Capacitors Made Easy The Hackaday Way | Hackaday

If you build electronic circuits on a regular basis, you may use capacitors multiple times. They are standard components used with resistors, and their resistance values ​​can be proposed without consideration. We use them for power smoothing and decoupling, DC blocking, timing circuits and more applications.

The capacitor is not a simple spot, it has two wires and two parameters: working voltage and capacitance. Various capacitor technologies and materials have different characteristics. Although almost any capacitor with the correct value can accomplish the task in most cases, you will find that understanding these different devices can help you do things that not only accomplish the task, but also do the best. For example, if you have to pursue thermal stability issues or find these additional dB noise sources, you would be very grateful.

It is best to start with the basics and describe the capacitance from the basic principles before studying the actual capacitor. The ideal capacitor consists of two conductive plates separated by a non-conductive dielectric. Charge will accumulate on the board, but due to the insulating properties of the dielectric, they cannot flow between them. Therefore, the capacitor can store charge.

Capacitance is in farads: a farad capacitor holds a voltage of one volt while holding a coulomb charge. A farad, like many SI units, is impractical in size, so outside the narrow domain of supercapacitors (outside the scope of this article), you are more likely to encounter micro, nano, or picofarads. You can use a formula that may be worthwhile to derive its capacitance from the size and dielectric properties of any given capacitor

. Unless you are studying for a high school physics exam, you don’t need to remember it, but it hides an important point. The capacitance is proportional to the dielectric constant

The increase in the number of dielectric materials used has led to various commercially available capacitors using different dielectric materials to achieve a higher capacitance range or better voltage handling characteristics.

There are obstacles to the use of dielectric materials in capacitors, and the ideal properties of dielectrics also bring many unpleasant side effects. All capacitors in the real world have internal parasitic resistance and inductance. Although small, they sometimes affect the operation of the capacitor. The dielectric constant changes with temperature or voltage, piezoelectricity or noise. Different types of capacitors may have shocking failure modes, and even amazing prices. Therefore, we have entered the main part of this section. In this section, we will take you to understand some types of capacitors you may encounter and list their various characteristics, including good and bad. We will not claim to cover all possible capacitor technologies, but we will introduce common capacitor technologies and check any subtypes you might find.

An aluminum electrolytic capacitor uses an anodic oxide layer on an aluminum plate as a dielectric, and the electrochemical battery electrolyte that forms it is used as another aluminum electrolytic capacitor. Because they are electrochemical cells, they are polarized, in other words, any DC potential passing through them must always be in the same direction as the anode plate (!) or the positive terminal as the anodized plate.

The pole plates of practical electrolytic capacitors in the form of aluminum foil sandwich plates are rolled into a cylinder and contained in an aluminum can. Their quoted working voltage depends on the depth of the anodized layer.

Electrolytic capacitors have the largest capacitance you will encounter in normal use, ranging from 0.1 to thousands of µF. Due to the tightly wound electrochemical cells, they have a high equivalent series inductance, so they are not suitable for use at high frequencies. In general, you will find them useful for power smoothing and decoupling and audio coupling.

Tantalum electrolytic capacitors are in the form of sintered tantalum anodes, which have a very high surface area, on which a thick oxide layer is grown, and a manganese dioxide electrolyte is applied on it as the cathode. The combination of high surface area and the dielectric properties of tantalum oxide dielectric means that the capacitance per unit volume of tantalum capacitors is very high, so tantalum capacitors are much smaller than aluminum electrolytic capacitors with the same capacitance. Like aluminum electrolysis, tantalum capacitors must also be polarized, and the DC potential at both ends must always be in the same direction.

The value of tantalum capacitor is about 0.1 to hundreds of µF. Compared with similar aluminum products, their leakage resistance and equivalent series resistance are much lower, so you can find them in test and measurement, high-end audio, and other advantageous applications.

Tantalum capacitors have a failure mode that requires attention. They are known to catch fire. Amorphous tantalum oxide is a good dielectric, while the crystalline form of tantalum oxide is a good conductor. Misoperation of tantalum capacitors by applying excessive surge currents to tantalum capacitors may cause the dielectric to change from one form to another, resulting in a substantial increase in the current flowing through the capacitor. Fortunately, not all news is bad news. Their reputation in the fire comes from earlier tantalum capacitors, and improved manufacturing technology has delivered more reliable products.

There are entire series of capacitors that use polymer films as dielectrics, which are sandwiched between coiled or staggered layers of metal foil, or have a metalized layer deposited on the surface. The rated voltage of these capacitors can be around 1000V, but they are not suitable for large-capacity capacitors. You will find that their capacitance ranges from about 100pF to single-amplitude µF. Each different polymer dielectric used has its own advantages and disadvantages, but the equivalent series capacitance and inductance of the entire capacitor series are lower than the electrolytic capacitors discussed so far. Therefore, you will see their use in higher frequency applications, as well as power supply decoupling in electrical noise environments and general applications.

Capacitors are used in circuits that require good temperature and frequency stability. You will also find that they are used in power supply suppression and other power circuits, especially for rated versions for high-voltage AC use.

Capacitors do not have the temperature and frequency characteristics of polypropylene, but they are inexpensive and can withstand the high temperatures of SMD soldering. Therefore, you will find them used as general purpose capacitors in non-critical applications.

Capacitors still do not have stable temperature and frequency characteristics, but they can withstand much higher temperature and voltage than polyester.

The capacitor has all the temperature and frequency stability of polypropylene and can withstand high temperatures.

You may also encounter

with

Capacitors in old equipment, but these two dielectrics are not commonly used today.

Ceramic capacitors have a long history, and you can find them in devices that span decades from today to the beginning of the last century. Earlier ceramic capacitors were single-layer ceramics plated with metal on either side, while recent examples also include multi-layer designs in which alternating layers of metal and ceramic are constructed to form a set of staggered plates. Depending on the dielectric used, the capacitance ranges from 1pf to tens of µF, and the voltage is kilovolts. You will find single-layer ceramic discs and multilayer ceramic surface mount packages used in a variety of small capacitor applications in all areas of electronic products.

When looking at ceramic capacitors, it is best to consider them in terms of the ceramic dielectric used, because they derive their performance from these capacitors. Ceramic dielectric classification

It is these codes where we will quote the most common codes.

The dielectric has the best capacitance stability in terms of temperature, frequency and voltage. You will find C0G capacitors for resonant high frequency and other high performance circuits.

The dielectric does not have the temperature or voltage characteristics of COG, so it can be used in less important applications. Generally, you will find them for decoupling and general-purpose applications.

The dielectric has a higher capacitance than X7R, but has poor temperature characteristics and a lower maximum voltage. Like X7R, you will find them in general purpose and decoupling circuits.

Since ceramics are also generally piezoelectric, some ceramic capacitors also exhibit micro-sounding. If you are working under high voltage and audible frequencies, such as in a tube amplifier or electrostatic environment, you may sometimes hear this effect because the capacitor may "sing". If you use piezoelectric capacitors to provide frequency stability, you may find that they are modulated by environmental vibrations.

As mentioned earlier, this article does not attempt to cover all capacitor technologies. A quick look at the electronic consumables catalog will show you several technologies not mentioned here, and many others are outdated or have a small niche that you rarely see them. Instead, what we want to achieve is to make some of the common types you might see mysterious and help you make choices when you make your own designs. If we arouse your appetite for more component loss, maybe we can get your attention

.

It doesn't matter, use capacitors that require almost zero inductance in the microwave area.

How about im head capacitors?

Or PCB capacitor?

Variable PCB capacitors?

Yeah, I know. "This article does not attempt to cover all capacitor technologies." I just want to point out that those will be interesting because you can make your own!

Lol, no, they are useful links, not sure if his book lists other uses for large capacitors...

Thank you for linking with variable PCB capacitors. This will come in handy.

I like those links. thanks for sharing.

No mention of the capacitor disaster:

Jenny forgot to mention that Magic Blue Smoke was among them.

No, that's fast magic blue smoke. It escapes faster than ordinary blue smoke.

Thank you for your information! Don't know at all (always think what I see is related to the wrong temperature specification)​​!

Particularly worth reading is the root cause of this huge problem: the perfect example of "good, bad, ugly"-capacitor companies in Japan, China, and Taiwan. Maybe this is the reason why my 2006 iMac power unit failed.

charming! I know this question, but I don't know where there is such a comprehensive understanding. Thank you for contacting us.

The trap for young players is the forced pressure reduction of tantalum... The issue is not often mentioned until the part fails and the manufacturer points you to the white paper.

Other curious traps:

– The capacitance of ceramic capacitors varies greatly with the applied voltage. If a voltage close to 10V is applied, a 100nF rated 10V capacitor may only have a 10nF capacitor.

– Class 2 (not COG NPO) ceramic capacitors decline over time and recover after re-soldering. This is a non-linear thing, which is very eye-catching for newly produced or newly welded caps.

– When a new aluminum electrolytic cover or no voltage is applied for about 6 months, the leakage of the aluminum electrolytic cover is 10 times. They need a few minutes to "reform".

– The leakage of aluminum electrolytic capacitors varies with voltage in a non-linear manner, so general electrolytic capacitors usually self-discharge to about 30% of the rated voltage quickly, and then will not drop below 20% of the rated voltage for months or even years.

-The aluminum electrolytic cover will change proportionally with temperature, and all other factors will change slightly. A good rule of thumb is that for every 10°C increase in operating temperature, it will decrease by half an hour. vice versa. So, if you run 1000 hours at 100C rated capacity at 40C, it will last 64,000 hours.

–Specifies the capacitance value of Class 2 (X7R, Y5U) ceramic capacitors and the tolerance at +25°C. In most cases, the peak is not far away (maybe 20°C). This means that when you stay away from room temperature, the capacitance usually drops. It does not increase one method, nor does it reduce another.

Regarding the first point of the list, the change in capacitance with voltage is only applicable to Type 2 dielectrics. It also particularly affects smaller external dimensions, but does not change much with the rated voltage. This Maxim application note is very interesting:

The C0G/NP0 dielectric is basically flat. But this is something that many people will miss, because most of the ceramic capacitor datasheets I have seen don't even mention it, and there is no e-book I have read, nor is this article.

Same Here. I didn't fully realize the characteristics of DC bias until a few years ago, when a sales representative of a supplier who had just released a series of new bottle caps with "low DC bias function" came to our company to advertise. Makes me wonder what else is under the carpet.

How repeatable/reliable is the effect?

Can you reliably build a VCO by applying different bias voltages?

There are not only type 1 and type 2 ceramic capacitors. A better statement may be that the Class 1 capacitors were not significantly affected.

correct.

Then there are temperature-compensated ceramic capacitors. They are not common in today's cheap crystal oscillators and digital synthesis frequencies, but you will find them in older equipment, and perhaps in some older electronics stores. If you use them by mistake when you expect the temperature, you will feel unhappy. They are usually available in N750 and N1500, if memory is available, P150 and N2200 can also be used. They are used to stabilize the temperature of RF oscillators and filters. The inductance of the inductor will increase with the increase of temperature; therefore, the use of capacitors with a negative temperature coefficient (for N750 type capacitors, 750 parts per million degrees Celsius) will be used to maintain the resonance frequency roughly with temperature changes Constant. They will be used in parallel or in series with NP0 (C0G) capacitors to produce a net temperature coefficient that offsets the net temperature coefficient of the inductor. The use of temperature compensation capacitors can produce surprisingly stable and easy-to-tune tens of megahertz oscillators.

If you can find it, does ETI remember? John Lindsey Hood has written a series of wonderful articles called "True Ingredients." It thinks in the late 1980s. It's worth trying. I have a series somewhere.

John Linsley Hood

I cannot find many online copies.

Thanks for that. If there is enough interest, and I can sort out copywrite, I can scan my article. In 1985, memory was still OK. I know it will be there.

Please I am very interested. When reading in-depth articles about electronics in the 1980s, I got the golden age of electronic atmosphere.

There are copies of old 1950s popular mechanics everywhere on the Internet, and I really like the copies I have. The big business at the time was selling mail-order courses to train people to become TV technicians. The college competition provides more and more things to build themselves, with meters and complete TVs with various screen sizes.

I recently started as an electrical test engineer and started using "professional" parts. The main difference lies in designing and ordering parts for each project. Out of hobby, I picked up a box of old capacitors and pulled it out until there were (close to) matches. Anyway, in my project, I found 10uF (50V) ceramic capacitors in the 1206 case, and I used them to replace the electrolytic capacitors in circuits such as MAX232. In the case of 1206, they rose to 220uF (2,5V)...

That's great!

Now, understand the DC bias effect of each ceramic capacitor whose dielectric is not NP0/COG.

Pro Tip 1:

Your 10uF ceramic capacitor is not 10uF.

Although this is much more detailed than the article, please don't forget to use Mica capacitors to prototype the semiconductor buffer in the switching power supply.

Pro Tip 2:

If you work in engineering and want to keep that job, please visit the manufacturer's website to calculate the life of aluminum electrolytic capacitors in your application. This is especially important in power supply, high temperature, high rms ripple current or high voltage applications.

Pro Tip 2a: Press the ctrl key and click to display the root mean square value of the waveform in LTSpice.

Thanks for the tips. The capacitor rating is 1v DC. The size of the 1206 is better than the smaller size, which is the main reason why the 1206 is selected for low output and easy manual welding (expensive labor).

For me, the most important point mentioned earlier is the effect of temperature on the life expectancy of electrolytic capacitors. In my experience, due to other reasons beyond the rated value, the failure of electronic equipment is almost always caused by the failure of the electrolytic capacitor. If you want to continue using it for 10 years, it is best to keep any electrolyte cool. Keep them away from CPUs and similar chips, etc. Your device may be used for several years.

Don't forget that flux capacitors usually require very high voltages to work.

Rated working time is -30 years

Please don't believe it until you see the data sheet and receive a sample of my product from Rubycon.

I miss capacitors-they can actually condense electricity. Electrical condensate is indeed powerful. You don't want to get anything.

But what can capacitors do? Will they be capacitive? Will they promote capacitation? Do you want to use those words in the sentence?

Abandoning Alessandro, they have not been called condensers for 60 years.

I have been working on motorcycles in the late 1970s, and all service documents refer to condensers wired as required. This means that only 37 years ago, it was still a generic term (at least in this app).

Condenser is a general term in ignition systems and has long been obsolete in other applications. I am sure that the replacement part is still called a condenser.

In Romania, they still call it a "condenser". You can imagine the expressions of an ancient university teacher when students say "capacitor" after reading an English document.

Personally, as long as both sides of the conversation understand what is being said, I don't care how to call them.

In Dutch, the word capacitor is still "capacitor"

And in the French "condenser"

In the automotive industry, they are still called condensers.

I am 60 years old, does that mean I am no longer useful?

If you touch the terminals of the larger terminals, they may make you incapacitated.

The term capacitor was first used in the 1920s. The Navy seems to be an early adopter. The condenser gradually disappeared until it disappeared (almost) in the 1960s. Some people think that capacitors are closer to the resistors and inductors already used, but who knows.

When I was working for Tek in the late 1970s, they discovered that for a particular case size, never use the largest capacitor available. Always go to the next larger box. I can’t start telling you how many caps were removed and replaced with larger cases to improve reliability.

Likewise, not all electrolytic capacitors are the same. Replace a low ESR capacitor with an equivalent value, instead of a low ESR capacitor, you will see the inside of the capacitor.

Mica caps can also be used. See that the CM04 cover can be unsoldered from the RF breadboard. When they moved to CM06, they got warmer, but not hot enough to melt the solder.

For the same capacitance value, the next larger case size has a larger surface area.

Calculate the key value of electrolytic capacitor life.

Unless absolutely necessary, avoid using tantalum capacitors, and then try to check your supplier. The tan tantalite industry has become severely corrupt, causing catastrophic wars and human rights issues.

If we follow this policy globally, none of us will buy anything with rare earth magnets in it, because +90% of the market is controlled by a totalitarian regime with a very bad human rights record.

So, Peter, if there is a hard drive in the computer, please return the computer. Only buy SSD from now on? What about everything else with a compact motor equipped with rare earth magnets?

Yes, if you haven't solved the problem, then I hate an evil person more than a proud evil person. He implies that they are not evil, and everyone else is evil.

Look, when I read the review, I just saw someone trying to light up something, something most people don't know. He did not say "Don't use tantalum capacitors", "If you use them, it would be terrible." He just kindly asked, "Please avoid using tantalum capacitors." All other statements in his comment are statements of fact. You can still use whatever you want in your design. No one accuses you of being evil.

Maybe you just reacted to the previous discussion about tantalum that you participated in before, and the commenter was more demanding than Peter.

Lol, what a hot load. As I implied, hypocrisy.

These days, can you even buy phones that guarantee conflicts and free human rights violations?

no, you can not. Many people do know this, and most of the people in this group really don't care. I care, but boycotting does not stop this practice. The people involved just adapted without actually reducing the harm to the innocent.

If you have questions about the behavior of immoral people, please disband these people, because there is no other way to stop them. Boycott is a very blunt tool, which usually causes a lot of incidental economic losses, and even more innocent people. Bring harm.

Do you honestly believe that you are so wise that you can recommend any form of boycott and can predict the true result? Why not just ask people to donate to NGOs that help those in need to resist harm? Isn't this more destructive, or more sensible?

Sorry if you don't like my opinion, but at least I can prove it strongly!

Regarding the phone, there is currently a project, although I do not claim to own it. As you said, there is no way to guarantee that they will do what they say:

.

I think you are confused-I have never tried to talk about tantalum capacitors since the beginning. Please read my comment again. I just want to point out that Peter is not accusing you of evil. He did not ask for any moral requirements. Yes, he advises you not to use tantalum capacitors, because that is his belief. But does he think he is "better than you" just because he doesn't use tantalum capacitors? I do not think so. This is the point I want to make. Is it hard to believe that this might be ignorance? In this case, the reply you just gave me will be deeply valued by him.

Most of the arguments you put forward in this response sound good, and if you put them in the original comment, I won’t have any questions about it. There is no problem with my opinion. I just want to use "attack your emotional foundation". Yes, if you haven’t solved this problem, the only evil people I don’t like are evil people. He suggested that they are not evil, others Everyone is. "This is not the right choice. In general, your first comment is indeed...not good. Has it become so difficult online?

Like I said, how hot the air is, you can't verify any of them. In any case, what right do you have to regulate the Internet, and that is that, in the eyes of some people, arrogance is just as offensive as in my comments. It looks like you are a self-righteous hypocrite like "Peter". Even if you just don’t dare to question them, your thoughts about “good” always boil down to people who “fit your dogma”.

>Sorry if you don't like my opinion, but at least I can prove it strongly!

This is not your opinion, but your attitude towards the opinions of others.

I'm sorry, Dan. What you are doing is "If we can't fix all the problems at once, then make those who try to fix certain problems proud". I must stand by Peter and Droif. Always pay attention to the problem, choose some problems and try to solve them. Stay vigilant and don't try to solve it (others may try).

Engineers should work like this.

You can choose not to use them in your design.

Yes, you can do what you want to do according to your own design, but don't deceive yourself, because you may actually be hurting others. If you can use them in your design and save money, you can donate the difference in profits to charity (if you really care). Or do you think bad people are better at doing good than bad people? Take a moment to think carefully.

No, I will not.

However, whenever I do not choose a tantalum cap, I will be happy for your rant.

This is not a rant, just a tantrum!

what! Okay, thank you.

I made it. Usually, because they can be used as electronic igniters well.

Obviously, Kemet "guarantees" that the tantalum in its products is conflict-free.

They provided a report listing the sources of tantalum (and other minerals): China, the United States, Thailand, Germany, Kazakhstan, Austria, and Japan. This is required by the US Dodd-Frank Conflict Minerals Regulations-does anyone here know more about this/bell?

AVX and:

All your stuff comes from China,

All your things are contaminated. Cheer up and stop deceiving yourself. The market is like a water container. You take water from one part, but you still increase the demand for all other parts. There is also the fact that once they enter a huge resource base like China, you really cannot track the material. You just want to feel special.

Would have liked to hear more about self-healing polymer capacitors. As far as I know, they are usually used as X or Y filter components in mains voltage applications, but maybe there are other interesting applications where self-healing capacitors are used? How does self-repair work?

Good article, thank you!

Errata:

I think tantalum has a lower leakage than aluminum electrolyte and therefore has a higher leakage resistance.

A typo, not a complete error :) – Every different polymer dielectric used has its own characteristics, has its advantages and disadvantages, but compared to the electrolytic capacitors we discussed, the entire capacitor series has an equivalent series* *Capacitance** and inductance are both low. to date.

Ok

The real conflict with tantalum bottle caps is their failure mode.

Find the safe derating of tantalum capacitors. They are ridiculous because they cannot be used in all applications except for the most absolutely necessary applications (very low ESR and high capacitance).

Safety is the reason to avoid them.

If your voltage converter happens to be 500w, what capacitor would you use?

:)

Some good things about iequalscdvdt.com

"Although not all news is bad news, their reputation in the fire comes from earlier tantalum capacitors, and improved manufacturing technology has provided more reliable products."

Do not. You may be confused by the existence of multiple "tantalum" caps.

. The sturdy tantalum cover has a fire failure mode. This is not surprising: the electrolyte is MnO2, so you have many easy-to-access oxygen tanks, and they will flourish. However, the sturdy tantalum capacitor caps can also be self-repairing and can withstand less pressure, so under the right conditions, they are very reliable and can be stable for a long time (no service life). However, they are still not inherently safe. The sturdy tantalum caps will not burn because of short-term failure, but because they "ignite" and burn.

However, the tantalum polymer cap does not have an ignition failure mode because the electrolyte is not MnO2, but a polymer. They also have lower ESR, but lower long-term reliability (due to polymer degradation). However, they will not catch fire on their own. However, they do experience short-circuit faults, so they can still take out systems that are not limited by current.

Niobium oxide caps are basically solid tantalum caps without an ignition device (long-term stable), so you would consider them ideal-but they are also expensive and uncommon.

For young players, the trap of solid polymer aluminum capacitors and electrolytic aluminum capacitors:

"Because the polymer is a solid, it also has a longer service life, and does not follow the classic Arrhenius formula. The temperature will not double every 10°C, and every 20°C drop in temperature, the life will be 10 times longer."

Translation: Every 20°C increase in temperature will shorten the life span by 10 times.

It's a bit different, isn't it?

A small mistake:

The equivalent series capacitance and inductance of the entire capacitor series are low

Should be "equivalent series

(ESR)"

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