Questions tagged [capacitor]

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

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Cause of Current Spikes at Zero Crossing in LC Circuit Connected to 50Hz Mains

I set up a simple experiment where I connected 8x680nF 450VAC polypropylene film capacitors in parallel across a 250VAC, 50Hz mains supply. The capacitors, nominally at 640nF each, have an equivalent ...
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Thyristor blowing up in a coilgun

I am making six stage coilgun. I know that the optocouplers are switched in the diagram but the thyristors keep blowing up. They are blowing up randomly. That's my fourth thyristor I have replaced. ...
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How to charge a 2200uf capacitor to 59V in around 100ms from a 12V battery?

I need to charge a 2200 µF capacitor to 59 V in around 100 ms from a 12 V battery. This converter needs to be at most 35 mm wide. This requires the use of either a boost converter or a dc-dc flyback ...
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Initial condition across capacitor - RLC

The switch has been in the original position for a long time and is flipped at t=0 (apologies for my drawing skills) I am trying to find the initial condition across the capacitor. I am confused ...
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Replacing MOS parasitic cap with external cap. Why does it differ from internal?

This is a circuit which has parasitic capacitors: ...
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What is the most efficient way to detect if AC mains is live for interfacing with a microcontroller?

I want to implement an electrical mains level detector to interface with a microcontroller the simplest and most efficient way possible as this circuit would always be on. I’m trying to detect when a ...
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re connecting a capacitor to a single phase fan motor

Firstly please forgive my ignorance but at 80+ I find it difficult to follow some of the technical jargon as this field evolves. I am trying to repair an industrial fan motor to be used as a blower ...
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Capacitor going to input of op-amp ruining ramp rate

I have this IC which creates a linear voltage ramp proportional to the input voltage based on the capacitor on the output in parallel to ground. I then have to do some analog computation using op amps....
Kieran Clifford's user avatar
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Circuit that turns on an LED and turns it off after some time

I want to create a circuit that turns on an LED when a switch is flipped and automatically turns it off after some time. I use a capacitor for the timedelay. Because I want it to be able to be reused ...
Ron Beton's user avatar
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Finding the current value when capacitor is connected parallel [closed]

How to find the I_B current value if the initial voltage is 600V and capacitance is given as 5000mF.
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Comparison of two methods used to calculate capacitance

I need to compare two potential methods used to calculate capacitance, but I can't find the names for them to do some research. The first method: Placing a capacitor in a circuit with an 800 Hz ...
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Capacitor "blocking DC" in a low pass filter [duplicate]

If we imagine a basic lowpass filter, the AC components from the non perfect DC from VIN passes the capacitor and down to ground, meanwhile "pure" DC flows to VIN. If we take a basic closed ...
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What is this capacitor marked F 103?

I am trying to learn how to identify old capacitors I have. I haven't been able to crack the search "code". I tried testing with my MESR100 ESR meter with no luck. Just says OL. Help finding ...
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Is this a miniature capacitor?

I have literally 1 million of these. How are they attached and used? Are they capacitors? Are they something still used?
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Location of transformer

This is for a POE application. The inductor is in net with the capacitor, as the first attached image shows. I moved this inductor from the previous design bottom of board to its new location. Can ...
Wes Ellgass's user avatar
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Identification of marking on capacitor

Understanding markings as a beginner. I am getting educated on what electronic items do. I have no experience and want to learn. I was not able to find the info I am looking for on the general web. <...
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Timer circuits - difficulty analyzing

I'm looking for timer circuits without 555 IC and trying to understand them. There are some examples that seem easy to understand, but cannot wrap my head around the others. simulate this circuit &...
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What is the value of this SMD capacitor?

I am not an electrical engineer. I can sometimes solder SMD components that I know are bad. Can anyone tell me the value of this capacitor?
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Concentric Cylinders: Measured Capacitance Contradicting Theory

We have two concentric cylindrical rods in the configuration shown below. They are held isolated by two 3D-printed PLA endcaps. The capacitance can be modelled as concentric cylinders using the well-...
s0ggyj0hns0n's user avatar
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Issue with LED and capacitor circuit

I have recently downloaded and am familiarising myself with LTspice, and to do so I started with a basic circuit. I had never used a scope prior to this and thought a capacitor discharging to an LED ...
Smi Jay's user avatar
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2 answers
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Aluminium electrolytic capacitors in an AC circuit

Looking through the datasheet for the TPA3123D2, I have noticed some confusing symbol usage and positioning. From my understanding, aluminium electrolytic capacitors can only be 'charged' on the ...
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1986 truck running rough and intermittent fault codes. Faulty capacitor? [migrated]

My 1986 truck is running rough and has fault codes that come and go. I think the electronic engine control module may be the culprit. I removed it and one of the capacitors has odd markings on the ...
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Test circuit for a solar panel used to power a supercapacitor

I was hoping to power a device with a supercapacitor that would provide power when there isn't light available, so essentially I just need the solar cell to charge the supercap as fast as it would ...
zenizenitsu's user avatar
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Biased Clamper Circuits

I have been tasked to design a clamp circuit to clamp the negative extreme of a periodic input waveform to −5 V. I can use diodes, zener diodes, and resistors of any values required. I will assume a 0....
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0 V across motor capacitor terminals, but resistance is 20 Ω. Is the capacitor dead?

It is a 36 μF, 440 VAC, 50 Hz rated motor running capacitor, used in a single-phase motor. AC source is 240 V, 50 Hz. The motor has stopping working. I want to know whether it is due to a faulty ...
Cinverse's user avatar
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Make a 0.5 HP, 3-phase motor work with single phase voltage with capacitor [duplicate]

I have a MGM Varvel's SM71B4 AC motor which runs on 3-phase that comes out of a Schneider Electric's VFD called Altivar ATV12H037M2. The VFD has failed and doesn't show the input voltage, so I decided ...
Akash Patil's user avatar
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How does a capacitor coupled voltage transformer (CCVT) and spark gap work?

What is the actual purpose of a capacitor coupled voltage transformer in a substation? What I do know is that they offer low impedance to the very high frequency signal, so it does not get into the ...
RiFF RAFF's user avatar
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How to find out whether capacitor is the fault for failed single phase motor?

Single phased motor rated for 220V, 50Hz isn't working. I want to know whether is it just due to a failed capacitor or is the motor itself is damaged. The capacitor looks clean from the outside; no ...
Cinverse's user avatar
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101 views

Charge Capacitor at 5V from 3.3V Microcontroller Pin

I must come up with a circuit that is able to charge a capacitor to 5V that I can drive through a GPIO of a microcontroller running at 3.3V. The capacitor is in a different device and has a leg ...
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Why do we need a small external gate to source capacitor for a MOSFET drive circuit?

I have a question regarding a MOSFET half bridge driver circuit. We always connect a small capcitor between the gate and source of both the high side and the low side switch, typically in picofarads. ...
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How to reliably connect an SMA connector to two pieces of stainless steel?

We are attempting to electrically connect an SMA connector to two pieces of stainless steel to measure the capacitance between them for a school project. In the picture below, you can see the two ...
s0ggyj0hns0n's user avatar
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4 answers
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DC bias of electrolytic capacitor

I see DC bias characteristics for ceramic capacitor where capacitance decreases with applied voltage. I am not finding the same data for electrolytic capacitors. Do electrolytic capacitor values vary ...
NICEGUY NICEGUY's user avatar
2 votes
2 answers
134 views

Simulating square to sine wave conversion via LC circuit results in 200-fold amplification

After watching this video I decided to simulate the following circuit in PSpice: Time domain simulation with general settings, TSTOP of 100 ms and maximum step size of 1 μs yielded the following sine ...
beardeadclown's user avatar
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Should you include multiple low-pass capacitor circuits in integrated IC PCB design?

I have two circuits, one is a POE to 5V, another is an IC for leds. They both include capacitors between 5v and gnd. Should I include the first 5V circuit POE capacitors since it should already be ...
Wes Ellgass's user avatar
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A bit tricky exercise that I'm currently looking for help to solve it

simulate this circuit – Schematic created using CircuitLab The exercise: We switch 200 V as a resulting voltage on two capacitors in series. The charge of the two capacitor is 10 µAs (Q1=Q2). ...
Norbert Kts's user avatar
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Am I correctly interpreting these two fundamental equations about capacitors?

Capacitors follow the fundamental equation \$I(t)=CV'(t)\$, from which we can derive $$Q'(t) = CV'(t).$$ Recently, I read about the equation that describes the charging of a capacitor: $$Q(t) = CV(t)\...
Sam's user avatar
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Calculating the resulting voltage of two capacitors

I've an exercise and I'm not sure that I solved it well, so this is it: What is the resulting voltage of the circuit if two capacitors (3 µF and 6 µF) are connected in series and the energy of the 3 ...
Norbert Kts's user avatar
1 vote
2 answers
121 views

What does really happen when you connect a capacitor in DC series?

To specify what I am asking: How do we even get a current for a moment when the circuit technically never is completed? And what is it that does this? Here I am thinking of a very simple circuit where ...
Lillehavard's user avatar
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4 answers
126 views

How does a filtering capacitor work without a resistor?

Consider the circuit below: A google search said that the capacitors here are used to filter noise/ripples from the incoming and outgoing signals. How are the capacitors able to do this without a ...
Epix's user avatar
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1 answer
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CMOS (Energy Supply of voltage) [closed]

Can someone please explain why, when \$ln\$ is transitioning from low to high, the energy supplied is \$C_{vdd}\cdot V_{dd}^2\$?
Timothy Garott's user avatar
1 vote
1 answer
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Choosing an NTC thermistor for inrush current limiting at 5 V

I'm designing a very simple circuit to enable a Raspberry Pi to power down safely in the event of a power outage. It is comprised of a supercapacitor, a diode to prevent reverse current flow, and a ...
yeah's user avatar
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1 answer
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Why solid state capacitors?

I've been looking through multiple cellphone chargers and I have noticed that they all use solid state capacitor for the output capacitor of the switching power supply (flyback converter). Is there ...
Mohsen Razzaghi's user avatar
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1 answer
31 views

What should be the capacitor values for cascaded voltage regulators?

I have an LD1086DT50TR 5V voltage regulator, which is followed by an LD1117DT33TR 3.3V voltage regulator. The LD1086* datasheet specifies a 10uF capacitor at the regulator's output, while the LD1117* ...
Vishnu's user avatar
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5 V to 3.3 V buck with limited input current and large capacitor to cover current spikes?

We need to design a power supply for a 3.3 V WiFi-device. But there are quite some current spikes during WiFi startup. Using the design below there is a risk the 5 V (250 mA max) supply (not mine) ...
boddeke's user avatar
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Capacitor test mode in ICT

My ICT machine has two capacitor measurement modes on the PCB: Mode 1: Use DC source test method (Figure 1) Mode 2: Use AC source test method (Figure 2) Could anyone please help me with the ...
Hoài Nam Nguyễn's user avatar
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1 answer
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what is single face electrode on F72 series capacitor?

I'm looking at kyocera-avx F72 series capacitor. I'm puzzled at the last 3 numbers of the part number AQ2 or Q2 which say single face electrode. I thought capacitor come with 2 electrode be it ...
sunny's user avatar
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2 answers
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Keep a relay latched for 2-3 seconds using capacitor

Building a simple prototype to keep the relay latched for a couple of seconds after power is removed - so essentially the power to relay acts as the Input signal. This means I have to store energy in ...
tunafish24's user avatar
2 votes
1 answer
68 views

Capacitor polarity marker significance

What I am not asking is what capacitor polarization means, or how to apply it in circuits. Is there any physical significance to whether a capacitor uses its positive or negative leads to mark its ...
shea's user avatar
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5 answers
119 views

To what voltage will this capacitor charge?

To what voltage will the capacitor in the circuit here above charge? The circuit is fed by 10V DC. I=U/R=10/100k=0.1mA Voltage drop on the 10k is 1V. Will the capacitor charge to 9V or to 10V? Someone ...
Jan's user avatar
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1 vote
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Electrical modeling of multilayer structure

If I have a construction of layers wherein the topmost layer is conductive, followed by two different insulation materials in between, and a bottom structural layer that is a partially conductive ...
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