Resistor Color Code Training

[PICMICRO]

The traditional "bla bla bla very good wife bla bla bla" method is inherently slow.
To be quick you need to directly associate colors with numbers.
I would like to share a little training software I made to aid this.
The app
While using that kit, It is helpful to follow this
First look at the third color.
If its black, its xx ohms. Like 47 ohms, 56 ohms etc
If its brown, its xx0 ohms. Like 100 ohms, 330 ohms etc
If its red, its x.x Kohms. Like 2.2 kohm, 3.2 Kohm etc
If its orange, its xx Kohms. Like 33 Kohm
If its yellow, its xx0 Kohms.
If its green, its x.x Mohms.
Now, look at the first two colors.

I hope this will be useful for beginners or professionals as well.

 

[WTP Pepper]

A few points...
1. How does that help with 4 & 5 coloured resistors. Also the tolerance used to be shown as a 4th colour.
2. Wired resistors are a thing of the past. SMT is the way to go.
3. I would hope most professionals would know this backwards.
Otherwise well done. I'm sure most beginners will find it useful.

 

[unclejed613]

for teaching the digits, i always found it useful to hand somebody a hunk of color coded ribbon cable that i have a huge roll of. 10 wires, color coded with the same colors as the resistor color code, i think it was called "rainbow cable". also, the color of the multiplier says "add this many zeroes" to the two (or three with 1% resistors) digits. with gold and silver multipliers, i used to remember it as "gold is a low resistance, but silver is lowest"

 

[colin55]

Some of the color-combinations do not exist on real resistors.

The number 10 is misleading and the English wording on the application is poor.

 

[JimB]

Resistor colour code is just like another foreign language.

All the learning aids in the world will only take you so far, in the end you just have to get in about it with the natives!

Just get a box of assorted resistors and work out what they all are!

JimB

 

[Dean Huster]

2. Wired resistors are a thing of the past. SMT is the way to go.

1. When you have thousands, maybe tens of thousands of components available in your home hobby, you use them rather than going out and wasting a bunch of money on SMT parts. That's like starting over in your hobby.

2. Last time I checked, there's not a single item of my test and measurement equipment, short wave receivers or antique radios that use SMT. If they need repair, I need to know the color code.

3. Color codes sometimes cross component barriers. Older wiring harnessessessesses often had base colors and one or more stripes, coded on the schematics something like "2-5-3".

4. Just because most cars are now fuel-injected doesn't mean that an auto mechanic doesn't have to know anything about carburetors.

 

[unclejed613]

it's also helpful to know (or at least be familiar with) the standard decade values for 5% resistors. 5% tolerance resistor values will always be a multiple of one of the following:
1.0 1.1 1.2 1.3 1.5 1.6 1.8
2.0 2.2 2.4 2.7
3.0 3.3 3.6 3.9
4.3 4.7
5.1 5.6
6.2 6.8
7.5
8.2
9.1
this chart is somewhat easy to memorize since it only has 24 digit pairs.
so the value is 2 digits for the number, one digit for the multiplier, and a 4th band for the tolerance (gold for 5%, silver for 10%, and occasionally a red band for 2%). so a red-yel-brn-gold would equate to a numeric coded resistor of 241-5% and a value of 240 ohms.
this is true whether it's color coded or numeric coded. the 1 percent tolerance resistor color code uses 4 colors for the value. 3 digits for the number, 1 digit for the multiplier, and a fifth brown band for the tolerance (a 1 for 1%). since the 1% chart has 96 triplets of digits, it's not easy to memorize, and it's best to keep a chart.
1.00 1.02 1.05 1.07 1.10 1.13 1.15 1.18 1.21 1.24 1.27

1.30 1.33 1.37 1.40 1.43 1.47 1.50 1.54 1.58

1.62 1.65 1.69 1.74 1.78 1.82 1.87 1.91 1.96

2.00 2.05 2.10 2.15 2.21 2.26 2.32 2.37 2.43

2.49 2.55 2.61 2.67 2.74 2.80 2.87 2.94

3.01 3.09 3.16 3.24 3.32 3.40 3.48 3.57 3.65 3.74 3.83 3.92

4.02 4.12 4.22 4.32 4.42 4.53 4.64 4.75 4.87 4.99

5.11 5.23 5.36 5.49 5.62 5.76 5.90

6.04 6.19 6.34 6.49 6.65 6.81 6.98

7.15 7.32 7.50 7.68 7.87

8.06 8.25 8.45 8.66 8.87

9.09 9.31 9.53 9.76

also keep in mind the multiplier gets pushed over a decimal place, so the multiplier for a particular decade will be one less than on a 5% resistor. for instance a 5% resistor of 75k, would have a color code of vio-grn-orn, for a numeric code of 753 (75 with three zeroes). a 1% resistor of the same value would have a color code of vio-grn-blk-red for a numeric code of 7502 (750 with two zeroes).

the numeric codes have become more popular with many manufacturers since laser etching processes make it easier to mark components, but many manufacturers still use color coding. i once built a prototype for an engineer, and after researching his parts, actually saved his company lots of money in building the prototype, because he had specified 1% resistors for such mundane things as 5V logic pullups, so he had 475 ohm resistors where a 470 ohm 5% would suffice. so we built the prototype and tested it, and it worked properly. a week later, the engineer brought it back. he was making some circuit changes, and asked why we replaced the 1% resistors with 5% resistors, and i explained the 5% resistors worked properly. he said that's great, but he couldn't read the color coded resistors.... he was color blind, and the 1% resistors were numeric coded. once the unit became a production model the 5% parts were fine, but he needed the prototype with the 1% numeric coded resistors....

 

[WTP Pepper]

4. Just because most cars are now fuel-injected doesn't mean that an auto mechanic doesn't have to know anything about carburetors.

Not the case if you visit my local Ford dealer

 

[IntelGent]

A question for the moderator responsible for approving 1st postings.
Yesterday I created an account under user name Zzaapp and posted on this thread a link to an available for free project to make a resistor color code wheel. My question is, why, after it was apparently approved by a moderator due to it being a first time posting, was my account banned....without any reason given? Does this forum not want people posting anything helpful? I could see it if it was something illegal or profane, but since neither was the case, I do not see the logic in the ban.

The problem with linking to things is that they go away. Please upload the instructions and pdf to ETO.

 

[MrAl]

Hi,

I think you should take that to the other place on this forum, Site Issues and Feedback.

Anyway, i agree that color code is still a necessary thing. It may be on it's way out, but it's not quite out yet.

As to reading the colors, long time ago back when i worked mostly with 5 percent resistors, i used them so much that i learned their color bar patterns rather than to bother with the breakdown of the individual colors. It was not a matter of seeing yellow and thinking "4", and seeing violet and thinking "7", then seeing orange and thinking "multiply by 1000", it was just a matter of seeing all three at once and knowing right away what resistor it was. This is analogous to a word (such as in English) rather than the individual letters themselves. We only see 'w' -- 'o' -- 'r' -- 'd' one letter at a time when we are first learning to read, but after a while we see it as one single object 'word' and we know what it is right away. On a resistor the colors form a word made up of colors rather than letters of the alphabet, and because there are only 10 colors and as Collin pointed out not all color combinations are needed it's much faster to learn. I see 'yellow' 'violet' 'orange' as '47k'.
Another way to look at this is to use the first letters of the colors (we can only do this for some colors but this is just an example). For the 47k resistor it would be 'yvo' which is a word like construct, but it's even simpler than that once you see all the resistors day after day for years. It becomes automatic like reading a sentence. In fact, for many resistors mounted across a PC board they read just like a sentence. If one of the 'words' is not right you know the assembly dept made a mistake

 

[3v0]

Not every question has a binary answer and this is one of them. If you are going to use banded resistors frequently then by all means go ahead and memorize the color codes. In time you will as MrAl said learn to recognize the patterns. But if you only use them now and then you will soon forget them so why bother.

 

[Paul_L]

It's only good if you can tell what color is what. There was a time when they were easy to read; now browns, reds, blues… look too similar. SMT resistors are worse some are too small to see. Perhaps it's just bad vision.

 

[MrAl]

Hi Paul,


I know *exactly* what you mean. For a while (quite a while back now) i had trouble telling the difference between some of the reds and oranges. They looked very much the same. But then i realized the main problem was the lighting used to view the resistors. Lighting comes in a wide range of color tints that are very subtle. Most indoor incandescent bulbs put out a nastly yellow orange sort of glow, which really causes a big problem when you're trying to distinguish one color from another. LED lights can be deceiving too, because they are available in many subtle tints too including 'warm white' which also causes a problem with color differentiation.

The solution was to get an LED light that puts out light rated at 6500K, which is just about daylight. Using this color LED works great and those red/orange stripes are much easier to tell apart. That's all i use now.

Keep in mind again that white LEDs put out a spectrum of colors and some of them have various tints, from yellowish to greenish to blueish to pinkish, so it may take a couple of tries to get the near perfect 6500K color LED. Some of the manufacturers bin their LEDs as to color spectrum, and sometimes you can order based on what you want that way, usually for the higher power LEDs like the 1 watters and above.

If you get a chance try that and see how much difference it makes. It really changes the readability of the color bands.

I do feel sorry for the color blind persons though, their only resort might be to use an ohm meter for every resistor.

 

[3v0]

IntelGent

The problem with linking to things is that they go away. Please upload the instructions and pdf to ETO.

Thanks

 

[ghostman11]

Not every question has a binary answer and this is one of them. If you are going to use banded resistors frequently then by all means go ahead and memorize the color codes. In time you will as MrAl said learn to recognize the patterns. But if you only use them now and then you will soon forget them so why bother.

please dont tell LG this as he speant many weeks learning them inside out and backwards lol

 

[3v0]

At his age any learning is good regardless of the subject. Did I say that....

 

[Mr RB]

These days I've been reaching for the ohmeter a lot more than usual, no problem seeing the colours but some brands of 5 band 1% resistors are a real pain, especially when they start with a brown band at each end and the bands are equally spaced so there is no way to tell which end is which... Bah.

 

[Dean Huster]

And decent PCB manufacturers (e.g., Tektronix) made sure that all parts were layed out on the board such that they were readable in the same direction if possible. For instance, all resistors were installed such that the horizontal one's bands read left to right and the verticel one's bands read top to bottom. Caps were similar so that the markings were always readable and not flipped over to the opposite side. A lot of that is thanks to automated component inertion equipment, but Tek was doing this long before automation. Like Mr. Al, most of us "old timers" read the color code more like words rather than individual letters. We don't see that third band as a multiplier or number of zeros to add .... it tells us that the part will lie in the hundreds of K or tens of ohms and the first two digits just pop into our heads. As also mentioned, knowing the 24 standard values per decade is a great help, especially on older equipment where the colors have shifted a bit or the parts have heated up to the point that whether originally orange, red or brown, it looks brown now and you know that it can't be 41K, so must really be 43K.

 

[Mr RB]

...
... it looks brown now and you know that it can't be 41K, so must really be 43K.

For sure it used to be like that. But with metalfilm 1% resistors they come in all the fractional sizes between all the old common sizes so you can no longer rely on sensible values, and like I said with 5 bands total and a brown paint band at each end they can get real confusing!

Even in parts storage it's a pain, as most people sort them into the multiplier band (ie 10's of k, 100's of k etc) but now with some being 5 band...

 

[trash]

As mentioned above, resistor colour codes are just another language and not a particularly difficult one to learn.
But as 3v0 pointed out, if you don't use them a lot you will forget them and it's easy enough just to use a chart or app which you can look up any time.

I was been doing electronics from a very young age and I cannot remember not being able to read resistor colour codes. It sounds strange, but it's like reading. If you can remember back to a time when you knew you couldn't read, and try to remember being illiterate, you can't remember.

I have always been able to read resistor values subconsciously. I look at the resistor and I do not see colours or numbers, I just see the value of the resistor. Like reading this sentence, you do not consciously 'see' letters or words, you see meaning of each word as you read it.

A job interview I did many years ago I was given a list of resistors by the interviewers. It had about 20 resistors drawn on it.
"Can you tell us what the values of these resistors are ?"
I read 19 of them of in about 20 seconds. The last one was three violet bands with a gold band.

Right now everybody is doing the exact same thing I did. I stopped, saw 777 in my head. 10^7 is 10,000,000 so I said 770Mega ohm.
It took an extra 2 seconds to actually have to think about it.

The boss turned and asked his offsider if I was correct. They had never seen anybody answer them that quick.
The other guy had to get his sheet out and ask me to repeat my answers slowly.

The last one he looked at the question sheet and said, "Oh sorry, I ran out of red ink, those purple bands are supposed to be red."
Oh, ok, so you want 2.2k as an answer !
The boss asked, "So is three violet bands 770M ?"
"Yep, he's the first person we've had get 21 out of 20."

I still think about this test because it reveals how I read resistor colour codes even though I'm not consciously aware of how I do it.
The first thing is to work out which band is the tolerance band.
Usually there is a slightly bigger gap between it and the next band. On the older carbon film 5% tolerance resistors, the gold band is obvious.
On the 1% metal film resistors, it can be a bit a bit hard on the eyes.

So once you know where the tolerance is and which way to read the resistor, the multiplier band is the first value to read (3rd or 4th band), and then the 2 or 3 value bands.

Remembering the colours, it's just 12 colours to remember. Simple repetition helps most people remember them.