Questions tagged [capacitor]

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

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Explanation of capacitor usage in this N-MOS application

I'd like to understand why capacitor is used in this circuit instead of connecting PWM pin directly to N-MOS. How does Q3 have HIGH reference with no direct connection? What kind of advantage I have ...
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Will capacitor in high pass filter pass high frequencies while it is blocking low frequencies?

I thought that capacitors will only act as a conductor while is is being charged and once fully charged it will not conduct any more. I know that current does not actually pass through the capacitor ...
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Phase difference between electric and magnetic fields of EM wave in a conductor?

When an EM wave travels inside a conductor , we see that there is a phase difference between the Electric and magnetic fields within the conductor. The magnetic field lags behind the E field and this ...
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3answers
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Simulating charge-discharge of a capacitor in TINKERCAD

I have been using TINKERCAD circuits for a while now, and I have been able to simulate almost every basic thing in circuits. But when it comes to simulating the charging and discharging times of a ...
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1answer
28 views

Replacing 10uF tantalum capacitors with X7R in ADM2587E circuit

I'm working on some device with isolated RS485 based on ADM2587E transceiver with integrated high frequency isolated DC/DC converter. This IC is a bit tricky if you need low EMI, because DC/DC ...
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Diagnosing short inside Nintendo Switch [duplicate]

My Nintendo Switch suddenly wouldn't turn on or charge. Nothing on the screen, no reboot/reset trick I have tried worked. I often used a normal USB-C instead of the official charger, which might have ...
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The effect of grounding a simple circuit?

Suppose I have a simple DC circuit consisting of a battery of voltage V (no internal resistance assumed), and a resistor (resistance R) connected in series by conducting wires. Because the wires are ...
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Voltage rating of capacitor for SSR controlling motor (blinds) 275AC (630DC) V rating? or 600V(ac)?

I need an RC snubber to protect my SSRs that control my blinds (reversible motor). I've read a lot about which capacitor I should use (my SSR spec sheet even states to use a voltage between 400 and ...
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54 views

Why does RC circuit create 180 degree phase shift in current?

I was playing around with capacitors in LTspice today to grasp a better understand of how they shift the phase of voltage and current. I created what would be considered a 1st order filter. See image ...
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1answer
84 views

What is the Thevenin equivalent of this low-pass filter?

I am trying to calculate the Thevenin equivalent circuit of this low pass filter however, I have never done it with an AC input and am getting very confused. $$R = 100\Omega ; C = 2\mu F$$ $$Vin = ...
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1answer
37 views

Picking a capacitor for HCMS-29xx display

I've got a HCMS-3972 LED display, and I'd like to play with it from Arduino following this tutorial. The diagram and schematics show a capacitor, but does not specify any details. The data sheet says ...
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Where is the electric field in an \$LC\$ circuit?

Suppose we have an ideal \$LC\$ circuit with an open switch at time \$t=0\$ where the capacitor is initially charged to a voltage \$V\$. The instant the switch is closed, the typical \$LC\$ ...
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Can C3 in the schematic be polarized?

Here's the data sheet if it helps. https://www.cui.com/product/resource/pdqe15-d.pdf The DC\DC converter is an isolator unit so the left part of the circuit doesn't us a traditional GND, which leads ...
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4answers
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How does this RC pulse generator circuit work?

In this video from Ben Eater, he uses an RC circuit to create a push-button "write-pulse" generator for his EEPROM (discussed around the 14 minute mark) that ensures the write pulse fits ...
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VPC0820 Li-Ion Capacitor how to understand the 97% Self Discharge (V) parameter

Does anyone know what does the self-discharge parameter mean? I know what self-discharge is, but what does over 97% mean?
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Can a floating capacitor terminal be used to collect electrons?

I want to collect charge from an electron beam source. For that, I'm proposing to put a floating capacitor with its bottom terminal floating and directly exposed to the electron beam gun. The top ...
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1answer
59 views

PCB routing of parrallel capacitors with different values (Based on STM Nucleo64 dev board)

I have been recently trying to understand how the STM32 ICs should be routed on PCB, in particular parallel capacitors of different values for power design. I have come across various suggestion about ...
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Capacitors current options

About capacitors the formula Ic = C*dV/dt refers to the displacement current or to the current which charges/discharges the capacitor?
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1answer
199 views

How do I determine the resultant permittivity of two different dielectric materials in a cylinder capacitor?

I am trying to calculate the density charge of the inner cylinder in the above picture. If there was only one dielectric I would use the following equation: $$ \frac{q_{enc}^f}{L} = \frac{2\pi \...
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Why does the dynamic error of a low pass filter decrease when adding a load at the output?

I have this anti-aliasing low pass filter where R = 100Ω and C = 3.62μF. When the input has a frequency of 50Hz, Vin(t) = sin(2π*50t), I have worked out the dynamic error and found that the maximum ...
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201 views

Transient buildup of capacitively coupled transistor amplifier

I'm trying to understand the following section from "Communication Circuits: Analysis and Design" by Donald T. Hess: Here \$W(t)\$ is defined by $$W(t) = e^{\frac{q(v_i(t) - v_{imax})}{kT}}...
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101 views

Use different capacitor for subwoofer

I got a broken subwoofer from a friend of my dad. It has a build-in amplifier. During testing we came across some problems, most of which we solved. But during these tests, out of the blue, something ...
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1answer
49 views

Regulator output capacitors placement

I'm using a TPS63060 regulator and according to its manual there should be typical 66uF capacitance on the output, please see this screenshot: In order to achieve that I'm planning to use three 22uF ...
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1answer
55 views

Electrospray Deposition

I recently got a new project to work on, an Electrospray Deposition setup. Basically, it consists of a needle that contains a liquid, a electrode and a high voltage source. The needle is positioned at ...
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Diode and capacitor part of a circuit: I don't understand it

I'm fixing an electronic device (a Sony Discman D-50) but there is a part of the circuit that I don't fully understand. This is the part of the circuit I'm talking about. I've highlighted the part I'm ...
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SMD - identify two parts

I think one is a 10uf capacitor 10-20l. Second one no idea.
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Input Ripple Voltage and Output Ripple Voltage for Capacitors

I'm working with Buck converters and Boost converters separately. Can someone tell me the reason why the output ripple voltage (and current) exists in the Output Capacitors and how does the input ...
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61 views

Single value capacitor or two different in parallel for filtering the power supply for microcontroller

I am trying to design power supply for the STM32F446 for my PCB. I wonder if I should stick to the Datasheet of STM32F446 Page 71 and use two capacitors or be careful about it and maybe just use one ...
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How do i solve a circuit when a capacitor is between in op amp inputs?

I am quite confused with this circuit. Most circuits I have seen don't have a capacitor between the op amp inputs. I tried to write out the differential equations using nodes, but I can't find enough ...
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55 views

Is it possible to run a small circut off the power that is output from a unpowered headphone/speaker?

So I'm currently dreaming up my first PCB project! I would like to make a 1/4 audio switcher for my current audio setup (two outputs 1 input) I'm fairly new to electrical engineering I'm about 3 years ...
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Bulk Capacitors

I'm looking at a design that is using 2x220uf bulk capacitors (while other 2 are placeholders). these capacitors are used in Validation Platform for some CPU. I was wondering if I can replace these ...
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Calculating the capacitance for a voltage multiplier circuit

Recently, I've been asked to create a voltage multiplier, with an output voltage \$Vo = 5*Vi\$, where \$Vi\$ is the peak input voltage. This was accomplished without much issues through the schematic ...
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1answer
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Is this a capacitive start motor and can i start it with this capacitor [duplicate]

I salvaged an old motor out of a air conditioner and I want to know if it's a capacitor start motor if I can start it with the capacitor I have and how to start it. I included pictures of the motor ...
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1answer
64 views

Generate a higher-than-power-supply voltage with capacitors

I want to design a circuit which is able to generate 8-10V from a power supply of 5V by chargin parallel caps and switch them to series connection (by using transistors) so they reach the desired ...
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1answer
48 views

Capacitor not charging up

Hello electronics experts, I am basically a computer engineer but because of a robotics project i am in a need of designing small ups for few seconds backup ( Approximately 8-10 seconds ) but facing ...
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Is this a capacitor start motor and can I start it with a microwave capacitor [closed]

I salvaged an old motor out of a air conditioner and I want to know if it's a capacitor start motor if I can start it with the capacitor I have and how to start it. I included pictures of the motor ...
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1answer
52 views

Why are parasitic capacitances the main factor for limiting high frequency performance of active devices such as transistors?

According to the Wikipedia article, the reason for the limit of frequencies in which transistors operate is the parasitic capacitance. But I don't understand why this is so. Wikipedia article: ...
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How are this voltage source and resistor (separated from each other by a capacitor) re-imagined as a resistive voltage source?

I'm trying to implement a wave digital filter from this research paper: Emulation of Operational Amplifiers and Diodes in Audio Distortion Circuits R. C. D. de Paiva, S. D Angelo, J. Pakarinen, and V. ...
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What are the capacitors between the IN and OUT pins of a TDA7318 mixer chip for?

Fiddling around with my TDA7318 mixer chip, I've found a strange contradiction between the suggested "test circuit" cited in the manufacturer's datasheet, and the schematic published by ...
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Capacitor Lifetime

Can anyone some sample calculation on how to calculate the lifetime on an Aluminum Electrolytic capacitor who's Endurance value (Assumed as Lifetime value is 2000 hours at 105degC). The manufacturer ...
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1answer
87 views

Help decode/identify/guess this blown ceramic capacitor?

My monitor's backlight died (can still see screen with torch). Found a blown ceramic disc capacitor. The problem is it's partly exploded over the values. I'm hoping people here might have a better ...
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Capacitor for reducing voltage drops

I use gsm module, which makes current bursts up to 2Amps (maybe slightly more). That causes voltage drops about 0.5V on my power supply (I use lipo battery), and than device hangs up or starts ...
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Are fluorescent tubes dangerous?

I'm disassembling a Sega GameGear. The capacitors inside are all rated 50v or lower, so it shouldn't be hazardous in that regard (I will discharge them anyway just to be sure). However, the metal ...
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Crystal oscillator ECS-2520MV connection

First time connecting this type of oscillator and need some help as too how to connect it. The oscillator I will be using is the https://ecsxtal.com/store/pdf/ECS-2520MV.pdf Does this seem correct to ...
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Calculate the finger position on a Capacitive touch slider

When building a Capacitive touch slider like the picture shows, I know when finger tip touches the metal slider it would create a apparent sensor capacitance is increased by the introduction of a ...
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Why recommend tantalum over ceramic capacitor for voltage regulator? [duplicate]

The LM1117 voltage regulator datasheet recommends using tantalum capacitors on the input and output. What is the reason for this? What advantage does tantalum have over a ceramic capacitor? A 10μF ...
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61 views

Part Identification, Board says C32 but it looks nothing like a capacitor and has 6/9 marking on it

First, I understand that you have to remove the components to fault find but this is just something to play with. It's an internal HDD SATA adapter to USB3 with additional 12VDC for 3.5" HDDS. It ...
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LTspice simulation with capacitors

I have this circuit simulated in LTspice : simulate this circuit – Schematic created using CircuitLab Here is the graph: Why does the current flowing through R2 do that thing in the beginning (...
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2answers
82 views

Issues with kitchen fan - how to salvage? [closed]

In my kitchen there is a fan to extract air in case it smells during cooking to not make the whole appartment stink like food. When I turn it on, it looks like it is working. But after a bit of time, ...
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Capacitor parallel to resistor question

I have this circuit and now I am stuck. I don't know how to continue to find i1(t), i2(t) and i3(t)

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