hybridfree/eevblog-posts huggingface dataset:
When to use 24 hour or 90 day specs? - Page 1
Forum section: electronics / general

author: danielw22
author_rank: Newbie
timestamp: January 17, 2025, 05:11:34 am
content: Hello, hoping for some collective wisdom here. My question is when can I use the 24 hour or 90 day accuracy specifications for a meter or calibrator?Can I only use the 24 hour accuracy spec for a 3458A only within one day from it being adjusted to external reference standards? Or if I get my 3458A back from Keysight, can I use the 90 day accuracy for the first 3 months and then need to use the 1 year spec after that?

author: Andreas
author_rank: Super Contributor
timestamp: January 17, 2025, 05:45:08 am
content: In principle: yes.but also read the footnotes with the tighter environment specs.with best regardsAndreas

author: CalibrationGuy
author_rank: Unknown
timestamp: January 17, 2025, 12:09:35 pm
content: The answer to your question is slightly more complicated than using the manufacturer's specifications. Those specifications are based on the average expected accuracy of the meters. Your meter or may not meet these specifications exactly. In order to get the numbers for your meter, you need to consider the quality of calibration (ie. the uncertainty of calibration), and you have to determine your meter's drift by comparing two or more successive calibrations. From that data, you can determine which specification is appropriate.Example: Our reference 3458a's last 2 calibrations on the 10V range had an uncertainty of 0.3ppm. According to the calibrations, our meter drifted 2ppm in 15 months. So worst case, 2ppm + 0.3ppm x 2 = 2.6ppm drift in 15 months. According to the datasheet for an option 002 meter, the 90 day spec is 2.65ppm for a 10Vdc measurement. In this case, for our meter, we can use the 90 day spec all year.Of course, the quality of your cables and environmental conditions can affect the readings significantly when you're talking about extreme accuracy calibrations, end measurements. Just trying to give you an idea of how you would estimate your error.This is our experience.I hope this is useful to you.TomG.PS - We used a Fluke 732c to verify the meter's accuracy, and it was within the limits, as expected.

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 17, 2025, 02:14:02 pm
content: HelloTake also in consideration the fact :- To let the 3458A under power as that not at all a instant stabilization- To carefully use the same wiring / clean posts / .... ppm is a very wild little thingA good way is to follow / record displayed value by using a re voltage measurement each month , but you need a real metrology lab voltage reference.RegardsOS
Half bridge circuit for pulse current measurement / calibration question  - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 15, 2025, 08:02:37 pm
content: HelloAs I have progressed on the precision current source I start the next step which is the pulsed mode .I have located a nice article from CERN lab on pulsed current source ( linked) my question is how work the half bridge calibration circuit and in detail why they set a voltage ref+ to the ground ??Thanks in advanceRegardsOS
How to _simply_ compare DC voltage performance of multimeters - Page 1
Forum section: electronics / general

author: Swake
author_rank: Frequent Contributor
timestamp: January 09, 2025, 09:39:14 am
content: Out of curiosity I'd like toSIMPLYcompare the DC voltage performance of some multimeters. I'm not a volt nut and don't intend to become one. It is not about how accurate these DMM are but more about precision in the sense of 'how far apart these meters are from each other'.Now what, how do I do this? What should I look for? What protocol should I follow? Is there some description out there already that I can read/follow?These 2 will certainly be involved: HP 34401A and HP 3457A. I get it that these should best be powered up for some days/weeks in a as thermally stable as possible environment. We'll do our best here. temperature is likely going to oscillate between 18°C and 19°C.Thanks in advance for guiding me.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 09, 2025, 07:31:37 pm
content: The DC performance has multiple aspects:1) absolute accuracy: how far off from the actual value, especially as zero point and scale factor.2) Drift with time and temperature3) linearity4) noiseThe noise part is easy, at least for the neat zero readings. The absolute accuracy mainly depends on the calibration and drift since then.Checking the linearity can be quite difficult for a higher grade DMM. One can still do a few relatively simple tests with not too much effort. Proably the simplest is the turn over test: so use a short time stable reference (this can be a well isolated battery) and measure with both polarities. This also needs a careful zero point.Another simple test is to look at a slowly, smoth changing voltage, like a RC discharge, record it and than subtract a smooth background. The remainder can give an idea about loacalized INL problems (hard INL).For the drift part it is mainly the temperature part that is reasonable easy to check, e.g. by keeping the temperature of the reference constant and change the temperature of the meter (e.g. 20 to 30 C environment in a closed box). One would still want a resonable stable reference, like a LM399. This tends to be the first step in direction voltnut.
Solartron 7151 Test and Calibration software for AR488- early Release - Page 1
Forum section: electronics / general

author: PascalNE
author_rank: Regular Contributor
timestamp: January 09, 2025, 04:18:50 pm
content: Hello, I've recently released some software onto my github for calibrating measuring and data-logging with the Solartron 7151.If youd like to use this software it's athttps://github.com/Pascal-ne/Solarton-7151-TEST-CAL.The software allows you to take advantage of the GPIB calibration procces of the 7151. It also has long and short term data logging capabilities.The software will still have some issues although I have tested it to the best of my abilities as any issues are reported I'll try my best to fix them. It should also be pretty easy to adapt for the 7150 and 7150+ (although I'd need someone to with one of these to confirm that it works) The logging section should also be pretty easy to adapt since its just basic commands so if you want to adapt it to your own multimter it shouldn't be too hard.If you have any questions or issues or suggestions you can either reply to this thread or Email me at pascal@pascalne.com.Lastly, I should say I'm not a software engineer and this is my first project I have released so I apologise if there is issues. I also apologise if I dont fix issues right away I am revising for some A levels.(I have attached the user manual if you would like to know more)
Symmetricom S300 WWVB antenna - Page 1
Forum section: electronics / general

author: lamune
author_rank: Newbie
timestamp: January 06, 2025, 03:21:37 am
content: Hi folks, I picked up a Symmetricom/Microsemi S300 which is working fine. Just because I think it's cool, I want to use the LF radio feature on it also. I just need the antenna. The part number of it was 1520R-LFR60-KIT and I found one picture of it, seems to be shaped like a UFO with a TNC on the bottom. Of course these things are basically unobtanium now but I'm wondering if any fellow EEVbloggers know anything about either buying or building something that might also work.I do know that the BNC has +12v on the output to the antenna which shouldn't be surprising given the length of the cable the original antenna came with.Thanks!
5440B repair - Page 1
Forum section: electronics / general

author: Rax
author_rank: Super Contributor
timestamp: July 09, 2024, 02:55:46 am
content: I kind of stumbled on a 5440B. Repair project, see here:https://www.eevblog.com/forum/repair/fluke-5440b-repair/.I know this is the widest audience for a unit such as that one.Hope for great input from y'all.

author: Rax
author_rank: Super Contributor
timestamp: January 06, 2025, 01:24:27 am
content: Successful repair, seehttps://www.eevblog.com/forum/repair/fluke-5440b-repair/new/#new.Long trek, but happy camper after obstinate and persistent work.
ultra-low noise fully-differential amplifier article + schematic - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 05, 2025, 01:54:18 pm
content: HelloAn interesting article which challenge the INA849 and the INA851 of Texas Instrumentsbut also the LTC6373OPA211 is affordable at that in the 10 Euro per unitRegardsOS

author: TimFox
author_rank: Super Contributor
timestamp: January 05, 2025, 03:11:44 pm
content: The vertical scale on Fig 9 has a typo: it is really "V/rt Hz", not "nV/rt Hz". The other graphs are correct.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 05, 2025, 03:57:56 pm
content: The circuit should not even need very low noise OP-amps like the OPA211. The more relevant part could be the noise of the 12V / 5 V supply. The step from 12 V down to 5 V should be from a reasonable low noise reference (e.g. LM329 or 1N825 maybe with some filter). With a slight change in the resistors a 12 V / 8 V variant should also work. How relevant that reference noise gets depends on the FET and other matching - so one can be lucky, but could also have significant noise from there.The circuit has a somewhat limited common mode range (e.g. good for some +-2 V and some +3.5 V / -5 V max with limitations).

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 05, 2025, 08:08:33 pm
content: Quote from: Kleinstein on January 05, 2025, 03:57:56 pmHelloThanks , does there is a voltage source in 12V with a ultra low noise as in 5 V I agree that can be done with a voltage reference even perhaps with a ref54 but in 12 V ?RegardsOS

author: Kleinstein
author_rank: Super Contributor
timestamp: January 05, 2025, 10:46:38 pm
content: Both the 5 V and the difference from 12 to 5 V are relevant. The 5 V effects the drain source voltage. JFETs are still effected by that voltage.The 12-5V set the current trough the JFETs and depending on the matching part of this come through to the output. One may not have to go super high end with the voltages, but to be on the save side it would be worth using low noise references. E.g. the 12 V as 5 V + 7 V (or whatever exact voltage to use, e.g. could use 5+5 V). A low noise regulator for the 12 V (as 7 V rel. to 5 V) could be an option.
IC voltage reference humidity effect report PDF  - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 23, 2024, 08:09:38 pm
content: HelloAn interesting article with data on the humidity effect on the voltage ref ICRegardsOS

author: Oldtestgear
author_rank: Regular Contributor
timestamp: January 03, 2025, 12:14:29 pm
content: Interesting article that demonstrates how susceptible to environmental factors analog ICs are. When I was at PMI we used to demonstrate that PEM circuits made pretty good strain gauges.Just cannot beat hermetic packages for precision parts. In my opinion anyway.Phil

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 03, 2025, 07:45:33 pm
content: Quote from: Oldtestgear on January 03, 2025, 12:14:29 pmHelloYes but costs are a concern as for example an OPA333 plastic is in the 5 Euro a ceramic one is in the 100 Euro ... a parameter quite important for a ''NASA'' userRegardsOS

author: Victorman222
author_rank: Regular Contributor
timestamp: January 04, 2025, 02:08:01 am
content: An advantage for modern plastic parts is that they typically have copper leads. Hermetic ones are stuck with kovar which has about 40 μV/C thermal EMF against copper. Older plastic parts tend to have kovar (magnetic) leads.
How do DSO calculate the base and top amplitude? - Page 1
Forum section: electronics / general

author: michael2
author_rank: Contributor
timestamp: January 09, 2025, 12:27:39 am
content: I'm trying to understand, how DSO calculate the base and top amplitudes, from where, say, the 10% and 90% thresholds are derived for rise time measurement. I googled around, found that a histogram is calculated. This histogram (should) contain two peaks which corresponds to the base and top. Then, virtually everywhere I can read something like this:"The analysis will attempt to identify the two clusters that contain the largest data density. Then the most probable state (centroids) associated with these two clusters will be computed to determine the Top and Base reference levels [...]"But how are the two centroids are computed? Especially when the signal is noisy? It looks like, everybody is copying the above sentence, but nowhere it is described how it is done.Please, can somebody give me some pointers, maybe documents, standards, code etc., how this is done?

author: ataradov
author_rank: Super Contributor
timestamp: January 09, 2025, 02:44:02 am
content: When you build histograms you will see two clear peaks for square wave. There is no need to compute anything more, just take those peaks and that would be a good guess.If you have a bit more computing power, then instead of just computing histogram, for each new point increase by one the value of all the points between the previous point and a new one. This effectively assumes that signal did not just end up at a new point, but had to transition there passing all the points along the way. This methods deals with small amount of points and noisy data really well.

author: 2N3055
author_rank: Super Contributor
timestamp: January 09, 2025, 07:33:58 am
content: Quote from: michael2 on January 09, 2025, 12:27:39 amBy fitting Gaussian function over the peak.... ??
Looking for a high voltage SMU (1kV) - Page 1
Forum section: electronics / general

author: owiecc
author_rank: Frequent Contributor
timestamp: January 15, 2025, 07:51:19 am
content: Do any of you have a SMU that can reach 1kV level? I’d like to do a simple (remote) experiment but my SMUs only reach 210V. Keithley 2410, 2470 or 2657 models would be ideal.We are investigating switching losses of power transistors and we need to measure the output capacitance in a particular way.I would really appreciate if you can help perform the experiment.PS. I'd need to log the data. I know this is simple on 2470 but no clue how simple that would be on the other models.
Keithley 230-1 conversion to allow for remote sensing? - Page 1
Forum section: electronics / general

author: Cyclotron
author_rank: Unknown
timestamp: November 29, 2024, 01:40:31 am
content: I recently picked up what I thought was a Keithley 230 voltage source. The one I got is a 230-1, which, based on my reading, would have been installed with 2 other components and a PC to do IC testing. Anyway, I would prefer to have a voltage source with remote sensing.If you look at the pictures, you can see the 230-1 has been modified to add wires from the control board to the GPIB board, which I assume are used to allow the intended configuration to control the remote sensing voltages.The hole is there for the remote/local switch, and the Molex connector appears to be just jumpered. I am looking to put in the banana jacks, wiring, and DPT switch to convert this from the BNC connectors to the 5 Bananas, allowing for remote sensing.Does anyone have any experience with the 230-1? Are the modifications I'm considering feasible? I assume they are given the manual for the 230 shows the particular changes to allow the 230-1 function.The unit works nicely and appears relatively young. 1992-1993

author: Cyclotron
author_rank: Unknown
timestamp: December 02, 2024, 08:43:25 pm
content: It looks like I'm just one of many unfamiliar with this sub-model. I have ordered some bits and bobs I'll want to use and test it. If I can confirm that the conversion works, I'll update this thread.

author: Cyclotron
author_rank: Unknown
timestamp: December 19, 2024, 01:15:35 am
content: I've replaced the BNC connectors with binding posts, created the wire harness and installed the switch. Pics attached. I've fired it up and left it running in my lab tonight. Tomorrow I will run some tests and attempt a calibration.

author: Cyclotron
author_rank: Unknown
timestamp: December 22, 2024, 03:13:03 am
content: Other than mislabeling the Sense vs. Output and Common, things worked very well. Calibration (at least as much as my shop can do) went well and it provides very good results in my testing after calibration. It won't be a replacement for my PDVSmini 2 but it will probably get used more for various projects.

author: Kean
author_rank: Unknown
timestamp: December 23, 2024, 05:10:26 pm
content: I only have a standard K230, but thanks for documenting your results.
environmental chamber project - Page 1
Forum section: electronics / general

author: derZockerMP
author_rank: Regular Contributor
timestamp: December 17, 2024, 07:18:04 am
content: Hello, this post is a follow up of this thread:https://www.eevblog.com/forum/projects/environmental-chamber-build-ideaI'm building my own environmental chamber.The project approach was to sweep the temperature from 10°C to 40°C with a 20W max thermal load inside. The chamber itself uses an old styrofoam box with inner dimensions of 40 x 30 x 25 mm to easily fit a Keithley or other instrumentation inside.The Peltiers are four cheap Chinese ones connected 2 in series and 2 in parallel to get the drive voltage to 24V. The cold side heatsink is embedded in the styrofoam top part and isolated with foam around it. Air circulation is managed with a 120x120 mm fan to keep everything at the same temperature. There is a connector at the top for the PT100 temperature sensor.To cool the hot side, a big heatsink handles nearly 200W, assisted by four fans.For the PID control side, a TCB-NE-AH is used, capable of delivering 18A at 24V. The power comes from a MeanWell 400W power supply with active cooling at the back. Another 12V power supply is for the fans. You can control the speed with two potentiometers and switch the fans and controller on and off with a switch. Three status LEDs indicate on state, operation state, or if an error has occurred. The TEC is controlled by a serial port on the back via nice software called TCB-View or a self-made Python script.The settling time of the whole regulation path is around 20 minutes to stabilize to ±0.05°C. The oscillation is rather short, with around two cycles around the set point. Some graphs are coming soon. If you are building your own, make sure not to make the same mistake and choose the PT100 version. Due to long wires and connector resistance, the error is around 7°C off the actual temperature. Self-heating is also a problem. Thankfully, the offset can be canceled out by software. So, please use PT1000 instead.Feel free to ask if you have any questions about the project.Thanks,Stefan

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 17, 2024, 04:08:01 pm
content: HelloNice project , you perhaps need to make a TUS ( temperature Uniformity Survey ) by using 5 sensors ( Pt100 or Thermocouple T ) sensors are fixed on a light cube frame ( no thermal inertia ) one on each corner and one in the center , this type of measurement is in use on AMS 2750 , that allow to check if your internal volume is uniform in temperature as your heating /cooling is on the box lead .RegardsOS
MI 1340A precision divider question  - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 18, 2024, 09:36:07 am
content: HelloMI ( Canada ) propose a 1/10000 divider built by using 1/10 divider in serie with quite impressive performanceQuestion : when the 1/10000 ratio is used ( 4 1/10 in serie ) how the resistor noise is managed ?This sound interesting to generate very low voltage for testing , does someone know what circuit / components they use ?4 circuits with the same design and the same components .RegardsOS

author: Kleinstein
author_rank: Super Contributor
timestamp: December 18, 2024, 10:55:09 am
content: They don't show much details, but chances are this is 1 resistor chain, like 9M , 900 K, 90 K and 10 K. The resistance values may also be lower (like 1/10) - have not found a value.Depending on the resistance there will be resistor noise, but not much to be done about it. The resistor chain is made to start with a high voltage, like 100-1000 V. Starting with a lower voltage (e.g. 10V) one has the choice of high resistance and rel. high noise with the full chain and starting in between with less resistance, but also less divider steps then. So the divider would not be a good solution to go from 10 V to 1 mV.In addition to the resistor noise there may also be thermal EMF at the terminals. There are other dividers for very low voltages: power coefficient and leakage is less critical, but thermal EMF and proper drive sense (quad junctions for steps in between) more important.

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 18, 2024, 01:23:43 pm
content: Quote from: Kleinstein on December 18, 2024, 10:55:09 amHelloThanks for your answer , I search a solution without rocket science to generate 1 mV or lower value with acceptable precision compare to a Ref 54 at 5V so not drowned in noise . most articles / schematics are for HV voltage unfortunately.Do you have a track to follow ?RegardsOS

author: StacysMom
author_rank: Newbie
timestamp: December 23, 2024, 05:36:09 pm
content: The lab I work at has one of these but it is currently out for calibration, so I am unable to get you the actual resistance value of each stage.We have noticed significant noise when starting from the highest stage and dividing down to very low voltages.Once the unit arrives back calibration, I can provide more details.Edit:Just looked back on some of my notes and found that the 5 resistors in series are 4MΩ, 400kΩ, 40kΩ, 4kΩ, and 400Ω.

author: bastl_r
author_rank: Regular Contributor
timestamp: December 23, 2024, 06:03:15 pm
content: QuoteOh yes!We would of course be delighted to receive a detailed teardown.Regards

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 23, 2024, 08:30:41 pm
content: Quote from: StacysMom on December 23, 2024, 05:36:09 pmhelloThanks as any additional informations is useful even if that not for low voltage , the concept to stack 1/10 divider is interesting .RegardsOS
Rigol DG1022Z frequency calibration guide - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: December 11, 2024, 06:56:13 am
content: I have a Rigol DG1022Z function generator I bought new 7 years ago and when I get access to a GPSDO I would like to tweak the frequency accuracy of the Rigol. Don't want to touch anything else, just the frequency. Could someone point me to a step by step guide how to do this?I don't think it has noticeably drifted, just want to make sure it is as accurate as possible.

author: Freddy15
author_rank: Newbie
timestamp: December 11, 2024, 09:54:51 am
content: HiDid that with my DG1062Z last week, see page 2-3 in the cal manual attached.Suggest to use a scope instead of the frequency counter.Plug your reference clock to one channel and the properly configured CH1-out to the other channel.Adjust so that both waves don't move against each other, will result in a mHz accuracy.Cheers M.

author: Circlotron
author_rank: Super Contributor
timestamp: December 11, 2024, 01:11:20 pm
content: Thanks heaps Freddy15.To enter the calibration mode it says to enter the password. Is there a default password for these?

author: Freddy15
author_rank: Newbie
timestamp: December 11, 2024, 04:43:59 pm
content: HiIf you haven't changed itthe standard calibration password is “123456” (see 1-1)Cheers
Philips PT 2248 Ref. Unit, any Manuals? - Page 1
Forum section: electronics / general

author: Wollvieh
author_rank: Contributor
timestamp: January 29, 2022, 06:43:46 pm
content: I've got a Philips PT 2248 Electronic Reference Unit from around the 70s. Nothing to find on the internet about that one. Maybe anyone has old material from Philips? The device and its specs could be mentioned in a catalogue or that good old quarterly magazine which Dave mentions in eevblab 94.At full scale the device is about 3% out. On the inside it contains a shielded box in which I can spot a Zener Diode in an old quartz-like metal package. And there are two trimmers.I would guess one is for zero and the other for the gradient. But I would prefer not to screw around blindly and screw it up. Because 3% out is better than completely warped.

author: Calypso
author_rank: Newbie
timestamp: April 25, 2024, 12:28:27 pm
content: I have two of these.On one of them are the specs.

author: goaty
author_rank: Regular Contributor
timestamp: April 26, 2024, 06:13:42 am
content: Got one just now. Need to carefully try to start it up as its 220V.Anyone knows what it was for ?Interresting bit of kit.

author: Wollvieh
author_rank: Contributor
timestamp: December 08, 2024, 02:05:15 am
content: Thanks for the specs!Didn't see the new answers automatically.I would assume this Unit was used as any calibrator is. With its Millivolt range it could even simulate thermoelements.

author: bastl_r
author_rank: Regular Contributor
timestamp: December 10, 2024, 06:12:54 pm
content: hiWith 6 contacts there are any sensing connections, i think.did you connected them correct?

author: bnz
author_rank: Regular Contributor
timestamp: December 10, 2024, 06:33:45 pm
content: The Copyshop Zwingenberg seems to have the manual. However price on requesthttp://www.rainer-foertig.de/unterlagen/Philips_2010.htm

author: Poroit
author_rank: Frequent Contributor
timestamp: December 11, 2024, 04:48:29 am
content: G'day All,I agree with Wollvieh.It looks like an early model process calibrator.Thermocouples.1-5V DC.0-20mA DC.The 1-5V and 0-20mA were all common Process signals 30 years ago before 4-20mA took over.Philips were very strong in Process Instrumentation back then.
CABLE TESTER TDR :  UNI-T UT685B KIT PROBLEM MEASURING LENGTH ON SHORT CIRCUIT - Page 1
Forum section: electronics / general

author: DiJeFr
author_rank: Newbie
timestamp: December 15, 2024, 11:09:57 pm
content: Hello everyone From France,I have just purchased a UT685B KIT TDR Cable Tester (Time Domain Reflectometry) for €100 from uni-trendlinkshttps://meters.uni-trend.com/product/ut685b-kit/It looks a lot like the FLUKE Microscanner 2 which costs €950.linkshttps://fr.flukenetworks.com/datacom-cabling/copper-testing/MicroScanner-Cable-VerifierIt allows you to test ethernet and coaxial cables. It measures the length and where the open or short circuit is located, and a tracker of cable. It is announced for an accuracy of +-0.6m or +-4%. the measurements on the open pairs of ethernet cables are good. However, the measurements on pair in short circuits are erroneous; it gives almost double the real values, measure 38m on real 20meters . What if there was a bad impedance match on its output that creates two bounces and it measures the second.I would like to know if any of you who have this product have noticed this defect or is it a manufacturing defect in the one I purchased. In which case I invoke the warranty.Otherwise it seems like a good product to me.I hesitate with the Noayfa NF-8601S but this product seam to me dangerous because, if you put an POE on the main entry you destroy the entry of the device, and NVP (Nominal Velocity of Propagation) can not be choice, you can only measure cable to calibrate the product, and NVP is hidden.Thank you for your feedback. And have a good day to all of you from South of France.DJ
Interchange Error Issue in high resistance meter /Interchange Error Issue on Pre - Page 1
Forum section: electronics / general

author: email_removed_by_admin
author_rank: Newbie
timestamp: December 01, 2024, 04:16:23 pm
content: I work with precision resistance measurement instruments based on DC comparator (DCC) bridges, specifically a unit similar to the Measurements International 6010D.I’ve been encountering an issue where the interchange error in is around 0.1 ppm in one unit limit is +-0.02 . I tested another similar unit, and its interchange error is around -+0.2 ppm, which is also higher than expected.Here are my questions:What could cause interchange error to consistently remain high in such systems ?Could this be related to internal components (e.g., magnetic core, capacitors) or external factors (e.g., lead connections, environmental conditions)?What are the best troubleshooting steps to minimize interchange error and achieve more consistent results?Any insights would be greatly appreciated!Thanks in advance!
effect on Rl value on current source : Low R Load versus high value R load - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: November 26, 2024, 08:16:27 am
content: HelloI have with more explanation than Rload value have a effect on the current source circuit as :A voltage controled OP AMP current sourceThe twin JFET circuit as the italian low noise current sourceI my case I need to measure low resistance value ( under 1 Ohm ) with a 4 wire setup so shall I take care of some parameters / calculation ? with a 10 mA source or greater as 20 mAI link a schematic of the Italian low noise JFET circuit but they have tested value starting at 200 OhmsI want to avoid if possible to built a complete circuit for worth results a JFET cost 25 Euro on MouserRegardsOS

author: Kleinstein
author_rank: Super Contributor
timestamp: November 26, 2024, 08:33:18 am
content: For a resistance measurement the circuit makes little sense, as the current is not long time stable and the voltage reference used is the floating battery.The probably use the relatively high resistance to really look at the current noise, more for a shorter time scale. In principle the circuit should be not much effected by the load resistance as the current source part is floating. The main link to ground is the input current of the INA and thus it's input impedance. This should be no issue with the relatively large current, it's more a few pA the go the wrong way there.A precise resistance measurement should have a resistor as refrence element and use the same voltage ref. to drive the current and at the ADC to measure the voltage over the DUT. A ratiometric measurement does not even need a stable current source / voltage reference. In a simple circuit the voltage over the reference resistor is used as the ref. voltage to the ADC. One may still need a buffer, as the ref. input of some ADC draw some input current.

author: Overspeed
author_rank: Frequent Contributor
timestamp: November 26, 2024, 09:42:02 am
content: HelloThanksI have several possible solutions for 10 mA low noise stable source , solutions which are sorted by :A simple precision resistor linked to a precision voltage source , not really stable on 10 mA , work on 1 mA as precision source don't provide enough current .A Jfet transistor with a simple resistor control , not really stable in temperatureA Jfet transistor circuit with voltage control not really stable in temperatureA voltage controlled Op Amp , can be a solution as Voltage control can be from a true precision source ( available at reasonable cost with a precision resistor divider ) that adjustable work nice on 1 mA as the linked circuit ( from this forum )On Github there is this solution also base on two circuits one from direct OP AMP Output the other by using two transistor to increase the current levelhttps://github.com/Strathclyde-EQOP/Vernier-Current-Driver?tab=readme-ov-filethe most complete files set with details explanation I have never see .RegardsOS
Datron 1062 Calibration ended badly . . . - Page 1
Forum section: electronics / general

author: View[+]Finder
author_rank: Unknown
timestamp: November 25, 2024, 01:52:30 pm
content: A Datron 1062 came my way by eBay . . .. {The start of every adventure} In my case this one was part of a purchase of Pomona parts from a seller in the Seattle area, and for a good price. Sadly, the battery was flat and therefore the CAL magic was lost. After replacing the battery and the "usual suspects" elec caps, I began the process of coaxing the meter back to working condition as it had a very good display and was free from any visible damage or "prior work". About two weeks of RTFM and de-oxit, the meter would read volts and amps albeit at the wrong values. So it was time for calibration.Following the script exactly {EXACTLY, means look for decimal point in Ib and voltage setting in Lin}Finally got CAL light ON and self-test to PASS BUT on SAVE 10VDC, the meter failed in what can best be described as a "light-show". No sparks or smoke, just every button on the front flashing randomly.Just FYI, I herd the sound of a relay just as the CAL light came on. Now the relays were buzzing with the lights.NO more reading voltage or anything. Just flicker on the display.Any clue what happened? Is this the dreaded opto-coupler issue?

author: TheDefpom
author_rank: Frequent Contributor
timestamp: November 25, 2024, 08:17:16 pm
content: I’ve done several videos repairing these units, my experience is that:All electrolytic caps have to be replaced.The plastic bolts holding the +/-15V regulators to the heat sinks degrade and break, so the regulators over heat and cause the 15V rails to turn off and on when they get too hot.The two round bridge rectifiers often fail and need to be replaced.ICs need to be reseated in the sockets to freshen up the connections.Tantalum caps like to randomly blow and short out the 15v rails (always replace with 35v, not 25v)The wires on the 5V regulator can be badly corroded by the flux that was used at manufacture, check it isn’t just about to fall off.Check voltage rails, more than once, the last unit I did had tantalum caps blowing and keep on shorting the +/- 15V rails out.You can narrow down faults by unplugging boards, it will run without the resistance, current, GPIB, AC boards plugged in, don’t forget the ribbon cables snd side rail connectors.There are tantalum caps on the front panel between buttons, never seen those fail but there could always be a first time.Some units have the front/rear input switching unit mounted in the back which has relays on it, that has tantalums too which I have seen fail.
Strange measurement error with Datron 1271 - Page 1
Forum section: electronics / general

author: View[+]Finder
author_rank: Unknown
timestamp: November 18, 2024, 08:03:13 pm
content: My Datron 1271--the one with the broken right display--has only options for DCV and ohms. That's ok as it is just measuring a 10VDC reference on the 10V range. However, when measuring on the 1V and mV ranges, the display shows 10x too low. It will correctly measure 10VDC on the 1000v but not 100v ranges.In other words: 10VDC displays as 10.000000 V on the 10V range but displays as 1.000000 V on the 1V range and the 100V range.Without the information from the right-side display, troubleshooting is difficult.1) Any clue as to the 10x too low problem?2) Is there a way to use GPIB for troubleshooting (I haven't found it in the manuals)Any help will be appreciated.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: November 19, 2024, 05:46:58 am
content: Most likely the problem is a faulty relay K204/K205 or a lack of control signals for these relays.

author: View[+]Finder
author_rank: Unknown
timestamp: November 25, 2024, 05:33:50 pm
content: QuoteYes (thanks too) both relays are clicking when I switch from from one mode to another--hard to tell which ones--K204 and K205 (probably) working. Attached is a better version of the readings obtained in various ranges with 10V, 1V and 100mV inputs. The 'orange' readings may simply be re result of over-voltage? 'Red' = 'BAD'.JUST BECAUSE A RELAY CLICKS does not confirm signal passage, however. Time to hook up some wires to nearby test points.BTW: there is a jumper 'A' in the vicinity of the relays; what's up with that? Anyone know?
symmetricom timeprovider 5000 firmware - Page 1
Forum section: electronics / general

author: testpoint1
author_rank: Frequent Contributor
timestamp: February 07, 2024, 10:41:28 pm
content: Hi,my current firmware is 2.1.7, exits the GPS weeks rollover problem, from "FSB098-40621", it said:rel. 4.1.2 will push rollover date to 12/31/2037but I can not find where is it, also no official release, someone has it ?the GPS still is Furuno GT-8031F.

author: testpoint1
author_rank: Frequent Contributor
timestamp: March 21, 2024, 05:00:43 pm
content: the technical support of the company sent to me, thanks.

author: rplabs
author_rank: Contributor
timestamp: November 19, 2024, 12:35:17 pm
content: Hi testpoint1,Do you still have the firmware for the TP 5000? I got one unit and I need the firmware that fixes the Week Rollover issue. I emailed the support of Microsemi and Microchip but no answer.Thanks!
Building an atomic clock with Endohedral Fullerenes - Page 1
Forum section: electronics / general

author: nctnico
author_rank: Super Contributor
timestamp: November 02, 2024, 09:41:42 pm
content: I guess they spend all the money on getting the molecules and forgot to buy decent microphones.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 18, 2024, 04:29:35 pm
content: I really don't care about what their presumed cost of some weird substance is, and that was a slight annoyance. Then came a long shot of some logo with a bluish background and annoying music. That's 3 annoyances and was enough to close close the video.I'm not sure but I think that guy looks like one of the "famous" youtubers. I'd expect better introductions from such people.

author: jbb
author_rank: Super Contributor
timestamp: November 18, 2024, 10:42:43 pm
content: TL;DWCesium atomic clocks are good, and work by probing the behaviour of the unpaired electron. Unfortunately to do that you need isolated cesium atoms and that means a very complicated vacuum chamber, cesium atom source, magnets etc.By jamming a lonely nitrogen atom into the middle of a buckyball (carbon 60 molecule), you can achieve a similar effect but hopefully without vacuum chambers etc. This might open a door to a very small low power implementation. Edit: some modest magnets likely still required.

author: nctnico
author_rank: Super Contributor
timestamp: November 19, 2024, 12:05:21 am
content: It is interesting, but I'm kind of missing the expected performance. How would it compare against Rubidium, Cesium or a Hydrogen maser?

author: coppercone2
author_rank: Super Contributor
timestamp: November 19, 2024, 02:46:47 am
content: there has got to be some better vacuum pump to get rid of the turbo molecular pump.For some reason they made me think of force fields/plasma, I hate the idea of a bucky ball clock, there needs to be a better way to make a normal one.You know that rotating plasma field they make a window with in some youtube videos that looks kind of cool, using magnets? I wonder if that might be the first step to making some kind of 'pump impeller'Also the video makes me feel like I stepped through the quantum mirror . Their laws of physics are just slightly different

author: iMo
author_rank: Super Contributor
timestamp: November 19, 2024, 07:00:26 am
content: ..this is somehow related..
Aricle: A novel precision dc current source in the pA range - Page 1
Forum section: electronics / general

author: r6502
author_rank: Regular Contributor
timestamp: November 19, 2024, 06:19:07 am
content: Hello all,very interesting article:https://www.researchgate.net/publication/220410187_A_Precision_Current_Source_Using_Delta-Sigma_ModulationGuido
Keithley K155 battery holder 3D model - Page 1
Forum section: electronics / general

author: lowimpedance
author_rank: Super Contributor
timestamp: June 24, 2019, 06:51:21 am
content: While cleaning the 'muck' out of a K155 battery compartment I was thinking what to do about holding the small replacement 9V batteries in the now large cavity !.Then ah ha why not 3D print one instead of jamming lots of foam in there.See pictures for the result. And attached in the zip file are the '.STL files for any owners who could be bothered.

author: TheSteve
author_rank: Unknown
timestamp: August 03, 2019, 04:43:22 pm
content: Got a new printer yesterday. Decided I would go with this as my first test print. It came out quite nice and fits perfectly - great job on the design.The sample PLA included with the printer was white - matches nicely in the 155, kind of looks like PTFE

author: HighVoltage
author_rank: Super Contributor
timestamp: August 03, 2019, 05:26:37 pm
content: Nice design, I will try it on my K155

author: Rax
author_rank: Super Contributor
timestamp: November 13, 2024, 11:08:58 pm
content: Old thread, but work that keeps on giving to the community. Thank you, lowimpedance, for making this available!I just got a 155 for myself, in what seems like pristine condition - including internal original batteries that still measure in spec (two of them), and nearly in spec (the other two) - and the 1554 power supply in the back.On a related track, what type of batteries have others been using for this? Just regular alkaline 9V? (which I see in the included pics) Or lithium? It doesn't seem very critical to me, but just curious on others' picks and their reasoning.

author: Rax
author_rank: Super Contributor
timestamp: November 17, 2024, 04:55:39 pm
content: As long as I resurrected this, I thought I'd contribute some images of the finished product.
Fluke 5200A GPIB Card - Page 1
Forum section: electronics / general

author: Tony_G
author_rank: Super Contributor
timestamp: November 15, 2024, 11:24:56 pm
content: Hey All,Just wondering if anyone has every seen this card or if you know of anyone who has recreated it?TonyG

author: picburner
author_rank: Frequent Contributor
timestamp: November 16, 2024, 08:54:33 am
content: I had that calibrator but I sold it and I didn't think to take a picture of the IEEE board.Judging from the schematic the board would not be difficult to replicate the only obstacle is U34, a microcontroller of the MCS-48 family, you would need to have one to extract the code.With the 8051, at least with the old devices, it is quite simple to do probably the thing is also possible with the MCS-48 family.But you have to find someone who has the calibrator with the IEEE 488 card.....Edit: I already had the U34 firmware, fortunately I hadn't deleted everything after selling the calibrator.I'm attaching the firmware here, maybe it will be useful to someone.

author: srb1954
author_rank: Super Contributor
timestamp: November 16, 2024, 10:00:23 am
content: I have a GPIB card in my 5200A. I will take a photo and post it tomorrow.There is a full schematic and component layout in the back of the Fluke 5200A manual P/no 357194 Sept 1975 Rev. 3 5/85. It is indeed based around an 8749 micro and all the GPIB functions appear to be implemented in LSTTL logic. It should be possible to replicate this circuit although 1 or 2 of the GPIB interface chips and old LSTTL chips may be a little more difficult to source these days.The KO4BB site has a copy of the binary file for the 8749.

author: Tony_G
author_rank: Super Contributor
timestamp: November 17, 2024, 01:46:08 am
content: Interesting - I have a 5200 manual that says it is an 8448:U34 IC, 8-bit micro-computer, with EPROM 454876 34649 8448-8CI was primarily wondering because I took my 5200A out of the rack to test an extender board and I noticed that the cover plate I had taped in place said 488 instead of the the typical remote controller TTL stuff - I sort of glossed over that when I first acquired the unit years ago.TonyG

author: srb1954
author_rank: Super Contributor
timestamp: November 17, 2024, 02:57:41 am
content: Quote from: Tony_G on November 17, 2024, 01:46:08 amI popped the label off the controller chip and found it was an Intel D8748H rather than an 8749 as I first thought. The label was "5200A-4086 454652 U34" which must be a different S/W revision to what you have.Attached is a photo of the PCB.

author: Tony_G
author_rank: Super Contributor
timestamp: November 17, 2024, 03:31:10 pm
content: Thanks - Great photo - I don't actually have the card, I just have the cover plate for the slot - Originally I thought it was just the standard TTL remote control card slot as the manual I got from Artek doesn't include the 488 option but checking, the manual I downloaded from Fluke does.
Quartzlock A1000  - Page 1
Forum section: electronics / general

author: Cyclotron
author_rank: Unknown
timestamp: November 11, 2024, 12:40:33 pm
content: I've got one of these that was manufactured last year and the rubidium oscillator won't lock on.I was able to get the attached manual from the manufacturer but have not been able to get support. So I guess I'll explore fixing it myself if it is feasible and economical.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: November 11, 2024, 01:17:31 pm
content: If manufactured last year, surely the 24 month warranty applies. Quarzlock appear to still be in business…email sales@quartzlock.com orTelephone: +44 1444 232 967SJ

author: Cyclotron
author_rank: Unknown
timestamp: November 16, 2024, 01:44:31 am
content: Oh I have tried. I have emailed them but not phoned. The sales email responded and said they needed to get this to the correct department but I have not heard anything since and that's a week or more ago. Anyone considering Quartzlock might want to reconsider as I'm not sure you'll find the support for the product. I also pointed out that the link to the manual was broken but I haven't seen them fix that either.The address appears to be a residence but that could be the case for a company that does small volume and a possibility that they source some parts manufacturing.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: November 16, 2024, 08:37:55 am
content: The address is down a narrow road at the side of a house.This Google Maps image from 2 years ago shows their premises.https://maps.app.goo.gl/z4Vi6qR4iFjTT1Tj6?g_st=icYou can read about them at Companies House:https://find-and-update.company-information.service.gov.uk/company/00708818I have had no dealings with them, but when I worked in the mobile radio industry back in the 1980s and 90s, we used their off air standards to set up quasi synchronous radio systems (using their model 2A, which used 198/200 KHz radio signals).I am surprised they are providing so awkward to deal with.SJ
Alternative to the fluke SMFT-1000 solar PV string tester - Page 1
Forum section: electronics / general

author: drakejest
author_rank: Regular Contributor
timestamp: November 14, 2024, 02:38:31 pm
content: It would seem i have been installing quite a few solar setups lately, and would like to invest on a good tester dedicated for solar stuff, looking online it would seem the fluke SMFT-1000 is the complete package.. Only problem is... well its a fluke and so expensive. I understand that it is worth its price, but installing solar is not my day job yet. So is there like a cheaper equivalent to this tester from other brands or manufacturer?

author: Ugur
author_rank: Regular Contributor
timestamp: November 14, 2024, 02:55:01 pm
content: Seaward PV150 or PV200
Fluke 5500/CAL - MET/BASE 7 - Page 1
Forum section: electronics / general

author: dcmxx
author_rank: Contributor
timestamp: November 12, 2024, 04:02:42 am
content: I own a Fluke 5500A MFC that i got some time ago. The calibrator was repaired with help of one member of the forum, and I posted the result in other thread.Currently the calibrator it's working well. But recently i got a 5500/CAL license disk, and I'm wanting to install the software to use it to control the 5500A calibrator.I haven't found online any installer for the MET/BASE 7 that as I understand is the main part of the software.I tried to contact Fluke Calibration to see if the could provide me the requiered installer, but the claim that this software is no longer supported, so the couldn't help me.I'm looking if someone has the required installer, or any hint to any place where I could get the software