hybridfree/eevblog-posts huggingface dataset:
Extra PCBs - Page 1
Forum section: electronics / beginners

author: Aggressive_Doughnut
author_rank: Contributor
timestamp: March 21, 2019, 12:33:30 pm
content: Hey all, sorry if this has been asked before but I can't find it if it has. What do you do with your extra PCBs? I have completed a bunch of projects, and each run of PCBs (including unsuccessful revisions...) was at least quantity ten, so now I have a few hundred extra unused PCBs floating around. Seems a shame to have to toss them in the garbage. I guess I could make an art project, but I imagine I would still have many left over.

author: Moriambar
author_rank: Unknown
timestamp: March 21, 2019, 12:44:01 pm
content: Quote from: Aggressive_Doughnut on March 21, 2019, 12:33:30 pmI try and reuse them. Sometimes the circuits are specific but with a bit of thinking, some jumpers, and pre-soldering stuff can be repurposed.The ones that are too specific go in the trash

author: KL27x
author_rank: Super Contributor
timestamp: March 21, 2019, 01:11:12 pm
content: Stage 1: hold onto all these PCB's in case they might be usefulStage 2: keep one example of each extra for a collection, filling up a shoe boxStage 3: put them in the trash as soon as you are done verifying the PCB

author: ataradov
author_rank: Super Contributor
timestamp: March 21, 2019, 10:40:54 pm
content: Was discussed herehttps://www.eevblog.com/forum/projects/what-to-do-with-extra-proto-pcbs/
Extract huge amount of data from Device in Debug(STM32) - Page 1
Forum section: electronics / beginners

author: Curby
author_rank: Contributor
timestamp: April 02, 2018, 02:15:47 pm
content: Hi there,I have a huge amount of data, I would like to extract to an Excel file. I have an array with the size of 10.000 of uint32_t. The whole Items shall be displayed as an chart.But I'm completely stuck how to export them. Eclipse just allows me to open this array in Debug in groups of 100 pieces. This way i need hours for copying them manually.I tried using the command dump, but what can I do with the binary oder intelhex data? If eclipse whould open all 10.000 elements at the same time, i could simply copy them. Addiotionally there is every 100 elements the drop down text, I have to remove manually. Horror!Can someone help me?

author: senso
author_rank: Frequent Contributor
timestamp: April 02, 2018, 03:07:28 pm
content: print then over serial port, comma separated, put into excel, done?Or simulate all that in the pc side first and do whatever you want with the date before testing code on the micro?

author: Curby
author_rank: Contributor
timestamp: April 02, 2018, 03:14:05 pm
content: I need real data, no simulation. I have only Midi and Audio outputs. Here is a picture of eclipse debugging to see what i mean. I could build a Midi to serial Adapter, but why if I have a debugger?

author: bson
author_rank: Unknown
timestamp: April 02, 2018, 09:03:39 pm
content: Install and learn to use openocd and dump it to a file. It's a worthwhile investment in time since this isn't going to be the last time an IDE can't do something simple you need.
Extremely simple USB-C power source - Page 1
Forum section: electronics / beginners

author: Saimoun
author_rank: Frequent Contributor
timestamp: May 17, 2024, 09:55:28 am
content: HiIs it possible to have a simple USB Type-C port on the host/source side without a USB PD chip? (for example turning on/off Vbus with transistors)All the port has to do is to transmit power, no data.Thank you

author: Saimoun
author_rank: Frequent Contributor
timestamp: May 17, 2024, 10:44:21 am
content: Would something like the attached circuit work for example?I understand connecting the CC pins together breaks the standard - but since all USB-C cables only connect one of the two it should work?

author: wasedadoc
author_rank: Super Contributor
timestamp: May 17, 2024, 11:08:36 am
content: Why do you want/need to switch the power? Just wire 5v and 0v to the appropriate pins of the socket?

author: tszaboo
author_rank: Super Contributor
timestamp: May 17, 2024, 11:50:56 am
content: You don't have to support power delivery for a Type-C port.I think for a 5V device the only requirements are to have two pulldown resistors on the CC1/CC2, so if you have a simple "OR" detection on these two lines, you can control a current limited power switch with that. There are dedicated USB power controllers as well.

author: Saimoun
author_rank: Frequent Contributor
timestamp: May 18, 2024, 09:18:42 am
content: Quote from: wasedadoc on May 17, 2024, 11:08:36 amIf you do that and two hosts are plugged into each other them boomTurning on the Vbus only when a device is connected is part of the spec

author: arrio
author_rank: Newbie
timestamp: August 17, 2024, 09:21:37 am
content: i think just use two diode can simpily fix the standard.It is worth noting that PMOS may not entirely "open" if you use 10k pull up resister (3.0A@5V), in this case you may use OR gate instead.New hands here, sorry if it offends :lol:
Ez Share Wi-Fi SD – has anyone managed to get Wi-Fi to start without a camera? - Page 1
Forum section: electronics / beginners

author: dj54dan@gmail.com
author_rank: Newbie
timestamp: August 19, 2025, 09:51:51 pm
content: I’m testing an Ez Share Wi-Fi SD adapter (for microSD) and I’ve noticed that Wi-Fi only starts when the card is inserted into a camera. If I put it in a regular OTG reader or just power it through a power bank, nothing happens – the LED doesn’t blink and no network shows up.Has anyone found a solution or hack to get Wi-Fi to start without a camera?– Could a microcontroller (Arduino/ESP32) be used to emulate a camera and trigger the card?– Are there modified card readers that can send the init sequence?– Or has anyone tried a hardmod directly on the card to force Wi-Fi on?I’m curious if anyone has solved this before, and if there’s documentation or projects I can look into. Any tips or experiences would be greatly appreciated!

author: amyk
author_rank: Super Contributor
timestamp: August 20, 2025, 01:50:44 am
content: According tohttps://n-o-d-e.net/beacon.htmlit just needs power to boot up, so perhaps you have a slightly different model that only starts its network if you try to access it via the SD interface, or requires more power than the card reader can provide?
EZP2023+ vs T48 (& T48 vs T56) ..perhaps suggest something else? - Page 1
Forum section: electronics / beginners

author: u666sa
author_rank: Frequent Contributor
timestamp: August 09, 2023, 02:18:46 pm
content: What I need:*In notebooks often programming flash fixes things and make it start. Also in DVB-T2 boxes. Plus older TV's and monitors, pre smart era, have those flash chips, often programming them fixes things.*Reading and changingEDID is a must. I just have to be able to do it.*Now there are some newer TV's and also some brand names from pre smart-tv era that use specialized chips which require special programmers, I don't care much about them, because they come in much less often, but it would be nice to have that capability.*Connecting through pins on board would also be nice. JTAG and other interfaces that are often found on boards. (edit.. I changed my mind,IT IS A MUST!)There is absolutely no information on these things, other than some unboxing videos, you get to see what adapters come in the kit. Plus there is a list of supported chips, which would be useful to look up a particular chip, I guess, but not very useful when deciding which programmer to buy.So what is the difference between EZP2023+ vs the XGecu T48?..What is the difference between XGecu T48 vs the XGecu T56?.......................As in what I would be able to program with one and not with the other?Now there is this programmer, UFPI, but it is out of my budget. (site,model comparison). It supports pretty much everything, I'd be happy to own it, except we talking about 400+ bucks with adapters and licenses. It supports this:1-WireEEPROM I2CEEPROM SPIEEPROM Microwire (3-Wire)SPI FlashUARTGPIOSD/eMMCNORNANDSerial NANDOneNANDBDMJTAGLOGGERMCUMount FileMount ChipWhat part of these futures do the above mentioned T48, T56 and EZP support?Perhaps you could suggest me some other programmer?///Back in 2016 my friend bought EZP for TV repair, suddenly he was able to reanimate things that he wasn't able to before. I even used his programmer to reanimate the very notebook I'm typing on right now, Thinkpad W520. So I know that EZP is excellent.

author: andriusATT
author_rank: Newbie
timestamp: May 07, 2025, 05:11:12 am
content: I'm in his boat,pretty much,I have the EZP2023+ and don't have any idea how to use it.I want to backup and restore EMMC chips and Bios files.but right now I have a CH341B chip on a CH341 Pro module that I want to use for UART ,but I'm scared to try I have looked alot and can not find anyone with the same module.Everyone says you have to do this and that to get 3.3 v and not 5v but its marked on my board!! With a header I'm so confused.
F-SW26 no-clean flux? - Page 1
Forum section: electronics / beginners

author: BlastFX
author_rank: Newbie
timestamp: November 25, 2018, 08:02:29 pm
content: I'm ordering new solder and I've noticed thedatasheet for Stannol's HS10which uses the F-SW26 (1.1.2) flux says it doesn't require cleaning.I was under the impression that F-SW26 was a bit too corrosive to leave on a PCB. Am I wrong or is Stannol?

author: dangerousamateur
author_rank: Contributor
timestamp: November 25, 2022, 10:58:12 am
content: This topic may be old, but I have the same question.Whats you opinion on this? I still have lots of F-SW26.Should I prefer F-SW32 or 34?

author: coromonadalix
author_rank: Super Contributor
timestamp: November 25, 2022, 05:32:22 pm
content: My comments would be : whatever the flux type or brandAlways do a board clean upI've seen some corrosion, residues who create problems in high frequency applications or sensitive high impedances circuits .... it created some input leakages ....I never let a board with flux on it, more than 4 hoursI've seen returned boards with corrosion under some parts one year after assembly ...my 2 cents

author: dangerousamateur
author_rank: Contributor
timestamp: November 25, 2022, 08:24:25 pm
content: Thanks for the answer.In fact I must say I don't make PCBs, I repair something sometimes... And I do a lot of RC modelling stuff.I have a feeling that some very old F-SW26 / 1.1.2B I have works better with old parts that have been sitting in the cellar for a very long time.But I never noticed any corrosion...Is that whole corrosion issue maybe a thing that just becomes relevant when SMD parts are soldered with a wave machine and the flux can accumulate on the underside, where the flux is not properly cooked?Maybe not even relevant in hand-jobs?
Fab Labs in China - Page 1
Forum section: electronics / beginners

author: dano000
author_rank: Newbie
timestamp: October 07, 2013, 08:47:01 am
content: Hey guys,First post ever, long time viewer. I was wondering if anyone has had any experience with getting PCBs made in China, specifically from any companies listed on alibaba.com? Most of them look quite dodgy to me, but I honestly have no idea.Any thoughts?Cheers,Dano000

author: Avi
author_rank: Contributor
timestamp: October 07, 2013, 08:52:48 am
content: I have twice used seeedstudio's fusion PCB service (Shenzhen, China). All boards work fine, looks ok to me. Only thing is, what is one to do with the other 9 boards! (10 minimum)

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: October 07, 2013, 08:56:49 am
content: Here'san article on companies I have used or are known good. It's reasonably up to date but read the comment thread for the latest updates.

author: cavlovic
author_rank: Contributor
timestamp: October 07, 2013, 11:46:42 am
content: Quote from: Avi on October 07, 2013, 08:52:48 amJust had a look at their website (they are also preparing a new design:http://www.seeedstudio.com/service/which is in beta) and they seem to offer 5 pieces now. I will give this a try once I have my first board ready

author: jechavarria
author_rank: Newbie
timestamp: October 07, 2013, 12:09:40 pm
content: I also use SeeedStudio and works fine!! All the PCB's I review in my blog are for these company:www.jechavarria.com

author: amyk
author_rank: Super Contributor
timestamp: October 07, 2013, 12:18:36 pm
content: If I remember correctly, Seeed don't make PCBs themselves but just serve as a "distributor" to variousothercompanies.

author: Psi
author_rank: Super Contributor
timestamp: October 07, 2013, 12:25:10 pm
content: I've had zero issues with PCBcart

author: jechavarria
author_rank: Newbie
timestamp: October 07, 2013, 01:12:31 pm
content: http://www.seeedstudio.com/depot/fusion-pcb-service-2-layers-p-835.html?cPath=70_71

author: herctrap
author_rank: Newbie
timestamp: October 09, 2013, 07:45:35 am
content: seeedstudio works also fine for me
Facia Removal On Hameg HM605 - Page 1
Forum section: electronics / beginners

author: JCEEVBLOG
author_rank: Newbie
timestamp: October 05, 2018, 11:16:02 am
content: Hi allJust got my first scope and it needs a good clean. I have removed the smaller knobs as they unscrew but...does anyone know how to remove this knob as I want to clean the face-plate and everything else as it has years of crud on it from previous owners YUKAlso cannot find anywhere a service manual for this in English anyone got any links or have a PDF that they would be willing to share?Cheers

author: GreyWoolfe
author_rank: Unknown
timestamp: October 05, 2018, 11:29:20 am
content: I will ask my first stupid question of the day, you did look all around the knob for a setscrew, right? I don't have a Hameg but my Tek 2465 has setscrews in the large knobs.

author: JCEEVBLOG
author_rank: Newbie
timestamp: October 05, 2018, 12:00:09 pm
content: Yup no screws anywhere.I have put reasonable force on it thinking it is on splines etc. but it didn't budge :-(

author: JCEEVBLOG
author_rank: Newbie
timestamp: October 07, 2018, 01:03:21 pm
content: There is a small disc of plastic that you have to remove from inside the knob which will reveal its mounting nut :-)
factory reset - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: January 09, 2010, 07:20:16 pm
content: Does anyone know how to do a factory reset on a fluke 789. please and thanks.

author: charliex
author_rank: Frequent Contributor
timestamp: January 09, 2010, 10:32:10 pm
content: I don't, or even heard of it , the manuals are here thoughhttp://www.tequipment.net/Fluke789ProcessMeterSP.html

author: Unknown
author_rank: Unknown
timestamp: January 18, 2010, 10:31:53 am
content: I haveFVF-SC2 FlukeView Formssoftware, and there is option for factory reset for DMM Fluke 189. I think that it can do the same job for Fluke 789. You can try with Hyperterminal or better alternatives, but you have to do some investigation to find right command for that option. After that you can to write some script/text file and send it to Fluke789.But, there are Fluke "short-cut" options for some another Fluke instruments:Fluke scope meters 123/124:1. Turn off instrument2.Press and hold "backlight" key3.Press and release "on/off" key (instrument will turn on and should hear double beep)4.Release "backlight" keyendFluke 43: device isturn off1.Press and hold "HOLD/RUN" key2.Press and hold "ON/OFF" key (should hear double beep)3.Release "HOLD/RUN" keyendFluke 187/189(problem is "SETUP" key at 789...):1.Turn on instrument2.Press "YELLOW"(SET) key and "BACKLIGHT" key (in that order!)3.Continuouslystep 2(should see different text on the screen) until appear "Fcty" on the screen4.You should see flashing "no"; choose between "yes" or "no" with "BACKLIGHT"(left) key and "BLUE" (right) key5.Final step is press "YELLOW" (SET) key----------------------------------------Note:If you want to step back, press "YELLOW" key and "%" key (CANCEL option).
Failed battery - Page 1
Forum section: electronics / beginners

author: fixit7
author_rank: Regular Contributor
timestamp: June 11, 2019, 03:28:16 am
content: I have had this for a few years.Charged it about 20 times.I had 2 of them and one UBL running some 12 volt leds.Both of the SkyWolfEyes went to 0 volts.I claims to have a protection circuit.The Sky ones weight 36 grams, 42 for the UBLs.https://imgur.com/a/3vUnHcJCould my UBL have been damaged?Thanks.

author: Daixiwen
author_rank: Frequent Contributor
timestamp: June 11, 2019, 06:19:44 am
content: Are those 18650 cells? If so they are probably fake, you can't have a 5000mAh capacity in that size with today's technology.
Failed DC transformer.  Interesting for a tear down? - Page 1
Forum section: electronics / beginners

author: Matt-
author_rank: Newbie
timestamp: November 04, 2018, 08:40:38 am
content: Hey all,I'm a long time lover of the channel and have had an electronics failure that I thought may be interesting for a tear down. It's a standard 240vAC -> 12vDC wall wart which has suddenly decided to start outputting double its rated voltage.Is this a common failure or is it worth sending in to Dave for some surgery?TIA.

author: Ian.M
author_rank: Super Contributor
timestamp: November 04, 2018, 09:00:39 am
content: Sounds like the feedback circuit has failed and is so crappy that there is no other limiting circuit so the primary side switched mode controller is running flat-out. IMHO its of very little interest as although its not a very common failure mode, one cracked track or open-circuit resistor is enough to cause it.Why not tear it down yourself and post about it here? If you don't feel up to doing a video, good photos and text are IMHO actually preferable as they take a lot less time to look at, and are easier to study in detail. If you do do a video, *KEEP* *IT* *SHORT*' - 5 minutes max.

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: November 07, 2018, 09:59:35 pm
content: I agree with Ian. Dave's a busy man right now, with two young kids and moving his lab. You have the time and resources to do this yourself and share your findings. Why don't you open it up and see what you find?

author: Jebnor
author_rank: Regular Contributor
timestamp: November 08, 2018, 05:01:48 am
content: Quote from: Matt- on November 04, 2018, 08:40:38 amYes;No.In that order.This is one of those where taking it apart yourself is safe (No plugged in of course) and you can see how it works. Look up "wall wart circuit" in your favourite search engine of choice and see if you can determine which circuit yours is using.Enjoy,Jeb

author: tpowell1830
author_rank: Frequent Contributor
timestamp: November 08, 2018, 05:11:44 am
content: Quote from: Matt- on November 04, 2018, 08:40:38 amHi Matt, welcome to the forum. I do not recommend sending this to Dave, however, if you wish to tear it apart and try to understand it, Big Clive does this on his channel very often and reverse engineers these types of supplies all the time.Check him out here:https://www.youtube.com/user/bigclivedotcom/videosHope this helps...
Failed logon attempt - Page 1
Forum section: electronics / beginners

author: fixit7
author_rank: Regular Contributor
timestamp: October 07, 2024, 12:34:51 pm
content: How do I stop this ?Code:Hello fixit7,We have detected a failed login attempt on your account.IP address of the failed login attempt: 184.52.107.19

author: thm_w
author_rank: Super Contributor
timestamp: October 08, 2024, 12:50:04 am
content: Make sure you are using a secure password, and that password is not being re-used on other accounts. If its the case you can ignore it.https://www.eevblog.com/forum/chat/my-account-is-being-hacked/
Failed to connect to ESP32. No serial data recieved - Page 1
Forum section: electronics / beginners

author: Mia Barn
author_rank: Newbie
timestamp: September 28, 2024, 06:34:46 pm
content: Hi, I need some help. My ESP32 was working fine yesterday but today, it's showing an error. I changed USBs, and ports, updated the driver, and done everything, but it does not recognize my ESP32. The board and ports seem connected, and the laptop has a connecting sound when I connect ESP32.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: September 28, 2024, 07:40:52 pm
content: COM port number likely changed on you. Go into Device Manager and check
Failure in implementing LM7805 and LM7905 in LTSpice! - Page 1
Forum section: electronics / beginners

author: ruiseixas
author_rank: Contributor
timestamp: May 10, 2017, 10:52:09 am
content: Hi,After seeing dome youtube videos and reading LTSpice libraries, I try to implement the vulgar LM7805 voltage regulator without success.The library file I'm using for LM78xx and LM79xx is this one here:http://ltwiki.org/files/LTspiceIV/lib/sub/regulators.libFor the LM7805 the library states this:Code:* LM7805 model.* No need to use .inc - I've set the .asy symbol to remove the need for .inc.* (I used the symbol of LT1084, just replaced the LT1084 by LMxxxx and LTC.LIB by regulators.lib)However after I followed the instructions to adapt the LT1084 symbol I got this error when try it the simulation:Unknown subcircuit called in:xu1 nc_01 n001 regulators.lib lm7805?Here is the obtained LM7805.asy file after replacement and edition:Code:Version 4SymbolType CELLRECTANGLE Normal -128 -64 128 96TEXT 0 0 Center 2 LTWINDOW 0 0 -63 Bottom 2WINDOW 3 16 112 Left 2SYMATTR Value LM7805SYMATTR Prefix XSYMATTR SpiceModel regulators.libSYMATTR Description LM7805 Voltage RegulatorPIN 0 96 BOTTOM 8PINATTR PinName ADJPINATTR SpiceOrder 1PIN 128 0 RIGHT 8PINATTR PinName OUTPINATTR SpiceOrder 2PIN -128 0 LEFT 8PINATTR PinName INPINATTR SpiceOrder 3Any ideas how to do this properly?

author: ruiseixas
author_rank: Contributor
timestamp: May 10, 2017, 12:52:55 pm
content: Problem solved with these libraries instead from theYahoo! group LTSpice:https://groups.yahoo.com/neo/groups/LTspice/files/%20Lib/Linear%20Regulators/LM78xx%20and%20LM79xx%20files/Just place all .asy files in "LTspiceXVII\lib\sym\PowerProducts" folder and all .lib files in "LTspiceXVII\lib\sub" folder!
Failure prediction: applying 21V (over voltage) to logic level translator  - Page 1
Forum section: electronics / beginners

author: davegravy
author_rank: Regular Contributor
timestamp: December 11, 2024, 07:34:14 pm
content: I have theTXU0204RUTRbetween my SBC's UART interface and a cellular module's interface. Let me know if schematic is helpful here but it's a pretty standard connection between two UART interfaces.Due to clumsy probing I think I accidently shorted 21V to one or more of the B1Y, B2Y, B3 or B4 which is the SBC side of the translator. Aside from destroying the SBC's UART interface and the TXU204 I'm wondering where else to expect damage.I replaced the SBC and the TXU204 but either I have solder issues under the translator or the translator did not protect the cellular module and it's interface is also toast. I've tried resoldering the TXU204 a couple times (the UQFN pin pitch is extremely fine and easy to botch soldering IME) but can't get communication back. I could try swapping the module but it's very expensive and difficult to desolder so it would be helpful to know the likelihood that it's damaged. I have no access to the signals on the PCB to test, unless I scrape off / expose track copper.

author: PGPG
author_rank: Frequent Contributor
timestamp: December 11, 2024, 07:50:08 pm
content: In my opinion there is very, very little chance this IC (with absolute maximum supply 6.5V) to protect anything against 21V.If it were digital signal insulator then 21V from one side would probably not go to the other, but only probably as insulation is very thin and not protected against practically exploding half of circuit.
Fairchild application note resistor values - Page 1
Forum section: electronics / beginners

author: argintviu
author_rank: Contributor
timestamp: May 26, 2021, 06:07:23 pm
content: Hello! I am interested in building the curve tracer from AN6610 by Fairchild (https://www.onsemi.cn/pub/collateral/an-6610cn.pdf) and I was wondering about the resistor selection for the 10V and -10V references for the A4 op amp. These voltages are generated with the 499R + 1K (+10V) and with the 499R + 1k + 750R (-10V) dividers.I was thinking of using SMD resistors, but since the values of these resistors are small, I'm afraid the resistors will burn or heat up too much and drift. Is there any special reason to why the author has chosen such small values? Lower noise maybe? Could I change them to something bigger to minimize dissipation? Any suggestions for a range?Also, what's the purpose of the 10R resistors that go to the drain of the DUT? Could they be omitted?

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 26, 2021, 06:35:08 pm
content: Dissipated power is I*I*R, or U*U/R.

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 26, 2021, 07:12:38 pm
content: You may successfully use two 1k resistors in parallel instead of 499R, and two 2k instead of one 1k - and everything will be fine with power dissipation if you are afraid of it.

author: argintviu
author_rank: Contributor
timestamp: May 27, 2021, 03:43:49 am
content: Thanks for the input!
Fake crystal? - Page 1
Forum section: electronics / beginners

author: Raj
author_rank: Frequent Contributor
timestamp: November 09, 2017, 08:36:36 am
content: I was trying to send data to atmega8 board (picture below).The crystal on the board reads kds-16.000the code inside of atmega8 is(recieve bit and send it to portC ,UBRR=0067)Quotethere's an led on portC's second pin which will toggle on-off if the code works fineI am sending 0xFF and then 0x00 to atmega8 using chinese arduino nano.but the thing is-My expecation was the following code would work-(send 0xFF and 0x00 alternativly after short delay baud rate9600)QuoteBut the one that works is-(send 0xFF and 0x00 alternativly after short delay baud rate1200)QuoteMy calculation says that an atmega8 running at 16mhz should be set for 9600 baud rate if the UBRR is set to 0067but when I did that,Why does it work only at baud rate of 1200Is the crystal,a fake and is 8 times slower than what I think?btw..The fuse values are unchanged sinced it's out of the box.another question.is there a ciircuit to test the frequency of a crystal.I have many unmarked crystals.Sorry for a wall of text

author: Raj
author_rank: Frequent Contributor
timestamp: November 09, 2017, 08:43:28 am
content: Quote from: blueskull on November 09, 2017, 08:38:33 amWish I had one

author: mikerj
author_rank: Super Contributor
timestamp: November 09, 2017, 09:15:47 am
content: Check the configuration fuse settings, the AVR may be running from the internal RC oscillator rather than the crystal.

author: Raj
author_rank: Frequent Contributor
timestamp: November 09, 2017, 09:41:00 am
content: ouch! problem with fuse-high D9 low E1 lock FF(internal rc oscallator,at 1mhz)But it's still half the story16/1 not equal to 9600/1200
Fake MOSFET? - Page 1
Forum section: electronics / beginners

author: Nogtail
author_rank: Regular Contributor
timestamp: September 25, 2016, 03:25:01 am
content: I recently got some components from eBay and most of them have turned out to work fine. I have had problems with some of the MOSFETs however, with shorts between the source and drain and them not being able to handle even a few amps.I went a bit medieval on some of the dead ones and a (dead) genuine IPD50N03S2-07 (marked PN0307) for comparison. The dies inside the eBay MOSFETs are tiny in comparison to the genuine PN0307, even when specs look similar. Have I been sold fakes, or is this some fancy new small process?

author: wraper
author_rank: Unknown
timestamp: September 25, 2016, 04:58:56 am
content: ebay is full of fakes. Actually many of the parts which are easy to counterfeit are nearly impossible to buy genuine.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: September 25, 2016, 05:19:43 am
content: Rod Elliott's take:http://sound.whsites.net/counterfeit.htmPower devices seem particular favorites of these criminals.

author: all_repair
author_rank: Frequent Contributor
timestamp: September 25, 2016, 10:59:57 am
content: They are fake. File for claim and leave a negative feedback. Do not be guided by the seller even he has 99.98% good rating. I gave the benefits of doubts to polita (can't remember the exact ID now) many years back. Lost 100USD, sent back and they claimed non-receipt and I missed the feedback window. Ebay and paypal walked out on me.The best thing that happened was now I buy direct from China.
faking a full battery for charging circuit - Page 1
Forum section: electronics / beginners

author: kolonelkadat
author_rank: Regular Contributor
timestamp: May 16, 2015, 05:17:15 am
content: I recently got a bts-06 bluetooth speaker on ebay with the in tention of repurposing it. I absolutely do not want the battery as part of the new device. With battery removed and powered from 5v in, it runs for a spell and then shuts off.I know Li ion batteries are like 3v6 - 4v1 or there abouts. But is it safe to connect my ~5v supply to the battery pinouts or is there some other trickery i should employ?Ive tried looking up datasheets to no avail.

author: DavidMenting
author_rank: Contributor
timestamp: May 16, 2015, 09:01:57 am
content: The battery charging circuit most probably measures the voltage of the battery to determine a fully charged state. A fully charged Li-ion battery will never reach 5V, so the circuitry might not be able to withstand that.To drop the 5V down to 4. something Volts, you could connect one or two diodes in series or hook up an LDO regulator set at 4.4V or thereabouts.

author: Delta
author_rank: Super Contributor
timestamp: May 16, 2015, 11:45:40 am
content: Replace the battery with a biggish cacapacitor, then power the device as normal (via usb?). The cap should keep the charging circuit happy by giving it something to squirt current into and watch the voltage rise...

author: kolonelkadat
author_rank: Regular Contributor
timestamp: May 17, 2015, 08:53:03 pm
content: Quote from: Delta on May 16, 2015, 11:45:40 amvery clever. this seems to have done the business. I wish i had bigger than 4700uF caps laying around though.
Fakra connectors?  - Page 1
Forum section: electronics / beginners

author: Sounduser
author_rank: Contributor
timestamp: October 19, 2018, 06:32:31 pm
content: Hi.Anyone know about fakra connectors?I want to change the stereo in my Jeep. It has a white fakra connector for the fm radio. The white adaptor cables seem to be hard to find here (UK)Are the other colours the same size pin with the plastic cases all being keyed differently? Or are all the colours pins and barrels various sizes?Thanks.

author: german77
author_rank: Regular Contributor
timestamp: October 20, 2018, 01:23:46 am
content: Mouser has 181 different connectors. With 14 different colors.https://www.mouser.mx/search/refine.aspx?Ntk=P_MarCom&Ntt=169532402

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: October 20, 2018, 03:13:25 am
content: In my experience the terminations are identical, just the connector receptacle is keyed differently - there may be some crossover in the keying between colours, I don't recallIf you're in a pinch it probably wouldn't be too difficult to modify the key with a dremel or similar

author: Sounduser
author_rank: Contributor
timestamp: October 20, 2018, 06:49:46 am
content: Mouser didn't seem to have any type b white connectors in stock...I was hoping to remove the plastic housing or make it fit.. Thanks. I'll try.

author: Sounduser
author_rank: Contributor
timestamp: October 22, 2018, 06:39:12 pm
content: Turns out the water green is universal.
Fallout New Vegas Zenith Royal 1000 radio repair - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: May 28, 2017, 06:22:02 am
content: This is totally like Fallout New Vegas, if u had to find and repair a radio. I wish there was such places around here. Here, its getting hard to even find CRT TVs for free lately in the classifieds, let alone old cool stuffand if u never heard of FO:NV his a peekCamp Searchlight and the Legion's Bag of Dirty Tricks - Fallout New Vegas Lore
false/2nd solder pad raised off pcb. what is it? - Page 1
Forum section: electronics / beginners

author: Brian Rourke
author_rank: Unknown
timestamp: July 22, 2019, 11:23:43 am
content: so i ordered a few 18650 pcm/bms.the board has solder pads to connect wire or nickle strips but they're raised off the surface of the pcb.when you heat and apply solder the surface slides around. at first i though i had lifted the pad.because i have 10 and they're so cheap decided to play around with it. I pulled that pad straight off the pcb,beneath it was another pad at the vertical level of the pcb. at 350c I left my iron on it trying to de-laminateit, even after a dozen seconds and scraping w tweezers that second pad wasn't coming off.I wanted to know, whats the point of these, what purpose do they serve?What are they called?Thanks all

author: Psi
author_rank: Super Contributor
timestamp: July 22, 2019, 12:10:48 pm
content: I've seen those things as gold plated SMT pads as part of a PCB switch contact.etc.https://www.harwin.com/product-highlights/pogo-pins-pads/Like for example if you wanted to make your own mechanical switch using a piece of metal touching the PCB.For the contact point you might want a hard gold plating however doing that to the entire PCB is expensive. So you use small SMT hard gold pads that can be placed and soldered to the PCB as part of the normal SMT assembly process.I assume you have a similar thing expect it's obviously not gold. Maybe it's a silver contact.However i cannot tell you why it's there. There doesn't seem to be a reason to use it.Maybe that PCM/BMS is part of some bigger assembly and it clips into a holder where it touches some other contact to connect to the cells

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 22, 2019, 12:13:43 pm
content: My guess is that it's for spot welding, you don't want to do that on a solder pad

author: Psi
author_rank: Super Contributor
timestamp: July 22, 2019, 12:15:39 pm
content: YeahThat would make perfect sense.

author: Brian Rourke
author_rank: Unknown
timestamp: July 22, 2019, 01:50:39 pm
content: I think you may be right. I saw a battery pack advertised and it appeared as if nickle strip was spot welded to a similar pcm.Its just a unique feature. I really want to know what they're called. After removing it i still had continuity from the pad below along the trace.

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 22, 2019, 06:33:19 pm
content: I did a bit of googling and it seems that they are just cut out of a nickel strip and soldered to the pcb.

author: james_s
author_rank: Super Contributor
timestamp: July 22, 2019, 06:52:59 pm
content: That's exactly what they are. I removed them from mine because I was soldering wires to the pads and the nickel was harder to solder to.
falstad is making my transformers work with dc current!! - Page 1
Forum section: electronics / beginners

author: robowaffe
author_rank: Regular Contributor
timestamp: July 05, 2023, 02:51:39 am
content: Here is a link to the simulation.https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAUgoqoQFMBaMMAKADcQ09OAWKlPryrCQgpCJgIWAJyFzMKOVVYAVThkUCq2BJsFUe4UdFLFdkBHiwkUYMyAY8TBFMTS6eO4mHIxTLAHd1TQ1OfGCoQLDuBWilKJ09bV0IyBYgAThis cant be correct!! whats the meaning of this?<edit>Im getting current on the secondary of the transformer on my computer - is this happening on yours too - or is it just a glitch on my computer?

author: ataradov
author_rank: Super Contributor
timestamp: July 05, 2023, 03:08:01 am
content: Here is an explanationhttps://www.falstad.com/circuit/e-transformerdc.htmlIncrease simulation speed to see it die down faster.Or decrease the inductance. 4 H is a lot.

author: robowaffe
author_rank: Regular Contributor
timestamp: July 05, 2023, 03:12:06 am
content: Ah thankyou! thats what it was!!!

author: ArdWar
author_rank: Frequent Contributor
timestamp: July 05, 2023, 03:12:29 am
content: Well if you have zero wire and load resistance that kind of thing do happen...

author: ataradov
author_rank: Super Contributor
timestamp: July 05, 2023, 03:14:22 am
content: It will still be the same with a real load. 4H coil inductance, the initial transient response takes a long time to settle.
Fan Motors - which kind? - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: June 27, 2017, 04:44:05 am
content: I have two 9 inch floor fans. One motor looks radial with 4 or 6 coils oriented around the rotor. The other has one coil offset on the laminations to the side of the rotor. Is one style any better than the other? The radial style fan is stated 60W and the other is calculated as 72W from the current*amp rating.

author: capt bullshot
author_rank: Super Contributor
timestamp: June 27, 2017, 08:08:50 am
content: Don't know about the radial style motor, but the other one is well known for its ineffiency - lots of electrical power wasted to heat. These are simple and cheap to make, but real energy wasters.

author: Circlotron
author_rank: Super Contributor
timestamp: June 27, 2017, 09:21:30 am
content: Sounds like the second one is a shaded pole motor. Nobody makes big ones because they are pretty awful.https://en.m.wikipedia.org/wiki/Shaded-pole_motor

author: metrologist
author_rank: Super Contributor
timestamp: June 27, 2017, 01:49:53 pm
content: Well, I found this, but when searching I was getting convinced that the other motor was a permanent split capacitor motor. It does have a large square capacitor that the shaded pole motor does not have.The outer windings are like these, only I think there are more than 4:https://www.psp.uk.com/shaded-pole-motors/

author: james_s
author_rank: Super Contributor
timestamp: June 29, 2017, 10:06:55 pm
content: PSC motors are fairly common in medium-large fans, large in the domestic consumer sense anyway. Shaded pole motors are pretty standard for small desk fans, they're cheap and reliable.

author: metrologist
author_rank: Super Contributor
timestamp: June 29, 2017, 11:43:14 pm
content: It's rather trivial. I wanted to keep the better design. Since they are both 9" fans, and I do not have a good way to measure actual air movement, I might just pick the lower wattage unit, but also consider longevity. I keep this one, but still cannot say what type of motor it has. (fans have been kind of sore spot because it gets hot here and a couple have burned out)
Fan Problems - Page 1
Forum section: electronics / beginners

author: Mighty Burger
author_rank: Regular Contributor
timestamp: April 22, 2016, 03:38:26 am
content: I'm creating my first permanent project. It's going to be a fan that can be powered by batteries or a wall adapter. It also has a speed control, which is the problem. I'm using PWM, and I'm fairly sure it works, but I don't have asillyscopeoscilloscope to test it. However, the fan's reaction to it doesn't. I'm testing it with a fan from an old computer before I place my very fast and slightly expensive fan into the circuit. Normally the fan (now talking about the old fan) spins perfectly, with 12 volts, and it spins even down to 3 volts. I've been told controlling the voltage is a poor way to control the fan speed, so I've went with PWM. Here's the circuit:(Note: in testing I eliminated the barrel jack and just used the batteries as a power source.) However, when I turn it on it makes a silly noise:https://www.youtube.com/watch?v=UbJRvniuXgg&feature=youtu.beThe moments when it is silent is when no power is connected. It wiggles and makes the strange noise when I connect power to it. The noise also changes pitch when I change the PWM duty cycle.I hope the solution to this issue is to simply replace one or two components. I really don't want to redo the whole circuit, but if I have to, I will. I hope reducing C1's capacitance would probably fix it?One last thing to note. The fan in the video is the old fan, and it doesn't have a 4th wire. However, the new fan does have a 4th wire. This extra wire is there for the computer to control the fan speed, but no google search is giving me any answers to how to take advantage of that extra wire. The only information I've collected is that doing so would be very difficult and would require a lot more components. I'm just going to PWM the power.

author: Mr.B
author_rank: Unknown
timestamp: April 22, 2016, 03:45:51 am
content: PWM the power is not the best way to do it. (And sometimes not the way to do it at all.)That 4th wire you are talking about is for sending a PWM signal to the fans own internal speed controller.Perhaps have a read of this article:http://www.overclockers.com/pwm-fan-controller/

author: Monkeh
author_rank: Super Contributor
timestamp: April 22, 2016, 03:48:59 am
content: Quote from: Mighty Burger on April 22, 2016, 03:38:26 amhttp://www.formfactors.org/developer%5Cspecs%5C4_Wire_PWM_Spec.pdfNot difficult, not remotely. Ponder why they'd introduce a method of controlling fan speed which is more difficult and expensive..QuoteDon't.

author: michaeliv
author_rank: Frequent Contributor
timestamp: April 22, 2016, 05:17:59 am
content: What MOSFET are you using ?Try spinning up the fan by hand and then connecting the power, does it work then ?

author: Marco
author_rank: Super Contributor
timestamp: April 22, 2016, 06:13:00 am
content: Quote from: Monkeh on April 22, 2016, 03:48:59 amCause they didn't want a high dI/dt signal across the cable presumably. The driver/tach circuitry could have used a rectifier and smoothing capacitor to get consistent power with direct PWM control, so that doesn't matter.
fan vs power supply - Page 1
Forum section: electronics / beginners

author: daniel444
author_rank: Regular Contributor
timestamp: November 11, 2022, 05:29:06 am
content: i just got this fan and ac to dc power supplyproblem is the fan turns on for 2 seconds then goes off for 2 seconds repeatedlythe fan runs fine off a batterythe fan draws 1.5 amps and the supply only puts out 0.8 amps , but i wasn't intending on running the fan at full speedis the problem just an undersized power supply??

author: BeBuLamar
author_rank: Super Contributor
timestamp: November 11, 2022, 12:38:31 pm
content: I think it's the power supply that shuts itself down due to overcurrent.

author: daniel444
author_rank: Regular Contributor
timestamp: November 13, 2022, 05:10:08 am
content: looks like your correct , i just ran it off different 12v supply and was able to fully speed adjust the fan with a simple 100ohm pot

author: daniel444
author_rank: Regular Contributor
timestamp: November 13, 2022, 05:23:41 am
content: update , if i start the fan off at a low speed and turn up the speed via the 100ohm pot im able to get 1.5 amps out of the original meanwell power supply that before was cutting in and out, and has a max of 0.8 amps

author: andy3055
author_rank: Super Contributor
timestamp: November 13, 2022, 05:28:03 am
content: Very soon that power supply will go kaput!

author: bidrohini
author_rank: Regular Contributor
timestamp: November 13, 2022, 06:30:26 am
content: I think using a 12V,2A power supply will be fine.
Fan yellow wire.  - Page 1
Forum section: electronics / beginners

author: Marduk
author_rank: Newbie
timestamp: March 12, 2013, 09:14:53 pm
content: hello all.. i was looking to find some info about the yellow wire on PC fan or 3 wire fans other then the Pos and gnd. what is the 3 wire use for temp sensor or speed control?

author: Kremmen
author_rank: Super Contributor
timestamp: March 12, 2013, 09:37:46 pm
content: Speed control. You get a pulse train from the wire when the fan is turning.

author: mariush
author_rank: Super Contributor
timestamp: March 12, 2013, 09:40:32 pm
content: sense = fan reports number of rotations to motherboard by sending 2 pulses for every rotationcontrol = motherboard sends signal used by fan to adjust its speed3 wire fans don't have the control wire.The colors are sometimes different, for example I saw the fourth wire colored green. But if the fan is to be used with computers, the order is this one all the time.

author: TerminalJack505
author_rank: Super Contributor
timestamp: March 12, 2013, 10:33:15 pm
content: If it is a three wire fan then most likely the third wire is a tachometer output. The output will be wired as an open collector. To use the output you'll have pull it up with a resistor to Vcc. The open collector allows Vcc to be (within reason) any arbitrary positive voltage.Most fans will pulse twice per revolution. You can use the rate of the pulses to determine the fan's speed.

author: ivan747
author_rank: Super Contributor
timestamp: March 12, 2013, 11:42:53 pm
content: This pin serves to measure the speed of the fan in RPM. If my memory serves me well, you connect a pull-up resistor on this pin and the output should give you 2 pulses per revolution. If you are not familiar with pull-up resistors:http://en.wikipedia.org/wiki/Pull-up_resistor
Faraday bag against a raspberry  - Page 1
Forum section: electronics / beginners

author: epigramx
author_rank: Regular Contributor
timestamp: March 13, 2019, 07:39:28 am
content: I noticed that a raspberry (and a powerbank) inflict serious interference to a gnss module/antenna above it and using a regular antistatic bag under that antenna/gnss module improves the gnss signal quality significantly.I wonder on the best practices to shield the receiver. If I wrap the raspberry in a regular antistatic bag, will the small holes for the connections leak a lot? Is it enough to just lay the bag under the antenna?

author: Whales
author_rank: Super Contributor
timestamp: March 13, 2019, 09:52:36 am
content: It's worth noting that 'near field' and 'far field' interference interact differently.If it's near-field magnetic then a layer of metal (eg ESD bag) between the two might improve things, even if there are gaps around the sides.Also be wary that your faraday bag is becoming part of your antenna. Check what type of mounting your antenna is designed for -- onto metal ground surfaces or is it designed for use far away from anything metallic? Balanced or unbalanced antenna?

author: ogden
author_rank: Super Contributor
timestamp: March 13, 2019, 10:17:40 am
content: Aluminium foil is way better quick & dirty, low cost shielding solution. Make sure you get as thick as you can find.

author: radiolistener
author_rank: Super Contributor
timestamp: March 13, 2019, 10:46:03 am
content: Quote from: epigramx on March 13, 2019, 07:39:28 amit's better to use copper foil. Something like that:https://www.aliexpress.com/item/99-9-High-Purity-Copper-Sheet-Cu-Metal-Flat-Foil-0-2mm-Thickness-Pure-Copper-Plate/32882328573.htmlYou're also should note, that interference can go through wires (power or signal).Small holes will not affect significantly.

author: epigramx
author_rank: Regular Contributor
timestamp: March 13, 2019, 07:22:31 pm
content: Quote from: Whales on March 13, 2019, 09:52:36 amQuote from: ogden on March 13, 2019, 10:17:40 amQuote from: radiolistener on March 13, 2019, 10:46:03 amI did use a copper-clad board before I tried the antistatic bag and it improved almost nothing. I suspect the EMI/RFI from the raspberry or/and powerbank affects the "new ground plane" formed by the copper board while an antistatic bag because of its irregularity keeps it not part of the antenna somehow.Quote from: Whales on March 13, 2019, 09:52:36 amI have doubts on that because a copper-clad board (which I tried) has completely different behavior (it seems to not be an improvement against EMI/RFI). Bags appear to not be antennas [maybe their shielding is too irregular to act like that or there's another factor].
Faraday cage for around 1MHz - Page 1
Forum section: electronics / beginners

author: anvoice
author_rank: Frequent Contributor
timestamp: July 02, 2020, 05:58:29 am
content: Hello, I'm looking to build a Faraday cage for a home brew NMR machine. The parts of the machine which will generate noise and need to be shielded from noise are the AC coils, and mine will be operating in the single digit MHz range. The coils (a few turns of copper wire) will fire short bursts at field strengths of less than a tenth of a mT. Would I be ok using something like 1/16" steel plate for the cage, in order to block outgoing radio noise? Also, do I need to ground the cage, and if so, what should act as the ground?