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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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35 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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0answers
19 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
45 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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3answers
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
97 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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0answers
53 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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0answers
28 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
178 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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39 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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39 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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0answers
19 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
766 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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44 views

HV Capacitor power [closed]

Hi does anyone know what kind of high voltage power DC supply do I need using UK 50Hz to charge a high voltage capacitor 50/25kV.
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2answers
56 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
86 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
71 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
34 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
135 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
54 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
71 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
34 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
72 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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0answers
61 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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0answers
35 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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0answers
103 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
35 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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1answer
71 views

Help me get an idea of where to start with this problem [closed]

Where would I begin and what steps would i take to determine I1, if V3 is 690V?
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0answers
23 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
80 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
94 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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0answers
90 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
70 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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0answers
41 views

Capacitor sizing in Grid connected PV system [closed]

How can I determine the size of DC Bus capacitance in a Grid Connected PV system?
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2answers
77 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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0answers
38 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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0answers
76 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
56 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
144 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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1answer
66 views

Series RC circuit phase difference [on hold]

I have a series RC circuit . AC sine wave source peak to peak voltage is 4Volts.In I=V/Z formula I don’t know what should I write the Voltage.Should I write Voltage RMS value or Peak voltage value? ...
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0answers
70 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 ...
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1answer
86 views

In this Foster Seeley discriminator, what is the purpose of capacitor C3?

I understand the whole circuit, except for the use of capacitor 3. What's its purpose in here?
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2answers
56 views

How does this simple FM slope detector work?

I understand what happens from the diode onwards, it's a rectifying amp and a low pass filter that filters any unwanted frequencies from the carrier, but what is going on in terms of voltage between ...
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1answer
74 views

Purpose of high pass filter for AC Mains?

I wanted to ask what the purpose of the high pass filter does in the below circuit. Is it necessary?
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3answers
110 views

Battery indicator Circuit

Many of battery indicator circuits are designed using 2 or more leds like in the image above but how to design a simple battery indicator circuit using only RGB LED and transistor for 12v battery ...
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1answer
61 views

What is the current draw of a capacitor in a VOLTAGE BOOSTER

I'm trying to learn by myself the principles of a voltage boost converter. **BATTERY IS 1.2v@4300mAh I noticed that many sources* suggest not putting a resistor in series with the capacitor (as in ...
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1answer
59 views

Realise circuit for hFe measurement

To measure Beta (hFe) of the transistor you should zero u_ce (voltage across CE for the AC component in signal). To zero that component you put capacitor in parallel with transistor AND as shown on ...
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2answers
915 views

How can I deduce the power of a capacitor from its datasheet?

I am looking for suitable capacitors for a sound amplifier I have designed. The speaker power should be at least 7 watt (for the sound to be loud enough). (I attach a figure of the design) So, I ...
2
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1answer
71 views

3 phase motor running on single phase using steinmetz delta connection

How do 3 phase motors manage to run on single phase power using the Steinmetz delta connection with a single capacitor? I thought capacitors only shift the phase angle upto 90 degrees, whereas 120 ...
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1answer
59 views

Quality factor of RLC circuit

I am trying to calculate the quality factor for the response curve of a series RLC circuit. I measured the voltage across the capacitor at several frequencies and calculated its ratio to the forcing ...