hybridfree/eevblog-posts huggingface dataset:
Optical versus Magnetic isolation for sensors - Page 1
Forum section: electronics / general

author: julian1
author_rank: Frequent Contributor
timestamp: February 24, 2021, 07:53:33 pm
content: For sensors (ie high bit-depth adc,dacs) running in isolated noise/power supply domains, are optical isolators preferred over magnetic isolators or vice versa? I am interested in noise immunity, more than HV isolation.For example, comparing datasheets for two similar options for spi,opto isolation (ACSL-6410-06TE)https://au.mouser.com/datasheet/2/678/AV02-0235EN_DS_ACSL-6xx0_2018-08-21-1827365.pdfInput-Output Capacitance 0.7pF. at 1MHz.Low Level Supply Current 4.6mA typ 7.5mA max.Input Threshold Current 2.7mA typ. 7mA max.magnetic isolation (ADUM4151)https://au.mouser.com/datasheet/2/609/ADuM4151_4152_4153-1503566.pdfCapacitance (Input to Output)1 CI- O 1.0pF, f = 1 MHzQuiescent Side 1 CurrentIDD1 (Q) 2.9 mAQuiescent Side 2 Current IDD2Q) 6.1 mAInput Current per Channel 0.01uA typ +1μA max.The key characteristic of coupling capacitance, appears similar for both (0.7pF vs 1pF at 1MHz).One thing, that stands out is the higher drive/pulse power for the optocoupler. eg. (pulsed 7mA), which is perhaps more likely to introduce noise in the sensor domain. Although maybe it's not an issue just driving an open-collector pull-up resistor placed right next to the chip.
Where to find DMTD board / module? - Page 1
Forum section: electronics / general

author: nctnico
author_rank: Super Contributor
timestamp: February 19, 2021, 03:35:59 pm
content: I want to do some tests with phase noise measurements combined with a time interval counter. See what it can do. I was thinking somebody would offer DMTD modules for this purpose but my Google-fu doesn't come up with anything. Is there anything out there that is reasonably priced? Or is it not worth the trouble? I did order a few AD831 mixer boards from Ebay which I think can be used to cobble something together but a readily made solution would be more convenient.edit: I have found the DMTD board thread but I'm wondering is there is something else out there. In that thread some have suggested to use the LTC6957 to shape the incoming signals which I think is a very good idea. I have seen this device being used in other high performance / low phase noise time distribution equipment.
Escort EDM-3150 - Page 1
Forum section: electronics / general

author: l3VGV
author_rank: Contributor
timestamp: February 14, 2021, 04:53:45 pm
content: I got one broken before new year, and had fun fixing it. Since there is no service manual available, i spent some time drawing schematic. Its only part of analog board, but most important one!Full kicad project and images on githubhttps://github.com/l3VGV/edm-3150*Specs fromhttp://bbs.38hot.netEDM-3150 Digit Dual Display Bench DMM200`000/20`000/2`000 count selectableMulti-display, dual digit plus analog bargraph0.01% basic DCV accuracyDCV,ACV,DCA,ACA, frequency, capacitance, temperature, diode continuityTrue RMS AC voltage, 20Hz-100kHz measurement bandwidthAC current measurement bandwidth from 20Hz to 10kHzFrequency measurements up to 1MHz, 0.01Hz resolutionResistance measurement up to 200MΩ, 1mΩ resolutionTrue RMS(AC, AC+DC)Direct dBm readoutRelative calculationDynamic recording(MIN/MAX/AVG)Measurement rate selectable(5 1/2 - 2.5/sec, 4 1/2 - 15/sec, 3 1/2 - 80/sec in DCV function)Backlit LCD displayAuto or Manual, comparator calculationHI/LO/PASS direct readoutFast electronic calibrationPeak hold(positive negative)Data holdRS232 interfaceGPIB(IEEE-488) interfaceList of SCPI commands same as for ESCORT 3136A it seems. Most of them worked fine, tested with ar488 GPIB-USB converter and putty.This thing have LM299 as main VRef and LM399 for resistance measurements current source. How cool is that!No 4W though.But, can do capacitance. And, it have to be connected to A and mA terminalswhat were they thinking...Screen is pleasant too look at. Continuity is fast and loud, but not annoying.Good device imo.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 16, 2021, 08:05:15 am
content: The circuit with a 2nd LM399 ref. for the ohms current source is odd - quite complicated and expensive way to add more noise and drift.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: February 16, 2021, 03:06:09 pm
content: I know about a dozen benchtop multimeters with a second voltage reference for ohms measurement.
RV722 KVD - Page 1
Forum section: electronics / general

author: niner_007
author_rank: Frequent Contributor
timestamp: February 03, 2021, 04:46:57 am
content: I’ve snatched one of these things from eBay recently (it’s my second one), has been years for it to show up in the listings, these are very rare. I like them for the compact form factor, it’s 1/2 the size of an 720A.

author: TiN
author_rank: Super Contributor
timestamp: February 03, 2021, 05:29:05 am
content: Nice box, hopefully it was cheap.Benefits of 720A are self-calibration and ability to produce DC linearity better than 0.1ppm.

author: niner_007
author_rank: Frequent Contributor
timestamp: February 05, 2021, 10:34:14 am
content: Yep, these were cheap.I have a few 720A. The most recent one from ebay was in like new condition, original label still attached, no scratches, no decay, and only about 10 years old, should post some pics at some point.

author: Echo88
author_rank: Frequent Contributor
timestamp: February 05, 2021, 11:19:28 am
content: That would be nice niner_007, would be interesting to see how more recent units are constructed.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 05, 2021, 04:25:36 pm
content: I also have an RV722 or similar, because I haven't found a good deal on a 720A. They're pretty decent, though no equal of the 720A. On that last photo, I think they trimmed the resistors using an abrasive electric drafting eraser, then coated the area.
Fluke 5700A worn out right VFD - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: July 29, 2020, 09:25:11 am
content: Hello,I have a Fluke 5700A with a very dim right VFD. Rejuvenation procedure of the manual has no effect. Any solution ? Thanks

author: bbqws60
author_rank: Newbie
timestamp: February 04, 2021, 08:11:20 am
content: Can only be replaced with new ones

author: jfphp
author_rank: Regular Contributor
timestamp: February 04, 2021, 12:00:34 pm
content: Thanks but apparently no longer supplied by Fluke !

author: Haasje93
author_rank: Contributor
timestamp: February 04, 2021, 01:45:29 pm
content: Maybe something on Ebay?
Algebric solution of a LISN impedance - Page 1
Forum section: electronics / general

author: BelgianEngineer
author_rank: Contributor
timestamp: January 30, 2021, 10:23:46 am
content: Hey all,I am currently building a DIY LISN. But first, I would like to calculate the expected theoretical impedance curve algebraically so I can later compare my built performance with requirements from the standard (attached pic).The ideal circuit is pretty simple, so it should be easy, right? Well, I've spent already an afternoon on it and I can't get a resulting curve which is similar to that displayed in the standard. So first question:For the impedance curves given in the standard, is the power supply usually assumed to be a short? Is the displayed curve really matching the displayed circuit?If you feel like doing some easy maths, mind having a doublecheck at my calculations (attached pic)? The Laplacian s is converted to frequency domain by s = 2*PI*freq.Seen the simplicity of the circuit I have the feeling that I am missing something basic...

author: Andreas
author_rank: Super Contributor
timestamp: January 30, 2021, 11:11:47 am
content: Mhm,if you are looking at the other threads which handle from the 5 uH LISN: the coil is usually separated into 4 or more individual coils with additional resonance dampening measures. So its definitely no "beginners project".Besides this: you will find more experts in the "RF, Microwave, Ham Radio" section for this theme than in the "metrology" section.although most of the "LISN" threads are either in the "Test equipment" or "Projects, Designs, and Technical Stuff" section.with best regardsAndreas

author: BelgianEngineer
author_rank: Contributor
timestamp: January 30, 2021, 11:31:14 am
content: Hey Andreas,Thanks for the input. Currently the built is a problem for later. I would like to start from the theory here so I can compare performance with the standard even in the case where I decide to buy a LISN. Also, let's be honest, I am driven by my curiosity here. Not being able to manually calculate that impedance curve from a basic RLC circuit is driving me crazy.I'll post the question in the test equipment partBr,

author: BelgianEngineer
author_rank: Contributor
timestamp: January 30, 2021, 02:22:08 pm
content: Seems like I forgot how to do complex Algebra. Problem solved. Thanks for the inspiration!
Fluke 332D faulty decade trimmer  - Page 1
Forum section: electronics / general

author: valley001
author_rank: Frequent Contributor
timestamp: January 25, 2020, 05:13:08 pm
content: Hello all,Its been a long road with this beast but yesterday I decided it was time to try calibration. I only have a 6.5 digit meter so I know I can not calibrate to its specifications just wanted to see if I could get it close...and I wanted to try out the Fluke 845AR I have repaired.It turns out there is a problem with the Decade A #1 trimmer pot. When I arrived at that pot in the calibration scheme I found it did not have sufficient travel to zero out (by around 500uv). At first I feared a defective matched resistor (or several) but I found if I applied pressure between that pot (R47) and the PCB the output (10v range dial setting 1.000000) would jump close to where it should be. Applying similar pressure to other pots had no effect on output so I think I have it pinned to R47.It does not appear that CTS Corp makes this resistor any longer, can I use any 100K 20% 1/2 watt pot in this location?

author: valley001
author_rank: Frequent Contributor
timestamp: January 25, 2020, 11:42:03 pm
content: Update- I re flowed the solder joints I could get to on R47 and added a bit of my own solder, that seems to have done the trick for now.

author: View[+]Finder
author_rank: Unknown
timestamp: January 24, 2021, 08:25:40 pm
content: I have the same issue with my 332D so when I get a chance, I'll try the reflow trick and see if that helps.
HP-8648C calibration - Page 1
Forum section: electronics / general

author: opabob
author_rank: Contributor
timestamp: January 23, 2021, 09:41:02 pm
content: Hi guys. I got an HP-8648C on eBay that seems 100% functional, and I would like to have it calibrated. I placed some RFQ's with several calibration labs; just a standard calibration w/o data. (I don't need data, and I certainly don't need an accredited cal). I've gotten two replies back. One for $240.00, and the other for $1235.00. I double checked the RFQ and yes everything is the same, apples to apples.So why such a big difference in pricing? I can understand some, but this to me seems way too much. Either one is a rinky-dink lick-n-stick cal lab, or the other one is way WAY over priced.Thanks. Stay safe.

author: Villain
author_rank: Regular Contributor
timestamp: January 24, 2021, 03:58:51 am
content: One has an automated procedure for it, the other does not. That is my guess atleast.
Making do with what you got/ Measurement Wires: the Good, the Bad and the Ugly - Page 1
Forum section: electronics / general

author: View[+]Finder
author_rank: Unknown
timestamp: January 25, 2021, 12:17:24 am
content: Hello All,ViewFinder here.My homage to the Spaghetti Western genre is in part prompted by the current appearance of my workstation, but also by a post elsewhere on EEVBlog asking "what kind of wire do you use." I answered and the response from another viewer "that's the worst possible" made me wonder Why's that? More important, how can one evaluate relative suitability on-site?No desire here to reinvent the discussions elsewhere; just perhaps to gather and prioritize parameters such as type of measurement, level of precision and cost for the benefit of all levels of engagement. Sort of a 'cost-benefit' analysis. The balance between $300 for 'wire' and adding $300 to the meter budget, for example.What seems most helpful for readers is a discussion that incorporates the desired level of precision into advice on methods. Perhaps some readers are just trying to avoid making a mistake while others push the envelope on precision. For the latter, Keithley Low Level Measurements Handbook_7Ed, is an excellent resource.Best regards,Donal

author: Vgkid
author_rank: Super Contributor
timestamp: January 25, 2021, 03:06:06 am
content: Just use bare stripped solid core cat-5 cable.Works god for everything not high current/ voltage.
HP VEE 3.0 & 34401A - Page 1
Forum section: electronics / general

author: hnjmkl
author_rank: Regular Contributor
timestamp: January 06, 2021, 03:40:21 pm
content: HP VEE 3.0 with Win95 handles old versions of HP 34401A well but not the subsequent AGILENT and KEYSIGHT versions, I ask if it is necessary to switch to the next versions of VEE and which one can manage all versions 34401A, thank you, Franco
Profile of a surface/point instead of flatness? - Page 1
Forum section: electronics / general

author: raginipaul24
author_rank: Newbie
timestamp: December 26, 2020, 03:47:42 pm
content: So, a customer has asked for the flatness of some of their products to be checked after they were found to be quite bent. Unfortunately their drawing only calls for surface profile. It's a relatively straight edge, so I was thinking of either creating a plane from already programmed points to create flatness, or using the already called out profile for the points to work out the flatness.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: December 26, 2020, 09:47:32 pm
content: Right forum but probably not a lot of people into dimensional metrology! Flatness is always a problem because you need a bunch of points, and you need them in the problem areas. A simple warp isn't too bad, but things like edge roll-off are harder. I think profile means the same thing as flatness, if the profile in question is a plane. Collect your points and see what the spread is. Also, does the surface have any relationship to some other surface that further limits how far out it can be?

author: rubidium
author_rank: Regular Contributor
timestamp: December 27, 2020, 02:08:09 pm
content: Get yourself an optical flat and a cheap 532nm green laser pointer and insert the pointer into a hole made in a ping-pong ball as a diffuser. Observe the fringe pattern and draw qualitative and semi-quantitative conclusions regarding the surface flatness. Photograph the fringe pattern, take the 2D Fourier transform (FFT) of the digital image, and work out the scaling details to get a more quantitative estimate 2D surface profile. The latter is, of course, much more work.
new time master standard? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: December 20, 2020, 02:00:06 am
content: https://science.slashdot.org/story/20/12/19/233227/physicists-made-an-insanely-precise-clock-that-keeps-time-using-entanglement

author: tkamiya
author_rank: Super Contributor
timestamp: December 21, 2020, 04:52:16 pm
content: I saw the original article. I guess in few decades, it will be commercialized and few years after that we'll be able to buy one on eBay! Kind of thinking we are reaching a point of diminishing returns though. How do they tap off and maintain sub femto second accuracy and actually make use of it? Coax alone (hard line) will change dimensions order of magnitudes more with temperature. It may even matter how copper/gold changes at sub atomic level.... I find it fascinating NIST actually did this though. I'd like to learn about this in more detail.

author: jpb
author_rank: Super Contributor
timestamp: December 22, 2020, 10:04:48 am
content: Quote from: tkamiya on December 21, 2020, 04:52:16 pmI guess all such uncertainty will mean that you can't know time/frequency precisely over a short time span but the underlying accuracy will mean the that clock itself never needs adjusting and the average of your measured/utilised values will be correct without long term drift.It might also increase the accuracy of relativistic experiments like they did with the early atomic clocks (flying one around the world while the other stays stationary)https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment

author: coppercone2
author_rank: Super Contributor
timestamp: December 22, 2020, 10:53:33 am
content: if its correct in the long term then can't you parallel it for faster averaging?
DIY EMC Current probe calibration - Page 1
Forum section: electronics / general

author: BelgianEngineer
author_rank: Contributor
timestamp: December 13, 2020, 11:10:53 pm
content: Hey all,I just DIYed a current probe for EMC pre-compliance using a ferrite core and some wiring (based on the webisitehttps://interferencetechnology.com/the-hf-current-probe-theory-and-application/). I would like to characterize it by passing a known sinusoidal current through it and check the response at different frequencies on a scope. However I am a little bit confused by the dB conversion and which p-p or rms value is expected to be used w.r. to a conducted EMI envelope in dBuA:My EMI envelope is given as dBuA (seehttps://docplayer.net/docs-images/68/58959765/images/73-1.jpg) so I am trying to correlate dBm seen on the FFT of my scope to dBuA shown on the envelope. Can someone confirm that the following approach is correct? Note the p-p annotations and remember that I am using a pure sinewave.dBuA = 20*log(Irms)/0.001= 20*log(0.5*Ipp/sqrt(2)) / 10^-6-- I am especially unsure if using the Irms (converted from Ipp) is correct or if I should directly be using the p-p value.dBm = 10*log(Vrms^2/(0.001*R))= 10*log( (0.5*Vpp/sqrt(2))^2/(0.001 * 50) ) <- 50 is for 50Ohm termination and Vpp is the pk-pk voltage sinusoid I see on the scopeWhen I get those numbers on a wide frequency range I can correlate the spectrum seen in dBm on my scope to dBuA from the envelope by adding dBuA - dBm for all frequencies.Any input welcome, I think the approach is correct but I am unable to find absolute confirmation online..

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: December 13, 2020, 11:55:55 pm
content: Hi,Try this:Power = I2RR= 501uA = 1E-6so 1uA x 1uA x 50 = 1E-6 x 1E-6 x 50 = 50 pW (50E-12)1mW = 0dBm0.1mW = -10 dBm...50pW = -73dBmso 1dBuA = -73dBmJay_Diddy_B

author: BelgianEngineer
author_rank: Contributor
timestamp: December 14, 2020, 08:34:19 am
content: Hey Jay,Thanks for the quick answer. Assuming my waveform is a perfect sinusoidal waveform, is it correct to say that EMC envelopes are given in dBuA (RMS) and therefore dBuA = 20*log(Irms)/0.001 = 20*log(Ipp*0.5*sqrt(2)/0.001)?The calibration current is known so what I need to do is to convert that Ipp in dBuA and then correlate this with the Vpp I observe on the scope. Vpp should then be then converted to dBm (in 50Ohm) so I can know the equivalence between dBm seen on my scope FFT and the envelope in dBuA given by EMC compliance.

author: Andreas
author_rank: Super Contributor
timestamp: December 14, 2020, 08:25:30 pm
content: Hello,for me it is not clear where you get a Ip-p Value.All values on the FFT are "energy" values (RMS).so in a 50 Ohms system 0.2236V RMS = 0 dBm = 4.47mA RMSwith best regardsAndreas

author: BelgianEngineer
author_rank: Contributor
timestamp: December 17, 2020, 10:06:59 pm
content: Hey Andreas,The Ipp is my calibration current i.e. the one I am generating and pass through the current probe (basically a siggen connected to a fixed load).
Building a replacement battery for the Wavetek/Fluke 7000/7001 DC volt reference - Page 1
Forum section: electronics / general

author: TheSteve
author_rank: Unknown
timestamp: December 12, 2020, 05:18:45 am
content: I recently acquired a Wavetek/Fluke 7001 DC reference. The battery in it was 21 years old so it was overdue for a replacement.The factory battery is made out of 10 NiMH AA cells.The battery in mine was made of 1200 mAh Varta industrial cells. Over the years they have made the packs out of higher capacity cells with the newest being over 2000 mAh in capacity.Having had extensive experience with Sanyo(now Panasonic) industrial NiCad and NiMh cells I decided to use the Panasonic BK200AAP. This is a cell with a flat positive top(ideal for spot welding) with an average capacity of 2000 mAh and rated for 1900 mAh minimum.Battery data here:https://industrial.panasonic.com/ww/products/batteries/secondary-batteries/nickel-metal/models/BK200AAPYou will want to avoid higher capacity cells as to get that capacity the cells use thinner insulation between plates which makes them far less robust.Before assembly verify the cells are all of equal charge and appear healthy.The battery is held to the back panel of the reference with two bolts. Once they are removed the battery can be unplugged and removed through the side of the casing.The battery has plastic caps over each end and the cells are glued together. There is also a temperature protection fuse that will open should the battery reach 70 degrees Celsius.The plastic caps can be popped off and reused, if they don't want to move then you can apply some gentle heat from a hair dryer etc.I took the new cells and glued them together in the same configuration as the original pack. As the mounting bolts go through the battery pack between the cells you can't have any glue in the middle of the pack. I used new tabs between the cells but reused the original thermal fuse and the battery lead tabs. They can be removed carefully from the original pack.If you don't have access to a spot welder you can also buy AA cells with solderable tabs preinstalled, or if you're feeling very adventurous you can solder directly to the cells but this is never recommended and to be done with caution. Given the value of a 7000/7001 DC reference you want to use a properly built battery pack.Once assembly is done verify the polarity at the connector - outside two wires(black) are negative and the inside two wires are positive(red).It is also a good idea to add an updated date code to the battery pack.Here are a few pictures of the build:The original pack:The new cells:Cells spot welded - thinner tabs on the lower cells go to the thermal fuse which needs to be installed in this location to not interfere with the mounting bolts.Cells spot welded second side:Completed pack with updated date code:New pack installed in the 7001:A happy reference with his Fluke friends:
Timing information from MSF ("Rugby") etc. - Page 1
Forum section: electronics / general

author: MarkMLl
author_rank: Frequent Contributor
timestamp: December 09, 2020, 12:46:49 pm
content: Can anybody provide chapter and verse on whether the timing information provided by the UK NPL on MSF is considered to be a secondary, tertiary (... and so on) or /what/ standard?They provide useful information at e.g.https://www.npl.co.uk/products-services/time-frequency/msf-radio-time-signal/msf_time_date_codewhich includes[quoteThe carrier frequency is maintained at 60 kHz to within 2 parts in 10^12....The timing of these edges is governed by the seconds and minutes of Coordinated Universal Time (UTC), which is always within 0.9seconds of Universal Time (UT1),...this second marker is transmitted with an accuracy better than +-1 ms.but I've never been able to determine where these figures fit in their overall calibration hierarchy.MarkMLl

author: jpb
author_rank: Super Contributor
timestamp: December 10, 2020, 10:16:32 pm
content: The NPL guide might tell you - I don't know because I didn't want to enter all my info to download it:https://www.npl.co.uk/products-services/time-frequency/npltime/productI think from what you put that MSF is based on primary sources but there is a lot of uncertainty in making use of it with the second markers only being within +-1ms and though the frequency is maintained at 2 parts in 10^12 the various receivers (I have an quartzlock one) are only accurate to something like 10^-9 I think or worse so the question as to what the source is, is an academic rather than practical one.I'm not sure why you're asking the question.

author: MarkMLl
author_rank: Frequent Contributor
timestamp: December 11, 2020, 08:41:24 am
content: Thanks for the link, I'll follow it up (something I might have done already, but I'll check) and report back.Updating: that PDF covers a time standard delivered by fibre. It does however state explicitly that"Several countries operate radio signals providing access to aUTC(k) time scale. Both accuracy and traceability are below MiFID IIrequirements apart from voice trading."which implies that MSF is better than one second but says nothing more definite.The "MSF signal technical data" link goes to the same document from which I quoted earlier.I don't think that there's much point in my having another attempt to ask them directly... I tried early this year without response and the COVID-related lockdown is unlikely to have made them more communicative.The bottom line for the moment at least appears to be that the leading edges are reliable to +-1mSec i.e. roughly 3ppm, but it's not at present possible to ascertain whether the NPL- as the UK's statutory standard- is prepared to call this secondary, tertiary etc.MarkMLl
Burster MIKROMAT Kompensator 9303, mV Standard? - Page 1
Forum section: electronics / general

author: HighVoltage
author_rank: Super Contributor
timestamp: December 06, 2020, 02:06:15 pm
content: ThisBurster MIKROMAT Kompensator 9303was a bargain but I can not find anything about this standard? It seems to be a DC mV standard reference.I can only find info's to a similar device, the "Burster Mikromat 3401 DC-Standard".Has anyone here seen such Model 9303?Maybe someone has a user manual?

author: The Soulman
author_rank: Super Contributor
timestamp: December 06, 2020, 04:20:55 pm
content: Try sending Burster a email?They were very responsive when I asked about my Digistant 6425T.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 06, 2020, 05:16:59 pm
content: Quote from: The Soulman on December 06, 2020, 04:20:55 pmYes, I have done that already and they replied that this instrument is not known to Burster.They asked for pictures, LOLMaybe they still find something.All switches were stuck from bad grease and some contacts slightly dirty.After cleaning and greasing it seems to work well.Here is a first test.

author: Greybeard
author_rank: Frequent Contributor
timestamp: December 09, 2020, 03:53:00 pm
content: Nice old stuff, I like it:Here you can find some info:https://www.mikrocontroller.net/topic/263461https://www.amplifier.cd/Test_Equipment/other/Burster-6401-DC-Standard.htmlMaybe forum member "branadic" has more info...BTW, it looks like a more simple version of the Burster Digistant:Here is the schematic of a Digistant "Typ 6401":
Looking to get a frequency instrument cal'd? Look no further! - Page 1
Forum section: electronics / general

author: jlake
author_rank: Contributor
timestamp: November 29, 2020, 05:28:35 pm
content: Up to 12GB?This would not fill me with confidence!

author: The Soulman
author_rank: Super Contributor
timestamp: November 29, 2020, 05:58:20 pm
content: I'd PASS

author: Theboel
author_rank: Frequent Contributor
timestamp: November 30, 2020, 10:46:44 am
content: UKAS ?I believe it's a native English speaker.not a java English like me

author: Oldtestgear
author_rank: Regular Contributor
timestamp: December 04, 2020, 11:23:01 am
content: Apart from the obvious error & that is a bizarre one to make, the company is actuallu fully accredited with UKAS (number 8239) Pity that they did not check their website for mistakes before launching it.Their prices do not seem excessive but their overall capabilty may not meet the expectations of the more committed user (read Volt or Time nuts). That said I have no affiliation with the company & will continue to use Keysight for my DMM calibration. Frequency? That I use a GPSDO for as I am only using my calibration equipment for personal use.For the benefit of the many international users of this site, UKAS is the United kingdom Accreditation Service.FWIWPhil
Meatest P-110X calibrator - looking for info - Page 1
Forum section: electronics / general

author: rolkinas
author_rank: Contributor
timestamp: December 03, 2020, 01:47:58 pm
content: Hello,I am looking for info about Meatest P-110X AC-DC calibration source.Schematics would be very useful while unit contains some burnt resistors inside and 100V, 1000V ranges aren't workingHere are some pictures from inside. Interesting mix of components made in western, eastern and soviet countries.Components labeled "Tesla" has nothing in common with company making electric vehicles. more about it here:https://en.wikipedia.org/wiki/Tesla_(Czechoslovak_company)Meatest is existing company. Still making pretty serious equipment.https://www.meatest.com/products-multi-product-calibrators-145We got reply from them about P-110X. Unfortunately only user manual and specifications, with no service info.Please contact me if you are from that era who have printed service information or owns such unit.

author: rolkinas
author_rank: Contributor
timestamp: December 03, 2020, 01:52:44 pm
content: Foto and manual
The Navicom RCGD-M GPSDO unit - Page 1
Forum section: electronics / general

author: tecophil
author_rank: Newbie
timestamp: November 27, 2020, 02:17:23 pm
content: I have just received this GPSDO unit - found some info on this site re connections to the CON 4 and CON5 connectors and a hint at the RS232 interconnections between the PCB's - has anybody got more data regarding this facility ? thanks
Symmetricom 1050A - Page 1
Forum section: electronics / general

author: notfaded1
author_rank: Frequent Contributor
timestamp: November 14, 2020, 05:50:16 pm
content: I recently acquired a few of these quartz oscillators. There was debate about what oscillator was being used in them. I posted to timenuts but thought I'd also post here since I also had no idea what the LO was in these later model units. I can confirm they contain the 1000B LO. I've powered them all up in MNL time constant setting to see where they settle at. I'm hoping at least one will end up being a good one. From what I can tell they all have the 015 option for phase locking to another external frequency reference. What's really better making the frequency of the oscillator be what it wants to be naturally or pulling or pushing it where you want it to be? For now since I can't verify any of the settings of the control voltage I'm going to let them run for a while until they settle in. The manual gives some calculations you can do to set the control voltage wheels to reach the frequency you're looking for ie. 10MHz, 5MHz, 1MHz. The actual output directly from the 1000B is the 5MHz output. The 10 and 1 are derived from the 5. Anyhow experimenting is fun and these are some pretty neat pieces of gear. I have one of Corby's DMTD I'm working on and hoping and can add that to measurement mix to get some data soon. The warm up initial AD looks like it's heading in the right direction as they warm up so far. I think I may need a full sized rack in my lab. I'm not sure what I'm going to do with the gear that doesn't have rack ears right now? Shelves maybe??? I've been debating the best way forward in this respect.Best Regards,Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: November 14, 2020, 05:56:02 pm
content: Here's the pic of them now running... The phase lock alarm is on because I haven't cleared that yet.Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: December 10, 2020, 11:35:32 am
content: Trying to trim these to use with the DMTD device. This is two of them in multiple 8hr runs.Bill

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: December 11, 2020, 06:54:06 am
content: Bill,Your AD plots are basically showing the performance of your 5061B!Once you start testing the Quartz against each other with the DMTD setup you should see performance below 1X1-12 from 1 to 100 Seconds (AD)Look forward to some plots.Cheers,Corby
[SOLVED] Datron Wavetek 4708 AC problem / Fail 2,5,7 - Page 1
Forum section: electronics / general

author: doktor pyta
author_rank: Frequent Contributor
timestamp: May 04, 2019, 04:21:30 pm
content: I wonder if someone had similar problem before.After switching on the calibrator works OK.After say 15min warmup and using HV AC ranges fails start to appear.They are present ONLY on 10kHz and 100kHz frequency ranges. So maybe it is related to HF transformer.When I type 700V 10kHz and press 'output on' sometimes the correct voltage is present and more often I see Fail 2 (for only 0.2s) then Fail 5 and after prressing Reset : Fail 7.First I thought that it is due to some failure in the output protection circuits. I checked them and even swapped main IC with the new ones. It didn't help.Next bright thought was that maybe there is something that triggers these protection circuits...I connected oscilloscope with tek P6015 HV probe to the output and I really saw some spikes exceeding normal levels.Sometimes they occur at turn on and nothing happpens- output is present.Sometimes at turn on they trigger Fail sequence mentioned above.Sometimes they occur during pressing 'output off' and they do nothing or trigger 'Error OL' message.The spikes look like oscillations at frequency in 100kHz range.Below some screenshots.I would greatly appreciate any suggestions from You.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: November 27, 2020, 10:24:58 am
content: That was long ago, but maybe my comment will help someone in the future.There were two issues.1. dead LED section of M3 optocoupler on REF Divider board.It carries 16kHz reference clock for PLL in AC synthesizer.When this signal is not present, the amplitude and frequency of AC are behaving very strange.I think it was damaged by capacitively coupled spikes which occurred during power disconnecting in the moments the instrument detected Fail.I put 1N4148 antiparallel to the LED to avoid this in the future as it happened two times !2. Bias adj. pot R10 on Positive heatsink assy was not set properly. Approx. 3 turns from the place it should be.This caused crossover distortion when PA was not loaded (that's how I tracked it) and caused HF oscillations when HF transformer was connected to the output of the PA.To correct that I just followed Bias adjustment procedure described in the service manual.Update: All problems with bias current was due to leaky tant C7 on positive heatsink. The only one capacitor I forgot to replace...Cheers!
34401A reference design - odd choices - Page 1
Forum section: electronics / general

author: robert.rozee
author_rank: Frequent Contributor
timestamp: November 23, 2020, 02:37:12 pm
content: i've been tinkering with an LM399 reference, with a view to achieving minimal drift while having no real interest in any exact output voltage - i'm happy with simply using the approx 6.9v direct from the device. the circuit i ended up with, it turns out, is very close to that used in the HP-34401A. below is a (simplified) copy of the HP schematic, with the superfluous (for my purposes) bits and pieces removed.U400-A serves only to provide a stable current to the LM399 via R409, while to ensure startup i'm using a 4.7v zener and 27k resistor to +15V instead of R408 and the +5BV supply. and instead of a single AD706, i'm using two LT1001.what puzzles me is the way the buffer U400-B is tapping off the feedback on pin 2 of U400-A (the junction of the 30k/12k857 resistor pair), instead of pin 3 (the top of the LM399 reference). surely this point will be affected by the opamp's input offset voltage? which in the case of the AD706 can be up to 100uV. or are HP doing something clever where the offsets of U400-A and U400-B cancel out?or, are HP more interested in maintaining the relationship between +7REF and +10REF, and simply found through experiment that picking off from pin 2 worked best in maintaining this? i've not delved into the 34401A design to find out where +7REF is used.can anyone offer any more enlightenment?cheers,rob :-)ps: have managed to pick up locally a mid-90's 34401A with just expired (march-2020) calibration, a step up from my 8842A that was starting to produce a burning smell!

author: Dr. Frank
author_rank: Super Contributor
timestamp: November 23, 2020, 04:12:46 pm
content: Key features of both U400 Opamps are their low Offset Drift of 0.2 .. 1.5µV/Kmax(at low bias currents), which contributes about 0.03 .. 0.2 ppm/K relative to the 0.3 .. 1ppm/KmaxT.C. of the LM399. The combined T.C. is good enough for DCV and Ohm measurements @ 6.5 digits and an overall T.C. in the different modes in the ballpark of 1..6ppm/K.These 30..100µVmaxoffsets do no play a role as they are calibrated into their associated modes (VDC, Ohm) and are stable as described.The buffered +7REF from U400-B is used as a reference for the Ohm mode, to create the different stable excitation currents, so the T.C. is also sufficiently low.There seems to be no essential difference if the voltage directly at the LM399 would have been used.Frank

author: Kleinstein
author_rank: Super Contributor
timestamp: November 23, 2020, 04:26:45 pm
content: It is a little odd to take the 7 V buffer from the feedback path instead of directly from the LM399. Usually the offsets of the 2 OPs don't match very much. So I mainly see a slight disadvantage from more effect of bias current (from U400b) also loading the feedback divider.It is a slightly odd decision, but not the only one.
Maxim MAX6250 - Page 1
Forum section: electronics / general

author: Groucho2005
author_rank: Regular Contributor
timestamp: November 16, 2020, 08:33:48 pm
content: I bought 5 MAX6250, most of them are 4.99980 V, 5.00016 V or similar. This one however stays in my Vref box:

author: Andreas
author_rank: Super Contributor
timestamp: November 16, 2020, 08:54:17 pm
content: Quote from: Groucho2005 on November 16, 2020, 08:33:48 pmMAX6250 or MAX6250A?Which package?My MAX6250A (DIP8 package) drifted up +10ppm/year for the first 3 years then around 3-4 ppm/year for the next years.with best regardsAndreas

author: Groucho2005
author_rank: Regular Contributor
timestamp: November 16, 2020, 09:09:15 pm
content: Quote from: Andreas on November 16, 2020, 08:54:17 pmMAX6250ACPA+, DIP8

author: alm
author_rank: Super Contributor
timestamp: November 17, 2020, 09:06:49 pm
content: Assuming the Keithley DMM is within its 1 year accuracy specs since the last calibration, the reference measuring as 5.00000V should be between 4.99982V and 5.00018V. The one measuring as 5.00016V might be between 4.99998V and 5.00034V. So how much confidence do you have in the former reference being closer to 5V, never mind being between 4.999999V and 5.000001V, as the reading 5.00000V suggests?Have you considered selecting for noise, temperature coefficient or long term drift (this will be hard to measure if the figures Andreas gives are representative), rather than how close it initially is to what your DMM thinks is 5V? Actually, if you would expect it to drift up 10ppm/year for a couple of yours, you might want to pick a value about 40ppm or so low, so it will stabilize near the nominal 5V value. Although the absolute value of a voltage reference is rarely important as long as it's within a few percent.

author: Groucho2005
author_rank: Regular Contributor
timestamp: November 17, 2020, 09:30:19 pm
content: Quote from: alm on November 17, 2020, 09:06:49 pmAll good points, some of which I had not considered. I wish I had a newly calibrated HP 8.5 digit meter to check the various Vref chips I have.Apparently Mouser are getting LTZ1000 early next year. I'll give that a try then.
An interesting read - mathematical approach to estimate of errors - Page 1
Forum section: electronics / general

author: IconicPCB
author_rank: Super Contributor
timestamp: November 16, 2020, 09:54:45 pm
content: Stumbled into this article; thought it an interesting light read.https://www.edn.com/a-mathematical-approach-to-estimate-probable-errors-in-a-measurement-task/?utm_source=newsletter&utm_campaign=link&utm_medium=EDNTestMeasure-20201116

author: guenthert
author_rank: Frequent Contributor
timestamp: November 17, 2020, 12:01:10 am
content: I don't know."Probable error of direct measurementsThe probable error, r, of a single measurement of a series, is a quantity in which one half of the errors of the series are greater than it and the other half less than it. For a direct measurement, the probable error can be computed using the formula:r = 0.6745 √ ((v1 2 + v2 2 +⋅⋅⋅ ….vn 2) / n-1)"Sorry, I have difficulties with texts using magic numbers like that. How did they arrive at that formula and where does 0.6745 come from?

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 17, 2020, 12:45:41 am
content: long story...http://www.spcpress.com/books.phpshort story...Quoteif that rings any bells...https://www.spcforexcel.com/knowledge/measurement-systems-analysis/probable-error-and-your-measurement-systemhttps://en.wikipedia.org/wiki/Probable_errorps: we can believe whatever we want, thats why some people hate school, because they cant believe whatever they want... statistics is an science to represent art into numbers, only if i say it correctly, imho... (not directly relating to anything in this thread) cheers.
UNI-T UT61E Resistance not working in manual ranges? This might help - Page 1
Forum section: electronics / general

author: algorithm
author_rank: Regular Contributor
timestamp: December 15, 2020, 04:01:56 pm
content: Had a problem of my ut61 not reading resistance in manual ranges.Found a helpful post from years ago on a topic here where someone listed all the components in relation to resistance reading.I took apart my ut61 a few days ago to finally try to fix it. Tested the transistors, If I recall Q1, Q8, Q5, and Q6 I got short beeps on (although in circuit?) So I figured it was those. Two Y1 and Two 2AH, which I dont really even know how to read SMD transistors stamps. It seemed I saw different stamps on the same alleged components, but can only trust internet images so much. Anyway, I went through all my PCB junk boxes trying to find those parts, but didnt find them. Got pissed off at the thought of needing to order more parts and wait more... At the end of the day I reluctantly put it back together wishing I could have changed the parts I suspected. But upon reassembling I got all the manual ranges working.The only thing I changed inside was the cap position highlighted in photo. While looking for the caps in relation to resistance reading, I lifted that cap up slightly, not even realizing it must have been shorting 1 leg to the components beneath it.There was enough leg length on the cap where it was layed over and shorting I guess? lolCompared the manual resistance ranges previously malfunctioning with my old fluke, it was spot on.Figured I should mention this in case it could help anybody. lol
Low current HF current source - Page 1
Forum section: electronics / general

author: Terry Bites
author_rank: Super Contributor
timestamp: November 23, 2020, 06:07:09 pm
content: I am a lab-less armchair engineer these days of covid. I had a bit of a brainwave regarding my arch enemy the Convenor. So here's one to pump up Mr Howlands tires. R1=R3, R2=R9+R1, same ratios on both Amp channels. Watch out for generator Zo. Assumed to be 0. Mad resistor tolerances or trimming nightmare only you can decide! But worth a go and dirt cheap. Just how stiff it is I'm not sure? Old age?
About 1kV AC option H01 for 3458A - Page 1
Forum section: electronics / general

author: seebeck
author_rank: Contributor
timestamp: October 29, 2020, 02:04:02 am
content: Hi Folks，Does anyone know how to DIY the 1kV AC option for 3458A?Normally, the 3458A's AC voltage maximum range is 750V, I didn't see this high voltage option H01 form the schematic.Thanks a lot!With best regards.From Seebeck

author: TexasRanger
author_rank: Contributor
timestamp: October 29, 2020, 11:51:22 pm
content: I believe the 3458 uses precision voltage divider in the 1kV and 100V Range at the input, so I guess you can get away with putting around 500k and a few Picofarad in series to the Hi terminal. I used to work in a high voltage Lab, and we usually only used the 10V Range and external Voltage divider. Mistaking 1kVpp with 1kVrms is a pretty reliable way to kill these Units

author: seebeck
author_rank: Contributor
timestamp: November 02, 2020, 07:16:35 am
content: Hi, TexasRangerI knows this method for high voltage measurement, I want to DIY the H01 option for my 3458A,.It's like entering the test equipment, becoming a part of it!Thanks a lot!With best regards.From Seebeck.
Optical Singlemode to Multimode Convertor - Page 1
Forum section: electronics / general

author: veedub565
author_rank: Frequent Contributor
timestamp: October 29, 2020, 08:42:26 am
content: Hi,My optical spectrum analyser has a 9/125 singlemode connector fitted. I need to test a fiber source which has a 62.5/125 Multimode connector fitted. With the amount of loss I'm getting in the mismatch the analyser only gets a very weak signal. It's even worse with a 200/240 equipped source.I'm aware there are convertors available which will receive a multimode signal and then then retransmit it on singlemode. The problem then is I will of course be measuring the laser source in the convertor, rather than the actual unit under test.Is there any passive solution available ? I did find something here that might workhttps://news.fibrain.com/konwerter-transmisji-mm-sm,a263.htmlbut I've not been able to find it for sale anywhere.

author: notfaded1
author_rank: Frequent Contributor
timestamp: October 30, 2020, 04:26:18 pm
content: I'm not sure any method you could devise could substitute for an SA with correct fiber interface. Any workaround would perhaps give some data to compare but you'd never know what you are measuring.Bill

author: Kleinstein
author_rank: Super Contributor
timestamp: October 30, 2020, 05:02:26 pm
content: There is no optical way to couple all light from a multi-mode mode fiber to a single mode fiber. It's a physical principle that one can not improve the luminance.So there will always be quite some loss. One can about estimate if from the core area and NA. So going from 62 µm to 9 µm would result in some 2 % transmission if the NA is the same. About the only thing an extra optics can do is to compensate if the NA would be larger with the single mode fiber - however usually the NA is smaller with the single mode and thus another loss factor (AFAIK it with NA²).

author: jc101
author_rank: Frequent Contributor
timestamp: October 30, 2020, 11:04:36 pm
content: You could try a mode conditioning patch lead...https://www.fs.com/uk/keyword/mode%20conditioning&searchSubmit=Search...if it comes with a loss certificate that could help with your measurements. FS are quite helpful, give them a call or email.
Winchester SRE20H13JTC or M28748/8 connectors for Efratom M-100 Rb Oscillator - Page 1
Forum section: electronics / general

author: notfaded1
author_rank: Frequent Contributor
timestamp: October 28, 2020, 07:48:46 pm
content: So I have a couple of these military version Rb's. They are very similar to the civilian FRK-S which I also have one of. They have a Winchester connector on the top of them for all the 20 pins that carry the signals and power. I figured I'd look for the matching connectors to make some cables. Up to this point I've been using my own wires with female aviation crimp connectors for each pin. I found a place that had 6 of the civilian connectors the SRE ones. I asked for a quote for two of them. I was shocked to find out the connectors are $334.75 each so $669.60 for the two connectors that mate to my M-100's. I think unless anyone knows of any other sources for either of these that I may skip this route.This is what it looks like.Bill

author: chuckb
author_rank: Frequent Contributor
timestamp: October 28, 2020, 09:33:19 pm
content: The Mil Spec Part Number M28748/8 crosses to a Vishay MME25-0201P1. They are not in stock at Mouser (12 week lead time) but they are only $65. So that's one step closer to an actual connector.https://www.mouser.com/ProductDetail/Vishay-Dale/MME25-0201P1?qs=%2Fha2pyFadui7UPLq3PhQjPB2oZ1wFBplKknUkToN90rmzWPQA2%252B5rg%3D%3DI sent a PM with other ideas.