Electronics > Beginners
Started a MOOC, is trig and calc really necessary a beginner DC circuits class?
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rstofer:
You go nowhere in engineering without a TON of math.  The sooner you make friends with it the better.
There are online tutorials that deal with theory and math.  Khan Academy Electrical Engineering and Digilent's "Real Analog" series are pretty good.

Even in DC circuits, and I mean strictly DC, no switches, no capacitors, no inductors, solving resistor mesh problems and calculating internal resistance and maximum power transfer takes a lot of matrix math.  Kirchhoff's Laws were made to sell matrix algebra.

Given the realities of engineering and math, it's best to get comfortable with a solver.  MATLAB (Home Edition) is my favorite (it costs money plus an annual fee) but GNU Octave will do the same things but possibly not with the same syntax and it's free.  Working through some of my grandson's Physics problems, I often pull up MATLAB and enter the known relationships and calculating results as I go along.  I use MATLAB like a calculator with a file system for recall.

You will really need something when you get more than 3 loop or node equations.  Solving 4x4 matrices is not fun and beyond that point they are a real drag.  Yes, I know how Gauss-Jordan elimination works.  I grew up in the era of slide rules.

AC Circuits is all sin() and cos() functions and the trig identities will be necessary.  Oh, and f(t) kinds of things like the capacitor charging equation vo=vs(1-e(t/RC))

Derivatives and integrals of trig functions will be all over the place.
jmelson:

--- Quote from: Ronan on April 11, 2019, 05:58:48 pm ---So I started Georgia Institute of Technology's MOOC on Linear Circuits 1: DC Analysis https://www.coursera.org/learn/linear-circuits-dcanalysis/home/welcome, presumably it's the most beginner level course I could find (before starting the edX MIT 3 course series).

--- End quote ---

For strictly DC circuits, no.  But, that will only last for about a week, then you move on to transient circuits, which is the domain your question is in.
Then, trig does come in, and just a small bit of calculus.

Jon
rstofer:

--- Quote from: Ronan on April 11, 2019, 09:56:06 pm ---
--- Quote from: rstofer on April 11, 2019, 09:48:41 pm ---Yes, the first problem is definitely AC but it's not all that deep because, the way I read it, they want the instantaneous power at t=4.

The first part is just 'plug and crunch' to find that the argument to cos() is 240*pi which is the same as cos(0) which is 1.  7 times 1 => 7 Amps.  Figuring out power = voltage * current is now pretty easy.

The second part looks like you have to take a derivative but,in reality, you figure out that since the cos(240*pi) is 1, the slope at that point is 0 so di/dt= 0 and 5 * 0 is still 0.  The voltage is 0 so the instantaneous power is 0.

Here's a couple of hints:
www.symbolab.com  == solving just about everything
www.desmos.com     == graphing

I sure hope I got that stuff right...

--- End quote ---

You have no idea how this helps me! Thanks. It gives me something to review, with the problem so I can understand it. There was zero trig in the course (at this point) and zero explanation of how the problems were solved, so your little input here does wonders. Thanks!!

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Wait until somebody agrees before you take my word for it.  It was nice that it broke down to cos(0) because that really simplifies things.
rstofer:

--- Quote from: jmelson on April 11, 2019, 10:08:27 pm ---
--- Quote from: Ronan on April 11, 2019, 05:58:48 pm ---So I started Georgia Institute of Technology's MOOC on Linear Circuits 1: DC Analysis https://www.coursera.org/learn/linear-circuits-dcanalysis/home/welcome, presumably it's the most beginner level course I could find (before starting the edX MIT 3 course series).

--- End quote ---

For strictly DC circuits, no.  But, that will only last for about a week, then you move on to transient circuits, which is the domain your question is in.
Then, trig does come in, and just a small bit of calculus.

Jon

--- End quote ---

True, strictly DC means batteries and resistors.  After explaining and demonstrating Kirchhoff's Laws (node and mesh equations), Norton, Thevenin and superposition, what's left to talk about?  Next up is a capacitor and a switch.  Then the arithmetic gets a little more involved with ln(x) and ex.
westfw:
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it's the most beginner level course I could find
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Look for classes aimed at getting you a ham radio license...
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The first part is just 'plug and crunch'
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Yes.Quote
  to find that the argument to cos() is 240*pi which is the same as cos(0) which is 1.
--- End quote ---
But that requires knowing some trig.Quote
The second part looks like you have to take a derivative but ... since the cos(240*pi) is 1, the slope at that point is 0
--- End quote ---
And realizing that requires knowing some trig AND some calc.
ie, they're "easy trick questions", but only if  you know the tricks."sin(60*pi*t)" is home AC, more or less, so perhaps the questions are relevant outside of "signal processing."
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