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# Questions tagged [capacitor-charging]

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### Calculating capacitor charging and discharge time using LM311 as Schmitt trigger astable multivibrator

I need a little help solving some electronics problem. I need to calculate the charging and discharging time of a capacitor in the following Schmitt trigger astable circuit using LM311 I found. If I ...
• 21
1 vote
3 answers
135 views

### Transient analysis of RC DC circuit

The task is to find the current that flows through capacitor C. I tried to analyse the circuit using mesh analysis but failed. I need to find the current through C during switching (t=0) and steady-...
0 votes
1 answer
58 views

### Wide input voltage capacitor charging control

I'm working on a project in which we are using a bank of inexpensive 100 μF caps (up to 20 of them) to keep a microcontroller powered up long enough to do housekeeping for shutdown when the main power ...
0 votes
2 answers
174 views

### Charging a capacitor through a diode

I am a student who is trying understand some things. I read in a book that a capacitor can charge up to battery voltage when connecting in series with a resistor and battery like this: Can it charge ...
• 29
2 votes
1 answer
140 views

### Can someone explain the purpose of this transistor?

I have a schematic for a THT design. All diodes are rated for 1A (1N4004). The resistors are 1/4W and the transistor is a BD679 NPN darlington transistor (I am aware that I used a wrong symbol). This ...
• 616
0 votes
1 answer
96 views

### Find suitable charging voltage for capacitor based on energy and time required for discharging

We need to calculate the charging voltage required to dissipate a certain amount of energy via R-Load. The problem will be as follows: If we need to dissipate 400 J through the R-Load in a time period ...
1 vote
1 answer
89 views

### Spice convergence troubles on this soft-start relay circuit simulation

I'm experimenting with a soft-start relay simulation. The relay is triggered when the capacitor bank C2 is charged a certain amount shorting R4. I then simulate loading V_out with a sequence of ...
• 1,341
0 votes
0 answers
62 views

### 10 - 230 V DC voltage detector using STM32

I am working on a stud welder device capable of weld M3 ~ M8 bolts and the principle is to charge the caps in the range of 10 - 230 V DC, So we have a 220 to 160 V AC step down transformer and after ...
0 votes
0 answers
69 views

### Using an analog switch to charge/discharge a series of capacitors

My circuit requirement is very low power consumption to allow/disallow voltage (V1 which is variable 0-5 V) to go through some capacitors (cap1 and cap2) by controlling analog switches (DG2535EDQ) ...
• 25
5 votes
1 answer
1k views

### LTspice capacitor bug?

I know that capacitor slows the rise of voltage, but why is this not happening in the LTspice simulation? I got the input voltage at the output instantly.
• 107
0 votes
1 answer
86 views

### How to spec a power supply for capacitor charging given the simulation and large requirements?

I am using the LT3751 as a capacitor charger for a large capacitor (30mF) and am trying to get an idea of the kind of power supply I would require in order to come close to the simulation charge time. ...
1 vote
2 answers
202 views

### RC differentiator behavior

I'm reading AoE, there is a figure (p.26) for RC differentiator output and input voltages for step 5V input voltage with different slew rates ($dV_{in}/dt$). (It's time domain part. Only the rising ...
• 13
-1 votes
1 answer
46 views

### Subtleties with LTSpice's Arbitrary Sources

Here's my setup: I'm trying to emulate the circuit to the right with the one on the left. That is, the one on the right is a pre-charged capacitor (node3) being discharged to its capacitor pair via a ...
• 279
0 votes
2 answers
617 views

### Series capacitor not blocking DC voltage

In my understanding a series capacitor (with some resistance) works as a DC block, essentially forming a high-pass filter, blocking DC. Under this assumption, a unipolar square wave of amplitude V ...
• 587
5 votes
4 answers
956 views

### Charging supercapacitors with reversed polarity

I bought six supercapacitors and connected them in series to get a total voltage of 16.2 VDC. The product's Mouser No is: 723-BCAP0450P270S18, Mfr. No is: BCAP0450 P270 S18, the datasheet can be found ...
• 85
0 votes
1 answer
214 views

### How to avoid battery spark when connecting it to a DC-DC-converter [duplicate]

I'm connecting a 40 V battery to a DC-DC converter that can step down a voltage from 40 V to 8 V. When I connect the terminals the battery gives off a spark. I've browsed some sites which say that ...
• 141
4 votes
1 answer
209 views

### Capacitor current in parallel network with ESR and parallel resistance

So this might be a very simple question and I've got a knot in my brain but I've been at this for days and don't see how I could solve this problem. I'm trying to find the solution for both ucA, ucB(t)...
7 votes
3 answers
2k views

### LTSpice: Why are my capacitors half charged at simulation start?

This is my first time using LTSpice, and I am trying to simulate what should be a very simple RC circuit ladder. I've gone ahead and set the initial state of each capacitor to zero using the .IC ...
1 vote
2 answers
112 views

### Output voltage of capacitor discharged in other capacitor?

Considering this circuit. How can I compute the maximum voltage across the resistor ? In this example, the capacitor on the left is initialy charged with 10 V. The second capacitor (on the right) is ...
• 157
1 vote
2 answers
531 views

### Why is my capacitors' leakage current much higher than it should be?

I have a capacitor bank consisting of five 3.3 mF electrolytic capacitors. (Itelcond 400 V 3300µF datasheet here.) The five capacitors are connected in parallel and there's a charging circuit with a ...
• 341
0 votes
3 answers
297 views

### Does the 555 timer 50% duty cycle capacitor discharge not affect the output voltage?

I'm new to the 555 timer and I'm trying to understand the configuration shown in the image below. The tutorial mentions that the capacitor C1 now charges and discharges through the resistor R2. The ...
• 29
-2 votes
1 answer
76 views

### Precharging my capacitor manually - looking for feedback [duplicate]

This is my plan, to pre-charge my capacitor of my electric vehicle manually, to prevent sparks occuring when connecting my heavy duty battery. The cables can easily handle 600A as well. Im asking here ...
0 votes
1 answer
268 views

### Charging capacitor trips breaker

I am designing a circuit to drive a DC motor from rectified mains voltage. For that, I have added a 1200uF capacitor. My problem is that this circuit is supposed to work on a user's home power plug, ...
0 votes
3 answers
154 views

### Are my capacitors working properly or not?

I've bought some capacitors because I needed to generate a current pulse into a coil. The idea was to charge a capacitor separately and then connect it to the coil to have a strong and brief magnetic ...
• 3
1 vote
0 answers
68 views

### Component protection and charge optimisation for Solar + Supercapacitors

What are the best protective practices for solar cells and supercapacitors when they are used for small outdoor projects? Moreover, are there any way of widening the useable voltage output range of a ...
• 506
0 votes
4 answers
1k views

### Short-circuit current through disconnected capacitor

I have a large capacitor made of two smaller 200V rated 560uF capacitors. If I charge this capacitor to 30V with 4.5A from a bench power supply and disconnect it after around 7 seconds, how do I ...
0 votes
1 answer
181 views

### Briefly switching a coil

We are going to build a telegraph which can communicate to an other telegraph. One of our communication systems exists out of a bell. The idea is that the sender can press a button and the receiver ...
• 616
0 votes
0 answers
40 views

### Choosing the right capacitors for multiple sub-loads in the system when the main power source is unreliable

Hello there, I'm working on a system that has unreliable power source like solar cell (that why I put a switch in the schematic to indicates that).The general idea of the system is breaking out the ...
• 25
3 votes
3 answers
2k views

### RC circuit with a constant current source

I am trying to simulate a series RC circuit excited with a constant DC current source in LTSPICE. The expectation is that it should linearly charge the capacitor with a constant current flowing ...
0 votes
0 answers
516 views

### Parallel connection of DC DC Converters with different output to charge the battery

Generally, in connecting power supplies parallel one can follow current control or droop control rather than voltage control to regulate the output of a dc dc converter. If the output of both the ...
2 votes
1 answer
114 views

### 555 timer capacitor charging order

I have a question about the standard 555 circuit below. I understand to some degree the "insides" of the timer. In particular, I understand the role the comparators play and I am fairly ...
• 123
0 votes
3 answers
67 views

### How can this circuit be best described?

Here, the green waveform is the input waveform(V1) and the blue waveform is the potential drop across Vc1 and Vc2. To me it seems like a peak detector getting clamped, but then the first half cycle ...
-2 votes
1 answer
90 views

### What is this circuit with increasing voltage of full rectified wave?

{ The first image is original circuit.} { The second image is the output across RL resistor with ac source amplitude voltage 5V. } {Simulated circuit with output measured between A and B nodes.} To me ...
0 votes
1 answer
299 views

### Why does AC charge the capacitor?

I know that capacitors charge and discharge at the same rate. As the total the there will be no charge or no energy stored. When I connect a fan capacitor to the AC home source for few seconds and I ...
0 votes
0 answers
79 views

### Since current through capacitor (between the plates) is displacement current, what is the current flowing to the leads of a capacitor called?

Since there is no conduction current through the capacitor, what is the current that flows between the battery and the leads of the capacitor while the plates are charging (or discharging) to their ...
• 639
0 votes
2 answers
155 views

### Bezier curves in hardware? (X-Y-mode on oscilloscope)

As I am exploring how to use an oscilloscope as a raster display in a question yesterday, and building the circuit, I am finding that with about the same (even less) components I could build a vector ...
• 1,541
0 votes
1 answer
174 views

### Parallel Diode in RC charging circuit

When button is pushed , active low RES pin is activated till Vc reaches 2.5 Volts. I have two questions here 1. What is the role of Diode which is connected reversed biased? 2. Which loop capacitor ...
0 votes
4 answers
1k views

### Charge a capacitor with negative pulse [closed]

What will happen if I apply a negative pulse to the capacitor? Is the capacitor voltage increase positive or negative? The pulse which is shown in the below picture is the output voltage pulse from ...
2 votes
1 answer
682 views

### Power ESP8266-12e for 0.5 seconds after power cut

I have an ESP8266-12e (ESP1) that is connected to Blynk with a momentary button. When the button is activated it makes pin D5 HIGH which goes through a transistor and powers the set side of a latching ...
• 215
2 votes
1 answer
335 views

### How to model/get a capacitor to discharge slowly at first?

Typically, a capacitor discharges fast at first, and then discharging slows down until it approaches 0. Is there a way to slow the initial phase of discharging, so the capacitor does not immediately ...
2 votes
2 answers
574 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 ...
• 17.8k
0 votes
4 answers
54 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 ...
2 votes
3 answers
227 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: ...
0 votes
1 answer
334 views

### Multisim does not simulate the capacitor charge correctly

If I simulate this circuit in Multisim everything works fine, but in reality the LEDs burn, if I put a 1k resistor in series with the capacitor the LEDs no longer burn I think the LEDs are burned by ...
• 227
9 votes
2 answers
2k views

### A question about relaxation oscillator

I was studying the function of this simple relaxation oscillator based on a single transistor, 2N4401. The schematic looks like this: From ...
2 votes
3 answers
847 views

### What happens when the voltage applied to fully charged capacitor becomes lower than initial voltage?

I have 24 volt capacitor and I charged it fully using 24 volt power supply. What happens if the power supply voltage becomes 20 volt which is connected to the capacitor that is fully charged at 24 ...
• 17
1 vote
1 answer
243 views

### Using a compartator to make an LED light up. How do I make the LED light up?

This is my circuit that lights up an LED for less than 4 seconds of volts using 4V. How do I make the LED light up? I thought the output of the comparator was the comparators supply voltage, and that ...
0 votes
1 answer
54 views

### Am I calculating the V(t) and I(t) of all of the elements in this RC circuit incorrectly? (two resitors and 1 cap connected to 10V DC)

Am I doing something wrong calculating the current and voltages at time t for the RC circuit? I put these equations on google sheets and the voltage across all of the elements passes 10V between 4 and ...
0 votes
1 answer
232 views

### Transistor activation / deactivation voltage in

The capacitor was allowed to discharge completely when the transistor was activated with the 3.4 V. The capacitor is allowed to charge again when the conduction from the 5 V line through the ...
1 vote
1 answer
134 views

### Charging three individual capacitors with one AC power source

I'm trying to charge three capacitors by using my country's net voltage of 230V (60Hz) AC. The net voltage is connected to a diode bridge, which thereby results in approximately 325V DC. Each ...