hybridfree/eevblog-posts huggingface dataset:
Can anyone help identify this SMD device?  - Page 1
Forum section: electronics / general

author: brian_mk
author_rank: Regular Contributor
timestamp: October 03, 2025, 01:03:56 pm
content: I'm not sure if this is the best forum for this question but here goes...The attached photo is a hard disk control board (part no '4952 K') from a failed Seagate Barracuda 8TB drive (ST8000DM0004).A simple test with a multimeter suggests that what appears to be a transistor has failed.There is an open circuit across two of the pads. i.e. the middle pad at the top (collector?) and the left hand pad at the bottom (base?).It may be a bipolar transistor or a FET of some sort.The device is outlined in red in the photo.The number marked on the device looks like 'TR1' followed by either a strange looking '7' or a 'J' rotated by 90 degrees.Can anyone help identify the device?I am hoping to replace it and repair the drive.I have discovered you can buy complete replacement PCBs (Part No: 100784953) from places like Aliexpress BUT apparently the BIOS chip has to be swapped over so that it matches the rest of the drive. It is a multipin SMD device. Swapping it is beyond my capabilities - I don't have the tools or the skill.After a lot of searching around, I suspect the device is an N-Channel Power Mosfet NTR4501N.In that case the top center pad is the drain and the lower left pad is the gate.Hence my thought that the device was faulty is probably incorrect and I will be unable to repair the drive.

author: thm_w
author_rank: Super Contributor
timestamp: October 03, 2025, 10:02:18 pm
content: https://forum.allaboutcircuits.com/threads/can-anyone-help-identify-this-smd-device.208291/Check diodes, check for shorts on any of the ceramic capacitors.Buy hot air station to swap the eeprom, if you can't do it, get someone to do it for you.
Sonsivri forum - Page 1
Forum section: electronics / general

author: houly
author_rank: Contributor
timestamp: October 02, 2025, 09:10:59 pm
content: HelloI can't access to sonsivri forum, could you please confirm me if the site is down please ?https://www.sonsivri.to/forum/index.phpthanks for your help

author: RoGeorge
author_rank: Super Contributor
timestamp: October 02, 2025, 09:26:21 pm
content: Sometimes the status might depend of one's geolocation. This time it looks like the website is down.When in doubt, it is possible to test the appearance from all around the world, search for "is it down":https://duckduckgo.com/?t=ffab&q=is+it+down

author: thm_w
author_rank: Super Contributor
timestamp: October 02, 2025, 09:49:44 pm
content: Looks like it was last archived back in August sometimehttps://web.archive.org/web/20250812023755/https://www.sonsivri.to/forum/index.phpSo may have died after that.I don't remember them going to invite only, maybe I never had an account.
Alibaba messages to suppliers using LLMs - Page 1
Forum section: electronics / general

author: Psi
author_rank: Super Contributor
timestamp: September 30, 2025, 12:52:02 am
content: Just a heads up.I just messaged a seller on Alibaba to get a new order underway and it was obvious, based on how instant they replied which was less than typing speed, that I was talking to a LLM at first before the real person came online.

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: September 30, 2025, 03:35:00 pm
content: Talking to LLM chatbots is the new normal.Expedia has one which is beyond terrible. All niceties and sweet talk, but refuses to help you. Very politely “it” will tell you to go and fuck yourself, your money is gone for good.

author: Nominal Animal
author_rank: Super Contributor
timestamp: October 02, 2025, 07:20:19 am
content: Quote from: UnijunctionTransistor on September 30, 2025, 03:35:00 pmWhat do you mean, terrible? It is exactly what all companies want from their customer-facing "staff", and why customer service personnel is being replaced by LLMs!Oh, you mean terrible forhumans and customers? Who cares! Money talks, 'itch.</End Sarcasm>

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: October 02, 2025, 04:14:10 pm
content: Indeed, money talks.And those pesky humans require healthcare, vacations, meal breaks, home/work balance, and sometimes even ask for pay raises.
What is this white SMD component on a SIM800L red module ? - Page 1
Forum section: electronics / general

author: alainz
author_rank: Newbie
timestamp: September 26, 2025, 01:57:17 pm
content: Hello!Does anyone know what this white component is, and what its role is in the SIM800L module circuit?Thanks in advance!

author: RoGeorge
author_rank: Super Contributor
timestamp: September 26, 2025, 04:18:44 pm
content: Looks like an RF capacitor. Most probably it is there for impedance matching between the antenna and the radio module.

author: thm_w
author_rank: Super Contributor
timestamp: September 26, 2025, 08:30:23 pm
content: Its a ~47pF power supply decoupling capacitor. In parallel with the larger ceramic (0.1-20uF) and even larger tantalum (470uF). Whether its of much use is up to debate.The module RF output goes directly to the ufl connector. Though they do show impedance matching caps in the ref document, they never actually use them:https://cdn-shop.adafruit.com/product-files/1946/SIM800HL-TE_Schematic+and+PCB_Reference+Design_V1.00+%281%29.pdfhttps://circuitdigest.com/microcontroller-projects/interfacing-sim800l-module-with-esp32

author: alainz
author_rank: Newbie
timestamp: September 27, 2025, 11:38:37 am
content: Thanks a lot to everyone who replied and commented — your input really helped me look deeper into this.After tracing the board more carefully, I discovered the following:The small MLCCis connected betweenVCC of the SIM cardholder andGND. So it’s just a local decoupling capacitor for the SIM supply.The white/thicker SMD partis connected between theSIM I/Oline andGND. This makes sense as anESD protection device(TVS), or possibly part of the recommendedSIM interface filtering(TVS + R +C).I’ll add a photo showing these connections for clarity. My next step is to desolder both parts and measure them to confirm (capacitance for the MLCC, diode behavior for the TVS). Once I have the results, I’ll post them here as the final update.Thanks again for the guidance!

author: alainz
author_rank: Newbie
timestamp: October 01, 2025, 12:43:21 pm
content: Update / Conclusion:Thanks again to everyone for the help. I desoldered the two parts and measured them:The small brown MLCC is 1 µF, used as a decoupling capacitor on the SIM VCC pin.The thicker white SMD is also a capacitor (~22 pF), not a TVS. It’s part of the SIM interface RC filter (22 Ω + 22 pF to GND) recommended in the SIM800L datasheet.On the cheap red SIM800L board, the 22 Ω series resistors are omitted (probably to save cost), so only the capacitors are left. On the bigger module version, both the resistors and capacitors are present, exactly as shown in the reference design.So in short:1 µF MLCC = SIM VCC decoupling22 pF MLCC = SIM I/O line filtering
Understanding the RF Exposure SAR Level - Page 1
Forum section: electronics / general

author: simoman
author_rank: Newbie
timestamp: October 01, 2025, 01:06:53 pm
content: HelloI'm doing some research on the RF Exposure SAR levels of different devices. I'm struggling to understand this FCC document to figure out what the RF Exposure SAR level is for the Meta Quest 3:https://fcc.report/FCC-ID/2AGOZ-S3A/6639597.pdfPage 25 lists three different values, is the first one listed: 1.19 the SAR value to go by?Thanks!!

author: radiolistener
author_rank: Super Contributor
timestamp: October 01, 2025, 08:47:30 pm
content: Quote from: simoman on October 01, 2025, 01:06:53 pmAt a glance:First one is for WLAN 2.4GHz + WLAN 5GHz + nRFSecond one is for WLAN 2.4GHz + WLAN 6GHz + nRFThird one is for WLAN 5GHz +Bluetooth + nRFSo it depends on the combination you're using.

author: simoman
author_rank: Newbie
timestamp: October 02, 2025, 02:27:46 am
content: HiIt would be either WLAN 2.4GHz + WLAN 5GHz + nRF or WLAN 5GHz +Bluetooth + nRF(I'm confused as to which one for certain as bluetooth is applicable regardless)I'm confused by the report, it gives lower readings the high the GHzI'm not even entirely sure page 25 is the correct section to be looking at to figure out the figure for a device using a typical standard wifi connection
Struggling to find PCB design work, am I looking in the wrong places? - Page 1
Forum section: electronics / general

author: eescuve
author_rank: Newbie
timestamp: September 24, 2025, 10:20:33 pm
content: Hi everyone,I’m an electronics engineer focused on PCB design with +5 years of experience, trying to get remote freelance projects. So far I’ve tried:Upwork → many clients with unclear requirements or very low budgets.LinkedIn → I share design videos (6k+ views) but haven’t had project inquiries.Questions:Where do freelance PCB designers usually find clients?Is Upwork worth the effort, or should I focus on other hardware communities?Any guidance from people who’ve been through this would help a lot.Thanks!

author: richard.cs
author_rank: Super Contributor
timestamp: September 25, 2025, 01:07:13 pm
content: In my country this kind of work is not really done by PCB designing freelancers, but by small "design consultancies", companies with 3-10 people who take on and manage the whole project. Sometimes just the electronics, sometimes the whole thing. I worked in one for 8 years, and now contract to a different smaller one as my second / side job.

author: nctnico
author_rank: Super Contributor
timestamp: September 25, 2025, 08:34:40 pm
content: You need a portfolio to show your work. Linkedin can be useful. And this forum (the work wanted and jobs sections) can be a good source for projects. But don't expect miracles. It takes time to built a reputation.If you can't get enough work, then it could be worthwhile to work at a company offering design services. It helps to make your name and you can gain more experience.

author: tom66
author_rank: Super Contributor
timestamp: September 25, 2025, 11:19:23 pm
content: I second @richard.cs. We do not work directly with PCB contractors, but use an agency. That agency charges about 20% more than a direct contractor would charge, but gives us access to stackup/impedance consultants (POLAR software is like $10k a seat), production engineering, and plenty of capacity where we need multiple engineers. It's effectively turnkey for prototyping.I would suggest you look at these agencies and ask if they are willing to take you on. You will probably not get paid as much, but you will likely get a consistent flow of work, if you are good.Be aware you will often need to bring your own license, and software like Altium isn't cheap. In my experience relatively few companies are using open source tools, so you need to budget a few thousand a year in software licensing.
Lumafield 18650 report - Page 1
Forum section: electronics / general

author: madires
author_rank: Super Contributor
timestamp: September 25, 2025, 11:05:03 am
content: Media:- X-ray scans reveal the hidden risks of cheap batteries -https://www.theverge.com/news/784966/lumafield-x-ray-ct-scan-lithium-ion-battery-risks-manufacturing-defect- Study Reveals 1 in 13 Low-Cost Lithium-Ion Battery Cells Could Have Dangerous Defect -https://www.morningstar.com/news/pr-newswire/20250924ne80841/study-reveals-1-in-13-low-cost-lithium-ion-battery-cells-could-have-dangerous-defectReport (requires contact info):-https://www.lumafield.com/battery-report

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 26, 2025, 04:05:10 pm
content: Here's the report without any need for register:https://transfer.it/t/oK7dLkwBGRLR

author: thm_w
author_rank: Super Contributor
timestamp: September 26, 2025, 08:21:48 pm
content: TLDR: if you are buying 18650 cells, source major brands from a reputable shop instead of Amazon/temu.eghttps://www.18650batterystore.com/
Looking For Pocket Guide - Page 1
Forum section: electronics / general

author: BILLPOD
author_rank: Frequent Contributor
timestamp: September 26, 2025, 08:08:16 pm
content: Good Morning Fellow EEVblog Members, I'm looking forAnalog Engineer's Pocket Reference, Fifth Editionput out by Texas Instruments, copyright 2019. I'm looking for a printed version. Duck Duck Go or Google haven't been much help.Thanks for giving it any thought.
Someone is attempting a full scale flying delorian... - Page 1
Forum section: electronics / general

author: BrianHG
author_rank: Super Contributor
timestamp: July 01, 2024, 03:37:44 pm
content: Hope he makes it painted silver...

author: tom66
author_rank: Super Contributor
timestamp: July 01, 2024, 04:40:44 pm
content: The real question is will it run off food waste put in an old Krups coffee maker?

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 01, 2024, 08:51:16 pm
content: Fun idea, I wish I had the same budget to put into something useful...

author: Gyro
author_rank: Super Contributor
timestamp: July 01, 2024, 09:20:16 pm
content: I remember seeing something like that on BBC Top Gear years ago - This one was helpedmassivelyby mostly being a balloon filled with Helium, with small steering and propulsion fans. It looked quite impressive though...

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 01, 2024, 10:12:57 pm
content: That's fun.

author: BrianHG
author_rank: Super Contributor
timestamp: September 22, 2025, 09:17:41 pm
content: Update: It flies, almost there...
Plastic identification - Page 1
Forum section: electronics / general

author: BradC
author_rank: Super Contributor
timestamp: September 18, 2025, 02:39:44 pm
content: Ok so this is a bit left field.I have a 56 year old pool which has some seam leaks in the skimmer. The skimmer is likely to be either ABS or PVC and I don’t know how to tell which. I’ve patched it twice in the last 16 years by dremelling out the seam and filling it with 24 hour Araldite. This works to keep the water in, but this particular leak is letting air in under vacuum. I could really do wth the right adhesive rather than a generic mechanical epoxy but to do that I need to know what the plastic actually is. Araldite works under pressure, but doesn’t seem to hold that well under vacuum and constant immersion.I’ve spent a few hours on the search engines but come up blank. Over the years I’ve seen some pretty impressive technical knowledge here, so I thought I might ask the question and leverage the global experience here.

author: kosine
author_rank: Regular Contributor
timestamp: September 18, 2025, 03:00:45 pm
content: Assuming it's outdoors, PVC is generally a better material, and if the pool is chlorinated that would also suggest PVC.You could try tapping it with metal implement (like a screwdriver). PVC is denser than ABS and will sound duller. ABS is a bit more tinny. If you've got anything lying around known to be made of the two, you should be able to hear the difference.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 18, 2025, 04:19:01 pm
content: One could test for the chlorine content in PVC. The test is using a hot, clean copper wire to melt / burn a little of the plastics and than hold the wire in a blue glass / alcohol flame. If halogenes are present in the plastics it would cause some green flame color from forming somewaht volative CuCl.

author: u666sa
author_rank: Frequent Contributor
timestamp: September 18, 2025, 04:35:58 pm
content: Quote

author: BradC
author_rank: Super Contributor
timestamp: September 18, 2025, 11:31:15 pm
content: Thanks all. Sounds like it would be PVC. The halide test is a great idea. As I have to scrape the seam line to expose fresh plastic for gluing I'll wind up with a fair little pile of shavings, so I'll give that a go on the weekend.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 19, 2025, 05:45:57 am
content: Flame tests can be useful and most people have what is needed to do them. When at a loss, take a sliver of real ABS and PVC to compare. Then dremel a little from the damaged area and test that. This site describes them:https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification?srsltid=AfmBOooPs53iwPiLYnGKBr-33G8aWtUZ4vxztIZKjBi_iHfjcHoAUBKu

author: magic
author_rank: Super Contributor
timestamp: September 19, 2025, 06:26:44 am
content: ABS is instantly softened by acetone.
The quartz is back on track.. - Page 1
Forum section: electronics / general

author: Cyclotron
author_rank: Unknown
timestamp: September 14, 2025, 04:07:59 am
content: In the US, in 2024, Hurricane Helene caused multi-generational level flooding and destruction in the western North Carolina area and Eastern TN. I drove I-40 through the pass about 2 months ago, and it was surreal then. I've watched the progress of the rebuild off and on, and I've watched the rebuild of the Clinchfield railroad line. The history and stories of theClinchfield lineare amazing in and of themselves.The railroad was just restored to service after nearly a year. Look at some of the videos from "Designs in Orbit" on YouTube if you want to see some of the work.Great drone footage.So what's that got to do with eevblog Forum? Quartz, high-quality quartz.https://www.railway.supply/en/csx-restores-clinchfield-railroad-service-in-western-north-carolina/https://www.thequartzcorp.comI visited The Quartz Company a few years back, and it's pretty amazing. I knew a large quantity of the semiconductor quartz came from the NC resources, but I didn't realize it was the 70% number quoted in the above article.

author: RJSV
author_rank: Super Contributor
timestamp: September 19, 2025, 09:26:38 am
content: Chocko block FULL of push advertisements !To the point where I couldn't read shit about railroad or drones....just tuktik
Return to the ML30+ mod for the BIAS TEE to run on 12 volt external supply - Page 1
Forum section: electronics / general

author: XRNSPARKER
author_rank: Newbie
timestamp: September 17, 2025, 04:55:01 pm
content: A.Z. posted about this a few years ago.. and showed the circuit diagram of where to cut the connections on the 5v to 12v converter section.I have just bought one, and opened up the BIAS TEE box, to view the pcb... the underside is covered in a black "paint" ? ? ? or some dye and it is impossible to read the actual tracks on the underside of the circuit board.Does anyone know how to remove the colour to reveal the actual circuit tracks, to enable me to cut in the right place(s) .
Python: The Documentary - Page 1
Forum section: electronics / general

author: Zucca
author_rank: Unknown
timestamp: September 26, 2025, 01:49:32 am
content: Well done documentary, reposting here because it is a interesting story about a technical open source community.

author: NE666
author_rank: Frequent Contributor
timestamp: September 26, 2025, 07:54:11 am
content: https://www.eevblog.com/forum/programming/python-the-documentary-an-origin-story/Already posted weeks ago, and in the appropriate section too.

author: Zucca
author_rank: Unknown
timestamp: September 26, 2025, 01:33:34 pm
content: I disagree, this in mainly a story about a technical open source community. Much more than a programming language evolution.This is why I posted it here.
Non leaking Durahells! - Page 1
Forum section: electronics / general

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 16, 2025, 02:24:17 pm
content: Duracell Quantum AAs in a meter I forgot about. The batteries died so I opened it. AAs with a BB date of Dec 2025, and they have zero trace of any leakage.I am impressed.

author: David Hess
author_rank: Super Contributor
timestamp: September 16, 2025, 02:46:15 pm
content: Apparently discontinued and replaced by Duracell Optimum, whatever that is.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 16, 2025, 03:08:13 pm
content: On the plus side, I peeled off the Powercheck and put it near my laptop's exhaust. Now I get a free passive analog CPU usage indicator.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 16, 2025, 11:54:47 pm
content: Quote from: Alex Eisenhut on September 16, 2025, 03:08:13 pmWait, how does that work?Doesn't that thing measure cell voltage?

author: Halcyon
author_rank: Unknown
timestamp: September 17, 2025, 12:56:32 am
content: Quote from: Analog Kid on September 16, 2025, 11:54:47 pmThey convert voltage to heat.
Milwaukee batteries cracked? - Page 1
Forum section: electronics / general

author: Cyclotron
author_rank: Unknown
timestamp: September 14, 2025, 02:53:49 am
content: I have a bunch of Milwaukee batteries, now I need to build one of these adapters so I can sit down and have a chat with my batteries over a pint.

author: thm_w
author_rank: Super Contributor
timestamp: September 16, 2025, 01:10:53 am
content: Good video, the granularity of the data they are storing is incredible.Apparently the on board BMS does support balancing, so maybe someone can figure out how to hack the firmware and enable a top balance to save packs without having to open them.I'm not sure if it can be remotely updated though.

author: Cyclotron
author_rank: Unknown
timestamp: September 16, 2025, 01:19:42 am
content: Quote from: thm_w on September 16, 2025, 01:10:53 amI think it will be great to enable folks to understand their purchased gear. And like you say, it should enable more tweaks and hacks to do things that might lengthen the battery life of the packs. I built/assembled (Kweld) a battery tab welder this past year just so I could repair packs instead of tossing them.
Looking for some technical explanation - Page 1
Forum section: electronics / general

author: paul cotter
author_rank: Regular Contributor
timestamp: September 17, 2025, 01:02:27 pm
content: We live in a forested area that is unfortunately prone to illegal dumping(fly tipping). Usually what's involved is household trash such as dirty nappies, empty dog food cans and many similar items. Recently however someone has dumped what looks a house clean out regardless of the value having gone "postal". Among many high value items is a EO EM301-T2T-DCL ev charger. On the cable going to the vehicle is a split core ct and this is the source of my query: how can a ct that encloses all conductors read anything meaningful unless the vehicle was being fed with AC with a separate return path? My knowledge of electric vehicles is close to zero but measurements have been integral to my past work and I know what a ct will and will not do. The measuring device is an old style split core ct and not a Hall device.

author: tggzzz
author_rank: Super Contributor
timestamp: September 17, 2025, 03:10:10 pm
content: Quote from: paul cotter on September 17, 2025, 01:02:27 pmWhat's a "ct"?

author: 2N3055
author_rank: Super Contributor
timestamp: September 17, 2025, 03:14:26 pm
content: Quote from: paul cotter on September 17, 2025, 01:02:27 pmThat CT (curent transformer) is measuring ground fault current. It wants for all currents to null out.If there is a current path to ground not going back to where it is supposed to go, like a person being electrocuted, then it detects that fault current and cuts power.That is same as safety RCD circuit breaker...

author: paul cotter
author_rank: Regular Contributor
timestamp: September 17, 2025, 05:48:39 pm
content: Thanks for that, I must be getting too old! as i have worked with earth fault detection on LV and MV distribution systems for decades. It is a residual current detection ct and I should not have missed that.
Chemical Liquid Deposition; Interesting research. - Page 1
Forum section: electronics / general

author: Cyclotron
author_rank: Unknown
timestamp: September 15, 2025, 06:31:09 am
content: CLD is a means to even more shrinkage in microchip manufacturing.This articlegoes over the developments out of Johns Hopkins.From the article:"Johns Hopkins scientists, working with global partners, have unveiled a new way to build microchips so small they’re invisible to the eye."
Connector identification  - Page 1
Forum section: electronics / general

author: Hornnumb2
author_rank: Regular Contributor
timestamp: September 14, 2025, 09:22:28 pm
content: Can somebody identify this connector for me some I can order one. It is smaller than a pencil eraser. Thanks Michael

author: Cyclotron
author_rank: Unknown
timestamp: September 14, 2025, 09:33:21 pm
content: Image search found this but no luck in an exact identity yet.https://www.flickr.com/photos/15239576@N00/33347912702/The title there says "AUTO-VOX video connectors pinouts" but I don't see pinouts.

author: Cyclotron
author_rank: Unknown
timestamp: September 14, 2025, 09:49:32 pm
content: I wasn't able to identify the connector as a component.Would you happen to have more information about where you got the example you have?Details such as markings, original source, intended use, and more precise dimensions.All of those can assist in identifying it.Unless, of course, someone sees it and just knows due to prior experience.

author: Hornnumb2
author_rank: Regular Contributor
timestamp: September 14, 2025, 10:04:46 pm
content: It’s just on an Amazon backup camera. I wil take some measurements tomorrow, my micrometer is at the office.

author: Cyclotron
author_rank: Unknown
timestamp: September 14, 2025, 10:31:12 pm
content: Quote from: Hornnumb2 on September 14, 2025, 10:04:46 pmCheck outhttps://www.auto-vox.com/It would seem your amazon camera is probably a rebadged auto-vox. You can probably get what you need from them.
Lelon capacitors in Meanwell din rail PSU? - Page 1
Forum section: electronics / general

author: seavan
author_rank: Contributor
timestamp: September 12, 2025, 02:58:55 am
content: I just got two different Meanwell PSUs from two different Amazon sellers. Both have Lelon caps inside. I checked serial numbers on Meanwell website and it seems legit. Both units are made pretty well with clean PCBs, Meanwell transformers. I still cannot believe Meanwell would use Lelon caps!?
Has anyone met this issue with Op-Amp? - Page 1
Forum section: electronics / general

author: MianQi
author_rank: Newbie
timestamp: September 06, 2025, 06:27:00 am
content: I tested TL061, TL062, TL071, TL072, TL081, TL082, OP07, only TL062 worked correctly in +12-12 power supply, others were all grounded -v to gnd(0v) after I set output in DC power supply, so there was no output on oscilloscope. My input was 1KHz, 20mv Vpp.

author: amyk
author_rank: Super Contributor
timestamp: September 06, 2025, 08:19:05 am
content: Fake chips?

author: Gyro
author_rank: Super Contributor
timestamp: September 06, 2025, 09:13:56 am
content: Impossible to say without knowing (preferably seeing) how you have the opamps configured. Inverting, non-inverting, feedback etc.

author: Zero999
author_rank: Super Contributor
timestamp: September 06, 2025, 03:07:35 pm
content: Quote from: MianQi on September 06, 2025, 06:27:00 amIs it a bipolar or single power supply? You first say +12V -12V power, which is bipolar, then -V to 0V which single; which is it? Post a schematic.

author: gamalot
author_rank: Super Contributor
timestamp: September 06, 2025, 03:11:09 pm
content: Post your schematics here.把你的电路图贴出来。

author: MianQi
author_rank: Newbie
timestamp: September 08, 2025, 09:30:21 am
content: Here is the schematic:

author: MianQi
author_rank: Newbie
timestamp: September 08, 2025, 09:34:48 am
content: Quote from: Zero999 on September 06, 2025, 03:07:35 pmI mean, I supply the circuit with bipolar, after I pressed "OUTPUT" on power supply, it would automatically shift to single supply - the -vcc would turn to 0v. When I supply the circuit with a 5v battery + voltage divider made by two equal value resistor, the op-amp would run correctly. This situation is just for TL061, 71, 81, 72, 82, for TL062, uA741, the power supply would supply bipolar normally.

author: alex_0331
author_rank: Newbie
timestamp: September 08, 2025, 01:19:35 pm
content: I think the negative output terminal of the power supply may be connected to the ground by a piece of metal or a wire by mistake. The correct way to use the bipolar power supply is to use 2 power output channels at the same time, and you should also make sure that the middle point of the bipolar power supply is connected to the signal input ground.

author: paul cotter
author_rank: Regular Contributor
timestamp: September 10, 2025, 02:36:57 pm
content: In a non-critical application like this all the mentioned opamps should behave identically except that the output swing achievable before clipping will vary a little. In a dc coupled circuit like shown a small dc offset could result in the output being at or near rail voltages instead of oscillating about the zero level.

author: John Coloccia
author_rank: Super Contributor
timestamp: September 12, 2025, 01:07:53 am
content: Not sure what the OP's problem is, but for anyone else...You will get strange and unpredictable results if your +/- power supplies and the rest of your circuit don't have a common reference (i.e. ground).
Farnell / CPC website down? - Page 1
Forum section: electronics / general

author: 1980s_john
author_rank: Contributor
timestamp: September 11, 2025, 07:22:35 pm
content: Hi,Is it just me, I get the attached this evening from any page other than the home page :https://cpc.farnell.comRegards,John

author: Cyclotron
author_rank: Unknown
timestamp: September 11, 2025, 07:29:19 pm
content: It is not just you.They have sent a notice of some sort of infrastructure failure impacting their site.Edit:Cpc appears up.https://downforeveryoneorjustme.com/cpc.farnell.comfarnell.co.uk shows down.https://downforeveryoneorjustme.com/farnell.co.ukEdit2:Scratch that, the web side cpc.farnell.com has an initial connection but isn't responding. So, back to, yeah, they are down.

author: themadhippy
author_rank: Super Contributor
timestamp: September 11, 2025, 07:36:53 pm
content: Quotenope.https://www.eevblog.com/forum/chat/digikey-website-bot-detection/msg6037357/#msg6037357Quotethats just the home page,try going anywere else eventually gets you the web site down page

author: factory
author_rank: Super Contributor
timestamp: September 11, 2025, 08:10:28 pm
content: The email they sent at midday, states the problem started on Tuesday evening.David

author: 1980s_john
author_rank: Contributor
timestamp: September 12, 2025, 07:15:49 am
content: CPC / Farnell websites are back this morning, phew!Regards,John

author: NE666
author_rank: Frequent Contributor
timestamp: September 12, 2025, 10:28:49 am
content: Are they fully operational?I was putting a basket together with Farnell about two hours ago and noticed a page banner stating that credit card payments were still offline.
Algorithm for controlling the "charge" MOSFET in a LiFePO4 battery BMS? - Page 1
Forum section: electronics / general

author: e100
author_rank: Frequent Contributor
timestamp: September 04, 2025, 07:44:09 am
content: This is in relation to recent reports of a number of cheap 12v LiFePO4 batteries (Wattcycle, Litime etc.) not sharing the discharge load when 2 or more batteries are connected in parallel. Effectively they take turns in providing all the current. I have yet to see a technical explanation as to what is happening. Does any know?The problem appears to be related to the re-enabling of the BMS 'charge' MOSFET once it has been turned off because the battery has reached a 'fully charged' over-voltage condition (as designed). While 'off' there is a diode drop to the battery terminals which prevents the battery from discharging when there is second battery with a similar voltage in parallel, that is, until its voltage has dropped by 0.6v then presumably the first battery starts supplying current and that triggers the first battery to re-enable its charge MOSFET and so the diode drop disappears and presumably the 0.6v imbalance pushes a huge current spike into the second battery tripping the charge over current protection which disables the charge MOSFET and therefore its terminal voltage now has a diode drop and therefore the first battery is now supplying all the current. Does this sound plausible?
ESD coating sprays for surfaces and storage bins - Page 1
Forum section: electronics / general

author: dkonigs
author_rank: Regular Contributor
timestamp: September 02, 2025, 06:13:10 pm
content: Obviously my lab is full of shelves and storage bins, many of which are made of plastic that can quite easily accumulate a static charge. I like to coat these things some of the time, in an effort to mitigate any concern. The problem is finding a good coating spray that'll actually work for coating these surfaces.These are the things I've tried so far:The can on the left is actually great. Its Staticide ESD #2500. It coats everything with no problem, and tends to leave a milky white finish on surfaces after spraying. I've had no issues with it sticking to my container surfaces. There's just one problem... The can is now empty, its an old product, and long since discontinued. I'd love to get more, or something like it, but have no idea where.The can in the middle is ACL Staticide #6500 and its terrible. It goes on like Windex with carbon particles suspended in it, and seems to accomplish nothing as a result. I just end up with a pool of liquid in the container after spraying.The can on the right is MG Chemicals 844AR. Its a little better, and goes on like a splotchy grey paint. But it doesn't always stick that well. Sometimes it seems to work, but lately its been rubbing right off onto my fingers (and/or scratching off easily).Any other sprays worth trying? As I said, I really liked the one on the left, but I can't get it anymore.
TV transmitter and tower tour - Page 1
Forum section: electronics / general

author: sanleontexas
author_rank: Contributor
timestamp: September 01, 2025, 02:02:17 pm
content: Thank you, very interesting. First digital TV transmitter site I've toured, and enjoyed iteven if it is a virtual tour rather than in person.

author: LaserSteve
author_rank: Super Contributor
timestamp: September 03, 2025, 05:55:36 pm
content: Would like to know more about how they do the transmitter combining with low loss and low S21. At both the module level and with the two main outputs.Very much liked the video, thank you.Steve
What are JLCPCB and LCSC turning into? - Page 1
Forum section: electronics / general

author: Chicane
author_rank: Contributor
timestamp: September 03, 2025, 09:14:25 am
content: I was browsing the parts catalog on JLCPCB and LCSC last week and came across some new and amusing products (see the screenshots below). So, I couldn't resist and contacted JLCPCB support to request the footprints and schematic symbols of C48736161 (an umbrella), C48735895 (an air fryer) and C50325343 (a massager) for my new 12-layer PCB with SMT. Support answered "let me check" and disappeared for 20 min. I didn't have more time to wait and closed the chat, but will be curious to see those footprints.
LDO Noise figure - Page 1
Forum section: electronics / general

author: Sleep Deprived Tommy
author_rank: Newbie
timestamp: August 29, 2025, 04:30:09 am
content: I was checking the Analog Devices portfolio of linear regulators the other day, and as i went through i noticed the ones with the lowest noise figures and the best PSRR and overall the best ones in terms of noise were like rated for 1.2 A (ADP7156) and another series (ADP176x) with the lowest current rating of 1A, i know they've got like 40mA LDOs, why is that the noise figure of the ones with higher current are better than the ones with lower current? that contradicts the statement Shahriar made on the video "TSP #122 - Teardown, Repair & Upgrade of an Agilent 3458A 8.5 Digit Digital Multimeter (April 2018)" at 24:02, what is it that I'm missing out ? can someone please clarify? thanks in advance

author: DimitriP
author_rank: Super Contributor
timestamp: August 29, 2025, 06:08:19 pm
content: Shariar replaced "high" voltage regulators, 3pin 15V and he is not wrong.Then there are newer designs, (well...newer than the 3in of LM317, 7815 family),and out of all the LDOs, some are "low noise" and some are "ultra low noise". Some are "just" LDOs with no remarkable noise performance and they are not $9 a popThat's the general idea.

author: Zero999
author_rank: Super Contributor
timestamp: August 29, 2025, 09:23:53 pm
content: I suspect higher current regulators are lower noise is because, as transistors get larger they generally become less noisy. It's similar to how connecting amplifiers in parallel can improve noise performance.https://www.analog.com/en/resources/technical-articles/paralleling-amplifiers-improves-signal-to-noise-performance.html
IC SCL5419AE Datasheet??? - Page 1
Forum section: electronics / general

author: jcrubin
author_rank: Frequent Contributor
timestamp: July 11, 2017, 01:45:32 am
content: The IC in Question SCL5419AE was found in VDO analogue clocks commonly used in Porsche and VW automobiles during the 1970's. I can find no datasheet anywhere online with regard to this IC, does anyone have info on this chip?

author: Paul Moir
author_rank: Frequent Contributor
timestamp: July 11, 2017, 05:29:11 am
content: Possibly the military spec / extended temperature version of the 7419 TTL chip? Is it in a ceramic package?EDIT: if it ever existed! I can't find it even in way back in the '72 Fairchild databook...

author: Unknown
author_rank: Unknown
timestamp: July 11, 2017, 08:34:29 am
content: It's described in a couple of databooks e.g.1979 icMasteras a "Oscillator/2^23 Divider" or "23 Stage Divider W/Digital Tuning". Probably ran on a standard 4.194304MHz crystal to drive a bipolar clock motor.With an original to reverse-engineer it wouldn't be too hard to rig up a substitute/replacement circuit.

author: jcrubin
author_rank: Frequent Contributor
timestamp: July 11, 2017, 12:08:01 pm
content: Here is a photo of the circuitThe crystal is 4194,812 khzquick breakdownThe back has pin 1 to groundpins 2 to 7 floatingpin 14 looks like +dc and to 100uf cap Apin 13 goes to ground and one side of coil through 100uf cap Bpin 12 unusedpin 11 to other side of coil directpin 10 to crystalpin 9 to crystalpin 8 unusedthe 12v from the battery goes through a voltage dropping resistor to product 10v at pin 14

author: Benta
author_rank: Super Contributor
timestamp: July 11, 2017, 12:39:28 pm
content: It's a device from Solid State Scientific.Back in the 70s/80s they offered a series of metal-gate CMOS ICs to supplement the standard 4000 parts with some special functions.The 2^23 divider is very likely.

author: jcrubin
author_rank: Frequent Contributor
timestamp: July 11, 2017, 06:42:13 pm
content: My neighbor, owner of this clock, and all around intelligent guy, did some investigating and found the following material.IC SAJ300R seems to be an identical IC to the aforementioned

author: Benta
author_rank: Super Contributor
timestamp: July 11, 2017, 07:04:02 pm
content: Quote from: jcrubin on July 11, 2017, 06:42:13 pmThat seems very likely. I found this patent that refers to the SCL5419 in the link to it:https://patentimages.storage.googleapis.com/pdfs/US4199726.pdf

author: tassiesteve
author_rank: Newbie
timestamp: August 27, 2025, 02:43:55 am
content: I just found a very similar board with the same chip in a VDO clock used in a 1970s Datsun Stanza that was likely assembled in Australia and definitely sold here. Thanks everyone in this thread for some information on it.
"You are perfectly safe with rubber shoes...." - Page 1
Forum section: electronics / general

author: paulca
author_rank: Super Contributor
timestamp: August 31, 2025, 10:00:19 am
content: https://youtu.be/JFAAEPnbL58Action labs new video.""Discover why a light bulb can glow under high-voltage power lines. But does this strange effect mean power lines are actually dangerous?""

author: Marco
author_rank: Super Contributor
timestamp: August 31, 2025, 12:01:18 pm
content: You are perfectly safe because you are a bag of water.One of the comments that in the 1960s a power company shielded their house was interesting. This doesn't seem very safe, a shielded house reduces the safety margin for the high voltage cable by quite a bit. That's probably why they started to buy out homes under the cables in my country moreso than health concerns. If people DIY that, it's dangerous.
Robotic Olympics - Page 1
Forum section: electronics / general

author: jonovid
author_rank: Super Contributor
timestamp: August 21, 2025, 08:37:48 pm
content: a truly robotic olympics is now possibleas over 500 robots compete in a three-day event in Beijingas the singularity looms closer to giving robots a brain

author: Bud
author_rank: Super Contributor
timestamp: August 21, 2025, 09:17:53 pm
content: Can't wait for a swimming competition

author: Analog Kid
author_rank: Super Contributor
timestamp: August 21, 2025, 09:29:30 pm
content: Quote from: Bud on August 21, 2025, 09:17:53 pm"Ack ... gurgle ... sputter ... water corroding connections ... must conserve battery power ... must get to dry land ...".

author: tom66
author_rank: Super Contributor
timestamp: August 21, 2025, 10:54:54 pm
content: I wonder what the robot equivalent of doping will be. Charging lithium ion cells to 150% of nominal capacity, just before they burst into flames, so your runner can go just a little faster?

author: themadhippy
author_rank: Super Contributor
timestamp: August 21, 2025, 11:01:14 pm
content: wd40 is listed as a banned performance enhancer

author: Simmed
author_rank: Frequent Contributor
timestamp: August 21, 2025, 11:29:48 pm
content: i like micro mice

author: John Coloccia
author_rank: Super Contributor
timestamp: August 22, 2025, 01:12:54 pm
content: Reminds me of this.

author: RJSV
author_rank: Super Contributor
timestamp: August 24, 2025, 12:52:37 am
content: Haha: Looked like, at the begining, one of the competitors was looking around, to the sides, to gauge its standing, in the group of competitors.(I was always told, to mind my own race speed and position. Don't worry about the competition in nearby lanes. Just go for it.
Need info on Fanuc high speed serial encoders - Page 1
Forum section: electronics / general

author: jmelson
author_rank: Super Contributor
timestamp: August 23, 2025, 05:28:54 pm
content: Hello,I make a line of encoder converter products. I have deciphered the protocol of the Fanuc "serial pulsecoder" that operates at 1.024 Mbit/sec, but am having issues figuring out the high speed version that apparently sends at 2.73 Mbit/sec. I have managed to trigger the encoder to send data by fumbling with a pulse generator, and finally ending up with a 3.3us wide false pulse on the bidirectional data differential pair. If I just provide this pulse, the encoder does not respond. But, by fiddling with the pulse generator's switches, I can get the encoder to start responding with serial data. Does anybody know the protocol to select the modes of the encoder? Anybody ever reverse-engineered these?Thanks very much in advance!Jon

author: langwadt
author_rank: Super Contributor
timestamp: August 23, 2025, 05:51:36 pm
content: https://www.eevblog.com/forum/projects/familiar-with-fanuc-servo-drives-reverse-engineering-serial-encoder/help?

author: jmelson
author_rank: Super Contributor
timestamp: August 23, 2025, 09:38:04 pm
content: Quote from: langwadt on August 23, 2025, 05:51:36 pmYes, I am aware of this thread, but it really doesn't give any more info than I already know (which isn't a whole lot.)But thanks,Jon
ANyone with an idea for Libgen access ? - Page 1
Forum section: electronics / general

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 22, 2025, 12:38:35 pm
content: Libgen.org was a gold mine for information access. Plenty of e-books that are inacessible to mere mortals.Unfortunately, they have to play whack-a-mole with powers that be.Same powers that don't give a shit that Meta hoovered illegal materials trough torrent for their AI on a gargantuan scale, but suddenly they care about mere mortals that need a book.Anyone with an idea how to get to it ?I found various copies like Anie's archive, but that ain't it.IS there a way to mirror it and how much storage would it take ?I've read that content is in bad need of filtering of crap content and deduplication.Has anyone done that ?God damn it, UN should mandate existance of information oasis like this. 🙄

author: thm_w
author_rank: Super Contributor
timestamp: August 22, 2025, 11:22:30 pm
content: You can find some discussion here:https://www.reddit.com/r/libgen/

author: abeyer
author_rank: Frequent Contributor
timestamp: August 23, 2025, 06:53:12 pm
content: also seehttps://annas-archive.li/
Adding some led lights / circuit help - Page 1
Forum section: electronics / general

author: Hornnumb2
author_rank: Regular Contributor
timestamp: August 26, 2025, 02:30:44 am
content: I want to add some led lights to my truck. I would like them to be triggered by a few different sources Cargo light and reverse lights. Would an inline diode control any feedback between sources? Any other things I would need to worry about. Thanks Michael
Need info on Fanuc high speed serial encoders - Page 1
Forum section: electronics / general

author: jmelson
author_rank: Super Contributor
timestamp: August 23, 2025, 05:27:26 pm
content: Hello,I make a line of encoder converter products. I have deciphered the protocol of the Fanuc "serial pulsecoder" that operates at 1.024 Mbit/sec, but am having issues figuring out the high speed version that apparently sends at 2.73 Mbit/sec. I have managed to trigger the encoder to send data by fumbling with a pulse generator, and finally ending up with a 3.3us wide false pulse on the bidirectional data differential pair. If I just provide this pulse, the encoder does not respond. But, by fiddling with the pulse generator's switches, I can get the encoder to start responding with serial data. Does anybody know the protocol to select the modes of the encoder? Anybody ever reverse-engineered these?Thanks very much in advance!Jon
Found objects: DMM - Page 1
Forum section: electronics / general

author: Analog Kid
author_rank: Super Contributor
timestamp: August 16, 2025, 11:09:29 pm
content: Found literally in the dirt, exposed to weather at an abandoned golf course.Took it home, expecting nothing. (Cannibalize a few parts from it?)Just now put 4 AAs in it, turned it on.Goddamnit. It works.Now I have another DMM. (Can't have too many.)

author: armandine2
author_rank: Frequent Contributor
timestamp: August 17, 2025, 03:20:10 pm
content: ---[confounding expectation] I also found something electronic - on Friday I retrieved a discarded oscillating tower fan (with remote), expecting my dismantling of it would only hasten its final demise.But it is still in with a shout, with just a fuse so far found to be faulty. And only 3 Triacs (MAC97A6) and the motors still to test.I was fortunate in dismantling to recover the fuse wire end pieces and press them onto my replacement fuse body without damage. Also fortunate in the construction of a homemade special tool, to remove the fan body (split halves) security screws.

author: armandine2
author_rank: Frequent Contributor
timestamp: August 17, 2025, 07:39:05 pm
content: .. reassembly completed and it worked. The fan, from the mucky state of it, has been in long use. But still quiet and effective.Not sure of all the controls yet.

author: Analog Kid
author_rank: Super Contributor
timestamp: August 17, 2025, 07:43:52 pm
content: I was thinking maybe we could turn this thread into a sticky-ish one where people could post about retrieved/mudlarked objects that ended up working?Just a thought ...

author: armandine2
author_rank: Frequent Contributor
timestamp: August 17, 2025, 08:03:12 pm
content: ...the generality I thought might be in the confounding of expectation....you were surprised it still worked....I was surprised to be a fixya

author: Analog Kid
author_rank: Super Contributor
timestamp: August 17, 2025, 08:20:46 pm
content: I like your homemade "security" screwdriver there.I've made lots of those over the years. Triangle head, split slotted like yours, others.Fun trying to defeat all those "speciality" screw heads.

author: armandine2
author_rank: Frequent Contributor
timestamp: August 17, 2025, 08:54:02 pm
content: ...I'm glad you picked up on that.The "repair", for what it was, was easily made despite the two issues I mentioned.Often repairs go to pot because the thing's complex design confuses the repairer.I avoided the weeds - so to speak - with this one. The found object's capacity for survival might be a common thread.[edited to add a smiley]