Rigol oscilloscope prices have sky-rocketed! - Page 2

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Re: Rigol oscilloscope prices have sky-rocketed!



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Yeah when we had surplus stores here I got many big transformers that way.
They all (electronics surplus stores) disappeared years ago unfortunately.

MrT.



Re: Rigol oscilloscope prices have sky-rocketed!


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I don't know where "here" is for you, but in the SF Bay Area, so much
manufacturing has left the area that the surplus stores are struggling
to get surplus stuff. Throw ebay into the equation, and there is even
less stuff available in stores.  But isolation transformers are more
of a lab item than a production item, so they may still be in your
area locally, but probably stashed in some garage.

Topaz transformers show up from time to time at electronics flea
markets. In the days when  small company owned a Vax, the Topaz was
your isolation transformer.

Re: Rigol oscilloscope prices have sky-rocketed!



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Yep, had a Topaz myself once, but I've never seen one going cheap in
Australia! Not to say it can't happen, but you'd have to be very lucky, not
something the OP can necessarily go and buy at a reasonable price just
because he wants it. And not something you'd want to carry in your car
either, to use with an inverter supply!

MrT.



Re: Rigol oscilloscope prices have sky-rocketed!


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Freight for a Topaz down under would be significant. Topaz has made
some units that are small, well small for a Topaz. Maybe 12x8x8
inches.

Re: Rigol oscilloscope prices have sky-rocketed!


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Ouch !  That is one hell of a transformer :)

Re: Rigol oscilloscope prices have sky-rocketed!



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Naw, at operating frequency of 50/60 Hz that is only about 2000 VA.

Re: Rigol oscilloscope prices have sky-rocketed!


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You can make an isolation transformer that will handle a kilowatt from
two junked microwave oven transformers.  Just remove the HV windings and
the magnetic shunt, leaving the primary windings.  Connect them together
with two coils wound on each core with a few turns of No 12 insulated
building wire.  Calculate the number of turns to not exceed 20A at the
intended maximum load.

--
Virg Wall, P.E.

Re: Rigol oscilloscope prices have sky-rocketed!


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This sounds very bodgy to me.


Getting 2 identical transformers, and putting the 2 primary windings
on one core would be a better idea
This would involve taking them (the E and I parts) apart and putting
them back together - not easy for the inexperienced.


Whether in practice it would work well is another matter.

Re: Rigol oscilloscope prices have sky-rocketed!



viestissä:wN6dnWD6k6DfPt_WnZ2dnUVZ_ snipped-for-privacy@earthlink.com...
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Would it work if I just connect HV windings together?
So as to avoid any rewounding job.
-ek



Re: Rigol oscilloscope prices have sky-rocketed!


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If you have to do it - try using a pair of 240 - 110v / 48v / 24v
units back to back or other matching voltage low voltage surplus
transformers.

I did this 25 odd years back using  2 surplus (free)  240v to 24v @15a
units back to back, and it worked fine for many years.  It wont be as
efficient as a single purpose designed transformer, and will be
heavier and run hotter.

Remembering that there will be 2 lots of losses, and that normal
transformers aren't designed to be used "backwards", you will NOT get
the full rated VA out of this arrangement, it will cost more in
electricity use.



I wouldn't even contemplate that idea of putting microwave HT windings
back to back - it would be an absolutely totally and instantly LETHAL
device if anything went wrong, not just an irritating "ZAP".
Please, Please Please do NOT muck about with these things. these
voltages (remember that unlike TV EHT supplies these oven transformers
have plenty of current behind them) can even punch through damaged or
underrated insulated tool handles and to your hand, delivering a
lethal shock !


If there was a breakdown to the output winding, which could possibly
happen with old parts - specially ones from faulty microwaves pulled
from rubbish dumps, or that had mouse / insect infestations  - I would
hate to think what could possibly happen to anyone or anything
connected on the 240v isolated "secondary" side.

If you didnt join the 2 HT windings together in a proper way, and
insulate properly the connection point could even arc, starting a
fire.



Either physically remove the HT winding first if you are going to muck
around with it, or better still, just do yourself a favour and chuck
the microwave oven transformer (and the modification idea) in the
rubbish bin before someone gets killed.





Re: Rigol oscilloscope prices have sky-rocketed!



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Not that i recommend that inexperienced persons try such, i do not.
Just the same, while i recognize the potential problems, i have no20%
unreasoning fear of them.  Nor am i such a nanny type as to insist20%
on trying to prevent anyone from doing something odd but useful.

Thus i find you to be quite an obnoxious prunt.

Re: Rigol oscilloscope prices have sky-rocketed!


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It will certainly make it very noisy




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Re: Rigol oscilloscope prices have sky-rocketed!


On Sat, 2 Jan 2010 21:34:25 -0800 (PST), the renowned " snipped-for-privacy@sushi.com"

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Pretty much. eBay is a profit-oriented corporation and doesn't have to
allow any particular person to be a customer. They will concentrate on
satisfying the big sellers who bring them big money, and the big IP
owners (and the government) who can cause them big problems. Telling
some troublesome small seller to go away is a low-cost way of avoiding
problems.

http://pages.ebay.com/help/policies/items-ov.html

There is no specific eBay restriction on radio scanners that I can
see. I'm not sure the prohibition has ever been applied to private
importation for personal use. Here's the relevant law-- they slipped
it into the back (Sec 403) of a bill mostly aimed at regulating the
1-900 bandits.

http://www.fcc.gov/Bureaus/OSEC/library/legislative_histories/1460.pdf

It's been years since I've even seen an analog phone anyway, so it's
kind of a non-issue these days.

Hmmm...

http://www.fcc.gov/Forms/Form740/740.pdf

Exemption:

7. Three or fewer radio receivers, computers, or other unintentional
radiators as defined in Part 15 of the FCC Rules, are being imported
for an individual’s personal use and are not intended for sale.

So it doesn't look like there is any prohibition on importing a few
for private use, provided you fill out the proper paperwork (not that
you'd likely be asked if USPS handled it) and you are what the US Feds
call the _importer of record_.

BTW, Disney regularly complained and had auctions terminated of items
made from legitimate licenced Disney fabric. They seem to have backed
off recently, but only because the sellers spent the money and time to
take Disney to court directly.

http://pages.ebay.com/help/community/NOCI1.pdf

Here we are talking about grey-market goods. Since the mfg company
generally owns the trademark, it has a say over what eBay allows--
even if the sales are legally allowed. Mfrs like to have the freedom
to maintain separate distribution networks- for example, a product
sold in the US may be cheaper than one sold through a distributor in
Canada. And it may be cheaper again in China, but perhaps no warranty
is provided (and maybe quality control isn't as good or accessories
are not as complete). If they don't limit grey market sales, local
disties won't have enough margin to survive and service (and their
brand name) will suffer. It's a legitimate concern, but also in
restraint of trade (seems to be allowable in the US, judging by car
dealers). In the US this is sort of an IP issue, and it could be a
contractual issue with offshore distributors (eg. no sales allowed
outside of your geographic area or we cut you off). Pretty hard to
enforce in some cases:

http://www.managingip.com/Article/2040839/Combat-grey-market-goods-in-the-US.html




Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
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Re: Rigol oscilloscope prices have sky-rocketed!


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I also had something similar. I was unable to see a product listed on
ebay a guy sent me a link to with my original IP address (located in
Bulgaria); had to hide behind some proxy to be able to see it (the
guy just wanted me to comment on the thing, was some sort of power
supply).

To believe all the "just market forces" cliche we are bombarded with
every day (anything else being branded "conspiracy theory") is just
naive nowadays. It is more like "just Darwinian forces", which is not
the same.

Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com http://tgi-sci.com/tgi/nmcatb.htm <---- new
------------------------------------------------------
http://www.flickr.com/photos/didi_tgi/sets/72157600228621276 /

Original message: http://groups.google.com/group/sci.electronics.design/msg =
/c9668797d9771905?dmode3D%source

Re: Rigol oscilloscope prices have sky-rocketed!



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I pay zero dollars for my American Express card(s).  No
_direct_ fees, at least, annual or otherwise.  I'm sure
businesses I buy from make certain they make a profit,
though.  So I'm probably paying for it when I buy anything at
all from a sales outlet that so much as accepts the card. I'm
probably paying for other cards, too, whether or not I care
to use them.  It all comes out in the wash.  (Speaking of
which, what is the German equivalent for that last idiom?)

Jon

Re: Rigol oscilloscope prices have sky-rocketed!


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Mostly they use a slang expression: "Es ist Pott wie Deckel". Pretty
much not-translateable :-)

--
Regards, Joerg

http://www.analogconsultants.com /

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Re: Rigol oscilloscope prices have sky-rocketed!



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The closest translation i can propose is "cover the whole pot".

Re: Rigol oscilloscope prices have sky-rocketed!


On Thu, 07 Jan 2010 23:48:00 -0800,

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I think the terms Pott and Deckel are used together in German
more like "made for one another" is in Engish.  Something
like "wie Pott und Deckel" to mean "well-suited for each
other."  So 'wie' here is more like the English word "as" or
"alike" than the denoted translation into "how."

The phase "Pott wie Deckel" then looks to me more like some
kind of "all the same as" phrase.  So the result is then more
like "it is all the same as."  As I read it, anyway.  And
thanks very much, Jörg, for the idiom!

This is the kind of thing I could _never_ produce on my own,
lacking experience.  But when I _read_ it from someone else
like Jörg writing it, I can dredge up some past training
about it and seem to gather it.  I can read German rather
somewhat more fluently than I can produce the darned stuff! I
sure wish I had someone local to train with.  I wonder if
Jörg needs a personal butler for a while!  ;)

Jon

Re: Rigol oscilloscope prices have sky-rocketed!



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I should have added some English examples that illustrate how
Pott and Deckel are, when used in "wie Pott und Deckel":

  -  like Horse and Carriage
  -  like peas in a pod
  -  hand and glove

Jon

Re: Rigol oscilloscope prices have sky-rocketed!


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Yep, exactly.



There are many more and which one is used depends on the region. For
example, in Bavaria they'd say "gehupft wie gesprungen".


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That's the only way to learn it, either in the country or in a group of
people where you are sort of forced to speak it and the exposure to
other languages is zero for hours at a time. This is how I learned Dutch
but now it has degraded to where I can read and understand. Writing has
become horrible and speaking usually comes back after 2-3 beers.


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No, but a brewmaster :-)

Some day I'll brew again. But tonight we'll first bake bread on the
barbecue. Yummy!

--
Regards, Joerg

http://www.analogconsultants.com /

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