hybridfree/eevblog-posts huggingface dataset:
Measuring slew rate - Page 1
Forum section: electronics / general

author: sahko123
author_rank: Frequent Contributor
timestamp: July 31, 2020, 02:54:52 pm
content: I've made a discrete opamp and am now characterising it. I've fed it some square wave and it seems to be stable and happy. Should I measure slew rate at unity gain or open loop? Also the output waveform has a delay before the square wave starts to rise. Do I measure from the beginning of the rise or from when the input goes high?

author: TimFox
author_rank: Super Contributor
timestamp: July 31, 2020, 03:07:23 pm
content: The convention is to measure "rise time" from 10% to 90% of the full transition. If that is slew-rate limited, then that would be a good region to measure the time derivative (slew rate).Note that the slope might not be limited by the slew rate: it could be limited by the slope of the input waveform, or due to the frequency response of the unit under test. This can be checked by changing the amplitude of the waveform: a true slew-rate limited wavform will have a constant slope (and therefore a longer rise time) as the amplitude increases. Of course, at lower amplitude, the slew-rate may no longer be the limiting factor and then the rise time will be constant and the slope will reduce as the amplitude is reduced.When measuring slew rate on an audio-frequency amplifier, with gain determined by feedback, I drive the input with a sine wave and increase the frequency until I can see a ramp (constant time derivative) section in the output waveform and measure its slope.

author: magic
author_rank: Super Contributor
timestamp: July 31, 2020, 08:02:17 pm
content: https://www.eevblog.com/forum/metrology/measuring-slew-rate/

author: David Hess
author_rank: Super Contributor
timestamp: August 01, 2020, 01:20:48 am
content: Quote from: sahko123 on July 31, 2020, 02:54:52 pmThe delay is caused by limited bandwidth and slew rate is completely independent of it so measure from the 10% to 90% points while ignoring the delay.Bandwidth and associated delay are a small signal phenomenon and linear. Slew rate is a large signal phenomenon and non-linear.

author: sahko123
author_rank: Frequent Contributor
timestamp: August 01, 2020, 03:06:01 pm
content: I love how you linked to my own post. I just wasn't able to access it through phone

author: garrettm
author_rank: Frequent Contributor
timestamp: August 14, 2020, 07:40:44 am
content: Read Jim Williams' Taming of the Slew (LT Application Note 94).Slew rate is related to the rise time of the step function applied to the OPA's input. So to test a very fast slew rate, you would need a very fast rise time signal source.
ET432 LCR Meter - do you have anyone at home? - Page 1
Forum section: electronics / general

author: mrcy22
author_rank: Contributor
timestamp: August 10, 2020, 03:22:43 pm
content: It looks interesting at first glance.https://www.banggood.com/ET432-Precision-Digital-LCR-Meter-100KHz-LCR-Digital-Bridge-Inductance-Resistance-Capacitance-Tester-East-Tester-Digital-LCR-Bridge-p-1532418.html?rmmds=category&cur_warehouse=CN

author: TimFox
author_rank: Super Contributor
timestamp: August 11, 2020, 03:50:17 pm
content: The ET432 has only one more frequency (40 kHz) than the well-known DE-5000, which is slightly cheaper. The ET433 can step the frequency in 1 Hz increments. I have been very happy with my DE-5000.

author: notfaded1
author_rank: Frequent Contributor
timestamp: August 13, 2020, 05:55:13 pm
content: DE-5000 here with an extra cable input module I bought and modified with big beefy Kelvin type clips on heavy duty leads. Those little leads they come with are fine for some little caps but get into big giant stereo amp caps and they really don't make sense.Bill
Looking for synthesizer boards from FE5650 and 5680A (revB) Rubidium - Page 1
Forum section: electronics / general

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: August 07, 2020, 11:25:27 pm
content: Hi,Thought I'd see if anyone has some "dead" FE 5650A or FE 5680A(the rev B). I'm looking for a few of the synthesizer modulesfor some experiments. I don't need the rest of the unit.It's the board with the two tiny pushbuttons on it. See PIX.Willing to pay, but not too much!Cheers,Corby (In the USA)
Transformer double shielding needed? - Page 1
Forum section: electronics / general

author: udok
author_rank: Regular Contributor
timestamp: August 06, 2020, 09:00:37 pm
content: I need some help from the metrology experts here:Is a double shield really needed for a 50/60 Hz transformer power supply for precise measurement systems(like LCR and Multimeters with low current ranges)?Some older HP Power supplies like the HP6177C, Keithley 237 or Datron 1281 have a double shielded transformer.Service manuals show a transformer with a first shield over the primary winding which is connected to chassis ground and a second shieldover the secondary windings, which is connected to the floating ground.This shielding stuff is very complicated for me. And a shielded transformer is always a custom made part.When is double shielding really needed and when is single shielding sufficient?Is it possible to achieve the double shielding with simpler and more available parts?How is it done in modern meters with SMPS power supplies?Thanks,Udo

author: NWerner
author_rank: Contributor
timestamp: August 06, 2020, 10:47:15 pm
content: The book "Coaxial Electrical Circuits for Interference-Free Measurements" contains more detailed tipsregarding the construction of such transformers.Another option:As far as I remember some modern pretty high spec'ed instrument (microK thermometry bridge???)uses a transformer made by two individually shielded toroidal cores interlinked by a third winding.I can't find however the original source and its late already.- so take this with a large grain of salt.

author: udok
author_rank: Regular Contributor
timestamp: August 07, 2020, 06:07:03 am
content: Thanks for the reference. That are exactly the theoretical explanations, i was looking for.It looks like it is not easy to work around a complex shielded transformer.

author: NWerner
author_rank: Contributor
timestamp: August 07, 2020, 05:36:08 pm
content: the paper I remembered was "Design and metrological applications of a low noise, high electrical isolation measurement unit"by williams, smith, Georgakopoulos, patel and Pickering 2009.the later name triggered the association to the microK.Beginning with page 3 it deals specifically with the transformer for a isolated DC/DC converter.I highly recommend the reading.

author: dietert1
author_rank: Super Contributor
timestamp: August 07, 2020, 08:19:11 pm
content: You could simulate your two transformer filter by combining two equal commercial transformers of low secondary voltage, like 6 V. First one steps down from mains voltage, the second one back up to mains voltage.Regards, Dieter
Ballantine 1396A Thermal Converters - Page 1
Forum section: electronics / general

author: w6te
author_rank: Newbie
timestamp: August 05, 2020, 08:45:42 pm
content: I have a set of three Ballantine 1396A Thermal Converters and looking for any application notes, etc. I've searched the internet, KO4bb, etc, etc. Ballantine Labs has some info but not on these specific TC's. Any help would be appreciated. I also have a set of five TC's made by a company called Solitron/Microwave that I am not coming up with anything. Again, any help would be appreciated.

author: martinr33
author_rank: Frequent Contributor
timestamp: August 06, 2020, 02:20:53 am
content: I managed to turn up a datasheet on the Ballantines:https://static1.squarespace.com/static/560bfd14e4b01fdcd8c45b5f/t/58b5e05fd2b857a4ad934fda/1488314463774/1396A.pdfSolitron looks a bit trickier. That division was likely in Tappan, NY which might give you some threads to pull.I did find one random reference:Solitron Microwave 7842-3 Thermal Converter (like an HP 11051A) tested good

author: w6te
author_rank: Newbie
timestamp: August 06, 2020, 05:04:43 pm
content: Thanks for the leads. I'll follow up.
34420A discontinued in December 2020 - Page 1
Forum section: electronics / general

author: martinr33
author_rank: Frequent Contributor
timestamp: March 10, 2020, 08:03:59 pm
content: https://www.keysight.com/en/pdx-2912898-pn-34420A/micro-ohm-meter-7-digit?nid=-31940.1242733&cc=US&lc=eng"The last day to place order for 34420A is November 30, 2020"So there must be something new coming. The 34420A is at least 26 years old. It will be interesting to see how the design changes.

author: Grandchuck
author_rank: Super Contributor
timestamp: March 10, 2020, 08:19:39 pm
content: A non RoHS compliant product. So, that will be changed and a new display and ...Will be interesting.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 10, 2020, 09:15:53 pm
content: Chances are we may see more change here than with the 3458. Except for the input amplifier this meter is not that special, and there are points that can be done better. Different from the 3458 testing a new design is not so difficult and not much black magic involved. Keysight may not not want to keep the old ADC from 34401 with it's old ASIC and µC. The old (and slow) ADC is part of the weak points.

author: Wolfgang
author_rank: Super Contributor
timestamp: March 10, 2020, 10:03:11 pm
content: Quote from: martinr33 on March 10, 2020, 08:03:59 pmRIP. My guess: new design will be black and ROHS. Not sure about the VFD, maybe keeping those became a habit.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: August 04, 2020, 12:38:36 pm
content: They changed the end date of production: now 01 December 2021There is a second model that continues to be produced:https://www.keysight.com/en/pdx-2911658-pn-EU34420A/micro-ohm-meter-7-digit-for-eu-sales-only

author: HighVoltage
author_rank: Super Contributor
timestamp: August 04, 2020, 12:43:44 pm
content: The price for used 34420A instruments has gone up over the years.A new model might not change that.My guess is that it will look like a 34470A just in black.And hopefully with the same LEMO input connector.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 04, 2020, 02:08:36 pm
content: For the 34420 it would make sense to do a complete new design (could reuse something like the ADC of the 3446x). Unlike the 3458 ADC, there is no real magic. It is just plain low level DC amplification, and the performance is not even that extraordinary, with still some room for improvement.
Tetrajunction - Page 1
Forum section: electronics / general

author: VNUTDENYER
author_rank: Contributor
timestamp: July 21, 2020, 12:34:25 pm
content: Rather than bring back a dead thread, following concerning use of THREE tetrajunctions in a VERI (improved URS) may be of interest."Mounting a tetrajunction (a 1/2-inch diam copper sphere having four terminals). A composite junction consisting of three tetrajunctions,3 A, B, and C. This is necessary because a junction may have a maximum of only four electrically symmetrical terminals ." Hess, A. E., Nano·ohm junctions for accurate ratio instruments, NBS Report No. 9158 (Jan. 1966). FROMJOURNAL OF RESEARCH of the National Bureau of Standards-C. Enginee ring and Instrumentatio n Vol. 70C, No . 3, July-September 1966https://nvlpubs.nist.gov/nistpubs/jres/70C/jresv70Cn3p169_A1b.pdfA Versatile Ratio Instrument for the High Ratio Comparison of Voltage or Resistance Alfred E. Hess* Institute for Basic Standards, National Bureau of Standards, Boulder, Colo. (April 12 . 1966)A GOOD READ

author: VNUTDENYER
author_rank: Contributor
timestamp: July 22, 2020, 12:47:20 pm
content: NIST way to make adjustable ratio divider with 11 tetrajunctions (triangle type) and 10 resistorshttps://nvlpubs.nist.gov/nistpubs/Legacy/TN/nbstechnicalnote1297.pdfEDIT: WRONG DOCUMENT, thanks dieter, STILL LOOKING FOR ITRE EDIT: PAGE 34 INhttps://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=17477In a series of measurements using such transfer standards, the NIST OHM can be extended in multiple decade values up to 10^10OHM. Neither the absolute accuracy nor long-term stability of the resistors in the transfer standards have any effect on the measurement accuracy. The concerns with the transfer standards are only with the short-term stability required to complete the measurements.REAL GOOD READ
Source for pure copper spade lug connectors that you crimp? - Page 1
Forum section: electronics / general

author: notfaded1
author_rank: Frequent Contributor
timestamp: July 17, 2020, 03:42:27 pm
content: I have a few of these that someone sent me but after looking they aren't as easy to come by as I thought they might be. I'm hoping to make better connections for measuring my LTZ1000 references and 4W resistance measurements. I recently bought some PTFE silver plated stranded copper wire to make cables with and thought some pure copper spades that can be crimped on the ends might make nice cables for some measurements. Here's the cable I just purchased and thought would make some nice 4 wire and 4 wire plus grounding DUT to Meter. I have some nice premade low EMF cables but hoped I might make some of my own.Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: July 17, 2020, 03:46:03 pm
content: the copper spade lugs I have look a little like this but I think these are actually a little bigger and made for speaker terminals. I think mine are more made for meters like we use.

author: dacman
author_rank: Frequent Contributor
timestamp: July 21, 2020, 09:46:35 pm
content: Copper Lug:https://www.edl-inc.com/Copper-Instrument-Lugs-25-Qty_p_51.htmlGold Plated Copper Lug:http://jswilley.com/Accessories.html

author: notfaded1
author_rank: Frequent Contributor
timestamp: July 22, 2020, 07:42:27 pm
content: Thanks! Exactly what I was looking for!Bill
Datron Wavetek 1271 manuals - Page 1
Forum section: electronics / general

author: volvo_nut_v70
author_rank: Regular Contributor
timestamp: July 06, 2020, 11:23:25 pm
content: I have scanned a set of 1271 manuals. It is complete and error free, BAMA and KO44b, don't know if KO44b has posted them yet. BAMA has:http://bama.edebris.com/manuals/datron/1271/
Linear Encoder Help Determining Acceptable Replacement. - Page 1
Forum section: electronics / general

author: Pork
author_rank: Contributor
timestamp: July 04, 2020, 06:13:52 pm
content: I need to replace an encoder read head with a 1250 LPI (lines per inch) scale.The scale has a leading Part number of "LB" which states the scale was originally a metric scale and that English measure measurements are rounded to two decimal places.The software is converting the inch measurements to mm.1250 LPI doesn't (exactly) equal 20µm and most scales are designated in µm theses days.I could use assistance from those with more linear encoder experience to determine an acceptable replacement.I realize a read head setup for 1250 LPI is the best choice but I've not had great luck locating one.Would a 20µm scale work or would I likely get unacceptable compound error?I've attached the datasheet.Thanks in advance

author: TimFox
author_rank: Super Contributor
timestamp: July 04, 2020, 06:22:25 pm
content: See my reply to your older post. For the LB2 series with inch calibration, the manufacturer states that the travel lengths in inches have been rounded from a metric value. The resolution values are exact (1250 l/in for the inch unit or 50 l/mm = 1270 l/in for the metric unit). The read head must match the scale.For your application, are you happier with mm or inches? Buy a new scale and head accordingly.

author: Pork
author_rank: Contributor
timestamp: July 04, 2020, 06:34:32 pm
content: Alright.Well I guess the question becomes, what would the output square wave look like if I used a 50 l/mm read head on a 1250 LPI scale?
best low noise/EMI way to transmit power to an LTZ1000 reference - Page 1
Forum section: electronics / general

author: niner_007
author_rank: Frequent Contributor
timestamp: June 25, 2020, 03:06:35 am
content: Unfortunately, being battery powered and being in the same can or cookie box, the battery together with the reference, is not an option :/What is best, low EMI, low noise option to transmit power, from shielded box A to shielded box B, where A is the power sources, and B is the reference. 100-200mA at 12-15V.Questions are, what connectors, what cables, what kind of shielding to use. My thoughts here are single, BNC or SMA. And typical BNC wires. Would a twisted shielded pair do here? Should two BNC be used, one for GND, one for power, and shield, guard? I’m trying to avoid LEMO connectors, they are expensive and I’m not sure the best thing one can come up with, even if price was of no concern. Banana are obviously out of question, due to EMI influence.

author: dietert1
author_rank: Super Contributor
timestamp: June 25, 2020, 04:18:23 am
content: For high reliability i prefer connectors to be fixed with screws. So i would recommend a D-SUB 9 for this application. I remember Andreas explain in a talk last year that the construction of those connectors was even good for low thermal EMF, since the common body reduces temperature differences. And you have enough pins to parallel some, if you want. And you can buy solid metal hats, so you can have an uninterrupted shield similar to a RF connector.When you mount a DSub into a metal enclosure, probably it can no longer be hermetic, though.Regards, Dieter

author: JohnG
author_rank: Frequent Contributor
timestamp: June 25, 2020, 01:19:40 pm
content: I'm guessing that price is, in fact, an object.If it is not, then you can go with a power over optical fiber approach. I don't know how much it costs, but I am sure it's a lot, even for 2-3 watts.Cheers,John

author: TimFox
author_rank: Super Contributor
timestamp: June 25, 2020, 02:46:59 pm
content: Hermetic d-sub connectors are available, but are very expensive ($140 in singles for this example).https://www.digikey.com/product-detail/en/cinch-connectivity-solutions/DCDH-9S4C40.5BN/116-1072-ND/6605645
Calibration, & Uncertainty Budgets for the 121GW - Page 1
Forum section: electronics / general

author: mendip_discovery
author_rank: Super Contributor
timestamp: June 27, 2020, 03:11:33 pm
content: Hello, I'm new here.Has anyone done a full calibration of the 121GW and I mean calibration as in taking measurements against a known good standard? (Not the calibration adjustment you can do in the software of the unit.)Also, has anyone done an Uncertainty Budget for one just see how good you can get them to be? I know its not really going to be the tool of the metrologist.I ask as it would be nice to see how these units compare to the specs provided and see if in the real world are they better or worse than claimed.

author: mendip_discovery
author_rank: Super Contributor
timestamp: June 27, 2020, 04:25:14 pm
content: https://1drv.ms/x/s!AoQU31lH3_fGhZYbBYfjV4rT4dbQgA?e=VmNlI5Link refers to an Excel sheet with the Specs, and an example calibration test page (not sure I will test all elements it depends on how I get on with the calibrator), never tested VA and I have never had much luck with LowZ as the calibrator doesn't like it.
Vintage weston element is it any good? - Page 1
Forum section: electronics / general

author: dzseki
author_rank: Frequent Contributor
timestamp: June 17, 2020, 05:57:33 am
content: I am not a voltnut, but at work a colleague of mine (a mechanical engineer) brought in a weston cell (Elektro Weida - Weltor, made in GDR) that was his late father's. This cell is vintage, build date ~1962. Obviously is not holding the original voltage of 1.018xxx V instead it is showing 1.014xxx V with a calibrated HP 3478A multimeter, is there any use for the cell still, or is it just a paperweight?

author: tggzzz
author_rank: Super Contributor
timestamp: June 17, 2020, 07:00:11 am
content: I have a saturated cell from '49 that is still OK. I was lucky, since they are mechanically fragile (both glass and the electrode structure) and electrically fragile (zero current must be taken in use).Unfortunately it looks like yours isn't useful any more, and is merely atoxicpaperweight due to the visible mercury and cadmium salts in the solution. But I'd wait for comments from others before taking it for safe disposal.

author: dietert1
author_rank: Super Contributor
timestamp: June 17, 2020, 07:11:31 am
content: All you want to know about Weston cells:https://www.conradhoffman.com/stdcell.htmLife span is 7 to 14 years, yours is bad.The link is an interesting read also for anybody trying to establish a lab voltage standard:QuoteRegards, Dieter

author: Harfner
author_rank: Contributor
timestamp: June 17, 2020, 07:54:23 am
content: This is most likely an unsaturated cell, which is (toxic) waste by now.

author: fant
author_rank: Contributor
timestamp: June 21, 2020, 08:51:28 pm
content: Just my few cents.This is the cell from my lab.Dated April 1964.Best regards

author: Gyro
author_rank: Super Contributor
timestamp: June 21, 2020, 09:12:50 pm
content: That one is a Muirhead saturated standard cell. Unlike the unsaturated ones, it will maintain its voltage until its capacity is exhausted, rather than over time.The voltage temperature coefficient of Saturated cells is higher though, so they need to be measured with reference to a (stable) ambient temperature. Again, you must not draw any significant current from the cell when measuring.Datasheet attached (courtesy of a fellow forum member)...P.S. From your label, it looks as if you know about them!
Keithley 2450 calibration software (homemade) - Page 1
Forum section: electronics / general

author: shodan@micron
author_rank: Contributor
timestamp: June 21, 2020, 11:59:56 pm
content: void

author: SpecialK
author_rank: Regular Contributor
timestamp: June 22, 2020, 03:08:39 am
content: meteorologist = weathermanMaybe metrologist?

author: VintageNut
author_rank: Frequent Contributor
timestamp: June 24, 2020, 12:05:08 pm
content: Have you compared specs of 34410 against 2450? My guess is that voltage is not a big deal but current will be a big deal.The 2450 is optimized for quiet low current source and measure.I would be surprised if you can calibrate the 2450 low current range with only a 34410.I think you need a very good voltage source and very good high resistance standards and possibly a picoammeter or electrometer.

author: VintageNut
author_rank: Frequent Contributor
timestamp: June 24, 2020, 11:38:41 pm
content: From my experience, the lowest current source and measure ranges drift the most and before the higher current ranges.
Resurrecting 3D Laser Scanner Need Help with Linear Encoder - Page 1
Forum section: electronics / general

author: Pork
author_rank: Contributor
timestamp: June 17, 2020, 01:09:10 am
content: So, I'm pretty much done resurrecting an old 3D laser scanner (Digibot II). I've pretty much repaired the mechanical and electrical problems but, now I'm at an impasse. One of the read heads for the X axis linear encoder is bad (the encoder uses a dual head setup for positioning the laser).It's proving impossible to find a replacement so it looks like I'm going to have to repair or replace the read head/s myself.Does anyone know of a compatible read head suitable to replace the bad one or would I be better off to depopulate the bad PCB, reverse engineer the trace, make a new PCB from scratch and repopulate it with new components?Encoder Specifications:Dynamic Research Corp.LB2B-0032-BCR10Z234LB = Factory Letters2 = 1250 LPIB = Accuracy Grade (see description)0032 = travel length in inchesB = TTL compatible line driver (without cycle interpolation)C = ZR Location is Center of TravelR = right10 = cable length (see note 3)Z234 = Special requirements (see note 1)Thanks

author: ace1903
author_rank: Regular Contributor
timestamp: June 17, 2020, 07:37:07 am
content: There is not much that can be broken on that PCB. First check for dust and contamination of light source.I have old heidenhain linear scales that are more than 30years old (from old NC machine).Just cleaned carriage with ultrasound cleaner and put oil on bearings.After cleaning check with scope outputs of LM393 then you will know if it is possible to fix this scale.

author: Pork
author_rank: Contributor
timestamp: June 17, 2020, 02:21:33 pm
content: 1. I've cleaned everything and oiled the bearings with a needle.2. I believe the glass to be good as the other read head outputs a good square wave on both A and B channels.3. The bad read head also outputs a square wave but the duty cycle is not 50/50.4. When I attempt to home the laser the bad read head runs to the end of the x+ and acts like it can't find the end of its travel.Perhaps I should start another thread and solicit some expert help in diagnosing the bad head before making another board.Thanks for taking the time to reply.

author: Pork
author_rank: Contributor
timestamp: June 17, 2020, 06:51:47 pm
content: I've started a new post dedicated just to troubleshooting the linear encoder.Thanks
Keithley 236 237 238 shuts down randomly (SOLVED) - Page 1
Forum section: electronics / general

author: Howardlong
author_rank: Super Contributor
timestamp: June 17, 2020, 03:35:35 pm
content: Here's a nice easy fix that I wasn't predicting would be this easy.As well as a 236 (which works perfectly), I've also had a Keithley 238 for a year or two, and ever since I've had it it's never remembered settings over power cycles.It wasn't a big enough deal for me to want to open it up, but in the meantime, it developed a new fault which has become increasingly common where it would just shut down after a few minutes for no apparent reason. The display goes blank, and the only way to resolve is to cycle the power.Eventually when I had some time a few months ago I checked the Lithium coin cell backup, but it had a reasonable voltage on it (3.3v). I replaced it with a new one anyway. I also looked over the caps on the power supply and all seemed good, so I just thought I'd put up with it, and leave it in the too hard / rainy day pile.Today I found time to take took another look,with the intention of digging about a bit more.First thing I looked at was the Lithium cell again, and again it had a ressoanble 3.3v on it. I then looked at the CMOS RAM chip and checked its Vdd, but there was nothing. There's a DS1210 chip as a battery backup supervisor, and neither battery input had anything on it.It turns out the clip on the coin cell holder was only making occasional connection. I cleaned it up and bent the clip it a little to encourage it, and sure enough it's been working fine for several hours now without any shutdowns, and of course it now remembers the settings after I restart it.

author: MadTux
author_rank: Frequent Contributor
timestamp: June 17, 2020, 04:38:34 pm
content: Thanks, I have a K237 with similar symptoms, failed to find the reason for it, so far.Cross-Swapped EPROMs/PALs/microcontroller, but didn't fix it.Will check, with a bit of luck, it's the same failure.
I need some manual for digital counter - Page 1
Forum section: electronics / general

author: josefma
author_rank: Newbie
timestamp: November 23, 2019, 03:20:08 pm
content: Hello, could you recomend me some web with manual for these counters?NORMA multi-counter D 3655GRUNDIG Univerzal Zähler UZ 56It would be perfect, if manual will be in English;-)Many thanks!

author: tonyalbus
author_rank: Super Contributor
timestamp: July 29, 2020, 03:10:32 pm
content: Quote from: josefma on November 23, 2019, 03:20:08 pmHi, did you ever found the servicemanual for the NORMA?i also have this counter and am looking for it.Thanks!
Tale of Two Rubidium - Page 1
Forum section: electronics / general

author: notfaded1
author_rank: Frequent Contributor
timestamp: June 13, 2020, 12:59:01 am
content: Spectratime SRO-100 disciplined with ublox M8T series as my referenceDUT is SRS PRS10 disciplined with ublox LEA-6TTIC: Pendulum CNT-90Bill
HP 3582A S/A What is Framed Button - Page 1
Forum section: electronics / general

author: Trailboss
author_rank: Contributor
timestamp: June 10, 2020, 05:47:31 pm
content: Just unboxed an old 3582A.Attempting to put it into CAL mode.The first requirement is to set all "Framed Buttons ON"I can find no reference after searching the service manual to what a "Framed Button" is.Any help for the dumbass appreciated.thnks

author: Grandchuck
author_rank: Super Contributor
timestamp: June 10, 2020, 07:15:01 pm
content: A color or shaded border around the button?

author: chuckb
author_rank: Frequent Contributor
timestamp: June 10, 2020, 08:50:26 pm
content: On page 4-2 it states "Set Both Frame Buttons...ON", so there are two of them.on page 8-7-8 Parts list The "FRAME" buttons (2ea) are Gray in color, partial PL attachedHope this helps!
REFERENCE RESISTOR - Page 1
Forum section: electronics / general

author: franklin
author_rank: Contributor
timestamp: June 10, 2020, 08:24:00 am
content: I’ve searched the forum to find something about 10 kohm reference resistor and I found several posts. For some time, I’ve been thinking of getting a reference resistor and after I got the Agilent 3458A, it became necessary to do something about it. Some of the parts I’m planning to use are:1. Vishay 10k OHM .3W .005%, 0,0ppm/°C (?), DigiKey pn 804-1059-ND‎ (‎Y407810K0000V9L‎)2. Hammond BOX 3.64"LX1.52"W, DigiKey pn HM150-ND3. Sensor RTD 100 OHM 0.3%, DigiKey pn 1759-1003-ND‎The resistor may be an overkill and I’ve found one with a little lower price; Vishay Y607110K0000T9L, 0,01%, ±0,2ppm/°C, DigiKey pn 804-1064-ND.My question is: Will the resistor have to be measured to something better than 50 ppm or is it OK to use it as it is and rely on the datasheet?

author: Dr. Frank
author_rank: Super Contributor
timestamp: June 10, 2020, 09:10:33 am
content: The question is, what you want to do with the 10kOhm reference resistor, and maybe a 10V voltage reference.Your 3458A itself, when properly calibrated, will give you some good uncertainty for U, R, I, AC/DC, although itself it is not a standard.If you want to adjust your uncalibrated 3458A (sort of un-offcial uncertainty), then you would need a stable resistor (over time and temperature), which somebody could measure / calibrate for a relatively low price.Therefore, such sort of Vishay precision resistor would be no overkill at all. I would recommend that you dig into that long thread about stability and construction of a resistor reference, where for example I have shown my VHP202Z resistor box:https://www.eevblog.com/forum/metrology/t-c-measurements-on-precision-resistors/msg464413/#msg464413.Nowadays, I would use a VHP101, 10k0000, 0.1% instead, which seems to be the ‎Y407810K0000V9L.Don't rely on the datasheets from Vishay, especially for the T.C.!You really need to have such a resistor measured by somebody, down to a few ppm perhaps, and the real T.C. you can measure on your own, using the 3458A.0.005% costs much more, but is the purpose of that, when your 3458A can be precise to < 10ppm?Also, for 10V reference, look here (it's even a much longer thread):https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg1336573/#msg1336573Frank

author: franklin
author_rank: Contributor
timestamp: June 10, 2020, 10:46:35 am
content: Thank you for the answer. I have been looking at the thread you mention but may have overlooked any resistor calibration. I’ll take a closer look.

author: Dr. Frank
author_rank: Super Contributor
timestamp: June 10, 2020, 02:00:57 pm
content: That's the build only, and a discussion, of what is reasonable-Comparisons are done by exchanges with other volt-nuts, like the MM2019, or the small, recent one:https://www.eevblog.com/forum/metrology/volt-nut-meeting-2019-in-stuttgartgermany/msg3091382/#msg3091382
Remote Heather (Ethernet) - Page 1
Forum section: electronics / general

author: bingo600
author_rank: Super Contributor
timestamp: June 05, 2020, 01:14:27 pm
content: Just a tip ....I've been using these Nport 5410 for Ether->Serial comms (RS-232 +/- 12v levels)https://www.ebay.com/itm/MOXA-Serial-Device-Server-Nport-5410-RS-232/174235845514Works excellent with lots of stuff , including Lady Heather (GPSDO sw) , just set 10ms timeout on the channel.Point heather to the ip addy:400x - where x is the channel (1..4)From my heather.cfg-ip=192.168.xxx.yyyy:4001They're industrial , and accept wide dc psu voltage ... 9..24v i think (check)Edit: The older DE-304 works too (no https , only http mgmt. if)/Bingo
Valhalla 2724 ROM - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: June 05, 2020, 05:25:08 pm
content: Hello,I am looking for a copy of the ROM and the 2 NVRAM of the Valhalla resistance standard 2724, the old black model and not the blue 2724A (ROM and NVRAM contents are different). The two NVRAM X2212 contain not only the cal data but configuration data and there is no way to a factory reset like in the 2720GS. Thank you
Fluke 5205B - Page 1
Forum section: electronics / general

author: LaserEng
author_rank: Regular Contributor
timestamp: May 29, 2020, 06:55:39 am
content: I was reading the service manual while fixing a Solartron 7150 and in the calibration section it mentions doing the calibration with a Fluke 5205B calibrator, my google fu brought up no details at all of this mystical calibrator.I know most of the fluke calibration products from the late 80's on and have heard of the 5205A power amp but never a 5205B calibrator, so was wondering if anyone on here has any details of it?

author: alm
author_rank: Super Contributor
timestamp: May 29, 2020, 12:05:14 pm
content: What manual are you looking at? The maintenance manual from KO4BB lists the Fluke 5101 calibrator + 5205 amplifier. I'm pretty sure they're also referring to the amplifier in the manual you have.

author: LaserEng
author_rank: Regular Contributor
timestamp: May 29, 2020, 01:57:52 pm
content: On page 38 of the manual at the link below it mentions Fluke 5205B. I'm just curious what the Fluke is really, I have plenty of other gear to calibrate the 7150 with but curiosity has go me searching this Fluke.http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Solartron/Solartron_7150_Maintenance_Manual.pdf

author: alm
author_rank: Super Contributor
timestamp: May 29, 2020, 05:06:45 pm
content: But a few pages later they mention the 5101 calibrator and 5205 amplifier in the same table that I already posted. I'm pretty sure this is just a typo, and it was meant to read 'Fluke 5101B'. Because then the sentence makes sense, in that the Fluke 5101B does not provide the required test uncertainty ration on most ranges. I'm not aware of Fluke reusing model numbers for different type of instruments, except maybe from different decades, like the long discontinuedFluke 750A voltage dividervs the currentFluke 750P pressure calibrator. So if anything, the Fluke 5205B would be a slightly updated version of the Fluke 5205A.

author: LaserEng
author_rank: Regular Contributor
timestamp: May 30, 2020, 07:36:38 am
content: Yes, I think you are right, I stopped reading at the paragraph that mentioned 5205B as I got intrigued at what the hell that was as I pretty much know every fluke calibrator. I should have read further onInstead of diving down the rabbit hole that I did.
Improving the low end ACV of the HP3457A - Page 1
Forum section: electronics / general

author: Tryer
author_rank: Contributor
timestamp: May 23, 2020, 08:49:17 am
content: I bought my device end of last year from eBay.It is built in 89. with a main controller 03457-66511 Rev.B and an AC board labeled 09-8950.Playing around with it, i noticed that in ACV, on all ranges,whith shorted input, i had a quite "big" reading.In the ACV 300V range this was something like 0.4VThe AC measurement in the 3457 is done by an RMS to DC converter the AD637 (U305).I measured a small DC voltage at pin 13, which was present even with shorted inputs.If only AC were needed, a coupling capacitor would solve the problem.But in 3457 there is also the AC+DC mode and this is propably the reason for the DC coupling.Searching around i found that i could bring it to zero by changing slightly the input offsetof the U308 opamp.This improved the situation significantly.This opamp is part of a DC canceling feedback for the input of the AD637.For ACV it is configured as an integrator with a time constantτ1=200k*C323 or τ2=200k*(C320 C323) depending on Q300 (HFAC).(This is propably controlled by ACBAND command).The "fast" AC mode gives 4.4ms, the slow AC mode 48.4ms.Again this is not an "AC-path".To make it short, the next thing was to put a socket in U308 and replace it.I had a chop OPAMP in my drawer the MAX420. The two 100nf caps, which are necessary for the MAX,were placed and wired on the tot of it.This improved the situation significantly.An absolute 0 reading, even with 0V DC, cannot be reached, as the input is relative wide (>1MHz) andall the noise will be treated as an AC signal.With shorted inputs, i have the following readings after the change:ACV 30mV : ~6uVACV 300mV: ~25uVACV 3V : ~0.3mVACV 30V : ~2.4mVACV300V : ~25mVAll above values were ~15 times higher.The high-end values and AC response are not influenced by that change.This "tweak" makes only sense, if the low end readings are unacceptable high
ZYT GPSDO - Simple question - Page 1
Forum section: electronics / general

author: rubidium
author_rank: Regular Contributor
timestamp: May 13, 2020, 04:56:15 pm
content: I just received one of the ZYT GPSDO variants - the one with Symmetricom guts. I have a very simple question pose to those who own one of these, for which I can't get any insight from the rather sparse documentation. My issue is that - out of the box - I'm NOT getting a 10MHz sinusoidal output on the port marked as such. Rather, I'm getting ~200mV RMS noise. There are 2 other CMOS-level square-wave outputs at which I am getting the proper signal assigned to them. I am also getting a 1pps signal from that port. My question is: Must I have GPS lock in order to get a proper signal at the sine wave port? I was under the impression that all of the outputs traced to the OCXO, which should be running continuously - albeit not disciplined to the last decimal place if there's no GPS lock. I'm simply doing a first-order exam of this unit and trying to resolve any functional issues to know if I need to complain about a problem to the seller.Thanks,Jim

author: WPXS472
author_rank: Regular Contributor
timestamp: May 21, 2020, 04:27:46 pm
content: I am not familiar with the "ZYT" GPSDO, however I am somewhat familiar with a small GPSDO with Symmetricomm guts. If your unit is the same, it will have a small switch labelled "MACT". Press this switch to get 10 MHz with the GPS not locked. These units were intended to not output 10 MHz without the GPS being locked.

author: rubidium
author_rank: Regular Contributor
timestamp: May 22, 2020, 11:08:36 pm
content: Yes indeed! The MACT push button delivers the 10MHz sine without GPS lock. Thanks. I just wanted to test the box, but didn't have a 5V antenna on hand and needed to order one.Jim
General Radio 1433-H Decade Box Repair - Page 1
Forum section: electronics / general

author: zekeymonkey
author_rank: Newbie
timestamp: May 19, 2020, 01:17:44 am
content: I picked up a General Radio 1433-H decade box as part of a lot I purchased as auction. Unfortunately, some gorilla forced the 1Ω step switch to turn far enough to damage the wipers. To repair this, I picked up another switch assembly off of Ebay and plan is to just replace the wiper assembly.I was going to perform the repair tonight, but I started thinking. What type of solder should I use? Should I use lead or some type of silver solder? The connection between each decade switch appears to be made with silver or silver plated copper wire.While I'm asking questions, what type of lubricant should be used on the switch contacts?Thanks

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: May 19, 2020, 02:07:50 pm
content: Those are so heavy I can't imagine anybody damaging one. Plain 63/37 rosin solder will be fine. They were wired with heavy tinned buss wire and you shouldn't have to replace any wire. If I needed to replace wire I'd probably strip some bare copper out of a length of suitable gage romex and just tin it by hand. If that were too heavy, I'd buy the right wire, but I'm big on maintaining originality.

author: dacman
author_rank: Frequent Contributor
timestamp: May 19, 2020, 09:35:37 pm
content: The wipers can be bent back down. (Remove the screws that hold the tensioner for the detent bearing. Remove the setscrews that hold the shaft. The mechanism can then be picked up far enough to bend the arms back down.) I use a lubricant called LPS-1.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 19, 2020, 10:15:46 pm
content: Hi,Let me share a few photographs. This were taken from my 1433-HThere are two set screws 90oapart.Watch you don't loose the indent ball bearing.Here are a couple pictures of a spare 10kdecade Genrad 510-FThese were sold for use as a component. The letter was used to indicate the decade.Regards,Jay_Diddy_B

author: zekeymonkey
author_rank: Newbie
timestamp: May 22, 2020, 12:45:28 am
content: Thanks to everyone. I went ahead and swapped out the wiper assembly and the 1Ω steps work perfectly.I hadn't noticed, but one of the resistors on the 1 MΩ step decade has been removed and bypassed at some point. I guess I'll keep my eyes open for a high precision 1 MΩ resistor to replace the missing one.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: May 22, 2020, 02:45:49 pm
content: That's very odd. You'd have to apply a lot of voltage to burn one out, something common with the lower values. I'd just select something like an RN70D part.
Making a start on automating DM3058 Calibration/Alignment - Page 1
Forum section: electronics / general

author: bveina
author_rank: Newbie
timestamp: May 20, 2020, 01:22:47 am
content: At one point in the past i had looked into ways to align the Rigol DM3058E multimeters. there was a hand calibration procedure that needed to be repeated by hand for each range retyping the password in each time. (typing the password 30ish times per unit was a turn off)There was no published alignment procedure. I have been working on the problem on and off for a while and finally have something worthwhile to share.As of tonight i can modify the calibration constants using nothing but scpi command and have them write them out to flash. Its been a fun challenge but its far from over. if people are interested my github has lots of documentation and some python scripts to interface with a calibrator/power supply and the DMM.https://github.com/bveina/DM3058E-Calibrationmetrology trigger warning: it may look like Im using a DP832 to calibrate my DMM, but im only using it to cause noticeable changes to the calibration constants. (cant take the real calibrator home for lockdown (also it wont fit on my home desk.))Im hoping this can help some people similar to the DP832 calibration procedure that was published by TooOldForThis a while back. comments and questions are welcome.
DC calibrators noise 1. Fluke 8520A v HP 3458A - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: May 19, 2020, 11:20:02 am
content: I intend to mesure the noise of various DC calibrators. Generaly they are specified in two bands : 0,1 to 10 Hz and 10Hz to 10 Khz but almost all (except Fluke --before the 5730--) manufacturers don't explain anything about specs verification. Other manufacturers (Datron, Wavetek...) speak about average in 1 or 10 line periods () and exotic bands (DC 2Hz null detector...) without, too, verification process. I would like to make a systematic approach of the problem and I have several questions.1. First question for the lowest band (0,1 to 10 Hz): Fluke 5700 manual as 5440B uses a 8520A to mesure the standard deviation of several mesurements but I don't understand the relation between the sample rate (they use max, 20 per second) and filter set at 1000 ms. User manual is very unclear speaking about analog and digital filtering enabling optimum reject of the mains period.How can I get the same mesurement with a 3458A ? Standard deviation, no problem, reading rate per second, no problem but filter and NPLC ? And, the last but not the least, how to make the difference between the noise of the 8520A/3458A and the noise of the calibrator ? All DC serious mesurements of the 3458A use 100 NPLC...

author: Kleinstein
author_rank: Super Contributor
timestamp: May 19, 2020, 03:09:42 pm
content: The Fluke 8520 can use an analog filter at the input, while the 3458 does not have this option. So it can not easily recreate the same noise bandwidth as the 8520 with the filter enabled. If at all this would be in the non-auto zero mode, but this would add extra 1/f noise so it may not be adequate. The additional noise due to the lacking filter would be in the 25 Hz , 2.5 Hz or similar range depending on the PLC setting used.

author: guenthert
author_rank: Frequent Contributor
timestamp: May 19, 2020, 03:48:36 pm
content: I have doubts that those instruments are the best choice to measure noise. The HP3458A is comparatively fast, but the Fluke 8520A will take its sweet time (~20s!) to measure at best resolution. Worse, they'll integrate over a long time (100 or more PLC, as you already stated), so some 'equivalent time sampling' technique won't work. You could add some fast S&H circuity, but how much noise will that introduce?What's wrong with the traditional approach (DC blocking high quality capacitor in series with a LNA and a modest, but quick sampling DMM or oscilloscope)?
DC calibrators noise 2. Datron 4XXXX specifications - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: May 19, 2020, 11:53:21 am
content: Chapter 2 : how do you verify such Datron noise specs (example of the 4708). For the DC 2Hz I guess with a null detector and a strip chart recorder with band pass of 2 Hz ?
Agilent DMM utility shows 2 extra digits on 34401A ??? - Page 1
Forum section: electronics / general

author: kawal
author_rank: Frequent Contributor
timestamp: May 16, 2020, 04:17:54 pm
content: Setting up my meter to do logging using Agilent DMM Utility i noticed extra 2 digits being displayed. How is it possible if the meter is 6 1/2 digit and maybe there is an internal extra 1 digit but 2 extra digits? Meter running with shorted input 10 NPLC, every 1 s 100mV range, connection is GPIB.Is this real or some calculated number? Not sure it matters but I am sure people have had experience with this.

author: kawal
author_rank: Frequent Contributor
timestamp: May 16, 2020, 04:57:19 pm
content: Checked using 9V battery to make sure its not a range thing. Seems the same happens on 10V range.But looking a the data deeper it seems the the extra digits are at predefined levels like 04,16,28,41,53.66,78,91.... so not really extra digits....I guess I answered my own question.

author: dl1640
author_rank: Regular Contributor
timestamp: May 19, 2020, 10:41:06 am
content: You can have an extra digit if readings are stored in internal memory.
Cheap AD584 Reference PCB Battery Holder - Page 1
Forum section: electronics / general

author: juchong
author_rank: Newbie
timestamp: May 15, 2020, 05:10:02 pm
content: Hi folks,First post! Woohoo!I threw together a little battery adapter for use on my cheap AD584LH reference PCB that requires a strange, expensive 15V battery. I'm stacking seven AG13 batteries to make ~21V, perfectly suitable for this application. I'm not sure what battery life will be like, but for short-term use, this should work just fine.I hope a few folks find this useful!https://www.thingiverse.com/thing:4365796

author: sab
author_rank: Contributor
timestamp: May 15, 2020, 07:08:30 pm
content: Clever Idea!

author: juchong
author_rank: Newbie
timestamp: May 15, 2020, 07:25:02 pm
content: Thanks! The project has been on the to-do list for a while, but with the shutdown I finally found some time to knock it out.
Fluke 5700A first generation software revision - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: May 12, 2020, 03:23:45 pm
content: Hello,My 5700A first generation (no series II) has its firmware on U15, 16, 17 and 18 stamped revision H. Is there a more recent one ? Thank you.

author: picburner
author_rank: Frequent Contributor
timestamp: May 12, 2020, 06:36:13 pm
content: TiN has firmware version J on its website (I think it's a 5700A first generation), look here:https://xdevs.com/fix/f5700a/#gen1_gen2The files are at the bottom of the page.