hybridfree/eevblog-posts huggingface dataset:
Transistor cutoff current observation - Page 1
Forum section: electronics / general

author: JohanH
author_rank: Frequent Contributor
timestamp: June 18, 2025, 07:33:47 am
content: Not sure if it belongs here, but might. This observation is from data sheets. In low current applications, it's important that BJT transistors that are turned off don't leak too much (depending on application). Many small signal transistors have low cutoff currents (as specified by data sheets). Now if you need transistors with slightly larger current handling capabilities including power dissipation ability, you quickly run into trouble with traditional small signal transistors that typically have TO92 packages (or some small SMD package), say, over half a watt.While scanning data sheets, I observed that some modern low saturation medium power transistors (BJT), have almost as low cutoff currents as traditional small signal transistors (ICBEOin low nA). While these are typically made for switching applications, and advertise low VCE(sat), which is not much of interest here, a side effect is that their cutoff currents also are typically low. One excellent example is theZXT1053AK. I haven't found transistors with higher power than that with similarly low cutoff currents, but maybe they are out there?I haven't tested this yet, but I'm thinking of using such a transistor in a variable current source application. With a medium power transistor, compliance voltage can be higher, while max current output can be increased a respectable amount compared to a signal transistor (SOA and temperature derating has to be observed).I also haven't looked into MosFETs, as my current interest is in linear DC, so I'm not sure how they compare to the above.Am I on the track here, or is there some deeper knowledge out there?

author: Kleinstein
author_rank: Super Contributor
timestamp: June 18, 2025, 10:53:46 am
content: Many of the BJTs are not build / tested for very low cutoff current. Testing for low current (< 1 nA) tends to need significant time and is thus not done if not really demanded. So the specs can well be just the test limits and the actual performance of the parts is usually quite a bit better. Just looking at the datasheets may not be enough. One may have to do actual measurements.

author: JohanH
author_rank: Frequent Contributor
timestamp: June 18, 2025, 11:45:04 am
content: OK, so many figures could just be on the safe side and actual performance is better. But it's quite clear that due to their physical properties, power transistors must have much higher leakage than small signal transistors. So that's why these new generation BJTs caught my eye. Of course, one could try some samples, but I don't have the test gear either. Would be best handled with a source meter like Keithley 2400 or similar. Better off to start with something that already have low numbers in specifications.
ready to use brush for 4 mm female banana - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: June 17, 2025, 12:02:11 pm
content: HelloAs vailable of the shelf brush , that possible to use bore brush for air gun in 177 cal , that available in nylon , cotton and even jag to hold cotton fabricDewey company make good quality oneRegardsOS
Gerber for PCB SOIC8 and MSOP test board evaluation  - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: June 17, 2025, 08:54:42 am
content: HelloST Electronic provide the gerber set for an evaluation PCB which looks interesting and aslo the manual to use ithttps://www.microchip.com/en-us/development-tool/soic8evRegardsOS
Fluke 8506A and GPIB - Page 1
Forum section: electronics / general

author: GianniPastorino
author_rank: Newbie
timestamp: June 12, 2025, 06:22:04 pm
content: Hello everyone!I’ve recently come into possession of a Fluke 8506A and I’m looking for information on how to configure it and use its IEEE-488 (GPIB) interface commands.I have a homemade GPIB/USB converter based on Arduino (AR488), and I’d like to connect the Fluke in order to log data to files.Does anyone have any information about this?Thanks in advance!

author: pqass
author_rank: Super Contributor
timestamp: June 12, 2025, 07:13:36 pm
content: You can begin with the manualhere(from page 53).Start by sending a few commands via serial terminal software to the AR488 and then you can graduate to using a logging toollike this one.

author: IanJ
author_rank: Unknown
timestamp: June 13, 2025, 07:17:06 pm
content: Try WinGPIB for logging data, playback data etc.https://www.eevblog.com/forum/metrology/3458a-logging-via-windows-app-revisited/
Calibration a vintage PPM (RTW 1206) - Page 1
Forum section: electronics / general

author: klausman
author_rank: Regular Contributor
timestamp: May 28, 2025, 02:31:06 pm
content: So I have a vintage PPM with those nice plasma bar graphs. It has three inputs:- 150 mV- 1.55V (+6dBm)- adjustable 150mV - 30VI'd like to use one of the fixed inputs, abut both of them areveryuneven between L/R (fed the very same signal, one is at 0dB, the other at -3dB).Now I have two problems:- there seems to be no service manual available for this. I have contacted the manufacturer but not heard back.- Do I need something beyond a decent sig-gen for the calibration, assuming I know what the different cal pots do?I have attached the one manual that is available on the web.

author: Gertjan
author_rank: Frequent Contributor
timestamp: May 28, 2025, 04:56:51 pm
content: Hi klausman,When the levels between L and R areveryuneven, I think the first thing to do is checking if there is a fault. Maybe some part has drifted to cause the unbalance.It is unusual for an RTW to drift that much. So first find and repair the underlying cause, and then re-calibrate.I found a more detailed operating & service manual on my hard drive. With theory of operation and calibration instructions. Please see attached.Regards, Gertjan.

author: klausman
author_rank: Regular Contributor
timestamp: May 28, 2025, 05:03:32 pm
content: I am not 100% sure yet the levels are uneven on the meter side or if it's a connector/cable problem. I could get the L/R channels to be near perfect balanced using the variable input, and the back-side pots look to be almost exactly the same, position-wise. While the manual you provided is for the 1206D (which has XLR etc) whereas mine is a dumb old 1026 (no suffix) with din connector, I am sure it will come in handy. I will also see if both of the fixed inputs are unbalanced --- the one I could easily test (150mV) was, but I'll get the the siggen for testing the other.

author: Gertjan
author_rank: Frequent Contributor
timestamp: May 28, 2025, 05:20:56 pm
content: Quote from: klausman on May 28, 2025, 05:03:32 pmFirst thing to check is whether the problem is in the meter or external (cabling etc.).Just reverse L and R, or hardwire the L and R input together. Yes, I know it is a DIN connector. But connecting pin 3 and 5 should not be too difficult.I compared the schematics of the 1206 and 1206D, and they differ more then I thought. But the principle of operation is of course the same. So i am confident that you will find your way around in your 1206.regards, Gertjan.
P327 Precision Decade Resistor - Page 1
Forum section: electronics / general

author: gmac34
author_rank: Regular Contributor
timestamp: May 28, 2025, 03:08:45 pm
content: A few pictures from a nice soviet decade box,It's supposed to be 0.01% class 1.5ppm TempcoMax residual resistance 0,012ohmAs far as I can see most of the ppms are still inside, even if the packaging was awful and two decades got damaged in shipping, they seem to glue back nicely...

author: JoanBS
author_rank: Contributor
timestamp: May 28, 2025, 04:03:18 pm
content: What a marvel! I recently built one using cheap chinese components, nothing like this work of art.

author: Victorman222
author_rank: Regular Contributor
timestamp: May 28, 2025, 04:47:39 pm
content: Nice score! The 1.5*10^-6 is not the TC, its the additional error when using less than full scale range, see attached formula for calculating the error in percent, where Rк is the full resistance of range and R is the dialed in resistance. The pdf manual is also attached.Some more interesting things from the manual:Thermal EMF less than 1 uV - the box uses copper switches and binding postsThe resistors are wound with 10ppm/C grade manganinThere should be an additional brush screwed to switches so you can make 4 wire connections to the resistor for calibration purposes.

author: Victorman222
author_rank: Regular Contributor
timestamp: May 28, 2025, 04:56:04 pm
content: Here is what is inside those aluminum shelled resistors if you are curious.

author: ZGoode
author_rank: Frequent Contributor
timestamp: May 28, 2025, 05:49:15 pm
content: Absolutely gorgeous piece of engineering. I was looking to build something similar since I have a few Gen-Rad boxes which have some damaged internal elements (but working switches as far as I can tell)

author: TimFox
author_rank: Super Contributor
timestamp: May 28, 2025, 07:17:20 pm
content: Do you know what the insulation layer (broken during disassembly) was made from?

author: Mickle T.
author_rank: Frequent Contributor
timestamp: May 28, 2025, 07:38:38 pm
content: P327 User Manual with OCR text layer.

author: Vgkid
author_rank: Super Contributor
timestamp: May 29, 2025, 07:24:55 am
content: Thanks for the teardown , it looks like a neat unit. Looks as if the main resistance element is incasrd in the Aluminum tube, and the trim resistor is mounted outside.
Irritated that I missed this Datron 4902/S & 4901 User's Handbook - Page 1
Forum section: electronics / general

author: tggzzz
author_rank: Super Contributor
timestamp: June 03, 2025, 12:40:18 pm
content: If anyone here bought this manual before I had the chance to, or if they know where I can get one, please let me know.Bonus points for a Datron 4903 manual.
Ad-hoc way to estimate absolute power using short RX antenna+spectrum analyzer? - Page 1
Forum section: electronics / general

author: incf
author_rank: Frequent Contributor
timestamp: May 25, 2025, 08:32:32 pm
content: I've got a short whip 915MHz antenna attached to a spectrum analyzer. Located several feet away is a SMPS module whose emissions I'd like to estimate.I'm interested in guesstimating absolute power received by the analyzer+antenna at 50kHz.A possible calibration point might by provided by an AM radio station whose absolute field strength is known at ~1MHz.The noise floor of the area is not known, but it is rural.Using the estimated absolute power received I hope to estimate the absolute level of emissions from a SMPS to within +/-10dB.I currently can see the switching emissions from the SMPS, they form a distinctive peak that is several DB above the noise floor. But I'd like to guesstimate what the actual field strength might be.Is this feasible? Is a short antenna suitably wide band for low frequency work? Does the specific distance from SMPS to antenna really matter when I am so far within the near field at 50kHz?It's nearly impossible to get outside of the near field at low frequencies, so maybe I might just be limited to looking at relative differences above the noise floor with the module on and off.

author: iMo
author_rank: Super Contributor
timestamp: May 26, 2025, 01:50:06 pm
content: Definitely not.For that exercise at 50kHz you would need a loop antenna of certain size, shape and number of turns. And a math.Quote from: incf on May 25, 2025, 08:32:32 pm

author: rf-fil
author_rank: Regular Contributor
timestamp: May 28, 2025, 01:50:01 am
content: This is normally done with a TEM cell. Even then, it's really hard to get absolute measurements. TEM cells are more suitable for relative measurements. You'd go to a test house, find out that your SMPS is generating a spur which is 10dB over the limit. Then you'd use the TEM cell back in your lab, to measure your design changes and try to get a 10dB reduction on that specific spur.

author: Andreas
author_rank: Super Contributor
timestamp: May 28, 2025, 07:20:14 am
content: Hmm,below 30 MHz normally a LISN is used to measure the conducted emissions.It is nearly impossible to get stable/reproducable measurement conditions in near field.And never with a "short antenna" where you loose too much sensitivity.with best regardsAndreas
World Metrology Day - 20th May 2025 - Page 1
Forum section: electronics / general

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: May 20, 2025, 06:50:23 pm
content: Today is world metrology day - 150th Anniversary of the signing of the Metre Conventionhttps://www.worldmetrologyday.org/https://www.bipm.org/en/bipm-anniversaryhttps://www.bipm.org/en/measurement-units/si-base-unitshttps://www.bipm.org/en/measurement-units/si-defining-constants
sensor clamp meter ut216c - Page 1
Forum section: electronics / general

author: firas
author_rank: Contributor
timestamp: March 09, 2025, 11:12:03 am
content: The current sensor in the meter gives me random readings. I opened the device and this is the picture. I don’t know what kind of sensor it is. Is it affected by magnetic induction? If the fault is from it. It is written on the electronic element (f78 au ), knowing that it is soldered on the surface. Where can I find it?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: March 10, 2025, 01:47:45 pm
content: Good Morning Firas, I believe you should start your search using the term: 'Hall Sensor'.It is covered most often in discussions about DC clamp meters.

author: firas
author_rank: Contributor
timestamp: May 15, 2025, 05:39:54 pm
content: It turns out that the sensor is working, but placing it in the right place is the solution. The right place is calibration in itself.
Differential amplifier for Drain - Source measurements - Page 1
Forum section: electronics / general

author: luky315
author_rank: Regular Contributor
timestamp: April 27, 2025, 11:37:11 am
content: I need a stable and reliable differential amp design to build into a test PCB. The purpose is to test the switching behaviour under different loads, temperatures and drive levels. The interesting parameter is the Drain - Source voltage, the amplifier should first of all be able to survive 60V (maximum test voltage because of safety etc.) at the inputs (MOSFET open) and then precisely amplifiy the Drain - Source voltage in saturation, even with <1A load. So we have only a few mV with low RDSon FETS, a selectable gain of 10 or even bigger would be great. Of course there is no need to be able to display the correct open mode voltaga, the amplifier should only survive it and recover "as quickly as possible" from the high differential voltage at its inputs.Is there even a viable solution for such a measurement?

author: zlymex
author_rank: Frequent Contributor
timestamp: April 27, 2025, 12:13:30 pm
content: One simple solution is using a current sense amp such as INA240A1-Q1.

author: EC8010
author_rank: Frequent Contributor
timestamp: April 27, 2025, 04:12:07 pm
content: How about a perfectly ordinary x100 op-amp, protected at the input by a 10k series resistor and a forward-biased HLMP3401 amber LED shunting the amplifier? 1980s technology amber LEDs pass very little forward current at low voltages (not enough to disturb your measurement) but will clamp the input at about 1.7V, which is low enough not to damage the amplifier. And they're fast. In theory, you could use a pair of back-to-back parallel amber LEDs, but (curiously) measured reverse leakage is poorer than forward at low voltages. The op-amp will introduce a little offset, but that's easily dealt with. Don't see why you shouldn't be able to make some quite accurate measurements.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 28, 2025, 12:46:08 am
content: Quote from: luky315 on April 27, 2025, 11:37:11 amSure, if you do not care about the open state, you can clamp the probes. There are low Cap diode arrays used to clamp USB lines, that are cheap and you adjust the Vcc (default 5V) down to set the clamp range.If your opamp has dual rails (or you can lift the diff pins with a 4 resistor diff amplifier + Ref scheme), you can also use feedback clamping, so the gain resistor is shunted with a diode for OFF signal swings.This can give faster recovery times & allows more gain, as the internal nodes within the OpAmp are never overdriven.
USB isolators for low noise measurements - Page 1
Forum section: electronics / general

author: ArgyllGargoyle
author_rank: Contributor
timestamp: April 22, 2025, 07:09:38 pm
content: Hi,Does anybody have a recommendation for a USB isolator to reduce conducted noise in precision measurements?I generally try to avoid USB when possible, but I do frequently use a GPIB-USB-HS+ adapter, and I also have a USB->Serial bridge that I use for interfacing to some instruments. I believe the NI adapter supports high-speed USB.I know there are some cheap isolators out there; just curious if anybody has found them useful (or otherwise). Alternatively, I could build one with something like ADUM4166 or equivalent.Thanks,Argyll

author: David Hess
author_rank: Super Contributor
timestamp: April 22, 2025, 07:48:46 pm
content: Any of them should be a huge improvement since they provide galvanic isolation. Ethernet is transformer isolated on both sides so should be even better.

author: ZGoode
author_rank: Frequent Contributor
timestamp: April 22, 2025, 08:05:42 pm
content: Assuming you are looking for an isolator for use specifically with that GPIB to USB adapter, I actually go the other way and isolate the GPIB bus rather than the USB. I use a NI 120A or pair of HP 37203A for GPIB bus isolation depending on how far I need to be able to send that signal. Both can be found fairly readily on eBay.Although if you are also looking for USB serial isolation, I've found pretty much anything using those galvanic Analog Devices ICs to perform good enough for my use cases

author: David Hess
author_rank: Super Contributor
timestamp: April 22, 2025, 08:58:33 pm
content: Also, I would use USB isolation whether noise was a concern or not; the galvanic isolation will prevent very expensive mistakes.
dc resistance measurements of inductors max inductance limitations on dmm? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: April 20, 2025, 07:31:10 pm
content: I see in a keithley spec sheet for the 2001 on their resistance spec sheet they specify that the inductor must have a value of less then 10mH if you want to measure the DC resistance.Why is this? I never saw it for another meter. I have TH resistor sized 100mH axial coils laying around, I must have measured it before on another meter and nothing strange happened.

author: bdunham7
author_rank: Super Contributor
timestamp: April 20, 2025, 07:57:07 pm
content: There was a previous discussion about the Keithley DMM6500. Apparently inductance can make the ohms source unstable, a Keithley-only "feature".https://www.eevblog.com/forum/testgear/keithley-dmm6500-strange-beahavor-measuring-transformer-resistance/25/

author: coppercone2
author_rank: Super Contributor
timestamp: April 20, 2025, 08:01:02 pm
content: If you put more resistance in series would it get rid of that problem? I.e. solder a 1k resistor in series with the inductor (IIRC the small ones are like in the hundreds of Ohms for 100mH inductor). Though I guess that would be hard to precisely subtract that error. Granted it would be infinitely easier to use another meterIt still might be useful to look at tempco of the inductor with a higher resolution meter

author: bdunham7
author_rank: Super Contributor
timestamp: April 21, 2025, 03:07:42 am
content: Quote from: coppercone2 on April 20, 2025, 08:01:02 pmIn that other thread someone tried that with a smaller resistor and significantly larger inductor and it didn't help. If the meter is not using a constant current source then I think you'll always have some error from the inductor. The Keithley 2001 has offset compensation where after a resistance reading it will interrupt the current source and take a residual voltage reading and then subtract that (with the appropriate math) from the resistance result. This would reduce the time that the current source has to stabilize, so perhaps that is why they have a low inductance limit.
Resistor divider 1/10 and 1/100 interesting design article  - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: April 19, 2025, 08:08:41 am
content: HelloAn article from an Italian lab on precision dc dividerthe PCB setup is interesting as 4 wire conversion with split PCBRegardsOS

author: NANOJOLTS
author_rank: Contributor
timestamp: April 20, 2025, 10:37:49 pm
content: Looks like they're using one of the, (ICS Electronics), GPIB to Relaybox's. Can't make out the part number on the yellow relays but they lookvaguely familiar.
IWATSU CS-3300 curve tracer calibration - Page 1
Forum section: electronics / general

author: BensonPang
author_rank: Newbie
timestamp: April 18, 2025, 01:11:28 am
content: Hi,I want to calibrate the IWATSU CS-3300 curve tracer. But I cannot find the calibration manual from website. Can anyone provide it for me ?regard
Weston Engineering Notes: Weston Standard and Normal Cells construction and use  - Page 1
Forum section: electronics / general

author: tggzzz
author_rank: Super Contributor
timestamp: April 14, 2025, 10:04:52 pm
content: Bitsavers has made available good quality scans of the Weston Engineering Notes from 1946 to 1952.http://bitsavers.org/test_equipment/weston/Weston_Engineering_Notes/"VOLUME 1 NUMBER 3, WESTON'S CADMIUM CELL A True Standard of Comparison"http://bitsavers.org/test_equipment/weston/Weston_Engineering_Notes/Weston_Engineering_Notes_V01_N03_194606.pdf"VOLUME 3 NUMBER 6, WESTON STANDARD CELLS AND THEIR APPLICATIONS"http://bitsavers.org/test_equipment/weston/Weston_Engineering_Notes/Weston_Engineering_Notes_V03_N06_194812.pdfThe latter mentions a type new to me: The Pyrometer Cell."The Pyrometer cell is chemically the same as the Standard cell but is smaller in size being 12.5 mm (0.5 inch) in diameter. It is supplied unmounted but packed in individual cartons. These cells were developed specifically for use as a reference standard in balancing-type potentiometer circuits such as those used in potentiometric recorders, controllers and other devices using similar circuits."

author: Overspeed
author_rank: Frequent Contributor
timestamp: April 16, 2025, 09:01:13 am
content: HelloThe Pyrometer Cell is just a small size cell for bespoke purpose .I link a pictureThanks for linksRegardsOS

author: HighVoltage
author_rank: Super Contributor
timestamp: April 16, 2025, 09:08:45 am
content: What a nice collection!Thanks for sharing

author: tggzzz
author_rank: Super Contributor
timestamp: April 16, 2025, 09:24:54 am
content: Glad you like them. There's an RSS feed if you want to see the new stuff they upload.They have added a well scanned version of an old publication, containing lovely pictures and diagrams, plus terse useful explanations. Subjects include magnetic meters of various classes, standard cells, resistors, shunts, photocells, rectifiers, electrostatic devices, tachos, and more.http://bitsavers.org/test_equipment/weston/E-3_E_The_Instrument_Sketch_Book_1956.pdfA similar document with more depth ishttp://bitsavers.org/test_equipment/weston/TM-101_Miller_-_A_Discussion_of_Electrical_Measuring_Instruments_1956.pdfThere's also an index to the engineering notes series in that directory (but I can't be bothered to find it again!).
Hathaway Beta Calibrator Model 235  - Page 1
Forum section: electronics / general

author: Taimer81
author_rank: Regular Contributor
timestamp: April 10, 2025, 08:42:20 am
content: Hello!Please help me find the "Master Cal IMMS" program for the "Beta Calibrator Model 235". Mee need to use it to calibrate the device, as far as I understand, this can be done with it.It's old and needs to be taken care of.Thanks.

author: Halcyon
author_rank: Unknown
timestamp: April 11, 2025, 02:04:30 am
content: Duplicate post.
New owner of a Keithley 2002 - Page 1
Forum section: electronics / general

author: derZockerMP
author_rank: Regular Contributor
timestamp: April 19, 2025, 08:47:20 pm
content: Hello, finally i got a new toy to enter the world of 8,5 digit Multimeter. A like new Keithley 2002.Any tips and tricks to make first tests?First thing was to compare it to my other meters (K2001, K2010) against K2004 SMU. Also a precision Caddock resistor was used.Second is a long time measurement other night with a LM399 refrence.What i often saw is input current measurment. Will try it with my electrometer later.My unit sadly has no MEM2 option. Has anyone a source for Dallas RAM?Best Regards

author: maat
author_rank: Regular Contributor
timestamp: April 20, 2025, 02:18:04 am
content: I installed this memory IC into my K2002:https://www.mouser.com/ProductDetail/Analog-Devices-Maxim-Integrated/DS1248Y-70IND%2b?qs=LHmEVA8xxfZm0DOGFdxJmQ%3D%3DWow, that price has gone up. I paid 35 € 4 years ago.Anyway, bump the firmware while you have it open. It is a spectacular meter. Noisier than a 3458A, but rock stable. Mine has been back and forth to calibration. Always coming home in spec. No adjustments necessary...Enjoy it.
Agilent 4263b calibration Software - Page 1
Forum section: electronics / general

author: engiadina
author_rank: Contributor
timestamp: February 07, 2016, 12:48:55 am
content: Basically the question is ... does someone has the required software for this?I happen to have the calibration manual but for adjustments this software is necessary.Thanks for your help already,engiadina

author: picburner
author_rank: Frequent Contributor
timestamp: March 31, 2025, 11:19:08 am
content: I understand that it's been a long time since this post but if possible could you share this manual?

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 31, 2025, 04:36:19 pm
content: I added all the manuals I have here. Hope that helps.I am also looking for the adjustment software. I'm about ready to write my own from scratch in Python at this point...

author: picburner
author_rank: Frequent Contributor
timestamp: April 09, 2025, 05:34:40 am
content: That program will never come out. But even if it did, it would be completely useless because it is acompiled executableand only runs on HP 9000 200/300 workstations.The calibration manual ,if it really exists, might help us figure out how to create a program from scratch.

author: TERRA Operative
author_rank: Super Contributor
timestamp: April 09, 2025, 11:00:48 am
content: The 4263B Service manual has some info on the calibration steps, but it's essentially just an instruction to "use the software and follow the prompts" kind of thing.The option unlock software would be a separate thing to the cal software. I'm almost thinking to look at the memory locations of the cal constants, do some poking to figure out what is what and then reverse engineer the cal process (I suspect it'll be the usual offset and span values per range common to most test gear).But that's a job for when I get time.............
Ground reference plane in ESD test setup (IEC 61000-4-2) - Page 1
Forum section: electronics / general

author: jusaca
author_rank: Unknown
timestamp: April 02, 2025, 09:02:22 am
content: We are just starting to build a small place at our office to do some rough pre-compliance ESD testing.The test setup in the IEC 61000-4-2 describes that the GRP (ground reference plane) should be connected to protective earth (see screenshot).QuoteThis makes sense for grounded equipment, but it is also the intended test setup for battery powered devices:QuoteWhat influence does a PE connection of the GRP have for the test of battery powered devices? The ESD generator is still connected to the GRP, so the loop from generator, over the EUT to the GRP and back to the generator should not be influenced by a connection to PE? I also can't see any safety issues when GRP is not connected to PE.So, does anybody know what the rational is for connecting the GRP to PE in battery powered applications?

author: EC8010
author_rank: Frequent Contributor
timestamp: April 02, 2025, 09:39:11 pm
content: I think what they're getting at is that there should be a large RF reflective surface connected to ground. We wondered about setting up such a fixture. In the end, we found that (for mains powered equipment) radiated susceptibility was the most problematic, followed by conducted emissions. I imagine some assumptions are made about battery powered equipment and a user holding it, and therefore coupling it to ground (that ground plane).

author: Andreas
author_rank: Super Contributor
timestamp: April 03, 2025, 05:19:00 am
content: Quote from: jusaca on April 02, 2025, 09:02:22 amPE (protecting earth) is always safety.Do you really believe its funny to step on an 20 kV charged (over time) GRP?-> calculate the impedance of a 1 m cord @300 MHz of a ESD discharge against the parasitic capacitives.regards Andreas

author: jusaca
author_rank: Unknown
timestamp: April 03, 2025, 07:41:21 am
content: Quote from: EC8010 on April 02, 2025, 09:39:11 pmBut this would matter primarily in EMC tests, not in ESD tests? Or am I wrong with that assumption?Quote from: Andreas on April 03, 2025, 05:19:00 amMaybe I have a knot in my brain, but connecting the GRP to PE should make no difference for a charge on the plate? The ESD generator is isolated from mains and PE, so any voltage difference coming from the generator will not be influenced by connecting the GRP to PE?
what do you think about Sparkfun's new GPSDO? - Page 1
Forum section: electronics / general

author: slburris
author_rank: Frequent Contributor
timestamp: March 26, 2025, 05:02:14 pm
content: I'm referring to their new $2500 product:https://www.sparkfun.com/sparkpnt-gnss-disciplined-oscillator.htmlI'm sitting on a couple of Thunderbolts, so I don't really --need-- another GPDSO, and as a hobbyist, it reallywould need to be about 1/4th of the price to be interesting to me. Any opinions on where this would landin the GPSDO universe? Does the performance justify such a price when there are much lower cost"good enough for a lot of applications" GPSDOs out there? And yes, I know the SparkFun unit talks to multipleconstellations, so it's really a GNSSDO instead of a GPSDO. Does talking to multiple constellations at the sametime really help for this?I'm kinda intrigued that they are using a fancy TCXO, instead of an ovenized oscillator. Hmm, what if youenclosed the SiT5358 chip and temperature stabilized it yourself?Huh, I went and skimmed the datasheethttps://www.sitime.com/products/super-tcxos/sit5358-- if this partweren't so expensive, I'd play with the DCTXCO version. Maybe prices will come down someday.

author: Smoky
author_rank: Frequent Contributor
timestamp: March 27, 2025, 12:35:13 am
content: I watched Sparkfun's video about the disciplined oscillator.If I have it right, the unit is $2500 but you must also pay their monthly network fee of $1,000

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 27, 2025, 12:38:52 am
content: Quote from: Smoky on March 27, 2025, 12:35:13 amIf you actuallyneedthose extra 4 nS, $1K isn't going to be a big deal...

author: MIS42N
author_rank: Frequent Contributor
timestamp: April 02, 2025, 11:53:40 pm
content: Just from the specifications, you get what you pay for. The GNSS receiver is the key, Digikey has it at $745. As a positioning device, they are accurate down to a few cm. As a timing device, it's going to provide timing pulses consistent within 1ns (light travels 30cm in 1ns). The oscillator specs 1ppb/°C and 1.5e-11 ADEV at 10 seconds are not brilliant, good OCXOs are better. The pulling of the digital control version is quotes as 5 parts per trillion, which sets the lower limit on the accuracy of the output frequency.So it's a fairly conventional design made from top quality components with lots of bells and whistles. If your requirement is for accurate timing, good choice. If you want accurate frequency, it should perform well in a stable temperature environment. The limit may be set by that ADEV figure - 1.5e-11. For less than a tenth the price, you should be able to get a GPSDO that delivers 1e-10 (10MHz±1mHz). Which for most hobby purposes I think is 'good enough'.
Labview "Guildline" and "Measurement International" - Page 1
Forum section: electronics / general

author: NANOJOLTS
author_rank: Contributor
timestamp: March 13, 2025, 03:47:31 pm
content: Labview seems to be utilized by "Guildline" and "Measurement International" with their DCC equipment?Anyone with more information/details?

author: D.Burnette
author_rank: Contributor
timestamp: April 02, 2025, 11:15:51 pm
content: Probably running an embedded controller or FPGA?https://www.ni.com/en/shop/labview/introduction-to-labview-for-embedded-systems.htmlIt wouldn't be my first choice, but I guess if I had automated or semi-automated development systems run with labview, it would be an easier transition than re-writing it in C/C++.The 6640Q seems to run both Win10, and an embedded something.Interesting thing to dig into...Planning on modifying one?
Interesting new part - precission matched 32 channel high voltage divider - Page 1
Forum section: electronics / general

author: daqq
author_rank: Super Contributor
timestamp: March 30, 2025, 07:21:20 pm
content: From Analog Devices there's a weird new part:https://www.analog.com/en/products/ad45336.htmlA 32 channel high voltage (to 225V per input) divider, with stable ratios. I mean, weird, but cool

author: Gyro
author_rank: Super Contributor
timestamp: March 30, 2025, 08:10:45 pm
content: According to the application document, it's intended as a monitoring companion for their AD45335 14 bit 32 channel 200V DAC. Seems to make sense...https://www.analog.com/en/products/ad45335.html
Fresh from fleabay, Other Biddle 9 decade resistor box, photos - Page 1
Forum section: electronics / general

author: NANOJOLTS
author_rank: Contributor
timestamp: March 19, 2025, 08:47:20 pm
content: Fresh from fleabay, Other Biddle 9 decade resistor box, photosBiddle cat. 71-634 Stackpole 3 poles in parallel and 4 wire posts, 0.01 to 1Meg, is that 2,357,947,691 settings?Stackpole 304 86 45
Fluke 5522A MFC Flash Rom - Page 1
Forum section: electronics / general

author: Jetecnet
author_rank: Contributor
timestamp: May 30, 2024, 02:05:02 pm
content: Anyone out there got the Flash ROM dumps (A9 CPU card U5 and U6) for the 5522A MFC?Serial diags state Flash Rom is bad.TIAJC

author: FUTURE
author_rank: Newbie
timestamp: February 09, 2025, 11:56:55 am
content: Hello, I have the same needs as you. Have you found them?

author: Jetecnet
author_rank: Contributor
timestamp: February 09, 2025, 09:52:24 pm
content: No, Fluke supplied a replacement CPU card.

author: FUTURE
author_rank: Newbie
timestamp: March 11, 2025, 11:27:22 am
content: It's both regretful and fortunate. Once we have the board, we can back it up in advance。If you have backed up the firmware, could you please provide me with a copy.thanks

author: Jetecnet
author_rank: Contributor
timestamp: March 11, 2025, 01:08:58 pm
content: We didn't pull the data off the new card.

author: FUTURE
author_rank: Newbie
timestamp: March 16, 2025, 02:34:12 am
content: THANKS.
keysight E4980A LCR meter, dc bias level accuracy - Page 1
Forum section: electronics / general

author: BensonPang
author_rank: Newbie
timestamp: March 12, 2025, 12:30:23 am
content: Hi,On the E4980A LCR meter keysight calibration report, "Amp mode: x1" and "Amp mode: x8" are mentioned on dc bias level accuracy test ( see attachment ). I read through the manual, but still not find what Amp mode x1 x8 refers to. Can anybody help ?Good luck.
HP/Agilent 8481B power sensor calibration requires high power? - Page 1
Forum section: electronics / general

author: wb0gaz
author_rank: Frequent Contributor
timestamp: April 03, 2025, 07:44:30 pm
content: Have a HP 8481B sensor and a 25 watt 30 dB attenuator of the type normal paired (by serial number) with the sensor, however, the two devices do not share same serial number; this pair was pulled together in separate purchases a long time ago. For that reason, the calibration correction factors on the 8481B sensor are moot.When a 8481B (sensor and attenuator) are calibrated, I understand that the two parts are calibrated as a unit, with the calibration source feeding the 25 watt attenuator, so that return loss between the sensor and attenuator are part of the overall response measurement.What is the required power level when calibrating this setup? At 0 dBm, the sensor will be very low in it's input power operating range. To get 0 dBm to the sensor, I believe 30 dBm (1 watt) would be needed. Generating 1 watt at 18 GHz is doable but would require additional equipment (than a typical generator such as HP 8672-8673 type whose output is at most 5-10 dBm.)I'm asking this not so much for a DIY solution, but rather how to know the expected calibration scenario when/if the pair is farmed out to a cal lab.Thanks for any info/documentation that guides this decision?Dave
IEC 60601-1-2 power quality measurements with scope - Page 1
Forum section: electronics / general

author: jrmymllr
author_rank: Regular Contributor
timestamp: March 06, 2025, 03:13:18 pm
content: Does anyone know of a way to assess (even if approximately) a device's compliance with the voltage fluctuations and flicker test by capturing voltage and current data with a scope and analyzing it with some software tool? The instruments to do this are quite expensive especially if the load draws a lot of power.Seems like there would be something that I could load CSVs into that are exported from a scope.

author: 2N3055
author_rank: Super Contributor
timestamp: March 06, 2025, 05:37:35 pm
content: Siglent SDS 800xHD has power analysis option...
Fluke 724 calibration linking to pc  - Page 1
Forum section: electronics / general

author: calenguk
author_rank: Newbie
timestamp: March 03, 2025, 09:39:35 pm
content: HiI need to link a Fluke 724 to a PC to adjust it. The Fluke 724 is an older version with NO password. How can I link it to a PC ? I do have the Fluke RS232 cable but how do I get it to talk to a PC ?Fluke use Met Cal but its expensive. Hyper terminal used to work but no longer on modern computers.

author: Kean
author_rank: Unknown
timestamp: March 04, 2025, 02:11:58 pm
content: As you mention HyperTerminal, I presume you know the commands you need to type to run the process manually.There are many alternative terminal emulators for Windows. I mostly use PuTTY and RealTerm myself, but there is also Termite, TerraTerm, and others.In fact, I think HyperTerminal is still available, just not from Microsoft.
found this about the cheap gpsdo units from aliexpress - Page 1
Forum section: electronics / general

author: ME
author_rank: Frequent Contributor
timestamp: March 03, 2025, 11:08:44 am
content: Hope its of use to folks?.

author: ME
author_rank: Frequent Contributor
timestamp: March 03, 2025, 11:09:58 am
content: and a few links.https://github.com/dankar/gpsdo-fw?tab=readme-ov-filehttps://github.com/dankar/gpsdo-fw

author: Kean
author_rank: Unknown
timestamp: March 03, 2025, 12:41:41 pm
content: There is a multi-page thread alreadyhttps://www.eevblog.com/forum/testgear/10mhz-gpsdo-by-bh3sap/
Heads-up - 2025 Metrology Society of Australasia Conference (Sydney, Australia) - Page 1
Forum section: electronics / general

author: binary01
author_rank: Contributor
timestamp: February 20, 2025, 03:32:57 am
content: Just a quick post for Australasian metrologists, or anyone travelling this way in August, to let you know about the Metrology Society of Australasia (MSA) conference in Sydney, AU from25-28 August, 2025.I always attend and thoroughly enjoy it, with a chance to see lots of shiny new test equipment on displayKeynote speakers this year include the chief metrologist from NIST, Dr James K. Olthoff, among others. Registration opens early March.More information here:https://metrology.asn.au/events/msa-conference-sydney-aus-25-28-august-2025/I hope to see some of you thereIf you're coming along, feel free to send me a PM so I can find you there.
For sale in France : Potentiometer Universal Leeds & Northrup Type K-3 - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: February 19, 2025, 08:55:06 pm
content: HelloIf some one is interested , make offerhttps://www.leboncoin.fr/ad/collection/2839727290RegardsOS
Wavetek 9100 ( Current problem ) P03.049 P03.042 P08.002 P03.036 P03.020 P03.002 - Page 1
Forum section: electronics / general

author: Ugur
author_rank: Regular Contributor
timestamp: February 17, 2025, 06:03:22 am
content: Hello everyone,Many topics have been opened about 9100 but the problems experienced are different.Maybe someone has experience with this error.A faulty application may have been made and a voltage may have been applied to the current outputs of the device. I have replaced many faulty parts in the current line and the device is now opening.But there is a problem that I cannot detect.When it is first opened, it gives 6 error messages and none of the buttons work. I am working on the device by bypassing the self-test. Volt, Ohm works without any problems.It produces current values ​​up to 3A but when we switch to high range after 3A.For example, it produces 40A at 4A.The problem is that there is 10V in +7V5. (There is -10V in -7V5.)There is no problem in Low range but when we switch to High range, this drops to +5V level.(NE5534N) While there is no voltage at the inputs of U305, 2-3V is generated at the output pin. This goes to the input of U303.I get 6 line messages as a result of the fast test. There is no big difference according to the measurement results.I get more errors as a result of the full test, but most of them are small microvolt level errors. In other words, they can be ignored and corrected.Do you have any suggestions regarding this error?Replaced parts:R309 0.1 OHMU303 DG211U305 NE5534NU304 OPA602U301 DG411U302 DG211U308 LTC1150U306 OP27U401 TLE2082U402 CA3140U403 MC34082U405 LM2903NW512 TIP31CD523-524-525-526 BYV42E-200U802 7400Broken path from R316 to chassis repaired.*****Problem solved.
Hp 34420a probe - Page 1
Forum section: electronics / general

author: MARCEBELE
author_rank: Contributor
timestamp: March 12, 2025, 11:42:04 am
content: Hi all,I strike a gold on ebay and buy this use HP 34420a for only 250 usd!!!I plan to use this but don't have the probe and seeing it goes for 180 to 300 on ebay i plan to Build one my selfIs anyone know the name of the female connector and where to buy them, I like to DIY them

author: picburner
author_rank: Frequent Contributor
timestamp: March 12, 2025, 12:11:21 pm
content: The connector is a LEMO code FVN.1S.304.CLYC37ZI bought it fromMouserand it is not cheap.There are also cheaper versions that however affect the performance of the instrument.You will also need another one to connect in short circuit to perform the zeroing of the instrument.

author: ch_scr
author_rank: Frequent Contributor
timestamp: March 12, 2025, 12:18:36 pm
content: There are clone LEMO on Aliexpress. The "0S" I bought were of good quality, but I did not try to mate them to original ones.This Sellerhas "1S FFA Plug 4 Pin". They are not bare copper though, gold plated instead so maybe not ultimate performance.Sure cheap enough to give it a try IMHO.

author: MARCEBELE
author_rank: Contributor
timestamp: March 12, 2025, 01:09:52 pm
content: Thanks for sharing.Looking at it again I may want to sold this, It's good device but I might never use it for what it's capable off, i mainly repairing a laptop or a phone this thing is not suitable for this task and way overkill for it.buy this impulsively because of the price without thinking what will I use this for.The device seem to be in good physical condition and the screen is still bright and no dimming or brighter spot.If anyone is interested I like to sell this😁😁

author: CalibrationGuy
author_rank: Unknown
timestamp: March 13, 2025, 02:25:34 am
content: Create a "For Sale" post in the wanted/for sale section if you want to sell it. I'm sure you won't have a problem selling it at a decent price.TomG.
4737-A20, Leeds & Northrup Manual? - Page 1
Forum section: electronics / general

author: r6502
author_rank: Regular Contributor
timestamp: January 22, 2024, 12:29:40 pm
content: Hello all,I 'm just looking for a manual / schematic for a 4737-A20, Guarded Wheatstone Bridge from Leeds & Northrup.I did not found a online PDF from the device. On Ebay, I found a manual but no shipping option to Germany, and for about 42$, close to what I payed for the device.Any links to PDF are welcome.Guido

author: F4
author_rank: Contributor
timestamp: February 02, 2025, 02:32:43 pm
content: Here:https://bama.edebris.com/download/leads_and_northrup/4737-a2x/L&N%204737%20A20_A21.pdf
Datron 1271 Replacement right side display - Page 1
Forum section: electronics / general

author: View[+]Finder
author_rank: Unknown
timestamp: January 29, 2025, 08:50:14 pm
content: https://www.eevblog.com/forum/repair/replacement-display-for-datron-12711281-and-possibly-for-49504920-as-well/msg5795331/#msg5795331New information: documentation for OLED display

author: View[+]Finder
author_rank: Unknown
timestamp: January 30, 2025, 10:36:31 pm
content: PM to @picburnerQuoteThanks @picburner for the jpg below
IES ISW8000 - Page 1
Forum section: electronics / general

author: lionelkjh
author_rank: Frequent Contributor
timestamp: January 27, 2025, 04:44:09 pm
content: Good evening everyone! I am looking for a spare part for the PIC 16C55-RC/SP microcontroller on an IES ISW8000 table wattmeter; it is on the front panel, and the reference is: U1.....Does anyone have it? Thank you for your answers

author: MiDi
author_rank: Frequent Contributor
timestamp: January 27, 2025, 07:22:37 pm
content: If you only need spare of the µC, that part is available from a couple of distributors.

author: lionelkjh
author_rank: Frequent Contributor
timestamp: January 28, 2025, 11:38:04 am
content: Hello; I am looking for the programmed microprocessor, not blank..... Do you know anyone who has it?
DAC1220 REF Schemtaic +-10V - Page 1
Forum section: electronics / general

author: derZockerMP
author_rank: Regular Contributor
timestamp: January 16, 2025, 05:09:29 pm
content: Hello, I want to design a schematic to output a 20-bit voltage ranging from +10V to -10V for a voltage source. The output of this circuit will be used for an output stage that amplifies the voltage to ±100V in four different ranges. What do you think about this rough schematic? Is there a way to simplify the circuit (by removing U8B) to achieve the ±10V output?Best Regards

author: Kleinstein
author_rank: Super Contributor
timestamp: January 16, 2025, 07:55:18 pm
content: The reference and the DAC output are on theory low impedance. In principle one may get away with a simple 1 OP-amp difference amplifier between the output and ref. voltage. However loading the reference will add some nonlinear error. It is also not clear how well the output handles loading: this can also add errors. Loading could be reduced by 2 additional, but less critcal amplifiers to provide most of the current (kind of virtual class A). So one would get more parts, but fewer critical parts.

author: laichh
author_rank: Regular Contributor
timestamp: January 17, 2025, 01:22:37 am
content: May take a look in the DAS11001B datasheet, section 8.2.1 Source Measure Unit (SMU).

author: derZockerMP
author_rank: Regular Contributor
timestamp: January 20, 2025, 02:12:49 pm
content: Ok thanks, I will try it out on a prototype Board. Should I use guard traces around some nodes? Normally not because they are all Low Impedance Right?

author: Kleinstein
author_rank: Super Contributor
timestamp: January 20, 2025, 02:24:29 pm
content: The 2 capacitor pins at the ADC chips are maked to want a guard (e.g. ground or ref.). At least it would not really hurt.
Advantech r6581 worth for the price ( used ) ? - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: February 16, 2025, 06:51:19 pm
content: HelloDoes that worth for the price as they are quite cheap as used and quite common on the used / surplus marketa subject have been openedhttps://www.eevblog.com/forum/metrology/advantest-r6581-8-5-digit-dmm-mini-teardownrepair/Other solution is to purchase a new 7.5 digit Hioki 7276 with 9 ppm , I need only a voltmeter but perhaps the R6581 is a solution ?RegardsOS