Questions tagged [capacitor]

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

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2 answers
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What happens if you use L or C components in RF filters above their resonant frequency?

We have been optimizing filters (BP, HP, LP) by dropping a set of .s2p files into Microwave Office and letting the optimizer choose what works "best", but I started to wonder if that was a ...
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7 votes
3 answers
325 views

Why are electrolytic capacitors still in production?

What are the advantages of using electrolytic capacitors? I know in the past electrolytic capacitors would have more capacitance, but with MLCCs they seem completely obsolete. The MLCCs also can have ...
0 votes
1 answer
61 views

How to find phase shift from oscilloscope?

In university we are tasked to input a 10Vpp 50Hz signal, in a series RLC circuit. I’m having trouble understanding the difference between a positive and negative edge phase shifts on Agilent ...
2 votes
2 answers
1k views

Why doesn't the capacitor fill to the maximum?

I am comparing a simulation and a real experiment I did in which my capacitor didn't fill all the way. The capacitor I used is 10 μF with a 1 kΩ resistor with a 12 V source. I have both graphs: This ...
0 votes
0 answers
17 views

S parameter model of the capacitor

For same capacitor, there is no s-parameter model, so can we use the model from other manufacturer of the same spec. Eg: Caps with model - C0603C104K5RACTU - KEMET - Cap, Cer-X7R, 0.1uF, 50V, 10%, ...
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4 votes
1 answer
104 views

Any thoughts on a supercapacitor battery project?

Just some insight: I am fifteen and have been researching capacitors for a while now. I have come up with the idea of building a supercapacitor power supply unit solely to power some small electronics ...
0 votes
1 answer
33 views

Maximum capacitance on 12 V ATX PSU

I'm designing a fan controller for a PC. It will be controlling 6 fans. I want to start initially with 100 µF tantalum capacitor for each fan. Can 600 µF capacitance on the 12 V line (4-pin, 5.08 mm ...
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0 votes
0 answers
66 views

Ultra-fast load switch

I have a question that I am assuming has a very easy answer (hopefully). I am trying to turn on and off the power to a pcb really fast, on the order of 1us. My problem is that my board has some bypass ...
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0 votes
1 answer
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Converting my PC's On/Off Status LED to a Fading LED

Right now the output of the LED blinks on and off when in standby. This is pretty annoying. I was looking for a way to turn this circuit into a fading LED instead. The simplest solution possible I ...
1 vote
2 answers
82 views

Powering ESP32 and two MG90S using supercapacitor

I'm working on a drone-dart project. Dart is controlled by an ESP32CAM and two MG90S servo motors. It is raised to the sky by a drone and then released. The dart falls while attempting to aim itself ...
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1 vote
1 answer
57 views

P-MOS control and capactive load

I am trying to drive an high capacitive load with a P-Mosfet. I added a PTC to limit the current, but it doesn't seen to be working. The mosfet is often killed. Can anybody help and provide a 'simple' ...
1 vote
0 answers
60 views

Charging equation of a capacitor in circuit with two capacitors

Following the answers received to my previous question, I obtained many ideas and I realized that what I was really looking for was something else and needed a new post: I would like to analyze the ...
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12 votes
6 answers
986 views

Ripple voltage filtering capacitor

I'm an self-taught high schooler who's trying to understand how filtering capacitors work. I've searched and read multiple websites trying to understand how filtering works. At the point where I am, I'...
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7 votes
5 answers
912 views

Why doesn't the bypass capacitor cause phase shift in this oscillator circuit?

I am trying to understand oscillator basics. I thought I already understood how a capacitor works, but I still get confused about it. This circuit is an RC phase shift oscillator. I understand that we ...
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0 votes
0 answers
45 views

Capacitance of the capacitor in a coilgun

A coilgun's electromagnetic field strenght mainly depends on the ampere-turns. If we have two capacitors: 1000 μF, 390 V 470 μF, 390 V Which will be stronger and why? Does the capacitance really ...
7 votes
5 answers
993 views

Converting 24 VAC to 5 VDC with small output current

I have a transformer which outputs 0.33 A at 24 VAC. I would like to rectify this down to 5 VDC and minimal current, 50 mA being the maximum. I came across the following schematic which seems to be ...
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3 votes
2 answers
1k views

Purpose of capacitor connected across AC input in a smart bulb?

I recently had an IKEA smart bulb (TRÅDFRI, E27) go bang, but it continued working. After disassembling it, I discovered that only a single capacitor had failed. The capacitor is connected directly ...
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0 answers
26 views

Calculating required capacitance for ESC?

I'm working on an ESC design, but I'm not sure what capacitance is needed on the output terminals to smoothen out the voltage sags. Any ideas on how to calculate this?
0 votes
1 answer
39 views

Is this method of proving energy is conserved in an LC oscillator correct?

Assuming no energy loss due to heat or EM waves $$U=\frac{Q^2}{2C} +\frac{LI^2}{2}$$ differentiating both sides with respect to time, $$\frac{dU}{dt}=\frac{QdQ}{Cdt}+IL\frac{dI}{dT}$$ but we know that ...
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0 answers
58 views

Older induction motor needs spin to start it

Tl:DR Motor requires hand spin to start. No starter switch. EDIT Further information: So I tried removing the capacitor completely. Started it. Starts very slowly, with much grumbling. Give it a ...
2 votes
1 answer
44 views

Efuses, inrush and output drooping

Here's a simplified efuse diagram: Here is the efuse configurations in my circuit: The load is not present on this pcba. There is a 100mm long cable connecting this board to the load which is a ...
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1 vote
1 answer
41 views

Pure sinewave cascaded H bridge multilevel inverter

What is the function of the capacitor C1 in this inverter circuit?
2 votes
1 answer
62 views

Triangular wave response of RC circuit

I am trying to intuitively understand the response of the RC circuit for a triangular input. My understanding is as follows: Let the ramp be mt.u(t) Initially, the voltage drops mainly across the ...
2 votes
1 answer
48 views

Choosing capacitors for QI charger

I plan on using the TI BQ51051B as a QI reciever and Li-po charger. I plan to use the TDK WR121210-27M8-ID as the receiving coil, and the TDK WT151512-22F2-ID as the transmitting coil. I am having ...
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2 votes
2 answers
93 views

How important is capacitor life span? [closed]

As above. I am deciding between 3 capacitors. I need 6 capacitors arranged in 2 banks with 3 capacitors in parallel each for a V+/V- unregulated power supply for an audio amplifier. Capacitor 1: ...
4 votes
1 answer
667 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.
1 vote
2 answers
51 views

LDO maximum output capacitance

The LDO datasheet usually specifies the maximum output capacitance for stability reasons. I wonder if this capacitance is meant for the entire power plane or just the capacitor right at the output of ...
-1 votes
1 answer
65 views

How to choose the right type of capacitor?

I built an AC power supply (we called it a TENG) based on the tribo-electric principle. It can light up about a hundred 3 mm LEDs. Now I want to try supplying the power from my TENG to an LCD ...
4 votes
1 answer
145 views

Power loss in a capacitor vs inductor

Is there are a general rule of thumb if one of these stores energy more efficiently than the other? When properties are approximateily comparable, are energy losses bigger with a coil or with a ...
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0 votes
1 answer
59 views

Capacitor to earth in floating power supplies

I'm looking at using two separate, floating supplies in a 20W power amplifier design to generate +24V, 0V, and -24V low-impedance rails. Some research suggests this is doable, and seems much less ...
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2 votes
2 answers
106 views

MOSFET gate failure caused by unknown reason

I have the below circuit (link to simulation). It represents the low-voltage interlock and high-voltage precharge & discharge circuit for my Formula SAE team's EV car. While most other FSAE teams ...
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2 votes
4 answers
383 views

Why does capacitance affect the charging time of a capacitor?

I'm trying to understand the relationship between the capacitance with the voltage output of this circuit. If the capacitance is greater, why does it take more time to charge the plates of the ...
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4 votes
4 answers
201 views

Time constant of a high-order RC circuit

I have an unknown system that can be modelled as a high-order RC circuit: I performed the impedance spectroscopy measurement of it and fitted the equivalent components. Now I should calculate the ...
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1 vote
0 answers
110 views

What is the purpose of these capacitors in series with LEDs?

I am planning on building a device that sends IR light into a head at a specific intensity and detects the intensity that is measured by a photo diode. I know that ...
0 votes
1 answer
44 views

Is there a relationship between capacitor ripple current and the transformer secondary current output rating?

As an example: I was looking at a 10000 μF, 50 V capacitor with a ripple current rating of around 5 A at 20-120 Hz. My transformer secondary is rated for 24 VAC, 20 A.
2 votes
1 answer
41 views

Maximum allowable AC voltage for film capacitors as a function of frequency

For a project that I'm working on, I would like to generate an oscillating magnetic field. In order to achieve this, I would like to create a series LC circuit with multiple film capacitors in series ...
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3 votes
3 answers
181 views

What is the cause of my resistor going up in flames? [closed]

An LED strip in my kitchen recently died, and from looking at damage to the circuit board, I figured the cause was either a resistor, a capacitor, or both. Images: Resistor damage (full size left, ...
0 votes
0 answers
27 views

Kenwood Dnx891hd rca output fuse

I have a Kenwood dnx891HD and I've had problems with it for years I finally sent it in due to protect mode and they sent me a picture and told me it was this rca output fuse on the circuit board and I ...
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1 vote
0 answers
75 views

PCB Layout DRC warning

I designed my own Layout in Kicad, but after running the DRC there are some warnings. Does anyone know what is wrong with the layout? (More info in the attached images). I thought the net describes ...
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0 votes
0 answers
78 views

12 V vehicle bulb voltage monitoring - prevent flashing LEDs (potential circuit design?)

I have a digital dash in my car (Haltech IC7) which has inputs for lights so that it can display indicators etc. on the digital dash. I've tried coding out voltage monitoring but it doesn't seem to ...
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-2 votes
3 answers
76 views

How to add a DOWN limit switch to a Harbor Freight (Pittsburgh) hoist [closed]

I am using a pittsburgh hoist to raise and lower a large curtain. The hoist has a built in limit switch to stop when it raises to a certain point. I need to add another limit switch to stop the hoist ...
0 votes
1 answer
42 views

Temperature of radial electrolytic capacitors

I have been building boost converters. My current revision is working well at about 300 W, 55 V in to 86 V out. The main problem I now face is that the output capacitor is getting quite hot. If I ...
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4 votes
1 answer
186 views

Questions regarding this power module

I'm looking at this power IC module. I assume it's a buck converter. In that case, on page 16 of the datasheet, Equation 4.1, there's this formula: Rvout = 8.2 kΩ * TRIM. If TRIM is 5, then what would ...
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0 votes
0 answers
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Electronics Lab - Not measuring voltage drop across resistor connected in series with capacitor

I'm working on an RC circuits lab for school, and it stated to connect a circuit as follows: 15VAC in series with a 470-ohm resistor and 4.7uF capacitor and measure the voltage drop across the ...
2 votes
1 answer
47 views

What is the function of the feedforward capacitor on the LM2596-ADJ?

I'm looking at the LM2596S datasheet and notice that on page 7 (figure 3) it recommends a "feedforward" capacitor for the adjustable variant. The example schematic on page 9 shows a ...
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0 votes
0 answers
40 views

How to speed up precharging of the DC link capacitor of the three-phase inverter?

Let's say I have a three-phase inverter with a DC link capacitor of substantial capacity. I would like to charge the DC link capacitor to a DC voltage. One possibility is to use a resistor which is ...
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0 votes
1 answer
77 views

How to determine saturation in DC smoothing choke with capacitor, and how to simulate in LTspice?

This question addresses some of the issues with a choke made from a microwave oven transformer for producing smooth DC from a phase-fired SCR controller, as discussed in this question. The choke ...
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2 votes
0 answers
52 views

How to measure leakage current through a capacitor in a simulation?

I am trying to design a new capacitor and then measure the leakage current through it. First, I want to find a way to measure the leakage current through a capacitor. I am using a PDK which has real ...
0 votes
2 answers
88 views

Resistor in series with capacitor or inductor

Why do we put resistors in series with capacitors or inductors in single time constant circuits? In this diagram we see a resistor connected in series with a capacitor. This could act as a low-pass ...
1 vote
1 answer
92 views

A parallel plate capacitor is insulated in a vacuum. How long will the charge hold?

I've been researching parallel plate capacitors but couldn't find many experiments on how long a sealed parallel plate capacitor could possibly hold its charge and why. To experiment, I ordered a 5 ...

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