AC THEORY

[PaulMmn]

That's a good point too, in that a lot of computer programs do the heavy lifting that engineers from 50 years ago had to do manually.

...and with a slide rule accurate to 3, maybe 4 digits. And you kept track of the exponent yourself!

 

[PaulMmn]

I know what harmonics are... But if it makes you feel better....
P.s., any finger can produce it, its a thing called postion just so ya know...
Just about any instrument can produce harmonics, btw, not just a violin.... Including wind and brass instruments. Saying "violin" is like saying "i googled it and educated somebody".

I agree-- but violinists poke at a string to get the harmonic they want!

 

[rambojoe]

I agree-- but violinists poke at a string to get the harmonic they want!

No. They do it many ways. Same as any stringed instrument. Stop... Itll make you a better man...

 

[rambojoe]

I do apologize for that last reaction... Uncalled for in the education section.
It does remind me of someone here telling me why moto racers drag their knee through the turns though... I do know me some instruments though.

 

[LarryFine]

It does remind me of someone here telling me why moto racers drag their knee through the turns though...

I know why. My present stable:

 

[zbang]

Larry, not as much of a knee-dragger as my Daytona .

 

[Joethemechanic]

I'm old and I don't ride so fast anymore. And yeah I hate the paint job too, started redoing it for this year before I messed up my ankle

 

[Strathead]

I know what harmonics are... But if it makes you feel better....
P.s., any finger can produce it, its a thing called postion just so ya know...
Just about any instrument can produce harmonics, btw, not just a violin.... Including wind and brass instruments. Saying "violin" is like saying "i googled it and educated somebody"..

Well I question that. Are you telling me you can't play any note on a violin in two different octaves? Also, I am unaware of ANY natural sound producer that produce a single, clean tone. The timbre of any instrument is made up of the various harmonics, and subtones that are unique to that instrument. So, a violin definitely produces harmonics. In at least two ways.

 

[rambojoe]

Well I question that. Are you telling me you can't play any note on a violin in two different octaves? Also, I am unaware of ANY natural sound producer that produce a single, clean tone. The timbre of any instrument is made up of the various harmonics, and subtones that are unique to that instrument. So, a violin definitely produces harmonics. In at least two ways.

What exactly are you talking about? Please re-read what i wrote and post#83, cite what you dont understand and ill try to help.

 

[drcampbell]

... I am unaware of ANY natural sound producer that produce a single, clean tone. ...

An oboe is pretty close.

A very early synthesizer, the Gooch Synthetic Woodwind, was so named because pure electronic tones ended up sounding like one.

 

[Strathead]

An oboe is pretty close.

A very early synthesizer, the Gooch Synthetic Woodwind, was so named because pure electronic tones ended up sounding like one.

I'll buy the Oboe, just because I don't really know the overtones. The synthesizer is the epitome of NOT natural .

 

[Therealcrt]

You keep having the same misunderstandings.

This is true.
TE = 1/2*m*v^2 + 1/2*k*x^2

This is where you've introduced terms without any reason, and begun to make your false conclusion:
TE = 1/2*m*v^2*cos(theta) + 1/2*k*x^2*i*sin(theta)

Neither component of total energy should ever go negative in this situation. KE can't be negative, since rest is the slowest it can move. By convention of letting PE equal zero at x=0, the lowest PE can also be is zero. So it doesn't make sense to just multiply them by cos(theta) and i*sin(theta) like you have done.

This is how you really should approach what you are trying to do.
x(t) = A*sin(w*t)
v(t) = A*w*cos(w*t)

The known general solutions for x as a function of time, and its derivative, v as a function of time. A is amplitude and w is angular frequency. You can make A & w both equal to 1 for simplicity, but I'll keep them for the general case.

Take these equations, and substitute them in to the equation for each form of energy:
PE = 1/2*k*x^2
PE = 1/2*k*(A*sin(w*t))^2
PE = 1/2*k*A^2*sin(w*t)^2
sin(w*t)^2 = 1/2 - 1/2*cos(2*w*t)
PE = 1/4*k*A^2*(1 + cos(2*w*t))

KE = 1/2*m*v^2
KE = 1/2*m*(A*w*cos(w*t))^2
KE = 1/2*m*A^2*w*cos(w*t)^2
cos(w*t)^2 = 1/2 + 1/2*cos(2*w*t)
KE = 1/4*m*A^2*w^2*(1 + cos(2*w*t)

Using the standard known solution that w^2 = k/m, we can see that:
KE = 1/4*k*A^2*(1 + cos(2*w*t))

Neither of these energy values are ever negative, or imaginary. These both are based on cosine functions of time that always add up to the same total energy (TE = 1/2*k*A^2), but not at the same frequency as the original functions x(t) and v(t), and they are not centered on zero.

My point exactly.. unless you want to be an electrical instructor why would a journeyman or master electrician really ever need to know this crap

 

[Carultch]

My point exactly.. unless you want to be an electrical instructor why would a journeyman or master electrician really ever need to know this crap

Troubleshooting is reason. You may be able to follow a plan set without understanding the theory behind it, as long as things are going well. But when things go wrong, and you need to locate the problem, that is where understanding the theory comes in handy. Understanding how to connect symptoms with their causes and solutions. It also helps to understand theory when the plan set specifies a nuanced approach to a particular situation. I've seen phase balancing ignored, when I've specified it and code-compliance depends on it.

You probably don't need to know the math behind why the solution to an LRC circuit works the way it does, but being able to identify the properties of AC waveforms in a scope, and know what amplitude/phase/frequency all mean, is something all of us should know how to do.

 

[Sberry]

AC waveforms in a scope, and know what amplitude/phase/frequency all mean, is something all of us should know how to do.

Not me,,, I got this guy,,, also winding a tranny using record player turntable and bunch of other junk, If I had to understand that we would still be in the dark.

 

[Besoeker3]

A bit of what I did in my third or fourth year.......................

 

[Sberry]

Go ahead, remind me I am still eating dirt.

 

[PaulMmn]

At least you were building up your immune system!

 

[Sberry]

I thought this thread was going to be about air conditioning.

 

[Dsg319]

I thought this thread was going to be about air conditioning.

If they had a heat pump theory we’d be cookin.

 

[acin]

I think you are right that you can install electrical components and perform a decent amount of troubleshooting without knowing AC theory. But knowing it will make you a better troubleshooter and give you confidence. Plus less likely to put your foot in your mouth.
Plus, if you start to get bored with just doing the basics, knowing theory can give you a boost in branching off into another area of the industry.
And you can tell your guys not to use an extension cord while it is coiled up because of inductive reactance will cause it to heat up.
It all boils down to what you want to do with your life and if you're happy with the status quo.
If it were me, I would learn everything I could about my industry. That way when my body can't do the work anymore, I can use my expertise to continue working using my knowledge instead of my back.

dont the 2 wires in the extension cord cancel each other out . thinking of a transformer winding being one conductor