In the realm of passive components, capacitors are second only to resistors in ubiquity. They are everywhere, in almost every electronic device you will ever come across. So it’s no surprise that capacitors are an integral part of audio circuits in general, and guitar effects specifically.
What makes capacitors so important? Well, they can be used to perform some very important functions:
- DC Blocking:Capacitors pass alternating current (AC), but block direct current (DC)
- Coupling: Capacitors are used in between various stages in audio circuits
- Filtering: Capacitors are key elements of filters, such as a tone control
- Smoothing: Capacitors are used to smooth out ripples and noise in power supplies
- Timing: Capacitors are used to set the timing of circuits such as low frequency oscillators
- Storing: Large value capacitors are used to store up energy. For example, the flash of a camera typically uses a capacitor to store and quickly discharge amount of power
Units of Measure
As with all passive components, you need to have a basic understanding of units of measure when working with capacitors. Capacitance is measured in Farads, named after English physicist Michael Faraday. A value of 1 Farad is actually quite high, so we use sub measures as follows:
|μF||micro||1,000,000μF = 1F|
|n||nano||1,000nF = 1μF|
|p||pico||1,000pF = 1nF|
If you are like me, the concept of base 10 arithmetic is wildly advanced and causes your head to hurt. So I invariably turn to the awesome online and downloadable calculators from http://www.electronics2000.co.uk for doing unit conversions.
Although capacitors come in an almost bewildering array of types and sizes, no need to worry. The majority of capacitors in guitar effect designs fall into three types:
- Electrolytic: Usually for large capacitance values, typically 1μF and above. These are usually polarized, meaning there are positive and negative leads.
- Film: The most commonly used types, typically in the range of 1nF to 999nF. These are non-polarized and can go in either way.
- Ceramic: Used for smaller values, typically from 10pF to 999pF. As with Film capacitors, these are non-polarized.
With these basic types in minds, let’s learn a bit more about each.
One of the most common questions about choosing capacitors is voltage rating. Different capacitors are rated for different voltage ranges. The best rule of thumb is to choose a capacitor with a voltage rating that is at least twice the operating voltage of your circuit. So if you are building a circuit that runs of 9 volts, choose capacitors with ratings of at least 16 volts.
Electrolytic capacitors are visually distinguished by their ‘can’ form factor. They are commonly used in power supply filtering and decoupling applications. They are usually polarized which means that they have a positive side and a negative side. (See “Non-Polarized Electrolytics”below).
Electrolytic capacitors come in several physical configurations:
The polarity of the electrolytic capacitor is almost always indicated by a printed band. Additionally, the positive lead is usually longer.
When working with electrolytic capacitors, here are a few things to keep in mind:
- Polarity: Most electrolytic capacitors are polarized. Hook them up the wrong way and at best, you’ll block the signal passing through. At worst (for higher voltage applications) they’ll explode.
- Getting Shocked and Possibly Dying: This is not usually a concern for low-voltage stompbox applications, but for high-voltage circuits, especially tube amplifiers, big electros can hold a charge for quite a while. Before you open up anything that plugs into the wall, google capacitor discharging and approach with caution. See ;Capacitor Fires and Explosions” below.
- Radial vs. Axial:To maximize the real estate on a PCB, you’ll almost always want to use radial leads. When you order caps, get the radial ones. If you order Axial by mistake, it isn’t hard to bend the leads so as to mount them in a radial, upright configuration.
- Non-Polarized Electrolytics: To further confound you, electrolytics are made in non-polarized versions. These are rarely used. The only place I’ve seen them is on either side of the first opamp stage in the Tube Screamer.
Ceramic caps are typically used for lower capacitance jobs. Values are usually in the picofarad to low nanofarad range. They are ugly looking, and that is about as technical as I’ll get on the whole ceramic vs. film caps debate.
Most folks cannot discern an audible difference between the two types in common stompbox use, so you’ll have to try for yourself. A good rule of thumb is to remember that from an electrical engineering standpoint, film capacitors are generally preferred over ceramics in audio path applications. Ceramics are non-polarized and usually supplied in the radial lead configuration.
The Great Tantalum Debate
Tantalum capacitors were popular in the eighties in stompbox designs like the Ibanez Tube Screamer and various MXR and DOD designs. The primary benefit of tantalums is that they offer a higher range of capacitance values in package that is physically smaller than electrolytics.
Like electrolytics, they are polarized so you’ll want to get the direction right. Tantalums are *very* susceptible to polarity inversion. In other words, if you hook one up backwards you might as well throw it away–there is a good chance it is cooked.
Do they sound better? Do they sound different? The answer is a definitive yes. No wait, that’s a definitive no. There are many opinions about tants, so I really cannot offer you anything definitive on this subject. I can however, share some of the feedback and comments I’ve heard and read.
- Replace place all electrolytic caps in the signal path with tantalums for a smoother sound.
Some folks hear more “grit” and treble with tantalums. Some hear a smoother sound.
- Replace the .022 tantalum in your tube screamers with a poly film part for better sound, others claim the original part is integral to the true tube screamer sound.
- Some folks claim tantalums are not as reliable as electrolytics, but this may be mostly due to older composition and packaging types uses in decades past.
As always, your mileage will vary. But this is one of the most wonderful areas of stompbox design–there are so many variations, we’ll probably never get bored. Try the variations yourself until you find your ideal sound.
Capacitors on the Fringe
There are various esoteric or rare capacitor types that pop up from time to time.
Tropical Fish Caps
These are vintage poly film capacitors that use color codes to denote the capacitance value. Very rare nowadays and expensive too. Some builders like to use them in vintage circuits,especially wah pedals.
The Wima Audio Black Box Audio Cap
Rare, elusive and really expensive. I don’t have much info on these, but some audiophile people swear by them.
Most tantalum caps are of the dry-slug variety. This means that they are composed of dry tantalum powder. Wet-slug tantalums on the other hand use gelled sulfuric acid. For more mojo, I wonder if wet-slug tantalums would be worth trying. Although they are typically used for high temperature and voltage applications, one has to wonder…
In the world of DIY audiophile building, a great emphasis is often placed on capacitor performance. As a result, there are a number of manufacturers of high-end (and expensive) capacitors. I’ll leave the subjective vs. objective argument to the reader. But it does make sense to point out that guitar effects, especially in stompbox format, are not designed to be audiophile devices.
Which Type Should I Choose?
As with all component types, there are pros and cons for each type. In general, the choice of capacitor type will be made for you, either by the author of the schematic you are using, or by the simple factor of capacitance value. In other words, the schematic will specify electrolytic or film by the symbol used. That makes the choice easy.
But what about when a specific type is not specified, only the value is shown? In general, you look at the value specified, and choose the type appropriate for that value. Other factors may influence your choice of capacitor type, particularly in audio circuits. So I’ve include benefits and drawbacks of each type.
|Capacitor Type||Typical Value Range||Schematic Symbol||Benefitts||Drawbacks|
|Higher capacitance values in smaller packages, Reasonable price||Leakage is higher than most types, service life: Electros typically don’t last near as long as other types. This is typically why tube amps need to be re-capped after a number of years. Tolerance is not great: most passive electronic components have a tolerance rating which denotes how close to the part is to the actual printed value. Tolerance for electrolytics is abysmal, in the 20-40% range, but for stompbox applications, this doesn’t matter.|
|Film||1nF – 999nF||⎯||⎯̇||Low leakage and they last a long time||Larger values are inordinately physically large|
|Ceramic||1pF – 999pF||⎯||⎯||Inexpensive||Film caps are usually preferred to ceramic caps where audio performance is a key design factor|
Capacitors on Schematics
Here’s what capacitors look like on schematics:
What about Variable Capacitors?
One of the first questions I had when I started building stompboxes was “I have variable resistors (potentiometers) all over the place. Why don’t I have variable capacitors?” The answer is that they are limited to a very small capacitance and are quite expensive too. As such, they are not practical for stompbox usage.
Here’s a trick to simulate a variable capacitor, especially useful for tone control applications. Attach two different capacitor values to a potentiometer–moving the wiper then sends more or less of the signal to one of the caps thereby changing the frequency response.
Capacitor Fires and Explosions
Like other components, capacitors can explode, burn, and/or stink when they are voltage-abused. Here are some fun fire and explosion pictures. Note that many capacitors were harmed during these experiments.
Some builders have intimated that tantalum capacitors smell the worst when on fire. This is a very useful piece of engineering knowledge to have.
The Application of Capacitors in Stompboxes
So now we are familiar with the basics of capacitors, how can we use them in stompboxes? In a surprisingly large number of ways actually.
Power Supply Filtering
In the context of stompboxes, power supply is a low voltage (usually 1.5-18 volts) direct current. The battery is a pretty ideal power source for stompboxes. As long as the battery isn’t dying or depleted, it doesn’t fluctuate wildly or introduce DC ripple into the equation. So if you are running solely on battery power, you really don’t need to worry much about filtering.
Power supplies, like the ubiquitous unregulated black wall warts on the other hand aren’t so ideal. If you are sure that your stompbox design will only ever see external voltage as supplied by a nicely regulated and filtered AC adaptor, then you don’t need to design in filtering. But in the real world, such assurances are not available. You have to assume that at some point you (or the person you build stompboxes for) will plug in a cheap nasty Szechuan special and noise and nastiness will result.
Of course, it is interesting to note that many stompbox schematics will include no filtering at all, and for the majority of uses, that is actually ok. Filtering really becomes an issue when your circuit is presented with a crappy power supply or fluctuating “crazy Ivan” mains voltage.
A wall wart uses a transformer to step down the mains voltage to a pedal friendly 9-11 volts or so (for a 9v adaptor) and then converts AC into DC using a 4-diode bridge rectifier. The rectifier flips all the waveform swings of the AC voltage but still results in some “ripple” in the DC waveform. Ripple equates to noise in your circuit. The simplest way to get rid of this ripple is to tack a largish-value electrolytic cap from the power supply to ground to smooth things out. For most stompbox designs, this works just great. Let’s look at an example.
Here we simply add a 100uf polarized electrolytic from the power supply line to ground to reduce ripple:
Finally, there is an additional electrolytic on the bias voltage (C3) which smoothes out the bias supply.
A parting note on caps in power supplies. For amplifier circuits, you’ll see big electrolytic cans in the power supply section that you don’t see in stompboxes. These act as “reservoirs” of current to handle short spikes in power demands from the amplifier and to smooth out the available pool of current.
The Input and Output Caps
Almost every stompbox design has these two caps. As we talk about these, keep in mind the following schematic of the Electro Harmonix LPB booster (I’m using this one because it has input and output caps and is about as simple a circuit as you can find.)
The input cap (C1), if you haven’t already guessed, is attached at or very near the input. The purpose of the input cap is to form a high-pass filter, in conjunction with a resistor (here the R2 part). It also acts to stabilize the rest of the circuit from the input which is usually a guitar, bouzouki, or another pedal. The key point here is:
The value of the input cap directly controls any frequency attenuation that happens before the signal hits the main effect circuitry.
Now on to the output cap. In our schematic above, that’s the C2 value. The output cap serves two purposes. First, like the input cap, it can serve as part of an RC network to attenuate or pass certain frequencies. If you want the full frequency range, a value from 100nf to 1uf can be used. The output cap also serves to remove any direct current from the signal. Remember that our stompbox designs almost all run on direct current–we want to be sure none if it escapes from the output jack, so an electrolytic cap will do the job nicely.
|Input and Output Capacitor Values from Various Classic Stompbox Circuits|
|Circuit||Input Cap||Output Cap|
|Ibanez Tube Screamer||.027uf film||10uf electrolytic|
|ProCo Rat||22nf film||1uf electrolytic|
|Boss DS-1||.047 film||1uf electrolytic|
|Dallas Rangemaster||.005uf||.01 uf film|
|Dallas Fuzz Face||2.2uf electrolytic||.01 uf film|
Let’s say you are building a treble-booster–you would want to attenuate any low frequency content before it hit the amplifier circuit. So you would put in a lower value input cap to accomplish this. The Dallas Rangemaster, perhaps the most famous of all treble boosters, has an incredibly small .005 uf cap.
Another great example of the effect of cap values on frequency response isa href=”http://folkurban.com/Site/LofoMofo-724.html”>Tim Escobedo’s LoFoMoFo. Look at the very small values for the input, output and shunting caps (R1, R3 and R2, respectively). These parts conspire to remove pretty much all the bass content of the input signal:
Alternatively, let’s say you want the majority of the useful frequency content to be passed through–in this case you would use a larger value cap, say 100nf-1uf. A rule of thumb is that a 1uf capacitor, input or output, will allow all guitar frequencies to pass through.
Variable Low-Pass Filter
Here we use a small value cap (500pf up to 50nf is a good range for experimentation) wired in the signal path of a circuit. If the pot’s wiper is at the full open position (no resistance) the signal will bypass the cap and go straight through. But as the resistance is increased, more signal will pass through the cap which will attenuate higher frequencies.
Another way to implement a low pass filter is to used a potentiometer in series with a capacitor to ground. This type of configuration can be spliced into the signal path of a circuit, but it should be noted that there is some signal loss. This is the case with all such passive circuits. Usually, there is a gain stage after a passive tone control to boost the signal lost in the passive section. For example, look at the last transistor stage in the Big Muff Pi circuit: it’s function is to make up for the signal loss in the preceding tone control.
Smoothing Diode Clipping
You can add a small-value capacitor in parallel with a diode clipping arrangement to smooth out the high-end of the clipping. This is a somewhat interesting area for experimentation.
Capacitors for Timing
Another common use for capacitors is to control the time interval of a circuit. For example, in a low-frequency oscillator, a capacitor is used in conjunction with a potentiometer to set the frequency. Our first example is a simple LFO based on the 40106 Hex inverting Schmitt trigger. The combination of C1 and VR1 set the frequency:
Next, we have a classic 555 basic monostable oscillator. In this configuration, the frequency is set by a combination of R1 and C1.
- KIERON WALKER
- SEP 17, 2022
What to Do When Alone on New Year’s Eve
The end of the year is here, and you want to do something fun to celebrate, but none of your friends is available. What are you going to do?
Don’t start stressing just yet. Bringing in the new year on your own doesn’t have to be a depressing alternative. There are tons of things that you can do solo that will still leave a smile on your face.
The list below highlights just some of the options available to you if your friends can’t make it out with you. Figure out which one matches your personality and give it a try. You can even roll a few of the suggestions together to bring some variety to your night. Before you know it, the clock will be hitting midnight, and you won’t want to stop what you’re doing.
11 Ideas for Celebrating New Year’s Eve on Your Own
- Go Out on the Town Anyway
- Have a Movie/Television Series Marathon
- Redecorate Your Living Space
- Write Letters to Your Friends and Family
- Set Goals for the Upcoming Year
- Travel to a Special Destination
- Play Your Favorite Video Games
- Start Reading a Good Book
- Work on an Arts and Crafts Project
- Host a Hangout With Other Friends
- Give Thanks and Go to Bed Early
1. Go Out on the Town Anyway
So you’re home alone on New Year’s Eve. Who says you can’t get dressed up and go out anyway? Bars, clubs, and other venues will still be packed with people ready to party the night away.
Sure, it’s always fun to have your closest friends around for nights like these, but the likelihood of running into someone you know is still pretty high. Even if you don’t, you may just start off the new year by meeting a new group of friends.
Here are a few things to keep in mind before you head out:
- Make sure you’ve arranged for a safe trip to and from the party. Free cabs and shuttle buses are usually readily available.
- Have fun, but be cautious. Your friends are usually the people who watch out for you on nights like these. Make sure you are extra careful with strangers if you don’t have someone to watch your back.
- Try sticking with familiar venues. This may increase the chance that you run into someone that you know during the night.
2. Have a Movie/Television Series Marathon
If you do decide to stay home, not much beats relaxing on the couch and watching television. New Year’s Eve can be the perfect time to catch up on television episodes you missed during the year or movies that you don’t mind watching over and over again.
As a matter of fact, between your personal DVD collection, Netflix, and Amazon Prime, it shouldn’t be difficult to create your own television marathon. You may get so involved watching a movie that you completely forget the ball dropped at midnight!
Before creating your own movie marathon, consider the following tips:
- Come up with an entertaining theme.This can range from Star Wars night to a Lord of the Rings showcase. If you like horror movies, come up with a list of the scariest ones you haven’t seen yet. If TV shows are your thing, watch your favorite episodes from your favorite show (“The Walking Dead,” “The Wire,” etc.).
- Come up with creative snack foods to eat during the marathon and in between shows. If you don’t feel like cooking, call ahead to your favorite restaurant and see if they offer any sort of party platter.
3. Redecorate Your Living Space
Have you been meaning to reorganize your house for the whole year? Maybe it just looks like a war zone inside. No matter the reason, New Year’s Eve presents the perfect time to get your home looking beautiful again.
Your renovation project can be as large or small as you want it to be. It can be as simple as sorting/recycling a stash of old magazines or hanging new photos throughout the house. You can even use the time to trim down on some of the old clothes hanging inside your closet. The list of DIY activities available to you is endless!
Should you choose to put your home first, here are a few ideas that may help you:
- Focus on a specific room or area within your house. Trying to take on your whole living area at one time can be intimidating, and it may end up leaving you feeling defeated at the end of the night.
- If your projects involve moving furniture, make sure you use furniture sliders. You can even make your own by cutting small squares made out of cardboard. Just slide them under the corners of your furniture, and you can move them around without needing another person’s help.
4. Write Letters to Your Friends and Family
The end of the year is the perfect time to reflect on what you have done and share your accomplishments with your friends. Rather than meeting up with them for drinks or sitting in front of Facebook all night, try breaking out a pen and paper and writing them an actual letter.
If you’re not sure where to start, here are some ideas:
- Use the time to come up with an annual update. Let your friends know about everything that happened every month throughout the year and what you plan to do in the upcoming year as well. If you have a chance, include some photos of yourself that your friends can put up in their homes.
- If a handwritten update seems daunting, send a short email instead.Everyone loves getting real snail mail that isn’t related to bills, but if you can’t handle writing your update, then at least take a few moments to email your closest friends and family. It can keep open the lines of communication and possibly help you start planning for next year’s New Year’s Eve activities!
5. Set Goals for the Upcoming Year
New Year’s is the time of making resolutions. While some people hate the thought of making them, others see the beginning of the year as the perfect time to start working on a new goal.
One of the things that people remember the most about resolutions is how often they fail. Many times, this is due to a lack of good planning. Why not use New Year’s Eve as a time to set up your goals and make plans to accomplish them?
A few things to remember about making goals for the new year:
- Be realistic. It’s OK to think big, but think of all the little goals that lead up to the big one. Not only will you be more likely to accomplish the small goals, but you’ll also be motivated by your success.
- Consider your support system. Don’t just focus on your goals. Think about the people that are going to help you get there. Everyone has days that they don’t feel motivated. Often, these lead to people giving up on their resolutions completely. Figure out who your personal cheerleaders are so they can give you that extra boost of energy on those days.
6. Travel to a Special Destination
Have you been waiting all year to take a vacation? Has Vegas been on your mind for a while? Disney World, maybe? Possibly even the Caribbean? Instead of waiting for friends or family, just go for it!
- Pros: It may actually be easier on you financially to just pack up and go by yourself. Rather than having to book multiple airline tickets and larger hotel rooms, you can just set out on your own personal adventure.
- Cons: The most difficult part about this option is waiting too late to schedule your trip. Most people don’t plan on being alone in advance. Luckily, there are a ton of travel sites out there, and even the major airlines offer package deals that may still be available at the last minute.
7. Play Your Favorite Video Games
Let’s face it: Playing video games is an acceptable way of life. Kids play them. Adults play them. Even some grandparents are out there playing them. Whether it’s on the Xbox, PlayStation, personal computer, or even the smartphone, people are out playing games somewhere.
- At first glance, it may seem antisocial to stay in and play video games, but it doesn’t have to be. Many games offer multiplayer options in which you can connect with other players from around the world. Just be sure to take frequent game breaks, especially at midnight.
- Even if you decide not to play with/against other players, there are quite a few games on the market that offer single-player campaigns that can keep you busy for the whole night.
8. Start Reading a Good Book
Not long ago, there was a statistic circulating that the percentage of college students that never read another book after graduating was 42%. While the number seems high, it isn’t totally shocking. It seems that lack of free time and the availability of information over the Internet have finally caused people to put down their books and forget to pick them up again.
With that being said, a quiet New Year’s Eve at home is the perfect time to dive into that book you’ve been meaning to read all year:
- Get comfortable. Find yourself a cozy corner of the house, break out a warm blanket, and maybe even throw on some subtle background music.
- Try out a recommended book. If you’re not sure what to read, check out some of the latest books on the New York Times Best Sellers list or some of the great classics listed on the Greatest Books.
By the time New Year’s Day comes around, you may be ready to make reading a permanent part of your life again!
9. Work on an Arts and Crafts Project
For those people with a creative side who don’t like being idle, an arts and crafts project might be the best way to spend the evening.
Start out by looking around your home and finding a spot that could use some extra character. Then set out to find a project that will turn heads the next time you have company. It could be a new charcoal drawing, a refinished piece of old furniture, or newly painted pieces of pottery. No matter what you decide, take the time to put your own flair into it.
If you need ideas, here are a few ways to get inspired:
- Try checking out a few craft books from your local library.
- Browse through Pinterest to see what other people have made.
- Take a walk through a craft store such as Michaels or Hobby Lobby.
It won’t take long for you to find something to do, and you can show it off for years to come.
10. Host a Hangout With Other Friends
So you decided to stay in for the night, but it’s a definite possibility that some of your friends made the same choice. If so, break out your laptop, tablets, or other devices and have a New Year’s Eve Google Plus Hangout party.
Google Hangouts allows you to connect with your friends and family through video calls over the Internet (similar to Skype). You could get your whole crew together and celebrate without even being in the same house.
While it may not be the same as going out to your local bar or club, you could make it as crazy as you want it to be—the sky is the limit! Fun ideas include the following:
- Share stories about the past year.
- Play drinking games.
- Listen to music.
- Watch the same movie.
11. Give Thanks and Go to Bed Early
The easiest option on the list may actually be the most appealing one. After a year full of running around, maybe you just want to wind down and get a full night’s rest.
Make the most of your restful evening with these tips:
- Relax. Prior to calling it a night, you could enjoy a glass of wine, a nice relaxing bath, and some soothing music. Find your favorite ways to pamper yourself before climbing into bed.
- Reflect. Before you fall asleep, take a moment to reflect on the past year, and then get ready to tackle a new one the next morning.
However you choose to spend your New Year’s Eve, don’t let being alone prevent you from enjoying it.
Happy New Year!