can't find 1/4 10Kresistor can i use a 1watt ?

[EBK]

In my first undergraduate Physics class, the professor banned calculators, and we had to be able to estimate square roots as we calculated everything by hand.  The tests were multiple choice, with answer choices like:
A) 3.27 m/s
B) 3.46 m/s
C) 2.97 m/s
D) none of the above.

One day, a frustrated student asked the professor why we couldn't use calculators when in the real world we'd be allowed to.

The professor gave an awesome answer to this, which was a very valuable lesson.  He said, "I've got news for you.  You are already in the real world.  Right now, your real world is my Physics class."

[wavley]

In my first undergraduate Physics class, the professor banned calculators, and we had to be able to estimate square roots as we calculated everything by hand.  The tests were multiple choice, with answer choices like:
A) 3.27 m/s
B) 3.46 m/s
C) 2.97 m/s
D) none of the above.

One day, a frustrated student asked the professor why we couldn't use calculators when in the real world we'd be allowed to.

The professor gave an awesome answer to this, which was a very valuable lesson.  He said, "I've got news for you.  You are already in the real world.  Right now, your real world is my Physics class."

Certainly, if you're doing something inherently math based you should definitely have a good handle on the basics and be able to do it by hand and I'm sure that's the lesson the professor was actually trying to teach.  It seems like the real life lesson I learn by that statement is that someone in control of your working parameters can force an arbitrary rule on you, which is also a lesson you should learn.   

I work with a lot of Astrophysicists and research engineers and I can pretty safely say "show me a physicist that says they're not using Matlab (or some other computer simulation/calculation software) and I'll show you a liar"

[PRR]

> "You wouldn't go to a job without a multimeter, why on earth would you go without a calculator"

My body can sense voltages but VERY imprecisely over a narrow range-- my built-in calculator can do many square-roots and some one/over problems closer than 50% (better than 10% with pencil).

> why anyone would need [the precision of] three resistors

Phono preamps. There is a 2-R 2-C network for a lumpy-falling response. If the values are not "correct", the response has "errors". Some people get very obsessive about this. Like a +/-0.01dB phono curve could make up for the crap on commercial LPs and the "creative" tweaks in mixing and mastering.

With 1%-series resistors it is hard to see how you could ever "need" more than two maybe three to hit your target close-enough for any audio purpose. I think Willmann just got into the problem and compiled the 2 3 and 4 R tables to be thorough.

[wavley]

> "You wouldn't go to a job without a multimeter, why on earth would you go without a calculator"

My body can sense voltages but VERY imprecisely over a narrow range-- my built-in calculator can do many square-roots and some one/over problems closer than 50% (better than 10% with pencil).

That's a pretty good point, and I'm a pretty big believer in being able to do all the common formulas by hand (or in your head), but reality is that I'm a middle age man with two jobs, a three year old, and a rock and roll youth, my calculator rarely leaves the vicinity of my meter, scope, and soldering iron 

[antonis]

E192 series overcome all the above issues..
(and you can count on 0.5% tolerance for some "intermediate" values, if you're such a circuit designer purist or just proceed to 0.1% tolerance and don't bother with series/parallel combinations anymore..)

P.S.
I'm waiting for Sir Mike (or any other reactionary fellow ) to come and ask what about if you need a high wattage specific value resistor.. 

[EBK]

E192 series overcome all the above issues..
(and you can count on 0.5% tolerance for some "intermediate" values, if you're such a circuit designer purist or just proceed to 0.1% tolerance and don't bother with series/parallel combinations anymore..)

Or, if you want fewer part drawers, you could use 20% tolerance resistors and keep measuring until you find one just right. 

[antonis]

Or, if you want fewer part drawers, you could use 20% tolerance resistors and keep measuring until you find one just right. 

And result in a dead-empty battery, 'cause the parts getting closer to their nominative value are set in another (narrower) tolerance class.. 

[EBK]

Or, if you want fewer part drawers, you could use 20% tolerance resistors and keep measuring until you find one just right. 

That should be hopeless Eric, 'cause the parts comming closer to their nominative value are set in another (tighter) tolerance class..

No, I meant if you needed something like 115k, you'd just measure your 100k pile until you found it.     (although, I wouldn't have time for such an approach, and I imagine the values would be somewhat Gaussian-distributed, making this doubly impractical)

[antonis]

Didn't anyone ever told you NOT to respond with quotation during quoted person editing.. 

If they indeed are Gaussian distributed they exhibit high-degree predictability so you can set a formula for the less actions (measurements) till goal..

P.S.
Maybe it's time to go for lunch and save myself from been a banned spammer..

[EBK]

I can go back and edit the quote if you want.  No one would ever know.... 

[duck_arse]

I can go back and edit the quote if you want.  No one would ever know.... 

if'n you did this, it might flush out one of those reactionary types antonis^* was seeking earlier.



* antonis - noted spammer, recently banned.

[GibsonGM]

What about if you need a high wattage, specific value resistor?

* I will assume being talked about means that I have 'arrived' on the social scene?   

[PRR]

> if you needed something like 115k, you'd just measure your 100k pile until you found it.

Best-case, the manufactured values are utterly random, and given a large enough barrel, you will find a 115K.

As manufacturing improved, values clustered around nominal, Gaussian trend, and parts in the crack got harder to find.

Worse than that: we didn't have sub-penny resistors, no deep barrel to sort through. Then you take a file and work-down a 100K into a 115K. Dab of nail-polish to seal the raw carbon.

[Perrow]

If you can't find a 10K ¼ watt resistor at your local store......
Find another store!

That's assuming you actually have a local store to begin with. The cheapest possibility to get hold of a 1/4W 10k resistor anywhere close to me is about $12USD, I'd get 20 each of 30 different values. Not bad looking at the total value but for the one resistor I need it's expensive and that money could buy a lot of stuff from Tayda.

I can also travel a bit (not that far but more than an hour off track as opposed to on my way home) and buy a single carbon comp resistor for about $0.1 or a metal film for $1.5. They have cheaper metal films, but not in store at the moment (estimated delivery in 11 weeks).

[antonis]

a metal film for $1.5

They probably are Uppsala Seismologiska Unstitut sole supplier..

[Perrow]

They probably are Uppsala Seismologiska Unstitut sole supplier..

That's actually probably true, they are the "go to" supplier in Sweden, they are in Stockholm though (as I am most days but not nights).

My favorite institute of Uppsala is the geological, they've promoted themselves with the slogan "Geology, the foundation of everything" which I find hilarious.

[thermionix]

Way off topic...do you know Stevie Klasson?