hybridfree/eevblog-posts huggingface dataset:
Valhalla 2730GS - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: October 09, 2017, 08:58:03 am
content: Did anybody see this calibrator ? How many were sold and anything about the customers (Navy...) ? Thank you

author: dacman
author_rank: Frequent Contributor
timestamp: October 10, 2017, 12:01:37 am
content: I believe that the US Navy used the 2720GS (but not the 2730GS). It wasn't very reliable (way back when).

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: October 11, 2017, 01:29:11 am
content: I don't know about reliability but the 2730GS has been obsolete for some time but its introduction had a paper or two at the IEEE:http://ieeexplore.ieee.org/document/10877/?reload=trueby Paul Withers.
Trimble NTPX26AB to Stabilock 4040 - Page 1
Forum section: electronics / general

author: bin10
author_rank: Contributor
timestamp: October 06, 2017, 08:29:45 am
content: Good morning,Sorry my English .. (Google Translator)Please, information.How do I connect the GPS Trimble NTPX26AB BNC 10Mhz standard frequency output (> 2 V-pp to 50Ohms) with Test Set Stabilock 4040 external reference frequency input (> 0.2V to 200 Ohms).I look for information with the Internet, but I did not find it.Thank you.Best regardsClaudio

author: CJay
author_rank: Super Contributor
timestamp: October 06, 2017, 11:17:25 am
content: With an impedance matching pad if you want to be sure of an impedance match but in practice, I think it will probably just work if you plug it in with a BNC-BNC patch cable.

author: bin10
author_rank: Contributor
timestamp: October 06, 2017, 12:48:11 pm
content: Hi CJay,Thank you,That's how I think.Is this impedance matching available for purchase or should I build?can I have more information on how to build it?Thank you.

author: CJay
author_rank: Super Contributor
timestamp: October 06, 2017, 12:55:55 pm
content: Quote from: bin10 on October 06, 2017, 12:48:11 pmYou can buy one from Minicircuits etc. they have them for standard impedances but you may need to build one for 200R input, there are calculators on the web which will work out resistor values, use the closest standard value to the calculation results.It should be easy to build one for 10MHz

author: bin10
author_rank: Contributor
timestamp: October 06, 2017, 01:01:33 pm
content: Thanks for your advice.start the search.
finding the saturation current for hand made toroid inductor - Page 1
Forum section: electronics / general

author: Matter45
author_rank: Newbie
timestamp: October 04, 2017, 08:17:43 am
content: Hey internetAnyone living in the southern highlands or Sydney area who has a 100A power supply I can borrow to determine the saturation current for this hand made toroid inductor? (its quite big)need to know what the left over Henry value is @ 70A.will be using an oscilloscope on a shunt to determine saturation curve.Cheers!Mathew

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 04, 2017, 09:49:49 am
content: Any data on the toroid?Tim

author: ahbushnell
author_rank: Frequent Contributor
timestamp: October 04, 2017, 12:34:30 pm
content: Use a capacitor to pulse discharge into the inductor. Measure voltage and current with an oscilloscope.

author: A Hellene
author_rank: Frequent Contributor
timestamp: October 04, 2017, 12:57:53 pm
content: Though Tim means that the cross section of the core can give the approximate power handling of any transformer, ahbushnell suggests testing the transformer because winding by hand (if not done properly) can result in a quite large leakage inductance --which, generally, is something not good nor desirable.Check this fine solution out:Power Inductor Checker, by Elm-Chan.-George<EDIT>Oops... After revisiting the thread, I am not sure how I ended up with a reply intended for a novice user regarding transformer re-winding issues. I'm sorry, Mathew...Anyway, to anyone interested, the same exactly rules apply either there is a single winding inductor or a multiple windings one, i.e. a transformer or a multiple inductors configuration wound on the same core --for example, the single-core coupled-windings SEPIC inductors.

author: Matter45
author_rank: Newbie
timestamp: October 06, 2017, 03:04:23 am
content: i just slapped myself on the forehead. Why didnt i think of that?Thanks!
Keysight 34465A x Fluke 8845A/SU - Page 1
Forum section: electronics / general

author: ebclr
author_rank: Super Contributor
timestamp: October 05, 2017, 02:55:06 pm
content: What are the pro and cons for each one, planing a new acquisition and is hard to decideKeysight 34465A x Fluke 8845A/SU

author: HighVoltage
author_rank: Super Contributor
timestamp: October 05, 2017, 06:47:15 pm
content: I have a Fluke 8846A and it works well but as soon as you start working with the user interface of the Keysight 34465A you never want to go back to the 8846A.The 8845A and 8846A are really dated instruments in comparison.I am comparing it to my 34470AThe only advantage of the 8845A / 8846A that I can think of, is a much faster warmup time.The 8846A shows stable measurements after only 60 seconds after power upMy 34470A needs at least 15 to 20 min after a cold start, to be stable in the ppm range.

author: dacman
author_rank: Frequent Contributor
timestamp: October 06, 2017, 12:00:30 am
content: The Tektronix DMM4040 is basically a Fluke 8845A in Tektronix colors (and the DMM4050 is a repackaged 8846A). Even the Tektronix manual looks like it's from Fluke. One improvement that was made with the DMM4040 is that it can measure 1000 Vac, where the 8845A is rated 750 Vac max. (I sometimes use a 8846A due to it being able to measure 1000 Vac.)The 34465A and 8845A are both rated 750 Vac max.All these meters can use SCPI remote commands.
What Resistance Standard is this? - Page 1
Forum section: electronics / general

author: zhtoor
author_rank: Frequent Contributor
timestamp: September 27, 2017, 04:31:28 am
content: Hello all,does anybody know about the price / performance of these ?http://etalonpribor.com.ua/mc3050-mc3050m-meri-ielektricheckogo-coprotivleniya.htmlregards.

author: ataradov
author_rank: Super Contributor
timestamp: September 27, 2017, 04:42:42 am
content: All the parameters are listed in the table. Google Translate should handle this well. If you are interested in some specific parameter, I can translate, but the whole table is just too long.Prices are most likely to be extraordinarily high. The only way to find out is to contact them.
Question about voltage regulation for GPSDO and controller + heat - Page 1
Forum section: electronics / general

author: cdev
author_rank: Super Contributor
timestamp: September 21, 2017, 06:42:17 pm
content: I have a precision frequency standard (a TruePosition GPSDO) that seems to work with any supply voltage above around 9v. It has internal voltage regulation. Also, although a number of people, especially @Pigrew and @Texaspyro have done a great deal of work to reverse engineer the device's available commands and meaning of the output message stream, I think its realistic to say that a significant body of relevant information about it's operation, command set, etc. remain little known compared to most other GPSDOs. Because its sold to telecoms as part of a system for locating cellphone emergency callers by TDOA that it appears is EOL.I have a nice STM32F103C8T6 controller for it which was designed by @Pigrew and its soon going into a case with the GPSDO. It generates some, but very little heat. Similarly, the OLED display runs on almost nothing and generates almost no heat. However, voltage regulators do emit heat. And I think the device should have additional voltage regulation given that its going to be powered by a wall wart continuously, 24/7. I may use two voltage regulators, one for 12v (or 9v) and one for 5 volts. If it can run successfully of 9 volts with good accuracy that would be better because going from 9 to 5 volts is likely to generate significantly less heat,enabling a higher degree of accuracy perhaps for the oven. .I don't know if I'm getting across exactly what I want to say, I'm kind of exhausted, but you probably see what I am getting at. Its actually very basic stuff.The GPSDO has a command $TRAINGPSDO which literally entrains the GPSDO when conditions which could impact the performance change. It seems to work.The final form of this device is likely to need one or perhaps two voltage regulators, and my plan is to mount them on the back of the device's case to hopefully have the heat not impact the oven. I want to make sure they don't interact with the GPSDO's temperature control.I just don't want to make a stupid mistake with the power supply that decreases the device's accuracy or life..Does anybody know of a document specifically on GPSDO "hardware integration"
Kohu model 351 voltage standard manual - Page 1
Forum section: electronics / general

author: eurofox
author_rank: Unknown
timestamp: September 20, 2017, 01:11:05 pm
content: I'm looking for maintenance and user manual.Cannot find anything on the netI know it is verry old gear

author: Vgkid
author_rank: Super Contributor
timestamp: September 21, 2017, 12:34:26 am
content: Best of luck, I know what that is like.
Prema 8017 - Page 1
Forum section: electronics / general

author: branadic
author_rank: Super Contributor
timestamp: September 03, 2017, 04:09:46 pm
content: One hour left for this piece of gear:http://www.ebay.de/itm/Prema-8017-Multifunction-Meter-/282622980907?hash=item41cda4732b:g:EPMAAOSw5TZZnoWz-branadic-

author: MK
author_rank: Regular Contributor
timestamp: September 03, 2017, 05:18:49 pm
content: finding it impossible to get google to give me a "tranlate this page" I dont know why they have broken the search in google? is it ebay robot rules???

author: Philipp23
author_rank: Newbie
timestamp: September 03, 2017, 08:52:56 pm
content: HelloTime for my first post here. I bought this 8017 some hours ago. I always wanted to have this great Multimeter with all its additional functions. Btw Prema still offers full service and calibration for the 8017.Kind RegardsPhil

author: 2N3055
author_rank: Super Contributor
timestamp: September 03, 2017, 09:01:49 pm
content: Quote from: Philipp23 on September 03, 2017, 08:52:56 pmCongratulations, hope it serves you well!!

author: branadic
author_rank: Super Contributor
timestamp: September 03, 2017, 09:20:31 pm
content: Congrats to your new device. I suggest that you send it to Prema Semiconductor for service and calibration. I'm sure they will also update the firmware, so that the bugs are gone.-branadic-

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: September 03, 2017, 10:42:41 pm
content: Yup. One week short of WEINHEIM I let it go. Viel Spass damit.

author: Theboel
author_rank: Frequent Contributor
timestamp: September 04, 2017, 12:38:36 am
content: really interested any one has more detail about this particular Type ?

author: branadic
author_rank: Super Contributor
timestamp: September 04, 2017, 08:30:24 am
content: Quote from: Theboel on September 04, 2017, 12:38:36 amIt's at least a Prema 5017 but with integrated 386SX CPU at 25 MHz giving additional functionality . On amplifier.cd are some pictures of the inside:http://www.amplifier.cd/Test_Equipment/other/Prema-8017.htmlManual can be found directly at Prema Semiconductor:https://www.prema.com/index.php/de/service/messgeraetewartung-branadic-

author: nidlaX
author_rank: Frequent Contributor
timestamp: September 04, 2017, 09:15:14 am
content: Quote from: branadic on September 04, 2017, 08:30:24 amWow, that is actually absurd!

author: branadic
author_rank: Super Contributor
timestamp: September 13, 2017, 05:54:22 pm
content: Did you receive your Prema 8017? Would be interesting to know how it currently performs. Maybe you want to try, if you get the extra digit when activating math (ax+b with a=1 and b=0):https://www.eevblog.com/forum/metrology/getting-one-more-digit-from-a-6-5-digit-meter-without-using-gpib/msg1300529/#msg1300529-branadic-
BAOOST voltage regulator and strong magnetic field - Page 1
Forum section: electronics / general

author: sasa
author_rank: Regular Contributor
timestamp: September 17, 2017, 07:43:26 am
content: I have bough several BAOOST voltage regulators in the past, as they have ON/OFF switch pin I have needed.However, I have notice this in datasheet:"( 8 ) When used within a strong magnetic field, be aware that there is a slight possibility of malfunction. "No further explanation nor exact data. What exactly magnitude of magnetic field should be that malfunction? For instance on poles or near neodymium magnets.Strictly theoretical question, if anyone have experience with or made any research.

author: Assafl
author_rank: Frequent Contributor
timestamp: September 17, 2017, 08:09:35 am
content: I have never used these devices - but it is possible that one or more of the transistors and/or a resistor are dimensionally long enough for hall effect to be pronounced.An example hypothesis would be that the current sensor would read incorrect current given a large enough magnetic field and possibly turn current limiting off (or let the device overheat).I would take a neodymium magnet and touch the device and see what happens....

author: sasa
author_rank: Regular Contributor
timestamp: September 17, 2017, 08:38:59 am
content: Sorry, I have missed to insert datasheet link:http://www.mouser.com/ds/2/348/rohm_BA00ST-SFP_Series-316518.pdfI do not have any neodymium magnet, I would certainly perform such test myself .
Communicating with Beamex units (MC6/MC5) via USB - Page 1
Forum section: electronics / general

author: Libbstick
author_rank: Newbie
timestamp: August 13, 2017, 09:46:40 pm
content: Hi guys,Been subscribed to EEVblog on youtube for awhile and just found out there was a forum!I am just curious to know if anyone has had any previous experience with communicating with Beamex units such as MC6 and the MC5 via usb or other means?I have pdf copies of the protocols for the communications I just have very entry level knowledge of the processes and know-how!Bit of a stab in the dark but hopefully there is someone out there!

author: zhtoor
author_rank: Frequent Contributor
timestamp: August 26, 2017, 09:56:41 am
content: Quote from: Libbstick on August 13, 2017, 09:46:40 pmhello,could you please link the pdf file for the protocols for beamex MC5/MC6 comms protocol ?regards.
2x Fluke 732A - Page 1
Forum section: electronics / general

author: LapTop006
author_rank: Unknown
timestamp: August 17, 2017, 02:52:26 pm
content: Just feel like showing off some new acquisitions.One is missing the battery unit (this was one of those eBay bids you don't really expect to win, and it tipped over Australia's 1k point where a heap of duties are due), so I ended up buying the second (I think this is also one of the ex-ADF units that all came on the market at once).I plan to have a mate clone the metalwork for the battery unit, and the board's pretty trivial.The 196 here probably hasn't seen a cal in over a decade, so this was more getting lucky when I turned one of the standards on that it started a touch low and came up as it heated up. The other one is far enough out it might end up as a parts unit.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: August 17, 2017, 03:10:04 pm
content: Some seller on eBay (with the coke can in the photo) was selling 732a battery packs and 732a's as separate pieces a while back. I'm not sure how much a lone battery pack would sell for but you might check to see if it's still for sale.

author: LapTop006
author_rank: Unknown
timestamp: August 18, 2017, 01:36:54 am
content: I did look for 732 battery packs, but none were available a few weeks back.Given how simple it is cloning seems pretty sensible.

author: texaspyro
author_rank: Super Contributor
timestamp: August 18, 2017, 04:35:30 am
content: Quote from: LapTop006 on August 17, 2017, 02:52:26 pmWell, if your mate is up to it, I could also use a battery box.A year or so ago, I laid out a PCB for the charger board but never finished it. I stopped when I started looking at options for the lamp holder and got sidetracked and never finished it.
Does anyone sell negative impedance converter (NIC)? - Page 1
Forum section: electronics / general

author: Moon Winx
author_rank: Regular Contributor
timestamp: August 09, 2017, 11:17:56 am
content: Preferably metrology-grade? I can't seem to find one commercially available, and I'm no electronics expert so DIY is out of the question until I learn more. I've seen various circuit diagrams and simulations but none actually realized/tested. I'm basically looking for a device to supply (ideally) all current across an unknown load for an attached voltage source. In other words, there should be no current draw from the voltage source (in reality, there will be some minimum current draw, but perhaps in the uA range for 1 V over a 50 ohm load). I've simulated a NIC and with the correct value feedback & divider resistors and it can do exactly that. Perhaps there are other designs/devices that could do that as well, but I'm ignorant on that.
SOLARTRON Type LM902-2 with Weston Cell on Ebay, Munich Germany - Page 1
Forum section: electronics / general

author: Harfner
author_rank: Contributor
timestamp: August 08, 2017, 03:06:51 am
content: Hello I noticed the following ebay listing:http://www.ebay.de/itm/263129114566The device is fascinating in several ways. It is so old it does not even have nixie tubes but uses twelve bulbs per digit instead. Of which there are only four, btw which fits to accuracy spec of 0,1%.The voltage standard is a (unsatured) weston cell, which does seem to work still despite its age.The "check cell voltage" does work. On my request, the seller measured an AA cell with plausible 1,589 Volt.The seller will not ship the device, as the weight is 22Kg, so this will be of interest only to the local people.

author: mimmus78
author_rank: Unknown
timestamp: August 08, 2017, 09:37:09 am
content: They don't seems nixie tubes ... but this mask/scrolling thingy.
Mil Spec LM199AH883 - Page 1
Forum section: electronics / general

author: Krytron
author_rank: Contributor
timestamp: July 29, 2017, 07:24:30 pm
content: I am in the process of retiring from the job and I found a data sheet for the mil spec version of the LM199AH/883. Pages 5 to the end is a certificate of conformance from Arrow Electronics for an order we placed.
Datron 4808 Opt. 70 Wideband Source - Page 1
Forum section: electronics / general

author: perdrix
author_rank: Frequent Contributor
timestamp: July 19, 2017, 05:30:23 pm
content: Looking at the schematics for the Wideband Source (the only document I have so far for it), the schematic page for installing it it says you need to replace the main ROM in the 4808 digital board and you also need to modify the keyboard (I think mine has been done).The ROMs on my digital board are labelled:400837-3.0 14 Feb 92401007-2.10 06/06/94401006/1.0 016007which I think implies overall revision 1.4/ECO 4500 and I think they do support Opt. 70, but I'm not sure as I get Error 9 when I press the WBV button (this could be a fault with my Opt. 70 unit).Does anyone know what the highest ROM levels available are? The schematic page for installing Opt. 70 refers to a revision level 1.8 but this may not be the highest.More worryingly I got an email offline which said:QuoteDoes anyone know anything about that?Oh yes, I anyone has any documentation apart from the schematics, I really want to hear from you.CheersDave

author: perdrix
author_rank: Frequent Contributor
timestamp: July 20, 2017, 05:06:36 pm
content: Well, I got it working (sort of).The 4808 threw "Error 9" when I tried to select the Wideband Source. When I checked the cables connecting the 4808 to the Option 70 box, I found that pin 9 of the 15 pin digital cable was open-circuit. This should carry the IDIGBUSON_H (+5v) signal to tell the box that the 4808 is powered on.Replacing the cable changed the story entirely and it now partly works.It will allow me to use Wideband Source and it will produce output (at about the right amplitude) at frequencies of 0.34MHz and above, below that frequency it is mute.Any ideas?ThanksDaveI

author: manganin
author_rank: Regular Contributor
timestamp: July 20, 2017, 05:39:15 pm
content: Quote from: perdrix on July 20, 2017, 05:06:36 pmBelow that works the main calibrator.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 23, 2017, 12:08:03 pm
content: An update:Poking around and looking at the schematic for Opt. 70 it was clear that the Stellex DDS IC isn't used for all output frequencies. For frequencies 30Hz to 330kHz inclusive, the signal is supplied on the I+ signal line of the Lemo connector (with the reference voltage on V+ - a sine with nasty x-over distortion). When I checked this at the 4808, there wasn't a signal on the I+ line at the Lemo.Checking on the motherboard, the signal was present and correct. It turns out that the wire to that pin of the Lemo socket on the back panel of the 4808 had never seen solder! It looked OK because it was covered by an insulating sleeve, but it must have moved sufficiently to break contact when I took the rear panel off to get at the key-lock.Anyway, all now soldered up and working well.PS to get higher frequencies out of the Opt. 70 source, you just need to press the Store/x100 button (top left corner of lower left keypad).Dave

author: TiN
author_rank: Super Contributor
timestamp: July 23, 2017, 02:05:01 pm
content: This thread is sadly worthless without photos.
Valhalla 2703 Service Manual - Page 1
Forum section: electronics / general

author: e61_phil
author_rank: Frequent Contributor
timestamp: July 27, 2017, 07:25:45 pm
content: Hi,I'm looking for the service manual of the Valhalla 2703 AC calibrator. Mine isn't as stable as it should be.I read "The nice thing about the 2703 (like a lot of older tech stuff) is that there is no secret jiu-jiu in it. All off the shelf parts and freely downloadable service manual" on the volt-nuts mailing list. But I couldn't find it online.Does anyone have a copy?Thx Philipp

author: The Soulman
author_rank: Super Contributor
timestamp: July 27, 2017, 07:32:05 pm
content: http://www.valhallascientific.com/manuals/2703_2705_Manual.pdf

author: e61_phil
author_rank: Frequent Contributor
timestamp: July 27, 2017, 07:39:55 pm
content: Thx. I was completley fixed on the term "service manual" and overlooked thatSorry guys

author: The Soulman
author_rank: Super Contributor
timestamp: July 27, 2017, 07:46:28 pm
content: No worries.
What is a  42841A Bias Current Source used for? - Page 1
Forum section: electronics / general

author: carl_lab
author_rank: Frequent Contributor
timestamp: July 27, 2017, 07:07:48 pm
content: Maybe this is a stupid question: what is a 42841A Bias Current Source used for?I had a look at the user manual, but still did not understand...OK, I found the application note and the answer:It is used fot measuring inductors for use in SMPS under realistic operation conditions (DC current biased).
MTD415 - a low cost, RS232-controllable, bipolar 1,5A TEC controller-module - Page 1
Forum section: electronics / general

author: Echo88
author_rank: Frequent Contributor
timestamp: July 22, 2017, 09:00:31 pm
content: As voltnuts we sometimes need very stable thermal conditions or want to test the TC of whatever component, so maybe the following is helpful for you guys:In my search for a reasonable cost TEC controller i came across the MTD415-module, which is at the moment for sale at Thorlabs.They are nifty little RS232-controllable +-1,5A bipolar TEC-drivers with onboard digital PID-controller.So i bought one to test it (an MTD415T for 10k NTC sensors) and was satisfied with its stated performance. I achieved about 10mK stability (like advertised) in an less than optimal thermal setup.Much better stability wont be achievable i think, because of the inherent low adc-resolution and the TEC-current resolution, but i might be wrong.In comparison to the usual small bipolar TEC-drivers/controllers (LTC1923, ADN8831, Analog Technologies TEC controllers) this solution is, in my opinion, remarkable because of the simple PID-control: no resistors/caps to change while finding the perfect PID-parameters, just change the parameters of anything via RS232. With about 24€ its about as cheap as a LTC1923/ADN8831-solution (including the necessary pcb) and way cheaper than the controller from Analog Technologies. Of course the MTD415 cant temp-stabilise an object as good as the other aforementioned analog solutions, but most of the time one doesnt need 1mK stability.Links:https://www.thorlabs.de/newgrouppage9.cfm?objectgroup_id=10626http://shop.analogtechnologies.com/TEC-Controllers_c6.htmIm not affiliated with Thorlabs and just wanted to share my findings with you, maybe someone can use this module in an interesting project.Greetings,EchoEdit: Added a photo of the interior. Datasheets for two recognized ICs:https://www.diodes.com/assets/Datasheets/AUR9718B.pdfhttps://www.silabs.com/documents/public/data-sheets/efm8bb2-datasheet.pdf

author: Andreas
author_rank: Super Contributor
timestamp: July 23, 2017, 08:16:31 am
content: Hello,Photos of your setup?Did you only measure the temperature sensor (directly at the TEC) or some components more far on the PCB?But on the other side: a 5V 1.5A TEC is shurely only intended to cool single chips.With best regardsAndreas

author: Echo88
author_rank: Frequent Contributor
timestamp: July 23, 2017, 12:28:17 pm
content: I have already disassembled the structure; basically it was just a CPU-heatsink with fan, a suitable TEC and a about 100x80x10 mm aluminium block on top of the TEC, which was covered with paper to avoid air drafts. A 10k NTC sitting, thermally coupled with thermal paste, in a bore directly in the middle of the aluminium block was measuring the temperature.
Datron 4800 series board extenders - Page 1
Forum section: electronics / general

author: perdrix
author_rank: Frequent Contributor
timestamp: July 21, 2017, 09:50:54 am
content: Does anyone own or have access to a set? If so I'd much appreciate seeing pictures and knowing how many boards in the set.I think a set may comprise four boards - two for the long boards at the front, one for the 35/50V supply and one for the HV board.CheersDave
Calibration key for Datron/Wavetek 4800 series calibrators - Page 1
Forum section: electronics / general

author: perdrix
author_rank: Frequent Contributor
timestamp: July 11, 2017, 11:14:15 am
content: Hi follks, I'm looking for a calibration key for my Datron 4808.ThanksDave

author: 0.01C
author_rank: Regular Contributor
timestamp: July 11, 2017, 03:32:46 pm
content: It is ues 80's Yale lock

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: July 11, 2017, 04:00:56 pm
content: Dave,I thought I replied to this on the volt-nuts group. I have a key that was made to fit my 4700 but the locksmith didn't do a good job. However, it works perfectly on my 4808. I can have one made and drop it in the mail for you.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 11, 2017, 04:01:54 pm
content: OK, but Yale locks came with many 100s of differs, so that only helps a bit.D.

author: quarks
author_rank: Frequent Contributor
timestamp: July 11, 2017, 05:44:34 pm
content: afaik all 4808 use the same key and all of mine do, therefore Todds key should perfectly work

author: perdrix
author_rank: Frequent Contributor
timestamp: July 11, 2017, 08:38:01 pm
content: Once I've done the current calibration batch I'll turn it off, remove the lock and take it down to the local locksmith to see if he can prove his worth!Update: Locksmith declined to make key but found a matching blank. A fine diamond file and 45 minutes later I'd made a key to fit ...Dave

author: lukier
author_rank: Unknown
timestamp: July 11, 2017, 08:42:11 pm
content: What is so special about this lock? Does it prohibit opening the case as well? Maybe this is a noob question, but everytime I have a piece of equipment with a lock switch (and missing key), like the ILX Laser Diode controller, I just buy a similar one (cutout dimension, contact type) from Farnell and replace.

author: philpem
author_rank: Frequent Contributor
timestamp: July 20, 2017, 07:13:20 pm
content: Sometimes it's nice to keep equipment "exactly as it was". I follow this path - where it's sensible to do so.Also, later owners may be expecting a standard key to fit -- and might be a bit perplexed if the switch has been replaced and the requisite key is missing.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 20, 2017, 09:00:22 pm
content: Quote from: philpem on July 20, 2017, 07:13:20 pmHi Phil, Agree 100%Cheers Dave Partridge
High voltage divider - what company is this? - Page 1
Forum section: electronics / general

author: daqq
author_rank: Super Contributor
timestamp: September 03, 2017, 12:10:36 pm
content: Hi guys,I bought a 5000:1 high voltage divider, 1GOhm to 200kOhm. The device seems very accurate as far as I can measure. It's solidly built, fancy connectors, no expense was spared.But I can't find the company that made it. It might be an internal use device, or a part of a device, I don't know.Attached is a photo of the device. Any guess as to who the logo belongs to?Thanks,David

author: daqq
author_rank: Super Contributor
timestamp: September 03, 2017, 12:12:34 pm
content: Resistor stack photo.

author: daqq
author_rank: Super Contributor
timestamp: September 03, 2017, 12:58:47 pm
content: So, the measurement:Input voltage: 20.00457VOutput voltage: The last digits jumped around a bit, but the voltage shown was within the range of 3.99995mV to 4.00023mV (quick measurement, measured on HP 3458A, NPLC 100, no particular consideration to thermocouple voltages etc., input impedance set to super high). Ideally, with a 5000:1 divider this would be 4.00011...mV. So a ratio error of less than 0.005%! Weird...

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: September 03, 2017, 01:19:41 pm
content: I would guess Measurements International but the current symbol on their latest products doesn't match.
Where to buy highly precise sense resistors? - Page 1
Forum section: electronics / general

author: jkrbasu
author_rank: Contributor
timestamp: July 18, 2017, 09:05:26 am
content: Hello again!For those of you who spend a lot of time calibrating- where do you get your high precision sense resistors? And what's the best tolerance you've seen? I've seen +/- 0.005% in some of Dave's videos, but haven't come across anything like that in the flesh! I'd like to get some in the range of 0.1 to 100 Ohms (four decades)Cheers-

author: SvanGool
author_rank: Regular Contributor
timestamp: July 18, 2017, 11:36:24 am
content: If you insist on the accuracy, you can find a used 0.005% 100 Ohm hermetically sealed (no humidity impact) 2ppm/°C resistorhereand you get a 1K resistor for free.

author: ap
author_rank: Frequent Contributor
timestamp: July 18, 2017, 11:46:39 am
content: There are several contributors to what you define as precise:-initial accuracy (sometimes parts do not even meet these, be carefull)-aging drift (aging effects from humidity, crystal structure changes...)-thermal driftSo to minimize this, I am using hermetic, low tempco resistors (VPG...), with applied power limited to 10mW, so mainly for the mA measurements, and for lower impedances (higher power), Isabellenhütte devices (1ppm/K); not cheap though. Hermetic power resistors from VPG or wirewounds may be an option. The latter have a higher aging rate. All depends on your budget and accuracy requirements (not only initial accuracy). Also, AC sensing may e.g. make wirewounds a no-go.

author: jkrbasu
author_rank: Contributor
timestamp: July 18, 2017, 06:30:23 pm
content: Thanks guys! Looks like the Vishay products are the way to go. I'll keep my eyes peeled for these on eBay

author: alm
author_rank: Super Contributor
timestamp: July 19, 2017, 04:53:55 am
content: What is the word on the performance of desoldered VPG resistors from suspect sources (i.e. eBay)?

author: SvanGool
author_rank: Regular Contributor
timestamp: July 19, 2017, 03:47:54 pm
content: I would take a lookhere, TiN tested a lot of used resistors and my personal conclusion would be that at least the TCR is not bad. I know he also uses sometimes the source I mentioned above.
SIGLENT SDG1025 FAIL - Page 1
Forum section: electronics / general

author: ekrzychoooo
author_rank: Newbie
timestamp: July 11, 2017, 01:27:40 pm
content: HelloThe SIGLENT SDG1025 generates poor performance when changing frequencies.Please watch this movie and write what you think.Are your generators other than SIGLENT eg RIGOL having the same problem?The information has already been sent to SIGLENT.Now I'm waiting for an answer.RegardsChristopher.

author: Rbastler
author_rank: Frequent Contributor
timestamp: July 11, 2017, 04:20:00 pm
content: I never had such issues on my SDG1025. If it's a thing, mine has to go anyway, because I want one with lan.I don't have acess to it, but I will look into the problem onve I have.

author: Muxr
author_rank: Super Contributor
timestamp: July 11, 2017, 05:06:29 pm
content: I haven't experienced this with my SDG1025 but I can try to reproduce it tonight. I do remember updating firmware on mine when I first bought it because it had some bugs, but I can't remember what those bugs were of the top of my head.

author: ekrzychoooo
author_rank: Newbie
timestamp: July 12, 2017, 10:12:26 am
content: Here is the next movie.Switch to text, in Englishhttps://youtu.be/ulQ1FglQGPY

author: nctnico
author_rank: Super Contributor
timestamp: July 12, 2017, 10:22:05 am
content: This is normal behaviour for many (if not all) digital function generators. If you need defined behaviour then use the burst function combined with a trigger.

author: Rbastler
author_rank: Frequent Contributor
timestamp: July 12, 2017, 10:23:17 am
content: What firmware version do you use ?

author: ekrzychoooo
author_rank: Newbie
timestamp: July 12, 2017, 10:26:15 am
content: I use 1.01.01.39R2

author: ekrzychoooo
author_rank: Newbie
timestamp: July 12, 2017, 10:28:32 am
content: Quote from: nctnico on July 12, 2017, 10:22:05 amIt is not normal. In RIGOL generators everything is OKI use class C++Code:pseudocodefor(f=Fstart; f<Fend; f += delta){set_SDG1025(f);Sleep(100ms);measurement();}I need eg 500 samples.Function measurement(); Shows nonsense.

author: xrunner
author_rank: Super Contributor
timestamp: July 12, 2017, 11:32:03 am
content: Quote from: ekrzychoooo on July 11, 2017, 01:27:40 pmNo.(Rigol DG1032Z here)

author: ekrzychoooo
author_rank: Newbie
timestamp: July 13, 2017, 10:11:55 am
content: SDG1032X :source:http://www.elektroda.pl/rtvforum/viewtopic.php?p=16584532#16584532

author: tautech
author_rank: Super Contributor
timestamp: July 13, 2017, 08:52:47 pm
content: I think you must use the Sweep function to side step the frequency change glitch.
How to maintain a bank of standard cells - Page 1
Forum section: electronics / general

author: zhtoor
author_rank: Frequent Contributor
timestamp: July 12, 2017, 07:20:10 pm
content: Hello everybody,what would be the proper way to maintain a set of saturated standard cells ?1. oil bath design2. temperature range3. humidity issues4. automatic comparison / back-to-back nulling systemetc...regards.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 12, 2017, 07:59:37 pm
content: Really broad question. IMHO, the best way to maintain them is not to disturb them. Temperature control can be air or oil- double air ovens have been used, like Julie Research did with theirs. It should be battery backed with a substantial capacity battery because recovery time is long. Most degradation probably comes from frequent over enthusiastic comparisons. Depending on what you need to do, comparisons once a month or even twice a year might be sufficient.

author: edpalmer42
author_rank: Super Contributor
timestamp: July 12, 2017, 08:00:11 pm
content: Maybe start with this:NBS Monograph 84Standard Cells: Their Construction, Maintenance, and Characteristicshttps://archive.org/details/standardcellsthe84hame_0AFAIK, most of the 'ordinary' commercial Standard Cells (Eppley, Guildline, etc.) use air baths rather than oil.Ed

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: July 12, 2017, 08:28:07 pm
content: Question #4 start with this...http://www.dataproof.com/NBS430.PDFYou will need a meter that can measure down in the nanovolt ranges. You would also need a switching system similar to the Data Proof scanners. It can be built by using some low thermal emf relays.The NBS430 doc includes examples and they were handy when I started writing my software. Making it automated is nice but could end up being costly unless you plan on adding several cells.

author: zhtoor
author_rank: Frequent Contributor
timestamp: July 12, 2017, 11:57:50 pm
content: Quote from: ManateeMafia on July 12, 2017, 08:28:07 pmthank you, that is what i was looking for.I plan to have 9 cells in the system (maybe more if i can acquire more).regards.

author: zhtoor
author_rank: Frequent Contributor
timestamp: July 13, 2017, 12:03:25 am
content: Quote from: Conrad Hoffman on July 12, 2017, 07:59:37 pmthanks sir,i have a 24VDC / 20AH NiCd battery with an associated charger for backup purposes.sometimes we have electricity outages of 5+ hours.regards.
Equipment quiz - Page 1
Forum section: electronics / general

author: TiN
author_rank: Super Contributor
timestamp: July 13, 2017, 11:15:00 pm
content: Let's see how well our fellow nuts know the gear.What did paybay got delivered this time?

author: CalMachine
author_rank: Frequent Contributor
timestamp: July 13, 2017, 11:19:11 pm
content: It's a very sexy unit! That's what it isI don't want to spoil the fun already

author: Vgkid
author_rank: Super Contributor
timestamp: July 13, 2017, 11:35:16 pm
content: Those are esi resistors (the flat mica, and the round trim resistor), those are also the switches they use. The 2 pots are throwing me off, but I also see a large potentiometer. I'm thinking rs925.

author: TiN
author_rank: Super Contributor
timestamp: July 13, 2017, 11:38:31 pm
content: Warm, very warm

author: 0.01C
author_rank: Regular Contributor
timestamp: July 14, 2017, 12:38:18 am
content: ESI 240 Kelvin Ratio BridgeGuess what this is

author: TiN
author_rank: Super Contributor
timestamp: July 14, 2017, 01:01:39 am
content: Was too easy.Now the interesting part, as I have no intention to pay gazillion of $$ for shipping whole 242, so alternative gear will be used.Source : HP3245A.Detector: EM A10 + K2002 or Fluke 845ABStandard resistor: Fluke SL935 or G9330

author: 0.01C
author_rank: Regular Contributor
timestamp: July 14, 2017, 01:43:56 am
content: Very nice, eagerly looking forward to your review
Valhalla 2724A resistance standard manual - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: July 07, 2017, 05:28:07 pm
content: Hello,Iam looking for the schematic diagram of the relay board located underneath the main PCB. I found nothing in the various manuals available on the net. I point out that my instrument SN 36-2199 has no Aromat relays on RLC, D... but reed relays AD1A05 from American Relays. Nothing in the Errata, update section of the manual. Thank you.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: July 08, 2017, 02:22:23 am
content: I tore my house apart looking for the manual. Turns out I never bought it.I did the next best thing and took a few photos of my calibrator. I don't have a separate board under the main pcb. I also have the CPR option if that makes any difference.The quality isn't the greatest but I can send better photos if you like.My serial number isn't that far off but the year of manufacture is ~1983

author: lukier
author_rank: Unknown
timestamp: July 08, 2017, 07:32:40 am
content: Wow, interesting device. I always assumed it would be something like Fluke 5450A (i.e. a bunch of relays and resistors), but here on the photo I've noticed a LM399, which seemed odd.So I started reading the theory of operation from the manual and it is very interesting. It is just 6 reference resistors, the rest are analog control loops to draw current and provide the correct voltage drop - I guess not dissimilar to a DC load in the CR mode (chepos implement that in the microcontroller, some Agilent loads use analog multipliers).I would never think that with such technique the specs can be so good - for 10K: 90 days 7ppm + 50 uOhm, 1.5 ppm tempco. Actually, not much worse than 5450A.Thanks for the photos.
Youtube find: software correction of machine tools - Page 1
Forum section: electronics / general

author: jeremy
author_rank: Super Contributor
timestamp: June 29, 2017, 05:25:45 am
content: Hello fellow *nuts,I have been watching this video series on youtube about software correction of machine tools. It's quite interesting, and so I thought I would share it here:I haven't watched the whole thing (yet, its about 3h total), but I'll certainly be finished by the end of today

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 29, 2017, 02:13:42 pm
content: No time to watch that, but I run manual machines. A friend has a CNC shop. I was measuring one of his parts, a long turned shaft, and was surprised to see it was within 0.0002". I asked him if the machines were really that good. He said no, you just program out any taper in software. I couldn't do that part on a manual machine without very time consuming heroics.
KVD resistor tolerance calculation procedure - Page 1
Forum section: electronics / general

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 22, 2017, 06:03:45 pm
content: Hello All,i read in Mr. Conrad Hoffman's article (i am grateful that he wrote that one!) that the tolerancesrequired for the first decade resistors is 0.0037% ie; 37ppm and in each subsequent decade thetolerance level required increases by a factor of 10.does anyone know any theoretical calculations on the subject?regards.

author: Echo88
author_rank: Frequent Contributor
timestamp: June 22, 2017, 06:35:14 pm
content: I havent read the following pdf, but i think it should contain the info you search for:https://sci-hub.io/10.1109/IRE-I.1960.5006924If you think about building a KVD: the first few stages need very good matching resistors so that they dont age significantly or have a bad TC. If you dont have a access to those resistors and think cheap resistors will suffice while getting you a shiny accurate KVD: forget it. I thought about it too long ago.

author: zhtoor
author_rank: Frequent Contributor
timestamp: June 22, 2017, 06:37:16 pm
content: Quote from: Echo88 on June 22, 2017, 06:35:14 pmi have already seen that paper, but alas not the info i desire.regards.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 22, 2017, 08:02:50 pm
content: It was a long time ago, but I'm sure I just did up a spreadsheet and applied Ohm's law. I've built KVDs using plain 1/4W metal films you get in a bag of 200, and selecting them for TC. Sure, they're not the equal of a Fluke, Julie or ESI KVD, but you can work in the 10 ppm area if your temperature is stable and you use good technique. You'd be surprised at the pitfalls of using even the best KVDs in the 1 ppm region!
Datron 4800 Series Option 70 Wideband Voltage Source - Page 1
Forum section: electronics / general

author: perdrix
author_rank: Frequent Contributor
timestamp: July 10, 2017, 05:57:05 pm
content: Does anyone any data on Option 70 for the Datron 4808, the Wideband Voltage Source?My 4808 has this bolted to the bottom but it needs to be connected to the main unit via two cables, so any information on those cables would be most welcome. Any User or Service documentation for it would also be most helpful.Thanks, Dave

author: quarks
author_rank: Frequent Contributor
timestamp: July 11, 2017, 09:38:44 am
content: the "Interface Loop Through" cables use SUB-D 15 and LEMO FGG.2B 306 connectorsPIN layout is documented in the manual (i.e. att. pic. for 4600 Connection)
Open Source leveling head for Tektronix Sg-504 plugin - Page 1
Forum section: electronics / general

author: Mosaic
author_rank: Regular Contributor
timestamp: December 10, 2016, 03:40:18 pm
content: FYI all:I have published the design for my distributed parasitic 'tuned' SG-504 leveling head. These OEM heads go for > $300 as used items.You can build this one of about 1/4 of that.What's more.. the specs exceed the OEM specs so you get better calibrations...around +/-0.1dB flatness @ 4Vpp into 50?Have a look..and like it if u can!https://hackaday.io/project/18854-a-leveling-head-for-thetektronix-sg-504-sig-gen

author: timb
author_rank: Super Contributor
timestamp: December 10, 2016, 04:54:30 pm
content: Nice! Just what I needed. Are Gerbers available for the board?

author: Mosaic
author_rank: Regular Contributor
timestamp: June 16, 2017, 03:12:27 am
content: Hmm, never noticed this reply..you can generate the gerbers from the free Eaglecad download.
Used Rb: Tips and tricks on buying those. - Page 1
Forum section: electronics / general

author: technix
author_rank: Super Contributor
timestamp: June 08, 2017, 04:49:27 pm
content: I am thinking about buying a used Rb standard for a few of my upcoming projects. My already online GPS-disciplined NTP server (based on Raspberry Pi) have an input jack to accept PPS from an external source - probably a Cs or Rb standard. And I have ideas for an STM32-based connected frequency counters and DDS func gens. Those three may need Rb for low uncertainty operations.Any tips and tricks for shopping for an used Rb?Also: with GPS and DS3231 TCXO on-board, is there any point adding Rb to my Raspberry Pi based Stratum 1 NTP server? The board have an additional microcontroller intended for trimming DS3231 externally using GPS (or Rb) as a reference input, but it is currently not programmed and unused.

author: CJay
author_rank: Super Contributor
timestamp: June 08, 2017, 05:12:40 pm
content: Unless you can persuade a seller to give you a guaranteed specification on the FE-5680 devices then you need to take pot luck to some degree, some of them have an internal Rb locked DDS which is programmable to sub Hz increments in a range of roughly 0-15MHz, some have a fixed 10MHz output that isn't programmable outside of a very small range that's intended to compensate for Rb drift, others have just a 1PPS output (FE-5680B usually)LPro and PRS10 devices seem to have a better reputation than the FE devices in terms of noise but none of the common, surplus Rb standards are particularly 'clean' compared to a good OCXO and general reccommendation is to avoid if you need a low noise signal.There's a writeup atwww.ke5fx.com/rb.htmand there is more information about the various models that crop up on eBay.If your GPS is actually a GPSDOv with a respectable OCXO or can be made into one that may be a better option for you.

author: technix
author_rank: Super Contributor
timestamp: June 08, 2017, 05:19:31 pm
content: Quote from: CJay on June 08, 2017, 05:12:40 pmHow to tell if the specific FE-5680 have an internal Rb-disciplined DDS? And how to tell if it is a PPS-only device?Quote from: CJay on June 08, 2017, 05:12:40 pmWhat do you mean "clean"?Quote from: CJay on June 08, 2017, 05:12:40 pmI don't have a GPSDO or OCXO, and my GPS receiver chipset is not a timing grade one. Is it still possible to build a GPSDO out of this? Maybe using an MCU to digitally trim the OCXO in reference to the GPS PPS signal?

author: CJay
author_rank: Super Contributor
timestamp: June 08, 2017, 06:09:02 pm
content: Quote from: technix on June 08, 2017, 05:19:31 pm