hybridfree/eevblog-posts huggingface dataset:
Protek 506/608 how to calibrate ? - Page 1
Forum section: electronics / general

author: AlexResch
author_rank: Regular Contributor
timestamp: August 29, 2018, 07:27:36 pm
content: I have Protek 506 and 608 both bought 2nd hand. They're working but need calibrating. Anybody can describe how that is done ? I have access to voltage standards.

author: retiredcaps
author_rank: Super Contributor
timestamp: August 29, 2018, 07:50:34 pm
content: You might be able to deduce the trimmers fromhttps://www.eevblog.com/forum/suggestions/protek-506-review/by reading the MAX134 IC datasheet?

author: thm_w
author_rank: Super Contributor
timestamp: August 29, 2018, 09:45:35 pm
content: On the 608 there is a "CAL" switch in the top right, you switch that and then use the buttons on the keypad to go through the range and apply appropriate voltage/current. You can only apply cal or skip to the next range, there is no back button. I probably documented it here already.Don't touch the pots for now.

author: BradC
author_rank: Super Contributor
timestamp: August 29, 2018, 11:46:43 pm
content: Quote from: AlexResch on August 29, 2018, 07:27:36 pmThe 506 has the cal procedure in the back of the manual. Oddly enough my 20mumble year old 506 was still spot on everywhere bar temperature, and that only required a tiny tweak.The 506 manual is available on line as a pdf (as is the schematic) although I don't recall where I found them as it has been a few years.

author: AlexResch
author_rank: Regular Contributor
timestamp: August 30, 2018, 01:12:08 pm
content: Brad, would it be possible to upload the manual somewhere ? I found the schematics but I could not find the manual.

author: BradC
author_rank: Super Contributor
timestamp: August 30, 2018, 01:14:11 pm
content: This is probably as good a place as any.

author: AlexResch
author_rank: Regular Contributor
timestamp: August 30, 2018, 01:17:29 pm
content: Thank you !!!! I found the manual for the 608 and it also has the calibration procedure.

author: IanB
author_rank: Super Contributor
timestamp: August 30, 2018, 03:30:48 pm
content: Just a nudge, in case anyone knows the answer:I am very interested in the calibration/adjustment procedure for the Protek 6500 DMM. I cannot find information about it anywhere.
Looking for a RF connector poster - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: August 31, 2018, 12:48:35 pm
content: I have seen this somewhere but now I cannot find it.There is a poster that has just about ALL of RF connectors pictured and named. It may even had a frequency range with each. It included giant broadcast type to precision type, to miniatures and sub-miniatures. If anyone knows where I can get one, please point me to it.Thank you.

author: Berni
author_rank: Super Contributor
timestamp: August 31, 2018, 01:02:13 pm
content: Actually such a poster sounds neat. Id probably want one too.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: August 31, 2018, 01:05:54 pm
content: +1

author: tkamiya
author_rank: Super Contributor
timestamp: September 01, 2018, 05:43:09 pm
content: Still not finding any. I would have thought something like that will be both good looking at practical.I kind of recall now, it was on this board someone posted either an image or a link.

author: Cerebus
author_rank: Super Contributor
timestamp: September 01, 2018, 10:52:35 pm
content: From Pasternack possibly? They certainly have one or two useful booklet size guides to the various types of connector.
Gamma spectrometry - Page 1
Forum section: electronics / general

author: dbvanhorn
author_rank: Newbie
timestamp: August 29, 2018, 06:20:36 pm
content: I hadn't seen any mention on here yet, but gamma ray spectrometry is getting affordable.http://maximus.energy/index.php/product/gamma-lite-gamma-spectroscopy-system/I have been working with one of these for about the last month.The software is a bit rough, but they physicist who produces these is actively improving it. It's very serviceable now, though some parts are not as easy to use as they could be.The NaL(Ti) probe that comes with it works well, I've been able to easily see the X-Rays from a Tritium light.You'll want a Cs-137 cal disk. I got mine through United Nuclear. That gives you 33keV and 661keV peaks.Another good cal source, and much less expensive, is Lu-176. I found some on Ebay for about $7 each in scintillator crystals. That gives you peaks at about 200 and 300keV (I don't remember exactly)

author: vindoline
author_rank: Unknown
timestamp: August 30, 2018, 12:39:18 pm
content: Looks like a nice system - and the price seems reasonable for a complete turnkey solution. If you're willing to do some DIY, you can get into the hobby for much less. For example, there is the free Theremino software with complete plans for building an HV power supply with preamp and pulse shaping at:https://www.theremino.com/en/blog/gamma-spectrometry

author: Kleinstein
author_rank: Super Contributor
timestamp: August 30, 2018, 03:03:08 pm
content: The price looks very good. The two expensive parts are the PMT and the scintillator crystal. I had expected a higher price for the detector alone.Those scintillator detectors are really quite sensitive if you compare to the cheap GM-tube, some thing like a factor 100-1000 higher count rate.
zener stability at 50-60 Celsius - Page 1
Forum section: electronics / general

author: 001
author_rank: Super Contributor
timestamp: August 28, 2018, 01:37:55 pm
content: Hi!I got late 1980th voltage referenceIt consist of common use zener at owen (constant temperature about 50 Celsius) and current sourceIs it good idea to use zener at so high temperature?Is it ok to use simple zener at owen without any buffer etc? I see what in my device zener is directly connected to output plug (a sort of simple parametric regulator)Thanx!

author: Kleinstein
author_rank: Super Contributor
timestamp: August 28, 2018, 02:37:31 pm
content: The zener diode is relatively low impedance (often in the 10 Ohms range). So there is no buffer needed in most cases. The buffer can be outside at least. In the early days it might have been attractive to have the amplifier or similar also at a constant temperature, but this is not such a big issue any more with modern OPs, well better than 1 µV/K. So it is more like keeping the power consumption inside the oven low, to avoid to much self heating.40-50 C is not yet that hot: the LM399 is running in the 90-100 C range and the LTZ1000 is also usually run above 40 C, maybe 70 C.The 40-50 C is about the lowest temperature one can keep constant with just a heater if the outside can go to 30-35 C.

author: 001
author_rank: Super Contributor
timestamp: August 28, 2018, 02:45:52 pm
content: Thanx!Is it good idea to use common zener at constant temperature instead special unit without owen?

author: Kleinstein
author_rank: Super Contributor
timestamp: August 28, 2018, 03:15:42 pm
content: In the old days low noise compensated zener references like 1N829A where a common choice. By choosing the right current one can trim the linear TC, to get a low TC - at least in a small temperature range.An small extra oven could be easier and better than trying to compensate the second order effects and was also common practice.With the linear TC adjusted via the current, the oven does not need to be super stable.Non heated references can get a low TC, but usually only over a small temperature range and the compensation circuit also adds to the drift and price. So chances are a TC adjusted zener in an oven can be lower TC than a good non heated reference.Compared to the LM399, a temperature regulated 1N829 ref diode could have similar stability / drift and lower noise. However the extra oven is quite some effort and the diodes might need screening for really low noise ones.A suitable LTZ1000 circuit should be more stable and usually lower noise.

author: 001
author_rank: Super Contributor
timestamp: August 30, 2018, 07:54:24 am
content: So my unit is probably old russianthe old zener is marked as 2C190D (russian letters) so it is 0.0002% grade by datasheetIs it still good?Can I substitute it with some 1N*** zeners? What?

author: Vgkid
author_rank: Super Contributor
timestamp: August 30, 2018, 09:15:42 am
content: That is a a rather low temperature coeficcient , I would keep it. Plus the other components were matched to it. Since this is ovened , it will drift less than most meters over a temperature shift.
thandar Digital Multimeter TM 354: need information - Page 1
Forum section: electronics / general

author: Taki
author_rank: Newbie
timestamp: August 22, 2018, 07:26:14 pm
content: Hi all,Back in the early eightis I bought the digital multimeter "thandar TM 354". That was mostly because I was interested by everything that had a connection to Sinclair. It was exposed to sunlight for many months in the shop where I bought it but I never used it, so it's a kind of NOS. I put in a battery today to see if it still works and it does! It probably needs calibration, though ;-)I couldn't find any information in the internet (not even a photo), so I wrote to AIM & THURLBY THANDAR INSTRUMENTS and they send me a scan of a leaflet they still have in their archives.Can anyone give me a hint where to find more information about this DMM? I would be thankful to know when it was produced and in which numbers. With the help of Wikipedia, I'm guessing from the fact that the leaflet mentions Sinclair Electronics Ltd as the manufacturer, that it was produced somewhere between September 1979 (when the remains of Sinclair Radionics Ltd. were renamed to Sinclair Electronics Ltd) and January 1980 (when this was changed to Thandar Electronics Ltd).I added some pictures for your leisure anywayKind regards,Taki

author: Taki
author_rank: Newbie
timestamp: August 22, 2018, 07:32:07 pm
content: Addendum:The upload restrictions force me to attach the PDF as a JPG in separate message....
Would some kind soul post a sample EZGPIB program - Page 1
Forum section: electronics / general

author: rob.manderson
author_rank: Regular Contributor
timestamp: August 20, 2018, 12:41:09 am
content: that logs multiple readings from an HP 3456? Just logging to the console window will be fine.The further I get into my GPIB code the more confusing it gets. I can see the individual bytes go by on the GPIB Analyser and sometimes they appear on the USB data stream. So it's obviously something in my code but since I'm never quite sure exactly what EZGPIB is doing it makes sense to me to ask for a sample that someone else knows works correctly within that environment.How embarassing!I do .NET code for a living!

author: guido
author_rank: Regular Contributor
timestamp: August 21, 2018, 10:27:09 pm
content: Hi,I am using this with a Prologix USB adapter:Code:Program HP3456A;Const Device = 6; // GPIB addressTimeout = 5; // timeoutVar Answer:string;begin; // mainEZGPIB_BusEnableEoi; // enable EOIEZGPIB_BusSetEos(0); // Append CR+LF to instrument commands; MODE 4EZGPIB_ScreenClear;repeatEZGPIB_BusWaitForData(Device,Answer,Timeout); // Wait for dataEZGPIB_ScreenWriteLn(Answer); // Write data to screenuntil ezgpib_kbdKeyPressed;EZGPIB_ScreenWriteLn('End');end.Warning, i do not write code for a living

author: rob.manderson
author_rank: Regular Contributor
timestamp: August 21, 2018, 11:42:55 pm
content: Thanks. Now I'll have something that lets me blame my own code!

author: edpalmer42
author_rank: Super Contributor
timestamp: August 21, 2018, 11:56:07 pm
content: Were the HP3457 example files no help?Ed

author: rob.manderson
author_rank: Regular Contributor
timestamp: August 22, 2018, 01:09:15 am
content: I gave them a try but the command language to the meter itself is quite different so it was difficult to figure out what was being sent to trigger a reply. Though now you say it I wonder I didn't think to download a manual and actually (gasp) read it to see what means what to the 3457.

author: z01z
author_rank: Regular Contributor
timestamp: August 22, 2018, 05:53:05 am
content: What GPIB adapter do you have?

author: rob.manderson
author_rank: Regular Contributor
timestamp: August 22, 2018, 12:48:27 pm
content: Home developed - based on Emanuelle Girlando's code but with extensions (control of buffer chips etc). Hence the confusion. Is the problem in my extensions, or in the base code, or something else. The plan, once it's working as a basic controller, is to add spoll functionality etc.
Oscilloquartz STAR 4+ Learning Holdover - Page 1
Forum section: electronics / general

author: Ohm_My
author_rank: Contributor
timestamp: August 13, 2018, 05:30:25 pm
content: Hello All,Typically how long is the Learning Holdover and can the duration be configured?

author: texaspyro
author_rank: Super Contributor
timestamp: August 14, 2018, 04:32:55 am
content: At least 24 hours. It is not adjustable.
Keithley 182 Nanovoltmeter CAL ERROR - Page 1
Forum section: electronics / general

author: e61_phil
author_rank: Frequent Contributor
timestamp: August 11, 2018, 07:18:12 pm
content: Hi,I noticed, that my Keithley 182 has a gain error of +1% in the 3mV and 30mV range. Therefore, I tried to recalibrate the meter. According to the manual one have to calibrate the internal divider first. Unfortunately the calibration of the divider fails (which explains why only the 3mV and 30mV ranges are out).I can run a calibration of the 30mV range (haven't tried 3mV but I should also work) without further errors, but the +1% errors stays the same. I think this is due to the (broken?) internal divider respectively the wrong gain factor.Does anyone know this problem? I haven't open the unit until now.Best regardsPhilipp

author: TiN
author_rank: Super Contributor
timestamp: August 11, 2018, 08:06:37 pm
content: Stupid question : did you calibrate main ranges before attempting divider cal?

author: e61_phil
author_rank: Frequent Contributor
timestamp: August 11, 2018, 08:09:27 pm
content: Quote from: TiN on August 11, 2018, 08:06:37 pmYes. I calibrated 30V, 3V and 300mV without problems. After that I directly tried to calibrate the divider.

author: e61_phil
author_rank: Frequent Contributor
timestamp: August 11, 2018, 09:35:18 pm
content: I tried to calibrate the 30mV and 3mV ranges by estimating the right divider ratio.After calibration of 30V, 3V and 300mV I skipped the divider calibration and I calibrated the 30mV by applying the +/-3V. After that I measured 20mV in the 30mV range (30mV overranges). I noticed the results (20.20...mV) and run the calibration again. This time I applied 2.02..V and told the K182 I will apply 2.000V (2V because of the ranges from my Fluke 5440B). I used the same correction factor while I applied 202.0..mV for calibration of the 3mV range.As far as I can verify the ranges (only my Fluke 5440B DIV output) everything is fine.That means the divider is there and works, but the K182 can't determine the ratio. I also tried to calibrate the divider with 25V instead of 30V in case the 30V will overrange the 300mV range during calibration, but that also results in a CAL ERROR.
Extenders for Datron calibrators 4XXX, 47XX, 48XX - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: April 19, 2018, 02:15:48 pm
content: Back on this old topic : extenders are finished, special connectors without edges and custom end allowing soldering on an extender, 5 keys supplied with each extender. A special one is not needed for the board with the self on the mother board. Extender is flexible enough to accept a little bend. You have just to saw slots for the keys on your calibrator (position of the key varies of course with the boards and for the kind of calibrator )

author: cellularmitosis
author_rank: Unknown
timestamp: April 19, 2018, 02:25:40 pm
content: Where did you find card edge connectors without little plastic walls at the ends?

author: jfphp
author_rank: Regular Contributor
timestamp: April 19, 2018, 02:47:14 pm
content: Made specialy for me according my specifications by a manufacturer. Not cheap !

author: quarks
author_rank: Frequent Contributor
timestamp: April 19, 2018, 04:31:25 pm
content: Looks very well madeHow much was the board and the connectors and is this one board working on all 48xx slots?

author: jfphp
author_rank: Regular Contributor
timestamp: April 19, 2018, 05:07:59 pm
content: This extender is working for all the boards (picture is made with a 4808 motherboard) with an exception : the last row with one little connectorYou can use for it a common ( HP for example ; pitch 2'54) extender as for the two connectors at the left of the calibrator for the power supplies boards.

author: Johnny10
author_rank: Frequent Contributor
timestamp: August 01, 2018, 06:12:04 pm
content: What did they cost?I have a 4000A needs some work.
what if a saturated standard cell gives zero volt - Page 1
Forum section: electronics / general

author: dl1640
author_rank: Regular Contributor
timestamp: July 27, 2018, 07:52:21 am
content: Hi,Today I got this saturated standard cell and disassembled it to see inside, i'm not sure it is alive, quickly measure it with dmm gives nearly zero volt.nameplate tells it was made in 1983...my question is how long this thing would last from the date of birth? 20 years?thanks.

author: Echo88
author_rank: Frequent Contributor
timestamp: July 27, 2018, 09:32:05 am
content: Since some of those old cells are still alive i would guess they are immortal if handled correctly (and if the chemicals/electrodes dont react over time).

author: dl1640
author_rank: Regular Contributor
timestamp: July 27, 2018, 10:00:13 am
content: The seller sold it as is.It must be improperly handled, especially by rude shipping (temperature over 35C outside, cell was upside down in the box...)I let the cell sit for the weekend then measure it one more time. 99.9% it is dead.通过我的 PRA-AL00 上的 Tapatalk发言

author: TiN
author_rank: Super Contributor
timestamp: July 27, 2018, 10:08:43 am
content: Perhaps electrode contact is mechanically broken, so while cell itself is still have EMF, there is no more access to itNow it's a Hazmat waste.

author: Gyro
author_rank: Super Contributor
timestamp: July 27, 2018, 11:30:17 am
content: A saturated cell should last until its capacity is used up, otherwise more or less indefinitely (unlike unsaturated ones). It could be that yours has been accidentally left connected to a load and fully discharged.The single tube construction looks similar to my Muirhead K-375C (capacity 1 Coulomb), datasheet attached.

author: dl1640
author_rank: Regular Contributor
timestamp: July 28, 2018, 05:13:04 am
content: Thanks, your attached is documented in 1967. My one is a 0.005 class, made against China national standard #JB 1824-76, i think equivalent one is IEC 60428-1973, i dont know the cell’s capacity. These are long obsolete and I don’t have access to nor do i have the user manual of the cell, just know the type is BC9, which would be a common type in china that many manufacturers made them in old days.

author: tggzzz
author_rank: Super Contributor
timestamp: July 28, 2018, 08:13:51 am
content: Quote from: dl1640 on July 27, 2018, 07:52:21 amThey are fragile, e.g. they may not survive being inverted/shocked.Having said that, all mine work and the oldest is dated 1949https://entertaininghacks.wordpress.com/2016/12/28/a-weston-standard-cell-an-introduction-to-voltnuttery/

author: dl1640
author_rank: Regular Contributor
timestamp: July 30, 2018, 04:13:50 am
content: your 1949 one is great.mine is completely dead.
Replace Fluke 8842A VFD display with TFT display - Page 1
Forum section: electronics / general

author: tomeo.gonzales
author_rank: Regular Contributor
timestamp: July 28, 2018, 09:15:03 pm
content: I want to know if are any project to replace the fading VFD display of a Fluke 8842A with something more modern like a TFT LCD or OLED display.I see something similar for Fluke 8850A:https://www.eevblog.com/forum/repair/fluke-8050a-and-others-gt-lcd-to-led-conversion-drop-in-replacement-screen/?topicseen] https://www.eevblog.com/forum/repair/fluke-8050a-and-others-gt-lcd-to-led-conversion-drop-in-replacement-screen/?topicseen
Simpson 260 series 8 calibration instructions (lots of photos, no really..LOTS) - Page 1
Forum section: electronics / general

author: kj7e
author_rank: Frequent Contributor
timestamp: April 29, 2018, 01:53:52 am
content: Picked up a nice Simpson 260 series 8, in good shape, nothing burnt or broken, but was missing the test leads and the the readings where a bit off even for an analog meter. After some playing I found the main issue was the 50uA shunt adjustment which affects all meter readings. This is adjusted by R1, I found best results when laying the meter flat on its back, properly zeroed first, then adjusted R1 for 80% scale or 40uA on the 50uA range. This resulted in overall best linearity on all ranges. Next adjusted R2 for 800uA in the 1mA range. The only other two adjustments are for 2.5v and 250v AC, R25 and R22 respectively. Both schematics and a US Army Technical Bulletin with some adjustment info attached (below the photos).Various manuals for the Simpson meters can be found here;http://www.simpson260.com/downloads/downloads.htmThis series uses the reverse banana plugs, ordered a set of Oldaker test leads off eBay, very flexible and high quality, nice leads.Since I love photos, here are a few showing the end results, the last time I had an analog meter was back in the 80s, a Micronta 22220. I'm really impressed with this Simpson after a few adjustments. I tried to remove some of the parallax with my camera angles.Who needs 7.5 digits anyway?

author: xrunner
author_rank: Super Contributor
timestamp: April 29, 2018, 02:49:06 am
content: Not every shot is perfectly aligned with the mirror but I can tell that it's extremely well calibrated!

author: HammerTone
author_rank: Newbie
timestamp: July 24, 2018, 03:42:32 pm
content: Based on your comments I ordered a set of the Oldaker leads .. they are very nice leads!
Fluke 8842a Resistance Incorrect in all ranges - Page 1
Forum section: electronics / general

author: Ultron81
author_rank: Contributor
timestamp: July 16, 2018, 05:03:25 pm
content: Recently picked up a 8842a. DCV seems to read OK, but the 2-wire ohms readings are completely out of whack.Went through troubleshooting with the service manual, and narrowed it down to the Ohms Current Source section of the schematics.- Supplies are OK, no ripple and voltages are within range.- -7.0V Precision Voltage Reference is on the mark.I then tested the first stage of the Ohms Current Source. The manual says to connect a 2k resistor between Reference Low and U402-19. I checked the voltage across R401 and it is correct (7.0V). Checking the output of the op-amp (U401-6), I only read -1.0V (should be -4.0V). So I noticed that U401 is an OP07, easy to find, but the JFET Q401 I cannot figure out the manufacturer's part from the markings. I attached a photo of the circuit and the markings on the JFET. Do you think I can use any n-channel JFET in place of it (with the proper voltage specs)? I plan on removing the JFET and testing it.Also, another question, what's the reason for some of the JFETs in the circuit (Q405-Q407) to have the drain and source shorted? I don't think I've ever seen that before.Thanks for your help!!

author: Kleinstein
author_rank: Super Contributor
timestamp: July 16, 2018, 06:46:25 pm
content: Chances are good that one can use a different JFET for Q401. This one is not extremely critical. A low current one like 1N4117/8 or BF245 should be OK. If at all gate leakage matters.The JFETs with D-S connected are used as low leakage diodes. For some reason (likely demand) it can be cheaper to find a JFET with guarantied low leakage than a corresponding diode.However I would not really expect Q401 to go bad - its not that much exposed. The gate still reads negative - so it could be still OK. There is quite some scattering it threshold voltage and that is what you see at the gate here.I would suspect the protection circuit, e.g. Q402-Q407 and RV402-404.

author: Ultron81
author_rank: Contributor
timestamp: July 16, 2018, 07:32:33 pm
content: Quote from: Kleinstein on July 16, 2018, 06:46:25 pmThanks for the help! Yes, you are right, Q401 is good. I removed it and tested it, seems OK. I didn't think it was bad but it was easy enough to check it.I bypassed the protection circuitry like it said in the manual, and the readings were still no good. For example, with the protection circuitry bypassed, I get around 12.55k reading on a 10k resistor. Without it bypassed, I get 5.4k on 10k resistor (these are in 20k range 2-wire).I think some of the analog switches are no good. I know at least one is, I've only checked U402 so far, and found that switch C (200k and 2000k) is always closed. I still have to check U403.
FLUKE 5500A VOLTAGE AMPLIFIER - Page 1
Forum section: electronics / general

author: Ehan
author_rank: Newbie
timestamp: July 16, 2018, 04:45:18 am
content: Excuse me,could anyone tell me what is CR36(FET)?And where can I find the explanation of this circuit?Thank you very much!

author: pigrew
author_rank: Frequent Contributor
timestamp: July 16, 2018, 04:56:02 am
content: It is a FET biased as a constant current source (also known as a constant-current diode). Probably it would be a depletion mode device, where the gate is tied to the source, so Idss current is let through.See the part list in the manual (if available) to see what the current is.

author: Ehan
author_rank: Newbie
timestamp: July 16, 2018, 05:20:30 am
content: Thanks.I will do some research
Cheap low effort voltage reference ~20ppm - Page 1
Forum section: electronics / general

author: gbaddeley
author_rank: Regular Contributor
timestamp: July 12, 2018, 10:21:57 am
content: Hi, I've been into electronics for a very long time, but new to EEVblog. I hope some kind soul can help with my query.I want to check the accuracy of DC voltage readings on my vintage Fluke 8375A to say 20ppm of true at a known temperature. I would also check my other DMMs and a vintage Keithley differential voltmeter.What are low cost / low effort / entry level voltage references that will give me a reasonable idea of accuracy at 20ppm, without going to a cal lab?Buy or build? 10 Volts or something else?Cheers, Glenn (Melbourne AU)

author: The Soulman
author_rank: Super Contributor
timestamp: July 12, 2018, 10:45:26 am
content: You might wan't take a look here:https://www.eevblog.com/forum/metrology/best-out-of-the-box-10v-reference/

author: Kleinstein
author_rank: Super Contributor
timestamp: July 12, 2018, 10:58:26 am
content: One of those relatively cheap 10 V reference boards from china are probably a good bet. The bad thing is that not all sources are reliable and the give values have a small chance to be fake - so one might need a 2 nd (different source) to be reasonably sure. Still 20 ppm error might be possible from the meters used to measure the quoted values.I am not aware of Ref chips with better than 20 ppm absolute accuracy. Chances are the effect of soldering them could be larger than that.

author: rhb
author_rank: Super Contributor
timestamp: July 13, 2018, 12:01:33 am
content: I bought a DMMCheck Plus from Doug Malone at voltagestandard.com. That's out of stock but he has the 30 ppm VREF10-003 in stock for $53 US. I'm quite tempted to get one myself. That's a low cost cal.Doug has an in cal 3458A he uses to check and adjust things before shipment and ages his references before shipment.
Help on calibrating a Multimeter UT55 - Page 1
Forum section: electronics / general

author: maujavier91
author_rank: Newbie
timestamp: July 11, 2018, 02:42:35 am
content: Hello, i have a Uni-T UT55 and is currently giving wrong readings i think the calibration is completely off, as it measures negative voltages in the VDC scale having the test leads in the air, this also occurs in VAC, measuring -230Vac in the air, or measuring negative frequency, no reading is correct, also measuring the resistance touching both test leads gives negative reading in some scales, is this a calibration error or could some part of the circuit be damaged, if it is a calibration error, how could i return it to normal readings. I attach the schematic i found online.

author: mjhvanvliet
author_rank: Newbie
timestamp: July 11, 2018, 12:37:54 pm
content: Have you tried to change the battery? I think the calibration is not your problem, but an empty battery or broken meter.The IC used is ICL7106:https://www.intersil.com/content/dam/Intersil/documents/icl7/icl7106-07-07s.pdf
Guildline 9154D - Page 1
Forum section: electronics / general

author: Electrole
author_rank: Contributor
timestamp: July 22, 2018, 09:51:26 pm
content: I have a Guildline Transvolt 9154D voltage reference which needs a replacement of the power supply batteries.Following this, I'd like to do preventive maintenance of the electronics, such as replacing the rather old electrolytic capacitors, and to check if there are other potential issues.Do any of you have experience with the Guildline 9154D, or do you perhaps know where to get schematics for it??Documentation for this thing seems to be virtually non-existing...

author: Magnificent Bastard
author_rank: Regular Contributor
timestamp: July 23, 2018, 12:22:31 am
content: Quote from: Electrole on July 22, 2018, 09:51:26 pmSend an email to Guildline with a picture of your unit (showing the serial number)-- they may take pity on you and send you a PDF of the manual.

author: ArthurDent
author_rank: Super Contributor
timestamp: July 23, 2018, 12:25:49 pm
content: One of the problems with the 9154C like I have is that the foam used around the large Dewar flask disintegrates from age and you may have the innards rattling around loose inside and the Dewar flask might break from bumps when moved or used as a portable standard. The foam turns to a gooey mess and is hard to remove and replace.Be very careful if you try to replace the foam because the cell leads are quite small, long, and easily damaged. Obviously you don't want to short the cells or put any load on them. If the 'D' model still has the mercury cell for the bridge circuit that should be removed and the mess it caused cleaned up.
Magnetic field measurements on disc magnets - Page 1
Forum section: electronics / general

author: Physikfan
author_rank: Regular Contributor
timestamp: June 26, 2018, 02:03:23 pm
content: The magnetic flux density was measured at the surface of permanent disc magnets by a Hall probe:Disc magnet 30mm diameter, height 15 mm, NdFeB:Results:Disc center 0.44 T1 cm distance 0.2 T2 cm distance 0.06 TEdge up to 0.5 TSide part of the disc (curved) 0.06 TDisc magnet 45 mm diameter, height 30 mm, NdFeB:Results:Disc center 0.52 T1 cm distance 0.28 T2 cm distance 0.14 Tedge up to 0.6 Tside part of the disc (curved) 0.06 T

author: FrankBuss
author_rank: Unknown
timestamp: June 26, 2018, 02:24:32 pm
content: That's strong, but show as the Hall probe please, and the measurement system.

author: Physikfan
author_rank: Regular Contributor
timestamp: June 27, 2018, 04:10:54 am
content: Here you can see the Hall probe as well as the Tesla meter:

author: FrankBuss
author_rank: Unknown
timestamp: June 27, 2018, 06:43:17 am
content: Why does the Tesla meter show kg?But this gives me an idea: would it be possible with a defined test object and something like a spring scale to calculate the magnetic field strength? Like you pull the spring scale as strong just before the test object gets lose from the magnet, then read the value. Could be even used the measure the field in some distance with spacers.

author: Physikfan
author_rank: Regular Contributor
timestamp: June 27, 2018, 07:09:18 am
content: kG means kiloGauss1 Tesla = 10**4 Gauss

author: FrankBuss
author_rank: Unknown
timestamp: June 27, 2018, 07:15:50 am
content: Right, this makes sense.It is confusing that there are so many things "g" can mean, like gram, gravity or Gauss, if written with a capital G. But I guess usually it is clear from context. And kg wouldn't make sense for acceleration, except maybe near the big black hole in the center of our galaxy.

author: VintageNut
author_rank: Frequent Contributor
timestamp: June 27, 2018, 09:53:04 am
content: Quote from: Physikfan on June 27, 2018, 04:10:54 amDoes the meter/probe combination have a specification for uncertainty?

author: Physikfan
author_rank: Regular Contributor
timestamp: June 27, 2018, 10:51:28 am
content: The uncertainty of the meter/probe combination is about +- 5%.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 01, 2018, 05:49:30 pm
content: Some time ago I also wanted to buy a Gauss meter, but it was not important enough to invest > EUR 50.Second option was of course to build my own.Problem was however that all those cheap lineair Hall sensors are too sensitive.Take for example the AO3503http://p.globalsources.com/IMAGES/PDT/SPEC/229/K1011923229.pdfIt's lineair section only goes up to 90mT which is about 2 orders of magnitude too sensitive for measuring normal magnets from close up. All the cheap sensors I could find were much too sensitive.

author: Physikfan
author_rank: Regular Contributor
timestamp: July 05, 2018, 12:53:53 pm
content: Using this meter/probe combination I have 4 measuring ranges:3 mT, 30 mT, 300mT and 3 T.
Card edge connectors for 88809F sampler boards from 3497A - Page 1
Forum section: electronics / general

author: rhb
author_rank: Super Contributor
timestamp: June 30, 2018, 07:20:51 pm
content: Does anyone know what connectors these are or a source for them? This is the 21 relay board.I want to build a pair of samplers for my 34401As. It seemed to me that folks in this group would be the most likely to know. I asked on the hp_agilent mailing list, but got no answer.

author: precaud
author_rank: Frequent Contributor
timestamp: July 02, 2018, 03:18:07 am
content: I'm pretty familiar with 3497A stuff. The 88809F is not a model number, you'll find it on hundreds of different pcbs from HP in that era. Any other identifying numbers there? Perhaps you can post a pic to show us what exactly it is?

author: rhb
author_rank: Super Contributor
timestamp: July 02, 2018, 09:16:55 pm
content: Full board marking is 88809F Rev B 03497-66509One connector is 36 x 2 at 0.125" pitch. The other is 25 x 2 at 0.156". Board is 0.068" thick

author: rhb
author_rank: Super Contributor
timestamp: July 02, 2018, 09:18:01 pm
content: full board

author: precaud
author_rank: Frequent Contributor
timestamp: July 03, 2018, 12:22:40 am
content: That board was used with the 44421A 20-Ch Relax Mux, and 44422A Thermocouple Relay Mux. There's a jumper on the board to set it for one or the other. You should be able to find the terminal blocks with edge connector for them on eBay for fairly reasonable money.

author: rhb
author_rank: Super Contributor
timestamp: July 03, 2018, 03:04:21 pm
content: Thanks. None at present, though I did find boards with terminal blocks for a bit more than I paid for these. I may just buy some with terminal blocks and use these as a source for relays. Meanwhile I now know what service data to look for to sort out driving them.

author: precaud
author_rank: Frequent Contributor
timestamp: July 03, 2018, 03:15:06 pm
content: It so happens that those two plugins continue to be in demand, more so than any of the others, they're very popular in solar energy circles. U of Texas bought my entire stock of 22A's last month, and want more of 'em. I have some of the 21A's.
How apropriate would an LM308HZ be as a reference amplifier? - Page 1
Forum section: electronics / general

author: IconicPCB
author_rank: Super Contributor
timestamp: June 28, 2018, 02:58:14 am
content: Please comment

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: June 28, 2018, 03:06:34 am
content: The LM308A was used in the 731B among others, it isn't the lowest in noise but not bad, a LT1012 would be a good upgrade.

author: IconicPCB
author_rank: Super Contributor
timestamp: June 28, 2018, 03:21:37 am
content: Thanks Edwin,Have been looking to purchase a handfull.LM308HZ NOS available in quantities of 10 pcs for a princely sum of AUD0.28EDIT: each

author: David Hess
author_rank: Super Contributor
timestamp: June 28, 2018, 03:26:25 pm
content: Besides its unusually low input bias current, the 308 was the choice for precision during the 301A/741 era before dedicated precision amplifiers became available and inexpensive. Sometimes users graded them for offset voltage drift or used them with an oven.Quote from: Edwin G. Pettis on June 28, 2018, 03:06:34 amAnd the LT1008 is a direct upgrade of the LM308. The LT1012 and LT1097 are the same parts with some pinout and function differences.The input bias current of the original LM308 (1.5nA typical) which lacks input bias current compensation is actually high enough that modern precision parts like the LT1001 and OP-07 would likely perform better due to lower noise and even better precision. Just watch out for pinout differences in compensation and nulling.

author: Gyro
author_rank: Super Contributor
timestamp: June 28, 2018, 03:38:53 pm
content: There's probably something to be said for having those 308s in the nice hermetic 'H' packages, but that might be offset by the Thermal emf of the Kovar leads.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: June 28, 2018, 06:42:05 pm
content: If you could get a couple of LM121's to go with them ...http://www.ti.com/lit/an/snoa655b/snoa655b.pdf
Fluke historical app. note "Changing to the 1990 Volt and Ohm" - Page 1
Forum section: electronics / general

author: lowimpedance
author_rank: Super Contributor
timestamp: June 28, 2018, 05:36:41 am
content: The application note I have uploaded ,(in parts, sorry, due to this forum limitations), maybe of interest to the hard core 'nuts' who may not have seen it yet!.Forgot which pile of papers I was searching through when it surfaced and couldn't find much reference on the web, (simple lazy search), so .......Just for document preservation and your casual entertainment of course .....here it is.

author: lowimpedance
author_rank: Super Contributor
timestamp: June 28, 2018, 05:37:36 am
content: last bits

author: AG7CK
author_rank: Regular Contributor
timestamp: June 28, 2018, 12:18:57 pm
content: And here is the sticker mentioned in the document on a Fluke 8505A DMM from ... eh .. 1990

author: Dr. Frank
author_rank: Super Contributor
timestamp: June 28, 2018, 01:40:39 pm
content: This procedure was contained initially in the NIST Technical Note 1263: 'Guidelines for Implementing the New Representations of the Volt and Ohm Effective January 1, 1990'.The document is about 8MB, so I can't upload it here, and it's not found by searching the NIST any more.Anyhow, maybe there will also be a similar procedure for the New Volt and Ohm 2019, as the difference between the current and future (final) representation can just be detected by the most sophisticated / maintained secondary standards.https://www.eevblog.com/forum/metrology/new-kilogram-volt-and-ohm-are-ready-for-si-2018/msg1344582/#msg1344582Frank

author: TiN
author_rank: Super Contributor
timestamp: June 28, 2018, 02:42:25 pm
content: My FTP does not have any silly size limits

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 28, 2018, 05:11:35 pm
content: Hey, some of my stuff is so old that the 1948 correction is of more interest-https://www.nist.gov/sites/default/files/documents/calibrations/87mscohm.pdf
Update of my Keithley 2001 - Page 1
Forum section: electronics / general

author: eurofox
author_rank: Unknown
timestamp: June 22, 2018, 01:14:15 pm
content: I updated successfully my 7 1/2 digit DMM to latest firmware and memory 2 extension thanks to information from TiN website.I calibrate it with 10K, 2VDC and 10VDC, yes it work because with 20K, 2VDC and 20VDC I got a calibration error!

author: TiN
author_rank: Super Contributor
timestamp: June 22, 2018, 01:36:42 pm
content: However your DCI/ACV calibration is still likely to be invalid, because those factors require full manufacturing level calibrations with lots more points.

author: eurofox
author_rank: Unknown
timestamp: June 22, 2018, 02:00:56 pm
content: Quote from: TiN on June 22, 2018, 01:36:42 pmFor AC it is not measurable with the source that I have, so it is not relevant and on DCI it is 24µa low on 100ma range.A full calibration of this instrument cost arms & legs.

author: TiN
author_rank: Super Contributor
timestamp: June 22, 2018, 02:05:03 pm
content: Maybe you know someone in your geo who has 5700A/4808 + 2Vrms 1Hz source to do the cal

author: Simon
author_rank: Unknown
timestamp: June 22, 2018, 07:18:31 pm
content: This entire thread is pointless!
How do I determine a measurement circuit accuracy specification? - Page 1
Forum section: electronics / general

author: RDXx
author_rank: Newbie
timestamp: June 20, 2018, 08:50:16 am
content: Lets say that I have built my own DMM.How do I determine the measurement accuracy for the different channels (voltage measure AC/DC, current measure with external CT's)?A theoretical calculation taking into consideration R-, OP-, ADC-errors will not take external electrical disturbance into consideration.If I should measure it in the real world I need perhaps measure at different temperature/scales and use a large(?) number of different individuals in order to get statistical data.How do the established DMM company's determine their accuracy?

author: TiN
author_rank: Super Contributor
timestamp: June 20, 2018, 11:17:17 am
content: You calculate all error contributors and factors of all components in signal path, and then you can determine total uncertainty.Main factors to start with would be input impedance, input signal dynamic range of interest, referene stability, switching leakage/charge injection, protection circuitry error contribution, ADC performance and calibration gain/offset accuracy.
Manual for Datron (Wavetek) 4600 Autocal Transconductance Amplifier - Page 1
Forum section: electronics / general

author: perdrix
author_rank: Frequent Contributor
timestamp: June 18, 2018, 05:36:24 pm
content: Can be downloaded from <https://groups.io/g/Datron-Wavetek/files>I'll be uploading the manuals for the 4808 as I get them scanned over the next week or so.All the bestDavid Partridge

author: CalMachine
author_rank: Frequent Contributor
timestamp: June 18, 2018, 06:17:25 pm
content: Nice!!! I've been looking for the 4600 service manual for awhile.Thank you so much!

author: Simon
author_rank: Unknown
timestamp: June 18, 2018, 06:55:03 pm
content: I'm locking this as you have the same topic in test equipment and if you wish to post further manual links I expect they will all do better there.
wanted Vref based on LK1000 ideally using xdev design yielding 1ppm quality - Page 1
Forum section: electronics / general

author: johartley2001
author_rank: Newbie
timestamp: June 19, 2018, 12:01:08 pm
content: hellohello I'm involved with calibration work and am looking for a standard to verify a 6.5 digit DMM, does anyone know where I can buy a ready assembled & tested Vref?it's seems like the xdev design the best option of is there a better option ie the design used in the HP3458Amany thanks please email on johartley2001@yahoo.com if you have info thanks
Tektronix current probes - Page 1
Forum section: electronics / general

author: Physikfan
author_rank: Regular Contributor
timestamp: June 05, 2018, 08:15:26 am
content: The relatively old current probe Tektronix P6042.This current probe allows currents from 1 mA/div to 1A/div (DC to 50 MHz) to be measured without disconnecting the circuit:The Tektronix current probe P6303, up to a maximum of 100 A.The maximum frequency, depending on current level, is 15 MHz:with the control module AM503B:The Tektronix current clamp CT5 for even higher currents up to 1000 A, but only AC, maximum frequency, depending on current level, is 20 MHz:Picture follows.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 08, 2018, 06:06:25 pm
content: Those images bring fond memories.One had to make sure to terminate the scope into 50 ohms. But the display would flash if you had not done so, if I remember correctly.
oven using mineral oil - Page 1
Forum section: electronics / general

author: niner_007
author_rank: Frequent Contributor
timestamp: May 29, 2018, 01:27:23 am
content: has anyone tried making an oven, by placing a PCB in a mineral oil bath and keeping it at a constant temperature? it feels intuitively that it could maintain a constant temperature better and more evenly than anything else, virtually eliminating temperature gradients, but I'm not sure about the effect of mineral oil on electrical signals, could it inject any noise? could very small currents flow thru it? and such, even if it is non conductive; P.S. to answer a part of my question, I guess it depends on its purity and contents, if it has impurities in it, that could be conductive, even if barely. It demands an experimentthe next best thing could be to submerge a sealed PCB in mineral oil, then conductivity and purity wouldn't be a problem

author: rhb
author_rank: Super Contributor
timestamp: May 29, 2018, 02:11:29 am
content: The PC overclocking crowd do this all the time. I have no idea what the long term effects are on the parts. Resistance standards are measured in an oil bath at the national labs.A conformal coating on the PCB would probably mitigate any chemical interaction problems.The way to do it would be to have a circulating pump with a heater and temperature sensors to measure incoming and outgoing temperatures with enough flow to have a short circulation time. And, of course, lots of insulation.

author: cellularmitosis
author_rank: Unknown
timestamp: May 29, 2018, 05:29:19 am
content: This should work well, especially for components which don't generate significant self-heating.Mineral oil will work, but over the course of years will turn acidic (which can start to alter the value of wire-wound resistors). Vishay uses silicone oil to fill their hermetically sealed resistors.Unfortunately, silicone oil is much more expensive than mineral oil.You can find mineral oil by the quart at your local pharmacy (sold as a laxative). If you have a "feed and general store" near you, they will carry mineral oil by the gallon (sold as a horse laxative), which is much cheaper per volume than at the drug store. If you absolutely have to, you can use baby oil, which is mineral oil with added perfume.If I recall, I think I picked up a gallon for about $20 at Callahan's:https://callahansgeneralstore.com/Silicone oil comes in a variety of viscosities. Here's a video comparing them:Super Lube 56101 is a 1 gallon container of 100cst silicone oil, which is $86 shipped on ebay:https://www.ebay.com/itm/332207161532edit: looks like mineral oil can be had for $15 per gallon:https://www.valleyvet.com/ct_detail.html?pgguid=30e078e9-7b6a-11d5-a192-00b0d0204ae5&sfb=1&itemguid=3269d80c-7b6a-11d5-a192-00b0d0204ae5&utm_content=11738&ccd=IFF003&CAWELAID=120295250000087149&CATARGETID=120295250000178974&cadevice=c&gclid=Cj0KCQjw0a7YBRDnARIsAJgsF3OStLdWFdBDtKRkJ8hBVSNjGn6TWz5t2_2n2FWW8AdL3Ey8bGXh3rMaApIvEALw_wcBedit 2: silicone oil is also called "dimethicone", which is apparently $32/gallon here:https://tkbtrading.com/products/dimethicone-350?variant=739374657
Anyone interested in working in a primary standards lab? (US citizens) - Page 1
Forum section: electronics / general

author: Moon Winx
author_rank: Regular Contributor
timestamp: July 08, 2018, 02:50:35 am
content: I'm not sure if this is appropriate for this forum, but we have an opening for an electronics engineer that is open to all US citizens (this is extremely rare). Pay from $63k - $116k (GS-11 - GS-13) depending on education/experience. PM me for more details. Analog electronics design, metrology, and programming experience desired.

author: sokoloff
author_rank: Super Contributor
timestamp: July 08, 2018, 02:52:08 am
content: Though it's not for me, my first question would be "Where is it?" (at least rough geography, if you can't divulge the company/agency).

author: Moon Winx
author_rank: Regular Contributor
timestamp: July 08, 2018, 04:56:29 am
content: Sorry, yeah, that info might be useful. It's the US Army Primary Standards Laboratory located in Huntsville, AL.EDIT: I should add, I'm not representing this organization in these posts. This is just an informal query.

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2018, 07:13:52 am
content: Feel free to duplicate post this in the jobs section