Dear All,

Have a nice day

This is related to resistors

I want to clearly understand how can I clearly identify E12 and E24 standard resistors by looking at color codes

Please advice

 

I don't know what a "stranded resistor" is, so you might need to provide more information.

E12 resistors are 10% tolerance, while E24 resistors are 5% tolerance. What colors will the tolerance bands be on them?

 

it has 51K and 7.5k but this two resistors are not in E12 standard



How do we recognize the 100 Ohms resistor weather it is E12 or E24

 

The value 100 occurs in all E ranges, so the value does not belong in a particular series. The tolerance shown is 5% so probably belongs in E24 on that basis.

 

View attachment 299657

it has 51K and 7.5k but this two resistors are not in E12 stranded

View attachment 299658

How do we recognize the 100 Ohms resistor weather it is E12 or E24

I still don't know what you mean by an E12 stranded resistor. Do you mean "E12 standard"?

What color is the tolerance band on those resistors?

What does that mean about the tolerance of those resistors?

Given that tolerance, are they more likely to be E12 or E24?

 

I still don't know what you mean by an E12 stranded resistor. Do you mean "E12 standard"?

Yes I corrected it thanks

Both resistors tolerance color is Gold

 

Yes I corrected it thanks

Both resistors tolerance color is Gold

So, what is the tolerance if the tolerance band is Gold?

If you don't know -- look it up. Google something like "resistor tolerance color" and look at just about any site the comes up in the results.

 

The resistors on Your photos all have a gold tolerance band. Therefore they have 5% tolerance. Since 7.5k is not a valid resistance in the E12 series, they belong to E24. The E24 series has 5% tolerance, as someone has already written. The 10% tolerance is marked by a silver tolerance band.
But: in my opinion, it doesn't matter, which series they belong to. Important are the resistance, the tolerance, temperature characteristic, the max. allowed dissipation on them and the mechanical dimensions.

 

I don't know what a "stranded resistor" is, so you might need to provide more information

A little pedantic don't you think?

 

A little pedantic don't you think?

With just the initial post, I had no idea what kind of resistor he was talking about -- there are resistor types that I have never heard of and so I didn't know if a "stranded" resistor was one of them or not. It wasn't obvious to me until his subsequent post that he almost certainly meant "standard", which is why I asked him if that was what he meant.

 

51 and 75 are both in the E24 series.

10 11 12 13 15 16 18 20 22 24 27 30 33 36 39 43 47 51 56 62 68 75 82 91

 

Thanks every one

May I ask another question

Please point out the reason the E12 standard has 12 numbers values between 0 to 10
Is there ant particular reason or mathematical approach between this 12 values

I mean

first value is 1
second valve is 1.2
Third value is 1.5 and so on

Is there any particular combination between two adjacent numbers

Please advice

 

The 10% tolerance range of each value slightly overlaps the the tolerance range of the next resistor in the series.

 

Thanks every one

May I ask another question

Please point out the reason the E12 standard has 12 numbers values between 0 to 10
Is there ant particular reason or mathematical approach between this 12 values

I mean

first value is 1
second valve is 1.2
Third value is 1.5 and so on

Is there any particular combination between two adjacent numbers

Please advice

Yes, and this is explained on numerous websites and has been explained in numerous threads on this site.

But, I'm feeling generous because I need to take a break from something else I'm working on.

Let's motivate the discussion with a somewhat whimsical example.

Say that you manufacture a resistor that is nominally 6540 Ω, but it has a tolerance of and has a tolerance of 10%. That means that the actual value could be anywhere from 5886 Ω to 7194 Ω.

Would it make any sense to also manufacture other 10% resistors that have nominal values anywhere within this range, say 6200 Ω, which would have a range from 5580 Ω to 6842 Ω.

If a customer decided that they would ideally want a resistor that was 6600 Ω, which would they choose, since either value could actually be closer to what they want (of course, in practice, they would pick the 6540 Ω resistor because it would be more likely to be closer to the 6600 Ω than a 6200 Ω resistor would, but it might not). Even worse, in many situations you would not want to pick up a resistor marked 6540 Ω and discover that it actually had less resistance than one that was marked 6200 Ω. Yet, with 10% tolerance, this is not only possible, but actually fairly likely. So, instead, you want to space the nominal resistance values far enough apart so that there is little, if any, overlap between their ranges.

But if you spread them too far apart, so that there is a sizeable gap between their possible range of values, then you make it so that a customer that needs a particular value and is willing to "bin" the parts by measuring the actual values and choosing the ones that are acceptable, will be unable to find such a resistor because the value they need falls within the gap.

So, ideally, you want to space adjacent resistor values so that their tolerance ranges just touch.

Let's say that R0 is one of your values and R1 is the next value up. Now let's say that 'tol' is the tolerance -- for 10%, tol=0.1.

We want the top of R0's tolerance range, which is given by R0(1+tol), to be equal to the bottom of R1's tolerance range, which is given by R1(1-tol).

R0(1+tol) = R1(1-tol)

This means that we want the ratio of successive resistor values to be

R1/R0 = (1+tol)/(1-tol) = k

So

R1 = k·R0

What would the next value up, namely R2, be?

R2 = k·R1 = k·(k·R0) = k²·R0

Following this reasoning,

R3 = k^3 · R0

Rn = k^n · R0

For convenience, it would be nice to have R0 be something "nice", like 100 Ω. Similarly, it would be nice to have 1000 Ω in our list (as well as 10 Ω and 10 kΩ and so forth).

So how many values do we have in one decade (i.e., going up in resistance by a factor of 10), given a particular tolerance?

We want

Rn = 10 · R0 = k^n · R0

This means we want

10 = k^n

Taking the common log of both sides, we have

log(10) = n · log(k)

Since log(10) = 1, this means we have

n = 1 / log(k) = 1 / log( (1+tol)/(1-tol) )

For tol = 0.1, this results in n = 11.47.

So we have two choices. We can set n = 11 and have gaps, or we can set n = 12 and have overlaps. There's pros and cons either way.

But what if tol = 5%? Then we ideally have n = 23.01,

At the time that this was worked out, most resistors were actually 20% tolerance and many were even 50% tolerance. So the n values for those are

50%: n = 2.10
20%: n = 5.68
10%: n = 11.47
5%: n = 23.01

If we round each of these up, and thereby accept that we will have overlap between adjacent values, we have

50%: n = 3
20%: n = 6
10%: n = 12
5%: n = 24

So the number of values doubles for each successively tighter tolerance. This also turns out to make it easy to keep all of the values from one tolerance group for the next "better" group and fill it out by just putting a standard resistor value as close to the geometric mean of the two neighbors as possible.

If you look at the actual values in the various sequences, they are very close to those that this mathematical derivation suggests. There are only a couple of places where the choice made doesn't quite match up. I've looked for explanations behind why these "oddball" choices were made and have never found any -- it's very likely that the decision was based on choosing a particular widely used common value over the slightly different "correct" value, but the true reason is likely lost to history.

 

The 10% tolerance range of each value slightly overlaps the the tolerance range of the next resistor in the series.

Very clear Thanks

Could you please explain this 10% tolerance and forth band ( GOLD 5% tolerance ) combination

Thanks in advanced

 

If the 4th band is gold, the tolerance is 5%. If it's silver, it's 10%.

For example, 100 ohms is a standard value in E6 (20%), E12 (10%), E24 (5%), E48 (2%), E96 (1%) and E192 (0.5%) classes. You can find 100 ohm resistors in each class, with the tolerance indicated by the colored band.

A 100 ohm E6 resistor may fall anywhere between 80 and 120 ohms, while an E96 100 ohm resistor will be between 99 and 101 ohms. What the acceptable range is depends on the resistors function in a circuit.

As a practical matter, higher precision resistors are cheap these days – 1% resistors are common and don't cost much more than lower class resistors.

 

If the 4th band is gold, the tolerance is 5%. If it's silver, it's 10%.

For example, 100 ohms is a standard value in E6 (20%), E12 (10%), E24 (5%), E48 (2%), E96 (1%) and E192 (0.5%) classes. You can find 100 ohm resistors in each class, with the tolerance indicated by the colored band.

A 100 ohm E6 resistor may fall anywhere between 80 and 120 ohms, while an E96 100 ohm resistor will be between 99 and 101 ohms. What the acceptable range is depends on the resistors function in a circuit.

As a practical matter, higher precision resistors are cheap these days – 1% resistors are common and don't cost much more than lower class resistors.

View attachment 299763View attachment 299764

if resistor is E12 (10%) and 4th band is gold( 5%) then what is the actual value of 100 Ohms resistor

the E12 standard says value of 100 Ohms resistor 90 to 110 then what is the 5%

 

95 to 105 ohms..is 5% tolerance for 100 ohms.
So the smaller the tolerance is the best.

 

if resistor is E12 (10%) and 4th band is gold( 5%) then what is the actual value of 100 Ohms resistor

the E12 standard says value of 100 Ohms resistor 90 to 110 then what is the 5%

No, you're misunderstanding.
For example, you can get a 100 Ohm resistor in any of the E standard ranges from E12 onwards, as you can for a 120 Ohm resistor, because it falls within the 10% or better tolerance. But you can't get a 110 Ohm resistor in the E12 range, only in the E24 or higher ranges, because it would fall within 5% or better of the other 2 resistors. And so on up the tolerance scale.

 

If you buy a "100 ohm" resistor, it is nominally 100 ohms. But chances are remote that it's exactly 100.000 ohms because of tolerances in materials and manufacturing. The resistance varies with temperature too.

If the "100 ohm" resistor has a silver band, it's within the range of 100 phms plus or minus 10%. 10% of 100 = 10, so the resistor is within the range of (100 — 10) to (100 + 10) or 90 – 110 ohms.

If the "100 ohm" resistor has a gold band, it's within the range of 100 phms plus or minus 5%. % of 100 = 5, so the resistor is within the range of (100 — 5) to (100 + 5) or 95 – 105 ohms.

In most circuits, having a resistor of an exact value isn't important.