Driver to drive?

[Fred Bartoli]

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> a écrit dans le message de
news:jYAdw$MxqZZBFwjV@jmwa.demon.co.uk...

I read in sci.electronics.design that Mark <Mark@?.?> wrote (in
nieam09thhf22ius6ce1dgd91qukfb7sen@4ax.com&gt about 'Amplifier
Oscillating Help Please', on Thu, 7 Oct 2004:

I also have a 1Mfd cap on the
output.

That sounds like a problem to me. What do you mean 'on the output'? If
you have '1 uF plus a low resistance' connected to ground, the op-amp
will very likely oscillate.

I just designed some low noise supplies where the opamp output is loaded by
1R-5uF or 1R-10uF LPFs.

While it's quite simple, I had hard time to make my clients understand why
it's perfectly stable and also to make them understand we had to lower the
resistance down to 0.1R before stability became an issue. And also that, at
0.2R, lowering the cap reduced magins while rising its value rendered the
circuit more stable. They were finally completly puzzled when I showed them
that at 0.1R-5uF (barely 15° phase margin) a neat solution to the pb was to
use the decompensated version of the opamp.


--
Thanks,
Fred.

 

[Winfield Hill]

Wouter van Ooijen (www.voti.nl wrote...

I think you misunderstand my question. I want to know the
interpretation of the symbol. A square with a wedgie in it, with a
line going into the wedgie. Is that supposed to denote a
positive-edge-triggered thingie or a negative-edge-triggered thingie?
Or does the answer depend on the kind of thingie, D or JK FF? Or dies

It's positive-edge triggering.

.. positive negative
.. ___ ___
.. | | | |
.. ---|> | ---o|> |
.. |___| |___|
..


--
Thanks,
- Win

(email: use hill_at_rowland-dotties-org for now)

 

[Dave VanHorn]

Remember: Your friends can rile you a lot better (and far more
easily) by making you think you are bugged than by bugging you.

Indeed.. drop by the library, and pick up some books on espionage.
Full of fun ideas

--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR

 

[Rich Grise]

On Thursday 07 October 2004 01:17 pm, Andy did deign to grace us with the
following:

Hi,

I designd a dataloggor which need to give me temprature en presure. I
used an atmel 8051 microcontroller to control the sensors and sending
the data to pc or storing it on chip memory.

The temprature is dedected with a maxim ic, which is using 1 - wire
protocol to communicate. I know there is a IC that translate UART
(RS232) to 1 - wire. But I'm already using my one an only UART to
communicate with the PC.
So the only solution is to write my own 1 - wire protocol.

Does somebody have a easy to understand application note. Or more
detailed: the bitrate, how to code the date, etc.

The easiest would be to look at the data sheet for the maxim IC that's

sending the data. They might even have code snippets.

Good Luck!
Rich

 

[Rich Grise]

On Thursday 07 October 2004 12:46 pm, Dirk Bruere at Neopax did deign to
grace us with the following:

John Woodgate wrote:
I read in sci.electronics.design that Dirk Bruere at Neopax
dirk@neopax.com> wrote (in <2sku50F1lhop8U3@uni-berlin.de&gt about
'Whmisy: If This NG Were a Zoo, WHere Would ou Be?', on Thu, 7 Oct 2004:


I think I'll go for rat.


White in the petting zoo or brown in the sewer?

Brown - in the petting zoo.

Careful you don't take a wrong turn and end up in the "snake snacks"

bin. ;-)

Cheers!
Rich

 

[Rich Grise]

On Thursday 07 October 2004 11:39 am, John Woodgate did deign to grace us
with the following:

I read in sci.electronics.design that Winfield Hill
Winfield_member@newsguy.com> wrote (in <ck3d5e0ckh@drn.newsguy.com&gt
about 'The Rational Mind of Fred Bloggs', on Thu, 7 Oct 2004:

You can take you Hint and shove it up your ass.

Win, don't demean yourself. Rise above it. Take lessons from Rich. (;-)
--

Um, ahem. It's not that I "rise above it," I'm quite comfortable here
on the planet, actually. ;-) I yawn, belch, and fart with the guys and
everything, I just can't see continuing to play with guys who seem to
only want to play "call me $NAME again."

Mentally, (and "spiritually") of course, I'm all metaphysical, but like
the guru said, "Before enlightenment, chop wood, carry water. After
enlightenment, chop wood, carry water." ;-)

Thanks!
Rich

 

[Rich Grise]

On Thursday 07 October 2004 12:14 pm, John Woodgate did deign to grace us
with the following:

I read in sci.electronics.design that John S. Dyson <toor@iquest.net
wrote (in <ck3eut$okr$3@news.iquest.net&gt about 'The Rational Mind of
Fred Bloggs', on Thu, 7 Oct 2004:
Hatred is
problematic.

No, it's not 'problematic'. That's 'touchy-feely' woolly-mindedness.
Hatred is a manifestation of evil, and the simplest way to explain what
the concept of 'evil' is.

Hatred does no good to anyone, and in particular it distorts the
thinking of the hater, while either having no effect on the hatee or
resulting in assaults on him/her or his/her interests.
--

By Jove, I think he's got it!

Cheers!
Rich

 

[Rich Grise]

On Thursday 07 October 2004 12:17 pm, John Woodgate did deign to grace us
with the following:

I read in sci.electronics.design that Fred Bloggs <nospam@nospam.com
wrote (in <41653DFC.2050606@nospam.com&gt about 'The Rational Mind of
Fred Bloggs', on Thu, 7 Oct 2004:
This is not quite true- and you should shut your damned mouth when you
don't have a hint in hell what's going on here.

And I love you, too, Fred. Do Democrats support free speech? Even
allegedly uniformed free speech?
--

Well, it's fairly well established that the Republicans like uniformed
[sic] free speech. ;-)

I like to quote my Dad (RIP): "I may not agree with what you say, but I
will defend to the death your right to remain uninformed."

I do have to admit I haven't been really faithful about following his
advice, but having discovered the new paradigm, I've become quite the
fanatic.

Thanks,
Rich

 

[Rich Grise]

On Thursday 07 October 2004 07:28 am, Winfield Hill did deign to grace us
with the following:

Fred Bloggs wrote...

You're way too dumb to see it- but you're witnessing the beginning
of the end. You are not so old that you will escape experiencing the
horrific chaos about to unfold. The upside for you is that you will
not last three days- you're not tough enough to survive.

Whatever are you talking about, Fred?

Sounds like the rise of the Fourth Reich and the _Final_, Final War.

I'm just sayin'!

Cheers!
Rich

 

[Ken Smith]

In article <ck38ft02va0@drn.newsguy.com>,
Winfield Hill <Winfield_member@newsguy.com> wrote:

Ken Smith wrote...

[...]
"Simple matter" may be mis-stating it a bit. 150W spikes are not a
simple matter to deal with in most components. The idea isn't
complex but finding components can be.

No, thankfully that's not completely true. 150W power levels are
easy to handle in small parts for even millisecond time scales. Or
are you saying finding manufacturer's data is not easy?

Yes its getting the data on the components I can get or getting the
components from those who spec the pulse power.

Yes, that's
correct, you have to create your own data. The physics is simple
and well understood, and the component's thermal mass, once you've
determined it, can be relied to remain the same in production even
though it's not a specified parameter.

In resistors, it is often the thermal mass of the resistive element that
really matters. In other designs, I determined that the pulse was over
before significant heat got away from the element.

I have found it useful to
create spice models of transient thermal diffusion to determine the
maximum temperature reached during an event, using many elements of
thermal mass and thermal resistance. In cases where I could measure
the temperature with time (avalanche breakdown, whose voltage has a
temperature coefficient) the data matched my spice modeling.

Good idea. When I get the data I need, I can do this, I think.

I've used LT-Spice to solve static heating cases.

If I use a power MOSFET, I really need to monitor the voltage in
some way so that an attempt to pull the output outside the rails
causes the MOSFET to be shut off.

Correct, no matter what elements you use. I haven't suggested
power MOSFETs because the p-channel types stop at 500V, and you'd
be required to design a fast series circuit, which is painful,
or use two n-channel parts back-to-back, which requires a fast
isolated gate drive, which is possible but painful as well.

For the hard to do MOSFET, I can have slow gate drive for normal operation
and something running on the current sense resistor to override it in
overload. Take this circuit for a starting place:

ASCII ART:

!!--- +15V
OPTO ----/\/\/------!!
! !!---
! !
\! !
NPN !-------!
/! /
! \
! /
! !
----------+----------- To load

Even if the OPTO is slow, the NPN can take the bias away from the MOSFET
quickly. If I can come up with a replacement for the NPN transistor that
limits the current to 0.25A unless the load tries to pull the output below
the -15V rail. Below the -15V rail, the circuit would turn the MOSFET
completely off.
--
--
kensmith@rahul.net forging knowledge

 

[Ken Smith]

In article <ck3ag20434@drn.newsguy.com>,
Winfield Hill <Winfield_member@newsguy.com> wrote:

Ken Smith wrote...
[...]
This is 60V, but the maximum rated current is 3A, and that's for
continuous operation. So it would appear they can handle much higher
voltages for a short time. They also say,

I think it is that I have to hold the current below lets say 3A while the
device trips and then the voltage can rise to 600V.

CAUTION : FRH devices are not intended for continuous use of Line Voltage
such as 120 VAC~ 600VAC and above.

OK, not intended for continuous use. That implies intended for short-
term use. It's your task to find out how short, with measurements and
with modeling. These parts may well provide the basis for the most
difficult-to-handle aspect of an effective solution to your problem.

That was what I did with the BC parts. They survived a 440VAC input.

--
--
kensmith@rahul.net forging knowledge

 

[John Woodgate]

I read in sci.electronics.design that Genome <genome@nothere.net> wrote
(in <sqi9d.150$0%.146@newsfe6-win.ntli.net&gt about 'Looking Thru John
Kerry's Rose Colored Glasses', on Thu, 7 Oct 2004:

FUCK OFF
FUCK OFF
FUCK OFF
FUCK OFF
FUCK OFF

Yes, but what do you REALLY think? (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Norm Dresner]

"Mark" <Mark@> wrote in message
news:nieam09thhf22ius6ce1dgd91qukfb7sen@4ax.com...

On Thu, 07 Oct 2004 08:55:27 GMT, "Norm Dresner" <ndrez@att.net
wrote:

Mark wrote:

I am more of a digital man than an analogue one. I need help please,
the set-up is as follows, I have an serial ADC output feeding an
Op-Amp feeding a 12V 40W Amplifier IC. The amp works in Class H to get
the output. The trouble is I am getting HF oscillations at high volume
levels (in rythem with the signal). You can see them on a scope, I
have a common ground plane for all of the circuit, I have thick tracks
going to the high power parts, I have a choke in line with the 7805
regulator for the logic. The Op-Amp is powered from the 5V logic line
(I only need 2V swing to drive output amplifier fully. I have tried
putting a heavy choke to the power supply input of the power amplifier
section, which did not help, I have tried putting a cap across the
input to the output amp, this helped a lot (with some decrease in
treble) but did not cure it completely, I have tried doubling the
values of the two caps used for the class H operation, did nothing,
tried doubling the power supply reservoir capacitor, this did nothing,
tried isolating the OP-Amp power supply with a diode and a smoothing
cap, this did nothing, also tried adding a choke to the opamp supply,
again nothing.

The thing that is throwing me is my Tektronics scope. When I put a
heavy connection wire between the Ground input of the scope and the
Ground of the circuit under test, and I put my probe onto the Ground
of the circuit under test (even at the same point where the heavy
ground wire is, I can see the HF oscillations on the screen. Trouble
is this is throwing me off the scent as to where the Oscillations are
coming from.

Can anybody give me some pointers please, I am starting to think that
I should have not taken on an Analogue design. Any web sites giving
hints and tips on this subject would also be appreciated.


I didn't see in all of this a characterization of the Op Amp's load. Is
it
capacitive? Inductive? What OpAmp is it?

Its a LF353N, I have on the negative input a 10K resistor 10Mfd
capacitor chain, going down to ground with a 470K resistor going from
the output back to this input. My signal input goes in via a 1 Mfd
cap then held to half way between the supply lines by two 100K
resistors before going to the positive input, I also have a 1Mfd cap
on the output. As said before the OP-Amp is powered from the 5V logic
supply via a 1N4148 diode and 10Mfd capacitor.

Do you have any overall HF feedback around the Op Amp? Depending on the
frequencies you're interested in (I'm assuming something near the audio
range) 15-30 pF shouldn't change the frequency response too much and
would
be diagnostic.

Where would I place this, please?

Feedback is usually negative to stabilize the amp and is connected from
the output to the negative input. Assuming you have the 470K resistor doing
the feedback between the output and the negative input, you'd parallel this
resistor with a small (value) capacitor.

Now, as others have asked you, what exactly do you mean by a 1uF capacitor
on the output? From the output to ground? NO! Most Op Amps are very, very
sensitive to capacitive loading. even a nF or two can be fatal.

Because you're a "digital man" you immediately think that output problems
like HF oscillation are caused by power supply issues but there are
analog
circuits that delight in oscillating. In particular a complementary pair
at
the output of an analog amp is a good example, especially if they're
MOSFET.

Norm

Norm

 

[Ken Smith]

In article <1097152669.621401@cswreg.cos.agilent.com>,
Ian Buckner <Ian_Buckner@agilent.com> wrote:
[...]

Ken, you can "open" a relay in a very short time, tens of microseconds
or less. The trick is to have the relay coil rated at 500V (rating,

I also need contacts that are rated to 600V. They tend to be biggish and
thus slower moving. The fastest I've ever seen a relay actually operate
in was on the order of 1mS not 10uS. What relay are you thinking about?


--
--
kensmith@rahul.net forging knowledge

 

[Ken Smith]

In article <heeam0l4avjicbncbfjsuevjm572muvbes@4ax.com>,
John Fields <jfields@austininstruments.com> wrote:

[...]

much room you've got,

I've certainly got the size of the PTC. The height is limitted to about
0.4 inches. The width do about 1.3. The length is less constrained.
Smaller however is better.

how much you can afford to spend for a solution,
Cost is almost no object. If it adds $30 to the component cost no-one

will even question it. Up to maybe $100 could still fly.

how much overvoltage you can stand

I have a logic line that goes 0 to 5V. I need to turn that into a +/-12V
swing at up to 0.25A. Ideally the device that converts to +/-12 also is
self protecting up to 600V. My current thinking is to use 600V MOSFETs to
drive the line and turn them off if bad things happen.

and what the high voltage sources look like.

The 440VAC is a high powered mains service. For short times it can
produce nearly infinite current much like a wall outlet while you wait for
the fuse to blow. The 440V may be fused at 100A.

The DC is the output of a high voltage supply that has a large filter
capacitor at its output terminals. I think its a 2200uF low ESR component
in most cases. The DC makes it hard to wait for a zero crossing to
interrupt as one could do with the AC line.

I guess I _could_ email you something as well as post it to abse for
whoever else is interested if you'd care to describe your requirements
and your equipment in greater detail.

Yes an e-mail would be very helpful. My e-mail address is not
antispammed.

--
--
kensmith@rahul.net forging knowledge

 

[Adrian Jansen]

Andy wrote:

Hi,

I designd a dataloggor which need to give me temprature en presure. I
used an atmel 8051 microcontroller to control the sensors and sending
the data to pc or storing it on chip memory.

The temprature is dedected with a maxim ic, which is using 1 - wire
protocol to communicate. I know there is a IC that translate UART
(RS232) to 1 - wire. But I'm already using my one an only UART to
communicate with the PC.
So the only solution is to write my own 1 - wire protocol.

Does somebody have a easy to understand application note. Or more
detailed: the bitrate, how to code the date, etc.

thanks,Andy
Have a look around the app notes on www.mcselec.com He has lots of good

stuff on AVR interfacing with various devices, 1 wire included.


--
Regards,

Adrian Jansen adrianjansen at internode dot on dot net
Design Engineer J & K Micro Systems
Microcomputer solutions for industrial control
Note reply address is invalid, convert address above to machine form.

 

[Joerg]

Hi Mike,

This version seems somewhat more likely that the oft-reported but
unsupported claim that they stand for Jack Kilby.


Could very well be. John Kardash is often mentioned as the inventor of

the JK flip-flop. I think he is still on the Taracom management team. So
we could ask him ;-)

Regards, Joerg

http://www.analogconsultants.com

 

[John S. Dyson]

In article <ck3d5e0ckh@drn.newsguy.com>,
Winfield Hill <Winfield_member@newsguy.com> writes:

John S. Dyson wrote...

(Hint: it is okay to be for/against a candidate, but when hatred and
other kinds of semi-sanity start being exposed, then the Dems and
their supporters like Bloggs and Win start exposing their relative
amounts of (in)sanity. Frankly, psychiatrists who are starting their
practices should take a look at Dems posting on the various groups as
potential patient referrals.)

You can take you Hint and shove it up your ass.

Thank you for showing a perfect example of the hatred that shows the

immature personality problem. Very good -- at least I hope that you
are just showing an example of the leftist hatred and mental illness
issue. .

John

 

[John S. Dyson]

In article <Q43RICMvWZZBFwmB@jmwa.demon.co.uk>,
John Woodgate <jmw@jmwa.demon.contraspam.yuk> writes:

I read in sci.electronics.design that John S. Dyson <toor@iquest.net
wrote (in <ck3eut$okr$3@news.iquest.net&gt about 'The Rational Mind of
Fred Bloggs', on Thu, 7 Oct 2004:
Hatred is
problematic.

No, it's not 'problematic'. That's 'touchy-feely' woolly-mindedness.
Hatred is a manifestation of evil, and the simplest way to explain what
the concept of 'evil' is.

Perhaps I was understating the problem from the Bush haters. Even

being 'soft' in the description of that hate-illness results in insane
responses from the leftist hate-filled creatures.

John

 

[Winfield Hill]

Ken Smith wrote...

I think it is that I have to hold the current below lets say 3A
while the device trips and then the voltage can rise to 600V.

The PTC fuses would be nearly useless and the "600V" rating
meaningless if that were true. I am trying to order some of
these beasts to satisfy my curiosity with some bench tests
to find out for sure.


--
Thanks,
- Win

(email: use hill_at_rowland-dotties-org for now)