Ohm's law
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I'm sure glad you guys didn't wire my house
So am I, I hate residential work.
I guess they teach things differently where you come from, part of impedance is reactance, which is the vertical line in the impedance triangle. The resistance is the horizontal. The hypotenuse is the resultant impedance. This is 2nd year electrician stuff where I'm from.
As I said, I never looked at a mod on a scope, I don't know what the output looks like. Now I'm truly curious though, so I will see what I can see on Monday if there's time. The PWM I deal with is, for all intents and purposes, AC. It drives AC motors, and powers other AC devices. I am far from an electronics expert, but electricity and I are old friends.
I must be a real geek at heart…I got to the last post in this thread and felt like it was a cliff hanger. Damn I gotta wait till monday
If you want to see the way various APV's react on an oscilloscope look up PBusardo's videos.
You guys are funny. I'm going to take this to my EE professor on Monday if it's not resolved.
This is 100% correct. A periodic wave is not in itself AC. A square wave DC signal is still DC, and a PWM signal is essentially a variable square wave: the amount of time in the ON or OFF position can be varied over a period, which is what is called the duty cycle.
What this means to us, is that we can control the amount of power delivered to a load, without needing to change the voltage. Replace motor in the below image with APV:
BTW, this directly applies to the "rattlesnake" effect spoke of wrt APVs. If you use a low frequency PWM signal, the length of time in each position is longer, and noticeable to us, creating the rattlesnake effect. The higher the frequency, the quicker the switching for a given duty cycle, and the less noticeable it is to us.
Note, for a given voltage, and a given duty cycle, the amount of power delivered is the same regardless of the frequency. A high frequency signal and a low frequency signal at a given duty cycle spend the same amount of time in the ON and OFF positions, the high just toggles between the two states quicker.
Also worth noting. Just because we're talking about frequency doesn't make anything magically AC, as noted above.
... I have no idea how to respond to this. Electronics are built upon electrical theory.
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And I was saying that the part we were discussing was not related to more complicated electronics, just simple electrical theory. As I said, I am not well versed in electronics.
I'll also add something about the magnetic and electric fields being discussed. They are not the same thing, by the way, but are very much related.
One way magnetic fields are caused are by moving electrical charge, current, through a conductor. In fact, current moving through a long wire is one of the simplest examples of a magnetic field being generated in this manner. So yes, we do have magnetic fields created every time we fire our APV.
Electric fields are caused by a combination of charged particles and varying magnetic fields. So if we talk about APVs with PWM in play, there are varying magnetic fields in play at all the transient points (when the signal switches from ON to OFF, or OFF to ON). This means we have electric fields.
NOTE: Electromagnetic theory is stupidly complicated. I'm not an expert, and truth be told, I had to open a couple of my old textbooks and think a little to write this, but I could still be wrong...
One way magnetic fields are caused are by moving electrical charge, current, through a conductor. In fact, current moving through a long wire is one of the simplest examples of a magnetic field being generated in this manner. So yes, we do have magnetic fields created every time we fire our APV.
Electric fields are caused by a combination of charged particles and varying magnetic fields. So if we talk about APVs with PWM in play, there are varying magnetic fields in play at all the transient points (when the signal switches from ON to OFF, or OFF to ON). This means we have electric fields.
NOTE: Electromagnetic theory is stupidly complicated. I'm not an expert, and truth be told, I had to open a couple of my old textbooks and think a little to write this, but I could still be wrong...
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Exactly.... The wave never crosses the zero axis and swings negative.
I'm a visual learner. There are calculators online and apps, but I like the Power Wheel. I switched the quadrants around for fun, but all of the formulae are still correct.
P=Power (watts)
V=Volts
R=Resistance (ohms)
I=Current (amps)
P=Power (watts)
V=Volts
R=Resistance (ohms)
I=Current (amps)
It's the Law
Yeah... And the Magnetic Field Lines look completely Different when the Wire is Straight. Verses what they look Like when the Wire is Looped like in an Atomizer Coil.
BTW - Somewhere Maxwell is Smiling for you Mentioning this.
True
The simple example I mentioned assumes an infinitely long, straight, wire. But that's only to be able to simplify the equations for learning and modelling purposes. My main point was that the magnetic field lines do exist in our APVs.With that said, I wholeheartedly approve of your attention to detail.
Absolutely. The higher the temperature, the higher the resistance. If I remember correctly, this is due to the molecules "wiggling" more as we introduce more energy, or temperate. More wiggle means there are more collisions with the moving electrons, hampering conductivity.
Temperature coefficient - Wikipedia, the free encyclopedia
True
With that said, I wholeheartedly approve of your attention to detail.
Thanks Stiiinger.
I was just Thinking about the "Right Hand Rule" and those God Awful Line Integrals when you mentioned that thing about Electrons in a Wire.
I'm a visual learner. There are calculators online and apps, but I like the Power Wheel. I switched the quadrants around for fun, but all of the formulae are still correct.
P=Power (watts)
V=Volts
R=Resistance (ohms)
I=Current (amps)
It's the Law
I see what you did there.
Don't Want to Scare anyone. But Anytime there is a Partial Derivative in something, there is Usually a Dif-EQ Lurking around the Corner.
Can't I just Smash the Button Down? And if the Hit Isn't Good Enough, make the Number on the Screen Bigger?
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