Author Topic: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x  (Read 130175 times)

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Offline Nuno_pt

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #25 on: October 22, 2016, 11:03:46 pm »
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. :-)
Nuno
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Offline zlymex

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #26 on: October 23, 2016, 01:17:20 am »
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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Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #27 on: October 23, 2016, 02:45:28 am »
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?
working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 
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Offline Cerebus

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #28 on: October 23, 2016, 03:53:52 am »
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.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline zlymex

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #29 on: October 23, 2016, 03:51:24 pm »
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.
 

Offline JS

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #30 on: October 23, 2016, 04:17:50 pm »
  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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Online Kleinstein

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #31 on: October 23, 2016, 08:09:47 pm »
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.
 

Offline Nuno_pt

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #32 on: October 23, 2016, 09:54:42 pm »
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.
Nuno
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Offline Theboel

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #33 on: October 23, 2016, 10:33:34 pm »
count me for 20pcs, EU or USA doesnt matter  8)
 

Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #34 on: October 23, 2016, 11:27:31 pm »
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?
working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 

Offline zlymex

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #35 on: October 24, 2016, 12:36:15 am »
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.
 

Online eliocor

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #36 on: October 24, 2016, 12:45:09 am »
I would be interested in about 30/50 pieces...
I live in Europe (Italy)
« Last Edit: October 24, 2016, 01:19:59 am by eliocor »
 

Offline Nuno_pt

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #37 on: October 24, 2016, 12:55:12 am »
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.

Nuno
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Offline evb149

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #38 on: October 24, 2016, 12:58:39 am »
Hi, I would be interested in some in the USA.  Somewhere in the 25-250 range I suppose depending on what the overall pricing looks like.

EDIT: Hi zlymex, thank you for all of the good information you have shared about these models of references as well as noise measurement circuits, and for being willing to facilitate a group buy.
And thank you VintageNut, thank you for your interest to also facilitate a group buy.
I am wondering what the price discount versus quantity of parts purchsed is?  I think I saw that zlymex may have previously been buying hundreds of such parts, (550pcs, 200pcs,...) at once, and maybe that is at the best price per lot level or maybe it is better at some other possible level that is achievable in the group purchase?

Also I apologize for the basic question but I wonder if from the research you all have done if there is any indication as to the likely magnitude of the long term drift of these devices, and also the unit to unit variation of characteristics in a batch, and whether some factors like humidity change, mechanical stress, or vibration would likely be a significant concern in integrating these into a circuit?

In response to VintageNut's comment about a temperature controller, as well as to generalize about making some open HW that could be useful to the users of this part, I would be glad (*as long as I can spare any time in the coming days/weeks) to contribute my effort to design a temperature controller or other accessory PCB / circuit design for this sort of purpose. 

I do not have access to any especially good temperature measurement hardware (beyond basic NTC thermistors, a couple of IC digital sensors, some K thermocouples, and 2N3904 junctions that could be measured), and not at all any premade environmental controlled test / calibration system, though, but I could make a custom firmware + data acquisition based controller design and come up with some ideas for use of either printed foil heaters, discrete resistor heaters, or similar simple concepts.  I suppose that should easily be enough to look for non-absolute temperature correlated short term variations in particular spots of maybe under 0.1C.  I might be able to get a basic RTD to look for smaller fluctuations and have something more closely correlated to absolute temperature.

 
« Last Edit: October 24, 2016, 05:12:40 am by evb149 »
 

Offline pmcouto

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #39 on: October 24, 2016, 01:01:24 am »
I would be interested in about 50 pcs.

Regards,
Pedro
 

Offline Squantor

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #40 on: October 24, 2016, 01:48:46 am »
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.
 

Offline JS

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #41 on: October 24, 2016, 02:08:46 am »
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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Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #42 on: October 24, 2016, 03:16:13 am »
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!
working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 

Online pelule

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #43 on: October 24, 2016, 03:53:02 am »
I would have interest in 30 pieces for me as one of the European batch receivers.
You will learn something new every single day
 

Offline MatteoX

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #44 on: October 24, 2016, 04:23:30 am »
Hi, I would also be interested for 25 pcs or more for the USA group buy.
 

Offline Cerebus

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #45 on: October 24, 2016, 04:29:42 am »

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.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline Nuno_pt

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #46 on: October 24, 2016, 04:55:23 am »
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.
Nuno
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Offline Cerebus

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #47 on: October 24, 2016, 05:28:46 am »
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.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline Nuno_pt

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #48 on: October 24, 2016, 05:34:28 am »
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.

Nuno
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Offline evb149

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #49 on: October 24, 2016, 06:25:37 am »
From the picture it looks like these may (just a guess since they could just be side by side die) be monolithic.
Does anyone know from a tear down or thermal analysis if this is one monolitic die, or two physicaly different die side by side?

Has anyone done a thermal analysis to see what the temperature coupling response is from one zener to the next?

If they are either monolithic or side by side independent die but likely from the same wafer I wonder how good the parametric matching is from one zener to the next in the same package?
 
It seems like one could
(a) make a dual reference of course + and - 6.xV
(b) use the second zener as a forward biased diode junction temperature sensor  to sense temperature of the other zener (as has been mentioned here)
(c) maybe use one zener with a variable curent through it as a heater to heat the adjacent unit and help control its temperature over a small range (and perhaps also as a temperature sensor).
 


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