Chip with simple program for Toy

rab wrote:

Hi,

I have a discussion with a collegue. We have material with 1 M/square
surface resistance. What is the resistance between 2 points (diameter 1 mm
round) seperated by 20 mm. Is there a formula somewere or a place to look.

Thanks
Ronald


not sure on your question format "1 M/square" ?

1 meter per square? or 1 meg ohm per square?

and when you say round?, are we talking about a
round like in a doughnut? or a sphere ?
 
"rab" <xyzyrbuining@xs4all.nl> wrote in message
news:421f480d$0$28993$e4fe514c@news.xs4all.nl...

I have a discussion with a collegue. We have material with 1 M/square
surface resistance. What is the resistance between 2 points (diameter 1 mm
round) seperated by 20 mm. Is there a formula somewere or a place to look.
Look for the formula giving the capacitance
between adjacent round conductors. Except
for the constant term and the fact that one is
per unit length and the other not, the formula
will be the same. Just substitute conductivity
for permeability per unit length.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
On Thu, 24 Feb 2005 08:46:10 -0700, Jim Thompson
<thegreatone@example.com> wrote:

its FidoCAD

Why not then just use a readily available, and free, program such as
Mike Engelhardt's LTSpice? (Or an old copy of MicroSim Schematics for
that matter?)
will check for those ones later .. :)
--
Regards , SPAJKY ÂŽ
& visit my site @ http://www.spajky.vze.com
"Tualatin OC-ed / BX-Slot1 / inaudible setup!"
E-mail AntiSpam: remove ##
 
On Fri, 25 Feb 2005 16:43:59 +0100, "rab" <xyzyrbuining@xs4all.nl>
wrote:

Hi,

I have a discussion with a collegue. We have material with 1 M/square
surface resistance. What is the resistance between 2 points (diameter 1 mm
round) seperated by 20 mm. Is there a formula somewere or a place to look.

Thanks
Ronald
There is an equation. Google "surface resistance two contacts" or
something similar.

(rho/dz)log(L/r)/pi or something.

John
 
Incidentally, what software do you use for rendering your
circuits designs as they appear on the links you have
provided?
The software is an old DOS program called "Colorix VGA Paint" 1989.

It's similar to Windows "Paint" with more features.
It's easy to copy and paste, and move things around.
Windows "Paint" can do the same thing, but has limited
editing features.

-Bill
 
wrongaddress@att.net wrote:
But I forgot to mention the Colorix program produces .GIF files
directly while Windows Paint only produces .BMP files which need
conversion. There are utilities to convert formats, but it's nice to
get the finished drawing in the right format without conversion
problems.
FYI, Paint under XP can save files as GIF, TIFF, JPG, and PNG, as well
as various levels of bitmap. You need to change the popup menu on the
saveas dialog to indicate the proper format.


--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
 
Chris W wrote:

. . .

I'm working on a wiring diagram to look at if this isn't enough
information. Thanks for the help.
That didn't take near as long as I thought. Here is the old and what I
hope will work for the new wiring diagram.

http://www.thewishzone.com/cdw/index.php?image=TotalGymWiring.gif


--
Chris W

Gift Giving Made Easy
Get the gifts you want &
give the gifts they want
http://thewishzone.com
 
A coil of coax of appropriate length in one channel might be a solution.
You can easily view the phase difference of the signals on a two channel
scope.

--

73
Hank WD5JFR
"stevieboy01" <stephen_cochrane@hotmail.com> wrote in message
news:8a656a08.0502270504.70836b63@posting.google.com...
I am attempting to characterise a phase shift in a channel so that I
can compensate it at the receiver end using a phase equalizer. I need
a method which produces a phase shift curve with more measurements
than a Lissajous method produces. I was thinking possibly a phase
shift oscillator may be the way to go with each stage producing a 45
degree shift, but I am unsure how to use this. I want to define the
frequency and calculate the resulting shift. Also, I am not sure how
to use an equalizing filter. I would probably use an all pass filter
but how can I define where the curve goes?


Since I am working on a project already in place, I'm afraid the
recievers have been defined already. They are Radiometrix BIM 418-40
transceivers.

http://www.radiometrix.co.uk/products/bimsheet.htm

I will elaborate more........

At present we are using a 4 level ASK digital transmission being fed
into a DAC for RF transmission. At the receiver end, it is being
converted back, naturally using an ADC.

I am firstly looking to shape the pulse going in using a bandpass of
approx 100Hz - 20kHZ. This should eliminate high frequency components
since there is a high level of ringing as too much energy is trying to
get through the channel. However, because of the associated phase
shift in a non linear filter, I will have to compensate at the
receiver. The transceivers already introduce a slight phase shift,
which I am hoping to eliminate with an equalizer. The eye diagram at
the receiver is poor so, especially with 4 level signalling, I hope to
improve it.

Cheers

Steve
 
After receiving feedback from the sci.electronics.basics newsgroup I have
redesigned the LM386 audio amplifier I am building on a breadboard.

At left of the breadboard is a Radio Shack condenser mic, biased with a 1K
resistor, the output coupled via a 1uF capacitor to an noninverting
amplifier based on an LM741 op-amp.

The + input of the LM741 is set to 1/2 the supply voltage by a voltage
divider made of 2 10Kohm resistors. The feedback resistor from the output to
the - input is 470Kohms, and there is a 1Kohm resistor in series with a
100uF capacitor from the - input to ground. The gain from this noninverting
amp is designed to be 470.

The output of the LM741 is coupled through a 10uF capacitor to the + input
of the LM386. The output of the LM386 is passed to a snubber and a 220uF
capacitor in series with the speaker. I also placed a 220uF capacitor across
the power and ground pins.

To prevent motorboating oscillations I have separated the power supplies so
one 9V battery powers the input mic and the LM741 and another 9V battery
powers the LM386 and speaker.


Result: The circuit no longer has motorboating oscillations. However, the
speaker only produces sound output when I tap or blow on the mic. Other
sounds that don't physically shake the mic are not passed.

I thought the gain was not high enough, so I bypassed the 1 and 8 pins of
the LM386 to increase its gain to 200. When I did so it produced a loud
piercing shriek.

I was wondering whether I have unintentionally created a low-pass filter
which prevents sounds in the vocal range from being amplified.

Any feedback will be appreciated.
 
Are you sure the loud shriek isn't just feedback from the mic?


"zero" <slave@discussions.com> wrote in message
news:458Xd.24674$534.22648@twister.nyc.rr.com...
After receiving feedback from the sci.electronics.basics newsgroup I have
redesigned the LM386 audio amplifier I am building on a breadboard.

At left of the breadboard is a Radio Shack condenser mic, biased with a 1K
resistor, the output coupled via a 1uF capacitor to an noninverting
amplifier based on an LM741 op-amp.

The + input of the LM741 is set to 1/2 the supply voltage by a voltage
divider made of 2 10Kohm resistors. The feedback resistor from the output
to
the - input is 470Kohms, and there is a 1Kohm resistor in series with a
100uF capacitor from the - input to ground. The gain from this
noninverting
amp is designed to be 470.

The output of the LM741 is coupled through a 10uF capacitor to the + input
of the LM386. The output of the LM386 is passed to a snubber and a 220uF
capacitor in series with the speaker. I also placed a 220uF capacitor
across
the power and ground pins.

To prevent motorboating oscillations I have separated the power supplies
so
one 9V battery powers the input mic and the LM741 and another 9V battery
powers the LM386 and speaker.


Result: The circuit no longer has motorboating oscillations. However, the
speaker only produces sound output when I tap or blow on the mic. Other
sounds that don't physically shake the mic are not passed.

I thought the gain was not high enough, so I bypassed the 1 and 8 pins of
the LM386 to increase its gain to 200. When I did so it produced a loud
piercing shriek.

I was wondering whether I have unintentionally created a low-pass filter
which prevents sounds in the vocal range from being amplified.

Any feedback will be appreciated.
 
"zero" <slave@discussions.com> wrote:

Result: The circuit no longer has motorboating oscillations. However,
the speaker only produces sound output when I tap or blow on the mic.
Other sounds that don't physically shake the mic are not passed.
As tempus said, the most likely problem is feedback between the
loudspeaker and the mic. To remove that possibility use earphones instead
of a speaker.

The 741 is very unsuitable as mic preamp. It generates a lot of noise all
by it self.

Look at other mic preamp circuits. You will find better alternatives.
Some mic preamp circuits are very simple, like a single bipolar
transistor. Try something like that instead. Or at least replace the 741
with a better opamp, like the TL071 (071/072/074).


--
Roger J.
 
Could you direct me to a web page or a book which details how to design
pre-amps and audio amps? I'd like to learn how to avoid feedback, what are
the qualities of good pre-amps, etc.



"Roger Johansson" <no-email@no.invalid> wrote in message
news:Xns961341DCCAFA586336@81.174.12.30...
"zero" <slave@discussions.com> wrote:

Result: The circuit no longer has motorboating oscillations. However,
the speaker only produces sound output when I tap or blow on the mic.
Other sounds that don't physically shake the mic are not passed.


As tempus said, the most likely problem is feedback between the
loudspeaker and the mic. To remove that possibility use earphones instead
of a speaker.

The 741 is very unsuitable as mic preamp. It generates a lot of noise all
by it self.

Look at other mic preamp circuits. You will find better alternatives.
Some mic preamp circuits are very simple, like a single bipolar
transistor. Try something like that instead. Or at least replace the 741
with a better opamp, like the TL071 (071/072/074).


--
Roger J.
 
"zero" <slave@discussions.com> wrote:

Could you direct me to a web page or a book which details how to design
pre-amps and audio amps? I'd like to learn how to avoid feedback, what
are the qualities of good pre-amps, etc.
You could begin with a very simple circuit, like this
http://koti.mbnet.fi/~huhtama/ele/index.php?si=kyt02.sis&pa=j

Practically any bipolar npn transistor will work in that circuit, take what you have.
But you can try different npn transistors to get the best sound.
(the text is in finnish, but you don't need it. read the circuit and the parts list)

There are enormous amounts of information on the web about this.

Just use google and search for
mic preamp circuit
for example, and follow the links to the world of circuits and information about electronics.

High quality mic preamp:
http://www.minidisc.org/mic_preamp/Simple%20Stereo%20Electret%20Mic%20Preamp.htm

http://www.ee.washington.edu/circuit_archive/circuits/micamp.html


--
Roger J.
 
Fred Abse wrote:
On Fri, 11 Mar 2005 13:15:25 +1300, Terry Given wrote:


1) Choose a phasor on which to orient your rotating reference frame - eg
AC line voltage. By definition this transformed phasor is purely real
(or purely complex).

2) Calculate the transformed real and imaginary parts by taking the
original phasor and multiplying by exp(j*theta) [in a 3-phase system we
typically assume some symmetry and perform a 3-phase to 2-phase
transformation, resulting in a single complex phasor.

3) use the imaginary (or real) part of the transformed phasor as the
feedback signal for a PI controller to calculate the actual w. The
setpoint for this PI controller will be zero, again by definition

4) the output of the PI controller is angular speed, w. Usually the PI
controller has the desired w (eg 2pi*50Hz) added to its output, so it
only corrects the phase error, but its not strictly necessary - the PI
controller will eventually get the right w.

5) integrate the estimated w, giving theta = wt

6) use this theta in the phasor transform of step 2.



Are we allowed to Park here?

:)
<Snort> LOL

Cheers
Terry
 
JazzMan <No_Spam@airmail.net> wrote:

If I go with a photo process, I'd like to make my own sensitized
boards because the pre-sensitized boards are fairly expensive. Is
that something that's possible? Is there a spray or coating that
I can apply to make a board photo-resist ready?
I have tried those products and I do not recommend them.
It is very difficult to get a layer which has the same thickness
everywhere, and that ruins the etching process.

It is much better to buy readymade photosensitive pcb board material.

If you choose to make your own after all you can spray in the middle of
the board and then rotate the board very fast (with a motor) to spread
out the photoresist evenly in a thin layer. I have not tried this but I
heard about that method.

Or mount two boards on each side of the rotation center, spray the inner
edges, rotate fast to force the liquid to flow over the whole surface,
and the excess liquid is thrown off the outer edge.

You also need to do it in a dust free environment which can contaminate
the photoresist before it has dried in an oven set to low heat.


--
Roger J.
 
JazzMan wrote:

I've got a small project that I want to make about two hundred
copies of. The board is 1" x 1.25" single side single layer
with 10 through holes. I don't need silkscreening or special
features, just the etched board. I've got accurate drawings
in AutoCad. What would be the least expensive way to get these
made? Time isn't so much a factor.

I've thought about making them myself, but haven't got experience
with the photo processes. The largest board I've made so far is
5.5" x 6" with a couple of hundred through holes single sided, I
used the technique of laser printing the reverse layout onto the
backing sheet of labels, then ironing the toner onto the board,
touching up defects with a Sharpie permanent marker. That worked
ok, but it wasn't as professional-looking as I'd like these to look.

If I go with a photo process, I'd like to make my own sensitized
boards because the pre-sensitized boards are fairly expensive. Is
that something that's possible? Is there a spray or coating that
I can apply to make a board photo-resist ready?

Thanks!

JazzMan
http://www.expresspcb.com

they have a 3 boards for $51.00
but they don't specify the size etc.
they maybe large boards in which case
you could mask multiple copies of the
same mini board on the larger one and
then slice them up your self using a
scroll saw.
i am not sure, look at the sight.
 
Jamie wrote:
JazzMan wrote:

I've got a small project that I want to make about two hundred
copies of. The board is 1" x 1.25" single side single layer
with 10 through holes.

http://www.expresspcb.com

they have a 3 boards for $51.00
but they don't specify the size etc.
they maybe large boards in which case
you could mask multiple copies of the
same mini board on the larger one and
then slice them up your self using a
scroll saw.
i am not sure, look at the sight.
Just checked them out, that's three 2.5" x 3.8" boards.
Too expensive for what I want to do.

JazzMan
--
**********************************************************
Please reply to jsavage"at"airmail.net.
Curse those darned bulk e-mailers!
**********************************************************
"Rats and roaches live by competition under the laws of
supply and demand. It is the privilege of human beings to
live under the laws of justice and mercy." - Wendell Berry
**********************************************************
 
JazzMan wrote:
I've got a small project that I want to make about two hundred
copies of. The board is 1" x 1.25" single side single layer
with 10 through holes. I don't need silkscreening or special
features, just the etched board. I've got accurate drawings
in AutoCad. What would be the least expensive way to get these
made? Time isn't so much a factor.
Try www.futurlec.com. It may be cheaper to put a bunch of them on a
board, and then cut them up later. Send them email, they may be willing
to help out with that.

www.futurelec.com

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
 
On Sun, 13 Mar 2005 18:15:25 -0600, JazzMan <No_Spam@airmail.net>
wrote:

I've got a small project that I want to make about two hundred
copies of. The board is 1" x 1.25" single side single layer
with 10 through holes. I don't need silkscreening or special
features, just the etched board. I've got accurate drawings
in AutoCad. What would be the least expensive way to get these
made? Time isn't so much a factor.
Check out http://www.4pcb.com/ . Look under "Specials".
 
Hello,
You can send your file to me. We can help you to do these boards. Only
0.02 US$ per cm*cm for FR4 single side. But the price does not include the
transfer fee to you. You can send to fjq at qingdaonews.com

Best regards,
Feng
 

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