It was only an innocuous and tongue-in-cheek comment, an attempt to lighten up a heavy thread, but apparently you have to become upset at everyone.
MrAl,
[Ratchet in reply to:] "So in short, we're taking two different physical starting conditions and two different time lines."
I don't see the relationship between viewpoints and starting points of time lines with respect to whether a device is voltage or current controlled.
<snip because it's the same thing said before>
Ratch
... Voltage alone implies the availability of energy and charge, for otherwise, voltage cannot be defined ...
This is an incorrect statement. Feel free to respond if you feel I'm misunderstanding what you are trying to say here, but here is my logic.
A 1 pF capacitor charged to 3.16 V has 3.16 pC of charge and 5 pJ of energy.
A 1000 F supercapacitor charged to 3.16 V has 3160 C of charge and 5 kJ of energy.
These are two devices I can order on-line, receive them in one day and charge up in my lab. Once I do that, they differ in both energy and charge by 15 orders of magnitude !
So voltage does not imply the availablity of either energy or charge.
And, voltage can be defined without any problem.
It represents the potential energy that a hypothetical test charge (a small charge that does not disturb the fields) will have in the existing electric field.
More formally, it is the line integral of electric field for a test charge as it moves between two points in an electric field.
So, we are able to define and even measure voltage with a test charge with the most minimal amount of charge. There is the practical matter of just how small it can be, but in principle it can be very very small.
Now we can ask the question, which capacitor might be more useful to bias and control a transistor? Obviously one capacitor does not have the energy or charge to affect the device at all, and the other might very well blow it up in a puff of smoke, if we are not careful.
...So i think you should change your sig line to "Hopelessly Disagreeable"
So to iterate and summarize. You cannot have voltage without energy and charge. That is basic to specifying a concentration of energy per unit charge. The fact that the electrical energy source cannot sustain the voltage does not abrogate that fact.
Ratch
To me this lends support to MrAl's viewpoint because if voltage really controlled anything alone, then any lone amount of finite charge and energy (no matter how small) would control and operate the device as long as it generated a voltage. But the capacitor example shows that voltage alone is not enough.
In any event, since you place a high value on pedantics, I felt obligated to allow you to clarify your statement, because it struck me as an inaccurate statement without further explanation.
You said my example was inacccurate before, but I do not see how your example disproved what I said about voltage controlling a device.
If you had said "Voltage alone implies the existence of energy and charge", or "Voltage alone implies the presence of energy and charge", I would not have been confused by the meaning. But, "Voltage alone implies the availability of energy and charge" can be interpreted to mean that the voltage can supply the energy and charge, as needed.
steveB,
I agree with what you are saying. I should have made clear that voltage control also requires that the voltage will be sustained at a satisfactory level.
Ratch
Ratchet:
"I should have made clear that voltage control also requires that the voltage will be sustained at a satisfactory level"
You just voided your original statement whether you realize it or not. When you get down to basic physics you have to account for every little thing. Originally you said it was the voltage that did it, but now you add a conditional to that voltage, "sustained". So you've changed it from a single requirement:
1. Voltage
to the new requirement that now requires two things:
1. Voltage
2. Sustained
Now ask yourself what that voltage needs in order to be 'sustained'. Answer: current. So another way to state this is simply:
1. Voltage
2. Current
or more simply:
1. Energy
But Steve's nice example of the two capacitors should have put a lid on this already. I dont think it could be any clearer than that because we start with two finite amounts of energy both with the same terminal voltage, yet only one "operates" or "controls" the transistor while the other one can not. So that's a clear example how the voltage doesnt matter it's the energy available that matters. The voltage does not represent nor imply the "total" energy thus it doesnt make sense to say that voltage controls anything.
The reason this paints a better picture is because the capacitors help to spell out the dynamics of the device to be controlled, while voltage alone can only describe the statics. We cant only care about the statics, we have to look well into the dynamics of the device in order to know how to control it. I tried to introduce the dynamics into the discussion when i brought up the time line. Looking at the device over time as the signals are applied helps to identify all of the concepts involved not just some.
So to recap, to get a sustained voltage we need current and another way of saying this is simply that we need energy, but also knowing the voltage isnt good enough.
Ok well then it's nice to hear that you found a 100 percent efficient diode or transistor somewhere. You should patent that thing right away.
I on the other hand am using real world devices that are not 100 percent efficient. When something requires energy that is power so it's clear to see you're just playing with words now...good luck with that.
Since you're just going to disagree with this too, i'll wait to see if Steve has anything else to add before i reply again if i do at all. The art of the debate is not simply a constant disagreement with anything and everything that is said that is contrary to your own opinion. That just leads to very uninteresting conversation.
How does that tie into a semiconductor being a voltage controlled device?
I thought you knew everything,...
...but now you are confused..
I think misterT's comment was sarcasm...misterT,
A lot perhaps, but not everything. Whatever gave you that belief?
Not confused, but without knowledge of how MrAl's link relates to voltage control of semiconductors. There is a difference between lack of knowledge and confusion. Perhaps, since you appear to know what the link means, you could elucidate.
Ratch
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?