1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Understanding Electronics Basics #2

Discussion in 'General Electronics Chat' started by cowboybob, Mar 26, 2012.

  1. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    So what do mean when you say differences:
    Approx = to
    & the exact answer if they are saying the same thing?
     
  2. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    That's what I meant, I'm getting lost in definitions but it made sense to me, I was pressing 5 (X2 button) *3 on calc

    Can see now it is 5 sq *3 = 75 then needs sqrt = answer above

    But I can see how your getting your answer now
     
    Last edited: Apr 3, 2012
  3. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

    Joined:
    Oct 30, 2010
    Messages:
    9,917
    Likes:
    1,098
    To mathematicians 3.14159 is not ∏. 3.14159 is good enough for engineers, but not for mathematicians.

    Mathematicians don't generally see decimals (e.g. 0.99 ). They have their blinders on. They see 99/100.
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England

    So which is right?
     
  6. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

    Joined:
    Oct 30, 2010
    Messages:
    9,917
    Likes:
    1,098
    It depends if your an engineer or a mathematician.
     
  7. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    Neither, I just want to learn electronics, so where does that leave me, surely if EE are using minute numbers they need decimals?
    Think I'm prob more confused now than before, sorry, I know you are trying to help me
     
  8. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    So I'm now on post #12, third link, I'm getting there, it is all leading to knowing what sine/cosine & tangent are/mean :)
     
  9. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

    Joined:
    Oct 30, 2010
    Messages:
    9,917
    Likes:
    1,098
    You ran across the 8√3 when solving for a right triangle relationship of c^2 = a^2 + a^2. We got off on a "tangent" because you had never seen the 8√3 form before. Instead of just concentrating where the 8√3 came from we diverged a bit. In studying right triangles later,you ran into the √3.

    The right triangle is fundamental to the relationships of the angles and the sides. It's fundamental to the circle, sine, cosine and tangent functions.
     
  10. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    Yeah, sorry it's so long winded but I've never done anything like this before, once I have the understanding, things should get easier as I see it accounts for all the measurements, I just want to understand it :)

    Night both
     
  11. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    Ok, you've probably guessed I'm struggling with this, don't know why as there are pictures? But for all the pictures & sohcahtoa theory, they don't actually put the sine etc to them


    Am I right in thinking if we had a sloping bank & i wanted to measure the slope at the bottom of it in degrees:
    sine = bottom (ground level)
    Cosine = height at back of bank
    Tangent = slope

    No complicated answers please, just trying to relate names to lines :)
     
    Last edited: Apr 4, 2012
  12. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

    Joined:
    Oct 30, 2010
    Messages:
    9,917
    Likes:
    1,098
    No:

    bottom (ground level)
    height at back of bank
    sloped line is known as the hypontenuse

    Now let's say your looking up a hill and we'll call the bottom angle θb because that's the angle we are interested in in this case. θb = Theta @ bottom

    So, if we were interested in that angle θb.
    the "bottom" would be known as the "Adjacent side" and the "back" would be known as the "opposite side".

    If we were interested in the angle at the top of the hill, call it θt, the meanings of "opposite" and "adjacent" would switch.
     
    Last edited: Apr 4, 2012
  13. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

    Joined:
    Oct 30, 2010
    Messages:
    9,917
    Likes:
    1,098
    The sine, cosine and tangent is just the ratio of the sides defined by the angle.
     
  14. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    Now your seeing what I can't relate to, what do you mean by the ratio?
    I didn't watch that vid because I thought I missed something because they suddenly added degrees
     
  15. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    So are you saying I've been trying to relate it to lines & it is giving us......it has to relate to the missing line for the length of it doesn't it? Hence we can calculate degree of slope

    Are we saying the same thing in different language here?

    O/H = sine, that's right isn't it?

    That has to be right, but then how is the length of sine converted to degrees?
     
    Last edited: Apr 4, 2012
  16. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    Doh, it's not the missing line, it both lines divided (corners) ignore me
     
    Last edited: Apr 5, 2012
  17. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

    Joined:
    Oct 30, 2010
    Messages:
    9,917
    Likes:
    1,098
    sin(θ) = Opposite/Adjacent (Sine = Oscar Had); So it's nothing more than the ratio of the two sides defined by the angle.

    If you happen to know the ratio of the two sides, there are inverse finctions called arcsin(), arctan() and arctan() and it can tell you the angle as long as the triangle is a "right triangle" (i.e. has a 90 degree angle)
     
    Last edited: Apr 4, 2012
    • Like Like x 1
  18. cowboybob

    cowboybob Well-Known Member Most Helpful Member

    Joined:
    Oct 22, 2011
    Messages:
    3,025
    Likes:
    477
    Location:
    James Island, SC
    Think of the gear ratios in your bike:

    For 4[SUP]th[/SUP] gear (and I'm making this up) lets say the gear ratio is 4 to 1, in other words, for one, single rotation of the crankshaft, 4[SUP]th[/SUP] gear transfers 4 rotations to the rear axle.

    Another way to state that ratio is by the fraction 4/1 (read it as 4 to 1), or 4, or 400% (all these can be done on the calculator).

    At the other end, for 1[SUP]st[/SUP] gear, with a ratio of 1 to 4, it would be the exact opposite (4 rotations of the crank shaft to 1 rotation of the wheel), or a ratio of 1/4, or 0.25, or 25%.

    For right triangles, sin(q) = opposite / hypotenuse, or the sine is the ratio of length of the opposite (vertical) leg divided by the length of the hypotenuse (the sloping part).

    That "ratio" number (as a decimal) can be converted to an angle between the two lines that composed of the bottom line of the triangle and the hypotenuse, at the point where they meet.

    Think I've got this right...

    <EDIT> Another thought: A ratio is used to express a difference between two items that are related (gears in a transmission, lines and angles that make up a triangle, people who vote for or against an issue). If there are no difference(s), the ratio is 1; any difference at all and the ratio is either more, or less, than 1.
     
    Last edited: Apr 4, 2012
    • Like Like x 1
  19. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

    Joined:
    Oct 30, 2010
    Messages:
    9,917
    Likes:
    1,098
    The circumferance of a circle is C = ∏d or Pi * the diameter. Re-writing, ∏ = C/d; the the circumference to the diameter of any circle (Ratio) is the value ∏.

    When mixing 1 bag of quickrock (cement) to 1 gallon of water when you set your fence posts. That is a ratio.
    1 bag Cement/1 gal water

    Mixing oil for a two cycle chain saw or lawn mower might be 50:1; 50 parts gasoline to 1 part oil.
     
    • Like Like x 1
  20. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    Morning KISS, you not sleeping again? & thanks both for the plain explanation of ratios :)

    I'll watch the next vid & see what I understand, sure there will be more questions, I can see clearly that I'm lacking in quite basic math when I look at sites, I have started another sub folder for definitions just for math as a reminder, this mountain keeps getting higher but the view keeps getting better :)
     
  21. Muttley600

    Muttley600 New Member

    Joined:
    Jan 16, 2012
    Messages:
    681
    Likes:
    5
    Location:
    Worcestershire, England
    I've just watched this, the missing bit I couldn't understand how we were getting degrees [​IMG]

    which is great, I can move forward again now, what is the manual way to do the same thing?

    ok, I finally understand sine/cosine & tangent [​IMG] don't get hopeful though as I still need to relate it link 4 in post #12, but I'm dead chuffed with myself [​IMG]

    Honesty is admitting the reality.......I really struggled trying to read the whole story, but by breaking it down & trusting you will show me the next paragraph, I finally absorbed what I needed to, still a long way to go but enjoying it

    Going to have a break & cut the lawn now as I feel like I've just overcome a big hurdle
     
    Last edited: Apr 5, 2012

Share This Page