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Questions tagged [capacitor]

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

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Modify Ring Contact Sensor in a series of wired security reed switches

After reading the instructables post on the simplisafe sensor I modified the ring sensor and tried to integrate it with my wired sensors. This is what I found: testing with a spooled wire about 20 ...
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1answer
58 views

Series connection of capacitors

I have some questions for the series connection of capacitors. It would be great if someone could help me get these. What will happen for the below cases when you have 2 capacitors in series and 2 ...
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1answer
449 views

Compact circuit with multiple PAM8403

I'm building a 6 channel circuit with the PAM8403 (Filterless 3W Class-D Stereo audio amplifier) and was wondering if I could make things more compact by using less components. Is it possible to ...
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69 views

Does (stray) capacitance depend on voltage?

While thinking about how to reduce stray capacitance on my pcb, I got triggered by the question: Should the stray capacitance depend on the voltage difference? Acccording to the equation of ...
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4answers
56 views

Point of contact with a capacitor plate & rolled design?

With a simple parallel plate design for a capacitor, does point of contact(to the external circuit) matter? I imagine any point(a - e) would yield the same feature in storing/discharging charge. ...
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1answer
61 views

Linear voltage regulator output capacitance limit

I am in doubt about selecting the value of bulk capacitors for my system. I am going to use LP5907 voltage regulator. According to the datasheet, the maximum output capacitance is 10uF. Does it mean ...
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3answers
88 views

How to convert 8-bit information containing MIDI note, to square wave signal using basic chips and components? [closed]

Using basic electronic components (capacitors, transistors, etc) and/or chips (555, 74 series, etc) how do I convert from: Input: 8-bits containing the binary representation of a MIDI number "...
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1answer
81 views

Capacitor discharge

So I came across this article on CircuitDigest where they explained the functionality of a voltage doubler designed with capacitors. The circuit shown is the following: At first capacitor C3 is ...
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1answer
105 views

Removed all ceramic SMD capacitors without markings on them from the board… what to do? [closed]

When I told a buddy that I am taking electronics courses and learning to manufacture simple homemade PCB boards, he found me a client with an interesting offer: To reverse engineer a small PIC ...
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1answer
98 views

How do select capacitor for 400A surge currents?

I have a 220nF capacitor in a series with my surge protection circuit. As can be seen from my spice simulation, the capacitor gets a surge of current passing through it under fault conditions, and ...
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57 views

A conductive ball connected to a capacitor

I am not asking for a task solution, but rather how to solve a problem. Say I have a ball of radius R, charged to a voltage of U (relative to the ground). I also have a flat capacitor with a side ...
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28 views

1V Overshoot and Undershoot on Power Rails of LTE Module

I have designed a PCB (four layer) having SIM7600I LTE Module. The Stackup is: Signal & Component Layer with Ground Pour Internal Ground Power Plane Internal ...
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37 views

Must film capacitors be derated according to the voltage applied? [duplicate]

I know electrolytic capacitors must be derated according to the applied voltage, with some losing a significant part of their nominal value at high voltages. Is it a similar case with film capacitors?...
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60 views

Circuit that averages voltage

Suppose we have an oscillating signal V(t) with V(t) >= 0. I'm looking for a circuit that averages this signal over a given time so that I can read out the average value directly using a simple ...
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36 views

LTSpice PWM Signal Showing Capacitor isn't Fully Discharged

I'd like to create a pwm signal input to mimic a real life situation of a pwm input that shows the capacitors aren't fully discharged. Please see the image below. I am currently able to create the pwm ...
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1answer
53 views

How do I calculate the voltage across a capacitor when the source is a square wave?

I have a series RC circuit with R= 2.2K Ohm and C=100 nF, and the voltage supply is a 2.5V peak square wave. And I'm not sure how to calculate the voltage across the capacitor.
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4answers
2k views

Capacitor electron flow

Well I was just wondering, a capacitor is made of 2 metallic plates separated by insulating material. During the charging of the capacitor electrons flow towards the opposite direction the battery's ...
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2answers
98 views

Are my calculations wrong for the capacitance?

In an earlier post i discussed about the effects of voltage derating on a capacitor. From here i measured the output with DC and AC applied to a highpass filter and found the cutoff frequency with the ...
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80 views

Orientation of “bipolar” capacitors on PCB

I've come across a video on a popular and well-respected electronics channel on Youtube where they say that even bipolar capacitors have a preferred orientation in a circuit that minimizes hum and ...
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32 views

Multiplexer between Capacitor and Inductor (Tank circuit)

I am trying to design an inductance and capacitance meter with multiple scales, to achieve this I thought a multiplexer can do the job, but it didn't. My question is: What is wrong in this design ...
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4answers
194 views

Aluminum electrolytic or ceramic capacitors for linear regulator input and output?

I am using this linear voltage regulator. The datasheet indicates the input and output values for the capacitance to use, 1uF and 10uF respectively. Should these capacitors be or a particular type, ...
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41 views

Calculate U(t) when capacitor C1 charges C2 via a resistor R

simulate this circuit – Schematic created using CircuitLab The switch SW1 is activated at t=10s and charge from C1 is transferred to C2. The power supply charges continuously with 1kV 1mA. How ...
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41 views

How to calculate the reactance of a capacitor with an input signal that is 2 sin waves of difference frequencies added together?

I am trying to calculate the reactance of a capacitor with an input signal that is not a single frequency. For example, x = sin(4t)+sin(5t), or a capacitor that is used in an audio circuit like the ...
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20 views

Calculate Capacitor mf for PAM8402 Amp Powered From RPi

Trying to figure out what capacitor mf I should use for a 5v PAM8402 audio amp that is powered by a Raspberry Pi. When the amp is first turned on it triggers the Pi's low voltage warning. I'm using a ...
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2answers
865 views

How to read the value of this capacitor?

I came across this capacitor in a voltage converter which was converting 9V to 5V. This capacitor was connected at the output of M7805CT (i.e. between the 5V and common terminal) in parallel to ...
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2answers
60 views

Charging capacitor to power LED with a low current source

I have a 10000uF 6.3V capacitor, and my source is generating 3.3V and 15uA of current. How long will it take to charge it enough so i can pulse a standard 5mm LED for lets say 1 second?.
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1answer
124 views

Zener diode parallel to RC circuit

In the left hand side part there is a diode in series to parallel RC network. And in the right hand side there is a zener diode in parallel with series RC network. How do these sub circuits operate? ...
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1answer
74 views

Calculate the turn-off delay of an LED in parallel with a capacitor

I am trying to create a Custom turn off delay for an LED. For this I take an Capacitor in parallel to an LED My Idea so far was: I have the General Equation for an Capacitor. And the General ...
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1answer
40 views

Clamper circuit, how to apply kirchhoff when the diode is turned around?

in this clamper circuit it's easy for me to determine the output waveform: This is how I do it: In the positive half cycle, the diode is forward biased with a drop of 0.7 V, so the positive half ...
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3answers
149 views

Why does a capacitor charge faster when there is a diode connected?

In an series RC circuit why does a capacitor charge faster when there is a diode connected in parallel with the resistor? I tested on an oscilloscope, using a square signal and this is what I got. ...
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2answers
56 views

What capacitors are proper to use for input of AC DC converter?

I am trying to build an 120 AC to 15 DC @ 200 mA converter using a Power Integrations LNK3206P. Using the full bridge rectifier setup on Table 10 from application note AN-70, Cin1 and Cin2 should each ...
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3answers
78 views

About dynamic equations and the transfer function for the circuit

/ Attempt Follow my setup $$v_1=u_2$$ $$i_1=C\frac{du_2}{dt},v_2=L\frac{di_2}{dt},i_2=\frac{u_2-v2}{R_2},i=\frac{u1-u_2}{R_1}$$ According to KCL: \$i=i_1+i_2\$ Let \$s=\frac{d}{dt}\$ Get \$R_2(...
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1answer
40 views

Powering a microcontroller with a small solar cell and a capacitor

I'd like to power a microcontroller with a small solar cell. The idea is for the solar cell to charge a capacitor, and when a given voltage is reached, do some clever things to discharge the capacitor ...
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3answers
83 views

How to replace relay with N-Channel Mosfet

I have this simple circuit which uses a relay to charge and discharge a capacitor. Now instead of a mechanical switch, I want to use an electronic switch such as a N-Channel Mosfet. How can I ...
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63 views

Why wierd capacitance values [duplicate]

Why are capacitors available with values like 378 µfarad and 0.22 farad which have prime numbers like 11 and 7 in factorization instead of values like 375 µfarad and 0.2 and 0.25 farad ...
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41 views

How does a electropermanent magnet work?

I’m trying to wrap my head around electropermanent magnetism. I read this wonderful PhD Thesis by Ara Knaian as well as details the history of this concept as well as Kyle Gilpin, Ara Knaian, and ...
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109 views

On purpose shorted capacitor in schematic

I've come across this schematic from an RF device where I've spotted some weird configuration of capacitors. There are, all around the schematic, some shorted capacitors which I can't figure out what ...
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1answer
38 views

Create a polar cap with a diode?

I'm trying to order components, so I can make a board following this circuit. My problem is, I cannot find any 0.1uf capacitors, that are rated at 275VAC. The highest voltage I can find, in stock, is ...
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2answers
2k views

Replacing tantalum capacitor with ceramic capacitor for Op Amps

I am trying to build non-inverting amplifier with certain op amp; THS3491 The datasheet is linked below. http://www.ti.com/lit/ds/symlink/ths3491.pdf On page 25, there is non-inverting ...
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46 views

STM32F0 Capacitive Touch Not Detecting

I am trying to implement a simple capacitive touch sensor using the STM32F0's TSC peripheral. I currently have the following setup. (PA1 and PA2 are switched in the schematic, accidentally) simulate ...
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2answers
88 views

Is it good idea to charge a battery from a starter-capacitor of an AC generator?

Some friends and I took a working electric motor out of an electric lawn mower. We suspect it is a single-phase AC induction motor (correct me if I'm wrong) with a starter capacitor (pictures above). ...
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2answers
112 views

Maximum power for a 12V solenoid

I have a 12V 8A 35mm-stroke solenoid from eBay (similar to this listing) which I am powering with a 12V 20A PSU. I am using two of them for a homemade pinball game. At the moment they are hooked up ...
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98 views

What is the purpose of a capacitor in an ideal op amp schematics?

I'm trying to understand the purpose of the capacitor C which is in parallel with the resistor R3. Current sources IB are indicative of the current offset which was the part of the lecture we had ...
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1answer
73 views

Is my calculated capacitor sign correct?

I have the following circuit where I would like to obtain an analytic expressions for the value of \$Cs\$ and \$Rs\$ only kowning the phasors \$\bar Vina\$ and \$\bar Vinb\$ there displayed, I don't ...
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2answers
84 views

Cause of blowing resistors

Around 10 years ago we bought 3 dimmers for lighting at a venue. In the last year all three showed the same problem: one or multiple resistors of the dimming circuit (6 channels per dimmer, therefore ...
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45 views

KVL in the capacitor during transient analysis

I can see that this topic has been discussed many times in this site. But I still can't figure out why I am still not getting my correct equation applying the KVL. Consider a circuit as shown: ...
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83 views

Capacitor in the circuit - Bypass capacitor

I was trying to measure the supply current of a CAN transceiver during fault conditions, one thing which I noticed was that during CANH to GND(when the current consumption is supposed to be the ...
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2answers
68 views

How are capacitor voltage ratings chosen

I'm reading a user document of a dev board. On page 12, there is an explanation of the power management subsystem. The board VBUS and VBAT lines have a decoupling cap rated at 6.3V, whereas the output ...
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4answers
159 views

Using enameled copper wire as a capacitor for measuring water level in a tank?

I'm trying to make a capacitive water level sensor using two enameled copper wires used in transformers. I've used sanitary silicone to insulate the bottoms of the wires. (Coating is insulated by ...
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93 views

Trapezoidal Rule of Complex RLC Circuit using MATLAB

I am having difficulty trying to figure out how to solve this circuit using the trapezoidal rule. I know how to do so in a first and second order RLC circuit however this particular circuit is giving ...