What characterizes a powerFET for audio use?

[N_Cook]

Other than p channel in this case , same for BUZ901P nch
eg BUZ906P 200V, 8A ,datasheet says
"POWER MOSFETS FOR
AUDIO APPLICATIONS"
but also
"FEATURES ... (for use in)
HIGH SPEED SWITCHING ... "

Would a powerFET designed solely for high speed switching use and 125W
rating be derated in power handling terms to only 50W say for linear 10
Hz use. Or secondary oscillation liability if paralleled up devices? or
some other operational failing in audio use not found with smps say ?

[Phil Allison]

"Nutcase Kook" is a pig ignorant pommy cunt


> Other than p channel in this case, same for BUZ901P nch

> eg BUZ906P 200V, 8A ,datasheet says
> "POWER MOSFETS FOR
> AUDIO APPLICATIONS"
> but also
> "FEATURES ... (for use in)
> HIGH SPEED SWITCHING ... "

** The Semelab app note makes it pretty clear there is a HUGE difference
between "switching" and audio ( ie lateral) power mosfets.

http://products.semelab-tt.com/pdf/ApplicationNoteAlfet.pdf

> Would a powerFET designed solely for high speed switching use and 125W
> rating be derated in power handling terms to only 50W say for linear 10 Hz
> use. Or secondary oscillation liability if paralleled up devices? or some
> other operational failing in audio use not found with smps say ?

** Yawnnnnnnnnnnnnnnn....

More brainless, fucking TROLLING !!!!!!!

FOAD you vile pommy cunthead.



.... Phil

[dave]

"Figure of Merit" in pulsed applications vs "efficiency" in linear
applications. RMS Power is measured in heating ability v DC.

[William Sommerwerck]

"dave" wrote in message
news:Mpmdnce3Qvd7g1nP...@earthlink.com...

> "Figure of Merit" in pulsed applications vs "efficiency"
> in linear applications.

Any (???) device can produce more peak power in pulsed mode than continuous,
because it spends less time in the region where it dissipates the most power.


> RMS power is measured in heating ability versus DC.

There is no such thing (other than in a mathematical sense) as RMS power.
Voltage and current can have RMS (root-mean-square) values. Squaring voltage
and dividing by resistance, or squaring current and multiplying by resistance
produces the //average// power.

[dave]

http://www.learningaboutelectronics.com/Articles/RMS-voltage-and-current-explained.php

The audio duty cycle makes the device heat up more than pulsating full
on/full off does. That's the spec and the spec is based on a temperature
that will destroy the gate, source, drain, diode, etc. In audio service
an FET is always drawing some current, due to the high turn-on
threshold. The bias is just slightly above cutoff. Many amps use this
quiescent current to set the bias, either measured directly or by
measuring current draw at the mains.

[dave]

On 01/01/2014 06:28 AM, William Sommerwerck wrote:

And FOM is used (by me) because the efficiency is above 100%.

[Maynard A. Philbrook Jr.]

In article <yoGdnWbbYokO7lnP...@earthlink.com>,
rick...@earthlink.net says...

Oh really? have you found some over unity energy somewhere?

Jamie

[Jeff Liebermann]

RMS power is quite real. A true-RMS voltmeter uses a pair of heating
elements and thermocouples to produce a measurement because it's the
best way to measure the equivalent voltage that would generate the
same amount of heat. There are versions that use other methods but
the thermocouple is generally the closest to the real heating value.




--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[William Sommerwerck]

"Jeff Liebermann" wrote in message
news:67v8c91klphqp0mpa...@4ax.com...

> RMS power is quite real. A true-RMS voltmeter uses a pair of heating
> elements and thermocouples to produce a measurement because it's
> the best way to measure the equivalent voltage that would generate
> the same amount of heat. There are versions that use other methods
> but the thermocouple is generally the closest to the real heating value.

The heating value of a waveform is the average value of its power, NOT the RMS
value of its power.

Many years ago I sat down and calculated this for a sine wave. I assure you, a
sine wave's average power and its RMS power are not at all the same. RMS
applies ONLY to voltage and current.

[Phil Allison]

"dave the dickhead "

>> "Nutcase Kook" is a pig ignorant pommy cunt
>>
>>
>>> Other than p channel in this case, same for BUZ901P nch
>>> eg BUZ906P 200V, 8A ,datasheet says
>>> "POWER MOSFETS FOR
>>> AUDIO APPLICATIONS"
>>> but also
>>> "FEATURES ... (for use in)
>>> HIGH SPEED SWITCHING ... "
>>
>>
>> ** The Semelab app note makes it pretty clear there is a HUGE difference
>> between "switching" and audio ( ie lateral) power mosfets.
>>
>> http://products.semelab-tt.com/pdf/ApplicationNoteAlfet.pdf
>>
>>
>>> Would a powerFET designed solely for high speed switching use and 125W
>>> rating be derated in power handling terms to only 50W say for linear 10
>>> Hz
>>> use. Or secondary oscillation liability if paralleled up devices? or
>>> some
>>> other operational failing in audio use not found with smps say ?

>

> "Figure of Merit" in pulsed applications vs "efficiency" in linear
> applications. RMS Power is measured in heating ability v DC.

** Yaaawnnnnnnn - more stupid fucking bullshit !!!!!!!!!!!!!!

One colossal fool asks an idiotic question and even BIGGER fools reply.



.... Phil

[Maynard A. Philbrook Jr.]

In article <67v8c91klphqp0mpa...@4ax.com>,
je...@cruzio.com says...

>
> On Wed, 1 Jan 2014 06:28:29 -0800, "William Sommerwerck"
> <grizzle...@comcast.net> wrote:
>
> >"dave" wrote in message
> >news:Mpmdnce3Qvd7g1nP...@earthlink.com...
> >
> >> "Figure of Merit" in pulsed applications vs "efficiency"
> >> in linear applications.
> >
> >Any (???) device can produce more peak power in pulsed mode than continuous,
> >because it spends less time in the region where it dissipates the most power.
> >
> >
> >> RMS power is measured in heating ability versus DC.
> >
> >There is no such thing (other than in a mathematical sense) as RMS power.
> >Voltage and current can have RMS (root-mean-square) values. Squaring voltage
> >and dividing by resistance, or squaring current and multiplying by resistance
> >produces the //average// power.
>
> RMS power is quite real. A true-RMS voltmeter uses a pair of heating
> elements and thermocouples to produce a measurement because it's the
> best way to measure the equivalent voltage that would generate the
> same amount of heat. There are versions that use other methods but
> the thermocouple is generally the closest to the real heating value.

I got into his long ago, and all the proclaimed experts came out of the
wood work to say I was wrong. RMS power ratings have been stuck on
equipment as long as I can remember.

Jamie

[Phil Allison]

"William Sommerwerck"

>
> Many years ago I sat down and calculated this for a sine wave. I assure
> you, a sine wave's average power and its RMS power are not at all the
> same. RMS applies ONLY to voltage and current.

** But even a complete fool like Somerwanker should know that the term "RMS
power" is not meant literally.

It is NOT the RMS value of the instantaneous power level.

In the world of audio, it normally refers to a power measurement done using
the RMS value of a sine wave (or other wave if specified ) voltage delivered
into a known resistive load.

A simple bit of calculus shows that the RMS value of a sine wave to be half
the square root of two ( 0.7071) times its peak value.


.... Phil

[William Sommerwerck]

>> Many years ago I sat down and calculated this for a sine wave. I assure
>> you, a sine wave's average power and its RMS power are not at all the same.
>> RMS applies ONLY to voltage and current.

> ** But even a complete fool...

I can't be a complete fool, because on rare occasions you agree with me.

> ...like Sommerwerck should know that the term "RMS power" is not
> meant literally.

He knows nothing of the sort. Just because people say "pressure" when they
mean "force", doesn't mean pressure and force are the same thing.

I see ads proclaiming that an amplifier delivers "125 watts RMS power". No, it
doesn't. There is a perfectly good term for that... "continuous average
power", or perhaps "continuous average sinewave power". This term has a
specific meaning, and it IS NOT the same as RMS power.

[Jeff Liebermann]

Ok, I yield to a higher authority. Heating power is average power:
<http://www.eznec.com/Amateur/RMS_Power.pdf>
However that doesn't stop nearly everyone from specifying RMS power.

So, why do people buy true-RMS voltmeters? If they don't measure
anything useful, why bother?


[Personal drivel: I haven't forgotten about the HP4 parts. I've been
busy. Today was the lost battle of the clutch master cylinder.
Tomorrow will be the forgotten backdated billing for last year.]

[Phil Allison]

"William Sommerwanker = IDIOT"

>>> Many years ago I sat down and calculated this for a sine wave. I assure
>>> you, a sine wave's average power and its RMS power are not at all the
>>> same. RMS applies ONLY to voltage and current.
>
>> ** But even a complete fool...
>
> I can't be a complete fool,

** Yes you are and about to prove it yet again.

>> ...like Sommerwerck should know that the term "RMS power" is not
>> meant literally.
>
> He knows nothing of the sort.

** Proof given

> I see ads proclaiming that an amplifier delivers "125 watts RMS power".
> No, it doesn't.

** " ... the term "RMS power" is not meant literally."

Cos it is not what the writer meant PLUS there is simply no such quantity
if you do.

FUCKWIT !!!!!!!!!!!!


.... Phil

[Phil Allison]

"Jeff Liebermann"

> Ok, I yield to a higher authority. Heating power is average power:
> <http://www.eznec.com/Amateur/RMS_Power.pdf>
> However that doesn't stop nearly everyone from specifying RMS power.
>

** There is no such quantity as " RMS power " if you are so stupid as to
interpret the term literally.

> So, why do people buy true-RMS voltmeters?

** To get " true RMS " volts of course.

> If they don't measure anything useful,

** The RMS value of a voltage or current could hardly be more useful.

My god, you are SOOOOOO illiterate and SOOOOO retarded.




... Phil

[Jeff Liebermann]

On Thu, 2 Jan 2014 12:22:44 +1100, "Phil Allison" <phi...@tpg.com.au>
wrote:

>"Jeff Liebermann"
>
>> Ok, I yield to a higher authority. Heating power is average power:
>> <http://www.eznec.com/Amateur/RMS_Power.pdf>
>> However that doesn't stop nearly everyone from specifying RMS power.

> ** There is no such quantity as " RMS power " if you are so stupid as to
>interpret the term literally.

Which term should be interpreted non-literally? "RMS" or "power"?

Assuming a stable resistance load (i.e. no light bulbs), the RMS power
is simply the square of the RMS voltage divided by the resistance.
Seem literal enough for me.

>> So, why do people buy true-RMS voltmeters?
>
>** To get " true RMS " volts of course.

Very good. But since there doesn't seem to be any correlation with
heating power (despite using a thermocouple to do the measuring) and
RMS volts or watts, what does the meter indication on a true RMS
voltmeter actually mean? Or is it just a mathematical abstraction?

>> If they don't measure anything useful,
>
>** The RMS value of a voltage or current could hardly be more useful.

Useful for what? Obviously not heating value. Anything I missed?

> My god, you are SOOOOOO illiterate and SOOOOO retarded.

Very perceptive and partly true. I don't take you literally but the
timing on my car is not retarded.

<http://www.aqdi.com/rms.htm>
"You have read that there is no such thing as "RMS power."
Technically, you are right. However, over the years the term,
regarding audio gear, has come to be applied to the measurement
technique outlined above, so we use that language here, rather
than terminology with which the customer is unfamiliar. Yes,
the computation is mathematically an integral of the instantaneous
power."

<https://www.google.com/#q="RMS+power">
681,000 hits on "RMS power".

[Phil Allison]

"Jeff Liebermann"
>>
>>> Ok, I yield to a higher authority. Heating power is average power:
>>> <http://www.eznec.com/Amateur/RMS_Power.pdf>
>>> However that doesn't stop nearly everyone from specifying RMS power.
>
>> ** There is no such quantity as " RMS power " if you are so stupid as
>> to
>>interpret the term literally.
>
> Which term should be interpreted non-literally?

** The term " RMS power " of course -

you fucking BLIND nut case ASSHOLE !!!!!!!!!!!!
----------------------------------------------------------

>>> So, why do people buy true-RMS voltmeters?
>>
>>** To get " true RMS " volts of course.
>
> Very good. But since there doesn't seem to be any correlation with
> heating power (despite using a thermocouple to do the measuring) and
> RMS volts or watts,

** Quite wrong - there is a very close connection.

> what does the meter indication on a true RMS
> voltmeter actually mean? Or is it just a mathematical abstraction?

** RMS voltage or current value = the DC equivalent value.

So the DC power formulas: " I squared R " and " V squared / R "
still apply in power calculations using AC voltages & currents.
---------------------------------------------------------------------------

** The RMS value of a voltage or current could hardly be more useful.

My god, you are SOOOOOO illiterate and SOOOOO retarded.

>
> Very perceptive and partly true.

** It's completely true.

You are the stupidest, most retarded, constantly lying fuckwit on the NG.

Get cancer and fucking DIE !



.... Phil

[Jeff Liebermann]

On Thu, 2 Jan 2014 13:00:20 +1100, "Phil Allison" <phi...@tpg.com.au>
wrote:

>"Jeff Liebermann"
>>>
>>>> Ok, I yield to a higher authority. Heating power is average power:
>>>> <http://www.eznec.com/Amateur/RMS_Power.pdf>
>>>> However that doesn't stop nearly everyone from specifying RMS power.
>>
>>> ** There is no such quantity as " RMS power " if you are so stupid as
>>> to
>>>interpret the term literally.
>>
>> Which term should be interpreted non-literally?

>** The term " RMS power " of course -

I thought you meant term as in the terms of an equation, where term
refers to the individual parts of the equation, not the whole. In the
same way, I use "term" to describe a single word, not a phrase. I
suggest you amend your proclamation by replacing the word "term" with
"phrase" as in:

"** There is no such quantity as " RMS power " if you

are so stupid as to interpret the phrase literally."

> you fucking BLIND nut case ASSHOLE !!!!!!!!!!!!

Yeah, I know. My eyesight is a problem and my hemorrhoids are driving
me nuts.

>> Very good. But since there doesn't seem to be any correlation with
>> heating power (despite using a thermocouple to do the measuring) and
>> RMS volts or watts,
>
>** Quite wrong - there is a very close connection.

<http://www.eznec.com/Amateur/RMS_Power.pdf>
On Pg 6 it says:
"The RMS value of power is not the equivalent heating power and,
in fact, it doesn't represent any useful physical quantity."
and:
"The RMS power is different than the average power, and therefore
isn�t the equivalent heating power. In fact, the RMS value of the
power doesn�t represent anything useful."

It would seem that the author finds average power different from, more
useful than, and closer to heating power. Perhaps we should change
the name from "true-RMS voltmeter" to "true heating average
voltmeter"?

"So it is written, so it shall be."
(Ramses in the CB DeMille version of the 10 Commandments).

(...)

> You are the stupidest, most retarded, constantly lying fuckwit on the NG.
> Get cancer and fucking DIE !

You'll not get rid of me that easily. I've already had cancer and
Obamacare promises to keep me alive forever.

[Phil Allison]

"Jeff Liebermann = retarded asshole "

>
>
>
>>>>> Ok, I yield to a higher authority. Heating power is average power:
>>>>> <http://www.eznec.com/Amateur/RMS_Power.pdf>
>>>>> However that doesn't stop nearly everyone from specifying RMS power.
>>>
>>>> ** There is no such quantity as " RMS power " if you are so stupid as
>>>> to
>>>>interpret the term literally.
>>>
>>> Which term should be interpreted non-literally?
>
>>** The term " RMS power " of course -
>

> I thought ...

** No you didn't - cos you are incapable of thought.

The quotation marks made my words quite *impossible* to misinterpret.

>>> Very good. But since there doesn't seem to be any correlation with
>>> heating power (despite using a thermocouple to do the measuring) and
>>> RMS volts or watts,
>>
>>** Quite wrong - there is a very close connection.
>

( snip more TOTALLY IRRELEVANT SHIT )

Leiberman - you are the stupidest, most retarded, constantly lying fuckwit

[Jeff Liebermann]

On Thu, 2 Jan 2014 13:56:15 +1100, "Phil Allison" <phi...@tpg.com.au>
wrote:

>> I thought ...

>** No you didn't - cos you are incapable of thought.

"I am, therefore I think". (My apologies to Descartes).
My presence always inspires thought.

> The quotation marks made my words quite *impossible* to misinterpret.

The contradiction between your quoted phrase and the misuse of the
word "term" makes it quite easy to misinterpret, which is why I asked
for clarification.

>( snip more TOTALLY IRRELEVANT SHIT )

Hardly. I cited an excellent analysis of the misuse of the phrase
"RMS power" to demonstrate my point and this is the best response that
you can offer? Surely, you can do better. Incidentally, go easy on
the overuse of spaces between words. The worlds supply of blank space
is limited. If depleted, will cause allthewordstoruntogether.

>Leiberman - you are the stupidest, most retarded, constantly lying fuckwit
>on the NG.

Is there some significance to the creative spelling of my last name?
Perhaps your are referring to someone else? Or are you simply
incapable of spelling my name twice the same manner? I shall ponder
the meaning of this obviously intentional creative spelling while I
take out the garbage and sort through the recycling. Surely, that
will inspire enlightenment.

Also, I would appreciate it if you would be a bit more creative in
your insults. Australia is famous for it's colorful insults, an
ability which you seem to be deficient. Perhaps these links will help
improve your vocabulary:
<http://www.youswear.com/index.asp?language=Australian>
<http://www.koalanet.com.au/australian-slang.html>
<http://en.wiktionary.org/wiki/Appendix:Australian_English_terms_for_people>
Unfortunately, I consider your spelling, formatting, capitalization,
grammar, and punctuation to be hopeless and beyond redemption. No
amount of remedial practice will help. I suggest you give up and hire
either a proof reader or a ghost writer. (No, you can't have mine).

>Get cancer and fucking DIE !

Sorry, but I've already had (prostate) cancer and failed to drop dead
in your requested manner. Obviously something is wrong with your
recommended procedure. Perhaps you could be a little more specific?

[William Sommerwerck]

"Jeff Liebermann" wrote in message

news:quc9c95b8el5pqevb...@4ax.com...

> OK, I yield to a higher authority. Heating power is average power:

> <http://www.eznec.com/Amateur/RMS_Power.pdf>
> However that doesn't stop nearly everyone from specifying
> RMS power.

Unfortunately, no.

> So, why do people buy true-RMS voltmeters? If they don't measure
> anything useful, why bother?

A fair question. Apparently, there was a time when AC power had a significant
percentage of harmonics (perhaps it still does), and engineers wanted to know
its "true" heating effect.

[William Sommerwerck]

"Jeff Liebermann" wrote in message

news:nsj9c95bm2ec1giaj...@4ax.com...

<http://www.eznec.com/Amateur/RMS_Power.pdf>
On Pg 6 it says:
"The RMS value of power is not the equivalent heating power and,
in fact, it doesn't represent any useful physical quantity."
and:
"The RMS power is different than the average power, and therefore
isn’t the equivalent heating power. In fact, the RMS value of the
power doesn’t represent anything useful."

> It would seem that the author finds average power different from,
> more useful than, and closer to heating power. Perhaps we should
> change the name from "true-RMS voltmeter" to "true heating average
> voltmeter"?

Jeff, you're misreading this. The author is saying //exactly// what I said.
(It's unfortunate he doesn't use a sine wave for his example, but the math
would then require integral calculus.)

Average power /is/ the heating power. (The rationale is that a resistor's
temperature is determined by the average power applied to it.) When we know
the RMS value of any repetitive waveform, we can compute its heating power by
squaring that voltage (current) and dividing (multiplying) by the resistor's
value.

Voltmeters (of all sorts) are usually calibrated to show the RMS value //of a
sine wave//. If the waveform differs, the value shown is wrong. One of the
advantages of a true-RMS meter is that all readings are "equivalent" in an
easily-comprehended way, regardless of the waveform -- even if that
"equivalency" has little practical usefulness. (If you want to know the
details of a waveform, you use a 'scope.)

I remember a Popular Electronics quiz with questions about how a voltmeter (at
that time, a moving-coil device) would read, depending on the waveform
supplied. A key point was that the deflection was proportional to the average
current flowing through the coil, but the meter was usually calibrated for the
RMS value of a sinewave.

[dave]

The question was why is audio power spec is half that of DC on/off
capability. It is because the device stays on all the time and because
the audio waveform causes more heating. Worry about the labels and fight
all you want.

[dave]

On 01/02/2014 04:05 AM, William Sommerwerck wrote:
> "Jeff Liebermann" wrote in message
> news:nsj9c95bm2ec1giaj...@4ax.com...
>
> <http://www.eznec.com/Amateur/RMS_Power.pdf>
> On Pg 6 it says:
> "The RMS value of power is not the equivalent heating power and,
> in fact, it doesn't represent any useful physical quantity."
> and:
> "The RMS power is different than the average power, and therefore
> isn’t the equivalent heating power. In fact, the RMS value of the
> power doesn’t represent anything useful."

> I remember a Popular Electronics quiz with questions about how a
> voltmeter (at that time, a moving-coil device) would read, depending on
> the waveform supplied. A key point was that the deflection was
> proportional to the average current flowing through the coil, but the
> meter was usually calibrated for the RMS value of a sinewave.

Why do you keep quoting notes from Llewelen? He wrote a modeling program
for wire antennas. We are talking about FETs.

I think AVG = RMS only if waveform is pure sinewave. Otherwise you must
use calorimeter or thermocouple to find true RMS.

[Bob F]

Phil Allison wrote:
> Leiberman - you are the stupidest, most retarded, constantly lying
> fuckwit on the NG.
>
> Get cancer and fucking DIE !

Plonk!

[Wond]

On Wed, 01 Jan 2014 18:49:17 -0800, Jeff Liebermann wrote:


> <http://www.eznec.com/Amateur/RMS_Power.pdf> On Pg 6 it says:
> "The RMS value of power is not the equivalent heating power and, in
> fact, it doesn't represent any useful physical quantity."
> and:
> "The RMS power is different than the average power, and therefore
> isn’t the equivalent heating power. In fact, the RMS value of the
> power doesn’t represent anything useful."
>
> It would seem that the author finds average power different from, more
> useful than, and closer to heating power. Perhaps we should change the
> name from "true-RMS voltmeter" to "true heating average voltmeter"?
>
> "So it is written, so it shall be."
> (Ramses in the CB DeMille version of the 10 Commandments).
>
>

(snipped)
ISTR it used to be a DC equivalent thing, ie, you need 6Vrms ac to
operate a 6VDC light bulb at spec.
I think Leak confused the issue when he branded those wonderful
audio amplifiers "RMS", thus putting the term in the realm of marketting.

[William Sommerwerck]

"dave" wrote in message
news:B4GdnYZ19saY4VjP...@earthlink.com...

>> I remember a Popular Electronics quiz with questions about how a
>> voltmeter (at that time, a moving-coil device) would read, depending on
>> the waveform supplied. A key point was that the deflection was
>> proportional to the average current flowing through the coil, but the
>> meter was usually calibrated for the RMS value of a sinewave.

> Why do you keep quoting notes from Llewelen? He wrote a modeling
> program for wire antennas. We are talking about FETs.

Who is Llewelen?


> I think AVG = RMS only if waveform is pure sinewave. Otherwise,

> you must use calorimeter or thermocouple to find true RMS.

RMS and average are the same only for square waves. True RMS can be computed
by analog circuits, one of which made its way in dbx devices.

[William Sommerwerck]

"dave" wrote in message
news:JIidnfhj6vc651jP...@earthlink.com...

> The question was why is audio power spec is half that of DC on/off
> capability. It is because the device stays on all the time and because the
> audio waveform causes more heating. Worry about the labels
> and fight all you want.

Exactly.

[Phil Allison]

"Bob Fuckwit ".


** Get cancer and fucking DIE !

Fuckwit plonker!

[Phil Allison]

"dave" <rick...@earthlink.net>


** FOAD - you autistic IDIOT !!!!!!

[Phil Allison]

"William Sommerwanker is a bullshitting ass."

>
>> So, why do people buy true-RMS voltmeters? If they don't measure
>> anything useful, why bother?
>
> A fair question.

** Wrong - it's a fuckwit question.

> Apparently, there was a time when AC power had a significant percentage of
> harmonics (perhaps it still does), and engineers wanted to know its "true"
> heating effect.

** Nonsense.

Any "moving iron" amp meter inherently reads "true RMS" values and they are
as old as the hills.

True RMS meters are mostly used to measure irregular signals like noise and
distorted current waveforms that exist with AC to DC supply conversion.

There is no way to compute these values ( from the peak or average rectified
value) as there is with sine or other regular waveforms.


.... Phil

[Phil Allison]

"Jeff Liebermann"

Leiberman - you are the stupidest, most retarded, constantly lying fuckwit
on the NG.

Get cancer and fucking DIE !

NOW !!!!!!!!!!!!

[Jeff Liebermann]

On Thu, 2 Jan 2014 11:21:15 -0800, "William Sommerwerck"
<grizzle...@comcast.net> wrote:

>> Why do you keep quoting notes from Llewelen? He wrote a modeling
>> program for wire antennas. We are talking about FETs.
>
>Who is Llewelen?

Author of Eznec antenna modeling software:
<http://www.eznec.com>

[Maynard A. Philbrook Jr.]

In article <nsj9c95bm2ec1giaj...@4ax.com>,
je...@cruzio.com says...

> > You are the stupidest, most retarded, constantly lying fuckwit on the NG.
> > Get cancer and fucking DIE !
>
> You'll not get rid of me that easily. I've already had cancer and
> Obamacare promises to keep me alive forever.
>

I'll be more than happy to put a Obama chia pet on your grave stone
for you.

I see Amazon has a deal for 28 bucks..

Jamie

[Maynard A. Philbrook Jr.]

In article <B4GdnYZ19saY4VjP...@earthlink.com>,
rick...@earthlink.net says...

>
> On 01/02/2014 04:05 AM, William Sommerwerck wrote:
> > "Jeff Liebermann" wrote in message
> > news:nsj9c95bm2ec1giaj...@4ax.com...
> >
> > <http://www.eznec.com/Amateur/RMS_Power.pdf>
> > On Pg 6 it says:
> > "The RMS value of power is not the equivalent heating power and,
> > in fact, it doesn't represent any useful physical quantity."
> > and:
> > "The RMS power is different than the average power, and therefore

> > isn?t the equivalent heating power. In fact, the RMS value of the
> > power doesn?t represent anything useful."

>
> > I remember a Popular Electronics quiz with questions about how a
> > voltmeter (at that time, a moving-coil device) would read, depending on
> > the waveform supplied. A key point was that the deflection was
> > proportional to the average current flowing through the coil, but the
> > meter was usually calibrated for the RMS value of a sinewave.
>
> Why do you keep quoting notes from Llewelen? He wrote a modeling program
> for wire antennas. We are talking about FETs.
>
> I think AVG = RMS only if waveform is pure sinewave. Otherwise you must
> use calorimeter or thermocouple to find true RMS.

AVG and RMS is not the same with sine waves..

Avg = 2/pi * peak Voltage.

And RMS is simply sqr( VP^2 / 2).
you'll notice the root his to look for the square not the
average of total voltage for example.

One can shorten that to say RMS = Vp * .707

Just think of a half round circle an draw and find the
area where you can evenly fit a square box in that half circle,
the value will be .707 times the Peak value of that circle.

Averaging ends up to be 2/pi = 0.637 * the peak voltage which
obviously gives you a different number..

And of course, no matter how you slice it, square waves at 50%
duty give you the same all around. AVG and RMS = peak.. cause there
is no slope in time for the avg and the nice square box I stated
fits perfectly in the already square wave for RMS. etc..

Jamie

[Phil Allison]

"Maynard A. Philbrook Jr."

>
> And of course, no matter how you slice it, square waves at 50%
> duty give you the same all around. AVG and RMS = peak.. cause there

> is no slope in time ...

** Too complicated.

Q. When you ( full wave) rectify a square wave what do you get?

A. DC.

With DC, the average, peak and RMS value are the same.

Is any proof really needed ?




..... Phil

[Maynard A. Philbrook Jr.]

In article <bimdj1...@mid.individual.net>, phi...@tpg.com.au says...

And where was I disputing that?

Jamie

[Phil Allison]

"Maynard A. Philbrook Jr."

> >
>> > And of course, no matter how you slice it, square waves at 50%
>> > duty give you the same all around. AVG and RMS = peak.. cause there
>> > is no slope in time ...
>>
>> ** Too complicated.
>>
>> Q. When you ( full wave) rectify a square wave what do you get?
>>
>> A. DC.
>>
>> With DC, the average, peak and RMS value are the same.
>>
>> Is any proof really needed ?
>>
>>

>

> And where was I disputing that?

** Yawnnnnnnnnn - wot a stupid straw man fallacy.

Read what I dam well wrote - fuckwit.



... Phil

[Shaun]

"Phil Allison" wrote in message news:bik2r7...@mid.individual.net...

Hey Phil;

I used to work at an Industrial and Instrumentation repair and Calibration
shop that was licensed by Beckman to repair and calibrate there DMMs. In
the good ones, the RMS converted used a thermal method to determine RMS
Voltage and Current. That was 18 years ago and I don't remember any details
except that they used thermal measurement on a heated element. I have
compared the reading on the Beckman - Then Wavetek - now I don't know if
anyone is still making them, to a Fluke RMS DMM at 60 Hz and DC and the
readings matched.
I have always heard that if you really want to know the real value, you have
to buy an RMS meter.


Shaun

[Phil Allison]

"Shaun"

>
> I used to work at an Industrial and Instrumentation repair and Calibration
> shop that was licensed by Beckman to repair and calibrate there DMMs. In
> the good ones, the RMS converted used a thermal method to determine RMS
> Voltage and Current. That was 18 years ago and I don't remember any
> details except that they used thermal measurement on a heated element. I
> have compared the reading on the Beckman - Then Wavetek - now I don't know
> if anyone is still making them, to a Fluke RMS DMM at 60 Hz and DC and the
> readings matched.

** No fooling...........

> I have always heard that if you really want to know the real value, you
> have to buy an RMS meter.

** That sort of nonsense *would* be said by someone who either owned an RMS
meter or was selling them.

Thermal RMS meters are virtually obsolete these days and have been replaced
by cheap analogue RMS to DC computation ICs in many hand held DMMs OR by
digital sampling computation in most DSOs.

The hand held kind have a limited measurement bandwidth compared to the
latter.

Depends what your needs are.

As Clint Eastwood might have said -

" Man's gotta know the limitations of his test equipment ".




.... Phil

[dave]

On 01/02/2014 04:07 PM, Maynard A. Philbrook Jr. wrote:
> In article <B4GdnYZ19saY4VjP...@earthlink.com>,
> rick...@earthlink.net says...
>>
>> On 01/02/2014 04:05 AM, William Sommerwerck wrote:
>>> "Jeff Liebermann" wrote in message
>>> news:nsj9c95bm2ec1giaj...@4ax.com...
>>>
>>> <http://www.eznec.com/Amateur/RMS_Power.pdf>
>>> On Pg 6 it says:
>>> "The RMS value of power is not the equivalent heating power and,
>>> in fact, it doesn't represent any useful physical quantity."
>>> and:
>>> "The RMS power is different than the average power, and therefore
>>> isn?t the equivalent heating power. In fact, the RMS value of the
>>> power doesn?t represent anything useful."
>>
>>> I remember a Popular Electronics quiz with questions about how a
>>> voltmeter (at that time, a moving-coil device) would read, depending on
>>> the waveform supplied. A key point was that the deflection was
>>> proportional to the average current flowing through the coil, but the
>>> meter was usually calibrated for the RMS value of a sinewave.
>>
>> Why do you keep quoting notes from Llewelen? He wrote a modeling program
>> for wire antennas. We are talking about FETs.
>>
>> I think AVG = RMS only if waveform is pure sinewave. Otherwise you must
>> use calorimeter or thermocouple to find true RMS.
>
> AVG and RMS is not the same with sine waves..
>

Then they never are the same?

[dave]

In television you calibrate the output power metering by operating into
a full power liquid cooled dummy load and measuring the temperature of
the coolant.

Using computational methods on amplifier input parameters is not the
preferred way to determine power (an efficiency factor must be assumed)
and you must ask the FCC for special permission to use the "direct method".

Dave the Re-Re

[Michael A. Terrell]

This is my favorite True RMS meter. Section three is a description
of how it works. The AC power line is anything but a clean sine wave.
Switching power supplies and older electronics with a single diode in
the power supply distort it, even more. The single diode causes a DC
component on your power, which confuses a simple analog meter. Three
phase is even worse, with all the harmonics on the neutral. There were a
lot of fires in office buildings and factories after the PC became
widespread. It used to be to code to use a smaller neutral on three
phase, than the tree phase lines. The harmonics caused the neutral to
overheat and in some cases, started fires.

I like this Fluke for many reasons, including the ability to read to
.01 dB variations in a signal. I used one to test the -3dB points on
video filters, up to 20 MHz. For anything higher I used a Boonton 9200
RF voltmeter.

Before someone smarts off, Video isn't just television. We produced
equipment with selectable bandwidth from DC>10 KHz to DC>40 MHz in 16
customer specified bandwidths. SDI digital video was 270 MHz, and HD is
even higher.

<http://www.ko4bb.com/Manuals/Fluke/Fluke_8920A_8921A_True_RMS_Voltmeter_Operation_and%20_Service_Manual_Oct78.pdf>


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

[Phil Allison]

"dave the autistic fool " <rick...@earthlink.net>

>
>> As Clint Eastwood might have said -
>>
>> " Man's gotta know the limitations of his test equipment ".
>
>

> In television you calibrate the output power metering by operating into a
> full power liquid cooled dummy load and measuring the temperature of the
> coolant.

** That would be for the actual transmitter on VHF or UHF - right ?

Same idea as using a glass of water and a thermometer test the power RF
power of a microwave oven.

Got SFA to do with the topic.



.... Phil

[Phil Allison]

"dave the pig ignorant autistic IDIOT "

> The question was why is audio power spec is half that of DC on/off
> capability.

** No it was not.

> It is because the device stays on all the time and because the audio
> waveform causes more heating.

** A maker's max dissipation spec for a semiconductor is not related to the
application.

It is only related to the device itself.

Normally, the figure given is for *ideal* operating conditions - like when
mounted on an infinite heatsink held at 20C.



.... Phil

[dave]

Odd. I thought Maximum values were on the data sheet. Anyway, a MOSFET
used as a switch makes less heat so it can have a higher current rating
than one used class AB.

[Michael A. Terrell]

'Safe Operating Area' is more important than individual maximums.

[Leif Neland]

Phil Allison skrev:

>
> Same idea as using a glass of water and a thermometer test the power RF power
> of a microwave oven.

Just don't leave the thermometer in the microwave oven with the power
on.

Measure the temperature of the cold water, then measure the time for it
to boil.

Preferably in a microwave-safe plastic container.

I measured the power of my previous oven to 230W...

Leif

--
Husk kￜrelys bagpￜ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

[mike]

On 1/4/2014 8:08 AM, Leif Neland wrote:
> Phil Allison skrev:
>>
>> Same idea as using a glass of water and a thermometer test the power
>> RF power of a microwave oven.
>
> Just don't leave the thermometer in the microwave oven with the power on.
>
> Measure the temperature of the cold water, then measure the time for it
> to boil.
>
> Preferably in a microwave-safe plastic container.
>
> I measured the power of my previous oven to 230W...
>
> Leif
>

When I did similar tests, I found the order of magnitude was right,
but the result depended on the shape and volume of the mass of water
and position in the oven.

It's easy to imagine that the microwaves bounce around and most of the
energy ends up
in the water. Wonder how accurate that model?
Wonder what the "official" water configuration is when they determine
the spec?

[Shaun]

"mike" wrote in message news:la9cdd$qov$1...@dont-email.me...

I've seen that method used before. I had an article about measuring
microwave oven power. You of course measure the increase in temperature
after running then microwave oven for a predetermine time at full power,
with a measured amount of water (distilled) in the direct center of the
oven. You could google it.

Shaun

[Phil Allison]

"Leif Neland"
> Phil Allison

>> Same idea as using a glass of water and a thermometer test the power RF
>> power of a microwave oven.
>
> Just don't leave the thermometer in the microwave oven with the power on.

** Should be OK with a glass tube and red liquid type.

> Measure the temperature of the cold water, then measure the time for it to
> boil.

** Bad idea.

Takes far too long, when boiling first begins is not clear and lots of heat
is lost to the air and evaporation.

> I measured the power of my previous oven to 230W...

** Using half a litre in a plastic jug for two minutes, I got the answer to
within 10% with a 700W rated oven.

Having a K-type bead thermocouple and digital temp meter made the job easier
too.



.... Phil

[Shaun]

"Phil Allison" wrote in message news:birqpr...@mid.individual.net...

You don't run it till boiling! once you get close to boiling point a lot of
extra energy is required to raise it further and make it boil. What you do
is run a glass of cold distilled water measured (temp and volume) in a
container, you could use several stacked Styrofoam cups for insulation and
cover the top with Styrofoam so that the heat generated does not escape and
run the oven till the temperature increase 20 to 50 degrees or so, then
measure the temp, the information will have an equation to convert degrees
rise to microwave power. Google the method - I haven't looked it up lately.

Shaun



.... Phil

[dave]

That is not how a calorimeter works. The load must be enclosed in liquid
and must perfectly match the RF output so it absorbs all the energy.
Then the temperature should be a very accurate way to measure power. It
must be a closed, water cooled load.

http://electro-impulse.com/techinfo/calorimeters.htm

[Shaun]

"Shaun" wrote in message news:Pk3yu.184114$Ks5....@fx08.iad...

Here is the Method from RepairFAQ from Sam:



7.1) Testing the oven - the water heating test


The precise number of degrees a known quantity of water increases in
temperature for a known time and power level is a very accurate test of
the actual useful microwave power. A couple of minutes with a cup of
water and a thermometer will conclusively determine if your microwave
oven is weak or you are just less patient (or the manufacturer of your
frozen dinners has increased their weight - sure, fat chance of that!)

You can skip the heavy math below and jump right to the final result
if you like. However, for those who are interested:

* 1 Calorie (C) will raise the temperature of 1 gram (g) of liquid water
exactly 1 degree Centigrade (DegC) or 9/5 degree Fahrenheit (DegF).

* 1 Calorie is equal to 4.184 Joules (J) or 1 J = .239 C.

* 1 Watt (W) of power is 1 J/s or 1 KW is 1000 J/s.

* 1 cup is 8 ounces (oz) which is 8 x 28.35 g/oz = 226.8 g.

* 1 minute equals 60 s (but you know this!).

Therefore, in one minute, a 1 KW microwave oven will raise the temperature
of 1 cup of water by:

T(rise) = (60 s * 1000 J/s * .239C/J * (g * DegC)/C)/(226.8 g) = 63
DegC.

Or, if your prefer Fahrenheit: 114 DegF.

To account for estimated losses due to conduction, convection, and imperfect
power transfer, I suggest using temperature rises of 60 DegC and 109 DegF.

Therefore, a very simple test is to place a measured cup of water in the
microwave from the tap and measure its temperature before and after heating
for exactly 1 minute on HIGH. Scale the expected temperature rise by the
ratio of the microwave (not AC line) power of your oven compared to a 1 KW
unit.

Or, from a Litton microwave handbook:

Heat one Liter (L) of water on HIGH for 1 minute.

Oven power = temperature rise in DegC multiplied by 70.

Use a plastic container rather than a glass one to minimize the needed
energy loss to raise its temperature by conduction from the hot water.
There will be some losses due to convection but this should not be that
significant for these short tests.

(Note: if the water is boiling when it comes out - at 100 DegC or 212 DegF,
then the test is invalid - use colder water or a shorter time.)

The intermediate power levels can be tested as well. The heating effect of
a microwave oven is nearly linear. Thus, a cup of water should take nearly
roughly twice as long to heat a specific number of degrees on 50% power or
3.3 times as long on 30% power as on full power. However, for low power
tests, increasing the time to 2 minutes with 2 cups of water will result
in more accurate measurements due to the long period pulse width power
control use by microwave ovens which may have a cycle of up to 30 seconds.

Any significant discrepancy between your measurements and the specified
microwave power levels - say more than 10 % on HIGH - may indicate a
problem.
(Due to conduction and convection losses as well as the time required to
heat the filament of the magnetron for each on-cycle, the accuracies of
the intermediate power level measurements may be slightly lower).

Shaun

[Jeff Urban]

I wanted to reply to this when you first posted it but I couldn't for
whatever reason. fucking thing. As you can see I am not posting from
google, which I no longer capitalize !!!! LOL

Anyway, what characterizes ANY part for the transmission of audio is
linearity. Even though the gate of a MOSFET is driven wildly different
than the base of a BPT, linearity of gain fro the very small signal to
the very large signal is the prime. We used to look at the hfe and HFE
gain curves of bipolars in the old days, not it is different.

Any kinds of spurious shit like oscillations would be no good in
switcxhers as well. the thing is, switchers somethimes have a gain curve
that is like, made to be on or off.

An audio transistor must operate in the analog range, that means the
gain curve should be as flat as possible through the operating current
range.

The same is true of a MOSFET.

[N_Cook]

Ah at last , thanks, a pertinent reply to my original question. I was
wondering if it was a larger area of silicon so the heat can migrate out
of the die quicker. So from what you say a non-audio switcher mosfet
could be used for analogue but the power rating would have to be derated
and no other qualification for such use, anymore than usual precautions
you would use for a switcher situation. I suppose the amount of derating
would then depend on the type of use bass amp v GP audio amp, dance
music v classical music etc

[Phil Allison]

"Nutcase Kook is yet another pig ignorant pommy cunt"


> Other than p channel in this case, same for BUZ901P nch
> eg BUZ906P 200V, 8A ,datasheet says
> "POWER MOSFETS FOR
> AUDIO APPLICATIONS"
> but also
> "FEATURES ... (for use in)
> HIGH SPEED SWITCHING ... "


** The Semelab app note makes it pretty clear there is a HUGE difference
between "switching" and audio ( ie lateral) power mosfets.

http://products.semelab-tt.com/pdf/ApplicationNoteAlfet.pdf


> Would a powerFET designed solely for high speed switching use and 125W
> rating be derated in power handling terms to only 50W say for linear 10 Hz
> use. Or secondary oscillation liability if paralleled up devices? or some
> other operational failing in audio use not found with smps say ?

** Yawnnnnnnnnnnnnnnn....

More brainless, fucking TROLLING !!!!!!!

FOAD you vile pommy cunthead.



.... Phil

> Ah at last , thanks, a pertinent reply to my original question.

** There is no possible answer to a question as wrong headed and stupid as
that.

So you will never get one.

FOAD you vile pommy cunthead.




.... Phil

[N_Cook]

On 05/01/2014 07:53, Jeff Urban wrote:

or on rereading . If an audio application can tolerate a certain amount
of cross-over distortion and general harmonic distortion then there is
no difference in powerfet useage type , up to some power level where
these distortions become too apparent.

[dave]

I learned what I needed to know to rebuild a fried Ampeg SVT3Pro. 4 [ea]
irfp9240s 4 [ea] irfp240s. Will oscillate itself to death. Must use a
scope and a light bulb current limiter to detect sudden current surging
due to rf feeding back. I think Vishay has some linear application notes
for these MOSFETs. They can be biased for very tiny crossover notch, but
the spec is bias for 800ma at the AC mains with no signal. Not terribly
efficient. But it's a bass guitar amp.

[mrob...@att.net]

Shaun <stereo...@gmail.com> wrote:
> When I did similar tests, I found the order of magnitude was right,
> but the result depended on the shape and volume of the mass of water

> and position in the oven. [...]

>
> Wonder what the "official" water configuration is when they determine
> the spec?

I don't know about a US Federal Trade Commission (or other agency, or
equivalent in other countries) test procedure; there probably is one but
I don't know it.

I know that older GE microwave ovens, in the little service information
sheet that was folded up inside the oven, gave directions on the test, a
GE part number for a beaker you were supposed to use, and I think a
third-party part number for the thermometer you were supposed to use to
measure the water temperature before and after. I think the water level
was marked on the beaker, and the service sheet said to put it right in
the middle of the oven. You didn't boil it, just heated it for a fixed
amount of time.

If I remember right, the criteria was something like "if the oven
produced between X and Y degrees temperature rise in the water, it's
within spec" - it didn't give you an answer in watts, just an acceptable
temperature range for that particular model oven.

Matt Roberds

[jurb...@gmail.com]

>"I was
wondering if it was a larger area of silicon so the heat can migrate out
of the die quicker."

That's not the crux of the matter. Power dissipation is power dissipation.
The suitability for audio use is the same as the suitability for any linear use.

Look at the spec sheet carefully, or actually link me to one. Better yet, I got a random one right here :

http://www.classiccmp.org/rtellason/transdata/irf430.pdf

Let that load in another tab for now. Power dissipation is power dissipation. Most of the time it is largely dependent upon the case style but there are other factors. The sheet in the link lists all three in the family at 75 watts.

I would like to see a spec sheet that gives a different Pd for pulsed and linear operation because if it does (not that I have ever seen one), it miust be figured a different way. For example RF power transistors are sometimes rated at their maximum capability in class C operation. This figure is useless to you for audio, or any linear application.

Now on that datasheet, look at figure 3 on the PDF page 4. Looing at the lines and the increments, it is a linear graph, not logarythmic. The lines drawn in the chart indicate the gain of the device. Ideally, those lines would be perfectly straight for linear use, but that is not achievable in real devices.
Even with the line not starting at zero, absolutely straight would be ideal, it doesn't matter where it starts.

As you can see, the line that represents 125C is the straightest, but you can't just run it it at 125C becasue you would have to derate for power dissipation so much that a pair of these 75 watt devices might get you 10 watts or some ridiculous low power like that. It would be very inefficient to say the least, and it would take class A to keep them that hot anyway.

Now, if you look at a MOSFET that is specifically only designed for switching, the "knee" in that curve is likely to be alot more pronounced, and that is a desirable characteristoic for a switcher because the idea is for it to spend as little time as possible in the linear region. No time at all would yield the most efficiency for a switcher. The only dissipation would be the leakage current when turned off times the voltage applied, and the voltage drop across the drain amd source times the current carried. One number of each is very low, therefore the power dissipation is very low at those times.

Then we have the time actually spent between states. That is where the real power dissipation comes in usually. What exacebates the situation is the fact that these devices frequently turn on faster than they turn off. This can cause problems in a totem pole arraingement obviously, or an inductive load as the voltage wants to go go go but the currentis not yet completely shut off off off. Thus the device can be and is frequantly optimized for switching.

This will make it perform very poorly in a linear application. In fact a long time ago I worked on a TV in which someone had replaced a video amplifier with an RF amp transistor that was designed to be a switcher. The result was a picture that had good blacks and whites, but almost no shades of gray, as if it was clipped. However, the actual video level was about right. Do you understand why ?

On a bipolar spec sheet you will find a similar curve but usually it looks upside down sort of from the gain curve on the FET data sheet here. It will have the current gain plotted against collector current. In that case you want the curve to be horizonatally as flat as possible for linear use. For switching, it is a whole different story.

At any rate, minding the divisions on the graph of course, of the three curves there in figure 3, the 125C line is best and the 25C line is worst. You will not get a perfectly straight line, but the closer you come the better. Ironically the -55C curve is not better, but that is just how these things are.

Now, if you want to parallel fets in a linear application, I can do that, but I need a case of beer. It is not as simple as just using source resistors because for that to work effectively the resistance value would be too high. I have a neat little drive circuit that not only accomplishes the current sharing accurately, but since it effectively shunts drive voltage, eliminates problems with storage time (?), the turning off slower than turning on thing. That can cause alot of problems.

Even in switching circuits, if you are heading for the high frequencies you have to optimize the drive to make sure the damn thing turns off in time. This requires pretty much shorting out the charge on the gate to source capacitance. Driving it linear is not exactly the same, but some of the same principles apply. In more modern devices you don't have to jump through as many hoops. Semiconductor manufacturers do improve their products and lessening drive requirements in all ways is considered an improvement as it is attractive to engineers who have alot to say about which devices are chosen and therefore bought.

This is long enough. I probably will never catch all the typos...