# Questions tagged [capacitor]

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

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21 views

### Difficulties with capacitor circuit analysis

I have been given this question by one of my lecturers and have been having difficulty with it. I was wondering if anyone could help me. In the circuit of Fig. 1, switch SW1 has been closed, and ...
53 views

### How does the voltage doubler work at the startup?

I have no particular interest in power electronics but I am always impressed by such clever circuit solutions as the Greinacher voltage doubler. The idea behind it is so clear and intuitive that it ...
29 views

### Calculating the size of a capacitor in a sample and hold circuit

Question: In sampling system the sample rate is 500 Ms/s with an input signal of range of 1 V peak−peak and a clock jitter of 1 ps rms . A performance of 60 dB is required for all signals the Nyquist ...
46 views

### Difference between “|Z|” and “Resistance” in capacitor datasheet?

I'm shopping for capacitors, and I expect good capacitor datasheets to have a graph of |Z| (the magnitude of the capacitor's impedance) as a function of frequency. I was confused when I looked at ...
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### What should I use to filter noise from 5V power supply with multiple consumers

I want to create a PCB board that would have: input - 5V wall outlet USB charger or for example MeanWell Din power supply output - 3 usb ports that would be used by RPI-like devices. (5V 2A max each)...
74 views

### How to identify the value of an unmarked SMD capacitor on a PCB?

I have an unmarked SMD capacitor on a PCB and I want to identify the value of this SMD capacitor. I have an LCR meter (BK880) and I want to use it to measure directly the capacitance of this SMD ...
24 views

### Electrostatically charging a capacitor with varying amounts of charge

I'm working on a project that will measure charge, in the nanocoulomb range, of some device powered by some DC power. I'm planning on using a capacitor, a 1 nF, as a means of measuring this charge. ...
39 views

### So i've been trying to repair my mom tv tube, but idk the problem is [closed]

So i have check the setting on the timer tv, and i disable it but, it does keep turning off every 15 - 20 minutes and if i turn it on again the times it goes off come shorten and shorten. Is it ...
84 views

### How is a capacitor in series with a resistor and capacitor in parallel calculated?

How do you calculate this circuit? I would like to calculate both the voltage, current and charge progression of those three components seen as one part as well as their individual voltages, currents ...
41 views

### Select a decoupling capacitor

I have a simple ESP8266 circuit that detects as pulse when a reed switch is open or closed - nothing fancy. I have anti-bounce code configured and everything typically works as expected. Hopefully ...
37 views

### Input Capacitance in LM 2596 Step Down voltage regulator

What is the significance of the input capacitance (680 uF) (uF = microFarad) at the input of the LM 2596 ? LM 2596 is step down voltage regulator. Please refer: http://www.ti.com/lit/ds/symlink/...
41 views

### How can I calculate the sparks when I discharging a big capacitor?

Several years ago I've tried to find answer to this question but I couldn't find the answers. I hope you help me. Because my job I have to discharging constantly "big" capacitors ( 400 vdc, 300 ...
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### Capacitor choice for full discharge [closed]

I'm looking for deep cycle capacitor. It will be fully charged and discharged with 1 Hz frequency. I intend to use discharge current of 300mA and charge current around 100mA. Capacitance is around ...
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### Capacitor constant power charge, constant current discharge curve

I have an (ideal) capacitor that is simultaneously being charged through a DC/DC boost converter (assumed constant power $P_{in}$) and discharged through a linear regulator (assumed constant current ...
28 views

For a simple active RC integrator shown above, what is the effective capacitive load when output is open-circuit. I think it would be the integrating capacitor, $C_I$, because of the virtual ...
80 views

### Will a capacitor draw charge/current if it's not feeding a load?

I have a number of capacitors connected in parallel, as in the following circuit: simulate this circuit – Schematic created using CircuitLab If the switch is open, will the caps still draw ...
2k views

### Why is the AC coupling capacitor always 0.1uF or 0.01uF in high speed transceivers?

As I know, high speed transceivers always use a 0.1uF or 0.01uF capacitor for AC-coupling. ...
47 views

### Capacitor Current–voltage relations conceptual doubt

I understand that a capacitor stores energy on the form of voltage. However, looking at the equations for the current and voltage on the capacitor, we have the following: I was thinking here that if ...
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104 views

### How to find voltage across a capacitor?

I was given this problem in a basic engineering circuit analysis class. I really don't know where to start.
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### WS2813 weird noise and blink led behavior after power supply power off

I am connecting my 1m 60 led WS2813 led strip + esp32 to a 5v 30A power supply (which i bought in past for other project). The led strip is working fine but when I power off the power supply, the ...
100 views

### Supporting SMT electrolytic capacitors in high vibration environments

I recently experienced a situation where an engine ECU failed. The post-failure analysis showed that two capacitors had broken loose from the board due to stress from vibration. I have replaced the ...
505 views

### Is there any connector for SMD components

I want to fine-tune the resonance of multiple LC-circuits with hand made inductors(coils), and SMD capacitors (NP0 type). Currently, I am tuning the resonance frequency by soldering and desoldering ...
45 views

### How the capacitor charges in this circuit?

I have been working on a kind of edge detector, and I would like to be guided about how the capacitor will charge in this circuit. when I don't have any transistor I could easily calculate the ...
86 views

### Placing a polarized capacitor in place of an unpolarized one

The following circuit contains an unpolarized capacitor I only have access to polarized ones, with the same ratings as the unpolarized cap. If I were to implement the circuit, should I place the ...
69 views

### Which side of this board is the capacitor polarity indicating?

In this capacitor slot, which side is the negative and which is the positive? I've never seen this symbol before. I'm assuming the bottom is positive but want to make sure. Thanks!
50 views

### I have a AC motor with 3 wires. Black, red and white. How can i connect the capacitor and to power supply as shown on the diagram?

Please help me to understand the diagram attached. I have a motor with three wires. Black, Red, White. and a Capacitor with 2 wires(both Black). 1. How to connect the capacitor to the motor 2. How ...
71 views

### Why are zener diodes not used for capacitor balancing?

Why are zener diodes not used in parallel with electrolytic capacitors for balancing purposes? Large electrolytic caps generally have a large leakage current (~3mA) which results in large losses in a ...
278 views

### Capacitor Impedance ESR vs Frequency Curve

Yageo's SMT capacitor datasheet lists the ESR vs. Frequency Curve show below: Note that impedance (Z) is listed in units (W). How can this be understood? Why is impedance seemingly not measured in ...
134 views

### Switched-Capacitor Bank Question

Consider the following setup: Capacitors C1, C2, C3, C4 where C1 = C2 = 2C and C3 = C4 = C. All the capacitors in the bank have their top/positive plate connected together at the common central node. ...
38 views

### Subtleties of Boost Conver (Step-up Converter)

simulate this circuit – Schematic created using CircuitLab Generally Boost Converter fault happens in my workplace and difficult to find the problem of converter. So I try to understand the ...
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### Capacitor Charge Sharing

Consider the following circuit Capacitor C2 is charged up to 1V from an external source before-hand. The top plate of C2 is connected to the bottom plate of C1. The top plate of C1 is at a voltage of ...
45 views

### Capacitors in Series - common node

I'm a bit confused on the sign of charges in circuits like these. The bottom (negative) plate of C1 has -Q charge and the top plate (positive) of C2 has +Q charge. However, these two plates are at ...
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### When to use X1 or X2 capacitor?

I've a simple circuit where I need to detect AC voltage presence via a microcontroller (ESP32). The ESP32 is a 3.3V device, and requires (worst case) 2.8V to consider a logical one on a GPIO. I'm ...