Resistor Sizes Vary Greatly?

[tggzzz]

I'm in favour of making students realise that.you can't buy a resistor, but can buy something that is a combination of inductor plus capacitor plus resistor. Then do a little analysis to determine where typical poles and zeros will occur.

I'm not in favour of getting students to think too deeply about polystyrene caps advantages over teflon capacitors - except where it is critical to experimental apparatus they are using.

If you teach the characteristics of MLCC caps, what are you going to omit? What's the half-life of such knowledge? University should teach fundamentals that will last a lifetime. If they understand fundamentals, they will be applicable to whatever they encounter in the future. That won't happen with knowledge of the C-vs-V characteristics of CapCon's current products.

A well balanced degree course teaches mostly strategic knowledge to keep you useful in the long term, sprinkled with a broadly useful mix of tactical knowledge to make you useful in the short term.
Things lots of people struggle with for many hours are excellent candidates for that tactical knowledge area, where they can be made useful in an hour or two.

I would modify that to say the degree should give you the wisdom to know where your knowledge/experience is inadequate, and then to know how to learn what you need to know next.[1] That learning will take several lifetimes

Tactical knowledge is fine and useful, but if that's all somebody knows, they will waste time on blind alleys and things which are known to be impossible. That happen especially often with software, of course.

[1] Professor Eric Laithwaite at Imperial College used to set exams where one question was easy and sufficient get you a pass mark, one was more challenging and could get you a good degree, and one could not be answered adequately in the time available. He expected his undergraduate engineers to be able to determine which questions to avoid. If they couldn't, they wouldn't make good engineers anyway. I doubt he would be allowed to do that now, more's the pity.

[coppice]

I would modify that to say the degree should give you the wisdom to know where your knowledge/experience is inadequate, and then to know how to learn what you need to know next.[1] That learning will take several lifetimes

You expect people to gain wisdom out of a degree course? You have extremely high goals. I'm happy if they just acquire a reasonable amount of understanding, and not just how to answer questions like a parrot.

[tggzzz]

I would modify that to say the degree should give you the wisdom to know where your knowledge/experience is inadequate, and then to know how to learn what you need to know next.[1] That learning will take several lifetimes

You expect people to gain wisdom out of a degree course? You have extremely high goals. I'm happy if they just acquire a reasonable amount of understanding, and not just how to answer questions like a parrot.

Yes, I do - within the limit I described. If they can't, then they aren't fit to go on to be an engineer.
So did Professor Eric Laithwaite at Imperial College.

Just because 50% of youth get degrees whereas only 10% of youth got degrees when I was young, doesn't mean the definition of a good degree has changed.

I, and a few friends (one a member here ), went back to our university on its open day, for our <mumble>th anniversary of graduation. I'm pleased to say that the students we spoke to and the university course they described seems to have exactly the same ethos as when we were there.

[shapirus]

Yes, I do - within the limit I described. If they can't, then they aren't fit to go on to be an engineer.
So did Professor Eric Laithwaite at Imperial College.

That's perfectly right, as long as we're talking about engineers, as in, people whose profession is to design things (and be paid for this). Engineers must have respective education, or experience and skills that can effectively serve as its substitution (and are required in addition to education anyway).

However, there's a lot of variants, in terms of possessed and required (expected) knowledge and skills between a beginner hobbyist and a professional engineer. And I guess in this topic and in this section of the forum we're more in the context of the former than of the latter.

[Jwillis]

I don't know how these can be equivalent.  The Chinese ones are even supposed to have a 5% tolerance.
- Wil

The smaller Chinese one is a Yageo.
The tolerances only mean that the true values of the resistor will be within plus or minus the coded values.
Both the larger resistor and smaller resistor can have similar characteristics But the test qualifications can be different.
The smaller resistor has an IEC (International Electrotechnical Commission) standard bases on those test set out by the IEC.
The larger resistor has a Mil (Department of Defence) qualification. Which tend to be far more stringent than the IEC. The construction and dimensions will be based on those tests set out by the department of defence. If you want to dive down that rabbit hole, all the  power to you.

Body colours of resistors and inductors can be different depending on the manufacturer and series. There is no standard body colour for either. You must read the datatsheet for the component from the manufacturer that produced it.

For general purpose, standard metal film , carbon composite and /or ceramic cement will work just fine in most applications. Check that the voltage rating of the resistor is acceptable for the voltages you will be using. Usually the voltage rating of a resistor should be double the operational voltage. As long as the rated voltage is higher than the applied voltage plus any possible spikes in voltage.
There is no rule, other than space restrictions, that dictates that a higher power resistor can't replace a lower power resistor.
Smaller resistors of the same power rating as larger ones will dissipate heat over a smaller area. So the "Real Feel'' will be hotter on a smaller resistor than an equivalent larger one. This temperature won't effect the resistor in it's self, by may effect components near it. So give small hot resistors they space they need or change it to a larger one.

The main requirements when choosing a resistor is the Value, Power, Voltage, Stability(temperature coefficient) and cost. 

[tggzzz]

Yes, I do - within the limit I described. If they can't, then they aren't fit to go on to be an engineer.
So did Professor Eric Laithwaite at Imperial College.

That's perfectly right, as long as we're talking about engineers, as in, people whose profession is to design things (and be paid for this). Engineers must have respective education, or experience and skills that can effectively serve as its substitution (and are required in addition to education anyway).

However, there's a lot of variants, in terms of possessed and required (expected) knowledge and skills between a beginner hobbyist and a professional engineer. And I guess in this topic and in this section of the forum we're more in the context of the former than of the latter.

I agree, but I will note these points...

My comments were in the context of coppice's posts which include (the traditional) "thread drift".

My attitude to "technician vs engineer" is the same as "nurse vs doctor": they are complementary, with different advantages, both are necessary, neither is sufficient. Vive la difference!

I do strongly object to anybody that thinks nurses are "better" (in some poorly defined way) than doctors. Ditto technicans being better than engineers.

The relevance to a beginner is that they may not appreciate the differences - and knowing the differences may help them choose the foundation for the rest of their career.

[coppice]

I would modify that to say the degree should give you the wisdom to know where your knowledge/experience is inadequate, and then to know how to learn what you need to know next.[1] That learning will take several lifetimes

You expect people to gain wisdom out of a degree course? You have extremely high goals. I'm happy if they just acquire a reasonable amount of understanding, and not just how to answer questions like a parrot.

Yes, I do - within the limit I described. If they can't, then they aren't fit to go on to be an engineer.
So did Professor Eric Laithwaite at Imperial College.

Just because 50% of youth get degrees whereas only 10% of youth got degrees when I was young, doesn't mean the definition of a good degree has changed.

I, and a few friends (one a member here ), went back to our university on its open day, for our <mumble>th anniversary of graduation. I'm pleased to say that the students we spoke to and the university course they described seems to have exactly the same ethos as when we were there.

We must be using different dictionaries. You can teach engineering. You can't teach wisdom. Some of the most capable engineering minds have no wisdom at all. We need to make use of their engineering skills, and keep them well away from decision making.

Its delusional to think that degrees have not changed. In the UK we used to leave high school at 18 having studied the material in a US bachelor course. Now a UK bachelor degree is no higher in standard than a US degree.

When I was at university, UCL had about 7,500 students and was the largest single college in the UK. I think Imperial was about half that size. Now UCL has 43,000 and Imperial 20,000. Together they are not much smaller than the total UK university student population when I studied. Less than 10% of youngsters took A levels, and far more of those went on to things like day release and evening classes than full time study at a university. You really think they have been able to expand universities from taking 3% of state school leavers and a similar number from the public schools and maintain similar standard?

[tggzzz]

I would modify that to say the degree should give you the wisdom to know where your knowledge/experience is inadequate, and then to know how to learn what you need to know next.[1] That learning will take several lifetimes

You expect people to gain wisdom out of a degree course? You have extremely high goals. I'm happy if they just acquire a reasonable amount of understanding, and not just how to answer questions like a parrot.

Yes, I do - within the limit I described. If they can't, then they aren't fit to go on to be an engineer.
So did Professor Eric Laithwaite at Imperial College.

Just because 50% of youth get degrees whereas only 10% of youth got degrees when I was young, doesn't mean the definition of a good degree has changed.

I, and a few friends (one a member here ), went back to our university on its open day, for our <mumble>th anniversary of graduation. I'm pleased to say that the students we spoke to and the university course they described seems to have exactly the same ethos as when we were there.

We must be using different dictionaries. You can teach engineering. You can't teach wisdom.

Yes, we must be.

This is as good a definition as any, and it can be taught. "the ability to use your knowledge and experience to make good decisions and judgments"
https://dictionary.cambridge.org/dictionary/english/wisdom
Most people will learn something from such teachings, but there are always people that can't/won't learn.

Some of the most capable engineering minds have no wisdom at all. We need to make use of their engineering skills, and keep them well away from decision making.

I have no idea what you are thinking there; it makes no sense to me.

Having engineering skills requires having good judgement (and good taste ).

It could be argued that technicians have less need for judgement, since they follow pre-defined procedures. I wouldn't make that argument, since a good technician is capable of doing that and more.

[coppice]

We must be using different dictionaries. You can teach engineering. You can't teach wisdom.

Yes, we must be.

This is as good a definition as any, and it can be taught. "the ability to use your knowledge and experience to make good decisions and judgments"
https://dictionary.cambridge.org/dictionary/english/wisdom
Most people will learn something from such teachings, but there are always people that can't/won't learn.

Some of the most capable engineering minds have no wisdom at all. We need to make use of their engineering skills, and keep them well away from decision making.

I have no idea what you are thinking there; it makes no sense to me.

Having engineering skills requires having good judgement (and good taste ).

It could be argued that technicians have less need for judgement, since they follow pre-defined procedures. I wouldn't make that argument, since a good technician is capable of doing that and more.

You can't teach good judgement. You can talk through the unintended outcomes of narrowly focussed thinking, that ignored the big picture, and make people better aware of the value of good judgement. Good luck trying to teach it, though. Its a quality of a person's character, like critical thinking. Another area of utterly failed experiments in teaching.

[Siwastaja]

You can't teach good judgement. You can talk through the unintended outcomes of narrowly focussed thinking, that ignored the big picture, and make people better aware of the value of good judgement. Good luck trying to teach it, though. Its a quality of a person's character, like critical thinking. Another area of utterly failed experiments in teaching.

It's not either-or. If a person is totally incapable of critical thinking, maybe it's too late trying to educate this after kindergarten / few first primary school years, but there surely are people who have mixed traits and it's pretty important to nudge them a bit into the right direction. We should be able to define our values, and tell people what matters in engineering. We should also give examples, and while at it, use real-world examples because then they double as direct transfer of information. You can't teach every technical detail like that, but if you choose well which details you teach, they work as examples of higher level concepts.

[coppice]

You can't teach good judgement. You can talk through the unintended outcomes of narrowly focussed thinking, that ignored the big picture, and make people better aware of the value of good judgement. Good luck trying to teach it, though. Its a quality of a person's character, like critical thinking. Another area of utterly failed experiments in teaching.

It's not either-or. If a person is totally incapable of critical thinking, maybe it's too late trying to educate this after kindergarten / few first primary school years, but there surely are people who have mixed traits and it's pretty important to nudge them a bit into the right direction. We should be able to define our values, and tell people what matters in engineering. We should also give examples, and while at it, use real-world examples because then they double as direct transfer of information. You can't teach every technical detail like that, but if you choose well which details you teach, they work as examples of higher level concepts.

I don't think there is much research about wisdom, but there has been about critical thinking. Obviously its not a black and white ability you either have or lack, but nobody has succeeded in training to improve it. Various weak studies have thought they had found improvements, then people who applied more critical thinking to those studies found the subjects had simply been trained with analytical responses to the particular topics they had been taught. They had gained no generalised ability to analyse. This is really sad. Most things are very much a combination of nature and nurture. You can't turn an idiot into a genius through education, but you can add a few points to their IQ score, and that can be enough to make a considerable difference to their life outcome. There is no sign you can go anything about critical thinking.

[Bud]

You can't teach good judgement. You can talk through the unintended outcomes of narrowly focussed thinking, that ignored the big picture, and make people better aware of the value of good judgement. Good luck trying to teach it, though. Its a quality of a person's character, like critical thinking.

I am with coppice on this one. Especially on the "big picture" statement, which requires the mind qualities which many of the perfect tech engineers lack.

[tggzzz]

You can't teach good judgement. You can talk through the unintended outcomes of narrowly focussed thinking, that ignored the big picture, and make people better aware of the value of good judgement. Good luck trying to teach it, though. Its a quality of a person's character, like critical thinking.

I am with coppice on this one. Especially on the "big picture" statement, which requires the mind qualities which many of the perfect tech engineers lack.

A perfect engineer never loses sight of the big picture. Engineers know their objective is to drain the swamp, not to kill alligators.

If something cannot be taught, then the only alternative is that it must be genetic. 

Siwastaja's statements are nuanced and, I believe, pretty accurate. Attitudes can be inhaled when young, and can be taught by example when older. Having said that, nobody could have taught me to be a fast runner, nor high jumper, nor...

[coppice]

Siwastaja's statements are nuanced and, I believe, pretty accurate. Attitudes can be inhaled when young, and can be taught by example when older. Having said that, nobody could have taught me to be a fast runner, nor high jumper, nor...

There goes that dictionary issue again. Your "nuanced and accurate" seems to equate to my "wishful thinking, unsupported by evidence". The inelastic nature of many human traits has always been hard for many people to accept. "You can be anything" is such BS. Most people have to accept reality when a 1.7 metre tall teenager thinks they can be the next Michael Jordan, but ignore it when reality isn't fully rubbed in their face.

[Siwastaja]

"You can be anything" is such BS.

Of course it is, but nobody suggested that. You are creating a strawman. From personal experience, I can easily remember university teachers and later bosses who really nudged me into the right direction (and I mean attitude and engineering process), and those who just tried to transfer information with not much success. It is natural to human to copy behavior from the surroundings, trying to adapt to the culture. This is why the voting behavior can be easily manipulated by just telling them "how others will vote", so that they will vote for the assumed winner, instead of discussing the values of the parties/representatives and choosing one that matches their values.

Similarly, you can tell students to learn to question, let's say, credibility of appnotes (T3sl4c01ls pet peeve), and show an example of a misleading / plain wrong information on an appnote, and explain why and how it is wrong - do it well and the students remember it for the rest of their lives, and some, those capable of it, would be more prone to apply similar thinking to other appnotes.

No scientific proof of such behavior? Bummer. Either you didn't look too hard, or it doesn't exist, but absence of proof is not proof of absence. It is sometimes surprising how little we have studied human behavior, or even psychology. You can find much more scientific studies from animals because the tests are so much easier to arrange.

[tggzzz]

"You can be anything" is such BS.

Of course it is, but nobody suggested that. You are creating a strawman. From personal experience, I can easily remember university teachers and later bosses who really nudged me into the right direction (and I mean attitude and engineering process), and those who just tried to transfer information with not much success.
...
Similarly, you can tell students to learn to question, let's say, credibility of appnotes (T3sl4c01ls pet peeve), and show an example of a misleading / plain wrong information on an appnote, and explain why and how it is wrong - do it well and the students remember it for the rest of their lives, and some, those capable of it, would be more prone to apply similar thinking to other appnotes.
...
but absence of proof is not proof of absence.

Yes indeed.

My presumption would be that those that those who are not "capable of it" would never make good engineers. They might be very productive in other roles, of course.

Too often people fall into the trap of "I can't do it therefore it can't be done", or "I can do it therefore you can/should do it".

As an illustration of the unspoken "I can't do it therefore it can't be done", I well remember an anecdote in the wonderful book "Most Secret War" (aka "Wizard War") by RV Jones about his experiences in Scientific Intelligence in WW2. Jones was gathering evidence about a new powerful unknown rocket weapon (later known as the V2), and the UK scientific experts said the intelligence should be discounted because it was theoretically impossible. When it became obvious how it was being achieved, those experts said "ah, yes, liquid fuel, didn't think of that".

[coppice]

"You can be anything" is such BS.

Of course it is, but nobody suggested that. You are creating a strawman. From personal experience, I can easily remember university teachers and later bosses who really nudged me into the right direction (and I mean attitude and engineering process), and those who just tried to transfer information with not much success. It is natural to human to copy behavior from the surroundings, trying to adapt to the culture. This is why the voting behavior can be easily manipulated by just telling them "how others will vote", so that they will vote for the assumed winner, instead of discussing the values of the parties/representatives and choosing one that matches their values.

Huge numbers of people love the mantra that you can be anything you want. Its pervasive through society these days, even though most people realise its rubbish. As you said, most people will go along with rubbish rather than point it out. When I was young the mantra was more to find your strengths and play to them. The change has been quite destructive.

Similarly, you can tell students to learn to question, let's say, credibility of appnotes (T3sl4c01ls pet peeve), and show an example of a misleading / plain wrong information on an appnote, and explain why and how it is wrong - do it well and the students remember it for the rest of their lives, and some, those capable of it, would be more prone to apply similar thinking to other appnotes.

Have you ever followed some people who don't question things enough and see how they behave over a reasonably long time? Most of them will spend ages struggling over something., eventually figure it out, and say "well, I won't fall for that again". Not too long later they do. The interesting thing is if you point this out they generally cannot see the similarity of the two situations, while the good critical thinkers around them easily can. You can train people to parrot better behaviour in exactly repeating situations, but can you make them do it when the situation is even a little different. Research says no.

No scientific proof of such behavior? Bummer. Either you didn't look too hard, or it doesn't exist, but absence of proof is not proof of absence. It is sometimes surprising how little we have studied human behavior, or even psychology. You can find much more scientific studies from animals because the tests are so much easier to arrange.

There has been research. Its rather dismal, so people try to play it down.

[tggzzz]

Huge numbers of people love the mantra that you can be anything you want. Its pervasive through society these days, even though most people realise its rubbish. As you said, most people will go along with rubbish rather than point it out. When I was young the mantra was more to find your strengths and play to them. The change has been quite destructive.

When I was young the zeitgeist was more along the lines of accepting your place in the hierarchy and deferring to those with better breeding.

Both are demoralising and destructive when applied without thinking about exceptions - as such things always are.

[coppice]

Huge numbers of people love the mantra that you can be anything you want. Its pervasive through society these days, even though most people realise its rubbish. As you said, most people will go along with rubbish rather than point it out. When I was young the mantra was more to find your strengths and play to them. The change has been quite destructive.

When I was young the zeitgeist was more along the lines of accepting your place in the hierarchy and deferring to those with better breeding.

Both are demoralising and destructive when applied without thinking about exceptions - as such things always are.

That has ebbed and flowed in the UK. When I grew up in the 1960s I expected by adult life to be massively constrained by my working class origins. However, things opened up as Britain realised that to maintain industrial power it needed talent wherever they could get it from. I was easily able to get into a top tier university merely by being in the top 1% of school results. Then Britain gave up being a first world power, and the class base for society became strong again. Where were you on that time line?

[tggzzz]

Huge numbers of people love the mantra that you can be anything you want. Its pervasive through society these days, even though most people realise its rubbish. As you said, most people will go along with rubbish rather than point it out. When I was young the mantra was more to find your strengths and play to them. The change has been quite destructive.

When I was young the zeitgeist was more along the lines of accepting your place in the hierarchy and deferring to those with better breeding.

Both are demoralising and destructive when applied without thinking about exceptions - as such things always are.

That has ebbed and flowed in the UK. When I grew up in the 1960s I expected by adult life to be massively constrained by my working class origins. However, things opened up as Britain realised that to maintain industrial power it needed talent wherever they could get it from. I was easily able to get into a top tier university merely by being in the top 1% of school results. Then Britain gave up being a first world power, and the class base for society became strong again. Where were you on that time line?

Similar.

My father was a chemical engineer, so I never conceived that being an engineer wasn't possible. The grammar school vs secondary modern divide was more of an issue.

As for me, I got a scholarship to a local public school, but elected to go to the local grammar school. Never had any cause to regret that, was using the darkroom and their scopes in my lunchtime, and reclaiming transistors and passives from a stock of scrap boards in a cupboard. Everybody took maths and English Lang O-levels a year early, and I wasn't the only one with 5 STEM A-levels, too (one was a duplicate of two others).

[Wil_Bloodworth]

This topic is about resistor sizes and how size compares to power dissipation.  While the topic of education certainly has merit, it does not belong in this topic and this topic has been driven off the rails.  Please create a new thread to discuss this further.  Thank you!

- Wil

[tggzzz]

This topic is about resistor sizes and how size compares to power dissipation.  While the topic of education certainly has merit, it does not belong in this topic and this topic has been driven off the rails.  Please create a new thread to discuss this further.  Thank you!

Thread drift has been happening for the past 40 years, and will continue indefinitely.

Let us know if you manage to prevent it.

[coppice]

This topic is about resistor sizes and how size compares to power dissipation.  While the topic of education certainly has merit, it does not belong in this topic and this topic has been driven off the rails.  Please create a new thread to discuss this further.  Thank you!

Thread drift has been happening for the past 40 years, and will continue indefinitely.

Let us know if you manage to prevent it.

Thread drift is a looming threat.

[Zero999]

This topic is about resistor sizes and how size compares to power dissipation.  While the topic of education certainly has merit, it does not belong in this topic and this topic has been driven off the rails.  Please create a new thread to discuss this further.  Thank you!

- Wil

A better way to deal with a thread going off-topic is to post something to bring it back on course.

Do you have any further questions relating to the the original topic?

[BILLPOD]

This topic is about resistor sizes and how size compares to power dissipation.