Questions tagged [capacitor-charging]

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Why doesn’t voltage drop to 0 when a capacitor becomes fully charged?

This is my understanding so far of what capacitors are and how they work, if it helps to answer my question at a level I can understand: A capacitor is composed of two equally sized conductive plates ...
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Joule Thief powered HC-SR501 PIR Motion Sensor & LED string

Following BigCliveDotCom's YouTube video, I was able to build a joule thief. I then built a HC-SR501 PIR Motion Sensor lighting a 4.5v string of LED fairy lights powered by either a 5v wall wart. or ...
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Simple RC Circuit question: how does a precharged capacitor interact with a lower voltage source?

So, I have this simple question to solve, but I am uncertain about some details. The circuit I have to solve is the one on the image below: I have a circuit with one capacitor(C = 1/4 Farad), two ...
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39 views

How to calculate a capacitor's discharge time? [duplicate]

How do i calculate a capacitor with a specific capacitance loaded with a specific resistance discharge time and reach a specific voltage? So let's say i have a 22uF capacitor charged with 12 volts ...
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2answers
85 views

Current flow through capacitor

How does the current through capacitor and resistor network be decreasing from maximum, when the voltage across them is increasing from minimum? And also to my knowledge the charge that's get reside ...
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Charger for a CDI ignition system [duplicate]

Maybe my first question Dc-Dc converter from 12v Input 400v Output was too broad for what I was actually trying to solve, which is why I am reformating my question. I want to charge a capacitor (C=0....
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5answers
2k views

Heat lost in ideal capacitor charging

If we use an ideal capacitor to charge another ideal capacitor, my intuition tells me no heat is generated since capacitors are just storage elements. It shouldn't consume energy. But in order to ...
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2answers
41 views

Active Discharge Options

More and more frequently I am faced with a specification that requires the ability to discharge an output capacitance to a safe level X, in time Y. The circuit I am currently working on is 2000uF @ ...
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76 views

Transfer of Energy from Initially charged capacitor to uncharged Capacitor

I have started to learn about LC circuits, Specifically, I am simulating a case where the initial conditions are where one large capacitor (100F) has previously been charged to 1.3V, considering the ...
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2answers
96 views

Crockcroft-Walton Voltage Multiplier Large Voltage Loss

I have a CW voltage multiplier that uses 30kV, 1nF capacitors and doubled 20kV, 5mA, 100ns diodes (for a total of 40kV). My ac source is a sine wave (viewed on the primary side of the transformer ...
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1answer
41 views

Low power device with high current peak

I'm creating power supply for controller that usually operates with very low power consumption, but sometimes needs high power. To make the situation harder there is "sometimes" external power present ...
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1answer
114 views

LTSpice - Capacitor Charging/Discharging Circuit not working right

I am trying to do a charging and a discharging Circuit. R8 is the load that Capacitor C1 needs to discharge into when P12V_IN is low. My question is Why is Vsolenoid low in the interval shown on the ...
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1answer
43 views

Multistage capacitor charging

I am currently building my first coilgun. I already have MOSFETs rated at 100V, and 50V 470uF capacitors I can wire in series to obtain 100V. I know this voltage will not result in a very high ...
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168 views

Charging a high voltage capacitor with power supply. How exactly?

I have a semi-serious hobby project with a couple of friends where we need to charge a pulse operated capacitor rated to around 4kV with 1500nF capacitance. For this I need a high voltage supply and ...
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55 views

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 ...
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1answer
97 views

How do I charge a capacitor?

So I have a 270uF 350v capacitor that I am trying to charge. The schematic shows a the right size for a 22uF, how do I know what size resistor i need to charge it? What type of transistor do I ...
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2answers
318 views

Solar powered LED via capacitor?

I am building a large garden peice in wood, which I hope to illumine from within, powered by a small, (perhaps 90x65, 6v, 0.6w 100mA as space is limited) solar panel. After testing, I noticed that ...
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3answers
2k views

How to Measure Very Large Capacitance e.g. Super/Ultra Capacitors

I have recently acquired a couple of mysterious ultra/super capacitors from my brother. Apparently he doesn't remember any of the specifications or even brand... To further complicate matters, they ...
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131 views

Marx Generator For Quick Discharge of Capacitors On Inductor

Hello guys! My goal was to charge these two capacitors with a dc generator as shown in the schematic using a Cockcroft-Walton generator which has worked in the lab perfectly. The capacitors are ...
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2answers
792 views

Supercapacitors in series

Can I charge series of 4 Maxwell BCAP3000 supercapacitors with constant current method using an adjustable Power Supply, and exceed the voltage rated for single cell? What I mean is to charge the ...
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3answers
77 views

Capacitor not reaching supply voltage with LED in series

Totally new to electronics here. Without the red LED "charging indicator", the capacitor charges fully to 10V, but with the diode the capacitor maxes out at about 8.42V. I don't understand why the ...
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2answers
285 views

Why is the voltage of a capacitor equal to the voltage of a battery connected it?

I am confused by this question. If we connect a resistor in series to capacitor then the voltage will drop across the resistor and now voltage across the capacitor is less than the source, then why ...
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1answer
265 views

How do I charge a 2100v 0.95uF capacitor? [closed]

I'm trying to make a rail gun, and I am using 4 microwave capacitors for the extra kick but I don't know how to charge them. I would like to know how charging capacitors works and what I'll need to ...
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1answer
78 views

Can someone explain the working of this Surge Suppression Circuit

This is an old circuit which is still being used. I am curious to understand that if 600 VAC is applied to AC side of the three phase rectifier which has diodes, and on the DC output side of the ...
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0answers
71 views

Capacitor for handling startup current of DC-DC converter shows different behavior

I’m using a 5V DC-DC converter to step-up a coin cell (Nominal Voltage: 3V) to 5V which did not work. I suspected that the high startup current of the converter was causing the Cell voltage to drop, ...
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2answers
105 views

Is driver necessary to drive P-FET Buck Converter using Microcontroller?

I'm building a buck converter to charge an ultracapacitor from Hydrogen Fuel Cell. I'm having some issue with the gate switching for the converter. Currently I'm testing the buck converter with a ...
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1answer
42 views

Capacitor Charging Voltages

I am trying to create a capacitor bank and don't know what voltage to put through. Do i add the voltage of all the capacitors up and apply that or just provide the voltage for one. e.g. If I have 10 ...
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1answer
76 views

Self powering torch - boost converter calculation

I was implementing the TPS61200 Voltage Boost Converter from Texas Instruments in my circuit to boost the voltage output from some Peltier tiles to then power a supercapacitor which would then power ...
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2answers
487 views

ZVS driver charging capacitor bank

I built this ZVS driver to make some big high voltage sparks a while ago. It worked off three voltages 24V, 50V, and 80V and had no issues. The only part of it that got really hot were the 1kohm 3W ...
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92 views

Suitable Capacitor

I am wondering what voltage rating I need for the capacitor in the attached circuit. Its basically the front end of a Tesla coil. The voltage source is a neon sign transformer 3kV open circuit at up ...
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3answers
2k views

Discharging one side of a capacitor?

What I'm asking about is if it's possible to discharge one side of a capacitor. I've found a question about that, but I also found the answers to be a little unclear or questionable. I imagine that ...
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1answer
2k views

Creating a timer in an RC circuit

In the book "Electronics For Dummies" there is a paragraph called "Creating a timer". If you’ve got a buzzer that requires a voltage of 6 volts in order to sound off, and you’re using a 9-volt ...
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1answer
70 views

24vdc current boost?

I have a access control system that applies 24vdc to a solenoid to unlock a door. The power supply is 24vdc 16a inrush, 1a constant. Due to the wire size and distance it doesn't always pull it ...
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1answer
2k views

Simple Capacitor charging and discharging question

Below is a circuit consisting of a capacitor, voltage supply and resistors. There is a switch that lets the capacitor charge and discharge. I have also uploaded the given answers below; I understand ...
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1answer
348 views

Op-amp bias issue to to charging of DC blocking capacitor

We're using the above circuit to drive a sinusoid with constant current into a custom sensor which is best modeled as a series capacitance & resistance (~100ohm, 1uF). The op-amp is single supply, ...
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1answer
271 views

Does this capacitor discharge? SCR and capacitor doubts

I'm having some doubts about this circuit and about capacitors charge/discharge in general SCR CIRCUIT; Igt= 100MicroAmps;Vgt = 0.7V Ok I have like 5 questions 1) Is flowing current through R2 and ...
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3answers
612 views

Does resistance affect a capacitor charging from another capacitor?

Consider two capacitors connected to each other, where one is charged (5.0V) and the other has no charge stored: When they are connected, current flows to even out the charge and the resulting ...
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135 views

Capacitor not fully charging

There is a problem with this circuit. The original document specified 3V for power supply. However, the capacitor 13 is only charges to around 0.8v and then stops when I used 3V and it doesn't trigger ...
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2answers
2k views

Capacitor bank design considerations for coil gun?

I am designing a coil gun using a schematic that specifies a capacitor bank of 10 1500uF capacitors in a 2x5 arrangement to provide an effective 600uF at 1000V. I am wondering why this configuration ...
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3answers
422 views

Problem with LT3750 charging

I'm trying to build a flyback circuit to charge a 1uF cap to ~300, but am having a lot of issues. I'm just following the data sheet diagram for a 300V 3A charger (see pic below). I've never been ...
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2answers
432 views

Trouble understanding charging capacitor on bridge rectifier

simulate this circuit – Schematic created using CircuitLab Boylestad's book says that with the diodes conducting the effect of the resistor is "removed" so the \$RC\$ constant is so small that ...
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0answers
1k views

Super capacitors high current charging and discharging

simulate this circuit – Schematic created using CircuitLab simulate this circuit I've been playing around with the idea of using super capacitors as the main way to start my car (basically the ...
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1answer
502 views

Large capacitors “producing more I²R heating”?

On page 35 of The art of Electronics Third Edition, when describing the disadvantages of reducing ripple by choosing large capacitors, the author writes: The very short interval of current flow ...
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1answer
106 views

Charging supercapacitor parallel with different sources

Is it possible to charge one supercapacitor with multi voltage sources in same time? All rated at near by 4V for example, 4.05, 4.1, 4.0 volts.
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Capacitor across an ideal current source

How long will the capacitor below charge? Given that both the current source and capacitor are ideal. If someone says the capacitor will be charging up to its capacity, what is the capacity of this ...
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2answers
13k views

How to define the initial charge of a capacitor in SPICE

I would like to simulate a circuit with a capaciot in LTSPICE. In the first hand, I have tried to charge the capacitors in a period of time. However, the charging current is very high and I am not ...
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2answers
76 views

understanding electrical motor and force

I am looking to drive an electrical motor to power a cart with some substantial weight. I want to power this with as simple a method as possible but want to maximise the force for it. I have several ...
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1answer
1k views

Charging 250 volt capacitors without flash camera circuit

I'm building a coil-gun in my high school engineering class and am having a little trouble charging the 5 250-volt, 1000 microfarad capacitors. Would it be possible to connect the wall to a voltage ...
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5answers
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What does 'capacitor jumping up and down' mean and what work does it do?

While studying about capacitors, I came across with an explanation talking about "jumping up and down when a capacitor separating two stages". I understood from several articles here that capacitors ...
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2answers
202 views

RC Circuit Charging and dischargin

I have been studying about time response of RC circuits. I have analyzed the below circuit. The input signal is a pulse signal of width 1.5 sec and period 3 sec. Alternating between 0 V and 5 V. So ...