Questions tagged [capacitor]

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

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22 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. ...
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So i've been trying to repair my mom tv tube, but idk the problem is

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 ...
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34 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 ...
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37 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 ...
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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/...
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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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38 views

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 ...
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27 views

Effective Capacitive Loading of Active RC Integrator

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 ...
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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 ...
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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. ...
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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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How is the (dis)charging process of capacitors in series calculated?

How is the (dis)charging process of capacitors in series calculated? I know that $$C_{total}=\frac1{\frac{1}{C_1}+\frac{1}{C_2}+\frac{1}{C_3}+...}$$ $$Q_{total}=Q_{1}=Q_{2}=Q_{3}=...$$ $$V_{1/2/3}=\...
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51 views

Using a cap to predict the presence of a pulse via voltmeter

I have a pulsed power supply that provides 250v pulses with a pulse width of 2 uS and a frequency of 10 Hz. However, I'm unaware of the polarity of these pulses. In order to detect the polarity of ...
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67 views

How to determine capacitor values for common emitter amplifier?

Looking at this circuit: I understand that the two capacitors are used to filter DC. I don't understand how it is possible to know what values (in terms of farads) would be required for these.
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RECOM Input/Output Filter Calculations

I am new to dc/dc converters and was hoping for some input from the community to see if I am on the right track. I two questions with the first being related to the data sheet EMI filters and the 2nd ...
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Circuit design - please explain to me the usage of these capacitor and inductor

I am studying this circuit, but unable to understand why they put capacitor C30, C33, EC4, inductor L3 on their current place, and their value, i keep searching on google for decoupling capacitor, ...
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57 views

P-Channel Mosfet switch and Capacitor Discharge on Drain

I'm using the following circuit with a P-channel mosfet to switch the positive line to a transceiver. I want to keep the transceiver grounded and switch it off to stop current draw from the battery. ...
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90 views

I am trying to understand the behavior of a pulse

I have this pulse This is the observed data. I have a LTSPice model that needs to be matched as close as possible to the observed data I need to match the e area of from 350 to 500 ns, because the ...
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2answers
63 views

Use of Ceramic capacitors in HV system

When I opened the supply board to the detector (Geiger Counter), I got the above circuit. The detector uses a gas-filled tube with a central wire at high voltage to collect the ionization (charge) ...
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1answer
97 views

Why do some analog circuits use a FET with shorted drain and source?

Why do some analog circuits use a FET with shorted drain and source? Depending of the type of FET, it may either act as a capacitor or a diode? It each case, why not just use a cap or a diode? Below ...
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43 views

Charge distribution on switched capacitors

Computing the voltage and charge of these capacitors in series and parallel, I come up with a situation in which I couldn't explain why the circuit is behaving as it is. The circuit is the following: ...
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74 views

Thoughts on storing electricity in water vapor [closed]

for an engineering class I had to create an electrical energy storage device and I began thinking about thunderstorms (I think it was a cloudy day) and how they create lighting. I know it's not ...
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53 views

Reverse Polarity in rush Protection 2 p fet parallel

after reading those links : Reverse-polarity protection P-channel MOSFET Optimal method for multiple MOSFETs for LED driving with a shared power rail Parallel MOSFETs and this pdf : ...
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4answers
56 views

Capacitive Divider for DC signals

I was running the following LTSpice simulation to see if a capacitor would divide a DC signal, this results in the following As you can see, it works fine and obeys the cap divider formula of C1/C1+...
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51 views

Help identifying components in schematic for HT9032

I'm new to electronics and hoping to make a caller ID interface using an HT9032C or HT9032D to do the Bell 202 FSK demodulation. However, I'm having a problem understanding the example application ...
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Plotting impedance of an inductor and capacitor in series

The capacitor and inductor are in series, which means that the equivalent impedance of these two elements is $$Z_{LC}=\frac{1-\omega^2LC}{j\omega L}$$ So for the three cases I got the following ...
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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 ...
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99 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 ...
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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 ...
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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 ...
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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 ...
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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!
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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 ...
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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 ...
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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 ...
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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. ...
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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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27 views

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 ...
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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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64 views

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 ...
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42 views

Thermal Noise Sampling on Capacitors

[ From Marcel Pelgrom's Analog-to-Digital Conversion ,pg34] I was reading this example from the noise sampling section and I am bit confused. Why does he say that the noise contributions from each ...
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36 views

Are PCB spreading inductance and loop inductance the same thing?

Hi there, there is a mention of power/ground net spreading inductance in the Figure 1. I'm assuming this is the same as PCB spreading inductance. If so, is loop inductance the same thing here? Or ...
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115 views

Reasoning behind equations in analysis of electrical circuit

I am currently studying the mathematics textbook Nonlinear Dynamics and Chaos by Strogatz. As part of an example, I am provided with the following electrical circuit and accompanying explanation: ...
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1answer
512 views

Can Computer Motherboards Work Fine Even With A Damaged SMD Capacitor/Resistor?

I'm asking this because when I was replacing my laptop battery, I accidentally hit and broke/disconected one SMD capacitor off the board, then I turned my laptop on, it made some weird electrical ...
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Pulsating a vibration module using purely an analogue circuit

I have a simple analogue circuit I'm trying to create. Essentially it's a 1.2V power source that pulsates a vibrator motor - without a 555 timer. When the circuit is closed, uninterrupted current is ...
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128 views

Why does the capacitor need to be small in RC filter circuits?

Hi there, in this example, it mentions that "One should choose R2 to be as close to 100kohm (to make the C2 small)". My question is: what are the reasons for C2 to be small? Other than the fact that ...
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37 views

Help with simple beginner circuit

I am hoping someone can help me with a circuit idea I have. I am wanting to build a door sensor with a reed switch and an esp8266. I was thinking to keep it low power when the Reed switch closes the ...
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1answer
97 views

Ceramic capacitor 4kHz sound

I have an LDO (TPS7A4101) which has two 10 uF, 50 V ceramic capacitors on the input. The LDO is generating 3.3 V, which is used by MCU to drive the LEDs. When the system goes into standby mode, the ...

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