Hi, I’m studying the AAC textbook and on this page:

https://www.allaboutcircuits.com/worksheets/resistors/

Question 8 has three questions which aren’t solvable with the information given in any linked resources from the site. We’re supposed to:

“Determine the nominal resistance values of these resistors, given their band colors, and also express the allowable tolerance in ohms.

For example, a 25 kΩ resistor with a 10% tolerance rating would have an allowable tolerance of /- 2.5 kΩ.”

But these three aren’t solvable with the provided info:

Grn, Brn, Yel
Org, Org, Gld
Vio, Red, Sil, Gld

I looked around elsewhere on the internet and found that three-band resistors are 20% tolerance by default. That solves the first one. The second one requires you to know that a third metallic band is a 0.1 (G) or 0.01 (S) multiplier. Finally, the third question is still mysterious to me even though I understand how the given answer was arrived at (72 x 0.01 ±20%) because I couldn’t find a resource saying how a gold fourth band ever equal a 20% tolerance.

Unless I completely missed it in the provided and linked materials, I think including this information on-site would be better than having the student, who is a noob at this point, “figure it out for themselves” because there’s no way for us to know whether the question is a mistake, what happens in this special case when the fourth band is silver (if gold here is 20% tolerance, is silver 40% tolerance or 10% tolerance?) or when we would expect to encounter such specimens in real life. Other than that, I’m enjoying the course.

Thank you.

 

I can’t edit the post but two corrections are the third question has a 5% tolerance and silver would be 10%. The calculator shows this but otherwise the info is nowhere else, including in the text on the calculator page. Thanks.

 

Wecome to AAC.

I’m sorry that you haven’t had any response to your post yet. I am trying to track someone down who can be authoritative.

I’m glad to hear you are enjoying the course and hope to see you here, on the forums, with questions and helping others. Anyone who knows more about something than a person seeking help is an “expert” right up until they exhaust what they know. Anyone who helps out before they hit that limit, and is transparent about it, is a great asset here on AAC.

Again, welcome, and thanks for joining us.

 

Wecome to AAC.

I’m sorry that you haven’t had any response to your post yet. I am trying to track someone down who can be authoritative.

I’m glad to hear you are enjoying the course and hope to see you here, on the forums, with questions and helping others. Anyone who knows more about something than a person seeking help is an “expert” right up until they exhaust what they know. Anyone who helps out before they hit that limit, and is transparent about it, is a great asset here on AAC.

Again, welcome, and thanks for joining us.

Hey, thanks for your reply! Yeah, I noticed that this site seems mirrored to similar ones like eev blog (idk about that specific one) so I wasn’t sure reporting this issue here was the best place. It just seemed better to post the issue than ask for individual help so subsequent readers can benefit from the correction.

I’ll be sure to poke in to see if I can help. As of now, I don’t know much but I guess I know more than some people on day one.

Cheers,
Michael

 

Hey, thanks for your reply! Yeah, I noticed that this site seems mirrored to similar ones like eev blog (idk about that specific one) so I wasn’t sure reporting this issue here was the best place. It just seemed better to post the issue than ask for individual help so subsequent readers can benefit from the correction.

I’ll be sure to poke in to see if I can help. As of now, I don’t know much but I guess I know more than some people on day one.

Cheers,
Michael

AAC has some sister sites, but AAC is the original and the content here is generally originating here. It’s been around a long time, and others here have been around a lot longer than I have, so with some luck someone will be dealing with this. I know that people have been prodded into action, so…

As long as people are careful to consider the limitations of their knowledge, even—or perhaps most importantly—general experts, it is my experience every person has the possibility of teaching someone something they didn’t know, even when the the student is an expert specialist in the field of interest.

This is often interfered with by various human tendencies, unfortunately.

 

If there is no tolerance band, i.e. only three color bands, assume 20% tolerance

GREEN BROWN YELLOW = 510kΩ ±102kΩ
ORANGE ORANGE GOLD = 3.3Ω ±0.66Ω

VIOLET RED SILVER GOLD = 0.72Ω ±0.036Ω

 

But these three aren’t solvable with the provided info:

I skimmed the text, but didn't see anything where it said you couldn't use other resources. In any case, the training material is not without its flaws.

Here's a chart from the internet that's more complete:

 

Hi, I’m studying the AAC textbook and on this page:

https://www.allaboutcircuits.com/worksheets/resistors/

Question 8 has three questions which aren’t solvable with the information given in any linked resources from the site. We’re supposed to:

“Determine the nominal resistance values of these resistors, given their band colors, and also express the allowable tolerance in ohms.

For example, a 25 kΩ resistor with a 10% tolerance rating would have an allowable tolerance of /- 2.5 kΩ.”

But these three aren’t solvable with the provided info:

Grn, Brn, Yel
Org, Org, Gld
Vio, Red, Sil, Gld

Let's follow some links on the site.

From the Homepage, follow the Education:Textbook link.
From there, follow the Direct Current (DC) link.
From there, follow the Resistance link under Ohm's Law.
Follow the resistors link in the "What is a Resistor" section.
From there, follow the resistor color code link in the "Resistor Color Code (3 - 4 Band)" section.

This page provides all of the information needed to answer the questions.



Included are some very relevant examples:

I looked around elsewhere on the internet and found that three-band resistors are 20% tolerance by default. That solves the first one. The second one requires you to know that a third metallic band is a 0.1 (G) or 0.01 (S) multiplier. Finally, the third question is still mysterious to me even though I understand how the given answer was arrived at (72 x 0.01 ±20%) because I couldn’t find a resource saying how a gold fourth band ever equal a 20% tolerance.

Unless I completely missed it in the provided and linked materials, I think including this information on-site would be better than having the student, who is a noob at this point, “figure it out for themselves” because there’s no way for us to know whether the question is a mistake, what happens in this special case when the fourth band is silver (if gold here is 20% tolerance, is silver 40% tolerance or 10% tolerance?) or when we would expect to encounter such specimens in real life. Other than that, I’m enjoying the course.

I'm at a loss as to where you are getting that the given answer for the third problem is (72 x 0.01 ±20%). The given answer is "Vio, Red, Sil, Gld = 0.72 Ω, /- 0.036 Ω", which is a 5% tolerance, as indicated by the gold tolerance band.

Note that all of the answers are missing the '+' in '+/-'.

 

I can’t edit the post but two corrections are the third question has a 5% tolerance and silver would be 10%. The calculator shows this but otherwise the info is nowhere else, including in the text on the calculator page. Thanks.

Yes, silver would be 10% -- IF the tolerance band were silver and not gold. The tolerance indicated by a gold tolerance band is 5%.

The silver band is the multiplier band, indicating a multiplier of 0.01.

 

Let's follow some links on the site.

From the Homepage, follow the Education:Textbook link.
From there, follow the Direct Current (DC) link.
From there, follow the Resistance link under Ohm's Law.
Follow the resistors link in the "What is a Resistor" section.
From there, follow the resistor color code link in the "Resistor Color Code (3 - 4 Band)" section.

This page provides all of the information needed to answer the questions.

View attachment 317390

Included are some very relevant examples:

View attachment 317389



I'm at a loss as to where you are getting that the given answer for the third problem is (72 x 0.01 ±20%). The given answer is "Vio, Red, Sil, Gld = 0.72 Ω, /- 0.036 Ω", which is a 5% tolerance, as indicated by the gold tolerance band.

Note that all of the answers are missing the '+' in '+/-'.

Thanks for finding the EE Resource link; you've disproven my premise and shown how full of resources this site is. As far as where I got the 20% instead of 5%, that's just good old fashioned bad math on my part. 5% is 1/20th and I got confused with the percents. Part of the reason I'm studying electronics is to use math in a practical way and you can see I need the practice.

Thanks for the help, everyone. I'm much clearer on resistor bands and feel more confident now that I see the EE resource pages. I think if any possibility of improvement remains for the course, maybe that link could be included on the Resistor Worksheet page. Or not . Cheers.

 

At the risk of shaking your new-found confidence, you will discover that the resistor color code (and many, many other things) are not as engraved in stone as we are led to believe. There are frustrating exceptions and deviations that you will run into. None-the-less, the basic rules serve as a firm foundation that is, far more often than not, correct.

 

At the risk of shaking your new-found confidence, you will discover that the resistor color code (and many, many other things) are not as engraved in stone as we are led to believe. There are frustrating exceptions and deviations that you will run into. None-the-less, the basic rules serve as a firm foundation that is, far more often than not, correct.

Thanks for the heads up! I’ll be sure to make good use of my multimeter once I get it.