# Questions tagged [capacitor]

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

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### Capacitor with conductive dielectric material [closed]

I have capacitor. I fill it with a material that is both dielectric and conductive. I need to write a equation to the potential in the capacitor and find the magnetic and electric field also I know ...
106 views

### How is the reactance of a capacitor formulated?

Question: Understanding the Reactance of a Capacitor Hi everyone, I'm having trouble formulating the reactance in a capacitor and would appreciate some help. Here's what I understand so far: We have ...
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### What are the functions of these capacitors connected to the output of a efuse?

I am a beginner in electronics, and I am studying a LiPo charger circuit: https://www.elektor.com/products/diy-lipo-supercharger-kit-v2-by-greatscott This is the full schematic: https://s3.eu-central-...
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### Quasi-polarity behavior of silicon capacitor that then reverses when put in use?

What could cause a silicon capacitor to start behaving like a quasi-polar capacitor? A filter involves two 100pF SMD silicon capacitors(600S101FT250T). Two such filters (for two channels) are ...
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### capacitive filtering of power line transients without power loss

I've been researching so-called "surge capacitors", which are claimed to augment surge protection devices (SPDs). The claim is that SPDs usually have at least a 5-10 ns response time, and ...
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### Are variable capacitors compatible with breadboards still available?

Variable capacitors are used less, since the preference is for digital adjustment. And through hole parts are used for less, since the preference is for SMD. Finally, many variable capacitors have ...
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1 vote
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### Unable to use a MOSFET to connect two capacitors in series

I am trying to design a circuit such that I can connect two capacitors in series by applying a gate voltage to a N-type (specifically IRF530N) MOSFET. I am getting results I do not understand. When I ...
362 views

### What type of cap would you use to block DC on a microphone-level audio line (unbalanced)?

I need to block a DC voltage on a microphone line, and a bit of research shows that MLCC is a bad idea because they can mechanically ring from vibration. Question: What type(s) of capacitor could be ...
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### Why are there capacitors in series in this AC/DC converter?

In a circuit with an AC/DC converter that supplies 12V and then only 11.4V because of a diode (D16), I have found capacitors in series (C33 and C38, each 100µF 35V.) That makes no sense to me since ...
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### MOSCAP retention time

I am trying to understand how MOSCAPs behave to know how to use them. I generated the figure below by connecting an NMOS in a MOSCAP configuration (source, drain, and body shorted), sweeping the gate ...
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### Solid polymer electrolytic capacitor storage reliability

I am specifying a solid polymer capacitor (Panasonic 80SXV47M) in a power supply application required for a long service life. Does this component degrade when stored powered off for long periods of ...
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### Confusion in deciding a voltage regulator's input output capacitor types

As a part of a PCB, I want to use this AMS1117-3.3 voltage regulator with 22uF input and output capacitors as follows: As for the exact part for the capacitors, I was planning to use this X7R ...
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### Do I need an input capacitor for a switching voltage regulator, if I already have electrolytic capacitors?

Assume that you're converting 24VAC to 24VDC (which becomes about 32 in reality). Then you want to covert the 24VDC to 7.5V by using a switching voltage regulator. You're already using 220 uF caps in ...
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### How do I analyze an emitter follower with a capacitive load?

How do I analyze an emitter follower with a capacitor load? At 7 MHz, a 1 nF capacitor has impedance of 22 Ω. A simple emitter follower with a 22 Ω Re is easy to analyze: However, replace that ...
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### how does ESR change as dielectric barrier increases?

Suppose I have a capacitor with a certain ESR, capacitance, and voltage. Then I double with width of the barrier between the two plates. The voltage will double, the capacitance will halve. What ...
56 views

### Capacitor ratings [closed]

If I have a 220V pool pump start capacitor rated 124-148 mf , how precise is that range? I am reading 152 mf, is that acceptable or id the capacitor bad?
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### Understanding taser circuit with MOSFET and push pull transformer

I'm trying to understand the circuit pictured. It's a circuit for a stun gun. I understand the function of the first capacitor at the front, but I'm having difficulty understanding how the push pull ...
1 vote
50 views

### Potentiometer for Kitchen Fan

I'm exploring the possibility of building a potentiometer for my rangehood fan. The manufacturer (FanTech) of the fan actually sells one (EC-10VHL) but I'm having a hard time trying to find a ...
1 vote
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I am having difficulty connecting the ST-LINK/V2 to my microcontroller. An error appears in the ST-LINK utility. I have already verified all the connections, including the decoupling capacitor, all ...
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### Can I get the internal resistance of a capacitor from the voltage, capacity, and construction type?

I have a model of a system and I'm trying to use gradient decent to find a locally optimal solution. One of the variables is the voltage of the capacitor. I think I'll be using a film capacitor, ...
1 vote
270 views

### Solving complex opamp circuits

I'm having some troubles understanding how to solve complex circuits with opamps like the following: During my lab course (I'm a physics major) the professor showed us the solution of very simple ...
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### Toggle switch from button and capacitor

In my head I see it something like this: What it must to do? When I push button first, capacitor will charge and LED will emit(B->C in transistor). Before capacitor will be discharged and while ...
29 views

### Current Drawn from Bulk Capacitor at LED-Strip Output

I want to design a power supply (buck converter) which converts 9 V to 5 V and supplies it to the LED strip. The LED strip is a basic 1 meter long 70 LEDs/meter WS2812B strip. In my project, I want to ...
49 views

### Embedded device with Hardware issues consisting atmega 328p, RFM96 and ADXL345

I have a device that works on 3V battery (2 D size cells) now I want to debug it so that all the devices work correctly. My device consist of atmega 328p, running on 08 MHz Crystal which gets readings ...
1 vote
183 views

### What is the connector name for this 820 μF 450 V Nichicon capacitor

I am trying to find a replacement for this capacitor taken from a Haier aircon unit fan motor circuit. The combination of specifications (μF, volts, size) are not currently listed on the Nichicon ...
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### Is putting capacitors in both ESP32 and HX711 overkill in this circuit?

I was getting erratic readings from my HX711, which was receiving power supply from my ESP32. I figured it was catching noise and power fluctuations from my ESP32. So I added a 0.1 μF capacitor and a ...
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634 views

### Do capacitor packages make a difference in MLCCs?

I have a circuit which has an RC dependent timer. I got two types of ceramic capacitors, both of them have literally the same value, but different voltage ratings: 1206  4.7 μF, 25 V capacitor 0805 ...
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### Is a smoothing capacitor only useful when the trace has impedance

Under conditions where maybe a capacitor is used maybe when perhaps there's a high impedance power supply and the source would cause current surges, maybe a subwoofer to a car battery that can't deal ...
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### DC bias vs AC voltage change rate on MLCC capacitors

I'm looking at this 10uF X5R ceramic MLCC capacitor. I know that ceramic capacitors which aren't C0G have an significant variation of their value depending on voltage, temperature, aging, and ...
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### A scheme to control a number of ceiling light bulbs being on with a single switch [migrated]

I have a ceiling light with two bulbs and only two wires (live and neithral) arriving to it (220-250v AC) and a SPST switch. I want to connect one bulb directly to those wires and I want the other ...
1 vote
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### Connecting the LC circuit to dc voltage source without transient

Let's say I have following circuit where the transistors are controlled via a software in the microcontroller. I have been looking for a control algorithm how to achieve a state when both of the ...
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1k views

### Freewheeling diode in a capacitor

I hope this is not too trivial a question. I know that a freewheeling diode is connected across an inductor to eliminate the sudden voltage spike that occurs across an inductive load due to ...
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### USB bank + capacitor for flash gun

I have a camera flash (Godox TT350), which typically takes 2 AA cells. These cells do not last long, so I bought some dummy cells, which are connected to a USB plug. The USB is inserted into a battery ...
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### What is the purpose of this circuit inside a solar lamp?

I'm trying to get started with electronics, just as a side quest. I found this little circuit inside a solar lamp I had. I'm trying to understand what its purpose is and why it uses its components, ...
258 views

### Using only ceramic capacitors on an input of an SMPS - unclear advice from manufacturer

I was reading through the datasheet of a boost converter, TPS61023 from TI. In the "Input Capacitor Selection section", they give the following advice: Notably, TI advises against using ...
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### Where does capacitor matrix come from in meyer model?

The following is from FIRST ORDER QUASI STATIC MOSFET CHANNEL CAPACITANCE MODEL. The total gate charge $Q_g$ is a function of the terminal voltage under steady-state conditions. The gate ...
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### RC series analysis with H parameters model

I'm writing this just to be sure I understood well the process of analysing a circuit with the $H$ parameters model. In this case, it is a very simple example of application; the circuit I'm ...
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### NCP1117 (3.3V LDO) with ceramic and aluminum electrolytic capacitors

For my ESP32 project I want to use a NCP1117 3.3V LDO and soon the question came, which capacitors are suitable if the LDO is driven either by USB or a 5V power supply while the cable length is about ...
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### 555 IC - Role of Resistor in Capacitor Discharge (Astable mode)

I can't grasp the role of resistor Ra in this circuit. I know that when the output from the SR latch is low, the transistor doesn't allow the capacitor to discharge. And when the output is high, ...
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### Cyclic Voltammetry for a Capacitor - Positive Current, Potential is decreasing?

In the boxed red region, why is the potential decreasing when the current is still positive? To my understanding, when the current is still positive (i.e. not changing direction), the capacitor will ...
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### Why Capacitor can't behave like smoothing DC effect in AC motor Phase shift application?

Capacitors in AC-to-DC power supply will work as smoothing after Diodes, which means it is charging on Positive peek, and will store charge on decrement of Peek, so it is providing smoothing DC Output....
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### How to bias an input AC signal for active high-pass filter?

I have been trying to design a 2-way active crossover, with low-pass and high-pass channels. So far I got the desired frequency response but the transient response is not up to mark. Here is the ...
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### Can I use a polyester capacitor instead of a film (A/C PCB)

My A/C indoor PCB blower runs about 40% slower than from new. I have replaced all capacitors, blower motor. BUT yesterday I noticed I didn't check for one specific capacitor. It says: 0.22 μF (220 nF) ...
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### Wiring Portable AC to Run at Max

I'd like to wire this portable AC to always run at max (compressor on and fan at max speed). I'm using it for a project where the temperature is going to be controlled by controlling the power to to ...
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### Designing a 4 H-bridge PCB board using a DRV8871

I want to make a 4 H-bridge PCB that consists of 4 DRV8871. I have seen the schematic that Adafruit has posted for their design and looks suitable for my case. So my idea was to repeat their module 4 ...
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### Are $v_{C}$ and $v_{L}$ in phase in an LC oscillator?

Looking at these figures, I can't help but to conclude that $v_{C}$ and $v_{L}$ are in phase! Why? Well, because $v_{C}=q/c$ I know this is wrong but why? Reference: https://shorturl.at/30NEu
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### Capacitor Insulation Questions

I wanted to create a high voltage parallel plate capacitor with a positive voltage connected to its positive plate and ground connected to its negative plate. Can I get away with a thin sheet of ...
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### Why does this arc die in the center?

I discharged a capacitor across the primary of an old microwave oven transformer. As expected, the transformer made a huge spark. I am generating the spark by charging a capacitor with a bug zapper to ...
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Consider the following RC network: DC voltage source $V_{s}$, in series with resistor $R_1$, in series with capacitor $C$, which has parallel to it another resitor $R_2$. For this network: \\$...