I have been building guitar effect circuits with stripboards for some time now. All the information i needed was obtainable through searching the internet - but all i needed to know to start with was scattered around in tiny bits and pieces. That's why i thought i should write this article about basic components. I'm not going to inner details of what the components do, or electronics theory, as knowing all the physics and math is not necesserily needed to build a great pedal. This article is meant to help you to familiarise yourself with with basic components and help you decide what to source and use. There is some really special stuff available through ebay and other sources, but i'm going to touch only the basics - the components that are easily available from any store that sells electronic components.
Another anecdote to why i wanted write this document is one lenghty conversation with my sister. She started out a new hobby recently. Gardening. She searched the web for guides and tips for the beginners, but all she found was lenghty articles about soil's pH and nitrate count. Anyone wanting to grow tomatoes does not need that information for starting out. That's good to know for those who are advanced in gardening. Beginner needs a spot on practical documentation that helps him or her to get started. Same thing here. I would have saved a lot of time, energy and even money, if i didn't have to make some of the bad sourcings of my past. So this article is for past me and anyone who is building their first builds without a ready-to-solder kit and step-by-step instructions that come along with those.
If you want to know more about what these components do, just search the internet. There is amazing amount of information on electronics available. I'll get down to business and start with the resistors.
*Hint: Don't believe everything you read - you'll be better off with learning and trying out things for yourself. To find the way you see the components you use, you'll just have to play with them. Experience gained through doing is the best and the only way to really learn.
With 9V and all the way up to 18V circuits, we're going to need 1/4W resistors. Or 0,6W. These are both small and convenient resistors. Usually about the same body size. These wattages mean how much power the resistor is capable of handling. All power ratings will work - the resistors just do get bigger bodied with every step up on that wattage scale. 1W is always bigger than 0,6W. 2W is going to look really funny on a vero... Most popular are 1/4 and 0,6W. Go with those. They are cheap and good way to begin.
Next big question: 1% or 5%? That means variance within the resistors. For example, 100K resistor can be in reality anything between 95K and 105K with those light brown four striped 5% resistors. With blueish 1% resistors the real value for 100K can be anything from 99K to 101K. Which is better? Well. It's more likely a matter of opinion than anything else. 1% resistors are more accurate, and 5% are a bit cheaper. For most circuits to work right and sound the same, the 10% variance would be ok. I bet you a bottle of cheap red wine that you won't be able to hear any difference with two TS9 clones, one built with 1% resistors and another with 5%. By the way, 5% resistors are usually made with carbon composition film, while 1% ones are made with metal film.
There will always be people who say they can hear the difference. These are the people that reverse their speaker cables on their high end stereos to see if that would sound better with their 16-bit CDs...
Resistor values we use, range from 10R (that's 10 ohms) to 10M (that's 10 million ohms, or megaohms). If you don't have the exact value at hand, you can always use the closest one. Or you could get hi-fi and set the resistors in parallel or in series to get exactly the value you want, but that's a issue for another time and document.
When i started out, i bought a starter's kit of of 5% E12. Bad thing is that when i decided to switch over to 1% resistors, i had, and still have, a fair amount of nonpopular 5% values left. I suggest that you choose your favourite and stick with it. That way your stash stays consistant. Or... You could always stock up on both.
*Hint: If you're charged more than 10 US cents per 1% 1/4W resistor, check out some other store.
Variable resistors (a.k.a. potentiometers)
Ok. Figure this: there's an open resistor inside every pot. And also, there is a conductor that touches that resistor. Let's say that it is 100K pot. Conductor, or the middle lug, touches the left lug in CCW position. Thus there's no resistance between the left lug and middle lug. But. In CW position the middle lug is connected straight away to the right lug - leaving 100K resistance between left and the middle lug. In the middle position, there is 50K resistance to both outer lugs. All this in a package that you can turn. Ingenious!
The most basic pots are the Alpha 16mm pots. Shafts are usually 6,35mm in diameter, which is the standard. You'll fit almost any knob to those shafts. Shafts have different types, like solid, D, knurled, split and so on. What does that 16mm mean? That's the width of the pot's base. 9mm pots are much smaller, and you could fit more of those in much smaller space. 24mm is another pretty popular size. You can find other brands (Bourns, Alps..) and other base sizes. There are some super high end pots available too, with price climbing exponentially. Check out the shaft lenght while you're at it.
Potentiometer tapers and values
Normal pot tapers are B, A and C. B is for linear taper. Which means that the resistance throughout the sweep grows linearly - The CCW postition with 100K pot is 0K, middle position 50K and CW position 100K. A is for logarithmic taper (sometimes referred to as "Audio taper"). Which means that the resistance throughout the sweep grows logarithmically - The CCW postition with 100K pot is 0K, middle position is onlly 10K but CW position is still 100K. C is for "Reverse Log", so it's the opposite of logarithmic with 0K at CCW, 90K at the middle and 100K at the CW position. Some designs ask for W taper, which is log-antilog taper. Starting like logarithmic from zero, middle position is 50K like in linear and last 50% acts like reverse log. These are rarely used, but i though you should still know that.
Some documentation states that european way of indicating pots is A and B swapped, but i've never come across linear pot marked as A taper. Other documentation found on the internet says that those are thee olde way of marking the tapers. I think it's best to buy pots as linear or logarithmic instead of A or B.
Pots come in various values. From 100 ohm to 5 megaohm. Thankfully these don't come in as many values as normal resistors. Normally in our builds we would be using values like 1K, 2K, 5K, 10K, 20K, 25K, 50K, 100K, 200K, 250K, 500K and 1M. Yup. It's going to take a lot of money and time to have a stash with all three basic tapers and number of all basic values. For starters, i'd suggest to grab 1K, 10K, 100K and 500K pots. Those are probably the most used values.
*Hint: Print yourself a pot lug numbering guide like this: http://mirosol.kapsi.fi/varasto/boxes_other/pots_switches.png
Trimmers, or trimpots, work exactly the same way. But these are meant to be mounted on the circuit boards and set once for their purpose. Normally with 6mm width, you can find these little things for less than 10 cents a pop. And it's good to stock these up. Even if you don't think so right now, you'll be needing them eventually. Trimmers are usually used to bias transistors, so you're really going to need them. Sooner or later. More than one of each value.
Now. Here we do have a lot more to choose from. And we'll have to make some painstakingly hard decisions. There are two basic types - capacitors without polarity and ones with polarity. Normally most of the capacitors with values from 1pF to 820nF are non-polar and most of 1µF to 1000µF are polarized. Both do have exceptions. Capacitors are usually rated to have 5-10% varience within their values. Some electrolytics have even higher variances, like 20%. But we don't mind. From a first time builder to professional boutiquer, we're all using the same components from the same factories with the same variances, so even 10% variance can't be a problem in a real world. In electronics theory it might be..
*Hint: Print yourself a capacitor value conversion chart (something like this: http://www.justradios.com/uFnFpF.html) and pin it to the wall at your desk.
Ok, let's start with listing some of the basic types of non-polar capacitors and dissect the list after that:
-Polyester Plastic (box or tubular)
-Metallized polyester (panasonic style)
-Other, like Silver Mica, PIO, Polyester in some exotic plastic like PETP, Polystyrene, and so on (there's just too many to list every type ever used).
Pros, cons and my personal biased opinions of each type listed:
-Ceramic discs: +Super cheap, cheaper than resistors. -Produce unwanted noise. -Unnatural sound
I'd use these for some non-critical purposes with values below 500pF. But nowhere else. 470pF ceramic disc is pretty cool to try for BMP to get some 60's-70's warm, noisy feeling to it. These come in values from 1pF to 470nF.
-Polyester Mylar, a.k.a. Greenies: +Cheap. -Huge bodies in bigger values. -Cheap?
I can't find that much negative sides to these. Underrated caps, that you can find in very cheap assortments to get you started. Usable sized values vary from 1nF to ~220nF, while even 100nF is noticeably bigger than 47nF cap.
-Multilayer/Monolithic ceramic: +Small. +Relatively Cheap (100 for $3 is very decent deal). -None that i can think of.
These come in values from 1pF to 1µF and they are all pretty much the same size. Pretty sick, but these are cheap to stock on and you're not going to have a bad time with them.
-Polyester plastic boxes (or axial tubes): +Industry standard for audio. -Relatively expensive.
In my opinion, a bit overrated caps with prices around 10 to 50 cents a piece. Good to have and use anywhere. Body sizes stay reasonable even with values like 1µF and 2,2µF. values are usually from 1nF to 1µF. Bigger ones exist, but these are not used so often. At least, that's how it seems.
-Metallized polester caps (a.k.a. panasonics): +Sizes are sane. -Quite expensive.
Really good basic caps, that you can score 50 pieces for 10 bucks. Usual values from 1nF to 1µF. I'm using more and more of these all the time.
All of the above are normally rated to handle voltages like 50V, 100V or 200V, so they are just perfect for our purposes. I personally feel that caps rated over 300V are too much for these circuits. And again, higher tolerance for voltages makes the bodies bigger and bigger.
Then the values over 1µF. These are usually aluminum electrolytic or tantalums. Basic electrolytics are cheap, but they are known to just die by time. Tantalums easily cost 10 times more, but they are small and last at least as long as cockroaches after the next world war. Electrolytics are rated all over the map for the maximum voltages. For our purposes, it's 16V and up. These come in all the way up to few KVs and higher. I'd use anything rated from 25V to 250V. Bigger tolerance means bigger component body. Do not use caps rated 10V or lower in these 9V circuits. Running the cap near its voltage tolerance will reduce its life expectancy even more. Some documentation on the internet says that you should always use twice the tolerance - meaning that for 9V ciircuits the caps should be rated at 18V at least.
Let's do the same dissection with these two types:
-Aluminum Electrolytic: +Cheap. -Relatively short life span
Good for power filters. Values range from 100nF to 1F.
-Tantalum: +Long life. -Relatively expensive.
I love these things. You can use four of these before you occupy the same space that 100V 10µF takes.Come in lower values topping at 33µF-47µF.
*Hint: You'll need to do this only once, but wire a 9V battery's plus terminal to the minus side of the 10µF aluminum electrolytic cap. Then battery's minus terminal to the plus side ot that cap. Now hands off and wait. You'll never be careless about electrolytics again.
Then we have non-polar electrolytics. These are not too popular, but they offer higher cap values without the polarity. These are more expensive than the usual parts.
Almost all capacitors come in various kinds of packages, like radial and axial. If the value, variance and tolerance for voltage is the same, then it's the same cap - regardless of it being new-old-stock-american-paper-in-oil-super-mojo axial or humble two cent radial electrolytic from tayda. It does exactly the same thing in both cases. Other costs you that two cents and the other, well, up to $8. But the latter will look much sicker on the board. And no. It doesn't sound better. It's exactly like comparing 180 horsepower Kia and 180 horsepower Mercedes. Both will take you to your family's summerhouse in the same amount of time. Latter will just look sicker on the lawn when you get there.
Once again. You'll have to make your own choices based on your own preferences and experiences. Or... You could always stock up on all of them.
*Hint: Nothing you can do with a working build is never wrong. Finding a default fault in a component type and taking advantage of it = profit.
That was my brief introduction to passive components. In the near future, i'm planning on writing a similar introduction to other components, like diodes, transistors and ICs.