Tagged Questions

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

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2
votes
1answer
78 views

PIC18 not working when wiring 30pf capacitors of cristal resonator to ground

I'm using pic18 with external oscillator 16MHZ 16M HZ HC-49S Crystal Oscillator with two 30PF capacitors configuration OSC = HS using breadboard, when wiring the ...
1
vote
1answer
105 views

The safety of the capacitor

I saw this material for making capacitors (http://www.capacitorfilm.com/web/enproduct.aspx?ch=64). It said capacitor with the material is very safe, does anyone know what is the principle under which ...
-2
votes
0answers
43 views

How to calculate when a capacitor would explode? [duplicate]

Given a non-polar capacitor, how would I calculate at which voltage would it explode?
1
vote
1answer
40 views

Finding equivalent capacitance part II

Here's part I! They helped me a lot. But this problem is harder so if you can tell me where, if, I went wrong. When first switch is closed, the other one's opened. And in reverse. Here's solution ...
-2
votes
2answers
82 views

Finding equivalent capacitance

Sorry, for the quality, someone could do this in the editor but I think you can see what's what. That is a switch in middle. How do you find capacitance when p(switch) is closed, and how when it's ...
0
votes
2answers
80 views

Why don't over damped and critically damped circuits oscillate?

The reason underdamped LRC circuits oscillate is because the energy keeps flowing between the inductor and capacitor. The energy is being constantly exchanged between the capacitor and inductor ...
0
votes
1answer
31 views

Capacitor with n electrodes

In my book it says that the capacitance in a capacitor with n electrodes is (n-1)*Co, Co is a capacitance of a two parallel plates capacitor. I know how to distribute charge when there are 3 parallel ...
0
votes
1answer
65 views

Why isn't this LM2917 circuit working to turn off a transistor?

It was suggested to me that I should post a new question (original question here: Minimal Hall effect sensor circuit to keep something off after certain RPM achieved). The below schematic is for ...
1
vote
2answers
70 views

Digital trimmer capacitor

We would like to design an FM transmitter module for Arduino boards. Therefore, we are in need of a trimmer capacitor that can be controlled digitally. Do digital trimmer capacitors exist or do you ...
0
votes
2answers
89 views

Does current flow stop when a capacitor is fully charged?

If I take a 1V battery and a 1 farad capacitor and a bulb and connect them in a circuit. Then will after the capacitor gets charged (not fully charged as that is impossible) will the bulb gradually ...
1
vote
3answers
80 views

Replacing capacitor from unworking TV with some other capatitors which has not the same value [closed]

I am repairing (trying to repair) my TV. I found 1 capacitor 25V \$1500\mu\$F which i think is bad (it has some weird shape at top) I don't have any capacitors with that value but I have some similar ...
6
votes
1answer
268 views

What is the purpose of a capacitor in the feedback path of a unity gain buffer?

First time using this site, I'm an EE student and have been studying opamps. So far in class we have only discussed 'ideal' opamps, but I saw an opamp with this layout and was wondering if anyone ...
0
votes
0answers
35 views

Switch capacitor analysis without initial condition

The figure below is described as: C1 and C2 are the pumping capacitors but at given time and conditions of clocks (VCk and VCk'), C1 is being charged while C2 pumps its stored charge to CL (load ...
24
votes
3answers
2k views

Why do they crimp capacitor leads?

Most manufacturers produces crimped and straight lead pairs of their capacitors which has exactly same capacitance and voltage rating. Why do they bother crimping the leads? What advantage does it ...
0
votes
1answer
64 views

Buffer Capacitors [duplicate]

What does a buffer do? In the given circuit,it is said that capacitors C1 and C4 act as buffer .What is their role here?Can't we just replace them with pull-down resisrors?
8
votes
4answers
995 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
46 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
467 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
85 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
53 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
79 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
73 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
98 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. ...
-1
votes
1answer
90 views

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

What are the failure modes of resistors, inductors, capacitors, diodes, transistors in conditions of overvoltage or overcurrent? Example: ...
0
votes
1answer
37 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
90 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 ...
1
vote
2answers
129 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
425 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
66 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
108 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
33 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
57 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
62 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
72 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
0answers
50 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
90 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
79 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
102 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
713 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 ...
5
votes
4answers
872 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
80 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
63 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
73 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
123 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 ...