hybridfree/eevblog-posts huggingface dataset:
Resources for doing DSP/SDR type stuff? - Page 1
Forum section: electronics / projects

author: MatCat
author_rank: Frequent Contributor
timestamp: January 10, 2014, 08:51:23 pm
content: I am mucking about with my XMOS XCore STARTKIT and want to experiment with doing some SDR/RF stuff using a DAC. I am not really sure where to start to get how to convert analog concepts into mathematical equations, specifically I want to implement QAM but not sure where to look, any ideas would be fantastic!
Resources for test equipment architecture and block diagrams - Page 1
Forum section: electronics / projects

author: MajorEE
author_rank: Contributor
timestamp: January 08, 2021, 10:43:46 pm
content: Are there any good databases or reading material that have block diagrams of test equipment architecture?I love the tear downs that explain block by block of what's going on and can't get enough.Are there any good books you folks recommend that just discuss the high level architectures of test equipment?

author: DaJMasta
author_rank: Super Contributor
timestamp: January 09, 2021, 05:21:01 am
content: If you can get a hold of service or operating manuals for equipment you're interested in, they will often have what you're describing. Operating manuals without a block diagram for the system will usually at least have a description of how it works, as knowing something about the architecture of the instrument is important to understanding its behavior and performance characteristics. So if you have a particular kind of gear or manufacturer in mind, I would look towards their publicly available stuff first. There's always places like KO4BB's repositoryhttp://www.ko4bb.com/getsimple/index.php?id=manuals
Response to ESS question - Page 1
Forum section: electronics / projects

author: Chris Peterson
author_rank: Newbie
timestamp: March 25, 2013, 12:40:16 pm
content: The assumption is that ESS will be run at the manufacturing plant, so it comes in the test schedule before other testing - even if you are the manufacturer. (I teach -810 and this is a common question.) If you have other questions please don't hesitate to ask.
Restoring an IBM Lenovo Think Pad tablet PC  - Page 1
Forum section: electronics / projects

author: Lawsen
author_rank: Frequent Contributor
timestamp: May 10, 2011, 03:16:49 am
content: The IBM Tablet PC came from an E Bay surplus store. The Li ion battery cannot hold an electron charge. The battery pack has to be replaced. The most difficult problem was the operating system was not the correct one, Microsoft Windows XP Service Pack 3. It was compatible to everything, but the stylus pen mouse arrow control. To all IBM Lenovo Think Pad and Think centre, there is a company in Atlanta, Georgia that sells aftermarket restoration discs to restore the Think Pad and desk top Think Centre like new. The discs come in 7 to 9 discs and the computer must boot, start on the IBM Lenovo restoration store 7 discs. I did not know how to use those restoration discs, until later. There were no instructions on how to use those discs. I have experience to work on one and the second one will be easy.Lawsen

author: saturation
author_rank: Super Contributor
timestamp: May 10, 2011, 12:35:49 pm
content: New netbooks are being dumped because of the fury for iPads and Android clones. You can get either an Android pad or netbook with 8+hour battery life for $200; is it worth repairing the Lenovo?

author: PeterG
author_rank: Frequent Contributor
timestamp: May 14, 2011, 02:19:22 am
content: I am waiting for someone to release a 10" Tablet that i can install my own OS of choice on. As it is now, your stuck with whatever is on it when you buy it.Ultimately i would like to have a tablet running linux or any other os thats not "MS Made".Regards
RESTORING OLD 1982 ELEKTOR PRECISION POWER SUPPLY PROJECT 82178 - Page 1
Forum section: electronics / projects

author: hbt
author_rank: Contributor
timestamp: April 22, 2018, 02:00:36 am
content: Hello all.I've came up with a power supply I built while in high school with a schematic of a 1982 Elektor magazine.On the process of trying to restore it and studying back the schematic to try to make some sense out of it, as far as I'm capable of, I came up with a question that couldn't find an answer to.On the schematic and parts list for the power supply, the article mentions two 100uA meters to measure voltage and current. My problem lies on the fact of not understanding what the 100uA means regarding the choice of meters. Does it means I need to choose two ammeters with a 100uA range and then change the printed scale or is it some specification of the analogue meters which I can't identify on any meter I've come up with?Also, if, in order to upgrade the power supply, I'd like to get one digital LCD voltmeter and one digital LCD ammeter, how should I connect them to this schematic?I'm assuming the specific ports on this PCB to the meters specified on the schematic, are designed or placed in order to measure a very low current , which translates to the scale of the meter. I don't quite get how the digital meters should be implemented here. Or is it just a paralel connection on the power supply output for the voltmeter and a serial connection for the ammeter?In the future, If I'm able to get this one back to work, I may consider building another one so I can connect them in series to have symmetrical voltage to power some projects in need of it.Attached you can find the schematic for the power supply in question.Any help would be extremelly appreciated.Thank you in advance.

author: wolfp
author_rank: Contributor
timestamp: April 22, 2018, 06:31:13 am
content: Hello hbt,welcome to the world of old power supplies. Your circuit drawing shows a standard layout around an 723.The two meters are really 100uA-meters (short estimation: 30V, 100uA means 330kOhm) and it is easy to replace them by digital instruments.For the voltage you can connect a digital voltage meter to the output. Because of the high input resistance it will not significantly influence the current measurement.For the current it could make sense to consider the voltage drop of the digital ammeter or measure the voltage across the 0.22Ohm resistor (try to calculate the voltage across this resistor at 1A and at maximum current).It could also make sense to exchange the elkos against new ones.
Resurrecting Universal Programmers and Testers Hi-Lo Systems All-03 and All-07 - Page 1
Forum section: electronics / projects

author: Paradroid
author_rank: Contributor
timestamp: June 27, 2025, 04:20:23 am
content: Hi,I have set up a FreeDos machine to make use of these old universal programmers. I found lots of valuable information on Matthieu Benoit's pages, including schematics. Even found low-level programming information for the All-03 (aka Expro-60) using the Wayback machine, as the Danish website that hosted it is down. This got me even more interested in these units, as I could write up some code to test retro-chips like the C64 CIA chips 6526/8521 or even a CPU. Let me know if you're interested in that info - I've collected it in a libre office document, so I can export a PDF.The All-03 uses an ISA card, and a machine with such a slot is hard to find. The All-07 uses the LPT port and shares lots of similarities in the schematics, but I have not been able to find a clear-text description of it's low-level programming. If anyone has that, please let me know. I would not like to dive deep into the schematics and GAL sources (which were published by EEVBlog forum user @tinhead - thanks!), but ideally build on existing sources.I see that there's some community software available for the All-03, but again, finding an ISA machine is a long shot in 2025. However, it would be great if some people who also own this early-1990s gear who are more software-oriented than I am would gather in this thread. I've been in contact with Matthieu Benoit via eMail, but I feel that with the huge success that these programmers/testers were on the world market, there should be more people who have this type of programmer - possibly still in use for the same reason that I am resurrecting these from catching dust.

author: Paradroid
author_rank: Contributor
timestamp: July 01, 2025, 05:06:00 pm
content: I worked a bit on gathering programming information about the All-03, Expro-60 and Modular Circuit MOD-EMUP. First public version attached, but there's either an error in the available schematics, or the Equation file of the U5 GAL is wrong. I have addressed that in the document, will continue to look for correct information. Comments more than welcome.Jens

author: BennoG
author_rank: Frequent Contributor
timestamp: July 02, 2025, 05:53:58 pm
content: I have a ALL-07 somewhere laying around.Would be nice if I can use this again for chip testing.Benno
Retrieve waveform through GPIB on TDS744A: Does the command exist? - Page 1
Forum section: electronics / projects

author: mlefe
author_rank: Regular Contributor
timestamp: January 20, 2018, 03:43:22 am
content: I've been playing with Arduino to communicate with a Tektronix TDS744A (Thanks to Emanuel Girlando's work:http://egirland.blogspot.com.co/2014/03/arduino-uno-as-usb-to-gpib-controller.html)I wrote a VBNET app to send and receive commands and, after fighting a lot, I've been able to retrieve a hardcopy of the screen as a BMPBut I'm still struggling to find the GPIB command that allows me to retrieve the raw data points of the waveform: do you know if that's even possible?Thanks!

author: mlefe
author_rank: Regular Contributor
timestamp: January 20, 2018, 03:48:06 am
content: I'm sorry for the post, as soon as I finished writing it, I found the right documentation to do it...In case you're wondering, it's called "CURVe".
Geolocation of an IOT project - Page 1
Forum section: electronics / projects

author: csheldon
author_rank: Contributor
timestamp: October 29, 2017, 05:51:45 pm
content: Hello,Does anyone possibly know what is the best way of getting fixed geolocations of some IOT project.I would not like to use GPS modul. Because it's counter-intuitive. It's a constant fixed location and i needed it to be precise within cca 5 meters.What method are applicable.I am aware of google API for geolocation which looks for a few access point based on which it gets the position. But that's to unreliable. I need this to not depend on wifi signals excepts on it's own wifiAny help is greatly appreciated

author: Marco
author_rank: Super Contributor
timestamp: October 30, 2017, 12:26:18 pm
content: Unless you can put up your own RF beacons, gps, wifi and cell id are the options. With only GPS getting the required accuracy.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 30, 2017, 12:33:43 pm
content: Quote from: csheldon on October 29, 2017, 05:51:45 pmIf it is constant and fixed... then can't you survey it and then configure it?You need to be more specific as to your requirements. Also, the US government spends billions of dollars to achieve positional accuracy and for the trivial cost of GPS receiver module you can leverage their investment. (If you have line of sight to the sky etc etc)... what makes you not want to utilise GPS?

author: csheldon
author_rank: Contributor
timestamp: October 30, 2017, 06:54:13 pm
content: what do you mean by surveying and configuring?I think that it is redundant to have a GPS reciever for a fixed location that doesn't change and needs only one-time setup, don't you think?

author: Rerouter
author_rank: Super Contributor
timestamp: October 30, 2017, 07:20:46 pm
content: Use a phone app to activate the thing, tell the user to be within 5m of it, then scrape the gps position of the phone.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 31, 2017, 11:21:14 am
content: Quote from: csheldon on October 30, 2017, 06:54:13 pmYou place it... work out where it is (using a GPS, compass, sextant etc) and configure it to know where it is.

author: sokoloff
author_rank: Super Contributor
timestamp: October 31, 2017, 12:40:19 pm
content: Quote from: csheldon on October 30, 2017, 06:54:13 pmYou don't need to leave the GPS receiver with the IoT device nor build it into it. You need an IoT device, a GPS receiver at the site, and a means to get the GPS location data from the GPS device into the IoT device.

author: csheldon
author_rank: Contributor
timestamp: November 01, 2017, 10:26:37 am
content: Quote from: sokoloff on October 31, 2017, 12:40:19 pmYes, that is the best solution I think. Now...how can you do that to avoid programming at the site?

author: Ian.M
author_rank: Super Contributor
timestamp: November 01, 2017, 10:40:43 am
content: You've got an IoT device which means it can be accessed over the Internet. Put a unique QR code on it and write an Android app that updates the device specified by the QR code with the GPS location of the phone or tablet at the moment it scanned the QR code.
retro 1940 guitar amp build  - Page 1
Forum section: electronics / projects

author: valvedude
author_rank: Contributor
timestamp: October 11, 2014, 10:02:37 pm
content: here is the other amp i just finished it took 6 months to build from scratch a lot of fun any thing is possible all you have to do is have a goi am self tough and all my skills come from reading learning books and reading forms and talking to peoplei thought well most amp a box's why not brake the mould do some the comply different etcand the sound and tome was amazing and the level of volume incrediblehttps://www.flickr.com/photos/127793137@N02/all the timber came from my tv unit i could not give it away so i cut it upthe same timber went into making the 2nd amp

author: valvedude
author_rank: Contributor
timestamp: October 11, 2014, 10:42:18 pm
content: the electronics constructionhttps://www.flickr.com/photos/127793137@N02/

author: Vgkid
author_rank: Super Contributor
timestamp: October 12, 2014, 01:39:58 am
content: Nice job on the speaker enclosure.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 12, 2014, 02:45:37 am
content: Great cat!

author: valvedude
author_rank: Contributor
timestamp: October 12, 2014, 06:00:08 am
content: Quote from: vk6zgo on October 12, 2014, 02:45:37 amthanks that's missy cat

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 12, 2014, 02:38:17 pm
content: I like the green hammertone enclosure. Is that the correct term? Anyways it's very original looking.

author: valvedude
author_rank: Contributor
timestamp: October 13, 2014, 08:48:34 pm
content: yep good paint finish i think too
Retro CRT monitors - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: March 27, 2020, 09:58:54 pm
content: Good evening (o;Someone knows a source where I could get unused or barely used old CRT screens with screen sizes below 12" ?For example like in size of the Apple IIc green monitor....could also be amber....Intention is to do some retro project with modern FPGAs (o;thanks in advancerichard
Retro GPS Speedometer from #722 - Page 1
Forum section: electronics / projects

author: mrstevenund
author_rank: Newbie
timestamp: November 19, 2015, 07:19:16 pm
content: Has anyone found any info on the Retro GPS Speedometer sent in to blog #722 mailbag?I found the PDF from the box -http://www.adventcontrols.co.uk/103Published.pdfand a page for it -http://adventcontrols.co.uk/bttf.htmthe page says seewww.firmtec.co.ukfor details, drawings, and gerber files, but I don't see any of that.Has anyone else found anything?
Retrobrite (Retrobright) Question - Page 1
Forum section: electronics / projects

author: rfdes
author_rank: Regular Contributor
timestamp: December 26, 2021, 11:12:56 pm
content: I am anxious in hearing from anyone who has had good/bad experiences using the retrobrite process. My main interest is in any damage incurred to decals attached to the ABS plastic. I see videos of many keyboards+keys (with letter/number decals) which successfully survived the hydrogen peroxide/heat/UV treatment. I have a piece of test equipment that has similar front panel decals and would like to treat the plastic to this process but am a bit concerned. I have been unsuccessful in finding anyone that claims the process has damaged decals on their treated ABS plastic.Your opinions and advise are welcome.Jim
Return Loss of SMD Resistors - Page 1
Forum section: electronics / projects

author: ocw
author_rank: Regular Contributor
timestamp: May 31, 2017, 03:34:35 am
content: After stumbling into an old article in Electronic Design (seehttp://defenseelectronicsmag.com/site-files/defenseelectronicsmag.com/files/archive/rfdesign.com/mag/511RFDF3.pdf) I decided to complete a similar evaluation of the SMD resistors which I already have in stock. I measured the resistor's return loss and its series resistance and reactance from 5 kHz - 900 MHz. Stray reactance in my test procedure invalidates readings above that frequency using my Array Solutions AIM-UHF impedance analyzer.For a simple beginning I thought that I would start with my 1k resistors. Most axial resistors with values of around 200 ohms and under have reactance which don't significantly affect its impedance up to the mid-VHF frequencies. It becomes hard to find axial resistors with values of 10k and above which aren't seriously limited by their reactance.The Panasonic ERJ-6ENF1001V resistors were the clear winners in the 2012 size SMD category. The Arcol/Ohmite APC0603B1K00N were significantly better than my economy Yageo 1608 resistors. I threw in some axial resistors for comparison. They came out better than I expected. The IRC/TT CMF1/41001FLFTR resistors were the best of those available. Other brand/model axial resistors of different values which I have had significantly worse performance.I'm not sure who made the EF Johnson numbered resistors which I included in the tests.I have many other brand and model SMD resistors in other values which I didn't include. I skipped the 988 and 1,010 ohm resistors which I also have as well as many more additional values.For reference I also included my evaluations of two of the RF resistors which I have. I included the Vishay 50 ohm FC0603E50R0BTBST1 20 GHz 0.1% and 221 ohm FC0805E2210DTWS 20 GHz 0.5% resistors. Check out the attachments below.
Return Path for Bipolar Signals (EMC) - Page 1
Forum section: electronics / projects

author: dannybeckett
author_rank: Contributor
timestamp: April 05, 2022, 02:46:06 pm
content: Hello,I found an excellent guide on how to set your layers for good EMC performance:Can't recommend giving this a watch more. However, there is one case that isn't really covered. How should you route bipolar signals on a 4 layer board? If my 4 layer stackup goes....+12v/siggnd1mm FR4 core-12v/siggnd....do I end up in a situation where a bipolar signal trace on L1 cannot couple to its desired reference plane (L4) when in the negative direction and field spread occurs? Or will L2 act as a "surrogate" reference plane for -12V when called upon (even though we don't have access to the beneficial inter-plane capacitance between L3 and L4 for for -ve rail power delivery)?
Reusing a 2560x1440 Touchscreen Display With Two eDP Connectors - Page 1
Forum section: electronics / projects

author: randomperson
author_rank: Newbie
timestamp: June 27, 2024, 02:27:31 pm
content: Hi, I'm not sure if this is the right forum for my question, but here goes...Someone recently gave me a touchscreen OLED display (model number: Samsung ATNA40JU01_MFPC Rev 1.0), probably from a Lenovo ThinkPad X1 Yoga, but I don't have the original laptop, so I don't know exactly which laptop it's from. I wanted to see if I could get an adapter to use it as an external display, but there appear to be two 40-pin eDP connectors on it (see attached images). According tohttps://hackaday.io/project/179868-all-about-laptop-display-reuse/log/209701-common-edp-laptop-panel-pinouts, 40-pin connectors can meaneithera higher resolution than 1080porat most 1080p+touch (although I did see other displays that appear to have a higher resolution+touch, but only a single connection - is that maybe possible in newer versions of the eDP protocol?).My theory was that this particular display is split into two parts that are each controlled by a regular eDP connection with touch (two eDP lanes+touch, as shown in the Hackaday article). I really don't have any experience with this, though, so I wanted to ask if anyone else here knows more. I tried to search online for this display and generally displays with two connectors, but I couldn't find any more useful information.One more note: I don't reallyneedthis display, I have plenty of other laptop displays I could use if I needed them. I really just want to figure out what's going on because I'm too invested now...Thanks in advance for any help!
Reusing BGAs from prototypes? - Page 1
Forum section: electronics / projects

author: stmdude
author_rank: Frequent Contributor
timestamp: October 28, 2018, 05:40:17 pm
content: I've started amassing a few prototype boards (of my own) with CPU+DDR3 chips on them. Just over $20 in components right there, never to be used again. Or?Would I be shooting myself in the foot (yield-wise) by removing them, cleaning, reballing and re-using ?Just to be clear, since "reballing" is a dirty word on this forum. I'm _not_ trying to repair any chips. The chips and boards work fine. I just want to re-use the chips on a newer revision of the PCBs.

author: brabus
author_rank: Frequent Contributor
timestamp: October 28, 2018, 06:49:53 pm
content: Nothing bad on the technical side of things, if we are talking about a prototype.It all depends on how much you do value your time. If you work at, e.g. 100$/hour and it takes two hours to remove the BGAs and reball them, you just spent 200$.If the chips are worth more than that (or if your time is worth less), go for it.

author: james_s
author_rank: Super Contributor
timestamp: October 30, 2018, 02:32:19 am
content: It can be good practice, it all depends on your goals, how much time you have, how much value you place on your time and how much you enjoy doing this sort of work. Personally I wouldn't hesitate to reuse the parts if I had a good use for them.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 30, 2018, 03:43:34 am
content: Yes, good for practising, but extremely time-consuming.As said above - mostly depends on how much you value your own time.

author: mrpackethead
author_rank: Super Contributor
timestamp: October 30, 2018, 04:02:19 am
content: Oven with a spring lift. Quite a resonable process. Personally i perfer doign it in the vapour phase. But it does mean another heating cycle.

author: stmdude
author_rank: Frequent Contributor
timestamp: October 30, 2018, 06:57:19 am
content: Thanks guys!Since I do this for fun, I don't really value my time as long as I'm learning something.Seems like I'm investing in a few new toys! (Vice, stencils, solder-balls, etc)

author: station240
author_rank: Unknown
timestamp: October 30, 2018, 06:16:30 pm
content: If you've not seen this video yet, on why it's better to use dry paste of reballing BGA, you need to.
Reusing camera from N70 - Page 1
Forum section: electronics / projects

author: ResR
author_rank: Regular Contributor
timestamp: January 11, 2014, 06:14:53 pm
content: I'm planning to reuse an old N70 cellphone (it had it's main processor gone dead - moisture to be blamed) rear camera module (14-pin 2 row gold-plated pad configuration) for my robot project. Somehow I got my eyes on the schematic meant for "authorized nokia service centers only". I found the camera in the schematic. Can I use regular pic-type microcontroller instead of OMAP to feed data through RFM73 to control center with TV? Is it cheaper-to-purchase/easier-to-implement actual camera module (CLVMPC2 - 37,60€) with 1 Vp-p composite (75 ?) output for this purpose?
Reverse / Analyze fender Bassman attenuator circuit  - Page 1
Forum section: electronics / projects

author: mkiijam
author_rank: Regular Contributor
timestamp: March 10, 2024, 05:47:02 pm
content: This was/is used with a Fender Bassman. I'm supposed to make sure it's working right. it's not labeled as to which jack is which. If jack 1 is the connection to the amp, then at full CCW it seems there would be an issue with the short?

author: dobsonr741
author_rank: Frequent Contributor
timestamp: March 10, 2024, 07:48:21 pm
content: Jack 2 is to the amp. The pot's arm is the output - to jack 1. IMO, it's a lot of waste of power using this, and a risk of loading the amp with less than 4 ohm. However, it might serve a purpose. As told here. Long live the loud!
Reverse bias protection with p-Mosfet for 4xAA cells - Page 1
Forum section: electronics / projects

author: alexg
author_rank: Regular Contributor
timestamp: December 20, 2018, 05:11:17 pm
content: Hi all, due to out of stock on part I am currently using, this one:https://www.onsemi.com/pub/Collateral/FR014H5JZ-D.pdf, I need to replace it with p-Mosfet, I am trying to choose the right candidates, can you please take a look into these few and let me know if you see any issues?Project parameters:Power supply - 4xAA cells in series, so only rev. bias protection necessary if from user error.With fully charged batteries max reverse votlage is -7VWith almost discharged batteries min rev voltage is -3.6VCurrent consumption is well under 100mAOnly peak current consumption is during startup when caps are discharges (bulk cap and voltage regulators) but I suppose that will Be limited by AAs internal resistance ,etc, so about 2A peak only during startup.So if I understand correctly I need to find p-mosfet that meets following criteria:1. Vds +-7V or more3. Rds 50mOhm or less to be sure there is no voltage drop in the system3. Vgs (-3.6-0.6=-3V) or less, to be able to turn on with almost depleted AA batteries4. Vgs max be at least 7VI am thinking about these 4 specimens, what you think?http://www.ti.com/lit/ds/symlink/csd25310q2.pdfhttps://www.fairchildsemi.com/datasheets/FD/FDMA520PZ.pdfhttps://toshiba.semicon-storage.com/info/docget.jsp?did=481&prodName=SSM3J130TUhttp://www.vishay.com/docs/72024/72024.pdfThank you in advance.

author: ignilux
author_rank: Unknown
timestamp: December 20, 2018, 09:00:06 pm
content: Any of those should work. I'd go with the lowest Rds,on specified at the Vgs you'll be in. Looks like the TI wins there. Furthermore, traditionally N-channel mosfets have lower Rds,on vs P-channel mosfets. There are a lot more to choose from, too. In a battery-powered application like this you can simply place it in the return path to the negative terminal, and connect the gate to the positive terminal.Edited for lack of reading, carry on.

author: ignilux
author_rank: Unknown
timestamp: December 20, 2018, 09:06:32 pm
content: Haha yes, I edited my comment before I saw your response.

author: TimNJ
author_rank: Super Contributor
timestamp: December 20, 2018, 10:06:02 pm
content: I would recommend using an N-channel MOSFET. It's no harder than using a P-channel. Connect the source to your circuit's local "ground", and drain to the negative terminal of the battery holder.Pick the lowest RDS(ON) FET you can get.Interestingly, in a switching application, operating in kHz or MHz region, the lowest RDS(ON) FET is not always preferred because low RDS(ON) FETs also have high gate charge and input/output capacitance. When you switch a device on and off thousands or millions times a second, each switching event has its associated switching loss (due to Qg or Ciss/Coss).But, here, there is no switching loss, because once it's on..it's on! So gate charge/capacitance isn't really a problem.
Reverse breakdown of BE junction: damaging current? - Page 1
Forum section: electronics / projects

author: dom0
author_rank: Super Contributor
timestamp: July 22, 2015, 09:32:19 am
content: So ... the reverse breakdown of the BE junction of BJTs is well-known. What doesn't seem to be well-known is how high the breakdown current must be to permanently degrade the part. I read some vague references like "Beta is permanently lowered at low reverse currents" and the like, but nothing solid. Does that mean µA? A few hundred nA? So, what's the maximum reasonable reverse ib for your average few-hundred mA ic, couple-dozen V Uces low power transistor like a 2N2222 or a BC337?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 22, 2015, 10:04:00 am
content: Depends on the extent of damage. I've never seen data on how fast the damage accumulates (presumably, it's a dosage measured linearly by charge), and to what currents it causes problems at (presumably, higher doses cause a higher current threshold effect?); you'd have to run trials yourself to see.Also interesting to see, would be the effect on low frequency noise (0.1-1000Hz?).Supposedly, it can also be partially annealed at soldering temperatures.Maximum safe level? Vebo is measured at 10uA, but beyond that, Idunno. To what end? If you want a good zener, get a real one; much less noise, and guaranteed voltage level. If for repetitive conditions in an amplifier or switching circuit, use an antiparallel (E-B) protection diode (or a lower voltage bidirectional TVS, or a series prevention diode).Tim

author: dom0
author_rank: Super Contributor
timestamp: July 22, 2015, 10:22:56 am
content: Thanks for the answer. It still does surprise me that no one ever collected this data, but then again countermeasures are usually simple or not needed at all by design.

author: nqtronix
author_rank: Newbie
timestamp: July 22, 2015, 04:01:47 pm
content: I've used the BE breakdown of the BC807/817 to protect the gate of (slow switching) mosfets a few times. They break down relative precisly at 8V, which is good enough for me. Considering a typical zener diode withstands several mA witout issues I decided to go up to 1mA BE reverse current. Till now it works fine. If you don't care about the accuracy of the breakdown voltage, band just need a relativly current independed voltage drop like the 0.7V pn diode drop then go for it, else get a zener diode.

author: edavid
author_rank: Super Contributor
timestamp: July 22, 2015, 04:41:09 pm
content: Quote from: dom0 on July 22, 2015, 09:32:19 amZero tolerance!(I just don't see any reason why there would be a threshold.)See also:https://www.eevblog.com/forum/projects/bjt-ce-breakdown-permanent-degradation/msg633836/#msg633836and later posts in that thread
Reverse current protection for power supply - Page 1
Forum section: electronics / projects

author: hlavac
author_rank: Frequent Contributor
timestamp: May 22, 2014, 09:20:54 am
content: I want to use a cheap 12V/20A LED power supply to power my 3D printer.I suspect it has no protection for reverse current (back EMI from motors) as it is made for LEDs that will never force reverse current back into power supply.I need a protection circuit that will stop the voltage/current that gets induced when someone moves the motors by hand quickly from destorying the power supply...I was thinking about putting a 13V zener across the output but that looks a bit flimsy... biggest power zener I can find atm is 5W rated. Higher power zeners are ridiculously expensive...Anyone got a good circuit that will- short out at 13V thru something beefy that can take ~50W of power- release once the voltage drops back to 12V so that the power supply is not shorted out- will not oscillate (much)?

author: hlavac
author_rank: Frequent Contributor
timestamp: May 22, 2014, 10:14:38 am
content: Maybe something like this?

author: george graves
author_rank: Super Contributor
timestamp: May 22, 2014, 10:17:15 am
content: I use one of those on my 3d printer. So do lots of people, without issue. Just FYI.
reverse engineer LED dimmer/flasher ? - Page 1
Forum section: electronics / projects

author: jmelson
author_rank: Super Contributor
timestamp: March 14, 2020, 07:09:16 pm
content: Has anybody reverse-engineered the 3-button flasher/dimmer module that is sold with LED strips? It has an Atmel 24C02 EEPROM (2 KB) and an SOIC chip with no label. But, with an EEPROM on there, it seems it has to be some common microcontroller. Then, there are 3 paralleled Si2302DS MOSFETs to power the LEDs.I've attached photos of the module as supplied, and with the heat shrink cover removed, fromt and back.Thanks for any info anyone can provide.Jon

author: TomS_
author_rank: Frequent Contributor
timestamp: March 21, 2020, 12:38:39 am
content: At a guess, the EEPROM may hold data used to adjust the brightness of the LEDs at some point in a display pattern. That way the micro can simply increment a counter, read a couple of bytes from the EEPROM at an address that corresponds with that counter value, and apply those bytes to various timers to turn the LEDs on/off to produce the required PWM, patterns etc.I cant immediately think of any other reason to include something like that in something so cheap.That also means you can use any manner of bargain basement microcontroller with minimal features, even if you have to bit bang some SPI or I2C to read the EEPROM.If you have the tools, start with a dump of the EEPROM and see what it contains.

author: james_s
author_rank: Super Contributor
timestamp: March 21, 2020, 01:03:56 am
content: My guess is it's a very cheap microcontroller with an external EEPROM to hold the patterns. The hardware itself sounds pretty trivial, probably not much to reverse engineer. All the "magic" is going to be in the firmware but I doubt there's anything spectacular going on there either. Probably one of those cases where they found the cheapest possible way to build a whole bunch of these things.
Reverse Engineer or Datasheet Available? - Page 1
Forum section: electronics / projects

author: domremy
author_rank: Newbie
timestamp: March 09, 2019, 12:22:53 pm
content: Hello,I need the data sheet for component PXE1610 which is manufactured by Ifineon. It seems almost impossible find so I wonder if anyone can reverse engineer this chip or if anyone can provide me with the datasheet?Thanks!

author: Rerouter
author_rank: Super Contributor
timestamp: March 09, 2019, 12:33:44 pm
content: Have you tried emailing Infineon, If the info is not public it may be behind NDA for stupid reasons,If its something you want to build into a product, drop it, if its something your trying to repair, try emailing them first, or searching for the series name

author: RES
author_rank: Regular Contributor
timestamp: March 09, 2019, 01:22:17 pm
content: FP1008L1-R150-ROEM Design: PXE1610Description: Asynchronous Step-Down Converter,CPU Power for VR13 6+1 phases

author: domremy
author_rank: Newbie
timestamp: March 09, 2019, 03:10:46 pm
content: Thank you for your replies.Yes, I have tried to contact Infeon but it is behind NDA and it is a piece of equipment I want to repair.Quote from: RES on March 09, 2019, 01:22:17 pmI am sorry for such a poor question but do you mean the datasheet for FP1008L1-R150-R will be the same for the Infineon chip? Is it the same chip?Thank you for your help

author: tsman
author_rank: Frequent Contributor
timestamp: March 09, 2019, 05:11:39 pm
content: If you want this reverse engineered then you're going to have to do it yourself. That series of chips was originally by a company called Primarion and there are some datasheets for other devices lurking around . There may be some equivalent Infineon branded versions as well. Look to see if there is anything in common which will help you.Quote from: domremy on March 09, 2019, 03:10:46 pmFP1008L1-R150-R is a SMD inductor so I've no idea what that post is trying to say.

author: domremy
author_rank: Newbie
timestamp: March 10, 2019, 10:40:59 am
content: Hello,Thank you for your reply. I don't know how to reverse engineer unfortunately.if someone could help me find the datasheet for the PXE1610 or help me reverse engineer I would be happy to make a donation to the site.

author: JoeO
author_rank: Frequent Contributor
timestamp: March 10, 2019, 02:19:16 pm
content: What is the piece of equipment you are trying to repair?Maybe the schematic of the unit is on the web.

author: domremy
author_rank: Newbie
timestamp: March 19, 2019, 05:49:25 pm
content: This motherboardSUPER MICRO SUPERO C7Z270-CGhttp://www.hwbattle.com/bbs/board.php?bo_table=cpumbram&wr_id=34250&ckattempt=1There are photos of the PXE1610 0BDN further down the page
Reverse engineering a battery pack controller - Page 1
Forum section: electronics / projects

author: elliot
author_rank: Newbie
timestamp: September 04, 2015, 08:15:31 pm
content: Hi everyone,I have been attempting to reverse engineer the CII-ME370T ASUS battery pack controller.To do this I have produced a schematic of the board:I have been unable to identify any of the chips, though it is obvious that U1 is the"fuel gauge" chip with temperature sense etc, U3 and U4 are some sort of switch and U2 isan under voltage protection device.I have read the internal registers with I2C:address:0x55Register contents: (32 registers, multiple reads)0 19 to 1D1 602 003 004 FF5 FF6 9F to E87 0B8 6E to 709 0C10 06 or 8611 0112 0013 0014 4215 1016 0017 0018 4219 1020 0021 0022 FF23 FF24 FF25 FF26 F627 FF28 0029 0030 0C31 FEI could probably work out the functioning of U1 by exhaustively attempting to write tothe internal registers but it would be very much appreciated if anyone could give me aclue as to identity of U1.Cheers, Elliot.

author: nctnico
author_rank: Super Contributor
timestamp: September 04, 2015, 09:13:16 pm
content: A BQ27541 from TI? TI is about the market leader in battery management systems.

author: elliot
author_rank: Newbie
timestamp: September 04, 2015, 09:37:05 pm
content: Thank you nctnico,I thought I had checked out all the TI parts but I must have missed the bq27541cheers, elliot.

author: eas
author_rank: Frequent Contributor
timestamp: September 04, 2015, 10:07:26 pm
content: In case it is of interest, my crummy arduino code for reading out and interpreting the register contents:http://powercartel.com/projects/packprobe/documentation/.Also includes some links to docs on the smart battery standard.

author: amyk
author_rank: Super Contributor
timestamp: September 05, 2015, 02:48:04 am
content: U2 is likely one of the standard 5-pin single-cell protection ICs like Ricoh R5400N and Seiko S-8211x, U3/U4 are dual N-MOSFETs.
Reverse engineering a black box circuit? - Page 1
Forum section: electronics / projects

author: Andrew_K
author_rank: Contributor
timestamp: June 25, 2022, 06:25:07 pm
content: Hi All,I'm looking for advice or resources (textbooks, articles, programs, etc) on how to characterize and reverse engineer a "black box" circuit.Not just get measured parameters, but actually get a transfer function (and equations, so poles and zeros), and come up with an actual schematic.----In my particular case, I am trying to create a schematic from a semi "black box" circuit. I do have a few known values and a rough skeleton of what the circuit is.The circuit is a filter of some kind. I believe it is a 2-cascaded RC low pass. The resistor values are known.There are two metal disks that are connected to the 2 inner nodes of the resistors. There is a plastic shell and spacer that (I assume) are to form capacitors.As for things I've tried:1) I tried taking it apart and measuring in parts.I removed the middle wire and measured the capacitance between the metal disks, as well as each metal disk to shell.Using the 3 measured values and their respective parallel/series combinations, I solved for the 3 capacitors individually.This actually gave me a negative capacitance between the two disks.2) I tried using a network analyzer to get 2-port S parameters. I used these to calculate the Z-parameters, as well as the voltage transfer function.This plot shows the log sweep and lin sweep (magnitude)Note that this circuit was *NOT* at 50 ohm characteristic freq. However, the impedance values calculated seemed (mostly) reasonable. The VNA also has a function to measure thru series/shunt impedance and port impedances.I used rather long alligator clips to connect. And I'm also not sure if my fixturing and cal process were very good. (Speaking of, does anyone have any good resources or books on the theory of fixturing and calibrating a VNA??)When I did a log-sweep on the analyzer, I got reasonable results, but I also did not get the resolution I wanted for lower frequencies.When I did a linear sweep, the results were very unstable at sub 100kHz. I'm scratching my head a bit here. Somehow the transfer function gain is >1 at many points. My hypothesis is that the sweep was too fast, or possibly, there is resonance at these lower frequencies.

author: Benta
author_rank: Super Contributor
timestamp: June 26, 2022, 08:46:31 pm
content: Could you post a picture of the thing itself? It looks like something I once designed.
Reverse engineering a classic audio product? - Page 1
Forum section: electronics / projects

author: cvanc
author_rank: Frequent Contributor
timestamp: February 21, 2020, 04:53:22 pm
content: OK audio types, here's something you don't see every day...Attached is the schematic for the Beveridge Electrostatic loudspeaker model 2SW-1. Back in the day it was argued to be one of the finest speakers ever made. Let's figure out how it works.It has a built-in hybrid amplifier that uses tubes for the output stage. The configuration is novel, allowing for transformerless drive to the transducer panels.I would love to discuss how the output stage works. Especially how does it bias the driver transistor pair, and how does the output node of the tubes stabilize at a quiescent state halfway between +HV and ground? I am not visualizing it...Thanks!

author: duak
author_rank: Super Contributor
timestamp: February 21, 2020, 06:55:24 pm
content: R1 & R3 look like feedback resistors to the driver stage. A higher cathode voltage on V201 & V203 leads to more base current into Q108 & Q109 then Q110 & Q111 turning them on harder, pulling the grid voltages of V202 & V204 up causing their plate voltages to fall and bringing the cathode voltages back to nominal. The actual voltage is a function of the voltage of the -60V rail and the values of the various resistors in the feedback circuit.
Reverse engineering a counterfeit 7805 voltage regulator - Page 1
Forum section: electronics / projects

author: FrankBuss
author_rank: Unknown
timestamp: September 06, 2014, 05:23:00 pm
content: Very interesting article how a 7805 works, down to the die level, with an interactive image where you can click on the die and it highlights the component on the die and in the schematic:http://www.righto.com/2014/09/reverse-engineering-counterfeit-7805.html

author: TimNJ
author_rank: Super Contributor
timestamp: September 06, 2014, 08:51:03 pm
content: Very cool. I like the interactive part. Chip design scares me sometimes because it just looks so much different on the microscopic scale vs macroscopic components.

author: TheAmmoniacal
author_rank: Unknown
timestamp: September 06, 2014, 09:40:49 pm
content: I've always wanted to make my own LM7805 from discrete components, but I'm not sure which transistors would be the best to use. The transistor layout is a bit confusing. Anyone know? Q1-19.

author: DanielS
author_rank: Frequent Contributor
timestamp: September 07, 2014, 06:02:37 am
content: Quote from: TheAmmoniacal on September 06, 2014, 09:40:49 pmIf by discrete you mean no multi-parts transistor packages (like quad-2N3904s) either, your biggest nightmare with attempting to create anything remotely as good as a 7805 from individual transistor will be matching transistors for current mirrors and differential stages to minimize offsets and drift. Another problem will be thermal coupling between those critical transistor pairs to mitigate thermal drift.The circuit is basically an opamp with an internal reference voltage connected to its non-inverting input and no low-side driver in its output stage.

author: mcinque
author_rank: Unknown
timestamp: September 07, 2014, 08:19:16 am
content: Very interesting, amazing job

author: EEVblog
author_rank: Unknown
timestamp: September 07, 2014, 09:51:53 am
content: That does it, I'm getting myself a decent high power microscope...

author: RobinF
author_rank: Newbie
timestamp: September 07, 2014, 10:13:02 am
content: Very well done article indeed!Except I don't agree that it's necessarily fake. On chips of that generation it was quite common not to have a manufacturer's ID on the die. Here are some examples of 741's, where you can see that in this case ST was actually the only one to include their logo, although you can also see that it was a 1992 redesign.

author: FrankBuss
author_rank: Unknown
timestamp: September 07, 2014, 11:34:07 am
content: Quote from: EEVblog on September 07, 2014, 09:51:53 amCool. Maybe ask Jeri Ellsworth if she gives you her electron microscope. Altough shipping might be more expensive than buying a local one in Australia (e.g.http://cgi.ebay.com/171444401873$1,999.99 for the microscope, $2,000 for shipping).
Reverse engineering a die shot of the UC3843 SMPS controller IC? - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: May 28, 2025, 08:16:49 pm
content: I'm interested in looking at the implementation details of the ubiquitous UC3843 SMPS controller. (or rather any of the x84x series or it's clones)As far as I am aware, transistor level schematics have not been published for the 3843 or any of its variants.To start I would like assistance figuring out the locations of the 8 pins in the attached die shot. I've never reverse engineered from a die photo before, I am looking to learn enough to reverse engineer this particular die.Also attached is a block diagram with pin numbers, and a datasheet.In particular, I am interested in looking that the oscillator. I expect it to be an open collector comparator that latches at 2/3 of the internal 5V reference, and unlatches at 1/3 of the internal reference. But I could be wrong.I am not quite sure how I would go about inferring which pin is which. I suppose there must be some large output transistors somewhere - and that might allow one to trace backwards through the control circuitry?

author: incf
author_rank: Frequent Contributor
timestamp: May 29, 2025, 09:38:16 pm
content: Turns out it may be unnecessary. This datasheet from TSC has a fairly detailed description of the internal operation of the oscillator block.

author: Whales
author_rank: Super Contributor
timestamp: May 29, 2025, 09:50:27 pm
content: Cheers for that datasheet, it has some nice extra details elsewhere in it too. I am currently working on a project where I might bypass the in-built opamp and replace it with my own external opamp control loop instead.
Reverse Engineering a Door Bell! - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: November 22, 2017, 01:00:18 pm
content: I am trying to reverse engineer a door bell design that I saw in a You Tube Video... ()...The circuit is really just made of a 4017 decade counter and a 40106 hex schmitt trigger.I've drawn out the part of the circuit for the three inputs (Front Door, Side Door and Rear Door) and it is this part of the circuit I am currently trying to understand. All gates are Schmitt Trigger inverter (I forgot to put the Schmitt trigger symbol in some triangles!)I have a number of questions!When the Rear door is pressed the P4DRV output rings the P4 chime and when the Side Door is pressed the P2 chime. The 6A6Y and 4A4Y gates look like they shape the output pulse but what is the purpose of 5A5Y?For the Front door there is an 8 note pattern (driven by the 4017 decade counter) and for this the 4017 needs to get a CLK.. How does the combination of 2A2Y and 3A3Y form an oscillator? (The 0 output from the decade counter indicates the end of the sequence... that should stop the oscillator?)Any hints appreciated!