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

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1answer
46 views

Shielding a long cable

I was reading about the LM35 and i found this, he suggested that i must use shielding over long distances, which makes sense, but then he said i must add a capacitor and a resistor, why did he add ...
1
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0answers
27 views

From RLC prototype to signal flow graph

This simple 3rd order low-pass circuit simulate this circuit – Schematic created using CircuitLab can be described with the following 3 equations: $$-V_1 = \displaystyle \frac{-1}{sC_1} ...
3
votes
3answers
214 views

Why do capacitor datasheets avoid directly giving the ESR value?

Most datasheets give a parameter called "loss tangent" instead of directly giving the ESR value. Why don't they just give a numeric value for it? Why is loss tangent preferred over ESR? Is there ...
0
votes
2answers
52 views

Voltage regulator capacitor size

I want to use a LF33 voltage regulator to power a nRF24L01 module from a Arduino Pro Mini. I plan to power the Pro Mini with a 9V battery, then use it's 5V internal regulator to power the LF33 which ...
0
votes
3answers
86 views

How to find the positive wire on wall charger

i have a TPLINK wall charger from my old router. It's almost new and i would like to use it for my 5V regulator project. The prboem is that i dont know which of the 2 wires is positive and which ...
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1answer
41 views

where can I find a 5 cell Lithium ion battery voltage capacity percent level LED indicator [on hold]

I would like to build a 5 cell Lithium Ion Battery Voltage Capacity Level LED Indicator. This link shows a claimed 1 - 4 cell Lithium ion battery voltage capacity percent level LED indicator, 18650 ...
0
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2answers
72 views

Odd results solving this very simple first-order RC circuit

Here's the circuit: I'm trying to find the differential equation for the current through the capacitor (i_c(t)). Using KCL at the top node, I know that ...
0
votes
1answer
49 views

external power treatment in the powered board

I'm working with an audio board (company project) that is powered by a external 9V power supply. Actually an ordinary AC adapter, like this one: http://www.sweetwater.com/store/detail/MAud9v500. The ...
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0answers
41 views

Identifying a capacitor in a LG computer monitor [closed]

I'm trying to fix a LG L246WHX computer monitor with a blown capacitor, but have been unable to work out which capacitor I need to buy. It's a tiny blue (ceramic?) coin-shaped capacitor, only about ...
-1
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0answers
39 views

Powering high power LEDs [closed]

I want to power some high powered LED (R2) with this circuit. I would like the LED to be on for about 1 minute and they discharge C1 via R2. When C1 charges SW1 is open and the LEDs are off. When ...
3
votes
3answers
311 views

Layout of decoupling capacitors

So I've been attempting to create my first development board and layout. I'm first working on the decoupling capacitors, power and ground portions of the layout. The MCU I'm trying to properly ...
52
votes
14answers
5k views

My understanding of RC circuits is broken

I asked a relatively simple question. Unfortunately, the answers provoke far more questions! :-( It seems that I don't actually understand RC circuits at all. In particular, why there's an R in ...
11
votes
2answers
2k views

Is a capacitor a high-pass filter or a band-pass filter?

This has been bugging me for a while now... Does a single capacitor, on its own, behave as a high-pass filter or a band-pass filter? In a crystal radio set, you use a single capacitor as the tuning ...
0
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1answer
111 views

Capacitor discharging

I just started with small projects with capacitors, like astable multivibrator and I do not understand where the capacitor discharges. The theory always show the capacitor charged by the battery, then ...
0
votes
3answers
103 views

Is it possiple to discharge the positive charge only from a capacitor and maintain the negative charge?

Is it possiple to discharge the positive charge only from a capacitor and maintain the negative charge ?
0
votes
2answers
65 views

Use expensive or inexpensive capacitor for decoupling

I'm in the middle of a project to create a small development board using a 100Mhz Cortex M4 MCU and have to buy some decoupling SMT capacitors. I've found the following options: Cheap 10 cent from ...
7
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1answer
1k views

Do capacitors need to be blown or bulged to be bad?

The title says it all, I'm wondering if an electrolytic (or any other type) capacitor needs to be bulged to be bad?
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1answer
72 views

Capacitor 1 micro farad doesn't show any resistance reading

I have a capacitor labeled 1 μF (micro Farad) and when I measure capacitance I get 1 μF but when I measure resistance the meter shows out of range on any dial ...
1
vote
2answers
38 views

Big capacitors measurement(LCR meter related)

I digged up some capacitors from amplifier and decided to test them, one of them is said to be 8200 uF, the other 4700 uF. I measured them with LCR meter and it gives very strange numbers. If LCR ...
3
votes
3answers
82 views

What is the voltage source and ground on an antenna?

I've seen a few diagrams relating to AM demodulation, and I can't for the life of me figure out where the voltage source and ground come from in an antenna. From what I understand, an antenna can ...
2
votes
1answer
202 views

Amount of heat developed in capacitors

simulate this circuit – Schematic created using CircuitLab Q10 is equal to 10μC. No charge on C2. I need to find the amount of electric work that is converted into heat, from the moment ...
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vote
0answers
84 views

Voltage Doubler Circuit

I currently have a 25 stage voltage doubler circuit I am using 50 0.1 uF x2 suppression capacitors, 50 1N4007 Diodes, and a 20 Mohm current limiting resistors at the final emitter stage. I am using ...
-6
votes
0answers
64 views

What's your electronics design question? Be specific [duplicate]

What are difference in this two circuits? We can find decoupling caps and a filter. Since filter should be of 88Khz and decoupling capacitors change it's value. It's correct to put filter after ...
5
votes
3answers
439 views

Decoupling caps in circuit schematics difference

I want to ask if there is differences between this two circuits: I ask this questions becouse in different schematics like this: There is two decoupling cap of 0,1uF, it's a mistake or are ...
0
votes
1answer
60 views

How to activate a touchscreen device without human interaction [duplicate]

I need to be able to activate apps on my iPad without human interaction. We have tried dropping batteries onto the screen but that only works if dropped within a few inches. Is there any material in ...
0
votes
6answers
162 views

How do you find the voltage across a capacitor at time t= 0 and t = infinity?

Here is a diagram of the circuit, I am confused about problems a and b. How do I go about solving these two problems? Thanks! By the way you don't have to tell me the answer, I just want to ...
1
vote
2answers
67 views

using a capacitor for an off-grid system

New to the side and have very little knowledge on electrical systems. I'm trying to come up with a good off-grid system for my small house and have the idea of a PV array with a battery bank, charge ...
0
votes
2answers
86 views

Is there a significant loss in a voltage doubler circuit?

I am making a small generator just for experimentation. I need to double the voltage that the generator coils are producing. But I can't just connect them in series, because they are out of phase ...
0
votes
4answers
131 views

Capacity of a capacitor fully charged vs half charged

I read in most places, when people ask "can I replace a 10v 10uf with 100v 10uf?" and everybody answers "it's the same". Well... how can it be!?, I have a comparator circuit, that uses a little ...
0
votes
1answer
60 views

Capacitors Not Charging Uniformly

I have 2 identical PowerStor Series XB supercaps connected in series. Voltage rating of each is 2.5V. In series their capacitance is cut in half but the voltage drop over both of them should be ...
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votes
0answers
10 views

Resetting an arduino with a timer or sth similar [migrated]

I want to run an arduino autonomously - but although i apply a watchdog sometimes the systems hangs and can only be restartet by physically interrupting the power-supply (or hitting reset). So i need ...
0
votes
3answers
81 views

Slightly weird astable oscillator in a 555, where does this capacitor discharge to?

In the 555 datasheet, the cap is usually connected to pin 7 (discharge), but in this circuit, it's not: When the capacitor voltage is >2/3Vcc, output will turn off and current will have no where to ...
0
votes
2answers
58 views

Does the MC7805CT-BP need capacitors?

As far as I know, you have to put capacitors on most voltage regulators. However, the data sheet for this one specifically says "No external components required" and furthermore goes on to state ...
23
votes
5answers
3k views

How does a capacitor smooth energy?

I'm trying to wrap my mind around how capacitors work. I understand they store a charge and generally understand how but I don't understand how using them "smoothes" the flow of the charge. Doesn't, ...
5
votes
3answers
281 views

Distribution of electrons in a capacitor charge circuit?

Consider the circuit below: Let us say that the red dot's represent negative charges (electrons) and the blue dots positive charges/holes. Can we say that the distribution of electrons (red dots) in ...
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0answers
58 views

Equivalent capacitors

Consider the arrangement of two parallel capacitors in 1a . As concerns the electrostatic phenomena , the equivalent circuit is that in Sch.1b . The electrostatic interaction between the ...
3
votes
1answer
113 views

How can one measure extremely low-uf capacitors?

I'd like to measure (to a few percent precision) the capacitance of a 0.8-0.06pf variable capacitor (eventually to be read by a 120mhz 32-bit microcontroller, if that's any help). I realize that one ...
0
votes
3answers
108 views

Discharging capacitors upon power loss

I have designed a power delay switch which is intended to cause a short delay while a reservoir capacitor fills up before giving power to my microcontroller due it needing a short burst of high ...
0
votes
1answer
95 views

Capacitor Charging

Just a quick question, because i want to know if its possible. My son asked me if a kind of light harvesting robot could be made. That roams around, finds light, then charges, then runs around ...
1
vote
2answers
176 views

Power from a capacitor

I need to discharge a lot a energy in a short time from a capacitor, I don't have the numbers yet, but my question is if the power of a capacitor is limited for some others parameters of this. ...
2
votes
1answer
104 views

Equivalent Simplified Capacitor circuit

Schematic created using Multisim I'm trying to find the equivalent capacitance for the above diagram between nodes b and c but I'm having a lot of trouble understanding which capacitor is in ...
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votes
2answers
379 views

How do i build a battery charge circuit that doesnt require the battery to be disconnected

I am needing some advise on how to build a circuit that can charge a 9v rechargable whilst it is still connected to my small robot. The battery will power an arduino, meastro, 4 std servos and 2 dc ...
0
votes
2answers
61 views

Can You Swap Two Capacitors With Different Ratings? [closed]

I've bought a broken receiver recently and I need to swap out a few of the capacitors. the original capacitor is rated at 100v and 0.01uf. The local electronic store sells 100v 3.3uf capacitors. ...
4
votes
4answers
815 views

Microcontroller shutting off because of brief loss of power, can a capacitor fix this?

I have a microcontroller hooked up to a 5v supply which goes through a voltage regulator stepped down from 12v. I'm assuming that it's rebooting because it's possible that the voltage drops quickly ...
2
votes
4answers
138 views

Why isn't IC1 a comparator?

This is with reference to a circuit i saw in The Art of Electronics.The authors claim that IC1 is an integrator and that the circuit ensures that a current of magnitude |Vin|/(200k) constantly flows ...
0
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0answers
50 views

Calculate voltage in circuit with capacitor [duplicate]

I have a circuit where I have a capacitor (2F) in series with a resistor (1 Ohm) and a voltage source (v(0) = 10V). Now I am supposed to calculate v(t) for different t, like t=1s, t=2s and so on. ...
1
vote
4answers
82 views

Analyzing an op amp circuit (transfer function) that does not match the basic cases

At the following circuit I want to find what it does and basically its transfer function. I've searched a lot but I didn't find any circuit like this. Since it does not match any of the basic types of ...
0
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3answers
120 views

Output capabilities of super capacitor

I have come across a question that is very near and dear to my heart and I am in the hopes that somebody can answer this new years eve question of mine per se. So I am wondering, if I were to run ...
0
votes
2answers
68 views

Can I feed lower than rated voltage?

I'm poking around on eBay for some capacitors to use in circuits which I'm working on and see that they have a rated voltage. After some quick research, I found that going over the rated voltage of a ...
4
votes
1answer
148 views

Understanding The Art of Electronics mathematical explanation for capacitors

The author mentions that the reader should not worry if they cannot keep up with the mathematics, I however feel uncomfortable doing so. The issue is the fact that the author does not explain what the ...