Author Topic: Group buy: LTZ1000 precision resistor set  (Read 13880 times)

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Offline dkozel

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Re: Group buy: LTZ1000 precision resistor set
« Reply #25 on: October 09, 2018, 04:17:07 pm »
Is everyone going for ±0.1%, ±3 PPM/°C maximum resistors or is anyone specifying higher tolerances for some/all of the resistors?

Based on these results it looks like improving the tempco of R4/5 and R2 (and the 10V output divider if used) is useful for the output stability.
https://github.com/pepaslabs/ltz1000-info
 

Offline dkozel

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Re: Group buy: LTZ1000 precision resistor set
« Reply #26 on: October 10, 2018, 01:51:43 pm »
I ended up going for ±0.1%, ±3 PPM/°C for everything except the output divider which is ±0.01% mostly for vanity sake.

I was tempted to get lower tempco R4/5 resistors, but tbh I'm too newbish with voltnutting for that to be worthwhile. Once I can measure the end tempco of the whole reference then maybe I'll upgrade them. Or try to match the three sets I have as close as possible... Sounds like a great way to never actually build the whole circuit. :D

Thanks MiDi for organizing this buy, it's pushed me to actually go forward with it!
 

Offline meandeev

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Re: Group buy: LTZ1000 precision resistor set
« Reply #27 on: October 10, 2018, 07:48:12 pm »
it was the last line of the "quote of pm" in the first post.

I copied the address from the first post.
@MiDi: was this intended (to block e-mail grabbers)?

Where did you got it? Do not see it.
In the announcement is the linked mail, no c&p needed.
 

Offline pansku

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Re: Group buy: LTZ1000 precision resistor set
« Reply #28 on: October 15, 2018, 10:39:52 am »
So what is the "standard" resistor configuration most of you ordered, is it the one from the first post for non-A configuration (12,5k or 13k?) and the two for the 10V stage?

Edit: With the size, tempco's and tolerances from the same post?
« Last Edit: October 15, 2018, 10:44:43 am by pansku »
 

Offline MiDiTopic starter

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Re: Group buy: LTZ1000 precision resistor set
« Reply #29 on: October 15, 2018, 01:17:24 pm »
Standard would be Datasheet values - 13k for ~60°C set point.

I went for 12k for non A and 12.5k for A as I want to use both at low temp.

For 10V boost went for 5k & 12/12.5k with same specs for tests.

If you want precise 10V output you would order individual values for specific LTZ1000 with tighter tolerance.
« Last Edit: October 15, 2018, 02:41:59 pm by MiDi »
 
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Offline BradC

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Re: Group buy: LTZ1000 precision resistor set
« Reply #30 on: October 15, 2018, 01:52:27 pm »
So what is the "standard" resistor configuration most of you ordered, is it the one from the first post for non-A configuration (12,5k or 13k?) and the two for the 10V stage?

Edit: With the size, tempco's and tolerances from the same post?

I haven't ordered any boost resistors. I've gone with 4 standard LTZ sets. 3 with 13k and 1 with 12.5k. Reading Edwins posts he specs his resistors at 3ppm as that appears to be the worst possible case (short of damage). If you wanted anything specifically tighter I suspect then you're into testing and selection and that might get expensive, although prices I've seen bandied about even for unrealistically tight tolerances seem to be pretty damn reasonable. I plan on testing 4 sets to figure out which parts track the best for a single "best" set with the 12.5k resistor. It feels a bit like bike-shedding, but what they hey.

Anyway, some Sfernice resistors arrived today so when the boards get here I have 2 I can assemble while I wait for the Ultrohm Plus units to arrive (I ordered mine a couple of weeks ago, before the *special* offer so hopefully I'm ahead on the production queue). I have KX boards due in the next day or so, and the boards from branadic should be here in the next couple of weeks.

 

Offline pansku

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Re: Group buy: LTZ1000 precision resistor set
« Reply #31 on: October 15, 2018, 04:22:12 pm »
Standard would be Datasheet values - 13k for ~60°C set point.

I went for 12k for non A and 12.5k for A as I want to use both at low temp.

For 10V boost went for 5k & 12/12.5k with same specs for tests.

If you want precise 10V output you would order individual values for specific LTZ1000 with tighter tolerance.

Thanks, I just sent the email. I'll be building 2 boards with these and for the third I'll try and get some VHP-parts through work for my "absolute" 10V reference and have that characterized by the cal lab from work (1 step down from NMI) with their 8508 when there is a free time slot :popcorn:

There are so many pages of the LTZ-thread, can any of you remember some pages where they talk about aging the references in heat. I might have access to a weather cabinet at work which goes from -20c to 140c for the holiday season, fingers crossed  ;D
 

Offline MiDiTopic starter

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Re: Group buy: LTZ1000 precision resistor set
« Reply #32 on: October 15, 2018, 07:14:09 pm »
Look at the last posts, you might not want to do that after reading -> hysteresis.
 

Offline blackdog

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Re: Group buy: LTZ1000 precision resistor set
« Reply #33 on: October 17, 2018, 11:31:31 am »
Hi,

For a number of years now I have two LTZ1000AHC reference ICs on the shelf.
I want to use them now and who do I order the resistors from... the topics are still a bit unclear.
is there still a joint buying action or should I order it from Edwin before October 21?

I would also like to have resistors to go from 7V to 10V.
Yes I know that the preciece values vary per IC.

Thanks for the help and kind regards,
Bram
Necessity is not an established fact, but an interpretation.
 

Offline MiDiTopic starter

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Re: Group buy: LTZ1000 precision resistor set
« Reply #34 on: October 17, 2018, 02:15:08 pm »
I want to use them now and who do I order the resistors from... the topics are still a bit unclear.
is there still a joint buying action or should I order it from Edwin before October 21?

I would also like to have resistors to go from 7V to 10V.
Yes I know that the preciece values vary per IC.

As most went for the Ultrohm Plus PWW from Edwin, you could go with them and participate from special offer till October 21.
In first post there are details given from Edwin, also regarding boost 7V->10V dividers.
Finally you have to make your own decision...

For other manufacturers there is currently no joint buying, but feel free to organize one  ;)
 

Offline MiDiTopic starter

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Re: Group buy: LTZ1000 precision resistor set
« Reply #35 on: October 19, 2018, 05:39:19 pm »
Last call for special offer
 
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Offline quarks

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Re: Group buy: LTZ1000 precision resistor set
« Reply #36 on: October 20, 2018, 03:49:24 pm »
Last call for special offer

thanks for the reminder allmost missed it
 

Offline MiDiTopic starter

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Re: Group buy: LTZ1000 precision resistor set
« Reply #37 on: October 29, 2018, 06:08:55 pm »
Just short update on Halloween special from Edwin:

Quote
I have started sending out final pricing, you are in the second batch which will go out very soon.  Response was well beyond what I was expecting; the ‘paperwork’ is eating up a lot of time.  The first batch of resistors will be going out soon and I have started prepping for the second batch.

So for those that did not receive final pricing yet, Edwin is very busy with our orders and we will receive it soon  ;)
 

Offline Edwin G. Pettis

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Re: Group buy: LTZ1000 precision resistor set
« Reply #38 on: October 30, 2018, 01:21:40 am »
I've had an inquiry about the final pricing, so to hopefully prevent a bunch of e-mails:

After I announced the base price and discount, the orders kept coming in, necessitating a restocking of some inventory.  I have been running on inventory I bought awhile back, since then the supplier has raised prices significantly (over 100%).  Since I didn’t want to hit a significant number of later ‘Halloween’ customers with a large increase, I took a minimal amount averaged into all of the parts which did bring the discount down a little, without it; it would have been closer to 9% or less.  I had not increased my pricing while I was running off of the old inventory knowing that someday I would have to restock and get stung by the higher prices.  There is no way around it.  Once this ‘NOS’ inventory is gone I will have to bump up prices to cover the increase and I won’t be able to soften the hit like I did now.  The pricing is still at the 100+ price discount even with the small hike.  According to my research, my pricing is still lower than Rhopoint’s  or NEOHM's 100 piece pricing.
 
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Offline julianhigginson

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Re: Group buy: LTZ1000 precision resistor set
« Reply #39 on: October 30, 2018, 04:58:04 am »

That's a shock to have your costs go up so much. thanks for trying to do what you can with it.

Looking forward to getting my order whenever it's able to be done.
 

Offline MiDiTopic starter

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Re: Group buy: LTZ1000 precision resistor set
« Reply #40 on: November 02, 2018, 07:50:10 am »
Everyone who ordered on Halloween special from Edwin should have received the final pricing, if not: please contact Edwin.
 

Offline julianhigginson

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Re: Group buy: LTZ1000 precision resistor set
« Reply #41 on: November 03, 2018, 01:58:28 am »
Everyone who ordered on Halloween special from Edwin should have received the final pricing, if not: please contact Edwin.

Edwin had told me not all quotes are sent out yet (mine wasn't when I read this post....) Apparently we will have him building resistors for quite some time. :-)
 

Offline BradC

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Re: Group buy: LTZ1000 precision resistor set
« Reply #42 on: November 03, 2018, 04:12:21 am »
Everyone who ordered on Halloween special from Edwin should have received the final pricing, if not: please contact Edwin.

Edwin had told me not all quotes are sent out yet (mine wasn't when I read this post....) Apparently we will have him building resistors for quite some time. :-)

That's what we call "a nice problem to have". I'm glad I got mine ordered a month ago.
 

Offline artag

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Re: Group buy: LTZ1000 precision resistor set [for branadic 10V pcb]
« Reply #43 on: November 04, 2018, 11:49:47 pm »

For some reason we don't have this with stuff imported from China. As a Brit I look forward to Brexit so we can drop this insane EU shit and import stuff as freely from the USA as we get with China.

Well .. except for EU countries. At the moment they're quick and cheap for the UK, and the bankers don't get much commission. Once we're out of the club, we'll have to deal with Germany the way the USA etc. does now - painfully. The USA will probably be the same as it is for us now, unless Trump throws a wobbly. So will the middle east, because the arms dealers don't want to pay too much tax. China should be the same, but one day HMRC will catch up with them and start taxing them to the rules. So .. I'm not sure where will be easier to deal with. Somewhere that isn't the far east, the far west, europe. And does electronics. Maybe Putinland ?
 

Offline julianhigginson

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Re: Group buy: LTZ1000 precision resistor set
« Reply #44 on: November 05, 2018, 12:57:50 am »

That's what we call "a nice problem to have". I'm glad I got mine ordered a month ago.

yeah, I'm totally spare time on this project, and have a few other spare time projects also competing for attention, so I'm not fussed (still need to order a PCB for the project too)
I'll get there someday. :-)
 

Offline Edwin G. Pettis

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Re: Group buy: LTZ1000 precision resistor set
« Reply #45 on: January 14, 2019, 04:19:39 am »
Halloween orders – update

I have been busy working on orders, while the holidays did slow things down a little (can’t ignore the wife all the time), I have finished and shipped all orders up to and through October 13th.  I have started production on orders from the 14th.  Some orders contained additional resistors over and above the LTZ and scaling resistor sets which took additional production time.  The same can be said for the remaining orders, a few are fairly large.  I am notifying everyone as I get near or start production of your order. Be assured I am making them as quickly as is possible.  I thank everyone for their patience and orders.

Best regards,

Edwin Pettis

Ultrohm Plus
 
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Offline MiDiTopic starter

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Re: Group buy: LTZ1000 precision resistor set
« Reply #46 on: January 14, 2019, 09:55:30 am »
Received mine last week, thank you Edwin!

Here is a selection of them:
 

Offline hwj-d

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Re: Group buy: LTZ1000 precision resistor set
« Reply #47 on: January 14, 2019, 10:45:40 am »
@ G. Pettis,

how long is the delivery of a current order of two ltz1000 sets likely to take?

Thanks
 

Offline Edwin G. Pettis

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Re: Group buy: LTZ1000 precision resistor set
« Reply #48 on: January 14, 2019, 11:31:36 pm »
@ hwj-d

Given the remaining quantity of resistors on order, I doubt I could get to any new orders sooner than the end of February most likely.  Two sets wouldn't take very long.
 
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Offline hwj-d

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Re: Group buy: LTZ1000 precision resistor set
« Reply #49 on: January 15, 2019, 10:07:11 am »
@ hwj-d

Given the remaining quantity of resistors on order, I doubt I could get to any new orders sooner than the end of February most likely.  Two sets wouldn't take very long.

PM sent.  :)
 


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