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

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8
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4answers
908 views

555 timer: how to set values to take an hour

I'm new (and novice) in electronics. I came to seek your knowledge to see if someone can help me with a very basic circuit. It is a 555 chip, which should light a LED (for about 1/2 second) every ...
0
votes
0answers
43 views

Self tuning 125khz RFID reader

I have a RFID reader based on the EM4095 IC. I would like to make the reader self-tuning so it can handle varying inductance in the antenna due to reading tags near metal. I had thought of using a ...
1
vote
4answers
457 views

Turn a transistor on when any one of nine LEDs is on using an LM3914

I'm wanting to turn a transistor on when any LED from LED2 through LED10 are on with an LM3914 in dot mode. Basically, I want the transistor to be normally off until at least LED2 begins to light ...
-1
votes
1answer
80 views

How can they manufacture a high fara capacitor (1F, 100F)?

In the theory, the capacitance of a capacitor can be calculated by formulas C = epsilon x A / d. And if we use this formula to calculate the area of a 1F capacitor(with d = 1m), the result of A is a ...
0
votes
1answer
51 views

How many pulses are required to charge the capacitor to 20V?

A series of current pulses of 10mA amplitude and 2ms duration are applied to an initially-uncharged, 5 uF capacitor. How many pulses are required to charge the capacitor to 20V? I thought of this ...
4
votes
2answers
77 views

MAX682 with electrolytic capacitors

In a new design I would like to use the MAX682. In the datasheet I found this typical operating circuit: I would like to use it exactly like that except that I'm going to pull /SKIP to GND. In ...
0
votes
1answer
65 views

Make three respective LEDs blink with an LM3914 in dot mode

I'm trying to figure out how to make in the below schematic, LEDs D2, D3, and D4 blink respectively while the LM3914 is in dot mode when their on state occurs. Basically this would act like a warning ...
0
votes
4answers
88 views

LM317, basic voltage regulator, why does it get hot when not connected?

I have built this little voltage regulator circuit: circuit diagram I am a hobbyist, so these may well be screamingly obvious questions. I ask because I haven't found the answer to my first question. ...
0
votes
1answer
65 views

What are the failure modes of resistors, inductors, capacitors, diodes, transistors in conditions of overvoltage or overcurrent? [on hold]

What are the failure modes of resistors, inductors, capacitors, diodes, transistors in conditions of overvoltage or overcurrent? Example: ...
0
votes
1answer
35 views

Does a VPWR capacitor on a high-side MOSFET switch guard against inductive kick back?

We use three Freescale MC33982 high-side switches in parallel to drive a DC motor, and our electrical engineer suggests that a 50V, 10uF capacitor on the VPWR pin (then to ground) will guard against ...
0
votes
0answers
86 views

I think I have burnt my 24V DC motor

I had a 24V DC motor connected to a Polulu motor driver which was connected to an arduino uno board. I accidentally connected a power supply instead of a volt-meter to both ends of the motor while in ...
0
votes
0answers
25 views

Diffence between a magneto-resistometer and a capacitative displacement sensor [on hold]

I'm going through the specifications of a side project trying to replicate an equipment. A magneto-resistometer to measure displacement on a flexure is used. I started to look for prices, and the ...
1
vote
2answers
123 views

Does a capacitor discharge itself when the charging voltage becomes 0?

I am charging my capacitor with a binary pulse train (either 1V or 0V). I notice that when the voltage stays at 0V, the capacitor discharges itself. As shown, the green curve signal is connected to ...
1
vote
6answers
415 views

Need to build a circuit resembling fluid flow through porous media

I am trying to use electronics analogy to build a model that describes fluid flow in a porous media. For example I consider voltage, current and resistance to be equivalents of pressure, flow rate and ...
2
votes
1answer
64 views

Can I replace capacitor with multiple lower value capacitors in filter?

Can I replace higher capacitance value MLC capacitor in Sallen-Key topology filter with 2-3 lower value capacitors in parallel (with total capacitance equal to replaced cap)? I tried it in TINA-TI and ...
1
vote
2answers
105 views

How do I reset a capacitor once I have a signal rise?

Once the signal rises to a certain level, my capacitor starts getting charged. Once the signal falls back down to that same level, my capacitor stops charging. This way, I am using the voltage of ...
0
votes
0answers
29 views

Problem on finding the charge transferred and voltage between capacitors

The goal here is to solve for the voltages between capacitors (i.e. voltage in C1, Cx, C2 and CL). I am aware that during this time the Voltage in C1 is equal to the node voltage at node A because it ...
0
votes
2answers
53 views

Protecting a circuit from the effects of a capacitor's charging

During its first outing, I managed to burn out the (control circuitry) of two of the batteries connected to my LED jacket (see this, this and this question for context.) I thought I should have been ...
1
vote
2answers
61 views

Problem with a circuit of an controlled variable voltage source

I have this circuit, it should regulate the output voltage between 15V and 0V. But the output I get when I simulate it is between 2V and 3V, and when I implemented, I burned zener diode 1N4734A. ...
2
votes
1answer
71 views

Can I extrapolate the rated overload spec of a wirewound resistor to a joule rating?

I'm considering using a Vishay FVT series resistor for precharging some capacitors. Capacitance: 3300uF Voltage: 730V Resistance: 500 ohms Resistor continuous wattage: 25W This series, like many ...
0
votes
1answer
59 views

How to light a LED from capacitor [closed]

how much capacitance is needed to light up 3 volt 5-leds for 15 seconds...
0
votes
0answers
48 views

Capacitor node voltage problem

What might be the reason why the voltage on the other terminal of the auxiliary capacitor C7 and C8 connected with CKPb and CKP, respectively gets lower than its input? (i.e. input 1.7849V => output ...
0
votes
2answers
83 views

Supercapacitors vs. High Voltage Capacitors with Inductive loads used in CoilGuns or Solenoids

I'm looking for some insight on whether an 1000 Farads at 2.7v or 5.5v would be more effective than say 10,000uF at 400v-450v when creating a strong magnetic coil. The intent is something similar to ...
0
votes
0answers
39 views

SC circuit equivalent

Can someone help me find the equivalent SC circuit for figure 3? Just like in figure 2 with its equivalent circuit in figure 1. I'm just confused with the drain of M6 connected to gate of M2 at node ...
0
votes
1answer
78 views

Is this a dual cap?

As you can see below , this cap is marked 8 + 8 uf. Does this indicate that it is a dual cap? There only seem to be two actual terminals, as you can see here , although there are also three lugs ...
0
votes
0answers
78 views

Finding the value of capacitance for a given circuit

How would you know how much capacitance you should use in your circuit or is there any formula to compute on the desired capacitance you should use on your circuit? I have this circuit (figure shown ...
1
vote
1answer
98 views

What does lumped element mean?

Can anyone explain me the meaning of lumped element and lumped circuit abstraction in detail. What does lumping or discretizing matter mean?
7
votes
2answers
707 views

How does the MAX232 double the voltage?

MAX232 Datasheet Hi, I am currently a student so bear with me please! I'm currently using a powering the MAX232 with 5V DC, and when I measure from VCC to lets say, pin 3, I am getting a voltage ...
4
votes
4answers
866 views

Why is the capacitor short-circuited in this example?

Please forgive me if anything wrong in my question. I am a school student. I have following circuit diagram: simulate this circuit – Schematic created using CircuitLab There are three ...
0
votes
1answer
77 views

S parameters of a capacitor

I am struggling to understand S parameters. As an example, I am considering the S matrix of a capacitor in series with a transmission line. It has two ports, so must be represented by 2x2 matrix. But ...
0
votes
2answers
61 views

Capacitor leakage and design for low energy battery powered devices

For the design of a portable battery operated device, I have some power circuitry which requires a DC-DC converter and some other regulators, battery charger IC etc. While in the process of ...
0
votes
1answer
57 views

Where does the power absorbed of this capacitor come from?

In my circuits book, the voltage across a capacitor is given as \$v(t)=100\cos({2\pi60t})\$. Because \$i_{ab}=C\frac{d}{dt}v_{ab}\$, we naturally compute the current as ...
14
votes
7answers
1k views

Does changing the gap between plates change the capacitor voltage?

Consider an ideal capacitor which has a length of \$\ell_1\$ between its plates. The capacitor terminals are open; they are not connected to any finite valued impedance. Its capacity is \$C_1\$ and it ...
0
votes
0answers
48 views

Boost starup of a motor with a capacitor

I have a RC car and I wonder if its startup speed will increase if I mount a capacitor in parallel with the battery. My thinking is that while the car is idling the capacitor will load. When I start ...
1
vote
2answers
65 views

My voltage multiplier (cockroft-walton) will not charge my capacitor bank past 150v. How can I fix this?

I got 5 free 450v 4700uf capacitors that I put in parallel to form a 23500uf 450v capacitor bank (2.4kJ) in hopes of building a can crusher and later a railgun. I built a voltage tripler from four ...
0
votes
0answers
21 views

Help with solving a three phase power with delta-connected capacitor

I know it is a homework problem and I hate to ask for help, but I really need to work this out and I have no clue about it. I don't need you guys to work it out for me, just tip me some concepts or ...
2
votes
2answers
120 views

Capacitor Stacking Charge Pump

I have an infrared LED that needs a voltage drop of ~1.55V as well as a BJT to sink the current when the LED is in operation. That give me a total voltage drop needed of ~2.2V and unfortunately I have ...
0
votes
1answer
66 views

Why is there heavy oscillation in my capacitor discharge circuit and is there anyway to fix it?

I have the following capacitor discharge circuit: simulate this circuit – Schematic created using CircuitLab When solving for the voltage across the primary and secondary inductors, I ...
0
votes
0answers
46 views

How do I solve for this circuit? (Coupled inductors)

I am trying to solve for the following circuit (mainly getting a function of voltage on capacitor C): However, I tried my best using node voltage method or mesh current method, in time domain and ...
0
votes
2answers
79 views

Series capacitor equivalence

I have capacitors of 100uF, 10uF and 1uF; and need a series circuit with these capacitors to form a 0.1uF capacitor, is this possible?
0
votes
1answer
72 views

Help me hack this other speaker: Where would I introduce two different DC voltages?

I already asked a question about a similar speaker. I am also trying to convert a larger speaker in the same fashion. I open the speaker, and can identify the power supply and rectifier (I believe) ...
1
vote
2answers
131 views

Op-amp differentiator and integrator circuit: resistor and capacitor values

I don't understand how to determine value of resistors and capacitor in differentiator and integrator circuit of Op-Amp. I tried to align the amplitudes of these sine waves. I keep changing their ...
2
votes
1answer
67 views

Contactor control circuit

I am trying to understand a contactor control circuit that I took apart from a broken GIGAVAC GX14BAB. Here is a list of parts that I think are the closest representation of what is on the PCB: ...
1
vote
2answers
88 views

Are large electrolytic capacitors necessary in a servo system that doesn't need to be precise

I have two servos in an autonomous sail boat. One controls the rudder, the other the winch. I try to use both sparingly to minimize power consumption, and so I disconnect each unused servo through an ...
0
votes
3answers
141 views

What does an inductor's current stabilize to in DC?

As you can see from the below graph, after an inductor is turned on, the current is stabilized to approximately 6.5mA. My question is: what does the 6.5mA represent? Where did that number come from? ...
0
votes
1answer
49 views

Safely shutting down 19V mini PC when power fails

I am adding an Intel NUC (4"x4" i5 PC, 12-19V, 10A@19V) to my guitar effect pedalboard for all kinds of fun signal processing with Ableton Live and Max/Msp. I'm building a 12V 20A power supply using ...
3
votes
3answers
220 views

Basic question on capacitor usage

I'm currently learning electronics and I have some difficulties to understand capacitors in direct current circuit. I read a lot on it and I understand the basic principle but I don't understand why I ...
2
votes
0answers
66 views

Optimal Capacitor Placement on DC/DC Convertor

I'm trying to decide on the best layout for caps on a DC/DC converter. Which of the following options (or another, unlisted option) is the best choice? GND Out plane with 5V Out going the opposite ...
1
vote
2answers
147 views

How does the voltage go negative on the BJT base in this simple flasher?

I'm trying to get more specific in my understanding of electronics, and, like any adult learner, am realizing I have to correct some basic misunderstandings or gaps in my knowledge of fundamentals. ...
10
votes
3answers
872 views

Parallel Capacitor Conundrum [duplicate]

I have recently taken on a project that involves improving a circuit and there is a couple of instances where there are two capacitors in parallel with each other. The values of these capacitors ...