# Organizing resistors [closed]

I have recently started playing with Arduino, as well as electronics in general. This means I am a complete noob. I needed some resistors for a project, so I ordered a variety pack. I emptied the packs into a parts organizer. I put the pack I ordered into separate drawers in order. Once I did that, I started putting other resistors I had into the drawers. This is where my question is. I have a bunch of 220 ohm resistors. Some came from the Arduino pack, and some from the pack I ordered. I have a number of 200 ohm resistors, from somewhere I dont remember.

Is there a big enough difference to separate the 200 ohm from the 220? Or are they "close enough" that it doesnt matter? Does this apply to every resistor that is "close"? Another example is I have 2k and 2.2k resitors.

• sometimes it will matter, sometimes it won't. some people might be more disciplined than me, but as cheap as they are it isn't worth worrying about for the most part. I rarely put resistors back :( – jbord39 May 8 '17 at 2:43
• It will matter in some projects (and it wont in most projects). I have the mindset that if I need a very specific value then I'll likely have to order some other specific components too, so I don't bother making my personal stock excessively detailed/divided. – Wesley Lee May 8 '17 at 3:16
• p.s.: IMO it also makes a difference where you live. If you have easy access to decent parts suppliers, then you really shouldn't worry too much. – Wesley Lee May 8 '17 at 3:17
• Duplicate of Organizing electronic parts? – Olin Lathrop May 8 '17 at 12:00

It matters when it matters, and doesn't when it doesn't. That's not much of an answer, but that's the simple truth. It depends, and sometimes, it does in fact matter, and other times, it doesn't.

However, the resistors ARE different. Let's go on a small aside and discuss why resistors have the values they do. 220...680... 470... it all seems a little arbitrary, doesn't it?

They're actually determined by approximate geometric sequences called the E-series of preferred numbers.

They're a slight variation on the Renard series of preferred numbers. Basically, it's a series that subdivides a power of 10 into a certain number of steps, and any two adjacent steps have a roughly constant ratio.

Let's take 100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 680, 820. Familiar numbers, right? Now, obviously we are rounding some digits off, but if you divide any of those numbers by the larger adjacent value, it will always be somewhere near 0.83. This sequence is specifically using a constant ratio that results in 12 numbers spanning a power of 10, or in other words, each power of 10 will be divided into 12 values.

What's the point of all this?

Error. Subdividing powers of 10 into these fixed ratio geometric sequences results in values that minimize relative error for any given value. So these values are chosen because they are always going to minimize how far off an arbitrary resistance value will be from the limited available values that are manufactured.

What does this have to do with your 200 vs 220 resistor question? Everything, actually. There are several E series, each one with different numbers of subdivisions. The roughest is E6 (with 6 divisions), then there is E12, E24, E48, E96, and even E192. These numbers of subdivisions are not chosen arbitrarily.

They match up to resistor tolerance. Adjacent E6 values require resistors of at least 20% tolerance or better for subdivisions of that granularity to matter. Above 20%, and two adjacent values will overlap due to the wide tolerance window, and then, as you say, they're "close enough" and the difference is not very meaningful anymore.

E12 corresponds to 10% resistor tolerance, and E24 to 5% resistor tolerance. 200 and 220 only appear starting at the E24 sequence. But, since virtually every resistor made is at least 5% tolerance, or often 1% (E96 correspondence), that means any two values that appear on the E24 sequence are meaningfully different and thus, the resistors are functionality different in a way that actually matters.

So, at least from the standpoint of the math, unless you have 10% tolerance resistors, 220Ω and 200Ω resistors are, in fact, not 'close enough'. The difference is real and measurable. Now, for many usage cases, you can definitely just plop in either of those resistors when a schematic calls for the other. There are also cases where you can't, or at least, doing so will result in something having 10% error (like, for example, the output of an adjustable voltage regulator. Given that most chips have a voltage range of ±5%, such a large error could be potentially destructive).

That said, I totally just have a drawer labeled '220Ω' that secretly has a bunch of different values somewhere between 200Ω and 220Ω. Then I do that thing everyone hates and actually figure out the resistor color code and pick the one I actually want.

As for SMD resistors, I never mix these in the same drawer/cubby/spot. 0402 won't even have any markings, and 0603+ often have weird markings that aren't any kind of resistance value, and include letters. Maybe it's hex? Cyrillic? I don't know. I try to avoid reading SMD part markings as much as I can.

You didn't ask, but I recommend these for through hole or larger component organization. You can use a label maker to label them, and they have 64 drawers per unit.

As for SMD components, I will put different sizes but the same value (so 0805, 0603, 0402 1K resistors would all get lumped together), and I use a couple of these 144 cubbies of organizational excellence. The multiple of 6 numbers make them perfectly suited for E Series values too!

They are seriously life changing. LIFE CHANGING. I love mine. I think there are also some clones of it that are a bit cheaper, but I've simply linked the brand I have (and thus can personally vouch for).

• Very helpful!!! Thanks so much. :) +1 But where do I get one of those in the picture? – jonk May 8 '17 at 3:54
• do you have a link to the item in the picture? – dandavis May 8 '17 at 4:13
• @dandavis I finally found it at: amazon.com/dp/B00A15YHJY – jonk May 8 '17 at 5:03
• Do you need to take the SMT parts out of their tape packaging to put them in that box? I'm not sure if that would be a good thing for me, I tend to just keep them in their tape and sort them in bags. – Joren Vaes May 8 '17 at 5:56

I stopped using the little drawers, they're just annoying.

For SMD ICs and other parts, I use 10x15cm photo albums like so:

A DigiKey/Mouser bag fits perfectly inside the plastic pockets, and the label is visible. It is perfect! I don't use any order. Instead I keep a spreadsheet along, so I can Ctrl-F a chip name, and I instantly know in which binder/page it is.

For thru-hole ICs, I cut antistatic foam in A4 paper size, slip than inside A4 transparent sleeves and put them in a binder. So, for example I have a foam sheet full of opamps, and my spreadsheet says "NE5532 is in top left corner of page 2".

For passives, the system is even simpler. I have plastic shoeboxes in which I put cardboard cards with the values printed on them, in order, just like a stack of photos. I flip through them with a finger and drop the Mouser bag in the proper spot. It is easy to insert values in the sequence, and easy to find them since they are sorted.

If you are a seasoned professional, you will have needs for power WW resistors all the way to 0.01% R networks for ratio gains that must be paired for differential amps with excellent matching to retain high balancing for common mode rejection ratio (CMRR) in high gain diff amps.

You can save on bench testing by relying on simulators then choose the values you need or rely on bench testing and have a kit of 156 values with 3120 pcs for < \$10 on ebay or amazon.

You cannot design a precision regulator where a 1% regulated voltage depends on the ratio of 0.5% parts with a precision Vref.

You needs will vary, but a kit of 1% standard parts may last you for a long time.

Package include:
3120 x 1/4W 156 Values Resistor

1.0Ω    10Ω 100Ω    1.0KΩ   10KΩ    100KΩ   1MΩ
1.2Ω    12Ω 110Ω    1.1KΩ   11KΩ    110KΩ
120Ω    1.2KΩ   12KΩ    120KΩ   1.2MΩ
1.3Ω        130Ω            13KΩ    130KΩ
1.5Ω    15Ω 150Ω    1.5KΩ   15KΩ    150KΩ   1.5MΩ
1.6Ω        160Ω    1.6KΩ   16KΩ    160KΩ
1.8Ω    18Ω 180Ω    1.8KΩ   18KΩ    180KΩ   1.8MΩ
2.0Ω    20Ω 200Ω    2.0KΩ   20KΩ    200KΩ   2.0MΩ
2.2Ω    22Ω 220Ω    2.2KΩ   22KΩ    220KΩ   2.2MΩ
2.4Ω    24Ω 240Ω    2.4KΩ   24KΩ    240KΩ
2.7Ω    27Ω 270Ω    2.7KΩ   27KΩ    270KΩ   2.4MΩ
3.0Ω    30Ω 300Ω    3.0KΩ   30KΩ    300KΩ   3.0MΩ
3.3Ω    33Ω 330Ω    3.3KΩ   33KΩ    330KΩ   3.3MΩ
3.6Ω    36Ω 360Ω    3.6KΩ   36KΩ    360KΩ
3.9Ω    39Ω 390Ω    3.9KΩ   39KΩ    390KΩ   3.9MΩ
4.3Ω    43Ω 430Ω    4.3KΩ   43KΩ    430KΩ
4.7Ω    47Ω 470Ω    4.7KΩ   47KΩ    470KΩ   4.7MΩ
5.1Ω    51Ω 510Ω    5.1KΩ   51KΩ    510KΩ   5.1MΩ
5.6Ω    56Ω 560Ω    5.6KΩ   56KΩ    560KΩ   5.6MΩ
6.2Ω    62Ω 620Ω    6.2KΩ   62KΩ    620KΩ   6.2MΩ
6.8Ω    68Ω 680Ω    6.8KΩ   68KΩ    680KΩ   6.8MΩ
7.5Ω    75Ω 750Ω    7.5KΩ   75KΩ    750KΩ
8.2Ω    82Ω 820Ω    8.2KΩ   82KΩ    820KΩ   8.2MΩ
9.1Ω    91Ω 910Ω    9.1KΩ   91KΩ    910KΩ   10MΩ


REF

For bandoliered resistors (paper strip holding them together), I write the value on the bandolier then store the resistors in component drawers like this one from RS. Each drawer is labelled to cover an order of magnitude (<10R, <100R, <1K, <10K, <100K, <1M etc, and the drawer is split into three compartments, with smallest values in the back (e.g. 10K to 20K), middle in the middle (22K-47K) and largest at the front.

It works well for me for general purpose resistors for prototyping (for larger quantities each one gets its own drawer). It doesn't take up much space and is quite fast to find a suitable resistor or quickly choose an alternative value.