Schematics on Resistor Simulation by Calibrators - Page 1
Forum section: electronics / general

author: Echo88
author_rank: Frequent Contributor
timestamp: August 11, 2017, 08:18:04 pm
content: Calibrators like the Fluke 5500A generate a variable resistance on its output by using a "Synthesized Impedance Assembly". download.flukecal.com/pub/literature/5500a___smeng0600.pdf Page 48Id like to learn from it and perhaps someone can provide suitable schematics of such an assembly? I havent found anything, but maybe there are old calibrator service manuals which include those schematics.

author: lukier
author_rank: Unknown
timestamp: August 11, 2017, 10:30:09 pm
content: Interesting. I would like to know more about this as well.Is it similar to the approach used in Valhalla 2724A? They call it active ohms and it looks very similar (a reference resistor plus a variable gain amplifier).

author: CalMachine
author_rank: Frequent Contributor
timestamp: August 11, 2017, 10:40:46 pm
content: This might be the same information, reiterated... but it might be worth a look.http://download.flukecal.com/pub/literature/9100_vo1umeng0000.pdfSections 4.7.5.3 and 4.7.5.4 have a slightly more detailed graphic.

author: lukier
author_rank: Unknown
timestamp: August 11, 2017, 11:15:14 pm
content: Thanks CalMachine.I first became aware of this technique when I encountered Valhalla 2724A mentioned here on the forum and studied the service manual a bit. I always thought resistance calibrators are just a lot of precision resistors and relays, like in Fluke 5450A, but to my surprise the specs of 2724A are almost as good (I guess derived from few quality resistors + LM399), while being much more versatile.Experimenting with this type of resistance standard is on my TODO list now (that usually means never) and I wonder what the limitations are. 2724A goes up to 12 GOhm which is a lot. I guess one cannot use this approach to calibrate things like LCR meters or possibly electrometers (different resistance measurement scheme).

author: CalMachine
author_rank: Frequent Contributor
timestamp: August 11, 2017, 11:22:15 pm
content: Quote from: lukier on August 11, 2017, 11:15:14 pmThey can actually be a pain to deal with sometimes. With the 9100, as it was designed to calibrate handheld multimeters. In my experience, when you go to try and measure resistance via 4 wire measuring device, like a 3458A, they often don't cooperate with each other. A 5500 or 5520 work flawlessly with a 3458A.You are also correct, that cannot use this type of resistance source to calibrate certain types of equipment. For instance, a Megaohmeter or Electrometer.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 12, 2017, 09:18:20 am
content: Sadly there are no schematics/service manuals available for both Wavetek 9100 and Valhalla 2724A, although the Wavetek graphic makes the practical approach a bit clearer.

author: lukier
author_rank: Unknown
timestamp: August 12, 2017, 09:40:53 am
content: Quote from: Echo88 on August 12, 2017, 09:18:20 amArtek sells the 2724A service manual for IMHO a reasonable amount:http://www.ebay.co.uk/itm/390595429766http://artekmanuals.com/manuals/other-manuals/

author: TiN
author_rank: Super Contributor
timestamp: August 12, 2017, 09:59:05 am
content: However there is schematics ofFluke 57LFC, which is essentially5522Amix of 552x and 57xx in system only rack chassis.No resistance synth in this one though.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 12, 2017, 10:11:36 am
content: Indeed a reasonable amount. But i searched a bit more and found it:http://www.lost-manuals.com/equipment.php?id=15380Also just uploaded it tohttp://www.ko4bb.com. Since youre also watching TiN: This would also be useful in the xdevs archive?Well, time to study.Edit: Seems the first page of the schematic is missing. So it doesnt tell the whole story.Edit2: Found the missing first page. Now its complete.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 12, 2017, 10:15:53 am
content: The Fluke 57, just like the 5200A, is not capable of producing a programmable resistance, it can only output its built-in-standard resistor values.

author: fcb
author_rank: Super Contributor
timestamp: August 12, 2017, 04:58:14 pm
content: Quote from: TiN on August 12, 2017, 09:59:05 amThat is a shocking level of detail & schematics to! Surprising especially since they are dated 2004. Book marked.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: August 13, 2017, 07:23:23 am
content: Fluke patents

author: martinr33
author_rank: Frequent Contributor
timestamp: August 13, 2017, 07:58:15 am
content: Quote from: TiN on Yesterday at 07:59:05 PMHowever there is schematics of Fluke 57LFC, which is essentially 5522Amix of 552x and 57xx in system only rack chassis.No resistance synth in this one though.and from fcb:That is a shocking level of detail & schematics to! Surprising especially since they are dated 2004. Book marked.That manual is for the Navy and its contractors, same idea as that Fluke 2001 manual that appeared. The US military probably has these manuals for everything we see. That means they will eventually slip out.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: August 13, 2017, 11:51:58 am
content: Simplified Valhalla schematics (with software MDAC) working is very well.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 13, 2017, 12:13:42 pm
content: Youre ahead of us as always i see.

author: lukier
author_rank: Unknown
timestamp: August 13, 2017, 07:15:01 pm
content: Quote from: Mickle T. on August 13, 2017, 11:51:58 amEvery time some metrology idea comes up it turns out Mickle T. already did itChapeau bas!

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: August 13, 2017, 07:18:19 pm
content: Quote from: lukier on August 13, 2017, 07:15:01 pmI am patiently waiting for Mickle T. to show us his homebrew JJA.

author: carl_lab
author_rank: Frequent Contributor
timestamp: August 14, 2017, 09:34:29 pm
content: Has anybody realized an inductor simulation (virtual inductor) for calibration purpose?http://downloads.hindawi.com/journals/apec/1989/039762.pdf

author: lukier
author_rank: Unknown
timestamp: August 14, 2017, 11:08:25 pm
content: Quote from: Mickle T. on August 13, 2017, 11:51:58 amI have few questions about this circuit. I hope you don't mind.If I guess the operation correctly, you route one of the leads from the DMM to the X3-VIN input, while being grounded via the reference resistor (jumper wire on the photos), that voltage drop across the reference resistor gets amplified by U22:A and resistors via DG413 and goes to AIN0 of the ADC. Now purely in software, no analog loops, you read that from the ADC and program the DAC accordingly to drive the X5-VOUT that goes to the second lead from the DMM, thus generating voltage across the DMM leads that the DMM converts into the resistance. The VSENSE from the DAC is fed into the ADC for the digital feedback loop.I suppose that in 4W mode you just connect negative force and sense to the negative binding posts, no special care required.1) what are the resistor networks R10, R21 (M3NRE001S-VERT) and R24 (DIVSTAT-10-100) - couldn't find anything on those. R24 resembles something like CADDOCK 1776?2) it is described as Hamon, but where is the Hamon autocal action, that is series-parallel rewiring the upper leg of the divider?3) what is the purpose of ZSENSE ADC input?4) how good is your autocal? I see feeding the raw LM399 voltage into the ADC input front end to adjust for that, but is this going to take care of the reference scaling done by R10 and R24 (thus DAC calibration as well)?Thanks!

author: hwj-d
author_rank: Frequent Contributor
timestamp: August 15, 2017, 04:11:50 am
content: Quote from: lukier on August 14, 2017, 11:08:25 pmThats my questions too.Maybe, these are the resistors and black boxes in the left down corner:https://www.eevblog.com/forum/metrology/lm399-based-10-v-reference/msg1110430/#msg1110430Seems to be some russian gear?

author: Mickle T.
author_rank: Frequent Contributor
timestamp: August 15, 2017, 06:07:27 am
content: 1) M3NRE001S (black boxes) - metrological level custom BMF divider. Used in the standard laboratories DC voltage references.R24 (DIVSTAT-10-100) - DIY Hamon type divider without autocal action (20 pcs hermetic BMF resistors on the subboard).3) ZSENSE is used for LO-to-LO current path voltage difference measurement.4) Currently a LM399 voltage isn't used in autocal procedure.

author: LaserEng
author_rank: Regular Contributor
timestamp: March 25, 2019, 06:58:08 am
content: Sorry to resurrect an old thread but I have the service manual with schematics of Fluke 5500A, including impedance synthesizer schematics.The full service manual is too big to attach to the post, it can be downloaded from the dropox link below for your reading pleasurehttps://www.dropbox.com/s/48p5qlqob1f4ysj/FLUKE%205500A%20SERVICE%20MANUAL%20WITH%20SCHEMATICS.pdf?dl=0

author: chekhov
author_rank: Regular Contributor
timestamp: March 25, 2019, 08:45:05 pm
content: Thanks LaserEng,Maybe it is possible to upload this toko4bb.comwhich seems to be the right place to share this precious thing ?

author: LaserEng
author_rank: Regular Contributor
timestamp: March 27, 2019, 12:59:12 am
content: Thanks for the link, manual now uploaded to ko4bb.

author: bfsy
author_rank: Newbie
timestamp: March 18, 2021, 09:55:50 am
content: Thank you for sharing the 5500A schematics.FLUKE 5520A Error 1504 when trying to output 100kohms 10kohms 1kohms ...But no error when output 1Mohm 10Mohm ...Who has the 5520A schematics

author: LaserEng
author_rank: Regular Contributor
timestamp: March 18, 2021, 04:32:04 pm
content: Fluke 5520A service manual is available at Xdevs site but sadly no schematicshttps://doc.xdevs.com/docs/Fluke/5520A/5520a___smeng0100.pdf