Driver to drive?

Hi Rich,

Hasn't somebody, somewhere, already figured out how to make a
transponder? Is the OP trying to reinvent the wheel?

http://www.google.com/search?q=transponder&btnG=Search


Yes, but if you look at the specs the OP desires and narrow the search
down to those

http://www.google.com/search?as_q=transponder+nsec+timing&num=100&hl=en&ie=UTF-8&btnG=Google+Search&as_epq=precision&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_nlo=&as_nhi=&as_occt=any&as_dt=i&as_sitesearch=&safe=images

then you are quickly relegated to very high frequencies and not a
regular radio. Doesn't mean it can't be done but it kind of hints that
it might indeed be a challenge.

Regards, Joerg

http://www.analogconsultants.com
 
Joerg wrote:


One low cost way to do this in the real world is to detect the umpteenth
zero crossing of the 1KHz signal. Just pick one and stick to that. It
has to be the exact zero crossing, not a few millivolts up or down. That
could be achieved by a differential measurement. This is the way it used
to be done in Doppler ultrasound where you sometimes have to measure
minute movements of blood or vessel walls. This strategy would get rid
of the uncertainty, drift and what not of an additional AM detector.

If I understand, I don't think you're saying to count zero crossings
until you get to the one you've picked, and use that crossing as a time
marker, are you? I think you're saying instead to take sufficient time
to be able to make an accurate differential measurement of zero
crossings, and the amount of time needed can be guesstimated as waiting
until X zero crosings have occurred. Then that last zero crossing time
can be used as the time marker that is needed. Right?

So, assume 1 kHz tone amplitude of 1 Vp-p. In 50 nsec after crossing
zero its amplitude will be 0.2 mV, and that's what has to be detected in
the presence of a noise floor and all the other stuff.

I had a similar idea in mind, and would appreciate your comments.
Suppose you let the tone run for a while (hundreds of msec would be OK)
so that a PLL can be locked to it. At the source, the tone is then cut
off abruptly. It would be cut off at the peak of its waveform so that
the transition from on to off would be as abrupt as possible.
(Unfortunately filtering ahead of the PLL detector would round off the
transition contributing to errors.)

Given that you've had a long time to close a PLL on the tone, its abrupt
transition straight down from the voltage maximum, and the fact that
this measurement is being made at 1 Volt rather than mucking around in
the receiver's noise floor, might this approach work?

Thanks for taking the time to read all this ... :eek:)

George
 
On Monday 04 October 2004 05:17 pm, Carl Gilbert did deign to grace us with
the following:

Hi

I am looking to build a basic heating system using the attached design.
It incorporates a 555, a variable resistor, some diodes and other bits and
pieces I don't understand but soon will.

The only problem is finding/making a board for it. I made a board in
school once where we used some sort of pen to draw the outline and dipped
the thing in acid.

With cost as main the limitation here, what is the easiest way to achieve
my
goal. Can I print my own board at a reasonable price (<Ł20-Ł30) for
resources or is there a service which I could use to get a board made for
me?

The only problem is, I would only want about 3 or 4 boards so I should
imagine most organisations would not be interested in such a small
project.

Design is courtesy of Dave McCarter. This can be found at:
http://www.astro.uwo.ca/~rasc/HEATER.pdf
You can get transparent film that you can print on with a laser or
inkjet, and photosensitive board material. Print as many copies of
the circuit as you want on one sheet - you could do 6-up on a
letter-size, then expose and etch them all at once (on the one
board, that is), then shear the board (or score it and snap it).

Have Fun!
Rich
 
George W wrote:

[large snip]

So, assume 1 kHz tone amplitude of 1 Vp-p. In 50 nsec after crossing
zero its amplitude will be 0.2 mV, and that's what has to be detected in
the presence of a noise floor and all the other stuff.

I had a similar idea in mind, and would appreciate your comments.
Suppose you let the tone run for a while (hundreds of msec would be OK)
so that a PLL can be locked to it. At the source, the tone is then cut
off abruptly. It would be cut off at the peak of its waveform so that
the transition from on to off would be as abrupt as possible.
It sounds like you're expecting this signal to now suddenly fall from 1 volt to
zero volts in zero time ?

How fast do you think it can do this through a 3KHz (or 10KHz or whatever)
bandwidth channel ?

Gibbo
 
Rich Grise wrote:


Hasn't somebody, somewhere, already figured out how to make a
transponder? Is the OP trying to reinvent the wheel?

Hi Rich. I'd love to find something that exists but I believe the
requirements in this case call for a home grown solution.

If this were a conventional transponder (RX straight thru to TX in real
time) the radio would have to operate in duplex mode. Unfortunately I'm
limited to operating in simplex. I agree with Joerg that it's probably
doable but a challenge!

George
 
"Roberto Diana" <dianaroberto@virgilio.it> schrieb im Newsbeitrag
news:801dd266.0410050346.528deb37@posting.google.com...
Are these library available for a free download? Please, let me know
what's the name of this library and where can I find on Internet.
Thank you very much.
Hello Roberto,
you haven't understood the joke from Boris.
He said you can make your own model with any of those simulation programs.

Best Regards,
Helmut


Roberto



Boris Mohar <borism_-void-_@sympatico.ca> wrote in message
news:<5kc3m0h51c5fujcdc9dt076hbuhbr4p2uu@4ax.com>...
On 4 Oct 2004 10:31:29 -0700, dianaroberto@virgilio.it (Roberto Diana)
wrote:

Hi to all,
I would like to know if a suitable library, for AD8302 IC, is
available for Orcad 9.2 or Electronic workbench Multisim 2001.
Please, reply me as soon as possible!
Bye,

Roberto

Suitable library editor is available in both.


Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/

void _-void-_ in the obvious place
 
"John Larkin" <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> schreef in
bericht news:v4l5m0lvf3nrknhld3l8eiojc125t93vji@4ax.com...
On Tue, 05 Oct 2004 16:55:33 GMT, Rich Grise <null@example.net> wrote:

On Monday 04 October 2004 08:11 pm, John Larkin did deign to grace us
with
the following:

You are describing cigarettes. They kill over 8,000 Americans a week,
in a most gruesome and painful manner.


It figures that a bushist would be an antismokerist, as well. Just love
those newfangled religions, don't you John Larkin?


Please explain how that "figures." I hate smoking because it keeps
killing people I love.
Not all of them, I hope, but also look at the bright
side; it also kills people you hate ;)

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
Hi George,

If I understand, I don't think you're saying to count zero crossings
until you get to the one you've picked, and use that crossing as a
time marker, are you? I think you're saying instead to take
sufficient time to be able to make an accurate differential
measurement of zero crossings, and the amount of time needed can be
guesstimated as waiting until X zero crosings have occurred. Then
that last zero crossing time can be used as the time marker that is
needed. Right?
Actually in your case you'd have to also detect the onset of the 1KHz
packet and this detection needs to be accurate enough never to slip a
cycle. This is because, if I understand correctly, the timing of the
event is unknown. After that, you can pick any zero crossing as long as
it is always the same. Integrating the measurement routine over several
crossings would improve the SNR and thus your accuracy. So the longer
the tone lasts the more accuracy you can squeeze out.

So, assume 1 kHz tone amplitude of 1 Vp-p. In 50 nsec after crossing
zero its amplitude will be 0.2 mV, and that's what has to be detected
in the presence of a noise floor and all the other stuff.
There is one of the challenges. It can be done but it is best to use a
differential method to avoid offset errors and you need a good strong RF
signal coming in. Detecting several crossings and integrating the
results will improve the SNR and jitter.

I had a similar idea in mind, and would appreciate your comments.
Suppose you let the tone run for a while (hundreds of msec would be
OK) so that a PLL can be locked to it. At the source, the tone is
then cut off abruptly. It would be cut off at the peak of its
waveform so that the transition from on to off would be as abrupt as
possible. (Unfortunately filtering ahead of the PLL detector would
round off the transition contributing to errors.)

Given that you've had a long time to close a PLL on the tone, its
abrupt transition straight down from the voltage maximum, and the fact
that this measurement is being made at 1 Volt rather than mucking
around in the receiver's noise floor, might this approach work?
The abrupt shut-off would be of no concern if you stop using the PLL
just before that event. It should be no problem because the length of
the transmission is under your design control so the receiver would
"know" when to quit logging the PLL.

A PLL is a good idea but more work to design. However, considering all
the chips you can get nowadays it might have become the easier option by
now. The tone needs to be long enough for the PLL to level off at the
desired accuracy. Here you have the usual trade-off between slower loop
response or more noise. I am afraid a few 100msec won't cut it at all
here. It is only a few hundred cycles with a 1KHz tone. Not a whole lot.
The fancy approach would be a multi-loop PLL but now we might enter the
terrain of "over-sophistication".

Yet another approach is to send out a unique binary sequence and run a
matched digital filter against it. There are several codes that are used
for this purpose and probably someone makes chips with such a code and
filter built in. That would give you absolute (time of onset) and
relative (50nsec spec) at the same time. I am partial to the zero
crossing scheme. But then again, maybe that is because I am an analog guy.

Regards, Joerg

http://www.analogconsultants.com
 
Hi Frank,

$5.33 ! What's so special?


When a rather mundane part becomes expensive it might just be because it
is about to become extinct. Or it might be a specialty part with low
market penetration.

Regards, Joerg

http://www.analogconsultants.com
 
On Tue, 05 Oct 2004 17:33:15 GMT, George W
<look_below@my_signature.com> wrote:


If this were a conventional transponder (RX straight thru to TX in real
time) the radio would have to operate in duplex mode. Unfortunately I'm
limited to operating in simplex. I agree with Joerg that it's probably
doable but a challenge!
---
Can you tell us what it is you're trying to accomplish?

Not just the "I want to use a 1kHz tone to do this..." part, but the
application?

--
John Fields
 
On Tue, 05 Oct 2004 13:06:56 GMT, Fred Bloggs <nospam@nospam.com> wrote:

the
SCUD is just a big piece of inaccurate junk, optimized for throw range
and de-optimized for accuracy- it is a civilian terror weapon to be
lobbed into a broad urban area, it is worthless against military
targets.
SCUD was jokingly said (by some US soldiers there in 1991) to be Iraqi for "Yugo
Full of Explosives Launched by Catapult."

Jon
 
"Johan Karremans" <johankarremans@hotmail.com> wrote in message news:26d2168f.0410050419.255e7d50@posting.google.com...
Can somebody tell me what the substitute ic is from ic 74LS173.
If you need the ic, JDR has them in stock for .99...Paul

http://www.jdr.com/interact/item.asp?itemno=GR-7400G3

Note the part numbers are not in sequence.
 
On Tue, 5 Oct 2004 20:38:42 +0200, "Frank Bemelman"
<f.bemelmanx@xs4all.invalid.nl> wrote:

"John Larkin" <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> schreef in
bericht news:v4l5m0lvf3nrknhld3l8eiojc125t93vji@4ax.com...
On Tue, 05 Oct 2004 16:55:33 GMT, Rich Grise <null@example.net> wrote:

On Monday 04 October 2004 08:11 pm, John Larkin did deign to grace us
with
the following:

You are describing cigarettes. They kill over 8,000 Americans a week,
in a most gruesome and painful manner.


It figures that a bushist would be an antismokerist, as well. Just love
those newfangled religions, don't you John Larkin?


Please explain how that "figures." I hate smoking because it keeps
killing people I love.

Not all of them, I hope, but also look at the bright
side; it also kills people you hate ;)
I don't hate anybody enough to want them to die the way Greta or
Sheldon died.

John
 
Mac foo@bar.net wrote:

On Sun, 03 Oct 2004 02:23:08 +0000, ChrisGibboGibson wrote:
[snip]

That was the basis of my post a few days ago regarding a highly accurate CC
generator.

Until I actually tried this (with Fred's CC generator) I couldn't believe
the
accuracy that could be got from such a small outlay.

Gibbo

What exact circuit did you use for the CC generator? You were going to use
a source rather than a sink, weren't you?
I used Fred's original sink circuit that he posted, turned it upside down and
swapped npn for pnp, n channel for p channel.

Gibbo
 
John Larkin wrote:

[snip]

Comparing the results with a 10 digit meter I got accuracy within 0.005% of
the
Vrefs I was using. That's quite amazing for a dollars worth of comparator
and
discretes.

10 digit DVM? Who makes that?
Keithley, circa early 80s

Gibbo
 
Frank Bemelman wrote:
"Joerg" <notthisjoergsch@removethispacbell.net> schreef in bericht
news:jvA8d.24422$QJ3.15764@newssvr21.news.prodigy.com...

Hi Johan,

74HCT173?

TI has them but they are very expensive:

http://focus.ti.com/docs/prod/folders/print/cd54hct173.html



$5.33 ! What's so special?
Whoa. For that amount I get a 64 Flipflop CPLD doing 200MHz.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
Boris Mohar wrote:

On 4 Oct 2004 10:31:29 -0700, dianaroberto@virgilio.it (Roberto Diana) wrote:

Hi to all,
I would like to know if a suitable library, for AD8302 IC, is
available for Orcad 9.2 or Electronic workbench Multisim 2001.
Please, reply me as soon as possible!

Suitable library editor is available in both.
The AD8302 is one of those parts where a simulation is one
thing and actually reaching the specifications quite another.
Since its function is readily understood, I'd focus on
getting those 60dB dynamic range from these dual 2.7GHz
log amps, especially in the presence of a controller.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
Hi Spehro,

They are in ceramic DIP, probably kept in production for military
applications that don't mind the cost.


The SOIC is only around 25 cents US. Still quite a bit for four flip
flops. But LS stuff as the OP was requesting will likely become ever
harder to obtain so it makes sense to migrate the design at least to HCT
if he can. It it isn't running fast I'd see if it can be done in the
4000 series. That has enjoyed a product life almost like the VW Beetle
and is cheap.

Regards, Joerg

http://www.analogconsultants.com
 
"Kenneth Keeley" <kenkeeley@hotmail.com> schreef in bericht
news:450651a0.0410042042.18275deb@posting.google.com...
Jonathan Kirwan <jkirwan@easystreet.com> wrote in message
news:<ved1m09rkujdg8cs7i9dd75pub65ppccej@4ax.com>...
On 3 Oct 2004 19:14:34 -0700, kenkeeley@hotmail.com (Kenneth Keeley)
wrote:

I am building a small 68000 computer from the ground up. I would
like to build a keyboard interface that would be able to use a pc
keyboard. Does anybody know of a simple circuit design that I could
use. I did find a design some time ago for an XT keyboard interface
using a serial to parallel convertor. Would this still work with an AT
keyboard. A link to a Circuit Diagram or at least a write up on a
circuit diagram would be great.

I have the IBM docs on the electrical and software on the AT keyboard and
I
think there are a few pages on the web with this, also. Do I gather you
don't
actually want to do the electrical interface design, though? (It's not
hard.)

Have you already looked around on the web? If so, what have you found
that does
NOT meet your needs but does seem to get kind of close?

Jon

I have looked around the web but haven't found any well shown designs
all of the ones I have found have talked about using a PIC or micro
controller to interface with the keyboard. Do you know where I could
find the IBM docs that you referred to.

Kenneth
Didn't you find www.beyondlogic.org ? All you need to know about the
AT-keyboard interface is available, even a design using a Motorola micro to
convert the AT keyboard codes to RS232 serial. To use it you need to build a
serial RS232 interface at the side of the computer. Which needs address
decoding, an ACIA and some level converter. (Unless you decide skip these
levelconversion on both sides.)

You can use the same address decoding to control some buffers that give you
plenty of I/O lines to make the 6800 handle the keyboard itself. The address
decoding controls busbuffers like LS254 for input and LS364 as an output
register. LS14s were commonly used input buffers and LS125 simulated open
collector output buffers (But you can use real open collector buffers or
even transistors as well). Another description can de found at
http://panda.cs.ndsu.nodak.edu/%7Eachapwes/PICmicro/PS2/ps2.htm
A full AT keyboard specification can be found on
http://www.electronic-engineering.ch/microchip/projects/keyboard/v2xx/keyboard_v2xx.html
A schematic at
http://members.lycos.co.uk/leeedavison/6502/atkey/
This last one is mented for a 6502, but you can connect it to a 68000
processor the same way, even simpler then my proposal above.

If you can't find info like this or can't work with it *I* think you'll have
a long way to go before you have build a 68000 computer.

petrus bitbyter





---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.771 / Virus Database: 518 - Release Date: 28-9-2004
 
John Woodgate wrote:

I read in sci.electronics.design that Rich Grise <null@example.net
wrote (in <pIz8d.4727$Sl2.2910@trnddc09>) about 'What does J-K in J-K
flip flop indicate?', on Tue, 5 Oct 2004:


I was assuming that the "R" was "Reset" and the "S" was "Set." But what
could "J" and "K" stand for? :)


Jog and Kick, of course. What do you think Q and Q-bar stand for? And
the D in D-type and the T in T-type.

Jump, Kill
Delay
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