hybridfree/eevblog-posts huggingface dataset:
Found a Zener reference research paper with ADI stamp (and 2017 + 2022 date) - Page 1
Forum section: electronics / general

author: 3roomlab
author_rank: Frequent Contributor
timestamp: December 03, 2023, 05:11:50 am
content: The pdf is attachedthe research hails from politechnica university of bucharestand the first page is stamped a ADI logoand the bottom is a date year 2022The first pages describes a zener operated by a charge pump (operating from 3.3v ?)In the last pages there is a table summarizing themthere is also a table which calls the LTZ1000 a TCUBZ (Temperature compensated "U?" burried zener ?)and the 4 new test pieces a TUCBZ ? Temperature "uncompensated" ?I have not seen a 4.7v / 6.1v QSOP reference before. So this is not a product, yet ?** edit added the 4th table TCUBZ / TUCBZok I will let the real voltnuts take over the discussion now
Fluke A40 Shunt Calibration - Page 1
Forum section: electronics / general

author: danielw22
author_rank: Newbie
timestamp: December 08, 2023, 05:22:26 pm
content: Hello EEVblog members, if you could please help me with this question it would be much appreciated. I recently sent some A40 shunts to Fluke for ISO17025 Accredited cal. The shunts came back and the reports only have AC-DC difference in uA/A at various frequencies. Maybe I am not understanding properly, but I don't see how we can use this data. I would have expected a DC resistance value, and then we could calculate the AC value with the AC-DC differences they did provide.When selecting which level of calibration in the online Fluke RMA, the options were:-Calibration, Accredited-Full Frequency Calibration With 5790a-Full Frequency Calibration With 792a-Full Frequency CalibrationWe went with the first option (Calibration, Accredited).Any advice appreciated.

author: mendip_discovery
author_rank: Super Contributor
timestamp: December 08, 2023, 05:43:39 pm
content: Can you share the results part of the certificate?The maths should be fairly straightforward.If you have questions then ask the lab as they should be able to inform you.

author: danielw22
author_rank: Newbie
timestamp: December 08, 2023, 05:51:21 pm
content: Hi Mendip, thanks for the reply. Full report is attached here. I've also asked Fluke but they usually don't reply to any emails from our lab technicians and engineers.*edit, I see page 2 didn't scan, but page 2 is just the list of equipment used for the calibration.*

author: alm
author_rank: Super Contributor
timestamp: December 08, 2023, 06:07:02 pm
content: The Fluke A40/A40A series was designed for use with the Fluke 540B to measure AC currents by comparing them to a known DC current and adjusting the DC current until the RMS value of the DC current matches the RMS value of the AC current (by comparing the voltage across the shunt). The A40 are not specified for absolute resistance, only for the difference between DC resistance and AC impedance. Their resistance is such that with the 90 Ohm resistance of the 540B is parallel, the voltage is about 0.45 V at full load, but since you are just comparing currents, the absolute value doesn't matter. See also the discussionhere. I attached a relevant snippet from the Fluke 1988 catalog.So sounds to me like it was calibrated based on the intended usage and to factory specifications. If you want a different procedure, you should discuss that with the lab in advance.The A40B series is different and is specified for absolute resistance.
Fluke 335A DC Voltage Standard - Page 1
Forum section: electronics / general

author: Periodic
author_rank: Newbie
timestamp: December 12, 2023, 12:14:30 am
content: I have recently acquired a Fluke 335A DC Voltage Standard, partly to relive my days as an electrical standards engineer in the 1990sIt's in quite good condition, the obvious problem being some cooked resistors in the + 35V supply on the current limiter PCB, and most of the plastic insulating "mushrooms" on the lower inner cover being either broken or missing.I've read the threads on here and it looks as if I will need to replace some of, if not most of the electrolytics.Reading through the service manual it recommends using "Circuit Coat" made by Furane plastic Inc to make good any soldering work on the PCBs.If anyone has any recommendations for an equivalent coating, and a suitable solvent for cleaning the PCBs also a source or suitable substitutes for the inner cover insulators I'd be very grateful.RegardsMike A
Ladyheather 6.14 source code - Page 1
Forum section: electronics / general

author: 603tabasco
author_rank: Newbie
timestamp: November 29, 2023, 04:13:53 am
content: I am looking for the Ladyheather 6.14 source code so I can build it on Linux. I found this post (https://www.eevblog.com/forum/metrology/lady-heather-v6-beta-for-windows-exe/) that indicates one should message Texaspyro for the code but I have not heard back and it looks like Texaspyro has not been active since April 2023 or earlier.Does anyone have a copy that I could acquire? All the alternate download links I have found in that thread are broken.

author: bingo600
author_rank: Super Contributor
timestamp: November 30, 2023, 05:49:26 pm
content: https://www.eevblog.com/forum/metrology/lady-heather-v6-beta-for-windows-exe/msg3257200/#msg3257200
PMF Fiber  - Page 1
Forum section: electronics / general

author: veedub565
author_rank: Frequent Contributor
timestamp: November 30, 2023, 07:49:21 am
content: Not sure if this is the correct forum for this, but it is calibration related.Lets say I have a laser source with a PMF adapter fitted. And I use a normal singlemode fiber to measure the output power and wavelength.Apart from the obvious polarisation issues, is it going to cause a problem interfacing a normal singlemode fiber, to a PMF adapter ? I mean, would the mismatch cause me to read a low power level ?

author: PartialDischarge
author_rank: Super Contributor
timestamp: November 30, 2023, 07:58:05 am
content: Normally single mode fibers have larger cores than pmf, but not always so you'll get a larger power level

author: veedub565
author_rank: Frequent Contributor
timestamp: November 30, 2023, 08:01:48 am
content: yes good point, just had a quick look at some PMF fibers and the core is 6/125 and normal singlemode is 9/125. In that case the launch angle would probably be wrong too
How does this Tester output more power than input power? - Page 1
Forum section: electronics / general

author: arnoudvh
author_rank: Newbie
timestamp: November 26, 2023, 06:46:04 pm
content: We recently had our AC power metering unit tested at a test lab which uses a RadianResearch WECO model 2350, which has been updated to WECO 4050X, 4150X and 4330X according to their website.These units can output and measure voltages upto 600V AC and upto 330A (for 4330X model). I can confirm our test unit was actually subjected to 240V AC and "only" 20A - but that is still 4800 Watt.However, the whole test system is powered from a measly 120V plug with max 1500 W power draw. I looked at their patents - I get that you can run a very high current using a transformer at very low voltage - but it seems this system is running at actual high voltage AND high current (way more than the input power).How can they produce upto 198 kilowatts from a 120V/1500W socket?? Does anybody understand what wizardry is going on??

author: Kleinstein
author_rank: Super Contributor
timestamp: November 26, 2023, 07:58:18 pm
content: For testing the power meter the test current does not really have to flow at the same voltage that the voltage sense input of the power meter sees.The 20 A or more test current would only flow with a much lower voltage of maybe some 1-5 V, just to overcome the burden of the power meter, cables and shunt or current transformer.So the power needs would be more like 20 A x 3 V and a few mA at the high voltage. So more in the 60 W range.

author: SeanB
author_rank: Super Contributor
timestamp: November 26, 2023, 08:30:32 pm
content: Yes they use a few transformers, and separate the voltage from the current measurement, by having one transformer, normally a variac driving a regular 1:2 isolation transformer, to get the 230V range capability, with this connected to the input line and neutral, allowing you to drive the line voltage coils, or the internal power supply for electronic ones. Then you have a separate variac, driving another transformer, this one being120VAC to around 12VAC, but with a secondary capable of providing 100A of current. This then is connected between the line input and the line output, with an ammeter connected in series as well. Line voltage and line current are then set to the correct values, and they run the unit with a set current and voltage for a few hours, checking for the analogue units that the faraday disk does the correct number of turns per unit, or the digital one shows the correct number of pulses.

author: arnoudvh
author_rank: Newbie
timestamp: November 26, 2023, 09:34:58 pm
content: Thanks, got it - that all makes sense now!PS: impressed how active this forum is! Fast answers!
6.5 digit multimeter calibration in Tasmania Australia - Page 1
Forum section: electronics / general

author: Nogtail
author_rank: Regular Contributor
timestamp: November 24, 2023, 12:48:28 am
content: I've got a couple of Keithley 2000 multimeters in need of calibration. I haven't got the equipment to do a DIY calibration, and haven't had any luck finding anywhere local that's able to calibrate a 6.5 digit multimeter. Does anyone know of a place that has the required equipment within Tasmania? I'd rather not ship my babies interstate if it can be avoided.

author: gbaddeley
author_rank: Regular Contributor
timestamp: November 24, 2023, 02:58:39 am
content: Where were they calibrated in the past? Does Tassy have ANY cal labs? You’d probably need to fly it over to the mainland, or take the ferry.

author: Nogtail
author_rank: Regular Contributor
timestamp: November 24, 2023, 06:40:32 am
content: Quote from: gbaddeley on November 24, 2023, 02:58:39 amI imported 3 meters from Singapore in non-working condition. They were last calibrated in late 2015 by Keysight - presumably in Singapore. Two of them have only needed work on the digital side and have very similar readings. I only want to get one of these calibrated to compare against the other one. The third meter had some of the analogue parts replaced and reads way off from the other two and definitely needs a calibration.I think we've got a couple of places that do calibrations, but I could only find one that supposedly does electrical stuff and they aren't able to do a 6.5 digit meter. It's looking like Melbourne might be the closest option.

author: bastl_r
author_rank: Regular Contributor
timestamp: November 24, 2023, 10:01:24 pm
content: Do you have a company nearby that sells thermocouples and temperature controllers?Sometimes they have also a calibrationstation.

author: Nogtail
author_rank: Regular Contributor
timestamp: November 25, 2023, 11:32:42 pm
content: Quote from: bastl_r on November 24, 2023, 10:01:24 pmNot that I know of unfortunately. There are a few government scientific/research places and a university near me, so I can try to find out where they get their gear calibrated.
DC capable(or modifyable) 4 in 4 out 24 Bit 192 kSa USB audio solution - Page 1
Forum section: electronics / general

author: Uselesss
author_rank: Newbie
timestamp: November 21, 2023, 09:43:56 am
content: Hello Guys,For the development vibration measurment and controalsystem I need an USB,Thunder Bolt, Ethernet or PCIe Soundcard or DAQ system with following specifications ordered by priority4 Channels in and out , 2 Steroe channels would be okay either.DC coupling, we are going down in the mHz Range and need and offset in the outputs, since this is very uncommon in audio, modifying the soundcard is an option for mehigh dynamic range and low distortion, we don't need mich preamps since with have allready conditiond signalslinux driver avaiablilitylow cost <300€/$Can you sugest such a system?I had a look on the following devices:Behringer UMC404HD,145€,https://www.thomann.de/de/behringer_umc404hd.htmFocusrite Scarlett 4i4 3rd Gen, 158€,https://www.thomann.de/de/focusrite_scarlett_4i4_3rd_gen.htmTascam US-4x4HR, 217€,https://www.thomann.de/de/tascam_us_4x4hr.htmfor the Tascam US-4x4HR i can get the scematics and know already that it uses Cirrus CS4272CZZ chips.If i dind't ne DC i yould easy go with on of these systems.At the moment i tend to the Tascam US-4x4HR because of the scematics availability.Thanks in advance for you help, i will happily provide further information if needed.
New 3458A owner with questions - Page 1
Forum section: electronics / general

author: rhb
author_rank: Super Contributor
timestamp: November 14, 2023, 01:22:46 am
content: In a fit of severe TEA syndrome I bought a 1990 3458A with symptoms very nearly identical to the one that Shamir fixed in his video on SignalPath.What are suitable replacements for the NVRAM? I know from experience with the Tek 11801 that it's often hard to get the right parts and may take months. Purely a EOL support product line with small runs.I don't plan to take it apart until I've received the NVRAM chips. Are there other parts I should order before I embark on the repair?Thanks,Reg

author: CurtisSeizert
author_rank: Regular Contributor
timestamp: November 14, 2023, 06:36:48 am
content: Get DIP sockets. I used the MillMax ones and they worked well. When I did a similar repair earlier this year, all the necessary Dallas chips were in stock at Digikey. Also, wasn't the source of the issue in his repair loose fiber optic cables? It has been a while since I watched that so I may be forgetting something.

author: IanJ
author_rank: Unknown
timestamp: November 14, 2023, 01:27:46 pm
content: If you want to steer away from battery backed NVRams (Cal & Settings) then there is an alternative by way of FRAM IC's.I made a wee YT Short a few months ago.Gerbers attached.https://youtube.com/shorts/Vz6c6m86O4cIan.

author: rhb
author_rank: Super Contributor
timestamp: November 14, 2023, 03:29:41 pm
content: There was a good deal more than a loose fiber and NVRAM. An opamp or two was also bad. and a voltage regulator pair. I'll be installing sockets any time I unsolder DIPs.I encountered a 6 month wait for the NVRAM in my first 11801. The NVRAM will outlast me, but if I can't get it now have a solution.Have Fun!Reg

author: Echo88
author_rank: Frequent Contributor
timestamp: November 14, 2023, 03:45:56 pm
content: Its Shahriar, not Shamir.

author: ap
author_rank: Frequent Contributor
timestamp: November 15, 2023, 06:57:55 am
content: Have you checked drift of the A/D board? Many units have that problem. There is an appnote for that from KS (AN18).

author: rhb
author_rank: Super Contributor
timestamp: November 15, 2023, 02:42:38 pm
content: I've not done anything but power it up and verify it is as described. I'm in the midst of a complete overhaul of my 1530 sq ft shop and constructing a 12' x 16' shielded room for my electronics lab.I don't currently have the documentation and was hoping someone would post the NVRAM part number for current replacements available.Once I replace the NVRAM I'll start investigating what other faults it might have.Have Fun!Reg
Fluke 5700A MFC that is currently on auction  - Page 1
Forum section: electronics / general

author: EE54
author_rank: Regular Contributor
timestamp: November 13, 2023, 12:19:02 pm
content: Thought this might interest some of youhttps://www.directbids.com/laboratory-auctions/fluke-5700a-multifunction-calibrator-power-on-tested-only-y6oo0e6y?fbclid=IwAR0mHWAshKT6FjrJVVCqTkGz0JIU1JfZJCLX8Bd22w9OdKY3JBpD_Hm2yPQ_aem_ASmXfkW8RuaqNNMwlGLmpVTJyYY0CHNNXrWGKaB_BO93JiIssZL6C55_YANUgRyOxQ4
Fluke 732B replacement handle and support arms - Page 1
Forum section: electronics / general

author: volvo_nut_v70
author_rank: Regular Contributor
timestamp: September 23, 2022, 03:09:55 am
content: I recently received a pair of Fluke 732B, both with damaged front posts. The root cause is that the support arms for the handle are extremely weak because of minimal material around the screw hole where the arm is fastened to the handle. One arm will break and with the weight of the battery the other fails and the 732B is on the floor with plastic bits strewn about. I was also missing one handle.From Fluke the handle is $160, the arms are $20 each. The handle screws are $9 each. The new support arms are the same design and material so it will fail again.I had my machinist friend fabricate a new handle and support arms out of aluminum, photos attached.My question is there a want / need out there for the handle and support arms? What are people's thoughts. The handle and arms do not lend themselves to CNC machining (my friend is capable in both) so it is manually machined. He doesn't consider it complex machining.The arms are compatible with the original handle.The aluminum handle and arms could be anodized black, I haven't priced it out and pricing depends on quantity being done.For straightening out a bent post I used a #24 transfer punch inserted all the way down the post hole and gently tugged the post straight.

author: CorporateReference
author_rank: Contributor
timestamp: October 02, 2022, 04:38:54 am
content: Interested if you can match the powdercoating. PM sent

author: alligatorblues
author_rank: Regular Contributor
timestamp: November 10, 2023, 04:59:13 pm
content: I needed just one of the pieces that attach the handle to the unit. When it was all totalled up,it came to $29 and some cents. The stock handle is adequate for all but abusive treatment, like tying it to a car bumper. I cannot imagine what people do to break the handles off 732Bs. I just got a quote on the power transformer assmbly, $1,200. So, I fixed in myself. The only thing is the aluminum box around the actual transformer is riveted together.
R&S FSH3 VSWR bridges - Page 1
Forum section: electronics / general

author: Grubi
author_rank: Contributor
timestamp: May 17, 2021, 11:21:25 am
content: Hello,I was wonder - have you seen FSH-Z3 and FSH-Z2 bridges teardown somewhere?If one have FSH3 with tracking generator, but missing those bridges - is it possible to make own, external bridge andstill have correct measurement? Spare ones are available from R&S, and from ebay, but on crazy prices.Even calibration set cost like 700-1000Euro.I guess for pre-amplifier it will be easier, but for bridges I don't know...

author: Robert763
author_rank: Super Contributor
timestamp: May 30, 2021, 02:01:51 pm
content: Hi,There s nothing "special" about the R&S bridges. You can use a directional coupler, return loss bridge or even a hybrid power splitter / coupler. They just have to be 50R and cover the frequency range you are working with. You do of course have to normalise it with a short and 50R load. I no longer have a FSH3 but when I did I just used a Mini-circuits hybrid for lower frequencies and a HP directional coupler for V/UHF.Even one of the cheap RLBs on ebay work well. You can put one in a diecast box with N sockets at te righ spacing and use a pair of M-M N couplers to connect it directly to the FSH3.Even better use a pair of thesehttps://www.ebay.co.uk/itm/303209389457?and semi rigid coax inside the box to one of thesewww.ebay.co.uk/itm/332052527822?

author: chick0n
author_rank: Regular Contributor
timestamp: November 10, 2023, 09:57:48 am
content: Sorry for digging up this old thread. But here is Service Manual for FSH-Z2.http://manuals.repeater-builder.com/te-files/R&S%20FSH%20CD-ROM/FSH7.10%20(D)/Manuals/Service_Manual_Z2.pdf
New TI's RES11A matched resistor divider network with 1 kΩ fixed inputs - Page 1
Forum section: electronics / general

author: laichh
author_rank: Regular Contributor
timestamp: November 08, 2023, 06:48:21 am
content: Interesting new matched resistor network from TI.https://www.ti.com/product/RES11A-Q1

author: donlisms
author_rank: Frequent Contributor
timestamp: November 08, 2023, 02:50:21 pm
content: Quick scan of the datasheet -- The TC matching looks good; the rest seems kinda normal. What caught your interest?

author: AnalogTodd
author_rank: Regular Contributor
timestamp: November 08, 2023, 06:35:09 pm
content: Looks like TI is trying to catch up to the part LTC put out over a decade ago, the LT5400. Nowhere near as good of matching or TC matching in the TI part, probably only beats on pricing.
Multichannel time series analysis of Vref data - Page 1
Forum section: electronics / general

author: rhb
author_rank: Super Contributor
timestamp: November 03, 2023, 01:59:36 pm
content: Is anyone here doing this? Autocorrelations, crosscorelations, correlated noise removal, etc.I've seen lots of comments about seasonal variation, but have never seen it quantified.Reg

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: November 04, 2023, 03:23:53 pm
content: The math is way beyond me and probably many others. There are some really sharp people here (you included!) but when you look at the overlap between people who can, and people doing references, you probably get a number in the single digits at best.

author: KE5FX
author_rank: Super Contributor
timestamp: November 04, 2023, 04:20:17 pm
content: You might try playing withStable32if you haven't already. It's meant to be a time-nuts tool rather than a volt-nuts tool, but there's obviously a lot of overlap when it comes to the math.

author: rhb
author_rank: Super Contributor
timestamp: November 04, 2023, 04:32:26 pm
content: I can't write the software to do it if I don't have data. If I had received data files 10 years ago everyone would have an OSSW program to do it. No need to learn all the math though that does help.Everyone is using FFTs without understanding them. Not knowing the math will get you in trouble in fringe cases, but most of the time it's just "blow and go".Consider 100 references in a single enclosure packaged such that one may reasonably assume small variations within the enclosure. If the ambient temperature changes, all the references will shift by a certain amount relative to each other. Even without temperature data, given enough data deriving the temperature change from the voltage changes is just an algebra problem.FWIW there's a lot of overlap with the behavior of quartz crystal oscillators too. From a mathematical physics perspective they are all related to well known and reasonably well described phenomena.Reg
Different readings for residual (differential) and leakage current  - Page 1
Forum section: electronics / general

author: dangerousamateur
author_rank: Contributor
timestamp: August 19, 2023, 09:24:58 am
content: Recently I was given the task of doing the anular electrical safety check by my employer.I've been doing this before at a different place, with other equipment ect. but somehow never faced the following riddles.One never stops learning I guessScenario 1:Metrel Multi Servicer MI2170Vacuum cleaner, Class II, mint conditionThere is no PE connection, the device is was placed on a wooden table.The vessel with the filter is made of metal, the rest is plastic.Insulation check against the metal vessel gives fullscale reading.Residual(Differential) leakage current is 0,04mATouch leakage current is 0,65mAPutting the probe on the metal makes no difference.My understanding is that the touch current displayed is the combined value of PE and probe touch current.Now I would like to understand as exactly as possible how this high reading exactly happens?I tested several identical devices, they all showed the same values and are obviously OK/like the manufacturer made them...Scenario 2:Metrel Multi Servicer MI2170Electrical heating radiator, looks like this one:https://i5.walmartimages.com/asr/79ad3433-6e09-46dd-9f6c-2d75a539d0e3_1.dba027773b028baee6caa9f7cd767949.jpegClass I, PE connection is fine.The device is was placed on a wooden table. Absolutely dry.Insulation check gives fullscale reading.Residual(Differential) leakage current is 0,02mATouch leakage current is 0,87mAHeating Elements can cause significant leakage currents, that is known to me. Also I tested similar devices with the same results.But how would you explain these contradicting values?There is no other connection to earth than the PE!

author: dangerousamateur
author_rank: Contributor
timestamp: October 31, 2023, 08:24:29 pm
content: I decided to give this a bump, maybe somebody has some thoughts to this.

author: mzzj
author_rank: Super Contributor
timestamp: October 31, 2023, 09:16:24 pm
content: Best guess your tester is broken on touch leakage current function.Does it also show leakage current even if you don't have any equipment connected to it?when was it calibrated and were the results ok on touch leakage?for giggles you could also try turning the tester plug 180-degrees on the wall outlet to see if it has something to do with phase-neutral order.

author: mendip_discovery
author_rank: Super Contributor
timestamp: November 01, 2023, 07:17:28 pm
content: Do you have a 0.5, 1 and 2 MΩ resistors?https://www.seaward.com/gb/support/download/365/Page 9 shows the readings you should get for a given mains voltage.
WATTMETER IeS ISW8000: HELP ME! - Page 1
Forum section: electronics / general

author: lionelkjh
author_rank: Frequent Contributor
timestamp: October 28, 2023, 11:26:00 am
content: Hello everyone! I am looking for the contents of the PIC16C55-RC/SP microprocessor mounted on an IeS isw8000 tabletop power meter located on the front panel (photo); (its marker is: U1)... Does anyone have it?? Thank you in advance for your research...Wouldn't there be a correspondence with POWERTEK???

author: Simon
author_rank: Unknown
timestamp: October 29, 2023, 08:02:03 am
content: https://www.eevblog.com/forum/repair/wattmeter-ies-iw8000/double posting will just annoy members and ultimately get you banned!
Patek clock setting in HP5061A and HP5065A - Page 1
Forum section: electronics / general

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: October 27, 2023, 09:01:49 pm
content: Hi,I recently installed the Patek mechanical clock into an HP5065A I'm repairing.If you have ever reached in to set the mechanical Patek clocks you know that it is a bit difficult and requires a bit of dexterity especially in the HP5065A!It also requires pulling the top cover and sliding out of a rack if mounted.The glass bezel unscrews to give access to the hands from the front, any one know if it's OK to set these clocks by advancing the hands manually?It sure would be easier!Cheers,Corby

author: edpalmer42
author_rank: Super Contributor
timestamp: October 27, 2023, 09:35:11 pm
content: Find a clock repair forum that deals with Patek Philippe. Post the question along with a bunch of photos of the internal mechanism and any Patek Philippe labels and see what happens. If the HP version is based on a standard model, you might find someone who will recognize it and will be able to make at least an educated guess. But they might need to see the clock in person to be sure.Ed
Calibration of Handheld Tachometers - Page 1
Forum section: electronics / general

author: fmashockie
author_rank: Frequent Contributor
timestamp: October 25, 2023, 02:12:06 pm
content: Here's a video I just uploaded to my channel showing how to calibrate handheld tachometers (commonly used to perform accuracy verification on lab equipment like centrifuges and orbital shakers) using a frequency counter and function generator. Working in my field, (lab equipment engineer) you can save yourself a lot of money by bringing external calibration services in-house.

author: mendip_discovery
author_rank: Super Contributor
timestamp: October 25, 2023, 06:44:23 pm
content: What wave form did you go for?For ages I would just used a LED on the calibrator with at 12V AC and just adjust the frequency to get the RPM I need. I was able to lean on the accuracy of the calibrator. I remember the MD saying back when he started at lab he worked at they would just point the tachometer at a light bulb and just rely on the mains frequency. The lab I worked at years ago has a strobescope that was used for timing car engines and just have it flash at the desired speed but it would make you feel fuzzy at certain frequencies, it was calibrated.I have now purchased the accessory for the calibrator as I wanted to get 17025 accreditation. Which I now have (0.005% + 0.2rpm). Rather than using a sine wave this thing uses a short pulse (thinking it's a sawtooth) to achieve the signal sent to the LED.I am guessing your counter is externally calibrated and well within its specification.I have thought about using a LED powered by a 12V dc source, with a light sensor connected directly to a counter.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: October 25, 2023, 08:55:53 pm
content: The old GR Strobotach displayed a beat frequency against line using a neon bulb. You could set it to way better than 1 Hz. I can't imagine anything that rotates having to be better than a line calibration.

author: fmashockie
author_rank: Frequent Contributor
timestamp: October 26, 2023, 04:53:20 am
content: Quote from: mendip_discovery on October 25, 2023, 06:44:23 pmI used a square wave. 5Vpp. The LED is hooked up to the function generator main output. And then the counter is hooked up the TTL sync output of the function generator (which is also 5Vpp).I'm sure there are a variety of different ways you could calibrate these tachometers as some have mentioned. This was just a method I came up with that seemed to work really well.Quote from: Conrad Hoffman on October 25, 2023, 08:55:53 pmMy old guitar teacher use to say there are many roads to Philadelphia.
ADMX3652 - 6.5digit voltmeter module from AD - Page 1
Forum section: electronics / general

author: daqq
author_rank: Super Contributor
timestamp: October 20, 2023, 07:18:30 am
content: Funny little module from Analog Devices:https://www.analog.com/en/products/admx3652.htmlDual channel, ±0.2 V, ±2 V, and ±20 V ranges, 6.5 digit resolution, a few decent parameters. Just add a board and you're ready to go. Not cheap at 580USD @ 1kpcs, but I can see a niche for it.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: October 20, 2023, 11:10:38 am
content: https://www.eevblog.com/forum/metrology/adi-admx3652-6-digit-20-v-dvm/
Measurement of frequency response (analog bandwidth) of ADC - Page 1
Forum section: electronics / general

author: Sariel
author_rank: Regular Contributor
timestamp: October 13, 2023, 03:52:53 pm
content: Hello,I have got a new A/D converter chip (mounted on the vendor EVB) that I want to verify it's analog bandwidth.I plan to inject sine waves up to 1 GHz from a RF signal generator (calibrated and adjusted before with RF power meter).Afterward I would use the acquisition software that the ADC has to read the amplitude of the sampled frequencies that I swept.This way I would look for the -3dB point.Do I need to use coherent frequencies for this setup to work well? Is it mandatory that I use only frequencies that are integer number of the sampling frequency divided by the FFT length?Thanks

author: Grandchuck
author_rank: Super Contributor
timestamp: October 13, 2023, 03:57:51 pm
content: Have you looked at at Analog Devices AN-835?

author: Sariel
author_rank: Regular Contributor
timestamp: October 13, 2023, 05:19:36 pm
content: Yes. I looked at that.It doesn't imply if the injected frequencies have to be coherent for bandwidth testing.

author: iMo
author_rank: Super Contributor
timestamp: October 14, 2023, 05:05:57 pm
content: With a "windowing function" made before your FFT it does not matter, imho.

author: Sariel
author_rank: Regular Contributor
timestamp: October 14, 2023, 06:14:18 pm
content: What if no window is used (just the default rectangular window)?

author: gf
author_rank: Super Contributor
timestamp: October 23, 2023, 09:28:41 pm
content: Quote from: Sariel on October 14, 2023, 06:14:18 pmYou may experience scalloping loss. Seehttps://en.wikipedia.org/wiki/Spectral_leakageFor single tones with arbitrary frequencies, use a flattop window.
Example 3457A & 44492A GPIB/SCPI programs for reading data - Page 1
Forum section: electronics / general

author: rhb
author_rank: Super Contributor
timestamp: October 12, 2023, 11:34:05 pm
content: I'm looking for an example of the recommended method of scanning 10 ports measuring voltage references using the subject line combination.Have Fun!Reg

author: rcjoy
author_rank: Regular Contributor
timestamp: October 13, 2023, 01:33:59 am
content: There's an example in the manual. See page 360 athttps://www.keysight.com/us/en/assets/9018-05670/user-manuals/9018-05670.pdf

author: rhb
author_rank: Super Contributor
timestamp: October 13, 2023, 03:05:31 pm
content: Thank you. I've been having a lot of trouble of late downloading manuals from Keysight and old age has taken away the ability to read quickly making large scanned documents a challenge.Have Fun!Reg
Unreasonable battery charger - Page 1
Forum section: electronics / general

author: Zyeborm
author_rank: Newbie
timestamp: October 10, 2023, 12:15:41 am
content: Morning all, this does belong here honest 😂.I'm thinking of making a 12s lithium battery charger as a bit of a stretch project for myself. Digital design I can do reasonably well but I'd like to improve my analogue chops.As such I'd like to make it unreasonably accurate in terms of measuring cell voltage and capacity and do so using as few off the shelf modules as feasible without going to the point it doesn't actually get built.I'm focusing on the cell voltage measurement stage at present.What I'm thinking is this would be a nice place to try out making a dual slope ADC.Told you it was unreasonable right?I'm thinking of using a large value flying capacitor (PP or C0G) in a ladder to capture the cell voltage and bring it down to a ground reference, buffer that then feed it into the ADC.I'm hoping that many of the difficulties with dual slope could possibly be avoided in this application.Because our battery voltage is always at least say 2.7 volts we could avoid operation around the zero volt transition that from what I read seems tricky. So instead of a negative reference use a 2 volt reference.Speed is obviously not a huge deal, if I can get 12 stable readings a second it'd be fine. So we can keep the speed of everything down nice and low.10 measurements per cell at 12 cells nets a neat 120 hz to match double the power line frequency here. So I could trigger one reading on going high and one going low to balance that out. 120hz seems low enough that frequency response of amplifiers shouldn't matter too much?It will presumably need a much chunkier cap for the dual slope than is generally used for this kind of thing.I have no fixed design on anything at this stage, and I have no idea about specific parts that would be good for this build.I'm after general advice from those more experienced especially with dual slope and analogue in general.Are there any parts you would suggest for opamps and comparitors? Is it slow enough that I can reuse the same opamps as comparitors?Is it so slow that all those pesky second order analogue effects will render the output worse than the adc of an esp32 with some 5% resistors in front of it 😂Is a MOSFET based ladder and flying cap going to be too leaky to get useful measurements?Thanks so much for all your time, this is my first foray into participating in volt nutting rather than just living vicariously through Marco, hopefully it's a lasting one
New Peltier power driver LT8722 - Page 1
Forum section: electronics / general

author: jbb
author_rank: Super Contributor
timestamp: October 12, 2021, 02:39:40 am
content: For those of us looking for any excuse to try Peltier elements… Analog has announced a new power stage for Peltier devices, theLT8722.- 15V abs max power input (much higher than ADN8835 et al. at 5.5V)- Up to 4A output- 25b DAC inside to turn digital word into voltage reference (<1uV INL quoted for +-13V output range)- coarse current limitingDownsides:- You’d need your own temperature sensor (+ADC) and digital controller.- data sheet missing a lot of min and max specifications, suggests it’s still in flux

author: MiDi
author_rank: Frequent Contributor
timestamp: October 09, 2023, 02:50:33 pm
content: 2 years later and still unawailable...But at least the demo boardDC3145Ais awailable for ~130$.
Agilent 34970A (34401A) linearity adjustment - Page 1
Forum section: electronics / general

author: TizianoHV
author_rank: Regular Contributor
timestamp: October 06, 2023, 05:16:18 pm
content: In a few weeks I might have the opportunity to calibrate my meters at my university cal lab. My Agilent 34970A has really good temperature stability but linearity (negative polarity) is mediocre.I don't have a 3458A so, to check linearity, I reversed the output voltage at 1V intervals and compared my 6.5D meters (HP 6114A sourcing voltage). On the positive Vs negative test my Keithley 2790 has 7uV error (offsets already compensated) but the 34970A has 16uV error. By comparing the two meter for positive voltages (K2790 as reference) they seem to agree quite well, but for negative voltages the 34970A shows some error. The errror seems "linear" and easily compensable by changing the negative voltage gain.On the service manual they says: "The –10 Vdc calibration electronically enhances the Internal DMM’sa-to-d converter linearity characteristic. This adjustment shouldONLY be performed after servicing the A-to-D converter orreplacement of the calibration RAM." with "ONLY" in capital.Can I overwrite the older linearity calibration or this would be useless / worsening?Thankyou!

author: Kleinstein
author_rank: Super Contributor
timestamp: October 06, 2023, 07:55:58 pm
content: The error really looks like a slightly different gain for the positive and negative side. Even though the difference is seem mainly on the negative side one can not say the the linearty is bad there - the problem is that the 2 sides don't fit togehter, not one side bad.It is not really clear how the 2 separate positive and negative 10 V readings are handled. Ideally this should be based on the expected INL contributions that could make a difference for the 2 polarities. At least from my understanding of the ADC the main effect to expect would be something more U² like, though not very large. It is still possible to also get an error more like a separate gain factor - though I don't see a mechanism for this. I don't know how the formare handles and corrects different readings - both versions would make some sense, but of cause only one of the 2 at a time.A different gain for both sides would be the reasier to implement in the software.There is a chance that a new calibration at -10 V could improve things. Unless there is also an offset problem I don't see why it should make things significant worse.Another option would be to manually or afterwards with the data at the PC correct for the error. Some 1.6 ppm for the neg. side is not yet a big difference and in many cases one does not care.
DC Nanovolt Amplifier Model A10 Reverse Engineering - Page 1
Forum section: electronics / general

author: Mickle T.
author_rank: Frequent Contributor
timestamp: September 30, 2023, 08:02:36 pm
content: Perhaps someone may find it useful for researching or repairing an amplifier.I would be very grateful if you could point out errors in the schematic and PCB.

author: TimFox
author_rank: Super Contributor
timestamp: September 30, 2023, 08:44:01 pm
content: What do you mean by "" ?For example, do you not understand why the first block is called "modulator"?The post changed my three question marks into an emoticon.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: September 30, 2023, 08:51:19 pm
content: All reverse engineering was carried out using photographs of the A10 circuit board, schematics of EM benchtop nanovoltmeters, and long-standing correspondence with the founder of EM.I am not sure of the values of some capacitors, the types of transistors of the modulator and the input stage of the AC preamplifier are unknown. The modulator circuit is drawn according to a sketch from a forum member LTZ2000.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 01, 2023, 05:47:10 am
content: The modulator block still looks a bit odd. The 2 transformers are partially wired in parallel. In the phase when M2 is on this would be an odd configuration with only counter-acting turns in the path. So I think there may still be something wrong with the transformer connections.The amplifiers are 2 seprate parts, though they a drawn a little like a differential amplifier.J1 seems to be a relatively low gain direkt path and J2 the path through the modulator.This would suggest that the lower transformer used for J1 should get a non modulated signal and only the signal to the upper transformer should get the modulation. So maybe the pin2 of the lower transformer is not connected.The JFET choice should not be that critical, most likely some low noise types that work well with some 100 µA. Similar the FETs in the demodulator should not be that critical. There are not that many types with a seprate substrate anyway.
Calibration services in EU (preferably NL) - Page 1
Forum section: electronics / general

author: irdc
author_rank: Newbie
timestamp: September 28, 2023, 03:43:58 pm
content: I've just acquired a Philips PM2534 (PM2534/01 to be precise; yes, with the lovely brown front panel and red stripe). Sadly, the unit appears to have lost its calibration data (I may have overpaid...). Anyone know of an affordable calibration service in the EU (preferably in the Netherlands)? Or maybe there's someone here whose Fluke 5700 could use the workout?Also, the unit didn't come with the probe necessary for measuring resistance (told you I probably overpaid...). Is this something I could construct myself or would the mere smell of solder flux induce too many ppm's?
DIY Simplified Power Meter Range Calibrator - Page 1
Forum section: electronics / general

author: gamalot
author_rank: Super Contributor
timestamp: September 20, 2023, 11:27:13 am
content: I built a simplified version of HP 11683A. Since I had a precision programmable voltage source, the voltage source and divider in the cloned calibrator were unnecessary, and all that remained was the front end of the chopper amplifier.All the components were used that I already had, except for the 12-position circular connector receptacle, which I ordered from Digi-Key (It costs an arm and a leg!).I'm happy with the results, but the noise affects the measurements when the power is as low as 1 microwatt. Maybe I can try better layout and shielding next.---There is a mistake in the schematic I uploaded earlier, I have deleted it and re-uploaded the correct one.

author: gamalot
author_rank: Super Contributor
timestamp: September 26, 2023, 07:44:27 pm
content: Update:New version of schematics and two pictures.

author: gamalot
author_rank: Super Contributor
timestamp: September 26, 2023, 07:46:54 pm
content: and a short video.
Anyone here familiar with a Seica Pilot VX flying probe system? - Page 1
Forum section: electronics / general

author: PeterFW
author_rank: Frequent Contributor
timestamp: September 24, 2023, 01:32:14 pm
content: Recently i had the oportunity to work on a Seica Pilot VX.I had a look at the userinterface and a chance to play with it a little bit and the more i think about it the more something bugs me about.And i just remembered why it looked so familiar...That is a spice window in the schematic view, right? Am i right in assuming that this marvellous machine performs a complete circuit simulation on the backend which it then uses to perform offset calculations/compensations on the in circuit test?Like a window comparator, it autoranges (places probes) till is has something as close to the desired value.If not, can someone expain this to me like a toddler?Like, i get the motion stage, i can use all the usual test equipment it has in it on its own. By the way, those linear magnet actuators on the probe heads are super cute! I got a 3D printer, can do embedded C, CAD, CAM, 0201 hand soldering... all been there.I know how a needle test bed works and how to design one, all good.But i can not wrap my head around this, it looks like magic and it makes me feel stupid.
Gossen Metrawatt METRAHIT 2A - Page 1
Forum section: electronics / general

author: ErnestB
author_rank: Contributor
timestamp: September 16, 2023, 09:02:02 pm
content: Would someone here know who are the buyers of these instruments? They cost around 500,- euro and are of a "classic" specification as the most analogue meters from 30-50 years back, that is accuracy class 2.5 and input resistance of 20k/4k per Vot (=/~). They have an interesting model Metramax2, with an amplifier and 10MOhm input R. That model cost about 270,- euro. I understand a high price , as it is a niche market and probably a higher build quality and Q.C., but I was curious who would pay this high price. So if someone has a good idea let me know. PS I like these analogue meters, they are just beautiful, but one can still find enough nicely preserved second hand meters for 1/10th of this price...
Wavetek 9100 calibrator NVRAM backup/restore. How? - Page 1
Forum section: electronics / general

author: Finderbinder
author_rank: Regular Contributor
timestamp: October 15, 2023, 11:10:50 am
content: Device works ok by now. But having his age in mind, internal (Dallas?) battery dies one day. As I understand at least CAL data would be lost, or maybe some other problems would arise?Bearing this in mind I would do NVRAM backup. The questions are:1) how to backup it the simple way? Or any way if simple way do not exist?2) how to restore it from backup?...Any other suggestion to do to ease self life in case of device failing?

author: Testtech
author_rank: Regular Contributor
timestamp: October 18, 2023, 09:24:10 pm
content: I think cal constants are in Flash, not the Dallas chip. I have replaced a few NVRAM chips in these and not had a problem.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: October 19, 2023, 01:16:18 am
content: I just replaced the DS12887 in mine with a DS12887+I would remove the old one and install a socket. They have an estimated 10yr life so it might be a good investment now.The old one caused mine to be locked up and threw 2 errors that I could not access from the front panel. GPIB was also not functioning.The date/time is obviously lost.The installed options might also be stored there but I don't have any on mine so I didn't notice anything.Cal constants are in flash memory like Testtech stated.

author: Finderbinder
author_rank: Regular Contributor
timestamp: October 19, 2023, 08:36:22 am
content: Quote from: ManateeMafia on October 19, 2023, 01:16:18 amOk. Then written above is valid for options backing up.Or it is not critical and options may be restored after the fact?Accordingly maybe new options could be added the same way?

author: ap
author_rank: Frequent Contributor
timestamp: October 19, 2023, 09:05:20 am
content: If you are concerned, you can remove the Dallas RAMs, copy them, and install new ones on sockets.
tinyPFA availability - Page 1
Forum section: electronics / general

author: erikka
author_rank: Regular Contributor
timestamp: July 09, 2023, 03:15:26 pm
content: Many people have converted a nanoVNA-H4 into a tinyPFA by loading the tinyPFA firmware,see:https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.HomepageFor those that are no comfortable with loading new FW there is now a simpler solution.End of this month both Eleshop and R&L will sell pre-configured tinyPFA, ready for use.See:https://eleshop.eu/tinypfa-phase-frequency-analyzer.htmlThe R&L ordering page will be available soon.

author: erikka
author_rank: Regular Contributor
timestamp: August 02, 2023, 05:49:40 pm
content: The tinyPFA is in stock with Eleshop

author: RAPo
author_rank: Super Contributor
timestamp: August 03, 2023, 06:53:13 pm
content: I received mine today. Came in a very nice blue box, works great.As usual excellent service from Eleshop.

author: erikka
author_rank: Regular Contributor
timestamp: August 17, 2023, 07:55:44 pm
content: Now also available in the USA at randl.comhttps://www2.randl.com/index.php?main_page=product_info&cPath=16_16990&products_id=75961

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: September 15, 2023, 09:59:01 am
content: Now also in stock at Mirfield Electronics in the UKhttps://www.mirfield-electronics.co.uk/SJ