hybridfree/eevblog-posts huggingface dataset:
Broke off an inductor from 3090 Video Card. Can't find replacement part. - Page 1
Forum section: electronics / beginners

author: Blarney
author_rank: Newbie
timestamp: October 04, 2024, 09:30:42 pm
content: Hello. I hope this is okay to post here. I'm feeling stuck.I rather silly-ly broke off a component from my RTX 3090. I was hoping for some help finding a replacement part or some advice. The metal block of the inductor came off but the metal connectors? are still stuck to the board.I've measured it the best I can at 6.65mm x 6.75mm x 3.73mmFrom what I understand it's a 4.7uh inductor (4R7), but there's lots to choose from. I've attached some photos to illustrate.Thank you to anyone who can offer assistance

author: indeterminate
author_rank: Regular Contributor
timestamp: October 05, 2024, 02:41:01 am
content: https://au.mouser.com/c/passive-components/inductors-chokes-coils/power-inductors-smd/?height=3.3%20mm%7C~4.2%20mm&inductance=4.7%20uH&length=6.4%20mm~~6.8%20mm&width=6.4%20mm~~6.6%20mm%7C~6.8%20mm&instock=y&rp=passive-components%2Finductors-chokes-coils%2Fpower-inductors-smd%7C~Length%7C~Width%7C~Height

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: October 05, 2024, 04:17:18 pm
content: Personally I think your best bet would be get an identical inductor from the exact same GPU model (pulled from a dead card). There's so many variables to inductors that isn't solely inductance (Q factor, SRF, core material, and much more that I don't know about) that it's safest to grab an identical inductor. Using the wrong inductor can lead to various issues like excessive heating, poor voltage control, inability to hit peak currents, and more.

author: 16bitanalogue
author_rank: Regular Contributor
timestamp: October 06, 2024, 04:18:25 pm
content: Agree with finding a broken board and pull off that specific inductor. If this was not a high end card, I would say just measure the inductor and find any old inductor that matches the inductance. "Good enough" as they say.But if you have the fortitude, I found a website that has the schematics and board view:https://www.badcaps.net/forum/document-software-archive/schematics-and-boardviews/3474188-nvidia-geforce-rtx-3080-rtx-3090-schematic-board-view
Broke pins off TO-220, solder new wires on ? - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 24, 2017, 09:02:52 pm
content: I found a PCB on the street today, its been ran over and is rusting. It has 2 nice 16-pin PWM MOSFET drive chips on it, hopefully they still work, It might be from an induction heater style stove topOr some type of inverter ?Anyways I have a few TO-220 chips that I've pulled from stuff like today, and the pins sheared right off flush to the plastic. Can I solder on new wires on ? I have flux, files, sharpening stones, so I should be able to get a clean copper surface.

author: wraper
author_rank: Unknown
timestamp: April 24, 2017, 09:04:45 pm
content: you can but that will be very unreliable.

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 24, 2017, 10:28:45 pm
content: I'm wondering since there's so little to try and solder to that I would cook the chips. Thats fine but is there any tips ? Otherwise they are garbage anyways

author: RoGeorge
author_rank: Super Contributor
timestamp: April 24, 2017, 10:40:56 pm
content: Sure you can. You can even decap a small region near the broken pin using a Dremel against the plastic case, in order to expose more metal for soldering.The link is to see what is under the plastic case:https://siliconpr0n.org/wiki/doku.php?id=decap:explosive
Broken KEB vfd - Page 1
Forum section: electronics / beginners

author: Nuzi
author_rank: Newbie
timestamp: January 01, 2021, 07:40:36 pm
content: Hi allI been trying to fix an old keb vfd and after a few blown igbt-s i found out that 3 of the control signals were dead but when i probed the output of the gate transformers there is a signal present.Between the gate of the igbt and the transformer is a little red card with a circuit on it that gets warm so i guess its broken.I really dont know what that circuit is cant really find much info about it or if it can be replaced with discrete components.Any suggestions?
Broken Potentiometer? - Page 1
Forum section: electronics / beginners

author: Charkel
author_rank: Contributor
timestamp: January 24, 2018, 06:21:00 pm
content: I bought a couple switches and stuff to play with and I got a 10K Potentiometer.When I measure with one on middle pin and other on left/right i start at 0 and work my way up to Exactly 6K ohm and 60% on the knob when my meters screen suddenly flashes and starts reading 0.6K ohm instead and goes from there to like 2K ohm.Is it borken?

author: Paul Rose
author_rank: Regular Contributor
timestamp: January 24, 2018, 06:28:25 pm
content: QuoteProbably. But the "exactly 6K ohm" is a little suspicious. Could be meter changing ranges and messing something up.Try putting a DC voltage ( like a 9V battery or soemthing ) across the outside pins, and mesuring DC volts from negative side to middle pin. You should get smooth voltage change from 0V up to 9V ( or whatever voltage you used ) as you turn the knob.

author: sevenofnine33
author_rank: Contributor
timestamp: January 25, 2018, 09:04:20 pm
content: Connect it to batteries like said above. When measuring from outer pins you should get full resistance of that potentiometer. When measurin from middle and one outer pin you should get the resistance depending on how much you turn the knob.But since the screen flashes I guess that your multimeter is broken or faulty, buy another potentiometer of same resistance and check for yourself, or try measuring other components you have.
broken probes - Page 1
Forum section: electronics / beginners

author: yes955
author_rank: Newbie
timestamp: May 18, 2014, 11:04:31 am
content: Hello I have an old analog oscilloscope. It works fin but sadly I have broken the probes and was wondering if I can just buy some random pair form eBay or they need to have some special specifications?The oscilloscope has the name OS250 (10MHz) and the service manual can be found her:http://elektrotanya.com/advance_os-250_oscilloscope_10mhz.pdf/download.html

author: Simon
author_rank: Unknown
timestamp: May 18, 2014, 12:18:30 pm
content: just get any new pair that are at least 10 MHz, you will need to redo the compensation adjustment on the new probes and that is it

author: yes955
author_rank: Newbie
timestamp: May 18, 2014, 12:45:48 pm
content: Ok. Thank you
Broken terminal on PSU - Page 1
Forum section: electronics / beginners

author: iceisfun
author_rank: Regular Contributor
timestamp: June 17, 2013, 04:38:14 pm
content: I have a PSU that I got off amazon and I never had the need to use both terminals until now when I found this problemThe ground terminal on the second part does not hold banana clips tightly, they just flop around, here is a picture of the terminal in questionhttps://www.iceisfun.com/psuterminal.pngIs this kind of terminal a standard thing I could replace? Was it just machined wrong?ps - don't ask me to share the alpha preview of DaveCad, I can't however I can tell you that its the eagles tail

author: Unknown
author_rank: Unknown
timestamp: June 17, 2013, 05:04:08 pm
content: yes i imagine it can be replaced,how bout opening it up and getting a shot of the otherside of the enclosure?? in the meantime, i would connect it via alligator clip and continue your work. loose grounds tend to be a bad thing.

author: Unknown
author_rank: Unknown
timestamp: June 17, 2013, 05:17:00 pm
content: It's most likely a 4mm terminal, a standard connector used on PSU's and other equipment; they can be purchased individually... see URL:http://www.ebay.co.uk/sch/i.html?_odkw=4mm+banana+plugs&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0&_nkw=4mm+banana+terminals&_sacat=0Looks like your PSU terminal has a direct chassis bolt-on ? wont know until you open it for a closer look; either way, you should be able to retro-fit a replacement 4mm terminal.The plug in day's gone-by, had a spring wire running along the shaft length, this ensured a firm fit and good electrical connection; today I see a lot of plugs with a round spring flared tube, that rotates around the plug shaft... that's okay if used for low frequency signals, but on PSU units drawing current, they produce intermittent voltage readings... my answer to this, it to solder the shoulder tip end of the plug shaft, to the round spring end of the tube.

author: Unknown
author_rank: Unknown
timestamp: June 17, 2013, 05:21:49 pm
content: in addition if your replacing one, might want to consider all of them with some good ones, like mentioned before and or a hole for direct wires. still need a picture to be sure though i saw some decent looking gold connectors listed at the link above.
Brown bag competition - Page 1
Forum section: electronics / beginners

author: ryantran
author_rank: Newbie
timestamp: March 08, 2014, 12:44:20 am
content: I am about to participate in the Brown Bag competition held in Rowan University this April and this is my first timeCan anyone tell me, what's in the competition and what should i prepare for the competition?

author: Psi
author_rank: Super Contributor
timestamp: March 08, 2014, 12:57:44 am
content: Quote

author: captainscarlet
author_rank: Contributor
timestamp: March 08, 2014, 02:05:26 pm
content: Will there be electronic components in the bag?I entered once and got a bag of paper clips, rubber bands and string.

author: rollatorwieltje
author_rank: Unknown
timestamp: March 08, 2014, 02:33:20 pm
content: Quote
Brushed AC Motor Reversal - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: July 29, 2018, 11:21:58 pm
content: Pretty sure I need to change the relationship between the armature and field to reverse this motor.Just need a second opinion on this.

author: tecman
author_rank: Frequent Contributor
timestamp: July 30, 2018, 12:02:49 am
content: Yes, reversing the brush leads will reverse the motor. However if you notice that the brushes are offset from the magnetic poles. This will result in lower performance and more arcing at the brushes. You would need to offset the brushes to the opposite side of the poles to equal performance.paul

author: Jwillis
author_rank: Super Contributor
timestamp: July 30, 2018, 12:42:58 am
content: OK cool.I could just disassemble the brush board and flip it over to change the brush angle if to much arcing is present.It's an old sewing machine motor with a foot control box.I'm using it to run a coil winder so I don't have to use the crank.I'll post what I did so others can use the information if they need it.
Brushed Reversible DC motor controller with encoder input - Page 1
Forum section: electronics / beginners

author: Veketti
author_rank: Regular Contributor
timestamp: May 29, 2025, 06:34:58 pm
content: Dear All,I've got 12VDC geared brushedmotorwhich has integrated hall sensor and I'm trying to find ready made reversible variable speed controller to it. All the controllers that I've found so far are for brushless motors or doesn't have encoder input. Is it really so that such thing for this motor doesn't exist? Ideal would be controller which doesn't have separate direction switch, rather than dial/pot which turning either direction controls the direction and speed. Maybe I'm not just using correct keywords in searching.Thank you in advance.

author: reodor
author_rank: Contributor
timestamp: May 30, 2025, 05:57:19 am
content: What you are trying to make, is a servo. Did you try searching for a servo controller?

author: jwet
author_rank: Frequent Contributor
timestamp: May 30, 2025, 05:56:26 pm
content: Its likely that the hall effect output is used as an RPM pickup for the motor and isn't directly used.The standard chinese BDC variable motor driver will drive it fine. The hall output would allow you to measure RPM, etc or to wrap a fancier closed loop controller around it. As the last poster said, this is a servo and one with a hall would be a speed controller servo. Its not a standard off the shelf part to have a closed loop controller. You can use the motor open loop and just ignore the hall.

author: MariuszD
author_rank: Regular Contributor
timestamp: May 30, 2025, 08:53:28 pm
content: Search for dc motor controllers with feedbackhttps://www.pololu.com/category/95/pololu-jrk-motor-controllers-with-feedback

author: Veketti
author_rank: Regular Contributor
timestamp: May 31, 2025, 07:59:20 am
content: That Pololu controller seems to be closest match. However it only has one tach input when the motor has dual to know also direction, but I guess it's ok. From the Pololu material, it was not clear that with analog input is it possible to get both directions with potentiometer with center detent. Like center is off, right turn CW and left turn CCW? I ended up ordering the Jrk G2 21v3 model.Thanks once again guys. I knew I could get help from here.I need the motor feedback to get as accurate movement as possible. This motor is spinning a leadscrew which is moving camera head to get correct focal distance for focus.
brushless motor driver - Page 1
Forum section: electronics / beginners

author: david69
author_rank: Regular Contributor
timestamp: May 23, 2016, 11:34:56 am
content: Hello, Can I ask about these drivers from Ebayhttp://www.ebay.com/itm/DC-12V-24V-36V-500W-Brushless-Motor-Controller-Hall-Balanced-Car-Driver-oard/181743060992?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36144%26meid%3D75fb48ff1d094af8aadb676f718ee64e%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D271747660399JYQD brushless motor driverAre there any possibilietes to change soft start after enable?Change time of acceleration after enable, many thanksfor answer David

author: Chris Mr
author_rank: Regular Contributor
timestamp: May 24, 2016, 09:33:44 am
content: Completely useless answer I know but...You could always ask the seller!

author: david69
author_rank: Regular Contributor
timestamp: May 24, 2016, 04:40:38 pm
content: a good idea, but seller doesn`t know it
Brushless Motor Efficiency Question - Page 1
Forum section: electronics / beginners

author: mribble
author_rank: Regular Contributor
timestamp: June 10, 2019, 05:45:09 pm
content: I have all the electronics to this figured out, but I am running into some strangeness with the brushless motor I've picked. This topic is more about the actual motor efficiency than any electronics so you only need to keep reading if that interests you.I'm using the TEC3650 brushless motor. Datasheet here:http://www.ttmotor.com/productshow.php?sid=211&id=117I measured the No-load and Stall conditions with my motor and they matched the datasheet. With the device I want to spin attached to the motor it had 1400 RPMs and 3A. I don't have a good way to measure torque of my system. I think I could calculate it from the graph on the bottom of the datasheet, but the x axis isn't labeled because it is combining many different x axis units. 3A seems to be above the continuous run mode and I want to support continuous run mode. So I think I need to pick a bigger motor (they have a TEC4260 that would probably work), but I'm a little confused why this motor seems so inefficient. Previously I was using a brushed DC motor at the same 12V it was using about 0.8 A instead of the 3A of this brushless motor. That said there are many things I like about this brushless motor more (quieter and longer life) so I want to keep using a motor like this, but hopefully find one that is more efficient for my use case.Can anyone explain why this motor seems to be so inefficient at my use case and give me some pointers or websites to read that will help me pick a better motor?Thanks in advance for any tips or advice you can give!
Brushless motor torque - Page 1
Forum section: electronics / beginners

author: Saull
author_rank: Contributor
timestamp: March 17, 2017, 04:11:27 pm
content: Hi,I cant finde rating on torque for brushless outrunner motor. I am not interested in exact number but something that I can roughly estimate what motor I need. So what torque can I expect from 100 watt 1000 kv outrunner ?Thanks.

author: Benta
author_rank: Super Contributor
timestamp: March 17, 2017, 04:53:58 pm
content: The relationship is:Torque = Power / Angular frequencyThe angular frequency is 2 * pi * rpm / 60 (you need revs per second)If you run your motor at 6 V, it will rotate at 6000 rpmSo Torque is 100 W / ( 2 * pi * 100 ) = 0.159 Nm

author: W9GFO
author_rank: Regular Contributor
timestamp: March 17, 2017, 05:04:02 pm
content: If you know the power and rpm, you can calculate torque.Torque (Nm) = Power (W) / (Speed (RPM)/9.5488)A 1,000 kV motor running at 10V would be turning 10,000 rpm.100W / (10,000 rpm / 9.5488) = 0.95 Nm

author: tatus1969
author_rank: Super Contributor
timestamp: March 19, 2017, 07:44:52 pm
content: Quote from: Benta on March 17, 2017, 04:53:58 pm+1, W9GFO's formula is also correct but the result seems to have a typo.On the other hand, torque is (in a wide range) proportional with current. The 1000kV / 6V motor will happily deliver twice that 0.159Nm if loaded correspondingly, and draw (more than) twice current from the battery. Of course it can only do this for a short period and heat up quickly. Therefore I tend to look more at wattage and required rpm. Depends on the application of course. Also keep in mind that the numbers of typical BLDCs are often peak power, they often cannot deliver this continuously.

author: Benta
author_rank: Super Contributor
timestamp: March 19, 2017, 08:00:36 pm
content: QuoteNo typo, W9GFO is just calculating at a different rpm. Both results are correct.

author: tatus1969
author_rank: Super Contributor
timestamp: March 19, 2017, 08:18:02 pm
content: Quote from: Benta on March 19, 2017, 08:00:36 pm100W / (10,000 rpm / 9.5488) = 0.095 Nm

author: Benta
author_rank: Super Contributor
timestamp: March 19, 2017, 08:29:29 pm
content: Man! Missed the decimal error. You're right, of course.

author: Saull
author_rank: Contributor
timestamp: March 24, 2017, 06:57:51 pm
content: Hi,Thanks all for help, like I said I need ballpark number so those equations will help.
[moved]Brushless servomotor drive selection and control - Page 1
Forum section: electronics / beginners

author: mjkuwp
author_rank: Unknown
timestamp: December 10, 2016, 01:06:10 pm
content: sorry! accidentally had started this in the wrong forum - link directs to the correct placehttps://www.eevblog.com/forum/projects/brushless-servomotor-drive-selection-and-contr/
Bryman 786 continuity test feels slow - Page 1
Forum section: electronics / beginners

author: Gedc
author_rank: Newbie
timestamp: May 28, 2024, 05:48:07 am
content: Hi. First post & first 'proper' meter.Been using a $15 jaycar cheapo for last 10 years. Really basic continuity and voltage testing. Still very new to the functions of the BM786 but the continuity mode feels way off.On my old digitech QM1523 it's instantaneous and i can tap it on and off and it beeps on and off. On the Bryman it feels like half a second before the numbers on the display drop to 0.0006 then it beeps and flashes. Maybe this is the new norm and i'll get used to it or have i mixed up some setting / switch ?Thanks for the helpGed

author: Gedc
author_rank: Newbie
timestamp: May 28, 2024, 05:51:06 am
content: And as a follow up for other newbies - just looked at the instructions again and it appears continuity is above the ohms setting.. Not on the diode setting like my last meter. RTFM and welcome to the forum.Thanks

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 28, 2024, 05:51:03 pm
content: What about the probes? Are those in good condition?

author: Faranight
author_rank: Unknown
timestamp: May 29, 2024, 05:36:07 am
content: I'm not sure about the half-a-second delay, but I did notice that the Bryman as well as my Fluke were somewhat slower to respond to a continuity test that one of the much older multimeters I was using. I think the old multimeter had probes directly wired to the beeper or something because you could literally hear the probe metal tips grinding against each other. The response was pretty much instantaneous, but on the more modern multimeters it takes a few moments.

author: mikerj
author_rank: Super Contributor
timestamp: May 29, 2024, 06:15:38 pm
content: That's because it is annoyingly slow (IMO), one of the negatives of the 786.
BRYMEN 037 - Page 1
Forum section: electronics / beginners

author: petebryn
author_rank: Newbie
timestamp: March 03, 2024, 10:56:36 pm
content: IS THE EEV VERSION OF THE BRYMEN 037 AVAILABLE ?

author: kevin.gibbs
author_rank: Regular Contributor
timestamp: April 08, 2024, 01:41:03 pm
content: Is the EEV some kind of unique feature?

author: m k
author_rank: Super Contributor
timestamp: April 08, 2024, 05:49:38 pm
content: Maybe some discount.Hardly autographed.

author: tooki
author_rank: Super Contributor
timestamp: April 08, 2024, 06:46:55 pm
content: Quote from: petebryn on March 03, 2024, 10:56:36 pmFirst of all DON'T YELL!Anyhow, is your question whether an EEVblog edition of the BM037 isin stock, or whether an EEVblog edition of the BM037exists? Because I see no evidence that it exists. There is an EEVblog edition of the BM036.
Brymen 235 & 820-A - Page 1
Forum section: electronics / beginners

author: Russ
author_rank: Regular Contributor
timestamp: December 22, 2017, 05:44:38 am
content: HelloIs there much difference between the Brymen 235 and the Brymen 820-A?Thanks

author: Lightages
author_rank: Unknown
timestamp: December 22, 2017, 06:00:17 am
content: There is no BM820 that I know of. There is an 820 series.

author: nicalitz
author_rank: Regular Contributor
timestamp: December 22, 2017, 02:07:04 pm
content: I assume you're referring to the Greenlee DM-820A, which I believe is just a rebranded Brymen 869. You can compare the 235 and 869 side by side onwww.tme.eu

author: Russ
author_rank: Regular Contributor
timestamp: December 22, 2017, 03:48:35 pm
content: Quote from: nicalitz on December 22, 2017, 02:07:04 pmThat is correct. Thank you.Russ

author: Lightages
author_rank: Unknown
timestamp: December 22, 2017, 08:09:05 pm
content: In that case the DM820-A is actually a Brymen BM827S. Over the BM235 you get a bar graph, 10,000 count dual display, CATIV/1000V, Crest(very fast peak detection), higher accuracy, and probably some other minor things I am missing. What you get with the BM235 is a smaller more convenient size and lower price.
Brymen 235 question - Page 1
Forum section: electronics / beginners

author: Russ
author_rank: Regular Contributor
timestamp: February 10, 2018, 03:43:56 am
content: HelloSomeone is asking me this question, through Amazon,“"When measuring the resistance of microwave magnetron between the terminals I get a reading of .2 ohms then after a few seconds it goes to zero. why?"ThanksRuss

author: mzacharias
author_rank: Frequent Contributor
timestamp: February 10, 2018, 11:43:40 am
content: Are they measuring the filament?
BRYMEN BM235 - frequency? - Page 1
Forum section: electronics / beginners

author: NEMAON
author_rank: Contributor
timestamp: April 15, 2020, 06:40:57 pm
content: Dear AllMy name is Noa, from France and i'm new to this forum.I'm a DMM lover and have a few of them. One of them is the very known BM235 from brymen (Red version). Few days ago i tried to mesure the frequency of the capacitance range of a pocket DMM with no success. I dont know if this is the result of me failing to correctly use the DMM or other kind of issue.I tried with a couple of other DMMs i own and they work just fine: see attached photo.I read somewhere that in order to mesure frequency, BM235 inputs need a zero crossing. Can this be the answer to my question?nice regards

author: Manul
author_rank: Super Contributor
timestamp: April 15, 2020, 08:13:21 pm
content: What happens if you put capacitor in series, something like 100 nF ceramic?

author: NEMAON
author_rank: Contributor
timestamp: April 16, 2020, 10:02:51 am
content: Hi,No big changes, still mesure 0Hz...

author: evava
author_rank: Regular Contributor
timestamp: April 16, 2020, 10:20:45 am
content: Try that on mV range!

author: Manul
author_rank: Super Contributor
timestamp: April 16, 2020, 11:29:51 am
content: Have you read manual about different trigger ranges? Look page 9.https://www.eevblog.com/files/BM235-Manual-EEVblog.pdf
Brymen BM235 not reading DC voltage - Page 1
Forum section: electronics / beginners

author: Sananda
author_rank: Newbie
timestamp: March 01, 2018, 06:20:38 am
content: Hi anyone, I bought a Brymen EEV blog BM235 multimeter and after a few uses the DC voltage readings stopped working. I am very new to electronics. I am a residential electrical contractor and will I use this for automotive. I can't find any information on warranty in the USA. It's still under warranty factory with Brymen. I figured I'd ask if this is something I could possibly fix myself?. I am out of the return time on Amazon. I'm grateful for any help.Thank you,Sananda

author: Brumby
author_rank: Unknown
timestamp: March 01, 2018, 08:50:38 am
content: This might sound like a silly question - but I just want to ask to clear it...The meter isn't switched over to AC volts, is it?

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 01, 2018, 05:51:38 pm
content: Whats on the meter on VDC ? does it look normal? DOes it just read about zero all the time ?

author: Sananda
author_rank: Newbie
timestamp: March 01, 2018, 08:29:52 pm
content: Oh Wow, it doesn't get more beginner than this. You're right I didn't have it selected right! I thought it was just auto select. Ha! Thanks for being so kind on this forum, that's not the usual.

author: Brumby
author_rank: Unknown
timestamp: March 02, 2018, 03:41:36 am
content: Don't worry. We've all had facepalm moments on ourselves ... we just have them in the privacy of our own workshop most of the time.The big advantage is that you will take this lesson with you - and it will bear fruit not just with multimeters ... but with much of the equipment you will come to use further down the track."Why is my scope not displaying the waveform? The timebase is right; the sensitivity is right; the trigger level and slope settings should be close and ... oh ... yeah, lets change the trigger source to channel 1"

author: IanB
author_rank: Super Contributor
timestamp: March 02, 2018, 04:06:29 am
content: Also, do remember the far left setting on the dial, which really is "auto-selecting"

author: jeroen79
author_rank: Frequent Contributor
timestamp: March 02, 2018, 12:41:35 pm
content: And you left the channel mute on after adjusting the trace's baseline.
Brymen BM257s low diode voltage drop readings. - Page 1
Forum section: electronics / beginners

author: belzrebuth
author_rank: Frequent Contributor
timestamp: December 13, 2016, 05:29:45 pm
content: I noticed today that my 257s is reading lower voltage drop values compared to my UNI-T UT61E and a cheap transistor tester.For example for the same diode the brymen reads 0.459v while the uni-t reads 0.517v and the tester 0.592vI measured the test voltage of the Brymen and it is about 1.57V while on the manual it states that it should be about 1.8V.The UT61E's diode test voltage is about 2.84V.I replaced the batteries on the Brymen just in case but no change..Is there something wrong with my unit or that's normal?!I'm mostly worried about the lower than stated diode test voltage not the readings per se because if I connect the two meters in parallel to the diode I get almost the same reading.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 13, 2016, 05:36:48 pm
content: In diode test there is usually a predefined current to test the diode. That current can be different between meters. Having something like 58 mV lower voltage reading suggests the current is lower by a factor of about 10. This is easy to measure with an other meter. The open circuit voltage is not that important - it only give a maximum value and might be interesting if you want to test LEDs. With only 1.6 V, yellow LEDs might not conduct very much.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: December 13, 2016, 05:45:45 pm
content: It's not important that Brymen states as open circuit voltage about 1.8vdc typically and I get 1.57v ?Test current for the brymen is stated at 0.56mA but I can't find any info about this on the UT61E manual.EDIT:I tested one meter at a time in diode mode and the other in current mode with the black lead attached to the cathode of the diode and the red via the other meters' mA jacks and I got the following.(I used identical pairs of bananas to mini-grabbers as test leads.)BRYMEN 0.345mA 0.460vUNI-T 1.42mA 0.517v

author: Kleinstein
author_rank: Super Contributor
timestamp: December 13, 2016, 06:08:05 pm
content: The difference in current is smaller than I expected. The more usual value is 1 mA . So the Brymen is one the low side, and the UNI-T on the high side.The rather low voltage, when open circuit could be a sign that the batteries are not that good any more.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: December 13, 2016, 06:22:48 pm
content: Batteries were my first thought too so I replaced them with new anyways.Maybe I could try different batteries.I used Energizer, I could try Duracell but I think that with new batteries initial voltage differences are very subtle.
Brymen Bm357s review - Page 1
Forum section: electronics / beginners

author: Mohammad123
author_rank: Newbie
timestamp: May 06, 2024, 05:48:13 pm
content: Hello guys if anyone have this Brymen bm357 meter if he/she can give me feedback about it's performance (the resolution of Power factor,can it measure smps PF,and is it good for negative power factor measurement).
Brymen BM786 diplaying minus voltage - Page 1
Forum section: electronics / beginners

author: bach911
author_rank: Newbie
timestamp: May 26, 2024, 04:31:22 pm
content: My Brymen BM786 does not display a negative sign for negative voltages. It show the correct but positive number. Is there anyway to correct this?

author: BillyO
author_rank: Super Contributor
timestamp: May 26, 2024, 07:55:30 pm
content: It could be the zebra strip. Was you 786 ever taken apart?

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 26, 2024, 08:20:46 pm
content: Please check if you have selected the correct mode.
BSIDE ERS2 - Page 1
Forum section: electronics / beginners

author: jagmkx
author_rank: Newbie
timestamp: April 09, 2023, 09:17:00 pm
content: Sorry my previous post on this was vague. I'm trying to test some caps on the PCB board of an Onkyo NX SR626 Receiver/ Amp. This is the HDMI board and the first failure point for loss of Signal(s) Out. It is typically either the DTS chip or slightly more often and fortunate, one of the 8 caps: one larger M3P 470SP 6v, or one or more of the seven : MT 220 4v, M2 100 6v, or L4 47 16v. Board reverse has L4 47 16v and MT 220 4v (one each). I want to test each of these caps without removing them? Meters measuring electronics are not my strong house...to say the least. I can't understand how to do this with the BSIDE ERS02 Pro... thanks for the beginners lesson:)

author: Per Hansson
author_rank: Unknown
timestamp: April 10, 2023, 09:01:10 pm
content: Hello, please read the linked post in this thread, it explains how to do it:https://www.eevblog.com/forum/repair/ultra-cheap-lcr-meter-to-test-capacitors-in-circuit/msg4339462/#msg4339462

author: coromonadalix
author_rank: Super Contributor
timestamp: April 10, 2023, 11:04:41 pm
content: i would doubt theses caps are the problem(s) if the voltages lines are fine, it could be indeed the ic

author: jagmkx
author_rank: Newbie
timestamp: April 11, 2023, 03:03:44 am
content: Thanks for the replies. Sent mine back for refund and ordered a MESR 100.Had to be broken as the process path was not operating. Thanks
BSV64 transister replacement  - Page 1
Forum section: electronics / beginners

author: Jesset1996.5
author_rank: Regular Contributor
timestamp: October 28, 2016, 08:37:32 pm
content: Im currently working on a prc 320, a transister in unit 1a has went bad. this particular transister is part of the relay switching for tx. When set to tx the relays switch on and off because of this transistor. The curcuit also uses another transistor to switch the 24v upon tx so the relays dont arc. The transister in question is a bsv64 which is the transistor for the relay drive itself. Im an electronic engineering student and im new to finding transister equivalent as i usually repare tube radios and modern equipment which usually have parts readaly available. What is the best way to find a equivalent transister other than looking through datasheets? Thanks AC8WP, Jesse J Trimble

author: danadak
author_rank: Super Contributor
timestamp: October 28, 2016, 09:33:11 pm
content: Here is a place to do a cross reference.http://alltransistors.com/transistor.php?transistor=29147Or you could contact OEM of the transistor and ask them for a recommended replacement.Regards, Dana,

author: danadak
author_rank: Super Contributor
timestamp: October 28, 2016, 11:04:27 pm
content: Another way to approach this is go to digikey.com, get to the transistorselector tool, and start with package, type, NPN, PNP....and using the filtersnarrorw down key characteristics, likeVcemaxIcmaxHfeBVEceoPdissetc..Regards, Dana.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 29, 2016, 11:25:48 pm
content: Another approach is to look at some similar relay operating circuits & find out what transistors other manufacturers use.The particular application doesn't sound like it would be too critical,as long as the device has similar or better power handling & peak voltage ratings.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 30, 2016, 01:28:37 am
content: Quote from: vk6zgo on October 29, 2016, 11:25:48 pm^^^This.Transistor substitution is rarely as critical as some folks seem to believe. In this case the transistor seems to be used as a simple switch, so there can be many possible substitutes.Match:--material (silicon, germanium)--type (bipolar, mosfet, Darlington)--polarity (NPN, PNP, or Nch, Pch)--Vce, Rdson (for mosfets)--Ic--power dissipation--package and pinoutand so on.

author: P90
author_rank: Frequent Contributor
timestamp: October 30, 2016, 01:34:44 am
content: Are you looking for a transister or transistor?
BT Audio decoder  - Page 1
Forum section: electronics / beginners

author: scarr999
author_rank: Contributor
timestamp: May 15, 2024, 11:00:16 am
content: Hi All,I have purchased these items.https://www.ebay.co.uk/itm/275225937591https://www.ebay.co.uk/itm/193525989771The idea being I can put sounds on the SD card and play them to a BT speaker.I have tested the decoder with earbuds and that works OKI have connected the BT module to a BT speaker, so it connects OKWhen I add the two together using the save 5V supply and these connections in the attached picture. it seems to blow the BT board, tried two now and same result. is the audio output voltage levels too much or something?

author: CaptDon
author_rank: Super Contributor
timestamp: May 15, 2024, 12:16:55 pm
content: Two things come to mind, 1, both sides of the speaker output are hot but phase inverted. You can't ground either speaker output lead. 2, the speaker audio level is far to high for the line level or mic level that the BlueTooth board may be expecting. Since the ground of the BT board and the ground of your other board are shared you may be able to run only ONE speaker wire (choose either speaker output terminal and run that to your L Audio In or perhaps L and R Audio In. You may have to build a two resistor audio level reduction also if the BT board is over driven.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: May 15, 2024, 01:11:11 pm
content: The audio output jack would be a better choice than the speaker output terminals. The speaker amp is also a class D amplifier and completely inappropriate for the line level inputs on the BT card.

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 15, 2024, 05:48:23 pm
content: Overcurrent flow maybe. Please check the specs from the datasheets.
BT138 triac fail - Page 1
Forum section: electronics / beginners

author: cosminnci
author_rank: Regular Contributor
timestamp: February 06, 2015, 09:52:24 am
content: Hello,I have the circuit attached, with an small 220v motor, it draws 300mA. after 2 months and about 500 cycles of 40 sec one of the BT138 started to fail ( the channel started to go on like a flicker, when I put a light bulb on it flashes from slow to faster).control is done from a microcontroller.I read it might be a snubber problem, but this one works for 2 months or so..and the bad part is that when it fails it stays on and the motor runs forever and the microcontroller doesn`t sense that and can`t stop it either.regards,Cosmin

author: bdivi
author_rank: Regular Contributor
timestamp: February 06, 2015, 11:16:04 am
content: Looks like overvoltage from inductive load turn-off that gradually degraded the triac and then it finally failed.Put a RC snubber of 470R/22n across the triac and you should be fine - just make sure the resistor and capacitor ratings are suitable for 230V AC.More info here:http://www.st.com/web/en/resource/technical/document/application_note/CD00004096.pdfCheers

author: cosminnci
author_rank: Regular Contributor
timestamp: February 06, 2015, 12:33:30 pm
content: I have a kill switch on the line too. Which is the worse case, being turned off by the switch or through the optocoupler?the loads I plan to use are variable should that change the value of the snubber?could I use a snubberless triac instead or would it have the same problem ?

author: bktemp
author_rank: Super Contributor
timestamp: February 06, 2015, 12:48:47 pm
content: A snubberless triac does not solve all problems: The optocoupler is only rated for 400V, therefore you should use either a snubber or a varistor or a TVS diode to prevent it from retriggering due to the voltage spike.

author: oldway
author_rank: Super Contributor
timestamp: February 07, 2015, 09:50:42 am
content: With inductive load, snubberless triac is a good improvement because it has an higher dV/dt rating but you have to limit dV/dt on the optocoupler too.Use a RC snubber anyway.

author: Zero999
author_rank: Super Contributor
timestamp: February 07, 2015, 07:51:28 pm
content: It could be overvoltage.Add a MOV across the TRIAC or a bidirectional TVS diode between MT2 and the gate.https://www.fairchildsemi.com/datasheets/MO/MOC3052M.pdfhttp://www.onsemi.com/pub_link/Collateral/AND8012-D.PDF

author: cosminnci
author_rank: Regular Contributor
timestamp: February 10, 2015, 10:48:03 am
content: Thank you for your replies,I plan on replacing the triacs with BTA12 snubberless and add a MOVshould the mov be across the triac or across the load?SR PASSIVES VAR20-250Varistor: oxid de metal; THT; 250VAC; 320VDC; 390V; ±10%; 6,5kA; 1Wshould this one be ok ?

author: Zero999
author_rank: Super Contributor
timestamp: February 12, 2015, 08:53:22 am
content: It doesn't matter if the snubber or MOV is across the load or TRIAC but more often than not it's placed across the TRIAC for convenience.Refer to the links in my previous post for more information.
Bubble on PCB during desoldering - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: May 06, 2019, 06:43:54 am
content: Hello everyone,Sorry to make another topic so soon after my last. i was getting ready to replace a damaged component on a very old PCB, so i cleaned the solder joints i was going to desolder with a little isopropyl on a q-tip and waited about a couple hours for it to evaporate.I desoldered one pin, desoldered one on the opposite end, came back to the next pin, and right after i put my iron on two small bubbles appeared nearby on different pcb tracks...!i've desoldered many things before so i don't believe it's an issue of not knowing how to desolder, i only left the iron on only long enough to melt the solder and take it right off!does this mean the board is ruined or those tracks need to be repaired...?

author: GreyWoolfe
author_rank: Unknown
timestamp: May 06, 2019, 05:42:24 pm
content: Are you saying the pad lifted? I have heard that there is an epoxy or glue for that. If the pad is lifted only a little, it should be OK. If it is really lifted, you can end up with micro fractures. This is nothing a well done bodge wire can't fix if you want to be cautious. At any rate, the board is not ruined, it is fixable.Some years back, I got roped into replacing blown caps on ELO touchscreen monitors. They were all "refurbished", probably by a team of untrained gorillas. Cold joints, no solder at all, lifted pads, usually including lifted traces. If I remember correctly, there was only one that was so bad, I was never able to get it to work. Sometimes it took hot glue to glue the cap and bodge wires on both legs to the nearest pad to make it work again. So don't worry, easily repaired.

author: helius
author_rank: Super Contributor
timestamp: May 06, 2019, 06:29:50 pm
content: Post pictures.
Buck boost converter blowing fuses - Page 1
Forum section: electronics / beginners

author: Dunk_c
author_rank: Contributor
timestamp: October 04, 2019, 07:18:24 am
content: HiI have a small cheap regulated buck-boost DC converter that sits between my 12v solar system and a portable lithium ion battery bank. The device is used to convert the variable battery voltage to a constant 15V required by the lithium battery bank for charging.The B-B converter is portable for use in a vehicle so operates of a cigarette plug with fuse. Nearly every time I disconnect the battery bank the fuse blows presumably as the inductor coil fields collapse. This might be a big problem when used in the car. I don’t know if the battery is also experiencing a current surge but that would probably be bad! What is the fix for this? Can I stop it by inserting a couple of power diodes in series with the positive input and output lines?Cheers

author: AVGresponding
author_rank: Super Contributor
timestamp: October 04, 2019, 05:29:18 pm
content: It would help to know more, such as the fuse rating, battery pack details, solar PV details...

author: Zero999
author_rank: Super Contributor
timestamp: October 04, 2019, 07:26:07 pm
content: A simple schematic would also help.It does seem odd it's blowing the fuse when the battery is disconnected.And what's a B-B converter? Don't you mean a DC:DC converter? EDIT: Duh, Buck Boost converter.
Buck-boost converter confusion - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: August 19, 2018, 04:34:41 am
content: Hello, guysI am trying to understand the basic concept of flyback transformer.I have read that The flyback converter is based on the buck-boost converter.with the switch realized using a MOSFET and diode.Here is the picture of typical buck-boost converterNext the inductor winding is constructed using two wires, with a 1:1 turns ratio.Then It looks something like thatNext, the connections between the two windings are broken. One winding is used while the transistor Q1 conducts, while the other winding is used when diode D1 conducts.Now look at the dotted terminals of both coilsAfter changing the position of the switch the dotted terminals of coils also changes.My question is why this change happens from figure-3 to figure-4 ??I know, Unlike the ideal transformer, current does not flow simultaneously in both windings of the flybacktransformer.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 19, 2018, 06:39:30 am
content: Flip the right-hand side upside-down. It's just a polarity convention (in Fig.4).Tim

author: ocset
author_rank: Super Contributor
timestamp: August 19, 2018, 09:19:19 am
content: the familiarity with the buckboost isn't absolute...but its kind of very similar.....If you want to know hows and whys of flyback then running the LTspice sims of flyback as attached is a good way.The feedback loop equations for flyback and buckboost are very similar due to their similarities.Both the flyback and buckboost operate as "alternate shovellers"....ie, ,they shovel power in, then they shovel power out..etc etc at the switching frequency.....unlike say a full bridge which shovels power in, then rests, then shovels power in, then rests...etc etcOf course this means that the flybak and bukboost both suffer the dreaded right half plane zero

author: mikerj
author_rank: Super Contributor
timestamp: August 19, 2018, 12:51:43 pm
content: Quote from: khatus on August 19, 2018, 04:34:41 amNot just the switch! The polarity of the diode is also changed, and therefore the polarity of the output terminals.
Buck-Boost converters and the details of the inductor (field collapse) - Page 1
Forum section: electronics / beginners

author: RJSV
author_rank: Super Contributor
timestamp: May 06, 2024, 06:21:16 am
content: I've been bugged by questions about the Buck-Boost circuit that is included in the commonly seen yard or 'garden' light.Knowing the voltage is boosted by the collapse of the magnetic field wasn't enough ...it seems to be pulses coming in, as approx. 10 usec. out of every 50 (microseconds, or about a 20 khz repetition rate.)Of course I should dig out the scope, but meanwhile I'm curious about the numbers, like what is the peak voltage at the critical point in the circuit, which is what is commutated to ground, or negative common, for that 10 usec. pulse.Voltage would start at zero, as Buck-Boost switch opens, but then what ? What peak voltage would end up applied to the LED, needing some 2.8 volts to illuminate.The inductor is usually blue colored, about size of 1/2 watt resistor.

author: RJSV
author_rank: Super Contributor
timestamp: May 06, 2024, 07:11:42 am
content: Schematic shows, (I assumed 4 milli-amps) what might be some 'steady-state' or d.c. value , however, it's actually a pulse, 10 usec. connecting the coil, to ground and charging up the fieldThen, switch opening point is where things start happening but I'm not sure what form of voltage rise starts up, and what peak can be expected (for a given inductance).

author: soldar
author_rank: Super Contributor
timestamp: May 06, 2024, 10:04:57 am
content: I am not sure what you are asking. The inductance stores energy and then dumps it into the LED. If the LED is 2.8 V then that is what you will see.
Buck-Boost LED Driver - Current Sense Resistor Trimming - Page 1
Forum section: electronics / beginners

author: A.Huggy
author_rank: Contributor
timestamp: July 18, 2016, 05:07:55 pm
content: I'm working on an LED driver for a car headlight project. The target current for the LED's is 3A, but during testing, I never saw more than 2.1 amps.The LED current limit is set by a current sense resistor with a value of 0.025 ohms.Since the circuit is on a breadboard right now, I consider myself lucky the circuit works at all, and even luckier that the current is as close to the target as it is. But this got me thinking, what steps do I need to take to account for resistance in the PCB traces? Can I somehow adjust the current sense resistor after the circuit is assembled? A pot? or select the value of the resistor after I can do measurements on the actual board? Otherwise, it seems like there would be too many variables to account for to hit the target current on the money without some adjustment after assembly.Thanks for the helpSchematic:U1 is an LM3421Rcs is current limitRsense is target current

author: Signal32
author_rank: Frequent Contributor
timestamp: July 18, 2016, 05:11:01 pm
content: A schematic of what your circuit is would be useful for suggestions.But yes, you can adjust the op-amp input voltage with a potentiometer, like this:

author: Signal32
author_rank: Frequent Contributor
timestamp: July 18, 2016, 07:55:27 pm
content: Take a look at the datasheet for your IC, page 14.Also It's not recommended to make major edits to your post(adding the schematic) without posting a reply. Ppl that could have helped will not know that you change anything.

author: A.Huggy
author_rank: Contributor
timestamp: July 18, 2016, 11:48:46 pm
content: Thank you for the advice. I meant to post a reply earlier but got interrupted.I'll reread that section of the datasheet as well as the section on overcurrent protection. I guess instead of adding a pot inline with Rsns, I would add it inline with Rcsh.