Author Topic: Resistor Set for LTZ1000 positive standard 7V circuit  (Read 22587 times)

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Offline lars

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #25 on: May 24, 2017, 05:30:02 pm »
As the drift sensitivity for the resistors is in the range of 1/100 and less, noise of the resistors should not be a real problem.

With TF resistors there is also a large variation between different versions. The more difficult properties are long term drift and humidity - the TC is just the parameter that is relatively easy to measure. The humidity effect can be less critical if used in an always warm circuit.

The high quality hermetical sealed TF resistors can be better in stability than many PWWs. Of cause the price is also high and availability is difficult with these.

It somewhat depends on the application whether long term drift is more important than noise.

I fully agree. But the same seems to apply for WW about humidity at least , and that I seldom see specified. And yes, with about 13C higher temperature the humidity drift is about half is my experience. The problem in my LTZ box with two aluminium boxes, with a peltier between (for future use and temperature tests), is that the resistors are only about 2-3C above room temperature.

For me the RN73, PCFxxx, ERAxx seems to be good candidates from testing, I guess PTF56 might be ok for through hole but I have not tested them yet.

Lars
 

Offline Andreas

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #26 on: May 24, 2017, 07:00:50 pm »
Hello,

what about UPF50/UPF25 resistors?
at least they had a very low hysteresis in my T.C. tests.

The two 1K resistors were around 2 ppm/K.

https://www.eevblog.com/forum/metrology/t-c-measurements-on-precision-resistors/msg462301/#msg462301

Would be interesting how they behave with humidity.

With best regards

Andreas
 

Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #27 on: December 28, 2017, 07:59:51 pm »
Hello,

I decided to summarize all of the results which have been linked to in this thread.

In the first table, the values are the percentage of drift which will appear in the output.  I.e., for 1%, that means a 100ppm change in R will result in a 1ppm Vz change.

In the second table, the results are normalized against R4/R5, so this is "importance of each resistor relative to R4/R5".

References:


Note: these results do not include any "R60" results.

Edit: the "average" column is only the average of the community-measured values -- it does not include the datasheet values.
« Last Edit: December 28, 2017, 08:02:54 pm by cellularmitosis »
LTZs: KX FX MX CX PX Frank A9 QX
 
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Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #28 on: January 03, 2018, 10:04:57 pm »
Just got my quote back from Rho point about the econistors.  These are the green wirewound resistors seen in Dr. Frank's LTZ1000 reference build.

https://www.eevblog.com/forum/metrology/mx-reference/msg1297126/#msg1297126

(Note that the quantities aren't correct -- there's only one 70k listed in the quote).

(Note also that shipping is half of the total!)

Edit: oops, I cropped out the shipping and total.

Edit2: Oh wait, actually the part number visible in Dr. Frank's photo says "8G16A", not "8G16D".  It looks like that is a different series (which might have better long-term stability?), but is only available in values 60R to 247R from stock: https://www.rhopointcomponents.com/components/resistors/precision-through-hole/rtd-simulation-resistors-100c-to-400c-8e16a-series.html.  It looks like he used that for the 120R?
« Last Edit: January 03, 2018, 10:15:18 pm by cellularmitosis »
LTZs: KX FX MX CX PX Frank A9 QX
 
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Offline Andreas

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #29 on: January 04, 2018, 04:19:15 pm »
It looks like that is a different series (which might have better long-term stability?),
Hello,

according to the ordering list:
https://www.rhopointcomponents.com/components/resistors/precision-through-hole/wirewound-econistor-3ppmc-8e16-8g16-series.html

A = 0.01% tolerance
D = 0.1% tolerance

0.1% tolerance is sufficient for a LTZ-Reference.
(see  application note AN86 Figure I2)

With best regards

Andreas
 
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Online Dr. Frank

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #30 on: January 04, 2018, 04:34:03 pm »


Edit2: Oh wait, actually the part number visible in Dr. Frank's photo says "8G16A", not "8G16D".  It looks like that is a different series (which might have better long-term stability?), but is only available in values 60R to 247R from stock: https://www.rhopointcomponents.com/components/resistors/precision-through-hole/rtd-simulation-resistors-100c-to-400c-8e16a-series.html.  It looks like he used that for the 120R?

A few of the 0.1% resistors (D) had been out of stock, so I needed to order some 0.01% (A).

0.1% or even 1% is fully sufficient.

Frank
 
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Offline Andreas

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #31 on: January 04, 2018, 05:10:17 pm »
0.1% or even 1% is fully sufficient.

Hello,

at +/-1% for the setpoint divider you should have another 5 deg C headroom for the setpoint against 0.1%.

With best regards

Andreas


 

Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #32 on: January 05, 2018, 02:57:54 am »
Followers of this thread will also be interested in this quote I just received for some Vishay hermetic foil resistors from Texas Components.

I asked about the following resistors and got a prompt reply:

Quote
Hello,

...

VHP202Z 120R 1% Y6071120R000F0L
VHP202Z 70k 1% Y607170K0000F0L
VHD200 12.5k / 1k divider 1% Y5076???????F0L

For the VHD200 hermetic dividers, is there a Z-foil version of those?

Thanks,
Jason

Quote
Hello Jason. Thanks for this new opportunity.

We can offer you the 3 items as you have them here.

The Z Foil exit for the 300144 series, but we don’t have chips in USA. They will be 25 pc. MOQ and 11 weeks ARO. You let me know if want them.

Meantime, let me quote what we can do here, with 3 weeks ARO, maybe sooner.

See below for unit prices,
Nelson

VHP202Z 120R00 1.0% (Y6071 120R000 F0L) @ $27.90 each
VHP202Z 70K000  1.0% (Y6071 70K0000 F0L) @ $40.95 each
VHD200 12.5k / 1k divider 1.0% Abs%Mat (Y5076 V0599 FF0L) @ $46.50 each

For the VHD200 hermetic dividers, is there a Z-foil version of those? Yes. See note above.

I was also thrilled to hear that Edwin Pettis is resuming resistor production!  Soon I'll be able to compare LTZ specimens with Vishay, Ultrohm, and Econistors.    :D

http://www.texascomponents.com/store/VishayFoilResistors.asp

LTZs: KX FX MX CX PX Frank A9 QX
 
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Offline beanflying

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #33 on: January 05, 2018, 04:45:52 am »
It has been nearly 2 weeks since I had a communication from Texas Components  ??? I was being forgiving as Christmas New Year is a PITA for everyone however I know have boards and LTZ's so ...... Hurray up  :horse:
Coffee, Food, R/C and electronics nerd in no particular order. Also CNC wannabe, 3D printer and Laser Cutter Junkie and just don't mention my TEA addiction....
 

Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #34 on: January 05, 2018, 06:33:29 am »
For some reason, their reply to me was flagged as spam, so even though I thought they hadn't replied for a week, it turned out they had replied same-day.  Can you check your spam folder?
LTZs: KX FX MX CX PX Frank A9 QX
 

Offline beanflying

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #35 on: January 05, 2018, 07:03:06 am »
I had been to and fro a few times to the one human but yep email from them on the 23rd of December in my Gmail spam folder  :horse: to google it seems  >:(

All good they only got back a day or so back anyway.  :-+

Also making a Vishay based Harmon divider, looking at it may have been cheaper to buy a s/hand fluke  :-DD

Wasn't any urgency when the LTZ's were due in Feb......
« Last Edit: January 05, 2018, 07:12:33 am by beanflying »
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Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #36 on: January 09, 2018, 10:45:35 pm »
Communication with Rhopoint seems a bit difficult.  When I edited my quote request to increase the quantity of the resistors, they updated the quote and more than doubled the price of the 12.5k resistors.  When I replied and asked about this, they just deleted the quote.  Strange.

Perhaps they have 2k and 25k in stock, and I can use those instead.

EDIT: This was a mistake on their part -- they meant to type "6.90" and instead typed "16.90"
« Last Edit: January 10, 2018, 04:20:42 pm by cellularmitosis »
LTZs: KX FX MX CX PX Frank A9 QX
 

Offline Edwin G. Pettis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #37 on: January 10, 2018, 03:10:40 am »
Cellular:

There is absolutely no reason that a 12.5K resistor should cost more than a 70K, it should be ~$3.00 less give or take....I find sometimes that RhoPoint quotes are silly.
 
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Offline Vgkid

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #38 on: January 10, 2018, 04:00:32 am »
If you didn't need them immediately, you are running close to the the minimum pricing needed from prime technology (general resistance)
If you own any North Hills Electronics gear, message me. L&N Fan
 
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Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #39 on: January 10, 2018, 05:05:19 am »
LTZs: KX FX MX CX PX Frank A9 QX
 

Offline Edwin G. Pettis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #40 on: January 10, 2018, 05:07:19 am »
RhoPoint get's their stock from General Resistance, I believe GR has something of a minimum order amount, you might not like it.
 
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Offline HalFET

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #41 on: January 10, 2018, 02:55:53 pm »
I ended up using platinum rtds once when trying to save cost on a LM399 circuit. If you build the circuit to be ratio based and thermally couple all the RTDs it did seem to work and showed almost no humidity sensitivity since the RTDs were glass passivated on alumina substrates, temperature stability was fairly good since these are manufactured with low tolerances.  Might be worth checking if the same trick could work for the LTZ1000 if you have too much time on your hands like I did back then  ;D
 
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Offline mimmus78

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #42 on: January 10, 2018, 03:50:42 pm »
Cellular:

There is absolutely no reason that a 12.5K resistor should cost more than a 70K, it should be ~$3.00 less give or take....I find sometimes that RhoPoint quotes are silly.
Maybe they consider 12.5k custom built one :-).
 

Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #43 on: January 10, 2018, 04:19:54 pm »
Paul from Rhopoint reached out to me -- this was just a mistake.  He meant to type "6.90" and instead typed "16.90".

Prime Technology got back to me -- the minimum order is $250.  I've asked for a quote anyway, just to find out how many people would have to do a group buy in order to make it work.
LTZs: KX FX MX CX PX Frank A9 QX
 

Offline rigrunner

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #44 on: January 10, 2018, 08:07:52 pm »
Quote from: cellularmitosis
Communication with Rhopoint seems a bit difficult.

I've got a request in with them for some FLCY resistors. How long did it take for your first quote to be responded to?
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Offline Edwin G. Pettis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #45 on: January 10, 2018, 09:05:00 pm »
A set of LTZ resistors from me is $37.90, I give discounts, no minimums.  The question is; why are you fussing with Rhopoint and their nothing special resistors plus high shipping?
 

Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #46 on: January 10, 2018, 09:18:49 pm »
Well, my intention was to have a set of econistors, a set of Vishay BMF's, and a set of your resistors and compare them all, but it looks like I'll be waiting on the econistors for a while yet.
LTZs: KX FX MX CX PX Frank A9 QX
 

Offline Andreas

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #47 on: January 10, 2018, 10:42:06 pm »
Well, my intention was to have a set of econistors, a set of Vishay BMF's, and a set of your resistors and compare them all, but it looks like I'll be waiting on the econistors for a while yet.
Hello,

with one set alone of each you cannot judge whats really going on.

Currently I am measuring some econistors.  (3 sets)
Unforunately they have a relative large stray of parameters (at least the 70K see latest post).
And if you think it cannot get worse: wait until I have measured the 8G16 120R resistors.
(I am not really happy with the first result).
And also Frank had its issues with some low ohmic econistors in the past.

So from the PWWs I´d prefer Edwins resistors.
If you handle them with care (using pliers for bending the leads) they are your friend.

with best regards

Andreas
 
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Offline cellularmitosis

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #48 on: January 10, 2018, 11:06:16 pm »
SO FAR I have  ordered 3 sets of everything.  Not really statistically significant, but more informative than just one set.
LTZs: KX FX MX CX PX Frank A9 QX
 

Offline Andreas

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Re: Resistor Set for LTZ1000 positive standard 7V circuit
« Reply #49 on: January 10, 2018, 11:11:47 pm »
SO FAR I have  ordered 3 sets of everything.  Not really statistically significant, but more informative than just one set.
Hello,

Ok then you should be able to select the best. (after measurement).

with best regards

Andreas
 


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