difference between bipolar and mosfet

[Kevin Aylward]

John Fields wrote:

On Wed, 12 Jan 2005 08:06:17 GMT, "Kevin Aylward"



that _current_ being what causes the collector
current to flow.

NO! NO! NO!. Absolutly not. You are wrong. It is not the flow of
charge in the base that *causes* collecter current. This has already
been explained in many posts.

Charge flows because of:

F=q(E+vxB)

That is, excluding magnetic effects, it is *Electric Fields* that
make chages move. Period. The flow of charge, excluding magnetic
effects, cannot make other charge flow, other then by the change in
electric field that such flow might cause.

---
I said that the flow of charge between the emitter and base causes
charge to flow between the emitter and collector,

Indeed you did.

and you say that's
wrong because the flow of charge between the emitter and base causes
charge to flow between the emitter and collector

No I didn't. I specifically denied that. I said the *ELECTRIC FIELD*
between the base and emitter causes charge to flow from emitter to the
base region.

*THE FLOW OF CHARGE BETWEEN EMITTER AND BASE DOES NOT CAUSE THE FLOW OF
CHARGE BETWEEN EMITTER AND COLLECTOR*

I can't say it any plainer.

[because the flow of
charge between the emitter and base causes the electric field between
the emitter and collector to be changed to the point where charge can
flow between the emitter and collector.]

Now where was I wrong, exactly?

All of the above. I repeat what I said here.

"Applying an *electric field* to the base emitter
injects carriers from the emitter into the base region. Once the
carriers are in the base region, they are attracted by the *electric
field* of the collector and are swept up (collected) by the collector
due to this *electric field*. Some of the emitter carriers just don't
make it, and are picked up via the base terminal. This base current is
an *effect* not a cause, and is incidental to the base emitter *electric
field* injecting carriers."

*Nowhere* does this claim that the flow of charge causes another flow of
charge.

---

For the umpteenth time. Applying an *electric field* to the base


If it weren't for the base current there would be no collector
current, so it _is_ a cause,

Not at all. A correlation does not have to be causal. This is basic 101
statistics.

For example, suppose those that have cats have less stress, should we
recommend that people get cats? Or is it that less stressed people
simply have a side effect of liking cats.

regardless of what's causing _it_ to
happen.

No. This is why the tobacco industry had a legal claim against smoking
causing cancer. It might be that those more likely to get cancer also
had a side effect of just wanting to smoke.

One needs to show that a correlation is *actually* causal. In this case,
it is Vbe that causes both collector current and base current. Base
current does not cause the collector current, but it is correlated.

---

To repeat, it is not the *motion* of base charge that *causes* the
*motion* of collector/emitter charge. It is the electric field at Vbe
that causes both base current and collector/emitter current, as it
is, now get this 101 physics, *ELECTRIC FIELDS THAT MAKE CHARGES
MOVE*. End of story. Period.

---
I don't disagree with that.

Your argument above says that you do disagree.

---

---
If that's true, then a BJT isn't a transconductance device because
the collector current isn't a _direct_ consequence of the
base-emitter voltage, it's once removed since the _direct_
consequence of the base-emitter voltage is the base-emitter current.

No. This shows that base current is an effect, of an electric field
cause.

---
Again, I don't disagree with that.

Your argument above says that you do disagree.

And this is all wrong. I have already explained, a continuous
resistance would mean that the base is connected to that resistance,
hence, no transister action.

---
I don't know why you keep claiming that I said that the thing is a
slab of of either P or N type material, when what I said was that it
starts to _look_ like that between the collector and emitter when base
current starts flowing.

Because this analogy must account for the fact that there is a direct
connection from the base to the emitter.

Much like the region between the cathode and
the plate of a vacuum tube starts to look like a resistor when the
tube is conducting. Is there a resistor between the plate and the
cathode? No. Does it _look_ like there is? Yes.

Its not like the tube. The tube has no connection from grid to cathode
or anode.

---

Quite frankly, as noted above, you simply don't understand how a
bipolar transistor works. Read and understand the above. Its the way
it is. I can tell you that if you gave this description in an
academic semiconductor physics class, you would get a zero grade.

---
Perhaps, but since this is sci.electronics.basic, a rigorous treatment
of the matter is seldom apropos. In this instance, a simple reply to
the OP (which, BTW, you said you had no problem with) and some
analogies which you either misunderstood or decided to take issue with
for your own reasons seems to have led us up to where we now sit.

I, for one, no longer have the desire to continue with this
"discussion", so I'll excuse myself and bid you good day.

Fair enough.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[John Fields]

On Fri, 14 Jan 2005 13:26:42 -0800, Jamie
<jamie_5_not_valid_after_5_Please@charter.net> wrote:

John Fields wrote:

On Thu, 13 Jan 2005 22:41:02 GMT, Miles Harris <mazzer@yahoo.com
wrote:


On Thu, 13 Jan 2005 13:05:07 -0800, Jamie
jamie_5_not_valid_after_5_Please@charter.net> wrote:



thats ok, i am enjoying it!

Put it out of your mind as a pointless distraction, sonny and get
stuck back into your textbooks. Head down and study, study, study is
the only realistic way to success.


---
Hogwash.

All work and no play is _not_ a good thing.

how's it going John.. see your having a nice day )
keep up the good work.!

---
Well, it's a dirty job, but _somebody_ has to do it...

--
John Fields

 

[Miles Harris]

On Sat, 08 Jan 2005 11:11:22 -0600, John Fields
<jfields@austininstruments.com> wrote:

The application of a forward voltage to the base-emitter junction of a
bipolar transistor will, of course, cause charge to flow between the
collector and emitter, but the movement of charges across the
base-emitter junction _is_ relevant, since without that movement there
can be no collector current.

Yes, but that's misleading. It's essential to concentrate on the
relationship between the applied voltage to the base/emitter junction
and the resultant collector current. The BJT is a transconductance
device and should be viewed as such.

In a MOSFET, however, the only movement of charge required to control
the drain-source current is that required to charge and discharge the
gate capacitance.

Correct. The time it takes to perform this charge/discharge cycle
dictates the maximum useable frequency of the FET.

 

[John Popelish]

Skeleton Man wrote:

so if I'm to understand correctly.. a bi-polar will pass current between
collector and emitter when a voltage is applied to the base ?

The important detail you are missing in this description
is that the base voltage must be with respect to the emitter.
Not all uses of bipolar junction transistors hold the emitter
at a fixed voltage, so you have to keep the emitter voltage in mind
when you are thinking about whether a particular base voltage change
will turn the emitter to collector current up or down.
The base to emitter path is also a diode junction, so the applied
voltage will also have to deal with forward biased diode current.

...and a fet will do
a simmilar thing only doesn't require a current ? (at whichever terminal
corresponds to a base on a bipolar)

Yes. The gate corresponds to the BJT's base. But it is insulated
either by a reverse biased junction (in junction fets) or by an
insulating layer (usually silicon dioxide in Metal (gate) insulated by
Oxide on Silicon fets otherwise known as mosfets ). Again, it is the
gate to source voltage that controls the conductivity of the drain to
source path. Even though the gate is insulated, it forms a plate of a
capacitor, so if you want to turn a fet on or off very quickly, you
may have to deal with a considerable capacitive current during the
voltage swing. In general, fets take a larger gate to source voltage
change (several to more than 10) to make the channel conductivity
swing from non conducting to full conduction than BJTs do (less than 1
volt).

--
John Popelish

 

[Jamie]

Skeleton Man wrote:

so if I'm to understand correctly.. a bi-polar will pass current between
collector and emitter when a voltage is applied to the base ? and a fet will do
a simmilar thing only doesn't require a current ? (at whichever terminal
corresponds to a base on a bipolar)

Regards,
Chris


to break it down in a simple manner.

Bi-polar requires a minimum voltage to over come the
the cut off effects of the Be (Base-Emitter) just like a diode
would do. this on the average around 0.6 and varies on different
voltage and styles of bi-polar. once you reach the break over point
current starts the flow in the Be, that is if you have the emitter
connected to an end point to cause current to build other wise all you
get is the voltage past through the Be. if you were to put a voltmeter
on the E and Current meter (I) in series with C (collector), with no
load on the E, you can see the measured voltage that is being applied
to B-theBreakdownPoint of BE, this is the same effect as passing lets
say 12.0 through a diode and resulting in 11.4 on the average.
you will notice that very little to no current will show in the meter.
as soon as you apply a load on the E, current will develop and this
acts like a current bridge allowing the C (collector) to flow over it.
the end results of current is the ratio between base current and
Collector current which is many times referred to as Hfe. which means
in short for example, 10 Ma Be, will cause 100 ma Ce if the Hfe is 10
keep in mind that Bi-polar are not linear devices, temp and current
windows in the BE will effect the range. they make nice simple thermo
devices to be used in a temp gauge

-----
FET's
are more like static bridges.
the Drain+Source are like a field resistor that required a field of
electrons to create a conductive path much like the tubes of yester
years. the gate applies this field of voltage and the only current you
may see is the initial charge of capacitance that exist in that gate
section. once charged, the a mount of current is very low to maintain
the set point. just think of charging a cap.
that is why high freq FET's are tricky to design, must keep the
Cap low while still trying to get the effect.
FETS are good for Bi-switches, good linear range, has much less
effects with ambient temps and very populer where Hi-Z is required
to convert Very low voltage and current gerating devices to a use able
bi-polar conversion.
for example a Type J thermo couple where the generated current is
so low that using Bi-polar is not very good but the FET is perfect.
using a ceramic mic where capactance veraition is used.
etc..

with out getting into to much biasing details etc, i think i may have
explain it well enough..

 

[John Fields]

On Sun, 09 Jan 2005 14:31:59 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On Sat, 08 Jan 2005 11:11:22 -0600, John Fields
jfields@austininstruments.com> wrote:

The application of a forward voltage to the base-emitter junction of a
bipolar transistor will, of course, cause charge to flow between the
collector and emitter, but the movement of charges across the
base-emitter junction _is_ relevant, since without that movement there
can be no collector current.

Yes, but that's misleading. It's essential to concentrate on the
relationship between the applied voltage to the base/emitter junction
and the resultant collector current. The BJT is a transconductance
device and should be viewed as such.

---
It's only a transconductance device because of the voltage required to
force charge through the base-to-emitter diode, that charge changing
the electrical properties of the base material to more closely
approximate those of the collector and emitter. That is, when charge
is injected into the base-to-emitter diode of a PNP transistor, the
"N" type base material becomes more and more "P" like as more and more
current is forced through it, with the result that the transistor
starts looking more and more like a single piece of low-resistance "P"
type material as more and more current flows through the
base-to-emitter junction. That being the case, collector current will
flow when base current does, and will increase with increasing base
current until the transistor goes into saturation. Of course it's the
base-to-emitter voltage which makes the whole thing happen, but what
_I_ think is misleading is to burden an inquirer with too much detail
too soon. Hence, initially describing the BJT in terms of beta and
leaving out the transconductance part alleviates the confusion which
will inevitably arise if the BJT and the FET are both described in
terms of transconductance. After all, the question wasn't "How are
the BJT and the FET alike?" it was "How are they different?".
---

In a MOSFET, however, the only movement of charge required to control
the drain-source current is that required to charge and discharge the
gate capacitance.

Correct. The time it takes to perform this charge/discharge cycle
dictates the maximum useable frequency of the FET.

---
Why even bring that up? it's not germane to the discussion and it's
not true. Usable output may be obtained, depending on the
application, if the gate capacitance is only partially charged and
discharged.

--
John Fields

 

[John Fields]

On Sun, 09 Jan 2005 14:31:59 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On Sun, 09 Jan 2005 01:31:39 -0600, John Fields
jfields@austininstruments.com> wrote:

and a fet will do
a simmilar thing only doesn't require a current ? (at whichever terminal
corresponds to a base on a bipolar)

---
Yes, but it still requires current to charge the gate capacitance.
However, once that capacitor is charged up, current can flow through
the drain-to-source channel with no further current required into the
gate.

Now the OP will be confused by another over-simplification. It depends
on whether the FET is of the enhancement or depletion mode type. Your
statement is correct for enhancement mode FETs, but wrong for
depletion mode ones. Depletion mode FETs are 'normally on' and will
conduct fully with *no* applied gate voltage. You have to apply a
*negative* voltage to the gate to moderate the drain current. Enough
negative voltage will cut-off the drain current altogether. No doubt
*you* know this, but it should be pointed out to the OP.

---
Have you paid any attention at all to the subject line? It reads:

"difference between bipolar and mosfet", not "How many different
flavors of FETs are there?"

As far as confusion goes, I'm sure that your refusal to KISS have done
little to alleviate the OP's.


--
John Fields

 

[Kevin Aylward]

John Fields wrote:

On Sun, 09 Jan 2005 14:31:59 GMT, Miles Harris <mazzer@yahoo.com
wrote:

On Sat, 08 Jan 2005 11:11:22 -0600, John Fields
jfields@austininstruments.com> wrote:

The application of a forward voltage to the base-emitter junction
of a bipolar transistor will, of course, cause charge to flow
between the collector and emitter, but the movement of charges
across the base-emitter junction _is_ relevant, since without that
movement there can be no collector current.

Yes, but that's misleading. It's essential to concentrate on the
relationship between the applied voltage to the base/emitter junction
and the resultant collector current. The BJT is a transconductance
device and should be viewed as such.

---
It's only a transconductance device because of the voltage required to
force charge through the base-to-emitter diode,

No. They are a transconductance device because applying a voltage across
the base emitter junction injects carriers from the emitter to the base
*region*. This charge essentially *all* flows out of the collecter, not
the base terminal.

http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/info/comp/active/BiPolar/page2.html

that charge changing
the electrical properties of the base material to more closely
approximate those of the collector and emitter. That is, when charge
is injected into the base-to-emitter diode of a PNP transistor, the
"N" type base material becomes more and more "P" like as more and more
current is forced through it, with the result that the transistor
starts looking more and more like a single piece of low-resistance "P"
type material as more and more current flows through the
base-to-emitter junction.

This is not an accurate description of the bipolar transistor. This
description is more relevant to operation of the mosfet. The npn
junction simply does not act like a slap of N type. If it did, base
current would be huge.

That being the case, collector current will
flow when base current does, and will increase with increasing base
current until the transistor goes into saturation. Of course it's the
base-to-emitter voltage which makes the whole thing happen,

Indeed it is.

but what
_I_ think is misleading is to burden an inquirer with too much detail
too soon.

This is not too much detail at all. Its can't get any simpler. vbe
controls the collector/emitter current. End of story.

Hence, initially describing the BJT in terms of beta and
leaving out the transconductance part alleviates the confusion which
will

No. No. No. It most certainly doesn't.

Referring to the bipolar as "a current controlled device" causes never
ending confusion that is a bloody nightmare to correct. This is a case
in point. You yourself are trying to put forward the idea that that idea
has merit. It doesn't.

inevitably arise if the BJT and the FET are both described in
terms of transconductance.

Since this is the actual truth to the matter, this is what should be
said. Lying doesn't help one iota.

. After all, the question wasn't "How are
the BJT and the FET alike?" it was "How are they different?".

They are different, in part, in that the bipolar requires base current,
but that this base current is simply a nuisance.


Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Kevin Aylward]

Robert Monsen wrote:

Kevin Aylward wrote:
snip arguments for and against

The fact that current through a bipolar transistor and a diode are
described by basically the same equation points to the fact that a
bipolar transistor is really just a diode, in which many or most of
the electrons that would normally escape through the base are
diverted to the collector by the geometry and chemistry of the device
and voltage on the collector. Since a diode is clearly a voltage
controlled device, it is clear that the voltage across the PN
junction of the base to emitter that causes electron flow.

However, saying that current through the base has nothing to do with
this is just wrong.

Not in this context it isnt.

Because of the fact that a diode is involved, the
only way to keep the voltage of the base up is to pull electrons out
of it through the base lead. The ratio of electrons out the base lead
to electrons out the collector is 'fairly' stable, enough to be
printed in datasheets as the famous hfe or beta parameter.

No its not stable. Hfe varies all over the place. In contrast, the gm
equation of a transistor is the same for all transistors.

Any decent design has to be done such that the huge variations in hfe
are overcome.

Because of this, the base current is yet another feature of the
bipolar transistor that can be used to roughly predict the collector
current, and thus to design circuits with.

No it most certainly cant be used to predict the collector current. For
switching circuits it is used to calculate the *minimum* base current
required, with the collector current being set by the collector loop not
the base loop.

For ac circuits, hfe is designed out.

It is also easier to use,
in my opinion, owing to the fact that the relationship between base
and collector current is generally linear, within certain ranges.

Ho hum...you don't do much transistor design do you?

This is a non starter.

On the other hand, in my experience, the voltage to current equation
is far more less use, since Is is not generally published in
datasheets, and is severely temperature dependent to boot (just like
beta).

Oh dear...in your experience...well, yet again, at the risk of sounding
arrogant, my experience is rather more extensive then yours in the
design of complex transistor level circuits. I have been professionally
designing very large transistor count i.c. and board level circuits for
well, some time now.

The gm equation is absolutely indispensable. It forms the heart of
serious transistor level design. For example, see
http://www.anasoft.co.uk/EE/bipolardesign1/bipolardesign1.html

e.g.

re = 1/40Ic

Av = Rc/re

max gain Av=Va/Vt

or the design of current mirrors, multipliers, bandgap voltage
references. The list is truly endless.

Predicting the current through the collector of a a 2N3904,
given a base voltage, is practically impossible.

Sure, if you just apply a raw voltage for DC conditions, but one doesn't
usually do this. For ac conditions, ic= vb.40.Ibias

Predicting the
current through a 2N3904 using beta is simple, if somewhat imprecise.
By guessing a beta of 100, one can easily see that 10uA through the
base will give about 1mA through the collector.

Oh dear, this approach is useless for anything but switching circuits,
and as noted above, it doesn't determine the collector current. This is
shown here
http://www.anasoft.co.uk/EE/bipolardesign3/bipolardesign3.html

Both beta and EM have their place in one's toolkit. Why toss out tools
that can be useful?

No one is claiming that beta has no use, one is pointing out that the
bipolar transistor is a voltage controlled device.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[John Fields]

On Sat, 15 Jan 2005 13:57:51 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On Fri, 14 Jan 2005 10:58:06 -0600, John Fields
jfields@austininstruments.com> wrote:

[semantics snipped]

Consequently, it's not a question of lack of comprehension on my part,
but a lack of clarity on yours.

More semantics.. Where's the beef??

However, I should have guessed that would be your method of choice
judging from the bob-and-weave tactics you've employed in your earlier
posts.

Semantics again...

[snip more bilge]

Well, IME, for the same If, Vf depends on what the diode's made of.

No really??? Goodness me!

---
Now that I've explained it to you you can pretend you knew it all
along?

Here's a little something (Positively Fourth Street) from Bob Dylan
you might identify with: (Pay particular attention to the sixth,
eleventh, and twelfth verses.)


You got a lotta nerve
To say you are my friend
When I was down
You just stood there grinning

You got a lotta nerve
To say you got a helping hand to lend
You just want to be on
The side that's winning

You say I let you down
You know it's not like that
If you're so hurt
Why then don't you show it

You say you lost your faith
But that's not where it's at
You had no faith to lose
And you know it

I know the reason
That you talk behind my back
I used to be among the crowd
You're in with

Do you take me for such a fool
To think I'd make contact
With the one who tries to hide
What he don't know to begin with

You see me on the street
You always act surprised
You say, "How are you?" "Good luck"
But you don't mean it

When you know as well as me
You'd rather see me paralyzed
Why don't you just come out once
And scream it

No, I do not feel that good
When I see the heartbreaks you embrace
If I was a master thief
Perhaps I'd rob them

And now I know you're dissatisfied
With your position and your place
Don't you understand
It's not my problem

I wish that for just one time
You could stand inside my shoes
And just for that one moment
I could be you

Yes, I wish that for just one time
You could stand inside my shoes
You'd know what a drag it is
To see you

Bob Dylan
---

Easy enough to check it out... get yourself a 9V battery, a 20K
rheostat, a silicon junction diode, a Schottky diode, a 0-1mA ammeter
and a 0-1V voltmeter. Making sure you have the rheostat cranked to
the max resistance position, connect everything up like this:


+9V
|
[R]
|
+----->>----+
|A |
[DUT] [0->1V]
| |
+----->>----+
|
[0->1mA]
|
-9V

Then, adjust the rheostat to the position required to make the
milliammeter read 1mA, note whether the DUT is the Schottky or not and
write that down along with the voltage indicated by the voltmeter when
the milliammeter reads 1mA. Do the same thing using the remaining
diode and report back to us with what you find, OK?

I don't have to do this stupid experiment. Any half-competent engineer
will know that the barrier height potential of the Schottky will be
*much* lower than a 'comparable' silicon diode.

---
And yet, "knowing" all that you chose to make this unqualified
statement earlier on?:

"You *do* realize that one diode drop at room temperature is only just
over half a volt, don't you, Junior?"

I'd say that sentence speaks volumes about your competence.
---

You're talking maybe
270mV. Germaniums likewise (but you won't remember germanium diodes,
Junior).

---
Sure I do. they were after copper oxide and selenium, but before
silicon.
---

Shall we perform your dumb experiment with other types, too?

---
An experiment can't be dumb, [stupid] but the experimenter can.
That's why I suggested that _you_ start with the pot cranked to
maximum resistance.
---

How about a back diode? can you get any lower than that?

---
I'd have to look it up to find out, but the subject isn't diodes with
a negative resistance characteristic, it's just plain ol' garden
variety rectifiers.
---

Before you can determine whether or not someone knows how a BJT works,
you need to know how a diode works. You haven't demonstrated any real
competence in that arena, so I suggest you do the experiment I
described and see what you can learn from it.

If I learned anything new from *that* experiment I'd give up
electronics altogether tomorrow.

---
Hmmm... Where have I heard _this_ before?:

"You *do* realize that one diode drop at room temperature is only just
over half a volt, don't you, Junior? "
---

Before you start making noises about who knows what about BJTs you
really ought to get that diode theory down.

There's nothing wrong with my diode theory, Junior. I'd probably
completed my studies before you were even born. Don't talk back to
your elders and betters. Learn some respect.

---
Fuck you. Respect is earned. I'll do what pleases _me_, not walk on
eggshells the way you'd like me to in order to make your life more
convenient for you.
---

---

Plus I'll wager from your postings that you're a good
few years older than he is.

---
So, the obvious you don't have much trouble with?

Sorry, no compliment intended. I infer you're older in view of your
cockiness and the foul language you readily resort to each time your
ignorance is exposed.
HAND, Junior!

---
Ignorance isn't exposed by the use of "foul" language, it's exposed by
posting material full of errors as you are wont to doing.

Also, PKB with that "FOAD" to Jim Thompson in abse, no?

--
John Fields

 

[Miles Harris]

On Sat, 15 Jan 2005 11:39:31 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Sat, 15 Jan 2005 16:46:52 GMT, Miles Harris <mazzer@yahoo.com
wrote:

On Sat, 15 Jan 2005 09:47:38 -0600, John Fields
jfields@austininstruments.com> wrote:

Now that I've explained it to you you can pretend you knew it all
along?

I ain't pretendin' nuthin'. This is all *basic* stuff and nowhere near
even undergrad level.

Here's a little something (Positively Fourth Street) from Bob Dylan
you might identify with: (Pay particular attention to the sixth,
eleventh, and twelfth verses.)

6:
Do you take me for such a fool
To think I'd make contact
With the one who tries to hide
What he don't know to begin with
11:
I wish that for just one time
You could stand inside my shoes
And just for that one moment
I could be you
12:
Yes, I wish that for just one time
You could stand inside my shoes
You'd know what a drag it is

[bafflement]

---
What a surprise!
---

None of which is applicable here. Thank God they don't write 'em like
that anymore.

---
Don't undestand allusion, huh?

I understand allusion perfectly, Junior. What I don't understand is
why some spotty-faced, high-school-reject jerkoff like you would want
to post lyrics from a song that so clearly flags up his own
self-loathing. You're so full of yourself in your postings, yet you
cite self-disparaging lyrics that basically show you up to be the sad,
sorry-assed, sack of s**t loser/loner that you really are. That's
quite an admission in a world-wide public forum!

A 9V lead-acid battery? Where would you propose to find one of those?

I appreciate you're only trolling here, Junior, but if you do a little
research on the Web you'll find that such batteries are comprised of a
series of lower value cells. You just place them in series and stick
'em in one box and voila: you have the required voltage.
BTW, I don't appreciate sarchasm from spotty-faced, high school
rejects, so cut the crap and show some respect, boner.

Nonsense? Schottkys _are_ as plain ol' garden variety diodes as
silicon junction diodes are WRT negative resistance characteristics,
but that's hardly the point, the point being that you made the
statement (no matter how you hard you try to slime out of it) that a
diode's Vf is about 0.5V at room temp, which it is _not_ if you're
talking about a silicon junction diode, which we were.

You can't have it both ways, Junior. Let me repost that quote of mine
that you're so fond of citing in this thread:

"You *do* realize that one diode drop at room temperature is only just
over half a volt, don't you, Junior? "

Now, please tell us which common-or-garden, run-of-the-mill,
general-purpose silicon diode *doesn't* have a drop of "just over half
a volt" at room temperature??

Your ignorance is only exceeded by your persistence, I'll grant you
that.

---
Then you acknowledge that my persistence is > 0. Thank you!

Yes, I do. As is clear for all to see. Sadly, I don't have Kevin
Aylward's degree of persistence, however.
I find it exceedingly tiresome to have to repeat, ad nauseam, the kind
of entry-level basics that my youngest son was acquainted with a good
3 years ago.

Did you really think the lyrics I posted earlier were from a rap song?

Certainly not. I know the song you quoted, but like everything else
Dylon wrote, it's an overvalued crock of s**t. I'd wager that in truth
you get off on the likes of Eminem, 50 Cent, Tupac and Dr. Dre. That's
where you get your dire attitude problem from, IMO.

I blame phony, self-important bastards like you who drive them to want
to do _anything_ but be like you. Watch that eleven-year-old...

Why wouldn't anyone want to be successful and erudite? Why wouldn't
anyone want to be able to piss all over jerks like you in debates? Why
wouldn't anyone want to be able to see through the smoke and cut to
the quick?
My youngest (like his siblings) is going to grow up to be just like
his dear old dad - a chip off the old block - whether he likes it or
not. It's for the best. The alternative is too horrific to
contemplate. It's just a tragedy that I can't save him from exposure
to the poisonous, soul-destroying influences of the rap music culture
that you so clearly embrase and embody.

IKYABWAI? Pretty lame, Bozo!

I'm not familiar with that term and I shudder to think what it might
mean, coming from a foul-mouthed young hudlum like you. Kindly
preserve my igorance!

Also, PKB with that "FOAD" to Jim Thompson in abse, no?

"FOAD" isn't a swear word; it's an acronym containing one. I wouldn't
stoop so low as post the 'F-word' in a public forum.

---
But you'd stoop even lower by refusing to?

No, I'm simply maintaining my place on the moral high ground.

An interesting picture of you is emerging from this exchange;
basically that of someone who is afraid to say what he really means or
with being associated with having said it. Basically, a coward.

We don't all live in a free country, Junior. My right to say what I
believe has been proscribed by the stinking British government. Just
think yourself lucky that you're alive and well in a country that's
only too happy for you to sit in front of your dumb TV shows, jerking
off at all those topless models.

And from what I've read of Mr. Thompson's contributions, he makes pretty frequent
use of the acronym himself.

---
Sure, but he uses it for the sake of brevity, not for the sake of the
false propriety you swim in.

There's nothing false about me, Junior.

As we say in Texas,

"Tu eres un come mierda."

Does your mommy know you have access to a computer??

 

[Bob Myers]

"Miles Harris" <mazzer@yahoo.com> wrote in message
news:3ngou01jd7s82eks14ghhvta2hs386a5ak@4ax.com...

NOTHING!!!
Come on, you gutless bonehead! Respond and defend your position!

May I ask - are you under the impression that this is some
sort of competition, and that you will be awarded some sort
of prize if you "win"?

If not, then what is the motivation for the above?


Bob M.

 

[John Fields]

On Mon, 17 Jan 2005 23:02:03 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On Sun, 16 Jan 2005 16:47:48 GMT, Miles Harris <mazzer@yahoo.com
wrote:

On Sat, 15 Jan 2005 11:39:31 -0600, John Fields
jfields@austininstruments.com> wrote:

NOTHING!!!
Come on, you gutless bonehead! Respond and defend your position!

---
Down, boy!
You don't get to go out and play much, do you?

You're used to a leash, so you ought to know it'll be _If_ I choose,
and _when_ I choose.

--
John Fields

 

[Miles Harris]

On Mon, 17 Jan 2005 20:07:59 -0600, John Fields
<jfields@austininstruments.com> wrote:

With a terminal voltage of about 2.041V,

http://www.tpub.com/content/doe/hdbk1084/css/hdbk1084_24.htm

There's no way you can get 9V out of any number of lead-acid cells no
matter how you choose to arrange them or what kind of a box you put
them in, LOL! Now, you can't get much more basic than batteries, and
you obviously don't know what you're talking about even there, so
you're running at about what so far? Zero for two?

So you're saying I can't get 9V from a lead-acid battery?? And I'm not
talking about relying on any type of rheostat or voltage-dropper here.
You're saying it's impossible for me to get 9V out of a lead-acid
battery by itself alone? Are you serious?

Now, please tell us which common-or-garden, run-of-the-mill,
general-purpose silicon diode *doesn't* have a drop of "just over half
a volt" at room temperature??

Rather than just handing you the information, I think it would be a
good thing if you got off of your fat, lazy, ass and performed that
little experiment I suggested and then post what you find. I mean,
after that battery fiasco aren't you even interested in finding out
whether what you think you know about diodes is true?

IOW: "Holy crap! Miles has boxed me into a corner here so rather than
admit to the fact that I was wrong all along I'll try another
diversionary tactic."
Look, Junior, your 'experiment' simply demonstrates that the barrier
height potential of the Schottky is around half the level of a regular
silicon diode. You OTOH seem to think they're the same thing and
therefore interchangeable, presumably. I wonder why they bother to
make Schottkys then? <sigh...>

As usual, you're wrong on all counts and the attitude only _seems_
dire to pukes like you because you're used to people falling for your
crap and not contesting it.

I'm certainly not used to having my opinions questioned by a
snotty-faced school kid, that's for sure. You gotta lot of nerve,
Junior. Most good folks simply accept what I tell them and go away
wiser for it. Not so in your case, however. :-(

If the price of achieving those goals is winding up with a personality
like yours, I can see why a lot of folks would rather be failures.

You don't like my personality? Sounds like sour grapes on your part,
Junior.

They can try if they want to, but I'll just piss back harder.

I haven't seen any evidence of that yet...

You're an idiot. You have no idea who I am or what I believe in, and
yet you consider yourself fit to make pronouncements based upon your
opinions, pretty much the same way you've fallen on your face
pretending you have technical skills.

I've made a good living from my technical skills over the years,
Junior. People don't pay you good money for being a bonehead. Now,
isn't it about time you stopped jerking off in front of that computer
and went back to high school?

No, I'm simply maintaining my place on the moral high ground.

Crappola. All you're doing is posturing, pretending that you're
"above it all".

Certainly not. it's beneath my dignity.

Yeah, ours was too until we kicked the British government out of here.

Shame you can't kick them out of *here* as well!

There's a lot better porn on the net than there is on TV, I'm sure you
know, and it's not luck that we are where we are. First we had to
kick out the Brits and lose a lot of lives doing that, then we had to
jump into WW1 to _save_ the Brits and then, a few years later jump
into WW2 to save the Brits again. We _all_ lost a lot of lives to
"save the world", and a little luck here and there helped, but it
wasn't _all_ serendipetous.

Britain wasn't occupied in either WW so I don't know where you got
that lofty idea from. And 'you' were quite happy to sit on the
sidelines and twiddle your thumbs until the Nips blew Pearl Harbor all
to hell. If that incident hadn't forced your hand after more than 2
years of inaction, you'd probably have stayed out of WW2 altogether
and left us to get on with it alone.

Does your mommy know you have access to a computer??

---
She may not, since she's dead, but _you_ sure as hell do!

Correct. To my very great intellectual cost!
I wonder if entering into discourse with the ignorami can eventually
result in organic brain damage? :-/
Time will tell.

 

[John Fields]

On Tue, 18 Jan 2005 14:41:25 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On Mon, 17 Jan 2005 20:07:59 -0600, John Fields
jfields@austininstruments.com> wrote:

With a terminal voltage of about 2.041V,

http://www.tpub.com/content/doe/hdbk1084/css/hdbk1084_24.htm

There's no way you can get 9V out of any number of lead-acid cells no
matter how you choose to arrange them or what kind of a box you put
them in, LOL! Now, you can't get much more basic than batteries, and
you obviously don't know what you're talking about even there, so
you're running at about what so far? Zero for two?

So you're saying I can't get 9V from a lead-acid battery?? And I'm not
talking about relying on any type of rheostat or voltage-dropper here.
You're saying it's impossible for me to get 9V out of a lead-acid
battery by itself alone? Are you serious?

---
Yeah, but I'm not talking about cheating and loading the battery down
so hard that its internal resistance drops 3V (if it's a 12V battery).

But, I could be wrong, so what did you have in mind?
---

Now, please tell us which common-or-garden, run-of-the-mill,
general-purpose silicon diode *doesn't* have a drop of "just over half
a volt" at room temperature??

Rather than just handing you the information, I think it would be a
good thing if you got off of your fat, lazy, ass and performed that
little experiment I suggested and then post what you find. I mean,
after that battery fiasco aren't you even interested in finding out
whether what you think you know about diodes is true?

IOW: "Holy crap! Miles has boxed me into a corner here so rather than
admit to the fact that I was wrong all along I'll try another
diversionary tactic."
Look, Junior, your 'experiment' simply demonstrates that the barrier
height potential of the Schottky is around half the level of a regular
silicon diode. You OTOH seem to think they're the same thing and
therefore interchangeable, presumably. I wonder why they bother to
make Schottkys then? <sigh...

---
The purpose of the experiment is to prove that your statement that the
Vf of a silicon junction ("regular")diode is a little over 0.5V is
wrong. The reason for performing the experiment on a Schottky diode
as well is to show that the Vf of a Schottky is lower than that of a
silicon junction diode. So do the experiment and prove that I'm wrong
and that the Vf of a silicon junction diode _is_ close to 0.5V, or
shut up.
---

As usual, you're wrong on all counts and the attitude only _seems_
dire to pukes like you because you're used to people falling for your
crap and not contesting it.

I'm certainly not used to having my opinions questioned by a
snotty-faced school kid, that's for sure. You gotta lot of nerve,
Junior. Most good folks simply accept what I tell them and go away
wiser for it. Not so in your case, however. :-(

---
Well, yes. I tend to be critical of blowhard self-proclaimed
purveyors of "Trooth", who do little more than proselytize.
---

If the price of achieving those goals is winding up with a personality
like yours, I can see why a lot of folks would rather be failures.

You don't like my personality? Sounds like sour grapes on your part,
Junior.

---
It's not that _I_ like it or dislike it, I do neither. I look on it
as just another manifestation of an ego trying desperately to seem
important.
---

They can try if they want to, but I'll just piss back harder.

I haven't seen any evidence of that yet...

---
Selective vision at work...
---

You're an idiot. You have no idea who I am or what I believe in, and
yet you consider yourself fit to make pronouncements based upon your
opinions, pretty much the same way you've fallen on your face
pretending you have technical skills.

I've made a good living from my technical skills over the years,
Junior.

---
Well, you may have made a good living, but if you have to ask for help
with writing a verbal description of the internal resistance of a
battery, then I suggest that the quality of your "technical skills"
is suspect.
---

People don't pay you good money for being a bonehead.

---
If they're bigger boneheads than you are and you can talk them into it
they will.
---

Now, isn't it about time you stopped jerking off in front of that computer
and went back to high school?

---
Actually, you're right. This exchange seems to be little more than
mental masturbation, and I _do_ need to get some development work
done, so I think after this post I'll just cut you loose and leave
you to your own devices.
---

No, I'm simply maintaining my place on the moral high ground.

Crappola. All you're doing is posturing, pretending that you're
"above it all".

Certainly not. it's beneath my dignity.

---
OK, then, one more thing you _can't_ do.
---

Yeah, ours was too until we kicked the British government out of here.

Shame you can't kick them out of *here* as well!

---
Count me out of that one. We've got enough problems over here without
taking on yours as well. You fix it.
---

There's a lot better porn on the net than there is on TV, I'm sure you
know, and it's not luck that we are where we are. First we had to
kick out the Brits and lose a lot of lives doing that, then we had to
jump into WW1 to _save_ the Brits and then, a few years later jump
into WW2 to save the Brits again. We _all_ lost a lot of lives to
"save the world", and a little luck here and there helped, but it
wasn't _all_ serendipetous.

Britain wasn't occupied in either WW so I don't know where you got
that lofty idea from.

---
Had we not jumped in the first time you would have been, and there
probably would not have been a Britain to defend the second time.
---

And 'you' were quite happy to sit on the
sidelines and twiddle your thumbs until the Nips blew Pearl Harbor all
to hell. If that incident hadn't forced your hand after more than 2
years of inaction, you'd probably have stayed out of WW2 altogether
and left us to get on with it alone.

---
Well, we preferred to _try_ to remain neutral, but no... somebody
always has to start shit and then we get involved in it because we get
asked to or because we get war declared on us and then everything just
spirals out of control and it turns into a big ol' war.

As far as the Japs are concerned, they attacked us on December 7th of
1941, and we probably would have gone off and just taken care of that
if it hadn't been for Germany declaring war on us a few days later, so
maybe it's lucky for you all that in addition to being attacked by the
Japs, the Germans also declared war on us. We eventually would have
jumped in to help you guys, we always do, but the German action left
us little choice about the timeline. Anyway, that's all water under
the bridge, and what we're _really_ talking about is your technical
incompetence.
---

Does your mommy know you have access to a computer??

---
She may not, since she's dead, but _you_ sure as hell do!

Correct. To my very great intellectual cost!

---
Uh-huh... Kind of like you showing me that you've squirrelled away a
lot of currency into a safe deposit box and then me explaining to you
why it's all counterfeit.
---

I wonder if entering into discourse with the ignorami can eventually
result in organic brain damage? :-/

---
As opposed to what? Inorganic brain damage?

--
John Fields

 

[Miles Harris]

On Thu, 13 Jan 2005 17:55:54 -0600, John Fields
<jfields@austininstruments.com> wrote:

Nothing of the kind. Kevin and I have been at loggerheads with each
other more than once in the past, and he knows that I have a great
deal of respect and affection for him, so your disingenuous
"refereeing" falls on deaf ears. However, _your_ sickening pomposity
has been noted.

I can only apologize.
Sadly, It's all too easy to fall into the trap of talking down to
one's inferiors. Especially when the ability-gulf is so wide.
I don't wish to appear patronizing, but in your case, it's
unavoidable.
HAND.

 

[John Fields]

On Thu, 13 Jan 2005 08:34:10 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Thu, 13 Jan 2005 10:38:26 GMT, Miles Harris <mazzer@yahoo.com
wrote:

On Wed, 12 Jan 2005 11:58:08 -0600, John Fields
jfields@austininstruments.com> wrote:

Beta is simply collector current divided by base current. At the OP's
current <G> level of understanding, that's all he needs to know, so
why would it take you longer than a minute to come up with that?

You've pre-empted my considered view on the matter (see my posting of
earlier today further up the thread).

---
I should go on a wild goose chase at your insistence? Forget it. If
you have something to say, include it in the current post.

---
That was unnecessarily nasty. I apologize.

--
John Fields

 

[John Fields]

On Thu, 13 Jan 2005 22:41:00 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On Thu, 13 Jan 2005 08:14:21 -0600, John Fields
jfields@austininstruments.com> wrote:

Actually, it's "What's the point of whipping a dead horse?" (Not you,
Kevin, the subject material.

Well it appears that Kevin has straightened out your misconceptions
about how a transistor works and set you on the right road to further
studies on a firm foundation. I suppose it's too much to expect you to
show him an ounce of gratitude for his (considerable) time and
trouble. :-(

---
Nothing of the kind. Kevin and I have been at loggerheads with each
other more than once in the past, and he knows that I have a great
deal of respect and affection for him, so your disingenuous
"refereeing" falls on deaf ears. However, _your_ sickening pomposity
has been noted.

--
John Fields

 

[Miles Harris]

On Fri, 21 Jan 2005 00:20:01 GMT, "Anthony Fremont"
<spam@anywhere.com> wrote:

I disagree. Even a fully discharged lead-acid battery at just above
freezing still has an unloaded voltage of almost 2V/cell. 5 cells are
going to be 9.8V minimum. I think "Junior" is correct. ;-)

Well that's not my experience, so shove off.

 

[Robert Monsen]

Skeleton Man wrote:

Just wondering could someone explain fairly simply what the difference is
between a bipolar and a fet ? Can I put a bipolar in place of a fet or vice
versa ?

Regards,
Chris

The most basic difference is that a bipolar transistor requires current
at the control terminal (the base lead), whereas a mosfet requires none.
However, there are advantages to both in different situations.

You generally cannot substitute a bipolar transistor for a fet, because
the circuit will not be designed to supply the required base current.

MOSFETs have three leads, a source, a gate, and a drain. Bipolar
transistors also have three leads, but they are called emitter, base,
and collector. These leads roughly correspond to one another, ie, the
emitter is like the source, the base is like the gate, and the collector
is like the drain. Making the base (gate) more positive (for NPN and
N-MOSFETs) or negative (for PNP or P-MOSFETs) with respect to the
emitter (source) causes more current to flow from collector (drain) to
emitter (source).

This terminology is totally confusing, and, sadly, you just have to get
used to it if you want to talk about these things.

MOSFETs are used to construct CMOS devices, and are thus the main
transistor component to microprocessors. They are also good for
constructing huge power transistors, which are easier to control due to
the lack of required gate current.

Bipolar transistors are generally more useful for analog design, where
the lower noise, more easily predicted voltage requirements, and lower
control voltages are useful.

For a FET, the electrostatic field of charges on the control terminal
(the gate) is used to moderate the output. MOSFETs have a silicon oxide
layer that insulates the gate from the charge. JFETs use a
reverse-biased PN junction's depletion region to isolate the gate from
the source and drain. For bipolar transistors, the movement of charges
across PN junctions controls the output.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.