Driver to drive?

[John Popelish]

w_tom wrote:
(snip)

Every solution requires that earth ground.

Every solution to his specific problem.
But to make a general statement, I think there is an exception.
A metallic enclosed system, with no signals related to Earth potential
is quite immune to lightning. Even electronics inside an automobile
can sometimes stand quite a strike (depending on the electrical
continuity of the body).

--
John Popelish

 

[Eric Griswold]

I use a mercury vapor lamp (sort of lke a streetlight) connected to a simple
timer. The lamp takes about 5-10 minutes to come to full brightness, and
also, it starts out very 'pink' just like real dawn. And it end up hella
bright just like real sunlight.

--eric


"John Popelish" <jpopelish@rica.net> wrote in message
news:41BB81C4.8E3692E1@rica.net...

fredrik_aldrig@hotmail.com wrote:

I intend to build a simple dawn simulator for my wife. She likes the
idea of waking up to the increased brightness of the bedside lamp
rather then the alarm clock noise, and that sounds good to me

 

[John Woodgate]

I read in sci.electronics.design that Allan Herriman <allan.herriman.hat
es.spam@ctam.com.au.invalid> wrote (in <057qr09dbrcu8pv89utpqadfbigchnco
bq@4ax.com&gt about 'Basic questions about microphones and mic preamp
design...', on Mon, 13 Dec 2004:

There are standards that defined the electrical characteristics of the
"P48" interface: IEC 268-15, EN 61938, etc.

IEC 268-15 (aka 60268-15) was replaced by IEC 61938, and EN 61938 is a
clone of that.
--
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

 

[Ken Taylor]

"John Popelish" <jpopelish@rica.net> wrote in message
news:41BD3354.7A9109CF@rica.net...

w_tom wrote:
(snip)

Every solution requires that earth ground.

Every solution to his specific problem.
But to make a general statement, I think there is an exception.
A metallic enclosed system, with no signals related to Earth potential
is quite immune to lightning. Even electronics inside an automobile
can sometimes stand quite a strike (depending on the electrical
continuity of the body).

--
John Popelish

I note: "is quite immune to lightning" and "can *sometimes* stand quite a
strike".
Ergo an isolated system is *not* immune.

Ken

 

[ILYA]

At least in Europe, most telephone exchanges use a negative voltage
referenced to good old mother Earth.
Why negative? Is it some 'cathodic protection' in case a pinhole leak
occurred?

For > 99.9% of the time, my phone is on-hook, so one of the wires is
at -48V (actually it's about -52V) and the other is within 1V of
earth.

Some lands use another voltage levels...
For analogous local telephone network in my city:
not hold 60V
hold 6..15V
ring ... up to 200V! (be careful!)
pair cable.

 

[martin griffith]

On Mon, 13 Dec 2004 08:28:59 GMT, in sci.electronics.design Robert
Baer <robertbaer@earthlink.net> wrote:

Allan Herriman wrote:
snip
WHAT DO YOU MEAN, THE MICROPHONE IS PUTTING OUT HALF A VOLT?

Regards,
Allan

snip
Any "micropnone" that has an audio output signal of 500mV already has,
by definition, an amplifier stage built in, and that level is
essentially LINE LEVEL.
well, you can get up to 0dBu out of a microphone,

http://www.gprime.com/proaudio/tubes/tubes.htm




martin

Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.

 

[Quack]

Thankyou everyone for your suggestions.
A lot of useful info in there .

It has been decided to use a standard PC case in the existing machines,
hopefully this will sort it out.
Also we will make a much better attempt at grounding things.

For the future, the enclosures will be made with metalic frames (well
grounded) and _REAL_ embedded boards will be used, no more cheap pc crap .

The motherboard changes already would have covered the extra cost for using
good quality embedded boards. Oh well. Live and learn .

Regarding comments about humidity and anti-static carpet spray's, for
obviouse reasons the environment can not be under our direct control all the
time, so whatever we do has to be pretty tough. Other machines seem to
handle it fine.


Thanks again

Alex.

 

[Winfield Hill]

martin griffith wrote...

Robert Baer wrote:

Allan Herriman wrote:
WHAT DO YOU MEAN, THE MICROPHONE IS PUTTING OUT HALF A VOLT?

Any "micropnone" that has an audio output signal of 500mV already
has, by definition, an amplifier stage built in, and that level
is essentially LINE LEVEL.

well, you can get up to 0dBu out of a microphone,
http://www.gprime.com/proaudio/tubes/tubes.htm

"... peak readings of 1 volt or more were common, especially
from close up microphones on voice and drums." Nice ref.

Speaking of tube vs transistor sound under overload, what's a
good comprehensive article that's newer than that 1973 tome?


--
Thanks,
- Win

 

[Phil Hobbs]

Tara wrote:

Based on some requested info from respondants, here is more about the
proposed Crystal Oscillator book.

The book will introduce the basic concepts of crystal oscillator
theory, describe their operation, and explore their various
applications. Special attention will be given to environmental and
operational parameters (such as keeping the crystal inside a
temperature-controlled "oven" for increased frequency stability).
In addition, there will be material on the use of crystal-controlled
oscillators in embedded systems.
snip

The major thing that appears to be missing is automatic level control. It
really isn't possible to make a crystal oscillator with good close-in phase
noise performance without using ALC. It seems an odd omission--nowadays
there is little other reason for building our own oscillators.

Cheers,

Phil Hobbs

 

[Anthony C Smith]

"Jaye Gallagher" <msjaye@removethis.msjaye.com> wrote in message
news:41bcf579$0$3603$61c65585@un-2park-reader-02.sydney.pipenetworks.com.au...

Try this link- http://sound.westhost.com/projects-8a.htm
Elliot has many other links to designs on the site including limiters etc,
all of which are low cost
He also has good answers to the questions you asked.
Regards
Anthony

 

[Mark Jones]

Rich Grise wrote:

Anybody ever heard of anything like this? It sounds pretty cool, if it's
not just pie-in-the-sky.

Hmmm... a Russian, a Frenchman, and a Chinese walk into a bar in
Arkansas...

 

[panos v]

Hi

Thanks for your answer.
You say that you measured the frequency for Vcc=5V & Vcc=15V and you
found it different by 5KHz?
So the same "problem" (if it is one) appears to you to. About the caps,
they were indeed of various types. Also what is "culprit"?

panagiotis




On Sat, 11 Dec 2004 11:23:12 +0000, Terry Pinnell
<terrypinDELETE@THESEdial.pipex.com> wrote:

panos v <2222@yahoo.gr> wrote:

I have a question concerning the function of the 555 oscillator in
astable mode.
In particular the external elements i have connected to the 555 are
those depicted at the
datasheets of all the 555 ics (LM555, NE555 etc). The 2 resistors are
above 1K Ohm (Ra=1K & Rb=6.8K),
the C capacitor's value is greater than 0,0005uF (C=0,001uF) whereas a
0,1uF capacitor is connected
between the "Control Voltage" pin and the ground.
The above connection with the aforementioned values for the external
elements adjust the 555 so that
it theoretically produces a frequency of 98KHz, more or less. The
problems lies in the fact that the
experimental frequency, produced by the ic, is lower than the
theoretical by around 30KHz.
The discrepancy of theoretical and experimental value appears also in
other "valid-practical" values of
Ra,Rb & C with different deviations. I have also tried the LinCMOS
version of 555 (TLC555) with the same results.
Another odd phenomenon, equally unwanted with previous one, is the
shifting of the produced frequency whenever
the value of power supply of the 555 is changed, always ofcourse within
the allowed limits (4.5->16Volts).
The datasheets of the various 555 mention clearly that the HIGH and LOW
times, and hence the frequency, are
independent of the power supply.


Any help is wanted

Very odd. If you hadn't explicitly said above that you'd got the same
problem even after changing the capacitor, I'd have guessed that was
the culprit. Simulating, I get F(Vcc=15V) = 95.7kHz; F(Vcc=5V) =
90.6kHz. Were your caps of different types too? Maybe a bad batch..,

 

[James Sweet]

At a few places I worked over the years, the design engineers
would roughly calculate or make an educated guess about the
resistor value and reach in the parts bin and solder tack on a
resistor.... and then change it if need be. I have seen them
also use a potentiometer to zero in on a critical value....

If you haven't seen engineers, technicians, and servicepeople
using resistor/caoacitor substitution boxes, your experience
must be quite limited. They are commonly-used tools.

I can see where a capacitor sub box would be useful, but for resistors it
really makes more sense to have a few pots with clipleads. Either way, if
people are buying the thing then keep making them, there's plenty of vastly
less useful stuff on the market.

 

[Bob Stephens]

On Mon, 13 Dec 2004 12:08:50 -0700, Don Lancaster wrote:

Simulation has almost completely eliminated the need for substitution
boxes.
Many decades ago.

Intentional pun???


Bob

 

[Ken Smith]

In article <41BD1B55.DFC8207C@rica.net>,
John Popelish <jpopelish@rica.net> wrote:
[...]

If the wire gets hot enough to vaporize copper but not Iron, It is
going to set the house on fire, anyway.

Many a wooden barn has survived a lightning strike like that. You have to
press something bright red hot to a hunk of wood for a fair time to get a
self sustaining fire going. If its raining and the wood it wet it takes
even longer.

Lightning often hits trees and wooden structures, causes parts of them to
explode and yet does not lead to a self sustaining fire.

I googled about on the subject and could only find one reference for the
type of wire and that said "copper".



--
--
kensmith@rahul.net forging knowledge

 

[Clarence]

"Bob Stephens" <stephensyomamadigital@earthlink.net> wrote in message
news:d3fowgjn0xiz$.x5i9omsx6a5w$.dlg@40tude.net...

On Mon, 13 Dec 2004 12:08:50 -0700, Don Lancaster wrote:

Simulation has almost completely eliminated the need for substitution
boxes.
Many decades ago.

Intentional pun???

Bob

Don is Always deliberate!

 

[Don Lancaster]

Clarence wrote:

"Bob Stephens" <stephensyomamadigital@earthlink.net> wrote in message
news:d3fowgjn0xiz$.x5i9omsx6a5w$.dlg@40tude.net...
On Mon, 13 Dec 2004 12:08:50 -0700, Don Lancaster wrote:

Simulation has almost completely eliminated the need for substitution
boxes.
Many decades ago.

Intentional pun???

Bob

Don is Always deliberate!

what those French Veternarians call a four paw.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[John Larkin]

On Mon, 13 Dec 2004 22:30:17 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Hi Jim,

I have trouble eating "on the road".

I often opt for a bottle of wine and a can of cashews ;-)



Wine is supposedly good for the heart and vascular system. But cashews?
Maybe you could buy an old ADR scanner and check your carotids and other
vessels regularly...

On biz trips I try to find a good old brewpub with American cooking.
Even a burger can be a delicacy if it is done properly. It's just that
most people don't know how to do that anymore.

If you get up to SF, the best burger is at the Bull's Head in the West
Portal neighborhood. No draft beer, though.

John

 

[Jon Elson]

Rich Grise wrote:

Anybody ever heard of anything like this? It sounds pretty cool, if it's
not just pie-in-the-sky.



They found to their surprise that the dipoles in nanomaterials form a new
state when the temperature is lowered.

Ah, the "temperature is lowered". Hmm, how FAR is it lowered? To 4 K,

maybe?
Not too practical for your next laptop.

Jon

 

[John Larkin]

On Mon, 13 Dec 2004 02:16:23 GMT, Rich Grise <rich@example.net> wrote:

Anybody ever heard of anything like this? It sounds pretty cool, if it's
not just pie-in-the-sky.

All this nanotech stuff is like that. Every time somebody discovers an
obscure effect, they seem obliged to say that it will lead to a cure
for cancer or flying cars or something. Never does.

John