Questions tagged [electrolytic-capacitor]

An energy-dense capacitor type, used in low frequency filtering applications.

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6
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3answers
3k views

Why are some capacitors bent on old boards?

I've noticed that on older boards some of the electrolytic capacitors don't sit up straight, they're not totally vertical. I wonder why this happens, is it because they were soldered by hand and the ...
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2answers
85 views

Can we use a capacitor with battery to fast charge it?

Consider this. Many capacitors connected in parallel to an input line, those capacitors are in series connected to battery. Whenever we need to charge, we plug in adapter that charges the capacitors. ...
2
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1answer
68 views

Reusing electrolytic capacitors?

Is reusing an electrolytic in a different circuit OK? Is the heat from desoldering liable to change the caps performance? Likewise going from lower operating voltage to higher, and vice versa?
8
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1answer
609 views

Why do these capacitors have an additional plastic block around them? What kind of capacitor is this?

Just saw these type of capacitors for the first time and I'm curious : Why do they have this additional block of plastic around them? Some kind of shielding? Is there some specific reason they didn't ...
0
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4answers
108 views

0.1 uF in parallel with larger >1 uF to reduce noise from IC

Back in the day when we would use an electrolytic capacitor across the supply of a IC we would always put a 100nf Ceramic in parallel because (if I remember correctly) electrolytics had inherent ...
0
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1answer
65 views

Are capacitor vents safe to touch?

I couldn't find this information anywhere. Every tutorial on how to safely handle a capacitor tells you to absolutely avoid touching the capacitors leads, and to grab a capacitor by its insulated ...
2
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0answers
74 views

What would be the cause of measuring AC voltage across a LM7805?

This is my first time here so I apologize if I don't provide enough information. I am trying to repair a centrifuge that is giving an error on its LCD display. Though the service manual doesn't say ...
-1
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1answer
62 views

How to size a capacitor?

I want to design a PCB with some ICs and I've read that it's recommended to use decoupling capacitors to filter out voltage spikes. There are three ICs on the PCB: Arduino NANO, nRF24l01 module and ...
2
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0answers
39 views

Question about series-connected (pseudo-nonpolar) electrolytics

Another Q&A on this site ("Ceramic caps vs electrolytic. What are the tangible differences in use?") contains good information on capacitors in general, including parameters I wasn't ...
2
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1answer
85 views

Unexpected (unintended) capacitor charging explanation

Please first consider the below schematic. It is the balanced output part of an existing hifi preamp. Not my design, it's confidential so I can only reproduce the relevant part. Things that might be ...
1
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1answer
85 views

How to calculate the needed capacitance of a start capacitor for a 12V 10A DC motor?

I want to use a 12V 15A switching power supply for a 12V 10A DC motor which has about 9A start current and 6A no load current, I also want to add a push button switch for on and off function to use it ...
0
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3answers
135 views

Fake ELNA electrolytic smd capacitor

Few years ago I bought "pack of SMD capacitors", they came only with information about capacitance and voltage. Now I need to use one of them, but I have trouble with find information what ...
9
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3answers
1k views

Can an electrolytic capacitor withstand 0.1 V reverse polarity?

Let’s start the question with a brief description of my application. I am trying to attach a headphone jack with a detect pin to a RDA5807 IC based FM radio project. I am using a separate ...
1
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0answers
56 views

Musical Tesla Coil / Slayer Exciter - Electrolytic Capacitor

Can somebody of you tell me, why the upper capacitance in this musical tesla coil needs to be an electrolytic capacitance? Tesla Coil audio music player circuit analysis
1
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1answer
81 views

Why could my electrolytic capacitor have current but not my parallel plate capacitor?

This is for a science project. I have built my own electrolytic capacitor with aluminum foil and paper dielectric soaked in salt water solution. My parallel plate capacitor is simply aluminum foil ...
2
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0answers
64 views

Can I repair this motherboard damage? [closed]

I accidentally knocked a SMD electrolytic capacitor off the motherboard of an ASUS laptop I was stripping down to clean. It looks like the copper pad came off with one of the legs. So My questions are:...
0
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1answer
136 views

Are aluminum electrolytic capacitors suitable for encapsulation/potting?

Because aluminum electrolytic capacitors generally incorporate a venting mechanism for over-temperature/over-pressure events, are they suitable for complete encapsulation in potting compound? ...
2
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2answers
144 views

Can my circuit be submersed in oil?

I've been asked if a design of mine can be immersed in transformer oil. (And still function properly!) The circuitry is mostly SMT Qs, ICs, Rs, ceramic Cs all of which I think are OK but I'm unsure ...
0
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3answers
91 views

Switched power supply capacitors

Lots of electronic hardware gets problems its psu and more specificly: with the electrolytic capacitors. How do old capacitors usually affect the capacitance of that electrolytic capacitor? What ...
0
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1answer
58 views

Decoupling capacitors - placement close to DC output

I have a general question regarding the placing of decoupling capacitors. Example at DC Vout of SMPS or LDO regulators. Does it really matter which capacitor out of 100nF, 1nF and 10uF is placed ...
0
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3answers
132 views

Replacing the capacitor on an old Philips amplifier

My Philips amplifier broke down (model FA153) and my friend told me it's likely the capicators have worn out (they were produced in West Germany ;)) I am quite the layman in electrical engineering, ...
0
votes
4answers
373 views

Orientation of an electrolytic capacitor in a circuit

I am attempting to debug the following circuit. Looking at the schematic, starting at Vin on the left of the diagram, I want to figure out if the 10uF capacitor is the issue with the circuit. This ...
2
votes
1answer
41 views

Use two 250V series cap in APFC instead of single 400V

I have a EVGA 500W PSU with an APFC which is causing spike noises, presumably from the APFC or main switching as they both run in sync controlled by the CM68000TX combo apfc switching PWM chip Noise (...
0
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1answer
52 views

Substituting a capacitor of different capacitance [duplicate]

If a circuit calls for a capacitor with a specific capacitance, what happens if a capacitor with a different capacitance is substituted? I have a circuit that calls for a 250uF capacitor to power a ...
0
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0answers
23 views

Ac current injecton to dc bus

I want to inject a 2V ac sine wave on a 480V dc bus. to protect my ac signal generator from entering high dc voltage I am going to use capacitor as coupling device. Ac generator also should deliver 15 ...
1
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1answer
49 views

Using SPST Switch as Button using Capacitor, which type?

Before I start, know that I'm still very much a beginner at electrical engineering. I'm building a switch box to be used for PC simulators using mainly (non-momentary) SPST switches and a USB encoder. ...
1
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0answers
49 views

How to Determine Input Capacitor Value for Peak Power Requirement

For flyback SMPS, how do we know that our input capacitor value is sufficient for some peak power requirement? I understand that bigger input capacitor will have more advantage on this peak power. ...
0
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1answer
54 views

Finding out capacitor polarity on pcb

I made the quintessential newbie mistake: I removed 2 capacitors (CF07/CF08) without noting down the original lead position. The interesting part is that the schematic (attached) seems to convey that ...
0
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1answer
114 views

24 AC to 32 DC. How?

I encountered the following problem: inside an equipment, an added PCB needs 32 V DC and in that enclosure, only 24 V AC is accessible. In order to get 32 V DC from that 24 V AC, someone put a bride ...
1
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1answer
65 views

Tiny 0.33 F Capacitor

I need to replace these (what I think are) capacitors, but the rating seems very high. They are smaller than the tip of my finger, yet the label pretty clearly says 0.33F, 5.5V. This seems wrong, as ...
0
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1answer
95 views

Can I change 1000 uF, 16 V for 1000 uF, 10 V?

Few days ago my main monitor did not turned on. I opened it and discovered three capacitors, of 1000 uF/16 V each, in bad shape. Since all stores here in my town are closed due the quarentine, I'm ...
2
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1answer
74 views

Remove electrolytic capacitors for a class-D amplifier

I'm referring to this schematic TPA3251 Evaluation Module, pg. 18 Question: Our current board design has an SMPS (flyback, 36V, ripple 50mV) & amplifier (TPA3251) in the same PCB (4 layer.) Due ...
2
votes
1answer
79 views

How to test if a capacitor is good if my DMM farad's range is less than the capacitor's

So I found out that my DMM maximum reading is 100uF (Though its price is twice the ones that reads upto 100mF, mostly because its 8 years old). It doesn't have manual range for capacitance measurement,...
0
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1answer
42 views

How to find out the values of a surface capacitor

Surface resistor has numbers on it to decide whether it's good or bad after measuring it with DMM. But when I looked at surface capacitors, they don't have numbers or strips to decide their validity ...
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2answers
496 views

How long do electrolytic capacitors last in seldom-used equipment?

I have a Fender solid-state amplifier nearing its 40th birthday. I've been going through it, replacing some failed logic chips and updating some of the op-amps (gaining about 10dB in S/N ratio!). ...
0
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3answers
56 views

When to not use electrolytic caps at the input of flyback converter?

This reference design does not use bulk capacitors at the rectifier output. It uses small ceramic capacitors. On the bright side, I like it because it eliminates the reliability issues of electrolytic ...
0
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2answers
125 views

Replacing these capacitors?

This is a controller board for a home ventilation system. It runs fine most of the time but sometimes the ventilation stops for one minute, then starts again and runs normally for anywhere between one ...
0
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0answers
53 views

Techniques for measuring the ripple current of SMD electrolytic capacitors

I am currently creating a test plan for an AC/DC converter (90VAC...264VAC -> 12VDC) I've been working on. Since the output electrolytic capacitors are of SMD type, I am trying to come up with ...
0
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2answers
134 views

22uF 0805 SMD capacitor for voltage regulator?

I'm trying to use some part of this circuit dual power supply circuit: http://embedded-lab.com/blog/multi-purpose-dual-power-supply-5-0v-and-3-3v-regulator-board/ Credits to embedded-lab.com. I ...
1
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1answer
28 views

Interpolation of electrolytic capacitor's dissipation factor / loss angle

It is a common practice for capacitor manufactures to define either the ESR or the dissipation factor (aka loss angle) at a given frequency (e.g. 120Hz, 1kHz or 1MHz). It is also clear that their ...
1
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2answers
443 views

Real world brushed DC motor bulk capacitance calculations

There's a lot of great information on driving DC brushed motors from h-bridges. Preventing back-emf with diodes and bulk capacitance from electrolytic capacitors When designing a high powered h ...
8
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2answers
7k views

Why do some SMD electrolytic capacitors have platforms?

I’m working on a computer monitor’s power board (to replace a capacitor or two, which I assume is the problem), and found these: Replacements are easy to find, so no issues there, but I’m curious why ...
0
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2answers
45 views

Electrolytic capacitor polarity voltages

What happens if we feed an electrolytic capacitor only positive voltages while keeping the negative pin voltage lower than positive. for example positive pin 20V and negative pin 5V. Does it affect ...
10
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1answer
1k views

Desoldering a through hole capacitor with weird terminals

Apologies in advance if this is the wrong place to post this question. So I've just RGB modded an old CRT TV, and now I'm trying to replace a series of capacitors to hopefully fix some screen ...
0
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1answer
86 views

Can failure of an old electrolytic capacitor be precipitated by motion?

I have report of a circuit board failure. The board was 20+ years old, and included at least one electrolytic capacitor. That capacitor would then be beyond its expected useful life. The board was ...
12
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5answers
3k views

High short circuit failure rate of aluminum electrolytic capacitors during the production processes

I have produced 1000 units of our new developed energy meter. Almost 20 aluminum electrolytic capacitors (2%) have failed short when we test them during the production processes. The Capacitor is a ...
1
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3answers
335 views

Charging 2 super capacitors in series

I have recently received my order of 2 2.7V 500F super capacitors from eBay. After much searching, my yet unanswered question is: Can I connect both of these capacitors in series and charge with 5V ...
1
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1answer
116 views

Coilgun capacitor reverse voltage in my schematic?

I'm going to build a coilgun and have thought about all possible problems, which I solved except the reverse voltage problem. I designed a schematic based on some other schematics I found online. My ...
1
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1answer
199 views

Can a smd aluminum electrolytic capacitor be replaced with a normal electrolytic cap?

I have a JBL Charge 2+ amplifier that during dissasembly I missed a major step and accidentally broke off about 2 to 4 of the SMD electrolytic caps. Instead of buying replacement ones I already have ...
-1
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1answer
445 views

What is the use of a capacitor in a DC motor circuit?

I'm trying to understand all the components I need in order to drive a DC motor through an Arduino. I saw this circuit below, which has a capacitor (other sources show same circuit but without the ...

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