Scientific and Technical Subjects
- The Knowledge index
- Classical Mechanics
- How a delta sigma codec works
- The American National Software Failure
- Connecting W98 & W3.11 with an
Ethernet
- The Effect of Electric
Current on
Human
Flesh
- The Difficulty of Space Travel
- The Coming Monsters
- Lock-In Amplifiers
1. The Knowledge Index
It is time to end search engines and organize knowledge in a tree so
that
wrong result will not be an issue. Here is one small branch:
Physics
Electrostatics
Sensors
Using the field effect transistor to detect electric
fields
The electric field from a piece of plastic rubbed on hair is easily
detected at a range of one foot. Objects like charged sweaters can be
detected
at a range of ten feet. The electric field due to the power line is
apparent
both inside and outside the house. On a clear day the electric field in
the atmosphere can be readily detected.
Astrodynamics
Orbital dynamics/orbital equations
Programs for propagating orbits and satellite tracking.
See my orbit programs
Low Temperature
Superconductors
See my
file on Superconductors.
2. Classical mechanics
There is no knowledge more important than classical mechanics. You
might
as well just go learn Newton's laws. Folks used to say that if you knew
Newton's laws and all the boundary and initial conditions then you
would
know all the past and future of the entire universe. This is still a
good
approximation. Learn why.
3. How a Delta Sigma CODEC Works.
The delta sigma codec has two parts. The front end is a delta modulator
which is understandable to analog folks. The back end is a decimator.
Its
job is mathematical and it doesn't matter what you use to do it. I
model
the delta modulator as a comparator possibly followed by an integrator
and then a D type flip-flop. The output of the flip-flop is the output
of the circuit but it is fed back to a digital integrator of sorts. One
way to model the digital integrator is as a up-down counter followed
feeding
a D/A. If the D flop Q output is considered to be a count up signal
when
it is a 1 and count down when it is a 0, then every clock causes the
counter
to either count up one or count down one. The output of the D/A goes to
the other input to the comparator. I suppose when power is first turned
on, the counter is sitting at 0 which makes the D/A put out the lowest
voltage possible - the bottom rail. The signal ought to start off doing
nothing which corresponds to a DC at half the power supply voltage,
assuming
there is only one supply. Then the comparator will put out a string of
ones which pass through the flop and cause the counter to count up. The
D/A output will ramp up and catch up with the input signal. All this
time
the D flop is putting out a bunch of ones. Finally the D/A passes up
the
input and the comparator switches to a zero which makes the counter
count
down one count. Thereafter the system hunts, jumping up and down one
bit
and putting out a string of alternating zeroes and ones. Now if the
input
tries to ramp up or down, as when an audio signal is present, then the
system will follow it. As that happens the ones and zeroes will no
longer
be equal. A couple of extra ones means the voltage is rising and a few
extra zeros means the voltage is falling. All is well as long as the
input
does not rise too fast. That is not likely though since the sample rate
exceeds one megahertz. Also the counter and D/A is actually only a
little
capacitor and a big capacitor. The little capacitor takes a charge from
the plus rail if it sees a one and a charge from the minus rail if it
sees
a zero. So this thing is putting out ones and zeros at a tremendous
rate,
little messages that say go up a hair or go down a hair. That is all
that
is necessary. To convert all the previous gibberish into nice binary
count
style sixteen bit words is the job of the decimator. The simplest
decimator
is just an adder. If you count 256 bits you get up to FF. So count the
delta modulator output bit stream for 256 clock pulses. You will get a
number somewhere between 0 and FF. This is the output of the Decimator.
If the delta modulator is DC you will get 80 HEX. If the audio is a
high
frequency and large amplitude you will get a large number, like FE or
01.
0 and FF are the digital equivalent of banging against the rails, so
adjust
your gain accordingly. Now in the real world the things are much more
complicated
than this. Some delta modulators change their step size if they can't
keep
up. I don't know how they tell the decimator but it doesn't sound hard.
Also the decimators have lots more bits than they need, so they do all
kinds of averaging to use the extra bits before throwing them
out.
4. The American National Software
Failure
There is a saying that if you were not there looking over the shoulder
of the guy who wrote the software then you will never be able to
operate
it satisfactorily. This is testimony to the user unfriendly software
and
manuals. Personal computers are impenetrable and harsh. Each new
piece of hardware and software just made the mess worse.
Commands Missing from DOS
1. Tree Compare - This is like FC but compares all files in two
directories
and all the sub directories included.
2. Find Duplicates - There may be duplicate files scattered around
on
my hard drive. I don't know the names - just find them.
3. Tree size - Notice how Windows Explorer (was File Manager) does
not reveal how much
space
is used in a folder and all included sub directories as a single
number.
Well how about "Myfolder contains 23 MB."
4. A real file finder that finds "all files of type txt containing
the
words 'software history' but not the words 'for sale' made between the
dates 6-10-98 23:50 and 6-11-98 01:15."
Other Problems with Microsoft Software
The Windows Explorer like the original File Manager copied the DOS DIR
command and none of them list the size of directories. Why the business
community allows this failure is beyond me.
The new Microsoft Internet Explorer has a unique address book format
called FAVORITES. The new FAVORITES is not compatible with the old
FAVORITES
and of course it cannot use Netscape BOOKMARKS files. On the other hand
the new Netscape BOOKMARKS can read the old BOOKMARKS and the old
FAVORITES
and possibly other files as well using an automatic interpreter called
IMPORT. Explorer does not have IMPORT.
Outline for writing code correctly
Good programs are mostly comments. Comments should explain why a
program
is being written, who it is for, what equipment it runs in, what each
line
does, what the interfaces are, what the interfacing equipment is, maybe
even how it works, and finally who wrote it and the date of each
change.
Remember one time I wrote detailed instructions which were sufficient
for
a novice and perfect stranger. A year later I found out who that
stranger
was. It was me, and every detail was criticized for lacking
justification.
Outline for writing the manual correctly
A software manual must define the operating environment for the
software.
It must describe how the equipment is prepared to run the software. It
must describe how to start the software and how to stop it once
started.
Ninety percent of all programming effort is identifying the
interfaces
and the requirements. Learning and writing code is the easy part.
4. Coax Ethernet for Windows 98
to Windows
3.11
Coax was chosen because it is both cheap and well understood. Don't
forget
the 50 ohm anti reflection terminations at each end.
a. Network setup for the Celeron 333 using Windows 98
Go to Start, Settings, Control Panel, Network.
Click on Client for Microsoft Networks. Press Add, Service.
Select File and printer sharing for Microsoft networks.
Allow it to read the CD and restart.
Go to Start, Settings, Control Panel, Network.
Under the Configuration tab highlight Client for Microsoft Networks
and press Properties.
In the properties window "Logon validation" avoid the logon square.
It is for networks with servers. Put in the work group name. I used
workgroup.
In the box below "Network Logon Options" choose "Logon and Restore
Network
Connections."
Go to Start, Settings, Control Panel, Network.
Under the Configuration tab highlight
File and printer sharing for Microsoft networks. Press
Properties and Verify that Browse Master is Automatic.
Close out the Control Panel.
Open the desktop Network Neighborhood and verify that the
other computers in the network are there.
In Windows Explorer highlight the C drive and pull down
Files, Sharing. Do not use the drive letter as the name or
the other computer operator may get confused about whose
drive is whose. Access type is Full for me and Passwords
is left blank.
b. Setting up the '486 Using Windows 3.1.1
Only famous name like 3-Com cards can install and they must use the
windows disk 7 and 8 drivers. Hardware supplied drivers and 3-Com's
internet downloadable drivers do not work.
The I/O address was 300 and ROM memory DC00 and interrupt 5 for both
486 3-Com cards.
Method for connecting 3-Com Ethernet cards.
These cards are connected by coax cable and require 50 ohm
termination. There is no hub, server or anything between the machines.
Configure and test the cards using 3c503.exe. This 3-Com program does
complete diagnostics for the card and network.
Configure I/O address 300, ROM address DC00, Interrupt 5 using the
diagnostic tests. 1. Internal, 2. Adapter, 3. Echo. For Echo,
configure the card on the other computer using Echo server setup.
Under Windows Networking choose Install Microsoft Windows Network.
Turn on the sharing. Under adapters choose 3-Com Etherlink II or
IITP 8 or 16 bit NDIS2 compatible.
For protocol choose IPX/SPX transport with NETBIOS
and Microsoft NetBEUI.
Set Base I/O port 0x300, ROM address DC00, Interrupt 5 and
location onboard. User name will become the login user, and
work group was workgroup, Computer name can be anything since it is
not used.
Add:
To Autoexec.bat: C:\windows\net start
To Config.sys: DEVICE=ETH503.sys /I:5
When restarting it says Windows has modified your Config.sys
system.ini, and protocol.ini, and put the old ones as .000.
In Main\Control Panel\Network choose a computer name and a
work group name, if this was not done above.
The computer name must be different for each computer while the
work group name must be the same.
In File Manager to share hard drives under Disk choose Share as.
Pick a proper name which is not a drive letter so you won't get
mixed up with the hard drive on the other computer.
Then go to the other computer and choose Connect network drive
in the same menu.
Because I had used interlnk and intersvr to serial link the other
machine and had already two floppies and two hard drives, I got up
to drive h!
The other machine had a parallel zip and got up to g.
For printing Print Manager has to be running and open.
Maybe the sharing has to be reselected while Print Manager
is open. A list of printers shows up on the machine with
the printer.
5. The Effect of Electric Current on
Human
Flesh
a. Disclaimer
Don't blame me if you fry yourself. I did these experiments already and
they never need to be done again. Just take my word for it. Most folks
even electronic engineers have a weak understanding of what it takes to
get shocked. So here it is.
b. Getting the current
Most folks believe that high voltage is the thing to be afraid of.
Other
folks believe that high current is the thing to fear. I got the inside
story when I was a kid. For those who believe in causality (cause and
effect),
I used to believe that voltage causes current. That idea comes natural
considering the hydraulic analogy. Doesn't pressure cause flow? Well if
voltage is like pressure and current is like flow, then I am right.
Well
some scientists just say voltage and current are "associated" with each
other. Any way I claim that you need voltage ACROSS YOU to get current
THROUGH YOU. It doesn't do a bit of good (assuming you are trying to
get
fried) to grab a million volt (DC) wire, if you are otherwise
insulated.
You will just sit there and FLOAT at the wire's potential.
There is a similar story for current. All the current in the world
will
not hurt you if it is going through someone else. Touching a big old
bus
bar that is carrying a lot of current at low voltage will not hurt you.
c. Feeling the current
To feel it you have to make the current flow through you. That usually
means two connections. Before you even try to get connected, lets talk
about impedance. Devices that can produce high voltage but only tiny
currents
are called high impedance. Static electricity is like that. You can get
up out of a chair and get charged up to ten thousand volts. Walk over
to
a grounded pipe and touch it. If you can see the spark it is something
like five thousand volts. If you feel it, that is more like ten
thousand
volts. If it hurts that is more like thirty thousand volts. Notice you
didn't feel the ten thousand volts on you while you carried it across
the
room. I have a 750 volt power supply that has such a high impedance
that
I can touch across it and not even feel a thing.
Now if the high voltage source is low impedance look out. I heard about
a squirrel that got connected across the terminals of a 13kv
transformer.
There was a loud bang and a white flash. Little black pieces of the
squirrel
came raining down.
Then there are low impedance devices. These devices can produce a
large
current but have only very small voltages. A battery powered flashlight
is almost a low impedance device. Try holding a metal flashlight while
it is on. You will not feel anything even though there is a current
through
the metal that you are touching. There is even a voltage across it end
to end. You can touch both ends and not feel anything, but there is a
tiny
current through you.
If you find a low voltage high impedance source of electricity, that
is a pretty weak signal. You will probably need amplifiers to detect
it.
I had a debate about low voltage high current sources one time at
the
University of New Orleans. Harry told me that a device that can give a
high current even at a low voltage would be dangerous. So I brought in
a bank of a dozen capacitors totaling 20,000 microfarads, connected by
two big old bus bars a half inch apart and not insulated. I asked him
if
my toy was dangerous. He said it should definitely shock me. So we went
back into a physics lab and connected up a DC power supply and a
voltmeter.
It had a current meter so we could watch the capacitors charge.
I turned it on, brought the capacitors up to 12v, and asked "Will I
feel that?" He said yes, so I touched both bus bars. I felt nothing. My
hands were dry.
I brought the voltage up to 20v. "Will that shock me?" "Yes" I
touched
again and felt nothing.
I increased the voltage to 30v. "Will that shock me?" "Yes" I
touched
again and felt nothing.
I increased the voltage to 50v. "Will that shock me?" "Yes, That
should
be a horrible shock. Look out!" I put my hand flat on the bus bars and
felt nothing. "Are you satisfied now that I am right?" He was still not
certain.
I decreased the voltage of the power supply by turning the knob.
Suddenly
the voltmeter went to zero. The capacitors had discharged through a
sneak
circuit in the power supply. I played with the knob. The power supply
was
dead. A transistor had been blown away-shorted. I was in trouble. We
got
a schematic and figured out how this Disaster had happened. I offered
to
fix it but the old guy who ran the shop just wanted us to go away. I
have
much bigger capacitors now, totaling a half a Farad, and I am scared of
shorting them. I keep them charged anyway. It is good for electrolytic
capacitors
One time I made measurements to find out what current feels like. I
connected a milliammeter in series with one hand and used the other to
adjust the voltage of a DC power supply.
I found out that I could not feel currents below 0.1 ma. This fact
is
used by the familiar touch lamps that turn on and off when you touch
them.
The current is just too small to feel.
At about one ma I started to feel something. It didn't really hurt,
but it was definitely detectable.
At five milliamperes the current hurt, and at ten ma it hurt so bad
I couldn't stand it any more. I figure 100 ma would do real damage. I
heard
that shock treatment uses hundreds of ma and that scares me.
Now to change to voltage. I never measured the current but for DC,
with
dry fingers, I start to feel it somewhere between 70 and 90v. At 100v
it
is getting bad, and 105 is all I can stand. The strangest feeling
though
is that only one finger hurt when the current was steady. Then when I
pulled
my hand away and free, the other finger suddenly hurt instead for a few
seconds. DC is strange. For AC lower voltages can be felt.
I once saw a government chart of pain or damage vs frequency. It was
remarked by a buddy that 60 Hz (the standard AC power frequency) was
the
most dangerous frequency that could be found.
In my time I have had my share of accidents. Once a tube circuit
power
transformer shorted out while I was connected between the earth ground
and chassis ground. I later measured 350 VAC. The current was from one
finger on one hand to another finger on the other hand. It was so bad
that
I could not move either arm to get away. On my left hand the metal
probe
was actually making a small hole in my skin about 2 mm diameter. I saw
the hole growing and for a second could do nothing. Finally, I stood up
and pulled away breaking the circuit. I have since noticed that the
outermost
millimeter of skin accounts for the majority of the resistance measured
by a voltmeter. Once an injury has broken the skin the current may
increase
markedly.
Another time I had a 2 microfarad capacitor charged to 1000V just
laying
around. I was looking for something and my chin touched a wire sticking
up. The other contact was a hand. The effect was instant. I saw a flash
of light like the A bomb went off. I felt like someone hit me with a
bat
on the back of the neck. It was all over before I could even think of
moving.
Some years later I was doing an RF experiment with 10 watts at 146
MHZ
from a transmitter. The capacitor was held between two fingers with the
power applied and it was arcing to one finger. I could smell my flesh
burning
for some time but deliberately would not let go in order to finish the
experiment, which took 15 seconds. Afterward there was no visible mark
and I concluded that the injury was much less significant than a
mosquito
bite. If you want to smell your own flesh burning just rub your hands
together
until they get warm and quickly sniff the hot surface. Another way is
to
put your hand directly over a camera flash strobe that is battery
powered.
(Not the kind with the burning bulbs. That will "fry" you.) Immediately
after the flash, smell your hand.
Many years later I was a little safer, working with only one hand.
My
hand got connected across a similar capacitor. It was a light touch and
a tiny piece of flesh exploded into a ball of yellow fire. The ball was
about an inch in diameter. Afterward there was a visible mark on my
skin
about 0.5 mm diameter. So the color of exploding human flesh is orange
from the sodium in it.
5. The Difficulty of Space Travel
Most folks don't realize how tough a place space is to live in. That
includes
the Moon and planets. The South Pole is a piece of cake in comparison.
In space you have to carry your own air, water, and food. We still do
not
know how to recycle these things enough to make a difference. Space is
full of radiation. If you stay there long enough you will be well
cooked.
Shielding is too expensive. At least at the South Pole you can go
outside
and breathe the air and pull off your gloves and feel your house. Try
that
in space. Then there is the propulsion. If your engine fails you won't
even come back in pieces. I would rather be in a plane whose engine
failed,
than a rocket that lost 10% of its thrust. If you want to shoot for the
stars you are really crazy. Any conceivable propulsion system will take
millions of years to get there, and by then even the bugs that ate you
after you died will be long dead. The electronics will be ruined by the
radiation, and the fuel tanks shot full of holes by grains of sand that
you happened by. But the worst thing is that if you are moving with any
reasonable speed relative to your local space junk, and it might not be
your fault, any small object that hits you, say a BB, will hit with the
force of a stick of dynamite. A direct hit by a bowling ball sized
object
will act like a nuke. So forget it. Little green men will have similar
problems so they will never come here.
6. The Coming Monsters
Folks in the United States think America was chosen by god to be
eternal.
Better study your history again. Not even an animal can claim that
destiny.
The hard school of evolution is not going to go away just for your
funny
ideas. Change is permanent. And to make things even worse there are
folks
like me who are fooling with genes, cloning all sorts of evil things.
Someday
we are going to start modifying human genes and people will never be
the
same again. If you want to face it squarely just remember the
scientific
rule from quantum mechanics- "If it can happen it will happen."
Humanity
cannot withstand this forever. The result of drastic meddling, can only
be called MONSTERS. They will be here before you know it and they will
inherit the Earth.
7. Lock-In Amplifiers
The lock in amplifier, sometimes called a boxcar averager, is an
amazing
device. It uses a phase sensitive detector to pull a constant frequency
AC signal out of noise. Because the bandwidth can be made very small,
it
can detect very tiny signals. The downside of this of course that you
have
to wait a long time to get the result - usually a yes /no decision
about
the presence of the signal.
.
A number of people have contributed articles and leads. If you
send useful material I may add it. My email address is on the top page.
Filename: Technolo.htm Last modified:
September 2004