Steve Nosko said:
long post warning directed at Ratch...
Hi there Ratch. Comments inserted below, but I am using terminology that
has been used for a long time and is commonly accepted. If the OP has
problems, I prefer him to pose (sp) the questions for clarification.
Much of what you point out is right along the lines of the following
examples.
ROM stands for "Read Only Memory", right?
RAM stands for "Random Access Memory", right?
Yet ROM is also "Random Access". Therefore, ROM IS RAM. These are
conventions which came about by an imperfect system of terminology. Namely,
whatever sticks gets used.
Yes, ROM can also be RAM. The two attributes are not mutually
exclusive.
Example closer to this:
Does a "river flow"? Do you know what this means? I think you do, yet by
your comment a river is a flow of watter and "a river flows" would be
"incorrect". We could only say that "Water Flows".
"A river flows" is a rather poetic description. If the Army Corps of
Engineers installed a flow meter in a river, would they label it "river
flow", "water flow", or "rate of flow?"
While I appreciate youre desire to be correct, I do not believe the OP would
be confused by my use of very common terminilogy and if he/she is, then the
questions will come from them/he/she.
Probably not be confused, but one never knows.
I would, however, ask that you comment on the concepts in question. Is it
an explanation of *WHY* the coupling cap causes the Veb to go negative
causing no conduction in the part?
The original question scrolled out of my message buffer. I only have
some of the replies, including yours.
Ratch said:
Steve Nosko said:
[...snippity snip...]
On the first positive peak, some current flows through the base
Current does not flow. Current IS flow.
I agree (in a manner of speaking) that changing this to:
" some charge flows through the base emitter junction"
is "correct", but I maintain that it is _just as
understandable_.
However, if I really wanted to use the word, current, how would you word
it? What does current do when it does its thing? Since "flow" is included
in the term "current", would I say:
" On the first pulse, some current happens through base emitter junction." ?
We don't talk that way.
You could say "some current exists through ...".
Certainly it is. However, the point is that the capacitor develops a
potential difference across its two terminals because of the difference of
charge between the two sides. I maintain that my use is common usage in the
field. I agree that I could have said:
"The current is some quantity of electrons per time, right."
I believe that either way, the following sentence would provide the
necessary train of thought.
I can easily guess what you mean. Perhaps a better way is to say "The
current brings/deposits a quantity of electrons
...."
capacitor...
Then you say:
It is completely common to refer to "charging a capacitor". You will
probably be very surprised that we also refer to "charging an incuctor".
This use of the word "charge" no longer refers to electron charge (in both
cases), though that is where the term originated. This "charge" is a
generic term meaning, perhaps, to "impart come analog quantity", or "fill
with some desired substance" which can be electrons, magnetic field, or
Halon. Just like we may say to "charge a battery" or "charge" one of those
glow-in-the-dark things by holding it near a strong light, then turning off
the light to watch it glow brightly. Although we commonly "load" a spring,
we could also use this convention ( though unconventional for a spring) and
charge it in some situation. We "charge" fire extinguishers, but no current
flows there eigher and we "charge" gasoline at the pump. Still no
electrons. It's common usage which may be imperfect, but accepted and
understood as a result.
"Charge" is used in electronics as either a noun or a verb. I shun
using it as a verb in electronics because it can be
confusing. It is surprising how many nubes think that charging a battery or
a cap means filling it up with electrical charges
so they can be removed and used later. The word "energize" is more
descriptive. There is no problem in using "charge" with respect
to filling a gas tank or using a credit card. This is because we are not
adding/removing "charges" on these items. Furthermore, unlike a cap, we are
actually increaing/decreasing their net quantity of gas or credit.
Going in to depth on a capacitor, you say...
While this is a detailed description of what may be some of the
properties of electric charge and the capacitor, I did not believe that
going down to this level of information helps understand how the Base bias
goes negative in the target circuit. The operation of the capacitor is a
lower level concept which I was hoping the OP had some understanding of. If
not, then more detail of capacitors would be evident from the OP's
follow-up.
Your hope is probably justified. I was explaining why I thought a cap
should be thought of as energized.
I'll do what I accuse you of doing and see how you respond.
I have to give the statement "net change of charge is zero for a
capacitor going from zero volts to its breakdown voltage" some analysis.
First, I don't think capacitors "go" anywhere when we drive electrons
onto one side. (do they sit in the back seat or front?)
Neither, they mill about smartly.
Second, I could argue that there is a *change* of charge because there
are more electrons on one of the capacitor foils than the other...but that's
another thread. I'm just trying to reenforce my point that our use of
terminology is imperfect, but in some circles it is accepted.
I agree with both sentences above.
Oh yes, I don't believe electrons "like" or "dislike" anything... I
don't think they can. They do, however, appear to have a repelling force
when brought near each other.
Yes, that is more technically correct.
Whether or not the net charge changes, we certainly have rearranged that
charge such that there is one hell of a potential differennce between the
capacitor plates. That is the point.
Indeed, the charge is imbalanced.
Gee, do modern capacitors have "plates" any more... so...what do I call
these things, eh?
I believe they do, whether they are folded, interleaved, rolled, or
bifuracted, they can still be analyzed as a sandwitch
with a dielectric filling.
We "energize" circuits and light bulbs. Does that mean that there must be
some stored charge differential, as in a capacitor, in order for us to use
that term?
No, the word energize means to imbue energy to something. We can create
a electrostaic field in a capacitor, or
a electromagnetic field in a coil, or dissipate heat and maybe light by
creating a current through a resistor. Either way the
circuit is energized.
...Didn't see any more of your comments...
I maintain that it is common and acceptable for:
current to flow.
Capacitors to charge and discharge.
Yes, and many folks think that R=V/I is Ohm's law, which it is not.
Ohm's law refers to the resistive linearity of a
material, not the resistance formula. But everyone first thinks of that
formula when you say "Ohm's law".
By the way, even though *you* also use some of this imperfect terminology, I
know precisely what you **mean** when you say:
"for a capacitor going from zero volts to its breakdown voltage" - don't
go anywhere
I should have been more descriptive and said "its voltage value goes
from ..."
"charge stored on one plate" - no plates in many a common cap these
No plates or their equivalent? What then?
days
"they do not like to get close together" - what other emotions do
electrons have...
Yes, I should have said they repel each other. I was giving the
electrons anthropic properties they did not deserve.
The point of the thread is:
If I replace all of my terms with yours, will the explanation then tell the
OP why the inductor is needed ??
Only the OP can answer that one.
One of worse descriptive phrases comes from NASA when they refer to
their astronauts as "space walking." Everyone
knows what they mean, and all can see that they are floating or drifting,
not walking. I always wanted to ask NASA what would
happen if their tethers separated. Would the astros walk away, or float
away from their ship? I liked it better when they
referred to that activity as EVA. Walking in space to me means walking on a
structure in space wearing sticky boots. Ratch
