My resistor question(s) thread.

[MDC]

I''ve been studying a tutorial about resistor values. I have a chart of the 9 main colours. Plus some understanding of the representations of the gold & silver rings. Also, 'the 4th ring' being a tolerence percentage ring.

Initiallly I was understanding that the 3 main rings for example would always be at one end, and anything else at the opposite end of the resistor. Then I came by a resistor that does not fit the pattern as explained. Basically it has a brown ring on each shoulder (end bits) and 3 standard rings in the centre.

Can someone enlighten me please?

 

[Nigel Goodwin]

It's a 1% resistor, so the tolerance band is brown, and you have an extra band for the greatly improved range of values. The same applies to 2% resistors, except the tolerance band is red.

You must have been studying a REALLY old tutorial, as pretty well all resistors have been 1% or 2% for a considerable time now.

From a practical point of view such resistors are extremely hard to read, as it's difficult to know which end is which - so I keep the resistors in packets, or labelled draws, and have a component tester to hand.

 

[MDC]

The resistor is one I salvaged from something,

Resistors Colour Code Tutorial & Circuits - Resistance Color Coding - Electronic Components Tutorials - Hobby Projects

Resistors Colour Code Tutorial & Circuits - Electronic Resistor/Resistance Component Color Coding - Ignore the colour of the resistor body. Most resistors have three coloured bands close together at one end and one single band at the other. The three adjacent band give the resistor value.

www.hobbyprojects.com

The tutorial was this ^^^

 

[danadak]

Regards, Dana.

 

[MDC]

danadak
I've seen the tolerance figures, but not seen the letters A to D etc in brackets - end column before. I wonder what those letters represent?

 

[danadak]

Looks like just a letter grade and its corresponding percentage.


Regards, Dana

 

[AnalogKid]

You must have been studying a REALLY old tutorial, as pretty well all resistors have been 1% or 2% for a considerable time now.

Granted that 1% and 2% parts have gotten much more popular since they quit costing 10x a 5% part, but "pretty well all"? Gotta disagree.

Digi-Key, a huge American distributor, has over 72,000 individual part numbers for SMT 5% parts, and over 65,000 for through-hole parts.

In-stock, the numbers drop to over 15,000 and almost 11,000. No matter what the percentage of all resistor sales is, that's a ***bunch*** of parts.

ak

 

[MDC]

danadak
I really like that 4 band code picture that you put up for me-it is nice and bright. A good size and easy to understand, thank you.

 

[danadak]

Then there is this one -

Regards, Dana.

 

[danadak]

And we have this -

Regards, Dana.

 

[MDC]

Excellent photo Dana- a lot quicker than a written explanation.

 

[MDC]

I'm taking screen shots of the pictures/diagrams as they are valuable to my learning. Hope they are not copyright

 

[MDC]

Am I correct to say that brown rings specifically have two fuctions? In position one the brown ring represents a value of 1, and in positon 6 it becomes the temp ? Or, could it have also been another ring colour fulfilling those two functions?

 

[danadak]

Sadly the colors, I find, are even hard to figure out what color they are on actuakl
parts. Unlike the old IRC color bands which were distinct, high contrast.

The 6 band code seems to indicate answer of yes to your first ques in post #13.


Regards, Dana.

 

[AnalogKid]

A continuing problem is that brown and red are much more difficult to differentiate on a blue background than on a tan background. With the tan body, sometimes a yellow band almost disappears, but it never causes an orientation problem.

ak

 

[MDC]

AnalogKid
I'm currently finding that this 40x magnifier is helpful. It has a light too. May not help when ring colour is a similar colour to backgound.

 

[Nigel Goodwin]

A continuing problem is that brown and red are much more difficult to differentiate on a blue background than on a tan background. With the tan body, sometimes a yellow band almost disappears, but it never causes an orientation problem.

ak

Hence why I mentioned above using a component tester on any not in packets, or in labelled draws - even worse the packets don't always have the values on, just the order code

Older 5% and 10% (even 20%) resistors were easy to red, had good bright colours and a nice contrasting background, but the modern 1% and 2% ones are terrible.

 

[MDC]

I didn't realise that resistors could be tested when not in a circuit.

 

[JimB]

I didn't realise that resistors could be tested when not in a circuit.

When any component is connected in a circuit to other components, there will often be some effect from the other components on the one which you are trying to measure.

Often the only way to accurately measure a component is to remove it from the circuit. This is often done by simply disconnecting one end of the component from the circuit.

JimB

 

[AnalogKid]

I didn't realise that resistors could be tested when not in a circuit.

That is actually the best way to get a true reading. In a circuit it is connected to other stuff, and that stuff almost always creates a small sneak current path across the resistor. Might not be much, and might disappear when the test probes are reversed, but it's always there. Ot of a circuit, the only thing you have to be careful about is not touching both ohmmeter probes with bare skin. The body is an excellent sneak current path that can ruin the reading of a high-value resistor.

ak