile-based capacitive pressure sensors and I am struggling to see how much variation in thickness of the dielectric layer you can have before you have noticeable ...
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### Transformer duality model with capacitor

I want to know if it is possible to transfer power through the instruments using capacitors? As you know instruments such as Marx generator actually increase the power but we aim to have sth to work ...
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### How to calculate the current flowing through a capacitor

Let's say that there is capacitor set up in a circuit: the capacitor's value : 1 F the source : 20 V How to calculate the current used by the capacitor , what equations should be used ?
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### Calculating the oscillator frequency

I am trying to calculate the frequency of the internal oscillator, in order to go through the design procedure listed in the datasheet. The problem is that it gives me answers that contradict the ...
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### What should be the voltage rating of bootstrap capacitor?

BST_1P is the bootstrap capacitor connection pin for high-side gate driver of TAS6422. In the datasheet it is suggested that, this capacitor should have minimum rated voltage of 16 V. What is the ...
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### Contact a very small area (impedance matched)

In my current project, I want to apply a voltage to a capacitor (top electrode on a thin film heterostructure) very rapidly. Since capacitors have their own charging rate \\$(\tau = R \cdot t = R \cdot ...
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### Wouldn't Charge Flow On Power Lines Due to Capacitance

If I touch one line of an exposed power line (say 300 kV AC) and the rest of my body is freely suspended (only in contact with air), am I not forming a capacitor (to ground)? If I am, are electrons ...
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### Ultracapacitor doesn't charge

I am concerned about an ultracapacitor (2.7v, 3000F) that I received today. I set my power supply to 2.5v with a current limit of 1A, then connected a diode to the positive lead such that current ...
121 views

### Is there any difference between voltage drop and voltage across a component?

Voltage drop across a component describes the reduction of energy when current moves through passive elements, is this the same as voltage across? What about for capacitors, technically current does ...
733 views

### Max voltage of capacitor?

Is there a max voltage drop across a capacitor? Or does it always charge up to the same voltage as the supply? If there is a max voltage, then what would happen if the supply voltage far exceeds the ...
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### Non-Polarized Electrolytic Capacitor Replacement

To the best of my abilities, I'm trying to repair an Atari 800XL which was sold as "non working unit". I found a new graphics chip and it's working ok. I though that, since I had it opened up, it ...
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### How to improve this microphone phantom power supply to have better SNR?

I built this power supply for my Schoeps CMT30F vintage microphones: It works, but it's not the best I can expect in terms of SNR. What would do you to ensure the SNR is the best possible? Use 0,1% ...
2k views

### Why does this simple circuit oscillate? (Ekasi oscillator)

Why does an Ekasi oscillator oscillate? From my research, I learned that when this is first plugged in, the capacitor is charging, so the LED doesn't shine. When the capacitor reaches 12v, then the ...
65 views

### Can a coil gun be made with a boost converter instead of caps?

So I’ve been starting to build a coilgun, and I find most designs either have capacitors or are just really bad. But could a high-voltage boost converter (40000v) and a momentary switch not be used to ...
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### How i can make transmission line from inducor and capacitor [closed]

The questions are: How can i make an inductor using transmission line? How can i make a capacitor using transmission line?
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### Home made High voltage Capacitors

I'm building my own high voltage capacitors, for science, and I'm running into an issue. I'm 90% sure what I'm looking at is coronal discharge but I wanted to be certain. The caps are two aluminum ...
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### Modify a 1629 magic eye tube circuit to a 6E5S tube?

I've an EICO 950B capacitance tester with me. It has an aging 1629 magic eye tube. I have a bunch of 6E5S tube with me. Can you guys guide me with the modification? I know the first step to this is ...
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### How to improve an elegant design for an LED dimmer, low-powered with LDO

I am building a sunrise alarm clock. The LED is supposed to get brighter over the course of 30 minutes, then remain fully lit for another 30 minutes, then switch off. I am using a digital pin on an ...
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### Failure Rate calculation based on manufacturing defects (capacitor)

Electronics failure rates typically follow the exponential distribution and models like Prism, Mil-Hdbk-217 or 217Plus (newer) are used to predict failure rates. We are currently in the production ...
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### What is the application of capacitor between Vcc and GND [duplicate]

This is a schematic mo ATmega328P used circuit. It has paralleled two 100nF capacitors between Vcc and GND. (C8 and C9) What is the function of this two capacitors and why they are paralleled?
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### Safety Capacitor Selection

When selecting an X2 safety capacitor what must be taken into consideration. There are only a few types of capacitance ranges and seem to be chosen based on voltage rather than capacitance. Take ...
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### Impedance matching a capacitor load

I am currently trying to impedance match a capacitor as a load. In detail, it is an insulating thin film grown on top of a conductive layer (grounded). We now sputtered small Pt electrodes on top and ...
191 views

### Undescriptive capacitor and inductor values in audio-amp datasheet

I was learning about audio amplifiers and came across the STA516B IC. To my surprise, the example circuits feature some values for capacitors and inductors which seem a bit high for me. So I wanted to ...
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### Finding voltage drop across a capacitor

The circuit below is a part of a continuous circuit : The question asks to find the voltage drop across the capacitor of 2 microF. The values of the resistances and currents are arbitrary. I only ...
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### SMD component list for capacitor

Being newbie to electronics, I'm unsure which SMD component to choose. I'm trying to build a step down voltage circuit using AMS 1117 (5 v to 3.3 v). I want to know the SMD capacitor component (...
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### AT89S52 microcontroller only starts when extra 22uF capacitor touches board

I made simple code for the microcontroller that prints a simple message on the LCD once the microcontroller starts. I arranged my board so that the pull-up resistors and reset resistor (100K) and ...
113 views

### Soldering sensitive components

I am working on a project called LM317 power supply. The schematic is from the internet, and contains the regulator, filter capacitors, rectifier, potentiometer and protection diodes. I designed a ...
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### Source transformation with impedance being inductor or capacitor

I found a presentation that states the following about source transformation when the impedance is capacitive/inductive: While electrical circuits books, like Nilsson's, says: If I transform the ...
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### Using capacitor to protect circuit from split second power disconnects

I have a circuit powered by a 9V battery. The circuit will be subjected to significant vibrations. I want the circuit to not power off if the battery is disconnected for a second. Would a capacitor in ...
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### Is there a limit to the amount of charge that could be stored in any system as a result of the charge particles repelling each other?

Is there a limit to the amount of charge that could be stored in any system as a result of the charge particles repelling each other?
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### What is the error in my circuit in Simulink?

Please see the image below. I get this error when I try to run the circuit on simulink. Series RLC branch and Series RLC branch 1 refer to the two DC-Link capacitors of the inverter on the left side ...
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### caps in series, equivalent capacitance to reduce voltage rating

For example, I need 100uF 60V capacitor for filtering in power supply. DC source is about 40V. But I have 400uF 20V caps. If I arrange four of them in series I got in total 100 uF and each cap has ...
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### How can I change component values in a premade circuit

I do projects quite frequently, but the only problem is that sometimes I don't have the right component, and it takes to long to ship. I heard that some people change the values of their components (...
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### variable capacitance oscillator design vs varicap diode

I have a little project and I am reflecting on going from theory to practical implementation. The idea is simple. Connect a high-speed motor (like an HDD 7200 rpm one) to the shaft of an air ganged ...
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### What will be the behavior of this circuit?

i have a circuit for which i have simulated its output. But i can't seem to understand how it works. Here is the circuit.. simulate this circuit – Schematic created using CircuitLab For ...
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### TV capacitor 54j 6kv swc [closed]

My television (the brand is Philips) died and I'm trying to save it, When I had open it I had see a dead capacitor (54j 6kv swc), the most similar I saw was on Ali express with (54j 6kv), I don't ...
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### AC coupling capacitor in the ground to break the ground loop?

I'm implementing the following audio single-ended to differential converter for an ADC: This is the reference design for the PCM1804 that I intend to use. What would happen if I do this: Would it ...
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### Capacitor in DC DC converter

As part of my circuit, I need to step down voltage from +15V to +-12V. For this purpose, I am using Traco TEN 20-2422WIN. I was going through its application note when I saw that they because of EMI, ...