Rigol oscilloscope prices have sky-rocketed!
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From: VWWall on 4 Jan 2010 21:26 Mr.T wrote: > <miso(a)sushi.com> wrote in message > news:8e1c962a-a471-448b-89b6-7239675017f0(a)k17g2000yqh.googlegroups.com... >> Surplus isolation transformers are pretty cheap. > > > Yeah when we had surplus stores here I got many big transformers that way. > They all (electronics surplus stores) disappeared years ago unfortunately. > 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.
From: Phil Allison on 4 Jan 2010 21:36 "VWWall" > You can make an isolation transformer that will handle a kilowatt from two > junked microwave oven transformers. ** No you cannot. > Just remove the HV windings and the magnetic shunt, leaving the primary > windings. ** Lunacy. > Connect them together with two coils wound on each core with a few turns > of No 12 insulated building wire. ** Complete insanity. > Calculate the number of turns to not exceed 20A at the intended maximum > load. ** VW is bullshitting wildly. No way has he tied it with success. The huge Imag figures of microwave oven transformers kills the wacky idea completely. ..... Phil
From: kreed on 4 Jan 2010 21:58 On Jan 5, 12:26 pm, VWWall <vw...(a)large.invalid> wrote: > Mr.T wrote: > > <m...(a)sushi.com> wrote in message > >news:8e1c962a-a471-448b-89b6-7239675017f0(a)k17g2000yqh.googlegroups.com.... > >> Surplus isolation transformers are pretty cheap. > > > Yeah when we had surplus stores here I got many big transformers that way. > > They all (electronics surplus stores) disappeared years ago unfortunately. > > 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. 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.
From: David L. Jones on 4 Jan 2010 22:48 miso(a)sushi.com wrote: > On Jan 4, 5:36 pm, "David L. Jones" <altz...(a)gmail.com> wrote: >> geoff wrote: >>> David L. Jones wrote: >> >>>> "Hello, Please don't worry, the problem is, an another seller has >>>> complaint by ebay that i'm selling the rigol oscilloscopes at a >>>> dumping price" He then offered to complete the original low price >>>> transaction >>>> outside of ebay. >> >>> Why should 'dumping prices' be a problem ? >> >> It shouldn't be a problem until a local official seller that can't >> possibly sell them for the same price complains. >> There are countless companies like (presumably) Rigol that have >> diferent wholesale pricing in different countries, so an official >> dealer in say Australia can't even buy it for less than what someone >> in China sells it for >> at a profit. Or to hold on to their dealership they aren't allowed >> to sell >> it under a certain price. >> With the advent of ebay and online trading, the world is a global >> marketplace, so these sorts of traditional regional pricing models >> make it a big fat mess. >> You can bet your bottom dollar the ebay sellers in China are (or >> were) not dumping the scopes at a loss, they made a very tidy profit. >> >> I have since heard that another Rigol seller also had their auctions >> banned >> for "dumping". So this appears to be the reason for removal of the >> hundreds >> of Rigol's that were for sale on Ebay. >> So it's likely that one (probably official Rigol) seller, that may >> not even sell on Ebay, spoiled all the fun by complaining. >> >> Dave. >> >> -- >> ================================================ >> Check out my Electronics Engineering Video Blog & >> Podcast:http://www.eevblog.com > > Dumping is selling beneath the cost of manufacturing, so only the > manufacturer can dump. A vendor can buy out the merchandise from a > store that goes out of business and sell those items for less than the > manufacturing cost. In the states, the FTC would have to declare a > dumping situation. [I haven't had to deal with the FTC in a long > time, but it was an amazingly accessible organization considering you > were dealing with the government. > > Like I've said, I need to see the documents on this alleged dumping. There almost certainly aren't any, it's an internal ebay decision. The seller probably just got an email informing them their listings have been removed because of a breach of some rule, and that's it, end of story. Some monkey at Ebay has spoken. > I just don't see Ebay taking sides in any kind of dispute like this. Ebay are judge, jury and executioner, and they are famous for showing it. Indeed, they have to be shown to take complaints of legal matters seriously, and they err on the side of caution every time. If they get any complaint with the wiff of a legal basis, they'll just pull the listing(s). Their site, their rules, they don't muck around, and the "victim" (sellers in this case) usually doesn't get any recourse. > Rather, I see Rigol deciding not to sell stock to certain vendors that > they don't like. Maybe, but there are many other ways to obtain them, esp in China, so that doesn't explain the lack of no more cheap Rigol scopes on Ebay. The only facts are that Ebay have removed the cheap Rigol listings for what they are calling "dumping". You can still buy the unit at the old cheap prices from various other online dealers, drop-shippers, and Chinese sources, here is but one example: http://www.aliexpress.com/wholesale?SearchText=rigol&CatId=0 Dave. -- ================================================ Check out my Electronics Engineering Video Blog & Podcast: http://www.eevblog.com
From: Mr.T on 5 Jan 2010 02:09
<miso(a)sushi.com> wrote in message news:23b6594d-3c71-45d0-885a-bb5cbf16ce1f(a)a32g2000yqm.googlegroups.com... >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. 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. |