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Frequency down-conversion with passive circuitry?

J

Jeroen

Jan 1, 1970
0
Is it possible to come up with a passive circuit, containing
only resistors, coils, capacitors and diodes, which when
stimulated with a given frequency produces a *lower* frequency
as output? Some blackbox that produces, say, f/2 for an input
frequency of f?

Bonus points are available if the circuit puts out several
different frequencies <f. ;-)

What gives?

Jeroen Belleman
 
J

Jan Panteltje

Jan 1, 1970
0
Is it possible to come up with a passive circuit, containing
only resistors, coils, capacitors and diodes, which when
stimulated with a given frequency produces a *lower* frequency
as output? Some blackbox that produces, say, f/2 for an input
frequency of f?

Bonus points are available if the circuit puts out several
different frequencies <f. ;-)

What gives?

Jeroen Belleman

Na, perhaps *tunnel* diode oscillator tuned to f/2, and sort of hard locked?
 
J

Jeff Johnson

Jan 1, 1970
0
Jeroen said:
Is it possible to come up with a passive circuit, containing
only resistors, coils, capacitors and diodes, which when
stimulated with a given frequency produces a *lower* frequency
as output? Some blackbox that produces, say, f/2 for an input
frequency of f?

Bonus points are available if the circuit puts out several
different frequencies <f. ;-)

What gives?

Jeroen Belleman

As linear components it is mathematically impossible to do so. Linearity
dictates that no new frequency components are created. Of course any
component is only linear in a certain range so it is not at all impossible
to do so with the components you have suggested. One just has to find the
right way to use them and take advantage of their non-linearity. The result
may not be all that great though...
 
Q

qrk

Jan 1, 1970
0
Is it possible to come up with a passive circuit, containing
only resistors, coils, capacitors and diodes, which when
stimulated with a given frequency produces a *lower* frequency
as output? Some blackbox that produces, say, f/2 for an input
frequency of f?

Bonus points are available if the circuit puts out several
different frequencies <f. ;-)

What gives?

Jeroen Belleman

Is a diode considered a passive device?
 
J

John Nagle

Jan 1, 1970
0
Is it possible to come up with a passive circuit, containing
only resistors, coils, capacitors and diodes, which when
stimulated with a given frequency produces a *lower* frequency
as output? Some blackbox that produces, say, f/2 for an input
frequency of f?

Yes, but you need some nonlinear passive component.

Saturable magnetics work. Classic telephony gear
used these extensively, since they don't wear out.
The classic Western Electric ring generator (48VDC
in, 88V 20Hz out) is an example.

John Nagle
 
J

Jeroen

Jan 1, 1970
0
Diodes aren't linear--they're nonlinear both in conductance and in
susceptance. A parametric amplifier produces signal and idler
frequencies that sum to its pump frequency.

Sorry to be a bit absent after my first question, but we're
gearing up to restart the accelerators here by the end of the
month and work took precedence.

Phil's last remark is precisely what I was after. I'm perfectly
OK with nonlinear inductors or capacitors instead of diodes, too.

The reason I asked this question, I must confess, is that in an
article I came across recently, the authors flatly state that it
is impossible to do so without invoking quantum physics theory.
Clearly, if it is possible using some non-linear passive circuitry,
this affirmation is false. Now I must hunt down an example...

For those interested, the article I referred to is: B. Pearson,
D. Jackson, "A hands-on introduction to single photons and quantum
mechanics for undergraduates", A. J. Phys. 78(5), May 2010.

Thanks everyone for their contributions.

Regards,
Jeroen Belleman
 
J

Jeroen

Jan 1, 1970
0
Quantum mechanics is crap, bullshit, phantasy, nonsense.
CERN is a joke.
ITER is idiotic.
LIGO is insane.

Blame it on... misunderstanding Planck's constant.
So blame it on Einstein.

I should invest some time in a rebuttal, but I'm not really
well armed.

Let me put it this way: CERN draws scientists to Europe.
Science is at the basis of all innovative economic activity.
Accelerator physics has spin-offs that find use in other
places. Proton and carbon beam therapy against cancer,
imaging radiation detectors for X-raying whole trucks,
synchrotron light sources for all sorts of purposes.
Technologies developed for or by CERN or other physics
institutes, and which would not have been available
otherwise at a reasonable price, find use in other places:
The World Wide Web, very accurate DC current transformers,
cryogenics, super conductivity, scintillating plastics and
crystals, big magnets, precise surveying, radio frequency
equipment and techniques, vacuum, etc, etc.

CERN pays my salary, so it's certainly no joke to me. It's a
fascinating place to work. Apart from the technical aspects
of the place, there is the fact that all cultures and
nationalities of the world are represented here, working
closely together for a single purpose: Understanding how the
universe works.

I'd love to pull the rug from under quantum mechanics.

Jeroen Belleman
 
R

Rich Grise

Jan 1, 1970
0
Jeroen said:
Is it possible to come up with a passive circuit, containing
only resistors, coils, capacitors and diodes, ...

I've always had this kind of nagging question in my head - does
a diode really qualify as "passive?" Maybe it's just that they're
so blatantly nonlinear!

Anybody wanna start a holy war over it? >:->

Thanks,
Rich
 
I've always had this kind of nagging question in my head - does
a diode really qualify as "passive?" Maybe it's just that they're
so blatantly nonlinear!

No power added == passive (ever heard of "passive RFID tags"?)
Anybody wanna start a holy war over it? >:->

Too late.
 
A

Adrian Tuddenham

Jan 1, 1970
0
Clearly, if it is possible using some non-linear passive circuitry,
this affirmation is false. Now I must hunt down an example...

A ringing current generator used by the U.K. Post Office Telephone
service in the late 1950s and 1960s used a selenium rectifier and
resonant circuit to generate 16.666 c/s to operate telephone bells.
 
J

Jeroen Belleman

Jan 1, 1970
0
Jan said:
[The WWW] has nothing to do with the 'goal' (if any) that
CERN had or has.
And internet comes from a mil source.

That's not the point. At the time, only research institutes
and universities had the need to disseminate information *and*
the hardware to do so, creating a fertile environment to
build fancy software to make it practical, fun, even. Neither
the military, nor any commercial enterprise would have made
this freely available, but CERN did, thus spawning the
explosive expansion of ubiquitous networking we have witnessed.
[On DC transformers] Hall effect is not from research at
CERN I think.

I was referring to DCCTs, invented by Klaus Unser in 1969.
He was at CERN at the time.
cryogenics, super conductivity, Kamerling Onnes was there first,

Yes, but again, that's not the point. CERN's massive use of
that technology makes it more accessible for the rest of us,
because it provides the impetus to develop cost-effective
and innovative solutions to technical problems.

When Ampere and Faraday played around with electricity, no-one
could have guessed what use we might make of it two centuries
later. It's like that with basic research: It looks pointless
at the time it's done, but a few decennia later it may change
the face of the world. That's what makes it worthwhile.

If I may slightly misquote Arthur Clarke, or was that Mark
Twain: "If we had had no research in the stone age, we might
have had superb flint axes, but no one would have invented
steel".

Jeroen Belleman
 
M

Martin Brown

Jan 1, 1970
0
Jan said:
CERN is a joke.
[The WWW] has nothing to do with the 'goal' (if any) that
CERN had or has.
And internet comes from a mil source.

That's not the point. At the time, only research institutes
and universities had the need to disseminate information *and*
the hardware to do so, creating a fertile environment to
build fancy software to make it practical, fun, even. Neither
the military, nor any commercial enterprise would have made
this freely available, but CERN did, thus spawning the
explosive expansion of ubiquitous networking we have witnessed.
[On DC transformers] Hall effect is not from research at
CERN I think.

I was referring to DCCTs, invented by Klaus Unser in 1969.
He was at CERN at the time.

OK, never met him.
I presume you are referring to the zero flux DCCT
(fluxgate with feedback for all I know).

Yes, but again, that's not the point. CERN's massive use of
that technology makes it more accessible for the rest of us,
because it provides the impetus to develop cost-effective
and innovative solutions to technical problems.

This is over simplified.
Sure you need research, as you point out.
But it is the market forces that push these,
even CERN is financed by taxes from profits in the markets.

No it isn't. It is scientists curiosity about nature that gets the big
breakthroughs. We would never have had lasers if it had been left to
beancounters and market forces. When they were first invented the price
was ludicrous and required large near perfect ruby crystals and huge
flash guns. Now every CD and DVD has one inside as do laser printers.

You can never predict where blue sky research will find applications.
These market forces and the research BY COMPANIES
(IBM researchers found the high temperature superconductors),
is what pushes to ever better solutions.

They were looking for better piezoelectric materials at the time. Same
with 3M and post-its the new glue was supposed to be super strong but it
turned out to have other useful properties. It could easily have been
killed at birth if the inventor had not found it a niche.
That is why the USSR was behind, no push from market forces.

Do you not remember Spudnik and Yuri Gugarin? Incidentally this year is
the 40th anniversary of the first man in space.
As to that 'www thing', the only 'invention' was the 'hyperlink'.

The hyperlink was invented in 1968.

The invention was the synthesis of global URL descriptors and a self
consistent text based way of specifying hyperlinks and content in a
graphical form. ISTR the Apple Mac help system was an influence on the
early web and that dates back to the mid 80's. Tim Berners-Lee put it
all together on the Internet and the rest is history. It was a genuine
spin-off from CERN no matter how much you may dislike the fact.

His intent was to make it easier for researchers to exchange data.
Handling the huge datasets from HEP has also spawned developments in
mapmaking - descendants of the same hardware that used to digitise HEP
film records in the 80's went on to digitise all the worlds maps.
Sure the C parser code was available for free from the CERN site, I downloaded it
and had a good look at it when I wrote this newsreader (it has some html parsing,
see the headers), many many years ago.
But from there it was pushed by the commercialisation of the web.
We had gopher, ftp, etc, what not.

ftp and gopher all predate the www. Most bulk transfers in those days
were done overnight as batch jobs to avoid upsetting daytime users.
Right, basic research is OK, but it should stay sane, and in proportion to results.

How can you possibly know in advance what the results will be? The whole
purpose of doing fundamental research is to find out something new that
is presently unknown or test the predictions of theory.
CERN and ITER are out of proportion, and have no results.

They do have plenty of results of interest to high energy physicists and
cosmologists. And the spin-off technology of synchrotron sources with
beam wigglers are now being used to power the coherent UV sources for
the next generation of chip making.

If you want to scrap something then the ISS is a pretty good candidate.
It is completely useless as a telescope platform and the "science" being
done in it would not look out of place at a school science fair.
That failed, all we got was brain dead parrots who parrot Einstein's equations
and write tissue paper about string quartets and wormholes.

Why is it that every nutter on the planet who cannot understand the
physics insists vehemently that Einstein was wrong?
I have nobody to quote but myself.
Scrap CERN, ITER, LIGO.

Just because you don't understand physics is no reason to scrap them.
If you cannot do it with those small particles (fusion power) on the desktop,
then you cannot do it in a machine the size of the universe (or city).

:)

Have you ever noticed that the sun seems to manage to sustain a pretty
reliable thermonuclear reaction. Astrophysics can put a pretty good
bound on the minimum mass needed to have a star light up about
75xJupiters - at least sufficient to burn off the lighter easy isotopes.
Such Brown Dwarfs (no relation) are observed by astronomers.

http://www.eso.org/public/news/eso0303/

Regards,
Martin Brown
 
J

Jeroen Belleman

Jan 1, 1970
0
Jan said:
Jan said:
CERN is a joke.
[On DC transformers] Hall effect is not from research at
CERN I think.
I was referring to DCCTs, invented by Klaus Unser in 1969.
He was at CERN at the time.

OK, never met him.
I presume you are referring to the zero flux DCCT
(fluxgate with feedback for all I know).

Yes, exactly.
Yes, but again, that's not the point. CERN's massive use of
that technology makes it more accessible for the rest of us,
because it provides the impetus to develop cost-effective
and innovative solutions to technical problems.

This is over simplified.
Sure you need research, as you point out.
But it is the market forces that push these,
even CERN is financed by taxes from profits in the markets.
These market forces and the research BY COMPANIES [...]

That's too simple. Sometimes we develop something and ask
industry to build it for us. Or we may buy something ready-
made. But often, for exotic technologies, it's some of both
in varying proportions. That's where it gets interesting,
because those technologies will then no longer be so exotic.
As to that 'www thing', the only 'invention' was the 'hyperlink'.
[...]
But from there it was pushed by the commercialisation of the web.
We had gopher, ftp, etc, what not.

Yes, that what I've been trying to say: Research invents
something, and then commerce takes over to make money from
it. That's the way it works, and that's the way it should be.
Right, basic research is OK, but it should stay sane, and in proportion to results.
[...]

You are quite right. However, the right proportion is much a
matter of opinion. The Netherlands' contribution of about
50 MSfr/yr is pittance, compared to the total state's budget
of some 250 GEuros. For better or worse, our political leaders
still seem to believe that CERN is useful, although their
motives may be quite different from ours.

Jeroen Belleman
 
M

Martin Brown

Jan 1, 1970
0
Ah, that's an interesting story...

Neither US no Russia were planning on launching a spacecraft.

USSR developed the H-bomb of the layered cake concept, which was much
heavier then the competing Ulaf-Teller design of the US. However, it
took several years for the US to make a real weapon of this concept;
whereas the simple "layered cake" bomb was already available to Russia.

High yield but with an inaccurate and not available delivery system via
ICBM. It would still do a lot of damage to large city targets though.
So, the russian military set the design goal of the ICBM with the throw
weight of ~5 tonns. That was a difficult problem for those days. The
development of the R-7 missile was a disaster; many crashes; they could
hardly hit a target of 100x100km size. The government and the military
started growling; there were talks on firing the management of the
project or pulling the plug at all. One of the designers suggested to
launch an object to the orbit, just to keep the government happy. So
they did. No one could expect that would raise such a tremendous public
response! Especially as the second stage of the ICBM flying in the orbit
could be seen with the naked eye (the actual payload "Sputnik" was too
small to be seen).Few yeas later, the modification of the same R-7 ICBM
was used to launch man in space.
//----------------

That explains why some folk insist that they saw Sputnik naked eye
despite that fact that it was too small to see without optical aid. The
second stage would have been a lot bigger and bright enough that the
people who think they saw Sputnik actually saw that.

A tiny group at a UK school and Jodrell Bank detected the unusual
signals from our first ever artificial satellite.

http://www.zarya.info/Kettering/Kettering.php

Sputnik's launch actually got the debts and delays of Jodrell Bank's
construction completely written off as another side effect. It was in
real danger of being cancelled for over budget and late. Suddenly it was
relevant in a way nobody has forseen. It subsequently eavesdropped on a
lot of Russian interplanetary probe telemetry famously resulting in the
first pictures from Venus appearing in the British press.
So, the "Sputnik" and Yuri Gagarin were the unexpected side effects of
the heavy ICBM development as opposed to the fundamental scientific
recearch with the goal to put a man in space.

Some times serendipity works in our favour.

Regards,
Martin Brown
 
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