Capacitor FAQ

Frequently asked questions on capacitor types, ratings, brands, use and abuse.

Re: Bigger input/output cap = more bass always?

Postby kriista » 16 Apr 2008, 23:35

Ordering some IC sockets to chop up into 2legged/capacitor versions so I can go all willynilly (and I thought I was the only person that used that!) on it.

I know that when you put caps in parallel you add the value, but I think it changes the voltage(or current?) going across. Is that of any significance in this application?

Like, can I mix/match caps to get the right value I want without the operation of the circuit being affect by a voltage(or current) change?

Or does it not matter since this is just going to ground?
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Re: Tantalum caps?

Postby JiM » 26 May 2008, 09:20

It's often because of the "equivalent series resistance", which is lower with tantalum. And also better emperature stability, no long-term electrolyte dry-out, etc ...
http://www.low-esr.com/electcompare.html-ssi
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Re: Tantalum caps?

Postby modman » 19 Jul 2008, 09:08

JiM wrote:It's often because of the "equivalent series resistance", which is lower with tantalum. And also better emperature stability, no long-term electrolyte dry-out, etc ...
http://www.low-esr.com/electcompare.html-ssi


Great link! So I learned that tantalums have a solid material where eclectrolytes has a liquid.

Electrolyte
PROS
» Lowest Cost
» Moderately Low Equivalent Series Resistance
» Good Tolerance to Transients
» Open Circuit Failure Mode

Tantalum (Solid)
PROS
» Lowest ESR
» Highest RCR
» Stable Over Temperature
» Long Life, No Wear-Out

Maybe you should explain the tantalum cons, especially the Limited Tolerance to Transients?

» Highest Cost
» Limited Tolerance to Transients
» Short Circuit Failure Mode

And do they really make a difference in stompboxes is the big question?
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Re: Why use tantalum capacitors?

Postby bajaman » 19 Jul 2008, 12:08

Sorry but I cannot explain why, but I do not like tantalum bead capacitors - I do not trust them - just a gut feeling that goes a long way back in time. :scratch:
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Re: Why use tantalum capacitors?

Postby JiM » 19 Jul 2008, 13:21

Here are some possible explanations of "tolerance to transient" :
http://dataweek.co.za/news.aspx?pklNews ... egoryID=46
http://adsabs.harvard.edu/abs/1974STIN...7514030Z
I guess it's mostly about the high current happening in the capacitor as it charges at power-up.

modman wrote:And do they really make a difference in stompboxes is the big question?

Given the frequencies and currents we are dealing with, i think there's no need for costly tantalum caps in stompboxes. You'd want to use these in very-low-voltage, high-current power supplies for demanding digital processors because the ripple of the power supply is proportionnal to the ESR.

For analog audio, nevermind.

In linear power supplies you still can parallel several electrolytic caps, and/or add some small ceramic caps in parallel (one near each IC), to lower ESR and increase transient response. In the signal path, as long as you have a resistor in series you don't care about some milliohms more, it's hidden in tolerances.
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Re: Why use tantalum capacitors?

Postby floris » 20 Jul 2008, 01:41

Because of switching power supplies for computers, low ESR electrolytic caps are being mass produced. These have become available for low prices but are usually of large values starting from 22uF/50V upwards. Check for instance Panasonic FM and FC series.
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Re: Why use tantalum capacitors?

Postby Rocket Roll » 20 Jul 2008, 10:57

http://waltjung.org/PDFs/Picking_Capacitors_1.pdf
http://waltjung.org/PDFs/Picking_Capacitors_2.pdf

Tantalums = low ESR but highest distortion. That distortion makes them very unpopular in modern HiFi designs, but they're "just what the doctor ordered" in effects if you like their "sound" and/ or shoot for "traditional"/ "vintage"/ "characteristic"/ "present". Traditionally they're used in TubeScreamers and in early Rats.
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Capacitor Colour Charts for the different types

Postby modman » 17 Sep 2008, 10:16

I can measure capacitors in my DMM, so I'm not so strong at colour codes. I have a Mullard tropical fish like cap here with the following colours

yellow violet orange white blue

This calculator give the correct result, 47nF. White band is for tolerance, but the lowest band, voltage rating is not given here:

When you use the calculator here:
It returns voltage ratings, but no blue band, and in addition the result is plain wrong.

Even [url=http://en.wikipedia.org/wiki/Electronic_color_code#Resistor.2C_capacitor_and_inductor
]wikipedia is not exhaustive about cap colour codes voltage ratings[/url], which is clearly more important than the actual value, which can always be measured.

This looks like amore exhaustive table better if somebody can explain to me how to translate the dissipation in temp into voltage ratings?

This table for molded Mica caps shows blue is 600V, which seem to be the solution. These 47nF caps have thicker leads than the ones I know are 250V with a red band. In the mica table red = 200V though, so I didn't solve this one... yet.
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Re: Capacitor Colour Charts for the different types

Postby dano » 17 Sep 2008, 18:40

Both of those links don't seem to work for the piel of tropical fish caps I have, I've never found a good online resource for them so I just stick to measuring them with a DMM.
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Re: Capacitor Colour Charts for the different types

Postby Cow4prez » 17 Sep 2008, 19:07

it's like resistors

The codes are as follows:

1st band (furthest away from the leads, i.e.top) black 0, brown 1, red 2, looks familiar ? yes its the same as resistors.
2nd band ditto
3rd band orange X 0.001 uF, yellow X 0.01 uF, green x 0.1 uf
4th band (tolerance) white +/- 10%, black +/- 20%
5th band (working voltages) red 250V dc , yellow 400V dc

There are really only four voltage colors for these capacitors.

Brown=100vdc, red=250vdc,yellow=400vdc and blue=630vdc.

brown 1
black 0
yellow x0.01
white
red

brown 1
green
orange x0.001
white
red
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Capacitor Value Questions

Postby mattpas » 24 Sep 2008, 23:39

If I have something that uses a .2uf cap can I use a .22uf with no problems?
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Re: Film Cap Value Question

Postby analogguru » 25 Sep 2008, 00:07

yes.... since film caps normally have a tolerance of +/- 20 % (except if they are selected and marked as this) the actual value may vary beetween 180n and 260n.

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Re: Film Cap Value Question

Postby mattpas » 25 Sep 2008, 00:17

Thanks,
I thought it would be OK but it is always best to ask.

analogguru wrote:yes.... since film caps normally have a tolerance of +/- 20 % (except if they are selected and marked as this) the actual value may vary beetween 180n and 260n.

analogguru
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Re: Why use tantalum capacitors?

Postby WonderNoise » 25 Sep 2008, 22:06

I think this should be easy to understand, and you can research further to learn more electrical theory of capacitors.

Tantalum is the dielectric (term for non-conductor or insulator) that is used in a tantalum capacitor. Think of the dielectric as the non-conductive material used to store charges in a capacitor. When you exceed the voltage and current ratings for a capacitor, you are overloading it with charge beyond what the dielectric material can handle, causing dielectric breakdown or the failure of the the dielectric, which can result in heat, explosions, or more "silent" problems that are hard to detect and will cause you many headaches.

There are many different capacitor dielectrics for many different applications, because the electrical characteristics of each dielectric vary in ways that can be advantageous for different types of circuits. Some of my products contain tantalum caps, but not every capacitor in those circuits is tantalum. Grab an arbitrary circuit board from any pedal or other consumer electronics product you have and you'll probably be able to find two or more types of capacitors on it. Every single capacitor in a circuit is placed there for a reason, based on carefully calculated values. Because the values and placement of all caps in a circuit is very intentional, the type of capacitor used must also be appropriately matched to the specific task.

Here are a few links to info on capacitors.


The Sound of Capacitors
http://members.aol.com/sbench102/caps.html

Capacitor Calculus:
http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter27/chapter27.html


Comparison Charts:
http://www.analog.com/library/analogDialogue/archives/30-2/chart.html
http://www.rfcafe.com/references/electrical/capacitor_dielectrics.htm

General Info:
http://www.radio-electronics.com/info/data/capacitor/capacitor_types.php

===================================================================

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Re: Why use tantalum capacitors?

Postby floris » 27 Sep 2008, 10:33

In:
http://www.analog.com/library/analogDia ... chart.html
What does "Low DA available" or "Good DA" mean?

Oops... found it here:
http://www.rfcafe.com/references/electr ... ctrics.htm
DA = dielectric absorption

This explained what that means:
http://www.muzique.com/cap_faq.htm
"Dielectric Absorption: An effect where some of the charge stored in a capacitor does not immediately return after discharge, but slowly leaks back at a later time. Some dielectric materials have a kind of sponge effect. Even after you wring the water out of a sponge, it stays wet for some time after. Dielectric Absorption is not a desirable characteristic."
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n00b Question about Capacitors

Postby mantralux » 28 Sep 2008, 23:45

Hello, new guy here.

Just a quick question about capacitors:

Some guides I've read states that I should only get capacitors with a voltage rating of 16-35V for guitar stompboxes. The problem is that I can only find 0,001uF capacitors that has a voltage rating of between 500-630V.

Could I use 630V 0,001uF capacitors, what difference does it make?

Please explain as if I'm 5 years old. 8)
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Re: Why use tantalum capacitors?

Postby modman » 12 Oct 2008, 20:28

from Ampage forum wrote:Tantalums are good substitutes for Electroilytics but not for mylar, polypropelyne, or polystyrene film caps, or foil caps for that matter. Tantalums are very poor capacitors in terms of Equivalent Series Resistance (ESR) and Dielectric Factor (DF) qualities. The only redeeming quality of tantalums is their low temperature coefficient. In other words, they don't change value much as they heat up.

Film caps on the other hand have lower ESR and DF values than tantalum caps making them better for audio. In general, the capacitor 'quaility' hierarchy is as follows:

1. Electrolytic *** Lowest Quality ***

2. Tantalums

3. Paper (1950- 60's. These are no longer made)

4. Paper Saturated with Oil (i.e. Vitamin Q style)

5. Mylar (i.e., Polyethylene)

6. Polypropylene

7. Polystyrene

8. Teflon *** Highest Quality ***

In general, you get what you pay for with higher quality caps costing more. Although some poor quality caps, like vitamin Q's, will cost you an arm and a leg because they are built to last forever rather than for sound quaility.

A quick discussion of DF is needed to fully understand why certain capacitors sound better than others. In essence, DF is a measure of a capacitors ability to discharge quickly. The faster a capacitor can discharge, the more accurately it can reproduce music. For, example, polypropylene capacitors sound alot more 'accurate' than mylar capacitors even though both are film caps. They also tend to reproduce high frequencies more accurately and therefore are sometimes perceived to sound a bit brighter.

There is one caveat to a cap having a good DF rating. Vintage guitar amps sound vintage because they used relatively poor quality paper capacitors in their manufacture. In other words, the poor DF of these caps was part of the amplifier's tone. A poor DF cap tends to smear the sound a bit making it less accurate but darker and warmer sounding which, though not desireable for audiophile applications, is a desirable quaility for some guitar amps.

This is not to say that a poor DF rated cap is what you want for your guitar amp. High end amps made today like Matchless or Trainwreck use polypropylene and polystyrene caps deliberately to take advantage of their more accurate sound. More conventional amps, like Marshall and Fender on the other hand, almost universally use electrolytics in their power supply and cheap mylar caps in their audio circuitry. There is a very good reason why a Matchless costs more than a Marshall.


Here's a few final comments on capacitor types:

1. Paper capacitors were used in the 1950-60's because they were cheap to manufacture. Unfortunately, they tend to go bad over time causing constant problems among vintage amp collectors. If you really want to retain the amp's vintage sound without going through the headache of constant repair, replace the original paper caps in a vintage amp with Paper in Oil caps which are the closet things that are still manufactured today. Paper in Oil caps such as Vitamin Q caps have an added benefit in that they are known to last forever and usually never needing replacing.

2. Different capacitor types have tremendous variations in their size for a given amount of capacitance. This is one reason why you don't see Polystyrene caps used alot even though they sound superior.

3. Internal construction of the cap also makes a big diffeence in sound. If a film cap is constructed coaxially, like MIT Multi-caps for example, the cap will have a more accurate sound then a conventionally constructed capacitor.

4. Film caps are always inferior to Foil caps in terms of sound for a given dielectric. A film cap is manufactured by spraying a very thin coating of metal such as aluminum on the dielectric material such as mylar. This technique is used because it saves on cost of materials as well as time and labor. Foil caps on the other hand use thin sheets of metal for the conductors within the capactors. Because of higher cost, you rarely see foil caps used in guitar amps eventhough they are greatly superior.

I hope this information helps somebody.


source: http://archive.ampage.org/threads/1/ope ... ILM-1.html
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Re: n00b Question about Capacitors

Postby IvIark » 17 Oct 2008, 11:36

The 630V will work but will be physically bigger than it needs to be. You shouldn't have any problem sourcing 0.001uF capacitors (or 1nF or 1000pF - it's all the same). What about this? Or if you're in Europe, this?
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Re: n00b Question about Capacitors

Postby bajaman » 17 Oct 2008, 11:54

one rule: the higher the voltage rating the better the sound will be - sometimes subtle, other times dramatic.
Of course the higher voltage capacitors are physically larger, so either use a bigger enclosure or smaller lower voltage capacitors. Do not use lower voltage rating than your power supply voltage though, unless you like explosions and changing fuses etc.
polystyrene and silver mica are the smoothest sounding and most linear in there transfer characteristics. They also have lower effective serial resistance - we do not want a capacitor that works like a resistor at audio frequencies.
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Re: Capacitor FAQ

Postby modman » 27 Oct 2008, 17:04

I merged some separate capacitor related FAQ threads into one, assuming the posts would retain all their original titles. Now this is crazy: some did, some didn't.

I will see what I can do. If nothing else helps, I will put the titles back manually.

sorry guys
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