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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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2answers
39 views

VI component tester not working properly when capacitor is placed parallel with diode

I am trying to repair mainboards with VI component tester. (Such as this device and that device.) I check the characteristic VI curves of the components on the card and identify the defective parts ...
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6answers
2k views

Placing bypass capacitors after VCC reaches the IC

I have a question about bypass capacitors and their possible placements. I am designing what I hope to be a double sided PCB, which has the VCC and the vast majority of the data lines on one side, ...
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1answer
82 views

What will be the real voltage along the line with a voltage source and a capacitor?

Take the following circuit: If I do a simulation of this circuit I get this graph: The strange thing is that in the simulator it gives the same voltage sine wave in the circuit, near the voltage ...
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1answer
31 views

charge capacitor in two phases

i want to charge two 25F Supercaps (in series) in two stages: while their total voltage is under 5v, i want to charge them slowly via a resistor R3 of around 100 Ohm. After they reach the desired ...
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1answer
86 views

Why does adding a capacitor greatly improve this circuit?

I've been prototyping this pretty simple circuit for a while now: simulate this circuit – Schematic created using CircuitLab Description: C3 is charged to set point. Compatator out put goes ...
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3answers
40 views

Could an external circuit with 74HC series IC reliably test a 24 MHz crystal?

I made a circuit where the microcontroller works. I made a duplicate of the same circuit with a working micro, but that circuit does not start and there is no smoke and the PCB is clean (no loose ...
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1answer
32 views

RF amp rating of ceramic capacitors

Some one posed a question about current ratings in a capacitor and the replies basically came across as a non-issue except for what might be induced due to ripple in various power supplies. But what ...
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2answers
38 views

Backup power supply using capacitors to help esp8266 run for 3-4 seconds after power failure [on hold]

I need to make a circuit with introduction of capacitors in parallel with input supply of esp8266(3.3Vdc) to run it extra 3-4 secs after power failure, Is it possible to gain extra 3-4 secs just ...
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2answers
55 views

Fake energy saver inductive loads

I watched this video on YouTube, it covered fake energy saving devices. I have seen many of these fake devices and they all seem to use a capacitor. My question is why would they bother? The person ...
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1answer
33 views

Cap in Series with a DAC Reverse Current

I'm using a 8-bit DAC: (DAC5311IDCKR) to generate a 1.5V Amplitude sine wave with a 3.5VDC offset. I've put high-pass RC filter across it shown below to block DC so that it becomes AC. I understand ...
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1answer
49 views

Impedance load matching

So I've done this so far, and know one of the components is a 50ohm resistor. However I dont know where to go from here. How do i decide if its an inductor or a capacitor? This is a past paper exam ...
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0answers
36 views

ESD Diode - clamping voltage

I'm trying to replace an existing ESD diode(PESD1CAN) in my application CAN circuitry due to some reasons, I've found an alternative ESD diode(RSB27C2), but compared to the diode that I already have ...
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2answers
72 views

Cheap alternative to limit inrush current (eg. relay bypassing a fixed resistor or MOSFET)

I'm editing the question because several (great) answers focus on the fact that the LTC3780 module (inside ajustable my power supply) can handle the inrush current (maybe, maybe not). I'm glad to know,...
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5answers
2k views

Heat lost in ideal capacitor charging

If we use an ideal capacitor to charge another ideal capacitor, my intuition tells me no heat is generated since capacitors are just storage elements. It shouldn't consume energy. But in order to ...
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1answer
44 views

Dotstar (APA102) LED strips decoupling capacitor on PCB

I am trying (based on very distant memories of EE in college) to design a fairly simple Arduino shield PCB to control several LED strips in parallel. Each strip would connect to its own 4 pin terminal ...
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4answers
1k views

relative price of a transistor and a capacitor

DRAMs achieve high memory density by storing each bit of information with one transistor and one capacitor. That got me wondering, how expensive is a capacitor relative to a transistor?
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0answers
37 views

Maximum power transfer theorem [duplicate]

Im very stuck on where to go with this question. The examples in class used complex numbers, where as this doesn't seem to need them. Im aware that Zs = Zl, but does Zl=Cl+Rl? Any help with how to ...
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1answer
64 views

Single transistor IR repeater

I need the IR repeater to pass IR (TV and so on) remote signal to remote devices in some box (pass the IR signal from outside the box). So, I bought a cheap IR repeater on single 2TY transistor, 4838 ...
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2answers
69 views

Using a capacitor instead of inductor in a switching regulator, and viceversa

Contextualizing more: In a switching topology, and I am butchering it now, the inductor gets "charged", and eventually will keep an amount of energy "just enough" required for the load. This is ...
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2answers
55 views

Voltage spike at the coil when opening the switch [duplicate]

I've the following circuit: simulate this circuit – Schematic created using CircuitLab In my book they stated the following sentence: After that the switch is closed for a long time, I let ...
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2answers
44 views

The pros and cons of tantalum and ceramics in AMS1117

Task: Make a reliable power supply for sensors and an RFID card reader. Specifications: Total current consumption: up to 0.7A (700 mA.) Elements supply voltage: 3.3V Input voltage: 5V Working ...
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0answers
19 views

How to use a singe transformer with the same effect as 2 in series

For a small project, I would like to know if it is possible to use a singe transformer, and a capacitor to effectively step up the voltage twice, E.g. Two of the same in series. If so, please explain ...
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2answers
58 views

Finding time constant in terms of R and C

I got a different expression for the time constant than the actual solution. Can anybody tell me where I went wrong? Why is it that in the solution all three resistors were put in parallel? What do ...
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2answers
70 views

Current in charged RC circuit

I've the following circuit: simulate this circuit – Schematic created using CircuitLab The capacitor is charged up to 10 V according to the following formula (when the switch is closed): $$\...
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1answer
46 views

Maximum safe working voltage of capacitors

The answer is 30kV. My method led to an answer of 41KV, where did I go wrong? I believe I cant just add the Vmax(s) at the end, but what would I do instead and why?
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0answers
55 views

Capacitor voltage rating for dual power supply

I'm currently building a LPF using a differential op-amp configuration and a multiple feedback topology. The opamp I'm using is the THS4131. I supply the opamp with a +/-12V power supply. My question ...
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1answer
55 views

Headphone Noise from Laptop SMPS

I have been facing an issue that has been a mystery to me for quite some time, and I wanted to see if someone here can potentially give me more insights on this so I can understand why it is happening....
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1answer
43 views

Is a higher capacitance rating ok for filtering?

I am newer to electronic design and bought the mpu6050 sensor chip, which the documentation can be found here: https://datasheet.lcsc.com/szlcsc/TDK-InvenSense-MPU-6050_C24112.pdf It says that pin 20 ...
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3answers
104 views

Capacitor circuit simplification

I am unsure if I have simplified this circuit correctly, therefore I am unsure how to write Vo in terms of V1. Please let me know if I have simplified this correctly.
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1answer
71 views

Aluminum Electrolytic Capacitor - current, power, efficiency

How to find out the efficiency of an aluminum electrolytic capacitor like this one. How to find out resistance of such a cap in order to calculate the time it takes for it to charge up or discharge? ...
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1answer
56 views

Unknown PSU blown capacitor [closed]

Hi, I have a 1988 laptop with a blown PSU capacitor (was located in c10). The capacitor still barely reads 395 (which an online calculator says means 3.9uf) and +35k which means 35v(?). 1) How ...
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2answers
45 views

Removing a charged coil from circuit

I have a question: If I charge a capacitor through a resistor and remove it from the circuit, the capacitor will be charged for a certain amount of time (eventually the voltage across the capacitor ...
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1answer
45 views

Two modes of electrostatic force with charged capacitors?

During a charged state of a capacitor (Regardless of the type of capacitor), Simple parallel plate: .png Parallel plate with dielectric material in the gap: ]3 Supercapacitor: How is the ...
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0answers
44 views

Accumulation of batteries' energy to rise electrical power capability

I am looking for a method to drive/pulse (ocasionally) an inductive load from a battery. The problem is, that the battery does not deliver enough power the load needs. But, energy is not a problem. I ...
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1answer
47 views

What are the specifications of this capacitor marked '3R910, R L'?

I have a battery charger circuit, this capacitor sits between the rectifier diodes and chunky set of inductors and diodes on the AC input side. The battery charger is 30A 12V car battery so pretty ...
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0answers
55 views

Finding the voltage across an inductor in a RLC circuit

Well, we have the following circuit: And I need to find the voltage at the node \$\text{Y}_1\$. My Work: The input voltage and current relation is given by: $$\frac{10}{s}=i_{in}(s)\cdot\frac{1}{\...
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1answer
49 views

RIFA PME271M547 replacement

I just broke my sewing machine (it's an old Viktoria machine about 30-40 years old) and now I am looking for a replacement safety capacitor. The one installed is a RIFA PME 271 M 547 paper capacitor. ...
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1answer
40 views

C=Q/U equivalence for inductor

In order to calculate the time it takes to charge a certain capacitor with value C at a given constant current of a value I to a voltage of value U, I can use: $$ C = \frac{Q}{U} = \frac{I\Delta t}{U}...
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1answer
30 views

What is the change in voltage across an inductor, or change in current through a capacitor?

The formula for voltage on an inductor is stated as v = L (inductance) x (di / dt) and current for a capacitor is i = C (capacitance) x (dv / dt) But I don't understand what the (dv/dt) part of ...
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2answers
53 views

what does Loss Tangent means in capacitor?

As we know the definition of Loss Tangent in capacitor which it is: When a sinusoidal alternating voltage is applied to an ideal capacitor, the current advances by pi/2 in phase. In the case of a ...
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1answer
41 views

Finding the equivalent capacitor

Given the following circuit: simulate this circuit – Schematic created using CircuitLab I'm trying to find the equivalent capacitor assuming that the capacitors are already charged. I'm aware ...
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2answers
126 views

Non polarized capacitor in schematics

enter image description hereI am restoring my Sansui AU 6600 Amplifier. I have taken out all old electrolytic capacitors, and my question is. From the part list for F 2092 capacitors C05 and C06 (10&...
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1answer
83 views

What are the main characteristics of high reactive power RF capacitors?

This question is related to this one. I have to design a high quality factor RF parallel resonant circuit, to be placed in parallel to the output of a medium to high power RF generator. Precisely, ...
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2answers
69 views

In Circuit Tester design

I wanted to create an ICT to check for shorts and validate some of the voltage levels on a PCB that I created, using a jig. I have placed probe points on the desired nets and will be using pogo pins ...
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0answers
24 views

Moving a capacitor in a time varying or non-time varying magnetic field?

1) If a simple parallel plate capacitor connected to a circuit, and discharging, were to move in an exterior magnetic field, what would happen to the interior region? Interior region components: ...
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0answers
25 views

(Very Basic) Confused on Reading a Datasheet and Calculating Inductor Ripple Current for a switching Regulator

I am using this component for a project, however, when reading the datasheet I have just become confused about a couple of things. Datasheet : http://www.ti.com/lit/ds/slvs569f/slvs569f.pdf I am ...
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1answer
486 views

Why are the capacitors necessary for a quartz crystal?

I read that it is recommended to connect 2 grounded capacitors to both ends of the quartz crystal. But that doesn't make any sense to me. Since capacitors have no resistance, wouldn't that make it so ...
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1answer
56 views

Ceramic Capacitors vs DC Bias - Derating rule of thumb misleading?

Premise Ceramic capacitors with Class 2 dielectrics (such as X5R and X7R) usually show a reduction of its capacitance value as the applied bias voltage increases. This behavior is more prominent in ...
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4answers
481 views

Is the capacitor placed correctly in the schematic?

I am new to electronics so any form of advise will be helpful. While trying to build a line-following robot by studying the circuit schematic(as attached), I wanted to find out what the capacitor C1 ...
2
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0answers
104 views

Discharging high voltage and capacitance capacitor?

I need to discharge a 4.4mF (millifarads) capacitor storing 1200V in about 5 seconds. I did the t=R*C' and got a resistance value of approximately 227ohms. I did a ...