hybridfree/eevblog-posts huggingface dataset:
ad588 , another cheap project - Page 1
Forum section: electronics / general

author: GigaJoe
author_rank: Frequent Contributor
timestamp: August 12, 2025, 06:16:48 pm
content: second though , i drop an idea glass , LT1021 ,oil , and all this thingy , as anyway it plastic and crystal isolation mediocre.Couple days i bow down to REF80 , then realize it against my religion nature in believe as cheap as possible , it around 200+ non Yankee bucks , and walk away ....So AD588 (not 7, not 6, notBob) and cornerstone of everything of course The Capacitor!if we have noise pin , need to hook, and not crew up, need The Capacitor!So i set my low noise voltage source to 10V , 100K current sense resistor , noise approx 5-15 microvolt noise , jumping ..and we measure :top red audiophiller 22Uf , and small 10UF , approx. the same, close to the noise level .. let say approx. 50G resistancethen spirit - close to 50uV so around 20Gthen yellow JFGA 47uF - already 70-90uV let say 10Gand 2 bottom a faulty one , it salvaged from 240V working equip, cap 8-9uF , ( not 20uF as labeled)and i did calculate wrong it 1G and 3G( all caps i clean in isopropyl and and handle accordingly )

author: iMo
author_rank: Super Contributor
timestamp: August 13, 2025, 09:54:53 am
content: You may try the "discharge method" (provided your meter has a highZ input). Wire the capacitor to the meter's inputs, charge it to those 10V, after some soaking remove the 10V and measure the discharge rate.The aprox capacitor's leakage current  = discharge rate [V/sec] * capacity I made such a measurements with wima 3u3/50V foil recently and got aprox 80G resistance at 10V..
Fluke 332D Sample String Linearization Adjustment - Page 1
Forum section: electronics / general

author: sevarre
author_rank: Contributor
timestamp: August 14, 2025, 03:35:06 am
content: I am looking for some guidance on doing the sample string linearization adjustment for my Fluke 332D/AB (yes, a strange -/AB variant).I am looking to avoid a Fluke 731 or 732 (and of course, avoid a Weston cell).Basically what I am interested in doing is this:(1.) DC voltage standard -> (2.) Kelvin Varley divider -> Fluke 845AR -> DUT (Fluke 332D)For the DC standard I am looking at ab-precision.de DVR1 (10V @ 2ppm and 0.25ppm/K) or voltagestandard.com vref10-001 r9 (10V @ 10ppm and 0.4ppm/oC).For the KVD, of course a Fluke 720A would be ideal, but I am wondering if I can get it done with an ESI RV722. The ESI unit has 1ppm linearity, but it says it can be "certificate corrected" to 0.2ppm. The Fluke 720A has 0.1ppm linearity.I have attached a crude image of my proposed set up. Does this set up not work for some reason? It seems OK to me, but I am not an experienced voltnut.I am not sure about the cable shielding/ground connections- I copied as best I could from the Navair 17-20AE-103 document regarding the 332D (see page 8 ).https://bama.edebris.com/download/fluke/332/Calibration_Procedures_US_Military/NAVAIR%2017-20AE-103.pdfThanks for any insights or feedback!

author: zlymex
author_rank: Frequent Contributor
timestamp: August 14, 2025, 11:20:39 am
content: Alternatively, just use 3458A 10V range

author: sevarre
author_rank: Contributor
timestamp: August 14, 2025, 04:16:08 pm
content: Quote from: zlymex on August 14, 2025, 11:20:39 amOh I wish!
GW Instek GDM-8255A - Page 1
Forum section: electronics / general

author: cepsbow
author_rank: Newbie
timestamp: July 30, 2025, 05:50:29 pm
content: https://www.ebay.com/itm/356441206317Excellent deal, can't wait to see it in person.https://www.gwinstek.com/en-US/products/detail/GDM-8255AThe guy has an excellent selection of lab equipment as well, more on the GCMS side of things, really neat shop though.https://www.ebay.com/str/yuhanusa

author: edavid
author_rank: Super Contributor
timestamp: July 30, 2025, 06:28:32 pm
content: $105 shipping makes it less excellent

author: cepsbow
author_rank: Newbie
timestamp: July 30, 2025, 10:26:01 pm
content: He's taking offers and it's shipped UPS surepost from Taiwan. I'm sure there could be cheaper shipping options you can findAnd do not forget that it comes with a scanner card.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: August 11, 2025, 08:37:36 pm
content: have 8251 , 55 are 200000 , 51 - 120000 ; own custom gwistek ADCquite disastrous design ... power supply switching 5V, then onboard boost to ±16 , and 78(9)12 , booster running around 100K , 7812 cant filter it at all , all this noise leak to the analog measurement, usually 2 last digits randomly jumping.everything I'm able to do add a lot 1000uf caps on top of existing, on 5V and boost converter, i does suppress noise so fluctuation just LSB ±1-2 digits ....Vref ARD421 SOIC-8 , acceptable.what is not good a divider with high tempco and current source as well .... so unfortunately it not so precise as 5digit fluke or HP , a breeze from aircond and unit start slowly drifting away .... you really dont kow is it you or device ...cal switch , btw, usb with ground and 5V shorted ( consider 50 ohm resistor - just in case)when i did cal, as I remember , 10V precise for input calibration converted to 10.0007 V as readingso i have to decrease 10 to match reading precise 10.0000 ,no idea why guess errors in software ..so in overall kinda sour taste , only positive are dual display
ACS37800 Temperature Error related question - Page 1
Forum section: electronics / general

author: macck
author_rank: Contributor
timestamp: August 11, 2025, 03:43:18 pm
content: Hi,I'm looking into acs37800 to implement some line power mesaurements into my devices.I was reading through datasheet and it got me confused.On one hand diagrams show that device is temperature compensated internally, on the other, there is whole chapter dedicated to"Temperature error exists, here is at 25 deg, -40 deg, +125 deg, please consider it".After reading this Allegro Datasheet im not sure if there are some ways around it, or what.My issue is, that devices connected can be also drawing under 100W, where temperature impact on measured current goes non-linear.For 25 degrees it seems manageable, but for edge-cases it is questionable. Big question is what happens between?I could probably spare some temperature sensor to compensate (as i see no way to read value of internal temp sensor), but I cannot find any information whether this can be done reliably.Do you have any experiences with this chip? I'd say, if I could get it to 5% accuracy, over 0.1-10A range, that would do, but these charts look horrible for the job.

author: mendip_discovery
author_rank: Super Contributor
timestamp: August 11, 2025, 06:29:18 pm
content: I am no expert, so this makes me fully qualified to answer.The spec sheet says 25 °C to 125 °C, the spec is 3.4% of error, and -40 to 125 °C it's 3.5% the pretty graphs are just showing that typically there isn't much error due to temp, unless it's at -40 °C to 25 °C.I suspect that if you could keep the package as close to 25 °C as you can, the better.It does state that its shouldn't get above 165 °C as that can cause issues with the chip.FYIhttps://www.allegromicro.com/-/media/files/datasheets/acs37800-datasheet.pdfis where I looked it up.

author: macck
author_rank: Contributor
timestamp: August 11, 2025, 07:08:57 pm
content: Thanks for replying!Okay,I see that this is specified for Ip(Max), and for Ip(min) there is min/max offset value at Ip=0A of ~300-400mA.So therefore I'd assume, that each device should be able autocalibrate offset knowing that load is disconnected.There is description of QVO calibration procedure to get rid of the offset and if i see correctly, also ability to tell the device of initial/nominal room temperature value.So maybe it is enough to just calibrate it at known temperature, and internal compensation would do rest of the job?Keeping constant temperature is rather unfeasible in my application, but 3.5% of error is acceptable for the job.
extremely noisy signal with oscilloscope - Page 1
Forum section: electronics / general

author: Slania87
author_rank: Newbie
timestamp: August 05, 2025, 05:15:33 pm
content: Hi!I have to measure an electrical interference signal and it is very noisy. It derives from a DC stimulator, a 653 and 643 Hz signal.The oscilloscope used: Digital Storage Oscilloscope 100MHz MP720665Note: I was not able to upload every screenshot, but I hope, one can follow it.The measurement setup:Screenshot 2025-08-05 115717.pngNote: at the end of the probes and the stimulator outputs are silver electrodes.Group 1, Grouped objectI tested it as follows:1. Executed self calibration2. Probes compensation: (3.3V/1kHz)It looks fine for me.3. For testing, I used two signals: 600 Hz and 610 Hz: (I can only upload one picture. It is the 600 Hz measurement. The 610 Hz and the interference of these two signals are fine.)1754388577268.pngOn the other hand, when I used the signals of 653 and 643 Hz, the signals are very noisy.1754388059356.png1754388107696.pngThe interference:1754388155759.pngThese are very noisy.Also, I measured the noise of the oscilloscope and the probes, they are very significant:1754389033523.pngAlso, when I took the probe between the two silver electrodes attached to the oscilloscope, there is also a significant noise, but it changed to measure the signal in ampere. The SECOND picture is the first 1000 elements of the signal.1754389370306.pngCan You advise me anything in this matter?
NEW LHY UCCM GPSDO  - Page 1
Forum section: electronics / general

author: FPSychotic
author_rank: Regular Contributor
timestamp: August 02, 2025, 11:55:29 pm
content: I got a new GPSDO from. The company LHY, model UCCM. It is quite nice, well built, square and sine signals, lacks 1Hz pps output, I'm not able to connect to u-center or Lady Heather, I think it is a hardware issue. To be honest I don't care, I'm hobbist ,no clue about how to use Lady H. and also not many interest in to learn, whatever it does is more I need. But it is well build and the square signal made my LibreSDR lock external reference, and that never happened with my other B7Lxxx GPSDO (without screen). So having the other, I prefer this. Very well priced. I got with it all my equipment in same clock , the other couldn't .I used a minicircuits 3 ports splitter.Square signal is around 10dbm, sine is 9dbm,https://s.click.aliexpress.com/e/_EyvvC2E

author: Vgkid
author_rank: Super Contributor
timestamp: August 03, 2025, 01:14:38 am
content: I wonder if the classic uccm gpsdo is inside...Time to open it up.

author: isometrik
author_rank: Regular Contributor
timestamp: August 03, 2025, 02:15:14 am
content: The linked AliExpress item has photos showing the internals. We can see a Samsumg UCCM module.

author: FPSychotic
author_rank: Regular Contributor
timestamp: August 03, 2025, 02:27:23 am
content: Also Lea-6t, it has a fpga too.
HP 53181A counter with opt 001 : reference clock drift days after power-up - Page 1
Forum section: electronics / general

author: sorenkir
author_rank: Regular Contributor
timestamp: April 11, 2025, 01:50:38 pm
content: Hello all,My instrument is a HP 53181A from 2002, with opt 001 (medium-stability timebase = ISOTEMP OCXO33-46, datasheet attached).Now that I have a Leo Bodnar LBE-1420 and a TinyPFA analyzer, I wanted to check the stability of the OCXO, and calibrate the counter.The graph below shows frequency difference of the '10MHz Output' at the back of the counter compared to the GPSDO output, from power-up of the instrument. Temperature of the room did not change much along the test.HP recommends to have the instrument on for 24 hours before performing calibration, but now the counter has been on for 5 days and the OCXO is still drifting.I don't know if it is to be expected or if it is the sign of some fault.What do you think ?Thanks.Michel.

author: MIS42N
author_rank: Frequent Contributor
timestamp: April 25, 2025, 09:55:53 am
content: Nobody seems to want to reply, so here goes. Looking at the OCXO specification and HP specification I read it as saying:Aging Rate Per Day: < 4 x 10-8(after 30 days) Per Month: < 2 x 10-74 x 10-8= 0.4Hz @ 10MHz and after 48 hours that's about what your graph showsAnd after a month it may be 2Hz out.You don't say what previous use this instrument had, it looks like what happens after not being turned on for a while.I don't see reason for alarm. It depends on what you do with the counter next. If you are OK with measurements within 2 x 10-7then you are OK to calibrate it and use it. If you want better accuracy, there is the option (according to the brochure) to feed in 10MHz from your GPSDO.I like the idea of leaving an OCXO running and not moving it.

author: SCSKITS
author_rank: Regular Contributor
timestamp: August 01, 2025, 06:23:55 am
content: If the OCXO has been sitting around for a while (in the OFF state) it may need to be "burned in" before the drifting calms down. Usually after a few days/weeks, it should be stable. The 53181A has a self calibration, can I assume you ran it? You can connect the BODNAR unit to the input of the counter to run the cal.Are you sure that it is the OCXO that is drifting and it is not an issue with the tinyPFA?Connect the output of the Bodnar unit to both inputs through a splitter to check.You are off by 2Hz at 10MHz. It should be better than that. HP/Agilent usually uses stable OCXOs in their counters. This one could have an issue..Another way to check for drift of the OCXO is to just measure the output frequency of the BODNAR unit with the 53181A over time. Gets the tinyPFA out of the circuit.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 02, 2025, 03:31:44 pm
content: A simple thing you can test is whether the oven itself actually works. It should draw some significant current after startup, and then reduce the current as it heats up within a few minutes.
Metrology Society Conference and NMIA Site Tour - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: July 07, 2025, 06:29:54 am
content: This upcoming conference in Sydney sounds good, I'm think about going.https://metrology.asn.au/events/msa-conference-sydney-aus-25-28-august-2025/I've been given a ticket to the tour of the National Measurement Institute of Australia, and I've been given permission to film.Also thinking about joining the MSA, but it apparently needs to two members to sponsor you for full membership?

author: Korchahin
author_rank: Regular Contributor
timestamp: July 07, 2025, 05:04:10 pm
content: We will all be incredibly happy if, for some completely random reason, JJA disappears from the Australian Institute.And in a few days, Dave's channel will feature reviews and calibrations of his measuring equipment using JJA.We are waiting for an exciting video from the tour!

author: EEVblog
author_rank: Unknown
timestamp: July 21, 2025, 05:44:11 am
content: Unfortunately the invite to video the tour was a bit premature, I'm not allowed to film

author: Vgkid
author_rank: Super Contributor
timestamp: July 21, 2025, 06:00:58 am
content: Thats unfortunateWill we atleast get an EEV video on it?

author: EEVblog
author_rank: Unknown
timestamp: July 21, 2025, 06:31:10 am
content: Quote from: Vgkid on July 21, 2025, 06:00:58 amCan't do a video if I'm not allowed to film anything.

author: Vgkid
author_rank: Super Contributor
timestamp: July 21, 2025, 06:37:04 am
content: Quote from: EEVblog on July 21, 2025, 06:31:10 amAh , I thought you could at least talk about the conference/ what you saw.

author: EEVblog
author_rank: Unknown
timestamp: July 21, 2025, 06:41:35 am
content: Quote from: Vgkid on July 21, 2025, 06:37:04 amThat would be pretty boring I'm afraid.They are going to stream the "Metrology 101" part of the conference on the 27th August, presumably on the MSA channel.

author: Vgkid
author_rank: Super Contributor
timestamp: July 21, 2025, 08:34:39 am
content: Quote from: EEVblog on July 21, 2025, 06:41:35 amGotcha, do let us know if you have any more information.

author: binary01
author_rank: Contributor
timestamp: August 02, 2025, 12:13:33 pm
content: Quote from: EEVblog on July 07, 2025, 06:29:54 amI'd be very happy to sponsor your membership, Dave, if you decide to join!It's a bummer about the restrictions on videoing the NMIA tour, as I'm sure it would have been very interesting to the EEVBlog communityI've toured the NMIA electrical metrology section before and it's fascinating, as are the scientists that run it.I hope to see you and some other EEVBlog members at the conference.Anyone with any questions about the conference or joining the MSA, shoot me a PMEdit:Anyone wanting to attend the free 101 session, in-person or online, the link to register is here:https://metrology.asn.au/events/metrology-101-free-session/
MLUNOVÉ ZRIEDLO  - Motor based ultra low leakage [150nV] power supply  - Page 1
Forum section: electronics / general

author: felixd
author_rank: Regular Contributor
timestamp: August 04, 2025, 09:59:39 pm
content: If you're working with ultra-sensitive DC metrology, you’ll want to take a closer look at the experimentalDMI 664fpower supply, dubbed the Mill-type source with ultra-low leakage and increased noise. Developed by theDúbravský Metrological Institute, this unorthodox device employs a fully regulated motor-generator architecture to achieve exceptional galvanic isolation, with leakage currents as low as 150 nA.While the acoustic footprint is deliberately high - earning it the nickname the noisiest precise power supply in the business — its performance in reducing ground loop interference and parasitic coupling is genuinely impressive.This humorous yet technically grounded article dives deep into regulation dynamics, phase synchronization of 6-phase generation, sigma-delta feedback, and more. If you care about serious metrology and don’t mind a bit of "mechanical music" in your lab - this is absolutely worth a read and watchFull article here [In Slovak]:https://dmi.wtf/AP/annales_II_1.pdfI have also attached English, Google Transalted PDF version of above documentMotor-generator based power supply start-up:Motor-generator based power supply start up :Ultra low leakage power supply regulator response to step load:Marco Reps attempt to build simmilar Mill-type device (without luck I would say)https://youtu.be/9JinSfCKuNQ?t=812Cheers.
GPS-disciplined 555. Yes, you read that correctly.  - Page 1
Forum section: electronics / general

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: July 26, 2025, 03:36:27 pm
content: When people have tons of time in their hands to pursue the most preposterous ideas.https://hackaday.io/project/203528-gps-disciplined-555-timer

author: fourfathom
author_rank: Super Contributor
timestamp: July 26, 2025, 03:52:09 pm
content: That is a nicely-done hackaday article. Yeah, why would you want to discipline a 555, but in describing the process a lot of good ground is covered (which I'm sure was the point.)

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: July 26, 2025, 04:51:30 pm
content: I am not criticizing the circuit itself, I believe it is quite ingenious and good engineering was required to develop it.And the results, although disappointing by the authors own admission, it is a good example on how the 555, a very old dog indeed, can still be shown to play new tricks.I am only amazed that people have the patience to figure it out.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: July 27, 2025, 11:25:13 pm
content: Quote from: UnijunctionTransistor on July 26, 2025, 04:51:30 pmI'm not sure what they expected ?This is basically measuring the noise floor/jitter of a RC oscillator, comes in about one part in 30,000 per period. Pretty much 'as expected'.I wonder if the 'better 555' from Advanced Linear Devices ALD7555SAL or the CSS555 gives any better results ?The 4000 series logic dates from the same era as NE555, I wonder how a HEF4541/CD4541 compares = RC osc and binary divider.

author: iMo
author_rank: Super Contributor
timestamp: July 28, 2025, 05:07:23 pm
content: Quote from: UnijunctionTransistor on July 26, 2025, 03:36:27 pmI know in person a busy professional guy who once ran linux on an atmega1284p, while the booting took 12 hours.. Those are people who like challenges, sometimes pretty extravagant one. And the Hackaday is full of those..
FE-505B Datasheet - Page 1
Forum section: electronics / general

author: Birb
author_rank: Contributor
timestamp: July 22, 2025, 02:21:37 pm
content: Does anyone have the datasheet for the FE-505B? It has a strange pinout unlike the 505A and 405A, and notably lacks an SMA RF output.While I was successful in locating its patent and associated product line, it appears there is little to no technical information on the 505B, not even on FE's old website. (Only the A variant is ever explicitly mentioned)Attached is an image from a yahoo auction on this oscillator. Does anyone know what connector type this is also?Any help is appreciated, thanks!
Adret 104 voltage reference schematic ?  - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: November 06, 2024, 03:18:12 pm
content: HelloDoes some one have a schematic , this Voltage source is still in use in some lab performances are impressive but as that old ??Perhaps with the schematic and the components available in 2024 that possible to built a clone ?There is also a 103 model for both current and voltage source.RegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: November 06, 2024, 07:32:40 pm
content: HelloI link the patent ( in French )Adret works following schematic Fig 2 ( Figure = picture )RegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: November 07, 2024, 03:01:19 pm
content: HelloThis forum subject is linked :https://www.eevblog.com/forum/projects/making-a-pwm-based-voltage-standard/But no circuit schematic is providedRegardsOS

author: RLMCN
author_rank: Contributor
timestamp: July 19, 2025, 06:18:42 am
content: Hello,Please forgive me for coming to this topic a bit late — I'm not sure if it's still relevant.Just in case, here is the documentation I have on the 104.These are instruments I'm quite familiar with (especially the 103), and I'd be happy to help if I can.Best regards.Adret 104A Fiche Technique ProvisoireAdret_104_MaintenanceAdret_104_SubAssemblies

author: RLMCN
author_rank: Contributor
timestamp: July 19, 2025, 06:20:12 am
content: Adret_104_SchematicsAdret_104A_Manuel_Utilisateur

author: RLMCN
author_rank: Contributor
timestamp: July 19, 2025, 06:21:24 am
content: Adret_104A_Fiche_TechniqueAdret_104A_Manuel_UtilisateurAdret_104A_Parts_List

author: RLMCN
author_rank: Contributor
timestamp: July 19, 2025, 06:22:24 am
content: Adret_104A_User_Manual

author: RLMCN
author_rank: Contributor
timestamp: July 19, 2025, 06:24:25 am
content: Adret_104_Schematics
Wheatstone Bridge Manual - Page 1
Forum section: electronics / general

author: C-47
author_rank: Regular Contributor
timestamp: July 08, 2025, 06:41:26 am
content: Does anyone have or know where I might find a manual or other info on a JJ Instruments BR5 meter, initial searching seems to turn up little.Thanks, Alan.

author: Poroit
author_rank: Frequent Contributor
timestamp: July 08, 2025, 08:47:27 am
content: G'day C-47,You may need to compile your own by referring to similar models from others.eg PYE Portable Wheatstone Bridge, Leeds & Northrup 4725 etc.https://www.eevblog.com/forum/metrology/ln-4232-wheatstone-bridge/25/Does your JJ unit function OK?

author: C-47
author_rank: Regular Contributor
timestamp: July 08, 2025, 09:11:40 am
content: Hi Poroit, thanks for the response, not sure as its listed for sale on the other side of Oz, no internal battery.

author: Overspeed
author_rank: Frequent Contributor
timestamp: July 08, 2025, 11:21:25 am
content: HelloJJ is now a part of AMETEK company ( since 2016)RegardsOS

author: C-47
author_rank: Regular Contributor
timestamp: July 09, 2025, 01:43:05 am
content: Thanks, will try and email them.

author: C-47
author_rank: Regular Contributor
timestamp: July 17, 2025, 06:51:49 am
content: Just an update, have contacted Ametek a very diverse company, while very helpful, they have not found any info so far on this unit, so assume this comes to a close. Thanks for the help, Alan.

author: EC8010
author_rank: Frequent Contributor
timestamp: July 17, 2025, 09:29:36 am
content: Have you tried looking in Scroggie's "Laboratory Handbook"? Whilst it probably doesn't mention JJ by name, it certainly covers bridges and may have some useful pointers.
Antique metrology class German Amp-meter from 1937 - Page 1
Forum section: electronics / general

author: Micke
author_rank: Regular Contributor
timestamp: July 08, 2025, 07:40:25 pm
content: I bought this lovely piece of kit at a flea market this weekend.It is a 5A metrology class ammeter for both AC and DC.The condition is near mint! It was manufactured on December 31st 1937(!)The three crowns show that it belonged to the Swedish military.I have tested it (only on DC, so far) and it works perfectly!Note the lead seals on the screws!

author: Micke
author_rank: Regular Contributor
timestamp: July 08, 2025, 08:22:42 pm
content: Upps sorry, realize it is made in Austria! (Vienna) 🙈

author: TimFox
author_rank: Super Contributor
timestamp: July 08, 2025, 08:35:35 pm
content: Lovely instrument!Looking carefully at the certificate I noticed that they didn't have one available for current, so used one written for voltage with Volts crossed out.They also didn't intend the certificate for a long life span, since the date entry was for 193__.

author: EC8010
author_rank: Frequent Contributor
timestamp: July 08, 2025, 10:44:43 pm
content: What a wonderful piece of history! OK, so you're unlikely to ever use it for real (although I'd happily invent a need for its use), but it is a thing of great beauty even though She Who Must Be Obeyed (SWMBO) probably thinks differently.

author: unseenninja
author_rank: Regular Contributor
timestamp: July 11, 2025, 06:41:17 pm
content: Stunning piece of kit! It almost looks brand new.It is genuinely beautiful. Not something I could say about modern test equipment.

author: Micke
author_rank: Regular Contributor
timestamp: July 11, 2025, 08:28:38 pm
content: I would almost classify this instrument as mintLook at the finish in the varnish!Had to Google, December 31st 1937 is Anthony Hopkins birthday!Poor guys in the factory, no leave for New Years Eve!But amazing how this piece of equipment has survived 87 years this well...

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: July 11, 2025, 08:36:50 pm
content: Quote from: Micke on July 11, 2025, 08:28:38 pmMore so when one considers the turbulent period during its first years of existence.Of course, Sweden was neutral, which definitely helped.EDIT: Beautiful piece of equipment. Simply beautiful. It is in such great condition that it looks like a restored museum piece.

author: TimFox
author_rank: Super Contributor
timestamp: July 11, 2025, 09:25:58 pm
content: My college physics lab had some similar antique meters out of General Electric from approximately that time.Another thing I noted is that the handwritten calibration logs (from GE) were done with a fountain pen in perfect penmanship.

author: radiolistener
author_rank: Super Contributor
timestamp: July 12, 2025, 01:15:52 am
content: Looks awesome - like an elite vintage ammeter from a royal collectionHow much it cost?

author: Micke
author_rank: Regular Contributor
timestamp: July 25, 2025, 09:17:47 pm
content: Upps, sorry for late replyI paid a whopping 60 Euro, which I think is a real bargain considering age and condition!
3D Scanners under $1000? Software? - Page 1
Forum section: electronics / general

author: incf
author_rank: Frequent Contributor
timestamp: July 12, 2025, 10:53:55 pm
content: I recently learned that several low end / consumer grade 3D scanners exist for $300-$800 (eg. Revopoint MetroX, Revopoint Inspire, Creality CR-Scan Ferret, and some other more consumery products). That is cheaper than I expected.I was wondering if anyone had any insight or experience with devices in this space and price range.I also was wondering if any 3D scanners exist that do not require software subscriptions or cloud services to export the point clouds into a format that can be consumed by other software? (eg. FreeCAD)My interest in is creating a 3D model of various suspension components taken from a vehicle to within an dimensional accuracy of 0.25" / ft (roughly 6mm / 300mm), and angular accuracy of +/-3 degrees. While I'm sure that with enough care I could perform the measurements by hand, the components I wish to measure are curvy and have holes/faces at odd angles, and I suspect a tool might do a better job.sidenote: I've read that reference markers "make or break" a 3D scan on large components. I need to learn more about those requirements and constraints.This is for non-commercial use.

author: unseenninja
author_rank: Regular Contributor
timestamp: July 13, 2025, 02:16:07 pm
content: What does 3D scanning have to do with metrology?A far more appropriate section of the forum would be:https://www.eevblog.com/forum/3d-printing

author: wraper
author_rank: Unknown
timestamp: July 13, 2025, 02:24:02 pm
content: Quote from: unseenninja on July 13, 2025, 02:16:07 pmIt has nothing to do with 3D printing. I say put it intoOther Equipment & Products

author: incf
author_rank: Frequent Contributor
timestamp: July 13, 2025, 02:25:13 pm
content: It's about measurement of angles and distances within a specified tolerance. Besides, search showed the last topic on this from 2017 was in this board.The components to be measured have planes at odd angles with respect to one another.Metrology people are the only ones that use this class of expensive metrology tools (handheld laser scanners + accompanying software) that this thread is concerned with.
Recommendation for a power logging tool - Page 1
Forum section: electronics / general

author: drakejest
author_rank: Regular Contributor
timestamp: July 06, 2025, 03:45:54 pm
content: Hello,I would like some recommendations for a power logging tool mainly used for logging the power consumption of a single/3phase home/appliance/building. I have looked around and it would seem that a "Power Quality Analyzer" is the tool that does the job, i have also used one before but i could not remember the brand. I would like to buy one Can you recommend a good brand/model? I need to record days to weeks worth of power consumptioni know they get quite pricey, and im willing to spend upto 2000$ any suggestions?

author: Furna
author_rank: Frequent Contributor
timestamp: July 06, 2025, 04:29:56 pm
content: Latest EEVBlog video on You Tube is indeed a review about a Power Meter ...Dedictaed threadhttps://www.eevblog.com/forum/blog/eevblog-1693-uni-t-ute310-power-meter-teardown-practical-demo/

author: drakejest
author_rank: Regular Contributor
timestamp: July 09, 2025, 02:34:52 am
content: I do not think this records, also it doesnt look like it can do 3phase

author: EEVblog
author_rank: Unknown
timestamp: July 09, 2025, 02:53:25 am
content: Quote from: drakejest on July 09, 2025, 02:34:52 am3 phase loggershttps://www.fluke.com/en-au/product/electrical-testing/power-quality/1732-1734https://www.hioki.com/sg-en/products/pqa/power-loggersUnder your $2k budget:https://www.mitchellinstrument.com/lutron-dw-6093-three-phase-power-monitoring-datalogger-load-study.html

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 11, 2025, 03:20:27 am
content: Just saw the product video of the HIOKI PW3365https://www.hioki.com/sg-en/products/pqa/power-loggers/id_5798And from the brocure of the power logger:https://www.hioki.com/sg-en/download/32970It claims an accuracy of:Voltage : ±1.5% rdg. ±0.8 V (combined accuracy with PW3365-20 + PW9020)And a few limits:*Shielded wires cannot be measured. The product may not be able to accurately measure multi-core cables or cables that have thick insulation.And that seems quite impressive for a non-contact voltage measurement. I'm not sure how they do a non-contact voltage measurement. It's probably capacitive, combined with some wizardry. I also guess that the waveform (for harmonics analysis etc) is captured more accurate then the absolute voltage.
L&N millivolt potentiometer 8686 - resurrected - Page 1
Forum section: electronics / general

author: trobbins
author_rank: Frequent Contributor
timestamp: July 08, 2025, 05:59:04 am
content: I've managed to resurrect the use of the switch/resistor assembly from an L&N 8686 millivolt potentiometer that I picked up for a few dollars recently at a sale. Fortuitously I am part way through restoring a complete L&N 8690 millivolt potentiometer, so quickly realised the maker of the switch/resistor assembly as L&N, and then the 1972 catalog narrowed the original equipment model down to the 8686. I hadn't been able to find an on-line manual for the 8690, but returned to google with enough vigour to locate a schematic of the 8686 as part of an ebay listing, which then made it a lot easier to consider what to do with the assembly.The main slide-wire and pot adjustment assemblies were missing, but the schematic gave enough detail to substitute in an equivalent resistance with fine trim for each of the adjustments, and I used a 10T helipot 7286 L.25 with turns count dial to recreate the slide-wire. The 8686 has a 1.010 to 1.020 range for Weston cell voltage measurement, and a zero to 100mV switchable setting in 1mV and 10mV steps, along with the 1mVFS helipot adjustment. So I'm just resurrecting the EMF output function of the original 8686 equipment, as all the other modes of operation are of no use. Once the adjusable sections were set up for the levels shown on the schematic, then the assembly exhibited output levels consistent with the original catalog spec of +/-(3uV and 0.03%), except for the 00.00mV setting.The 8686 uses one battery current path to configure the 1mV steps, and a separate current path to configure the 10mV steps, with the required output voltage as a difference between two nodes in the different paths. Afaik the 0mV output wasn't trimmable (except as part of the slide-wire portion), so I ended up adding 33 milliohm to the 5.025Ω R1 in the 10mV step path to trim the output down to a few uV difference.The switch/resistor assembly is now on the rear panel of my DIY voltage reference instrument case, and powered from an external 5-12Vdc isolated supply that goes through a temp compensated LM317 set for 1.5V. This makes a nice functional addition to the 0.1V, 1V, 10V, 100V and 500V references that are all derived from a REF102 10V base reference, as the floating 8686 circuitry can be connected in series if needed (well perhaps not the 500V supply). The 100V and 500V supplies each use a cheap ebay smps with input 12Vdc level varied through a FET and feedback loop which seems to function quite well once overal tempco is NTC compensated. This is all DIY, with no attempt to achieve low ppm levels on all outputs, but enclosure temperature control and enough judicious tempco control seems to achieve repeatable confidence below 100ppm in general, so I'm happy.If anyone has the schematic of the L&N 8690, or the full manual for the 8686, then I'd welcome a PM.Ciao, Tim
Cal lab pricing for Keithley 2001 - Page 1
Forum section: electronics / general

author: reef.pi
author_rank: Contributor
timestamp: July 05, 2025, 07:18:56 pm
content: Hello,Apologies if this is not the right section fo the forum, got a question about some metrology lab.Last year in November I received a calibration quotation for a Keithley 2001, about 210 eur + VAT. I forgot about it back then.This month I sent another email asking for the same, and they gave me a quote of 500 eur + VAT.That's more than double the initial price over 6 months period of time.When I questioned why the huge jump, they said first quote was to calibrate it as 6 1/2 not 7 1/2 digits.I was puzzled. I would expect a cal lab to calibrate at the equipment specifications not less?They say to be ISO/IEC 17025 accredited, both quotations specified some national stamp certificate of calibration.There was no reference of such 6 1/2 nor 7 1/2 in neither of the official quotations.I have no experience with cal labs, is this common practice?

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 05, 2025, 09:26:27 pm
content: Not all sales droids know their 2000 from their 2001. It happens often.Even I make the odd mistake as many things go by many names, though I maintain a better than 95% probability of being right.Labs with low uncertainties do have to spend lots of money to maintain them so they tend to charge a good fee for the kit and the time. If you are doing a 2000 you can just rely on the Fluke calibrator, a 2001 will possibly need a 8.5digit meter or better to go with it.

author: bdunham7
author_rank: Super Contributor
timestamp: July 05, 2025, 11:26:40 pm
content: Quote from: reef.pi on July 05, 2025, 07:18:56 pmYou need to discuss and verify each and every parameter and expectation that you have before you start. That includes the cal lab scope of accreditation (their capabilities) and the exact procedure that they will follow (what data is supplied, what threshold for adjustments, etc). "Some stamp..." isn't sufficient, a cal lab could be accredited with very high uncertainty and still take on your work.

author: Cyclotron
author_rank: Unknown
timestamp: July 06, 2025, 01:42:06 am
content: I was able to get my 2001 calibrated for about 300 USD but only due to talking with the Lab and explaining it was a personal instrument for my hobby.I told them I didn't require a certification though they did provide one. I only wanted to be assured that the meter was accurate after I had repaired it.
Tinsley 3504 temperature test article temperature / current level - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: July 07, 2025, 06:37:26 am
content: HelloAn interesting article on a Tinsley resistor 3504 temperature test with details and data .RegardsOS

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 07, 2025, 04:38:59 pm
content: What did you find interesting about it? Other than that, it has been 11 years since it was published.I personally like to look at the uncertainty details and then try to work them out, as each article shows them in different ways.I get a k=2 of 4.8 µΩ/Ω not 5. But I don't like how they have explained the uncertainty for the Bridge,QuoteThough they explain it in Table 6, there are no values, and so it's hard to see how they got to the 2.3 µΩ/Ω value, and against the recommendations, they are calculating an uncertainty and then importing it again, causing rounding issues.

author: Overspeed
author_rank: Frequent Contributor
timestamp: July 08, 2025, 05:31:46 am
content: Quote from: mendip_discovery on July 07, 2025, 04:38:59 pmHelloI will try to be accurate in my answerWhat did you find interesting about it? Other than that, it has been 11 years since it was publishedThere is a lot of article on lab resistor stability versus time but very few on the current level effect as the calibration power level is 10 mW and ...that it , but when you use a resistor as a shunt to measure current value that a true concernThe article age is not really a concern as standard resistor is not a 21 century technology and technical facts stay technical facts so 11 years or 25 years where is the problem even some post war articles are able to provide valuable information.Though they explain it in Table 6, there are no valuesI agree but also not in table 5/4.... That just table to display what type of uncertainty they have ( A or B ) , this article have been written by a well know metrology lab and published in Elsevier so I suppose that not 100% junk . Values are displayed in fig. from graphs.National Institute of Metrological Research (INRIM)Corresponding author. Tel.: +39 011 3919336; fax: +39 011 3919448.E-mail addresses: f.galliana@inrim.it (F. Galliana), e.gasparotto@inrim.it (E. Gasparotto).1 Tel.: +39 011 3919425; fax: +39 011 3919448That fully possibe to drop them an email and request more information.My goal is to built and try a setup as the setup in picture with 10 x 1 ohm Vishay or Alpha in // so 0.1 Ohm and warmup / control the temperature in an enclosureI link a similar setup pictureRegardsOS
Guildline 6675A repair help - Page 1
Forum section: electronics / general

author: dcmxx
author_rank: Contributor
timestamp: June 19, 2025, 10:50:26 pm
content: Some time ago a picked up a really cheap Guildline 6675 DDC Bridge on eBay.When it arrived i tried to test it. But it doesn't work well if i try to measure ratios above 1. This instrument stucks after the Rough ratio passIf i try to measure ratios below 1, the instrument works well.I asked Guildline directly for the service manual, and I got the technical manual for it,also available on xdevs, but got no help in to point out the problemI'm starting to measure supply voltages as show on the technical manual, but it seems fine so far.Does anyone have any experience repairing this units?

author: chinapp
author_rank: Contributor
timestamp: July 03, 2025, 07:36:28 am
content: maybe it's good working, if the ratio >1 ,then swap ti
Diecast Enclosed Banana Plug Terminal Block - Page 1
Forum section: electronics / general

author: laichh
author_rank: Regular Contributor
timestamp: July 01, 2025, 04:17:27 am
content: I normally used Keysight 34171B for quick connection to the DMM for precision measurement, however, no simple equivalent available for a more generic connection. The Pomona 4892 has a really bad insulator (Polyphenylene Sulfide) that makes it unsuitable for any measurement beyond MΩ measurement. So I came out with my own DIY version using only off-the-shelf material expect the PCB.Bill of Material:Enclosure: Hammond 1550PBK / 1550ABK / 1590HBKPCB: Custom, 2 layer, 1 oz Cu, ENIG, 3 mm thickness, countersunk PTH at 4 corners for assembly into the diecast enclosure**Banana Plug PTH Pitch: 19.05 mm (3/4"), 22.23 mm (7/8" for Keysight 3458A), 25.40 mm (1" for Fluke 5730A)Banana Plug: Stäubli 22.1053 / Schützinger FK 1210 AU (not shown)M4 Washer: Stäubli 22.6511M4 Nut: Stäubli 22.6509Ring Lug: TE Connectivity 323152-2 (not shown)Cable Gland: Adam Tech CG-M-M10-1Of cause, for less critical connection, e.g., Guard terminal & current measurement, Nickel/Zinc plated banana plug/washer/nut may also be used.
Symmetricom SyncServer S100 - can anyone help with most recent firmware? - Page 1
Forum section: electronics / general

author: cherokeesix
author_rank: Newbie
timestamp: May 27, 2025, 03:49:31 pm
content: Hello -I have a S100 that has an older version of the syncserver firmware for this model: 2.90.4Does anyone have the most recent firmware for this?Does anyone have any image of an oxco equipped version? It's not silkscreened on the board, I am making the assumption it might be attached to the header (P3) that is also used for the rb?Thanks!Dave

author: ZL4JY
author_rank: Newbie
timestamp: May 27, 2025, 10:41:43 pm
content: Hi there,By sheer chance I powered one up today after fitting a new GPS module (GT-8736D from eBay seller test_tool). It has 2.90.70.7 and while I could read the card, you’re already ahead of me!So I’m also interested in an update.I’m guessing the S200 firmware won’t work.The pinout of P3 would also be interesting.

author: 8bit
author_rank: Newbie
timestamp: June 22, 2025, 01:42:05 am
content: Let us know if you find it.I have a S100 without the CF card... I installed the S350 software but it has issues as it blocks on the Display.I was able to change the startup so it now boots. It should not be too hard to find the differences if I have the S100 software.Some of the S200/S300 have on-board mini OCXO, but many have an off-board device that sits in the empty space.As for the off-board OCXO or RB, yes it connects on P3 and JP3 needs to be bridged. You can then use in-os diag commands to change the NVRAM settings.Here's more info...https://www.eevblog.com/forum/metrology/symmetricom-s200-teardownupgrade-to-s250/100/
A standard or generic I2C temperature sensor? - Page 1
Forum section: electronics / general

author: LM21
author_rank: Regular Contributor
timestamp: June 18, 2025, 12:46:58 am
content: I hope this is a correct forum.We need a new temperature sensor IC. Old from Maxim is getting rare and expensive. We don't need ultimate accuracy but there are good ones with reasonable price. Are there something with several manufacturers and good specs and price. This is an IC, that is around room temperature. Our current sensor uses 5VIs TMP117 used much?

author: Smokey
author_rank: Super Contributor
timestamp: June 18, 2025, 01:41:47 am
content: I've used TMP1075 a bunch. Several packages. Cost is good.If you are concerned about multiple sources, you could make a dual footprint for two packages.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 18, 2025, 01:57:41 am
content: Quote from: LM21 on June 18, 2025, 12:46:58 amYou have not mentioned package, or actual 'good enough' numbers.Take a look athttps://lcsc.com/products/Temperature-Sensors_585.htmlIf you sort by stock numbers, you get a rough indicator of popularity.SOT563 looks popular, as does DFN6.

author: FiveFiveFive
author_rank: Contributor
timestamp: June 18, 2025, 08:00:49 am
content: As PCB.Wiz says, you don't mention package requirements, accuracy or application.We recently needed to monitor an internal enclosure temperature and went with an LM75 in a SOIC-8, ±0.5°C, which was good enough for our application. Compatible devices at a glance are Maxim LM75, Microchip TCN75, On-Semi NCT75, TI TMP275, Maxim MAX7500 and I'm sure a host of others if I were to do a deep dive.It's not a glamorous device in an exciting package, but it's pretty much a 'jellybean' I²C temperature sensor with multiple manufacturers.

author: LM21
author_rank: Regular Contributor
timestamp: June 18, 2025, 03:40:47 pm
content: InterestingLM75 looks good, widely fabricated and inexpensive. The package is largish, so we'll see.