Chip with simple program for Toy

[Robert Monsen]

Try looking into CPLD or FPGA logic. You can do pretty cool things with
them.

Regards

"Dan Fraser" <dmfraser@sbcglobal.net> wrote in message
news:3F18EE4F.687CA3CA@sbcglobal.net...

About 2 transistors per square cm. Its called a printed circuit board.

Even an old LSI like an 8088 processor with 29,000 transistors requires
a plant with a $50,000,000 price tag. A Pentium 4 factory costs
$2,000,000,000

However, there are silicon foundries in Taiwan who will make a custom
VLSI for you. The first one may be as cheap as $100,000. Each one after
will be about $1.00.


--
Dan Fraser

From Costa Mesa in sunny California
949-631-7535 Cell 714-420-7535

Check out my electronic schematics site at:
http://www.schematicsforfree.com
If you are into cars check out www.roadsters.com

 

[Ratch]

"buck rojerz" <inorbit@outerspace.org> wrote in message
news:Xns93C035EA0A020ou812@216.168.3.44...

After following this 'wild' thread, it seems as though the main argument
revolves around this "Ohmic" and "non-ohmic" thing. Can any one of you
tell this old technician, just what "non-ohmic" is?

Without knowing what your explination is, one might assume non-ohmic as
being a material with no resistance. If that is the case, the only non-
ohmic substance would be super-conductors, but somehow it sounds like
that's not what you are meaning.

So, please explain what "non-ohmic" means to you. For the life of me I
can't figure out what you mean. In thirty years, I have never heard the
term.

Sure. Read this short link that was posted by me earlier. You will
find it enlightening. Ratch
http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc/Resistance.htm

 

[John Popelish]

jack wrote:

Hi,
I'm trying to find a schematic to build a small amplifier that will
take pulses with rise times of 1 to 3 ns and around 10 ns decay time
of only a few mV and amplify this up to 1 or 2 volts while not
loosing the rise/fall times. The pulses come from a photomultiplier
tube and maintaining the shape of the pulse is important. I'm not
interested in counting as yet,so I only need an amplifier. Does anyone
have any suggestions on how to approach this,or tips,or where I could
get schematics for this? Any help is appreciated. thanks jk

I would start with a current feedback opamp such as a CLC425:
http://cache.national.com/ds/CL/CLC425.pdf
with the photomultiplier anode going directly to the - input and the +
input grounded, with a resistor in parallel with a tiny capacitor, as
the feedback. You won't get 1 nanoseconds rise time but it will be
pretty fast.

--
John Popelish

 

[Lord Garth]

"Pfrogs" <Pfrogs@hotmail.com> wrote in message
news:3f1d698c$0$30576$a729d347@news.telepac.pt...

Hi,

I need a circuit that is able to do the following effect: 10 leds light up
sequentially (bar mode) when you turn the circuit on, staying on until you
switch it off, and when you switch it off the led turn off sequentially in
the reverse order that they where turned on.
Sometime ago, someone gave the following idea, which to me seems ok:
"Use the LM3914 bar graph chip- make sure its power supply pins are
supplied
from a large capacitor, isolated through a diode so that when the power
goes
off, the capacitor continues to power the chip for a few seconds. Wire
the
chip
in "bar" mode, not dot mode.
Next, place an electrolytic capacitor on its input terminal, and feed
the
terminal from a fairly high resistance (you may have to play with this
value)
that is connected to the power supply of the device you are powering.
The result is this- when power is applied, as the capacitor charges
up,
the
LEDs on the LM3914 outputs will form a sequentially illuminating bar.
This
will
stay lit as long as the device is powered. When power is removed, the
LM3914
will continue to run for a few seconds due to its "backup supply" made of
the
capacitor- note that the diode will prevent that capacitor from
discharging
through the rest of the circuitry, and make it specifically power the bar
graph.
As the capacitor at the input terminal discharges (and note that you
might
want a discharge resistor to set this rate of discharge), the LEDs drop
out
in
reverse order."
The problem is that I don't really know much about electronics, just some
basic circuits, so if anyone could help me here with the values for the
capacitators and resistances, I would be greattly appreciated. Even better
if I could get a schematic for such circuit.
I think that a good point for starting is the basic circuit schematic
(page
2) of the LM3914 data sheet (but I can't figure out the rest that I need
to
do to obtain the effect I want
The LEDs I'm using are bright blue leds, and I was thinking of using a
220V
AC/DC 12V 500mA transformer as power suplly.
Thanks in advance to anyone that could help me in any way.
Best regards,

Pfrogs

P.S: Does anyone know of a SPICE like software that has the LM3914 driver
on
the component library?

I'm assuming this circuit is for effect purposes only as it sounds rather
toy like. Consider an up / down counter and a 555 as a clock source.
Use the max / min outputs to halt the counter.

 

[Ratch]

"buck rojerz" <inorbit@outerspace.org> wrote in message
news:Xns93C035EA0A020ou812@216.168.3.44...

After following this 'wild' thread, it seems as though the main argument
revolves around this "Ohmic" and "non-ohmic" thing. Can any one of you
tell this old technician, just what "non-ohmic" is?

Without knowing what your explination is, one might assume non-ohmic as
being a material with no resistance. If that is the case, the only non-
ohmic substance would be super-conductors, but somehow it sounds like
that's not what you are meaning.

So, please explain what "non-ohmic" means to you. For the life of me I
can't figure out what you mean. In thirty years, I have never heard the
term.

Sure. Read this short link that was posted by me earlier. You will
find it enlightening. Ratch
http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc/Resistance.htm

buck

 

[Arthur Jernberg]

Problem is, whatever means you try to produce an electronic signal to jam
his reception makes you legally responsible for producing said signal. Since
you are doing it with a preumpetive reason to cause vendictely limit
another's ability to view public television he will have legal right to
charge you with an offence, let alone anyone else in the area that is
affected. It may be better to just discuss with him the situation and ask
to have the sound level reduced when watching his tele, that is unless you
have caused a situation already that will limit your ability to openly
converse with him. Cheers
"gothika" <gothika@earthlink.net> wrote in message
news:84vmhvcltn3e3apdd1lm959ie38ij9vnga@4ax.com...

I'm no expert but if he's watching something in the uhf/vhf band seems
what you need is a rf generator that can match frequency with what
ever channel he's watching then an amp to boost the signal to jam
strength and something to produce raster or even some really
irritating noise.(audio and video.)
If he pulling the signal through a vcr and using the rf out this makes
your task easier as all vcrs output the signal through channel 3 or 4.
(just buy a small rf modulator and a rf amp with enough guts to jam
the rf modulator in his vcr.
Some of the more technical savvy here can give you more precise
details.

On 15 Jun 2003 14:04:28 GMT, melaniegree64694@aol.com
(Melaniegree64694) wrote:

Hi
I have a neighbour who watches terrestrial television at a loud volume
into
the early hours. It's very annoying I have asked him to turn it down to
no
avail. Is there a simple jamming device I can make to turn his telly into
a
snowstorm and get good nights sleep? I have noticed that some vehicles if
they
have faulty electrics can produce this effect. Can I replicate this with
an
electric motor or such like?

Mel

 

[John Larkin]

On Thu, 24 Jul 2003 05:02:56 +0000 (UTC), "Randy "
<rgwg99@acsplus.com> wrote:

To those who may be interested,
I went back to the drawing board and came up with this:
The first step was to determine the Inductance of the primary.

L = 0.4 x 3.14 (120*120) 5000 x .003 / .750 x 10 E -08

This gave me a primary Inductance of 30 mh. I then solved for the Inductive
Reactance:

Is this your microwave transformer? This inductance seems awfully low.
Did you account for the core permeability, cross-section, and path
length?

X sub L = 2 x 3.14 x 60 x .030 = 11.3 ohms, applying Ohms law now will
yield,

120vrms / 11 ohms = 11 amps x 120 vac = 1.32KVA,

You're saying the tranny will pull 11 amps from the line with no load
on the secondary. Try it.

John

 

[Bill Bowden]

"Randy " <rgwg99@acsplus.com> wrote in message news:<01c35178$d6148420$252525d8@dialup>...

To those who may be interested,
I went back to the drawing board and came up with this:
The first step was to determine the Inductance of the primary.

L = 0.4 x 3.14 (120*120) 5000 x .003 / .750 x 10 E -08

This gave me a primary Inductance of 30 mh. I then solved for the Inductive
Reactance:

X sub L = 2 x 3.14 x 60 x .030 = 11.3 ohms, applying Ohms law now will
yield,

120vrms / 11 ohms = 11 amps x 120 vac = 1.32KVA,

almost double the power of standard M.O. transformers. The secondary is 660
mA @ 2000 volts.
I think this is what through me off initially. I saw that the secondary was
twice the size of common so, I thought wrong. This sec. is wound on a
bobbin and then wrapped, giving the appearance of size. When you
assume......................................

An Inquiring Mind
Randy Gross

Where did you come up with the formula for inductance of the primary?
The transformer should not draw 11 amps without a load. It should
be more like 1 amp or less. Why don't you measure it to find out what
it really draws? Just add a small resistor of 1 ohm (5 watt) in series
with the line and then measure the AC voltage across the resistor.
The current will be equal to the measured voltage, 1 volt = 1 amp,
2 volts = 2 amp, etc. From that you can calculate the inductance.

-Bill

 

[~^Johnny^~]

On Thu, 19 Jun 2003 10:05:16 -0400, A E <aeisenhut@videotron.ca>
wrote:

Alex wrote:

i am building a tesla coil and am wondering where the capicitaters go

Right next to the inducteraters.

But that's beside the points...
--
-john


~~~~~~~~
"The first step in intelligent tinkering is to
save all the parts." - Aldo Leopold
~~~~~~~~

 

[~^Johnny^~]

On Thu, 19 Jun 2003 12:31:20 -0600, "Bob Myers"
<nospamplease@addressinvalid.com> wrote:

Underneath the dilithium intermix chamber, connected in series
with the quantum isomorphic destabilizer and the Cavorite filters.
Note that you may need to rebalance the thiotimoline detectors
after installation, unless you're VERY careful with the transwarp
flux alignment.

And don't forget to discombobulate the fratostat, to prevent
neo-narcissistic corona discharge by unsupervised sproggen.
--
-john


~~~~~~~~
"The first step in intelligent tinkering is to
save all the parts." - Aldo Leopold
~~~~~~~~

 

[buck rojerz]

buck rojerz <inorbit@outerspace.org> wrote in news:Xns93C035EA0A020ou812@
216.168.3.44:

After following this 'wild' thread, it seems as though the main argument
revolves around this "Ohmic" and "non-ohmic" thing. Can any one of you
tell this old technician, just what "non-ohmic" is?

Without knowing what your explination is, one might assume non-ohmic as
being a material with no resistance. If that is the case, the only non-
ohmic substance would be super-conductors, but somehow it sounds like
that's not what you are meaning.

So, please explain what "non-ohmic" means to you. For the life of me I
can't figure out what you mean. In thirty years, I have never heard the
term.

buck

Man, did that ever bring this thread to a sudden stop.
What? Nobody knows?

 

[Tom Biasi]

Hi Roger,
You probably learned something making those diagrams, that's good but
personally I find them very difficult to read.
I would encourage students to use the calculator and be aware of what it is
they are calculating.
JMHO,
Tom

"Roger Johansson" <no-email@home.se> wrote in message
news:2cb1ivklfhtlk688uhgjo1ausopbodten9@4ax.com...

I have uploaded two electronics diagrams on the web.
Some readers may find them useful, and I would also like to hear
comments on the usefulness of such diagrams.

The first is a diagram with voltage horisontally, current vertically,
resistance diagonally, and power on the other diagonal.

http://www.ljusdal.net/~roger/VAOW2.jpg

This means that for a resistor in a circuit you can find the point
where the voltage and current meet, and see what the resistance and
the power is. Or start with any two values and get the other two.

This is faster than using a calculator, and you don't even need one
hand free, just fix your eyes on one point and see the scales you need
to read, Very handy at the workbench when your hands are occupied with
soldering iron and components.

I have had this diagram on the front of my homemade electronics
handbook for many years and used it millions of times.
It is a lot faster than using a calculator and the formulas
Volt=Amp*Ohm and Watt=Volt*Amp

I may also be more instructive to see it graphically, because one can
follow the lines and think things like, what happens if I raise the
voltage ten times, how much will the power increase, etc..

The other diagram shows the relations between inductance, capacitance,
frequency and impedance in a similar way.

It is useful to find the impedance of a certain component at a certain
frequency, or the resonance frequency of a LC circuit, etc..

http://www.ljusdal.net/~roger/LCFO2.jpg


Sorry for the technical quality. I have tried to create these diagrams
with computer graphics but gave up and scanned in my old hand-drawn
paper copies.

Are such diagrams available, with better quality, somewhere on the
web?

--
Roger J.

 

[John Larkin]

On Thu, 24 Jul 2003 20:26:19 +0000 (UTC), "Randy "
<rgwg99@acsplus.com> wrote:

John Larkin <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote in
article <fm30ivsd5d71lf8msdi2mie7vp4udplp91@4ax.com>...
: On Thu, 24 Jul 2003 05:02:56 +0000 (UTC), "Randy "
: <rgwg99@acsplus.com> wrote:
:
: >To those who may be interested,
: >I went back to the drawing board and came up with this:
: >The first step was to determine the Inductance of the primary.
:
: >L = 0.4 x 3.14 (120*120) 5000 x .003 / .750 x 10 E -08
:
: >This gave me a primary Inductance of 30 mh. I then solved for the
Inductive
: >Reactance:
:
:
: Is this your microwave transformer? This inductance seems awfully low.
: Did you account for the core permeability, cross-section, and path
: length?

Sounds like I'm about to go to school but, yes, I accounted for core
permeability: 5000 for soft Iron, the cross section is .003 sq. m and "l",
according to the text, is the length of the coil. Correct me if I'm wrong.
The only thing I did not account for is losses which, If I've been led
right, is about 2 to 3%.

I'm far too lazy to deconstruct your numbers back to the equation, but
I don't thing "length of the coil" makes sense. Length of the magnetic
path is relevant, and L goes inverse with this one.

Hey, hook it up to 120 and measure the primary current! It will likely
be bigger than theoretical, as most such trannies run a bit into the
core saturation region (less copper+iron = higher flux density = more
losses = cheaper transformer).

Magnetics are always a pain.

John

 

[Roger Johansson]

"Tom Biasi" <Tom@Home.net> wrote:

Hi Roger,
You probably learned something making those diagrams,

Well, I actually didn't make them myself, I have modified one of them
so much I could consider it at least partly hand-drawn, but the other
is from a component catalog some 20 years ago.

that's good but personally I find them very difficult to read.

I don't understand that. I find them much faster and easier to use
than any calculator, especially when I don't have my hands free.
The Volt-Amp-Ohm-Watt diagram is always on my workbench and I only
have to look at it to make calculations and adjustments to circuits I
am working on.

But maybe one needs to be accustomed to reading diagrams to have use
for it. I know such diagrams are much more in use in Germany than in
USA (the first diagram came from a german handbook originally, before
I modified it).

I would encourage students to use the calculator and be aware of what it is
they are calculating.
JMHO,
Tom

Okay, thanks for your comments.

I am surprised that I have not seen such diagrams on the many web
sites about electronics I have seen.
Maybe it is a difference of culture, if people don't learn to read and
use diagrams in school they will not find them easy to work with.

I would love to find some better versions of these diagrams and I have
searched, but couldn't find any on the web.
Maybe I didn't use the right terminology and search words.
If anybody knows what such a diagram would be called in english,
please tell me.

I have uploaded two electronics diagrams on the web.
Some readers may find them useful, and I would also like to hear
comments on the usefulness of such diagrams.

The first is a diagram with voltage horisontally, current vertically,
resistance diagonally, and power on the other diagonal.

http://www.ljusdal.net/~roger/VAOW2.jpg

This means that for a resistor in a circuit you can find the point
where the voltage and current meet, and see what the resistance and
the power is. Or start with any two values and get the other two.

This is faster than using a calculator, and you don't even need one
hand free, just fix your eyes on one point and see the scales you need
to read, Very handy at the workbench when your hands are occupied with
soldering iron and components.

I have had this diagram on the front of my homemade electronics
handbook for many years and used it millions of times.
It is a lot faster than using a calculator and the formulas
Volt=Amp*Ohm and Watt=Volt*Amp

I may also be more instructive to see it graphically, because one can
follow the lines and think things like, what happens if I raise the
voltage ten times, how much will the power increase, etc..

The other diagram shows the relations between inductance, capacitance,
frequency and impedance in a similar way.

It is useful to find the impedance of a certain component at a certain
frequency, or the resonance frequency of a LC circuit, etc..

http://www.ljusdal.net/~roger/LCFO2.jpg


Sorry for the technical quality. I have tried to create these diagrams
with computer graphics but gave up and scanned in my old hand-drawn
paper copies.

Are such diagrams available, with better quality, somewhere on the
web?

--
Roger J.

 

[Mark Fergerson]

Roger Johansson wrote:

I have uploaded two electronics diagrams on the web.
Some readers may find them useful, and I would also like to hear
comments on the usefulness of such diagrams.

The other diagram shows the relations between inductance, capacitance,
frequency and impedance in a similar way.

It is useful to find the impedance of a certain component at a certain
frequency, or the resonance frequency of a LC circuit, etc..

http://www.ljusdal.net/~roger/LCFO2.jpg

Looks like the one in the old ARRL handbook.

Mark L. Fergerson

 

[John Damm Sřrensen]

Roger,

Your "diagrams" are called nomograms. See
http://mathworld.wolfram.com/Nomogram.html
At least in the early 70's the design of these nomograms were taught to
electronic engineers in Denmark.
My brother in law used nomograms to design sailing routes to follow when doing
sea rescue. The parameters were amongst others drift, wind and sailing speed.
With this nomogram he managed to increase the efficiency in sea rescuing
substantially and was honored with a medal from the Royal Danish Navy for his
work.

Cheers
John Damm Sřrensen

Roger Johansson wrote:

"Tom Biasi" <Tom@Home.net> wrote:

Hi Roger,
You probably learned something making those diagrams,

Well, I actually didn't make them myself, I have modified one of them
so much I could consider it at least partly hand-drawn, but the other
is from a component catalog some 20 years ago.

that's good but personally I find them very difficult to read.

I don't understand that. I find them much faster and easier to use
than any calculator, especially when I don't have my hands free.
The Volt-Amp-Ohm-Watt diagram is always on my workbench and I only
have to look at it to make calculations and adjustments to circuits I
am working on.

But maybe one needs to be accustomed to reading diagrams to have use
for it. I know such diagrams are much more in use in Germany than in
USA (the first diagram came from a german handbook originally, before
I modified it).

I would encourage students to use the calculator and be aware of what it is
they are calculating.
JMHO,
Tom

Okay, thanks for your comments.

I am surprised that I have not seen such diagrams on the many web
sites about electronics I have seen.
Maybe it is a difference of culture, if people don't learn to read and
use diagrams in school they will not find them easy to work with.

I would love to find some better versions of these diagrams and I have
searched, but couldn't find any on the web.
Maybe I didn't use the right terminology and search words.
If anybody knows what such a diagram would be called in english,
please tell me.

I have uploaded two electronics diagrams on the web.
Some readers may find them useful, and I would also like to hear
comments on the usefulness of such diagrams.

The first is a diagram with voltage horisontally, current vertically,
resistance diagonally, and power on the other diagonal.

http://www.ljusdal.net/~roger/VAOW2.jpg

This means that for a resistor in a circuit you can find the point
where the voltage and current meet, and see what the resistance and
the power is. Or start with any two values and get the other two.

This is faster than using a calculator, and you don't even need one
hand free, just fix your eyes on one point and see the scales you need
to read, Very handy at the workbench when your hands are occupied with
soldering iron and components.

I have had this diagram on the front of my homemade electronics
handbook for many years and used it millions of times.
It is a lot faster than using a calculator and the formulas
Volt=Amp*Ohm and Watt=Volt*Amp

I may also be more instructive to see it graphically, because one can
follow the lines and think things like, what happens if I raise the
voltage ten times, how much will the power increase, etc..

The other diagram shows the relations between inductance, capacitance,
frequency and impedance in a similar way.

It is useful to find the impedance of a certain component at a certain
frequency, or the resonance frequency of a LC circuit, etc..

http://www.ljusdal.net/~roger/LCFO2.jpg


Sorry for the technical quality. I have tried to create these diagrams
with computer graphics but gave up and scanned in my old hand-drawn
paper copies.

Are such diagrams available, with better quality, somewhere on the
web?

--
Roger J.

--
John Damm Sřrensen, Stenkrogen 6, DK-2800 Kgs. Lyngby, 4498 6995
http://www.geocities.com/CapitolHill/6180 e-mail: johndammsoerensen@yahoo.com
http://aabenhedskomite.homepage.dk http://gladsaxelisten.8m.com

 

[Roger Johansson]

John Damm Sřrensen <john@hovedpuden.dk> wrote:

Your "diagrams" are called nomograms. See
http://mathworld.wolfram.com/Nomogram.html

I have searched for "nomograms" plus "electronics" too, a few years
ago, I didn't get much results that way either.

At least in the early 70's the design of these nomograms were taught to
electronic engineers in Denmark.

It seems it has been used more in Europe than in USA, even if some
examples in american literature exist too.

Maybe the invention of the electronic calculator made authors and
teachers believe that there was no use for nomograms anymore.

Maybe some teachers thought that it would be a kind of cheating, that
people should learn to use real equations instead.

I will keep on trying to create better versions of these diagrams
(nomograms) which are easier to read, and include extra features like
peak-to-peak scales, decibel, time constant, cycle length time, etc..

The current needs to be horisontal and the voltage vertical, because
we need more decades of current than voltage.

Just drawing the lines for 1-2-5 in each decade will make the nomogram
cleaner to read, etc..

I have also thought about color coding with gradients of color showing
for example higher power levels with deeper red, resistance with
gradients of green, and so on.

Such nomograms would help beginners to get a visual feeling for the
relationship between these units.


--
Roger J.

 

[John Jardine]

Roger Johansson <no-email@home.se> wrote in message
news:2cb1ivklfhtlk688uhgjo1ausopbodten9@4ax.com...

I have uploaded two electronics diagrams on the web.
Some readers may find them useful, and I would also like to hear
comments on the usefulness of such diagrams.

The first is a diagram with voltage horisontally, current vertically,
resistance diagonally, and power on the other diagonal.

http://www.ljusdal.net/~roger/VAOW2.jpg

This means that for a resistor in a circuit you can find the point
where the voltage and current meet, and see what the resistance and
the power is. Or start with any two values and get the other two.

This is faster than using a calculator, and you don't even need one
hand free, just fix your eyes on one point and see the scales you need
to read, Very handy at the workbench when your hands are occupied with
soldering iron and components.

I have had this diagram on the front of my homemade electronics
handbook for many years and used it millions of times.
It is a lot faster than using a calculator and the formulas
Volt=Amp*Ohm and Watt=Volt*Amp

I may also be more instructive to see it graphically, because one can
follow the lines and think things like, what happens if I raise the
voltage ten times, how much will the power increase, etc..

The other diagram shows the relations between inductance, capacitance,
frequency and impedance in a similar way.

It is useful to find the impedance of a certain component at a certain
frequency, or the resonance frequency of a LC circuit, etc..

http://www.ljusdal.net/~roger/LCFO2.jpg


Sorry for the technical quality. I have tried to create these diagrams
with computer graphics but gave up and scanned in my old hand-drawn
paper copies.

Are such diagrams available, with better quality, somewhere on the
web?

--
Roger J.

Never seen any on the web but regularly use a few from a set of 30 that
Wireless World magazine published in the late fourties?.
They called them "Nomographs" and are printed as vertical sections of
special purpose slide rules. Just use a straight edge to connect a set of
variable 'scales' together.
Yes they are useful. Repetitive calculations such as 'power dissapation' or
'diameter of wire to give minimum RF resistance' are a ball ache to
constantly run through on a calculator keypad.
regards
john

 

[Sir Charles W. Shults III]

Well, for one thing, a couple of us have explained what non-ohmic is.
Repeating myself brings a lot of my chats to a sudden halt. Here are some
examples- incandescent lamp filament, LED, transistor.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

 

[Bill Bowden]

John Larkin <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote in message news:<4qn2ivc0gumtffj073kvmjabvn21cj00at@4ax.com>...

On Thu, 24 Jul 2003 20:26:19 +0000 (UTC), "Randy "
rgwg99@acsplus.com> wrote:



John Larkin <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote in
article <fm30ivsd5d71lf8msdi2mie7vp4udplp91@4ax.com>...
: On Thu, 24 Jul 2003 05:02:56 +0000 (UTC), "Randy "
: <rgwg99@acsplus.com> wrote:
:
: >To those who may be interested,
: >I went back to the drawing board and came up with this:
: >The first step was to determine the Inductance of the primary.
:
: >L = 0.4 x 3.14 (120*120) 5000 x .003 / .750 x 10 E -08
:
: >This gave me a primary Inductance of 30 mh. I then solved for the
Inductive
: >Reactance:
:
:
: Is this your microwave transformer? This inductance seems awfully low.
: Did you account for the core permeability, cross-section, and path
: length?

Sounds like I'm about to go to school but, yes, I accounted for core
permeability: 5000 for soft Iron, the cross section is .003 sq. m and "l",
according to the text, is the length of the coil. Correct me if I'm wrong.
The only thing I did not account for is losses which, If I've been led
right, is about 2 to 3%.

I'm far too lazy to deconstruct your numbers back to the equation, but
I don't thing "length of the coil" makes sense. Length of the magnetic
path is relevant, and L goes inverse with this one.

Hey, hook it up to 120 and measure the primary current! It will likely
be bigger than theoretical, as most such trannies run a bit into the
core saturation region (less copper+iron = higher flux density = more
losses = cheaper transformer).

Magnetics are always a pain.

John

Not only the saturation problem, they also usually weld the
transformer laminations together for easy assembly and
to stop buzzing noises. Nobody likes to hear buzzing noises
while cooking.

I tried a junk MO transformer with no load and it drew
3 amps, and the core was too warm to touch within a few
minutes. But it was very silent, no hum or buzz.

-Bill