Why is it so hard to accurately read resistor values on resistors.

 

It's not hard if you know the colour code and which end to start at, easiest way is use an ohm meter or Dvm.

 

I have a bit of difficulty reading color codes too, but mostly because of my true color perception issues.

1 Black; 2 Brown; 3 Red; 4 Orange; 5 Yellow; 6 Green; 7 Blue; 8 Violet; 9 Grey; 0 White.

Red and Green tend to run together on me, and blue and violet are difficult for me to discern. If I think I see red in the blue then it's purple. But distinguishing red from green has been typically difficult. If I have enough of the color and enough light I can usually tell. But sometimes Green and Brown run together as well. That's why I like resistors with numbers on them instead.

Do you know how to determine the value of a resistor if you can determine the numbers?

 

It would be a lot easier if the body of the resistor was white. Whoever thought that green/red/brown was a good colour for a resistor body?

 

Why is it so hard to accurately read resistor values on resistors.

You ask a question that is essentially impossible to answer since you give no clue as to what you mean by it being so had to accurately read resistor values.

 

1. Are you read the values from the color code, 4 or 5 colors?
2. Did you measured it on PCB or indepently?
3. What kind of meter did you used to measure the resistor? (Analog needle meter or digital multimeter)
4. Which brand of multimeter did you used?
5. What you saying that the accurately of measured was unstable or measured many times but they were all different.
All we need to know more detail?

 

I have a bit of difficulty reading color codes too, but mostly because of my true color perception issues.

1 Black; 2 Brown; 3 Red; 4 Orange; 5 Yellow; 6 Green; 7 Blue; 8 Violet; 9 Grey; 0 White.
(some text removed for clarity)

The numbers are off by one -it starts with black being zero.

0 Black; 1 Brown; 2 Red; 3 Orange; 4 Yellow; 5 Green; 6 Blue; 7 Violet; 8 Grey; 9 White.

On my first attempt to to correct the table above I started with black being one and didn't catch the error until I got to six. Seems like an easy mistake to make.

I find that the color bands on the carbon film resistors I use are difficult to read because I use florescent lighting that seems to have a poor color rendering index -the spectrum is not smooth, so sometimes the colors are hard to distinguish -for example, is that a red stripe or a brown stripe? The small metal film resistors are even worse.

My solution to this problem is to keep an LED flashlight handy and when in doubt check under the flashlight. The LED in the flashlight happens to be pretty good at making the colors readable.

 

Hello,

There are several color codes for the number of bands on the resistor:



Bertus

 

This posted chart says it better than I could. As far as reading the values, there is also the fact that there are two sets of values, the 10% tolerance list and the 5% tolerance list, and so if you read a value that is not on the list then you need to look at it again because it is probably wrong. To see those lists of values you can look at the resistor section of most electronics suppliers catalogs. Of course, there are also 2% and 1% resistors but most consumer electronics uses 10% tolerance because it is cheaper.

 

The numbers are off by one -it starts with black being zero.

OOPS! WOW! Really messed that one up. Good catch. Yes, and thank you for the clarification. I knew black was zero. Don't know how I missed that so easily. Gotta start reading my own posts a little more closely.

Thanks again.

 

Hello,

There is even an other color coding for resistors according the EIA:



As you can see, there are 3 bands for the value, one for the tollerance and one for the temperature coefficent.

Bertus

 

From my high school days:

Bob...............0
Brown.......... 1
Raped...........2
Our................3
Young...........4
Girls.............5
But...............6
Violet...........7
Goes...........8
Willingly.......9

 

Hello,

@gramps , there are many of those lists:
https://en.wikipedia.org/wiki/List_of_electronic_color_code_mnemonics

Yours is a bit offensive.

Bertus

 

The best one I ever learned and one that we teach is:

Black Brown Red Orange Yellow Green Blue Violet Grey White.

 

In high school one summer session the technician in our TV studio made color code flash cards for me and it worked beautifully. Still, more than 50 years later when I see a color coded resistor I see the value, not the colors. Not only was he a good teacher, but also a really good technician.

 

In high school one summer session the technician in our TV studio made color code flash cards for me and it worked beautifully. Still, more than 50 years later when I see a color coded resistor I see the value, not the colors. Not only was he a good teacher, but also a really good technician.

Same here.
It is like morse code. You don't decipher dots and dashes. You hear the entire letter and word.

 

Yes, in this day and age it is quite offensive. In those day (55+ years ago) things were different. I'm not saying it was right; good or bad, society had a different attitude then.

 

Hello,

@gramps , there are many of those lists:
https://en.wikipedia.org/wiki/List_of_electronic_color_code_mnemonics

Yours is a bit offensive.

Bertus

It always amazes me how few references on the resistor color code ever mention the fact that the order of the central part of it was chosen to be the same as the rainbow. That gives you the central six. The other four, two at each end, are simply the extreme of the neutral colors -- black and brown at one end and gray and white at the other. I can't count the number of students that couldn't remember what color came after orange or after green but had no problem telling you instantly the order of the colors in the rainbow.

 

The American or European resistors I buy have proper painted color rings. These are high quality resistors that are used in high quality electronic products.
But cheap Chinese resistors have very poor color rings where red, orange and brown are the same and green and blue are the same. The color rings are painted by a shaky hand??

 

I personally really dislike the color coding, but apparently some people can understand it and like it. Anyways, I just use a multimeter. If it's in a circuit, if possible, I remove it, measure it, and place it back in. But honestly they should just put values on it. Just my opinion.