Driver to drive?

[Jonathan Kirwan]

On 6 Nov 2004 02:10:10 GMT, Jim Yanik <jyanik@abuse.gov.> wrote:

Jonathan Kirwan <jkirwan@easystreet.com> wrote in
news:ngkno01d1e45oukt4buc8jrc8s8dk10fog@4ax.com:

This Bush administration signed a deal with Israel for some 500
"bunker busters." Also, the US just recently transferred the first of
100 F-16Is to Israel; these have the extended fuel tanks. My guess is
that, in *this* next short period of two or three years, we may see an
Israeli attack on Iran and a drastic deepening of US active
involvement in the aftermath. If we found it difficult to think of a
viable exit strategy last year, it may be even more difficult to think
about soon.

Well,the world is very lucky that Israel destroyed IRAQ's nuclear
reactor;otherwise,Saddam would have had nuclear weapons,and probably would
have used them(or given one to terrorists for use against Israel or the
US).But since Iran is using Hezbollah against Israel,they have a legit beef
with Iran,and an understandable reason to not see Iran develop a nuclear
weapon.Iran would likely give terrorists a nuclear weapon.They are unstable
enough for that to be a real,valid threat.

Not my argument. I just stated what appears inevitable and you haven't taken
any issue on that point. So I assume it still stands.

Jon

 

[Al Borowski]

So, you see? It's our _duty_ to overthrow the Cheney/Rumsfeld cartel and
their dummy, whom I'm understandably reluctant to say the name of in
such a "subversive" and yea verily "treasonous" post as this.

The elections are over, is there any chance we can stop the political
posts sometimes in the nest six months?

Al

Cheers!
Rich

 

[john jardine]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:%Qfid.4422$zx1.871@newssvr13.news.prodigy.com...

Hi John,

(My Krohn-Hite 3342 switched, lo-pass hi-pass, lab filter goes down to
0.001Hz. Biggest caps in there seem 10uF polyprops, using discrete
semis!)
regards


Weren't these hand-built and the size of a Radio Flyer cart?

Regards, Joerg

http://www.analogconsultants.com

Suspect that was the previous model. This is rack mount about 5" high.
0.001Hz to 100kHz, 2 identical channels of brickwall LP/HP, decade switch
settable. Magnificent piece of gear but oh so rarely used.
It's just *too* good!. The filtered signal it puts out is so enticing that
I've been drawn in and wasted time trying to approach a similar performance
using a few opamps. Totally uneconomic.
Same with power supplies. I much prefer to design and test using rubbish
PSU's. Good ones supress truths that Sods law will later reveal on site.
My experience is that lab' grade kit is great for checking out novel ideas
but a millstone if used in designing gear for customers in a real world.
regards
john

 

[Pooh Bear]

Rich Grise wrote:

On Fri, 05 Nov 2004 21:49:15 +0000, Pooh Bear wrote:

Pinchy wrote:

I am building a waveformgenerator. To increase the output current I
intend to use a push pull class amplifier (NPN - PNP) in the feedback
loop of the last opamp. Hence it has to go up to 100 kHz I am looking
for the most recommended transistorset to build this stage. It should
be able to provide up to 15 V / 50 ohm (output resistance) = 300 mA in
order to get an automatic shortcut protection circuit (50 ohm acting
as a load)

The combination BC457 - BC557 (100 mA) is not suitable. The other
BD139 - BD140 (5A) is giving trouble in high frequency range as the
junctions of these are getting pretty big. The last option is a BC141
- BC161 (1A) but those are getting pretty old. Has anyone a better
idea (European parts) ? Is it usefull to bypass the collector - base
junction with Schottky diodes (as in digital 74LS, ALS, AS, ...) to
inprove the discharge speed of the collector junction ?

What's the special requirement for 'pro-electron' designation type devices
exclusively ? Nothing really good that I can think of.

Scared to use anything that starts 2N ? MJ even !

Probably availability of Right- or Left-pondian parts.

I suspect from the grin that you know that's a non-issue. I'm in the UK and only
use a couple of BC parts regularly in my designs. They happen to be widely used
worldwide.

The OP may be less well versed in component availability I suspect.

Graham

 

[Kevin Aylward]

Terry Given wrote:

Kevin Aylward wrote:

Rich Grise wrote:

On Wed, 03 Nov 2004 12:56:43 +0000, Kevin Aylward wrote:
[about FET current sources]

Vt\Vp can vary several hundred percent so this one off batch means
nothing. You can expect huge variations. Your "design" is an
accident waiting to happen.


So, in other words, are you saying, as was I, that coming off the
line, even with care in the production process, there is still so
much variation in the cutoff current


V Pinch off/V Threshold and Idss


that makes it such that you'd have
to individually test each unit? (which, of course, jacks the price
up a bunch)


Yes. Unless, of course your design can stand say, at least a
+100%/-50% variation in current.

Kevin Aylward

Which it probably cant, not if you wanted a "constant" current source
(sink) in the first place.

This is actually a different issue. A constant current can be constant,
yet vary

The constant bit refers to its ability to remain fixed with respect to
its applied voltage.

Although I suppose if I tried hard enough I
could think of an application where the stability was important but
not the magnitude, just not off the top of my head.

Driving a zener is one application where its actual magnitude might not
be important over a wide range. This would be for obtaining a very good
PSRR on a reference.

How stable over temperature Kevin?

Er... Data sheet...

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.

 

[Rich The Philosophizer]

On Sat, 06 Nov 2004 17:02:12 +1300, Terry Given wrote:

why are tits common-place on TV in the US, but a penis is rarely, if
ever, seen?


You don't know what you are talking about here. Ratch
perhaps not in that regard, although all the cable porn I watched in
hotels on business trips showed titties galore but nary a penis to be found.

Oh, well, yeah, on pay TV. On-air TV still can't show tits. And
ther's no dicks because the guys that pay for cable TV aren't
interested in seeing dicks, since they're all homophobic. ;-)

Cheers!
Rich

 

[John Fields]

On Thu, 04 Nov 2004 07:45:09 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Thu, 04 Nov 2004 08:05:29 GMT, john_c@tpg.com.au (John Crighton)
wrote:

[snip]

You are confusing the term "union" with employee.
Employees may go on strike whether they are union members or not.

[snip]

Around here, in Arizona, striking by non-union types will simply get
you fired... pretty much the same rules as allowed Reagan to fire the
flight controllers.

---
Slight difference in that the ATC guys were Federal employees and as a
condition of their employment had to sign a non-strike agreement.
When they tried it, Reagan just booted them out because of their
violation of the agreement. Exactly the right thing to do, IMO.

--
John Fields

 

[legg]

On 4 Nov 2004 03:35:40 -0800, "Radiohead"
<p.r.bradbrook@bradford.ac.uk> wrote:

I've just started to learn about matrix converters as part of my
university course, and I've been asked to decide which is the best
device to use in a matrix converter out of MOSFET, IGBT, Thyristor.

It looks to me like MOSFETs & IGBTs are the best but I'm not sure which
is the right answer. I'm thinking it might depend on the voltage &
current, and so there is no answer that is correct for all cases. Is
this right?

If any one has any experience of this I would appreciate your coments.
Many thanks.

When reverse voltage stress is applied, the mosfet looks like a
forward biased diode, the thyristor blocks the voltage, and the IGBT
may go pop (though there are some IGBTs that do reverse-block safely).

Funny thing about thyristors is that they tend to stay on after you
remove gate drive, so you could be restricted to the input frequency
as the highest conversion (and output) frequency when you use them,
unless there are auxiliary methods of shutting them off. Not all loads
like to see low frequency ripple.

There are a host of references that can be googled.

RL

 

[Spehro Pefhany]

On Thu, 04 Nov 2004 11:52:19 -0600, the renowned John Fields
<jfields@austininstruments.com> wrote:

Without the permission of the union, no single member or group of
members can go on strike, and when the _union_ decides to go on strike
it does. There _is_ the formality of the ratification of the action
by the members of the union, but that's usually a fait accompli since
disagreement with union _management_ (LOL!) is severely frowned upon.

I believe that it's considered giving the union negotiating leverage,
so the vast majority votes in favor of a strike, even though they
really hope it will be settled before the strike and resulting damage
occurs.

Bottom line is, the union wants to wrest all control from the company
and wants to make sure those dues keep rolling in.

The first priority for any organization- survival of the organization,
the second- growth of the organization. Then comes whatever they are
supposed to be doing. Japanese unions seem to be different.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Terry Given]

Daniel Haude wrote:

On Fri, 05 Nov 2004 18:29:09 GMT,
Ratch <Watchit@Comcast.net> wrote
in Msg. <VDPid.572820$8_6.82085@attbi_s04

Hey Ratch, I think you're having such a hard time in this argument because
so far you've failed to properly define the terms "aberrant" and "deviant"
on which you base your argument. But let me help ypu and look it up:

aberrant:
1. Deviating from the proper or expected course.
2. Deviating from what is normal; untrue to type.

deviant:
Differing from a norm or from the accepted standards of a society.

Well, there you are. It all boils down to your personal matter of taste,
or to some very vague concepts as "accepted standards of society".

Hey, just recently I met someone who rides a monocycle to work every day
(in public!). This behavior certainly fits the above definitions of
aberrant and deviant. Does that mean that public monocycling should be
banned?

--Daniel

Fucking monocyclists, its THEIR fault. Banned? kill them all I say, and
leave their severed heads on poles as a warning to all propsective
deviants - CONFORM. The neighbourhood watch officer will be around to
collect urine samples in the morning.

Cheers
Terry

 

[John Miles]

In article <b83b4153.0411031623.75591849@posting.google.com>,
burnboy1000@hotmail.com says...

I've looked in my textbooks and a bit online but so far haven't found
useful tables of component values for pi-networks. I agree with you
all that I should have been using input and output impedances. I've
updated my diagram and formulas to suit.

Pi networks are sort of old-school. They were popularized by Collins
and other manufacturers back in the days when vacuum-tube power
amplifiers ruled the ham-radio roost. They could match the final
amplifier's relatively-high plate impedance to a low-Z antenna,
providing low-pass filtering at the same time. I don't see them
mentioned very often in current literature.

The ARRL Handbook would probably be a good place for further research on
pi networks. If you can find the old "Single Sideband Principles and
Circuits" volume by Sabin, Bruene, and Schoenike, it will probably go
into more detail. Not sure what else to recommend as far as books you
can actually find outside of a well-stocked university library.

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

 

[Ratch]

"Daniel Haude" <haude@kir.physnet.uni-hamburg.de> wrote in message
news:slrncop7dc.5ou.haude@kir.physnet.uni-hamburg.de...

On Fri, 05 Nov 2004 18:29:09 GMT,
Ratch <Watchit@Comcast.net> wrote
in Msg. <VDPid.572820$8_6.82085@attbi_s04

Hey Ratch, I think you're having such a hard time in this argument because
so far you've failed to properly define the terms "aberrant" and "deviant"
on which you base your argument. But let me help ypu and look it up:

aberrant:
1. Deviating from the proper or expected course.
2. Deviating from what is normal; untrue to type.

deviant:
Differing from a norm or from the accepted standards of a society.

Well, there you are. It all boils down to your personal matter of taste,
or to some very vague concepts as "accepted standards of society".

In the context of minority behavior, it is society as a whole, not just
you or I that will determine how the definition of deviancy will be applied.
We, as individuals, can only hope to influence the rest of society to
consider and accept how the definition will be implemented.

Hey, just recently I met someone who rides a monocycle to work every day
(in public!). This behavior certainly fits the above definitions of
aberrant and deviant. Does that mean that public monocycling should be
banned?

Evidently not. Society has accepted two wheeled power vehicles as a
minority method of transportation, and has allowed licensing and posted
rules for their operation. I think that power monocycling is still banned
on public roads, but I could be wrong about that. It is up to the power
monocyclists to try to convince the majority of society to allow them to
operate. The public does not seem to have any problem with unpowered
cycles, both single, double, and triple, however. Ratch

--Daniel

--
"With me is nothing wrong! And with you?" (from r.a.m.p)

 

[Fred Bloggs]

Ratch wrote:

In the context of minority behavior, it is society as a whole, not just
you or I that will determine how the definition of deviancy will be applied.
We, as individuals, can only hope to influence the rest of society to
consider and accept how the definition will be implemented.

ffffffffffuuuuuuuuuuuuuccccccccccckkkkkkkkkkkkkk U! If there's something
you don't like about my behavior, you may go to hell.

 

[Radiohead]

Many thanks for the guidance, it's much appreciated!

 

[Paul Burridge]

On Sat, 06 Nov 2004 01:35:29 GMT, Rich The Philosophizer
<null@example.net> wrote:

Well, I have heard that they have a ritual where they mutilate
their male children.

There was a program on TV 'bout it 2 nights ago. In this case, the
snip went too far and the poor boy ended up with no dick! So he was
raised as a girl until age 13 when it all came out. He's been screwed
up ever since. I think it's time all forms of genital mutilation were
criminalised. The situation with young girls in central Africa is
equally despicable. A job for the International Criminal Court,
perhaps?
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Fred Bloggs]

Paul Burridge wrote:

On Sat, 06 Nov 2004 01:35:29 GMT, Rich The Philosophizer
null@example.net> wrote:


Well, I have heard that they have a ritual where they mutilate
their male children.


There was a program on TV 'bout it 2 nights ago. In this case, the
snip went too far and the poor boy ended up with no dick!

You do know that the original ritual called for the circumciser to
staunch the blood flow with his mouth? And then someone was supposed to
eat the foreskin- not sure who.

 

[Kevin Aylward]

Tilmann Reh wrote:

Kevin Aylward schrieb:

I would *not* suggest MOSFETs due to their large G/S capacity,

This is misleading. A bipolar transister with an ft of say, 200Mhz,
at 300ma has a Cin of around 10nf, to wit.

Not in emitter follower circuit.

Ho hummm...

Sure, one can *sometimes* take advantage that Can't = Cin/(1+gm.Zl), but
again, this is misleading when switching as *fast* as possible. The
reality is that the load capacitance is large, causing essentially, a
s/c for the initial transient. That is ZL is, essentially, zero.
Whatever cin is directly, is what you need to drive if you trying for
the ultimate in speed. Of course, I don't know what the posters
requirements are. This is only a suggestion.

And, BTW, the 300 mA will flow only in case of overload.

I have no idea what the circuit is. I am only making suggestions in
general.

A small mosfet will be much, much lower than this.

A small MOSFET won't be able to handle the power dissipation.
A larger MOSFET will have large capacities, which must be driven
by the OPamp or separate driver stages.

Ho hummm...A "large" mosfet able to take the power will usually still
have much lower capacitances than a bipolar. It why the standard device
in SMPS are mosfets, not bipolar. You can switch them an order of
magnitude faster. End of story.

and since you have to drive their gates far beyond the supply
voltage if you use them in source follower circuit.

Yes, but you can use a capacitive bootstrap on both sides of the
driver.

Driven by the OPamp directly?

No idea what you mean here. One has output capacitors feeding the drive
supply rails in a suitable manner.

Using rather modern BJTs sounds like the more effective answer
to the OPs question.

Maybe, maybe not.

Well, I am currently playing around with simulations of an audio amp
using state of the art bipolar (ft=50Mhz, 15A, 230V, 150W) and its a no
contest. Mosfets switch much faster. I can get 1000V/us (500W @8ohms)
with mosfets, only about 100V/us with bipolar.

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.

 

[Klaus Vestergaard Kragelu]

"Kevin Aylward" <salesEXTRACT@anasoft.co.uk> wrote in message
news:jc6jd.29818$Fu2.1103@fe1.news.blueyonder.co.uk...

Tilmann Reh wrote:
Kevin Aylward schrieb:

I would *not* suggest MOSFETs due to their large G/S capacity,

This is misleading. A bipolar transister with an ft of say, 200Mhz,
at 300ma has a Cin of around 10nf, to wit.

Not in emitter follower circuit.

Ho hummm...

Snip

Ho hummm...A "large" mosfet able to take the power will usually still
have much lower capacitances than a bipolar. It why the standard device
in SMPS are mosfets, not bipolar. You can switch them an order of
magnitude faster. End of story.

Not according to my oppinion. The reason MOSFETs are used in switch-mode
supplies are more that they are easy to drive (no gate current). Ofcourse
the low capacitance is a second order effect

Cheers

Klaus

 

[Rich The Philosophizer]

On Sat, 06 Nov 2004 18:04:33 +0000, Jim Yanik wrote:
....

We have not even applied any sanctions yet.Once Iraq settles into
democracy,

You mean, like Vietnam did?

Thanks,
Rich