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#25 Reply
Posted by
zlymex
on 22 Oct, 2016 14:17
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For those interested in the 2DW2xx, maybe zlymex can help out, since he has access to tabao and know's what could be real, we could buy them for the ones that want them, and send them out, if he want to get this kind of trouble. :-)
Yes. I can buy a batch and mail it to one oversea location at my own expense, and the one who receive the package will responsible for distribution to who ever needed and agreed in certain term.
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#26 Reply
Posted by
VintageNut
on 22 Oct, 2016 15:45
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Hello Zlymex
That would be a "group buy" as we say in the USA.
I am willing to host the logistics in the USA. I can receive the parts and send out the parts to the participants in the USA.
For myself, I do not require hundreds of parts. I only need 20 to 30 pcs of each of 2dW233, 2dw234.
Do the higher current parts have lower noise? For example does the 2DW234 have lower noise than the DW233? If so, is the 2DW236 the lowest noise part?
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#27 Reply
Posted by
Cerebus
on 22 Oct, 2016 16:53
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Is there any particular place in Europe that would be advantageous from a postal costs point of view to use as a hub for the European leg of this? I ask as I'm quite happy to volunteer as the hub of the European leg of this, but UK postal rates to other European countries have always traditionally been one of the higher.
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#28 Reply
Posted by
zlymex
on 23 Oct, 2016 04:51
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Ok. may be I will buy 200pcs(or more?) and mail them to VintageNut/USA, and VintageNut will mail 100pcs to Cerebus/Europe, or may be the other way round. I'll check which way is better(available postal, custom, pricing) tomorrow.
From my tests, 2DW232 or 2DW233 will do, the difference with others(2DW235, 2DW234) is only the nominal zero TC current, but I saw not very much actual difference, and the zero TC current of 2DW232 or 2DW233 are usually higher than nominal. The manufacture seems to mark the brand randomly.
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#29 Reply
Posted by
JS
on 23 Oct, 2016 05:17
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You do want zero TC, if it's at higher current it would usually be a good thing, as it means lower noise, unless you are after long term stability instead of low noise, in which case you wouldn't be using the 2DW233 I guess.
JS
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#30 Reply
Posted by
Kleinstein
on 23 Oct, 2016 09:09
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Even the 2DW233 has the zero TC at already quite a high current level and thus low noise. High currents also cause more self heating and thus require a higher temperature. So I don't think it really helps to go above 5 mA. If than one could still use 2 units in parallel for lower noise - usually 2 units at 5 mA should give a lower noise than 1 at 10 mA, not for the higher frequency part, but for the 1/f part. With the relatively low price it is a very real option to use 2 or even more refs combined.
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#31 Reply
Posted by
Nuno_pt
on 23 Oct, 2016 10:54
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This would be a good project to buy some 30 of the 2DW2xx, select 14 of them and make an stable 100V, but probably the PSU's would have to be separate for each, this could be better than buffering the LM399/LTZ to 100V.
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#32 Reply
Posted by
Theboel
on 23 Oct, 2016 11:33
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count me for 20pcs, EU or USA doesnt matter
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#33 Reply
Posted by
VintageNut
on 23 Oct, 2016 12:27
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Hello Zlymex
The lowest cost will be China Post to United States Postal Service.
I have bought several $20 items from eBay and AliExpress that incur no customs fee to the USA. There is ePacket China Post shipping which is used by eBay that is very low cost.
If you ship to UK or Eu first , there will probably be Value Added Tax.
If it is not too much trouble, maybe ship one package to USA and one package to UK?
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#34 Reply
Posted by
zlymex
on 23 Oct, 2016 13:36
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#35 Reply
Posted by
eliocor
on 23 Oct, 2016 13:45
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I would be interested in about 30/50 pieces...
I live in Europe (Italy)
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#36 Reply
Posted by
Nuno_pt
on 23 Oct, 2016 13:55
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If you ship to UK or Eu first , there will probably be Value Added Tax.
Here till 22€ we don't pay nothing, but if the package is small and the value is higher, and the declared value is low e.g. $5 there is no problem.
The prices here for the shipping for all EEC are 4€ till 500g, I can post here the shipping cost for the various weights.
If it is not too much trouble, maybe ship one package to USA and one package to UK?
That would be best, since from the US to EU, you can add another week at least.
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#37 Reply
Posted by
pmcouto
on 23 Oct, 2016 14:01
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I would be interested in about 50 pcs.
Regards,
Pedro
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#38 Reply
Posted by
Squantor
on 23 Oct, 2016 14:48
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I would be interested in 20 pieces or more depending on pricing. I live in the Netherlands.
I have actually ordered a bunch from aliexpress. Hopefully they are diamond brand but I don't count on it.
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#39 Reply
Posted by
JS
on 23 Oct, 2016 15:08
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This would be a good project to buy some 30 of the 2DW2xx, select 14 of them and make an stable 100V, but probably the PSU's would have to be separate for each, this could be better than buffering the LM399/LTZ to 100V.
You could do it with a single supply, provided you find the zero TC current for all the devices together.
Even the 2DW233 has the zero TC at already quite a high current level and thus low noise. High currents also cause more self heating and thus require a higher temperature. So I don't think it really helps to go above 5 mA. If than one could still use 2 units in parallel for lower noise - usually 2 units at 5 mA should give a lower noise than 1 at 10 mA, not for the higher frequency part, but for the 1/f part. With the relatively low price it is a very real option to use 2 or even more refs combined.
Ok, when you said require a higher temp are you talking about an oven or just that it will go higher? I should double check the levels, I didn't know it was already that high.
JS
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#40 Reply
Posted by
VintageNut
on 23 Oct, 2016 16:16
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Ok, the item I plan to buy is here: https://item.taobao.com/item.htm?spm=a230r.1.14.17.q4TxU1&id=35862405041
I've already bought from the entry before and proofed to be genuine(low noised). I've just online talked to the seller that they still have the same batch as I bought for at least 300pcs, which is dated 14-4.
Hello Zlymex
If you buy 300 pcs, you can ship 150 pcs to USA and 150 pcs to Eu. I can handle sending out envelopes from USA.
My thought is to make 25 pcs available to 5 people from the USA. I will keep 25 pcs for my project(s).
The seller's price at Taobao looks like USD $0.25 each so the 150 pcs will be USD $37.50 plus shipping to Zlymex in China and shipping from China to USA and any customs that the US Customs charges. We shall see.
Zlymex, I can send you payment from Paypal if you want. Just let me know. There is no hurry for me.
My intention is to make one "group reference". Sort of a poor man's bank of Fluke 732B. It would be good to find a way to make an ovenized PCB that can be kept at 30 deg C or maybe even a little higher.
Thank you for sharing your China low noise zener source!
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#41 Reply
Posted by
pelule
on 23 Oct, 2016 16:53
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I would have interest in 30 pieces for me as one of the European batch receivers.
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#42 Reply
Posted by
MatteoX
on 23 Oct, 2016 17:23
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Hi, I would also be interested for 25 pcs or more for the USA group buy.
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#43 Reply
Posted by
Cerebus
on 23 Oct, 2016 17:29
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The prices here for the shipping for all EEC are 4€ till 500g, I can post here the shipping cost for the various weights.
As I suspected, that rules out the UK as the European hub. The cheapest from here to Portugal for 250-500g is over £5 GBP - even with the low £ that's still nearly 50% higher shipping costs.
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#44 Reply
Posted by
Nuno_pt
on 23 Oct, 2016 17:55
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We've also the express mail, that is from 100g - 250g = 4.70€ and from 250g - 500g = 6.40€ for EU.
The normal mail is 100g - 250g = 2.35€ and from from 250g - 500g = 4€ for EU.
And 0.65€ for an bubble bag, so if the 25x 2DW23x are from 100g - 250g, that will be 2.35€ + 0.65€ = 3.00€ + 23% VAT = 3.69€ if my math is correct, and I'm looking at this the correct way.
Let's see how many are need for EU & US.
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#45 Reply
Posted by
Cerebus
on 23 Oct, 2016 18:28
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We've also the express mail, that is from 100g - 250g = 4.70€ and from 250g - 500g = 6.40€ for EU.
The normal mail is 100g - 250g = 2.35€ and from from 250g - 500g = 4€ for EU.
And 0.65€ for an bubble bag, so if the 25x 2DW23x are from 100g - 250g, that will be 2.35€ + 0.65€ = 3.00€ + 23% VAT = 3.69€ if my math is correct, and I'm looking at this the correct way.
Let's see how many are need for EU & US.
The nearest part, mechanically, I have here is in a TO-72 case and that weighs in at 0.91gm. So 25 off would be in the close region of 25gm + the weight of packaging.
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#46 Reply
Posted by
Nuno_pt
on 23 Oct, 2016 18:34
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Ok so new prices for normal mail;
20g - 50g = 1.20€
50g - 100g = 1.40€
For express mail;
20g - 50g = 3.10€
50g - 100g = 3.60€
Plus the above package and VAT.
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#47 Reply
Posted by
orin
on 23 Oct, 2016 19:39
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Count me in for 20 in the USA.
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#48 Reply
Posted by
branadic
on 23 Oct, 2016 20:38
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I'm interested in 30 pieces too. Germany/Europe
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#49 Reply
Posted by
hammy
on 23 Oct, 2016 20:48
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I would also be interested for 30 pcs for the EU/Germany group buy.
Thank you!