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Math Challenged.

I know I am losing it, but I want to bring it back.

I have screwed up some things. Figuring out a roll of wire, I had 95 turns of about 12" diameter. I thought pi was times radius, and that is because o f not using it. And then I thought there was 1,700+ feet in a box that came with 1,000 feet. I had forgotten to divide by 12 to get feet out of inches .

Losing it. Someone just commented on that in SED. Well I want it back.

A recent gaff was about an OP AMP circuit. Had a 10 K resistor from output to the - input. There were other 10 K resistors that fed it. At the beginni ng it completely escaped me that it iis feeding a null point and there is n o current. I should have known that offhand.

But math is a bi challenge to me. I understand some. Interpolating variable s like 12=4X3 and 12/3=4 and all that. I can also handle the 3a and 4b stuff. When they got to polynumials in school the lost me.

And now things seem to have changed. I never heard o tau before recently, a pparently it represents a change in some variable. I thought delta did that . So, what is the difference ? i have not gotten an answer I can understand anywhere.

I finally figured out something about the input impedance of a common emitt er amp stage. If the collector is tied right to the supply it is Re times h fe. I thought when there is resistance to the collector that this would cha nge, but now I think it doesn't. Looking at the curves of collector curren t it seems stable with voltage changes. That means it has no effect and und er normal condition like no clipping etc. so it is still at least close to Re times hfe.

If someone wants to help I am all ears. Because of my eyesight it is diffic ult to read and upgrade my skill set. I am hoping they can fix that and I h ave no shame taking medicaid because I DID pay taxes for many years and I r eally cannot work now.I fix stuff in the basement but not fast enough to ch arge by the hour.

So really, in this thread I intend to pose questions and hopefully get good answers. If you have the extra time of course.

The first thing is what the hell is tau exactly ?

Reply to
jurb6006
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Tau is 2 time pi or about 6.28 as pi is about 3.14.

You need to learn how to Google for simple things like this.

For a better explination.

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Reply to
Ralph Mowery

Wow, thanks. Now I see how I so misunderstood my math tutor. And the wire t hing, if I use radius instead of diameter then it is tau, why was that so d amn hard to pick up ?

My math tutor is very advanced and I find him nearly impossible to follow. I am his electronics tutor and he probably finds me the same. Granted I am only half there, but he is still in the basics and I can handle that. In ma th, he goes too far too fast. Maybe I am slow...

Thanks for the answer. I will think up more questions. Don't get floored by them.

Reply to
jurb6006

You are correct; delta is often used in math and physics to represent a change in a variable, such as the gradient of a straight line graph would be Delta Y / Delta X

It depends. Tau is often used in engineering to represent a time constant, for example:

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There are however many other uses in math and physics, for example see:

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Reply to
Gareth

We more commonly encounter Omega, which is 2*pi*the frequency of interest. It's represented by a funny looking 'w'.

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Reply to
Cursitor Doom

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** Sounds like a bit of a jerk too, tau meaning " 2pi " is NOT accepted in math and likely never will be.

Good old " pi" is all you need to know about !!

Giving double the famous ratio a new name ( one already used for other jobs mind you ) and dropping the centuries old one is ABSURD.

FYI:

A close approximation to " pi " is the ratio 22:7 = 3.1428...

A close approximation to "square root 2" is 99/70 = 1.41428...

... Phil

Reply to
Phil Allison

They invented TAU to avoid the letter Pi. It is a Greek letter, pronounced "Pe" in English mumble.

Because the Muricans and Britts cannot pronounce anything correctly.

They say "pie" stealing a piece from Grandmother's apple-pie.

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Trying to speak like a human, they inadvertently say "pee", feeling wet between their legs.

That's the whole TAU story.

w.

Reply to
Helmut Wabnig

Many Germans can't speak properly either. East of the Elbe and it's all impenetrable 'dunkeldeutsch' IME.

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Reply to
Cursitor Doom

interest. It's represented by a funny looking 'w'. "

I seem to remember that is the lower case omega, as opposed to the upper case meaning Ohms.

Reply to
jurb6006

n math and likely never will be. "

No no no, he is not the one who said it was 2 Pi. But he somehow intended t o use it for the pulleys, but I am not sure for what.

bs mind you ) and dropping the centuries old one is ABSURD. "

Radius is used in geometric formulae other than figuring circumference. It is used in the calculation of sin/cosine and a bunch of other things. I was reading up on it but gave it up because trig tables are a dime a dozen. Li ke the impedance nomograph someone posted. I saved it and haven't done the

2 pi F C thing for some time now.

It is easy enough to write 3.1416, as near as I calculated years ago IIRC w as 3.14159265135 and I am not sure about the last digit. I think 5 was a gu ess, but that is pretty accurate. (if it is that is)

Reply to
jurb6006

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** Areas and volumes, circle = pi x r squared, sphere = 4/3 pi x r cubed

It ain't broke and honours math history.

.... Phi

Reply to
Phil Allison

And sine/cosine and tangent. I was reading on how to figure that just out of curiosity but got distracted.

Reply to
jurb6006

ALT + 969 ASCII U+03C9 UTF-8

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Reply to
Explorer

Actually I would like a Alt+XXXX come to make the capital omega instead of typing out "ohms" every time. I have looked but there are 10,000 of them. There are also Alt+XXX codes, only 3 digits. I haven't explored that all that much.

Using Character map is a bunch of bullshit. Maybe I can just put one omega in an RTGF file and copy that when I want it.

For now I typo it out.

Reply to
jurb6006

Not RGTF, RTF.

Reply to
jurb6006

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