hybridfree/eevblog-posts huggingface dataset:
Jelly bean 10 turn pot? - Page 1
Forum section: electronics / beginners

author: george graves
author_rank: Super Contributor
timestamp: January 07, 2012, 01:14:36 am
content: Any suggestions on a "jelly bean" 10 turn pot part number? Any one have a favorite?

author: blackdog
author_rank: Frequent Contributor
timestamp: January 07, 2012, 01:41:23 pm
content: Hy George,Try the Vishay 534 series, there good en stable, you can get them with 6 and 6.3mmm shaft.Link to pdf file:http://www.vishay.com/resistors-variable/list/product-57065/Kind regarts,Blackdog

author: chrome
author_rank: Regular Contributor
timestamp: January 07, 2012, 04:57:33 pm
content: What the hell is a jelly bean pot?

author: Unknown
author_rank: Unknown
timestamp: January 07, 2012, 06:15:53 pm
content: Just like any other jelly bean component: a component that's very cheap and common. The term comes from the fact that real jelly beans were sold from a big jar by the pound as opposed to individually packaged and counted, because they're so cheap. A jelly bean opamp might be something like an LM358: you can find it everywhere, it's very cheap and the specs are very mediocre.

author: IanB
author_rank: Super Contributor
timestamp: January 07, 2012, 07:51:41 pm
content: Quote from: chrome on January 07, 2012, 04:57:33 pmI guess this is a bit of an Americanism, since jelly beans are not native to the UK nor perhaps to other parts of the English speaking world (though I think they have lately been introduced to the UK as a non-indigenous species).The nearest equivalent British expression would be "common or garden", or "garden variety", denoting something common, readily found and not especially exotic or expensive.(For anyone curious, the native British jelly sweet is the jelly baby, perhaps familiar to anyone who remembers Tom Baker's Doctor...)

author: FenderBender
author_rank: Super Contributor
timestamp: January 08, 2012, 04:08:03 am
content: I think the Vishay pots have better temperature stability (ppm) but, the Bourns 3590 pots are also decent and pretty cheap (Relatively speaking).

author: Zero999
author_rank: Super Contributor
timestamp: January 08, 2012, 09:03:57 pm
content: Quote from: blackdog on January 07, 2012, 01:41:23 pmIt's not cheap though. It depends on the original poster's budget.

author: Unknown
author_rank: Unknown
timestamp: January 08, 2012, 09:17:18 pm
content: Is there any decent ten turn pot that that's really cheap? I would expect the manufacturing to be fairly expensive because of the relatively complex mechanical construction (compared to a basic single turn pot). I've seen plenty of cheap multiturn trimmers, but not pots.

author: IanB
author_rank: Super Contributor
timestamp: January 08, 2012, 09:26:50 pm
content: Quote from: alm on January 08, 2012, 09:17:18 pmHow about mechanically connecting a big knob to a multi-turn trimmer?

author: Unknown
author_rank: Unknown
timestamp: January 08, 2012, 09:29:54 pm
content: That would work, but don't expect them to survive many rotations. They're usually only designed to be adjusted maybe a hundred times, especially the cheap ones.
Jelly Bean Alternative to AD5424YRUZ-REEL7 - Page 1
Forum section: electronics / beginners

author: wikevdlar
author_rank: Newbie
timestamp: May 03, 2022, 03:52:16 pm
content: Hi,I'm new here. Hope I found the right place to ask my questions.I am currently searching for a fast DAC.I need an affordable alternative for the AD5424YRUZ-REEL7, that is always available.Basically I need a fast 8 to 12 bit DAC up to 10 MHz output Bandwidth, with a voltage supply of 3.3 V. No serial interface because I need a high frequency sinus or pulse at the output. No DDS IC because I want to be flexible, considering my output signals.Greetings

author: MasterT
author_rank: Frequent Contributor
timestamp: May 03, 2022, 05:48:45 pm
content: What about uCPU with integrated DAC? Stm32F4 series could run DAC-12 bits at 10 msps. Linearity is worse than 1LSB, check it out.

author: wikevdlar
author_rank: Newbie
timestamp: May 04, 2022, 08:46:41 am
content: Thanks you ! I will do that
Jellybean parts - Page 1
Forum section: electronics / beginners

author: ratio
author_rank: Regular Contributor
timestamp: March 25, 2017, 03:44:12 pm
content: Just a quick question: WRT jellybean parts, one mfgr is as good as the next (or at least, is supposed to be), right? A 7805 made by mfgr X will perform identically as one made by mfgr Y? If I have a handful of misc mfgr's, I don't need to keep a data sheet for each part?Thanks!

author: Yansi
author_rank: Super Contributor
timestamp: March 25, 2017, 03:54:51 pm
content: I just always say: The more parts you can hoarder into your shack, the better.I don't usually keep datasheets for such jellybean identical parts from different manufacturers, BUT when the performance is somewhat critical, then it is almost mandatory, to consult the datasheet for the exact part you have.

author: madires
author_rank: Super Contributor
timestamp: March 25, 2017, 04:05:19 pm
content: In most cases the parts are very similar in specs and performance as long as you buy them from a known distributor. Cheap parts from ebay and other unreliable sources can vary, could be (poor) counterfeits or simply fakes. I've also seen enhanced versions from unknown Chinese manufacturers.

author: retrolefty
author_rank: Super Contributor
timestamp: March 25, 2017, 05:02:30 pm
content: Quote from: ratio on March 25, 2017, 03:44:12 pmFor a hobbyist this is the most practical solution. For a pro that might have to pass on a BOM toothers then a more formal approach should be used linking formal part #s with manufactures datasheets.

author: ratio
author_rank: Regular Contributor
timestamp: March 25, 2017, 06:04:19 pm
content: Thanks everyone. That's about what I expected. Reading helps it stick in my brain, so I like to have the paper copies, but I don't really want five different data sheets for what amounts to the same part.
Jensen AN-002 document question about transfomers - Page 1
Forum section: electronics / beginners

author: Gibson486
author_rank: Frequent Contributor
timestamp: August 01, 2017, 12:19:31 pm
content: I was reading through this documenthttp://www.jensen-transformers.com/wp-content/uploads/2014/08/an002.pdfthe final section has examples of how transformers transforms impedance. I am a little confused.How to does shorting the primary show 80 ohms impedance on the secondary?Later, they show more realistic examples, but they say thatIf the load were 20k ohms, it would "look like" slightly less than 20k ohms because the open circuit transformer impedance is effectively in parallel with it.So, if the impedance is lower, the are in series...what is the cutoff that determines this?I guess it is kind of a bold statement to make with out math to back it up, unless that is I am looking at the wrong and they are not saying that.Also, since they are 1:1 transformers, wouldn't that mean that it would just see what is there since it is not transforming any impedance? Or is that only in an ideal transformer?

author: TimFox
author_rank: Super Contributor
timestamp: August 01, 2017, 09:52:23 pm
content: When you short-circuit the terminals to the actual primary winding, that is roughly equivalent to terminating an ideal transformer with the DC resistance of the primary winding.

author: Gibson486
author_rank: Frequent Contributor
timestamp: August 02, 2017, 12:41:55 pm
content: So, you are saying that if I short one end, the other end will just see the a value close to the DC resistance as the load? I do not disagree, but I am just trying to find the math or some document or explanation that backs this up. Otherwise, I feel like I am just accepting it with no validation. I thought that was an academic issue, but when I open up my text books, none of them cover this case.

author: rstofer
author_rank: Super Contributor
timestamp: August 02, 2017, 02:20:44 pm
content: There's a video that discusses the matter. It seems broken right at the end. There are others...Here's another:Google has a lot of hits...
JFET approximations (gate-Voltage) - Page 1
Forum section: electronics / beginners

author: sspj9
author_rank: Contributor
timestamp: February 03, 2016, 06:17:51 pm
content: Hi,I designed a JFET to output a constant current of 10mA for an assignment. Using 2N3819 with Vdd 20 V, we assumed that Vg is 4V, however we need to explain to why we set it to 4V. I mean we could set it to any value right and just change the resistors. Can anyone help?Thanks.

author: Simon
author_rank: Unknown
timestamp: February 03, 2016, 06:52:42 pm
content: Not sure, the other way of asking the question is explain why you chose the resistors, presumably you have cme up with a suitable compromise of resistors and Vgs

author: Gyro
author_rank: Super Contributor
timestamp: February 03, 2016, 07:21:20 pm
content: This Vishay App note might be of some help to you:http://www.vishay.com/docs/70596/70596.pdf

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 03, 2016, 10:42:40 pm
content: 2N3819 isn't a very good choice for this... in most cases, Vg would need to be forward biased.Tim

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 03, 2016, 10:52:28 pm
content: "...because it works...." ?No, I guess that answer might be ok in a physics class, but probably not in an engineering class.
JFET Noise Slope in LTSpice - Page 1
Forum section: electronics / beginners

author: tec5c
author_rank: Frequent Contributor
timestamp: June 11, 2017, 10:26:38 pm
content: Hi all,I have a SPICE model of a JFET (MPF102) which I found on the edaboard forums (model validity?), which I'll give here.MODEL MPF102 NJF (VTO=-3.061588 BETA=286.155879m LAMBDA=20m IS=10f RS=239.291052 CGD=1.542479p CGS=2.567003p PB=1.49 KF=7.905907f AF=499.953m)I am trying to understand what is defining the 1/f slope when the model is simulated for noise. AFAIK the flicker noise parameter 'EF' is what determines the slope, yet for whatever reason this parameter seems to be missing from the (/all) JFET model and I'm not sure why.Here is the setup in LTSpiceNow, normally the EF parameter is default to 1. Which I believe translates to 1 decade of frequency should see the noise voltage vary by 1 decade. However, the data from LTSpice appears to be half of that, suggesting a squared factor is missing. Though with the given parameters in the JFET model, I can not figure out how I am able to change the slope.Any help would be most appreciated.

author: daddylonglegs
author_rank: Contributor
timestamp: June 13, 2017, 01:44:06 pm
content: Page 125 of this manual:http://ecee.colorado.edu/~mathys/ecen1400/pdf/scad3.pdf... says thatKF is the Flicker noise coefficientAF is the Flicker noise exponent... and AF is set to AF=499.953m (i.e. 0.5) in your model. I would guess that the coefficient is the multiple that sets the noise baseline level and the exponent sets the variation with frequency but I don't know for sure.
JFET parameters - Page 1
Forum section: electronics / beginners

author: ocayfs
author_rank: Newbie
timestamp: April 22, 2014, 12:39:01 pm
content: Hi,i want to make a jfet common source amplifier, so i need the parameters Idss, Vgsoffand gmto calculate the biasing resistors and gain. But in the datasheet, there is a min and max value and i don't know what value to take.the jfet is a 2N3819 and this is the datasheet :http://dpnc.unige.ch/tp/elect/spec-sheets/2N3819.pdf

author: krivx
author_rank: Frequent Contributor
timestamp: April 22, 2014, 12:58:46 pm
content: This can be a problem with JFETs, neither of those parameters are particularly well controlled. Ideally your design would not have a strong dependence on device parameters so that some variation isn't a problem, but this isn't always the case.If you really need accurate values you will have to measure them. There is an article here on measuring Vgsoffhttp://www.geofex.com/article_folders/fetmatch/fetmatch.htm

author: KerryW
author_rank: Regular Contributor
timestamp: April 22, 2014, 03:18:41 pm
content: Idss and Vgsoff are easy.Connect the drain to V+ (9VDC, 12VDC, etc.)Connect the gate to GND.Connect an ammeter from the source to GND. Reading is (approx) Idss.Connect a voltmeter from the source to GND. Reading is (approx) Vgsoff.Readings are approximate because the ammeter is not quite 0 ohms and the voltmeter is not quite infinite. But they are close.

author: ocayfs
author_rank: Newbie
timestamp: April 23, 2014, 11:09:18 pm
content: Thank's a lot
Jitter question - Page 1
Forum section: electronics / beginners

author: jimon
author_rank: Regular Contributor
timestamp: January 24, 2015, 12:03:13 pm
content: Question repostfrom here(Haven't got answer there, but I'm really curious).I'm playing around with modified FE-5680b frequency standard (modified to output 60 MHz instead of 1 pps, but I've checked other internal frequencies also, 20 MHz, 30 MHz). I'm using hacked DS1054Z.So if I trigger on this 60 MHz and then scroll for couple of microseconds then the waveform start to look really jittery, is it a issue with time domain oscillator in the scope ? Or maybe it's a limitation of scope trigger circuit ? I assume frequency standard is named "standard" for a reasonAlso exactly the same happens when I play around with cheap AD9850 DDS from ebay.

author: wraper
author_rank: Unknown
timestamp: January 24, 2015, 12:22:11 pm
content: Update to the latest firmware. Dave even made a video about this.

author: jimon
author_rank: Regular Contributor
timestamp: January 24, 2015, 02:19:08 pm
content: Yep, update have fixed this issue.Thanks for the help !

author: c4757p
author_rank: Super Contributor
timestamp: January 24, 2015, 02:45:43 pm
content: Quote from: jimon on January 24, 2015, 12:03:13 pmFor what it's worth, these Rb standards actually can have fairly bad jitter, they're just super-accurate with a little bit of averaging. But it's notthatbad. I'd expect the AD9850 to have quite poor jitter performance at certain frequencies, particularly approaching the maximum (that's inherent in DDS chips running from a fixed clock, nothing wrong with the AD9850), so don't worry if you still see that.
JK flip flop model help - Page 1
Forum section: electronics / beginners

author: 3roomlab
author_rank: Frequent Contributor
timestamp: June 23, 2019, 07:31:31 am
content: some play time with JK FF triggeringthe -ve edge model looks finebut the + ve model does not follow the pulseI triggered J/K/R with binary 1 to start the "count". I am guessing there is no error there. so how do I make the +ve version count like the -ve version?(these models are from the normal 74hc lib)

author: 3roomlab
author_rank: Frequent Contributor
timestamp: June 24, 2019, 11:39:10 am
content: anybody know the cure to work the +ve edge FF ?

author: rstofer
author_rank: Super Contributor
timestamp: June 24, 2019, 07:55:42 pm
content: I see a lot of people have viewed your message and none seem to understand the problem. Neither do I!But I wonder about that ground on the Set input of the first flop in the second attachment image. I'm not sure I understand what is happening there.The way the attachments are laid out, it's not readily apparent that the .asc fill is also attached. Not much to be done about that, I suppose. Some folks might run an LTspice simulation, nobody is going to redraw a schematic.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: June 25, 2019, 08:34:27 am
content: well its just clock in 74HC107 @ node 005, 003 triggers the JKR. the output worksbut clock in 74HC109, trigger JKR, it doesnt output the same way. the output only latches high.the difference as far as I understand these are that 107 is a -ve edge and 109 is positive edge trigger
JLCPCB ordering options - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: October 30, 2022, 03:18:40 pm
content: HiI've uploaded my Gerbers from EASYEDA straight to JLCPCB and they offer two prices, one for 'PCB' and another which includes the default on 'PCB Assembly' option. Looking at the photos for the latter option, they still just look like the bare PCBs that I want. I've not specified any component purchases. They then include the setup fee and the cost of a stencil for this.I just want the PCBs.What am I missing here please ?Also, without the PCB Assembly option, the PCB cost is actually $0 plus shipping because of a monthly $8 discount. Is this for real ?Thanks.

author: fourfathom
author_rank: Super Contributor
timestamp: October 30, 2022, 05:29:23 pm
content: JLCPCB will assemble your board using their large library of components. This is quite inexpensive (relatively) but you need to design your circuit using components they stock.But you don't want them to do the assembly so just go for the PCB option. Click on one of the quote buttons and choose your fab options.And yes, their discounts are for real. Here in the USA I usually pay way more for JLCPCB shipping than for the boards. I use the cheapest shipping option when I'm not in a hurry. I wish it weren't the case that my local fab houses didn't have to charge about 20x the JLCPCB price, but that's the way it is. JLCPCB quality has been excellent for my needs -- I've had them make quite a few 2-layer and 4-layer board designs.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: October 30, 2022, 06:14:53 pm
content: Quote from: fourfathom on October 30, 2022, 05:29:23 pmThanks for the reply.PCBs now ordered.I've used them before and was very pleased with the goods.
JLCPCB - PCB edges - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: June 25, 2019, 09:39:45 pm
content: HelloI wanted to order a PCB I designed on JLCPCB, but the JLCPCB Gerbers viewer shows me a different preview as the Kicad one.I correctly defined the edges of my PCB and also an inner zone which needs to be cut out (dark green), but I don't know why, JLCPCB doesn't take it into account:Have I missed something???I have a second question.When you order a PCB on JLCPCB you can select how many "different designs" there are present. But I only can upload 1 gerbers project.Is this option not intended to allow to manufacture several different PCB projects in the same order???Thank you for your answers.

author: Mr. Scram
author_rank: Super Contributor
timestamp: June 25, 2019, 10:13:42 pm
content: You can order multiple dissimilar PCB's in one order, but you'll get charged extra. Their pricing is already very low as it stands and this probably prevents them from making a loss on the whole thing.

author: Tantalum
author_rank: Regular Contributor
timestamp: June 25, 2019, 10:49:09 pm
content: But how do I upload the different gerbers files?If I merge all the files of the different PCBs in one folder, zip it and upload it, JLCPCB doesn't give me a preview of the different PCBs, so I don't really know if it is the right way to do.

author: Bud
author_rank: Super Contributor
timestamp: June 25, 2019, 11:02:16 pm
content: Pretty sure they mean different designs on a single Gerbers set. Separated say with mouse bites.

author: hamster_nz
author_rank: Super Contributor
timestamp: June 25, 2019, 11:19:22 pm
content: I had a PCB with some internal cutouts - the preview showed it as filled in, but it came cut out as expected.

author: Tantalum
author_rank: Regular Contributor
timestamp: June 26, 2019, 08:49:38 am
content: Quote from: hamster_nz on June 25, 2019, 11:19:22 pmQuote from: Bud on June 25, 2019, 11:02:16 pmOk thank you

author: thm_w
author_rank: Super Contributor
timestamp: June 26, 2019, 11:23:12 pm
content: Quote from: Tantalum on June 25, 2019, 09:39:45 pmIf you intend to break the boards apart (not using a solder paste stencil or pick and place machine), you can just draw the outlines for each individual board. No need for mouse bites or anything.Then choose 2 designs, they will charge a bit extra, and fully route out each board for you.To me what you are showing looks like two designs. Feel free to submit it to jlcpcb as one design but they might reject it. Can let us know what happens.
Job title  - Page 1
Forum section: electronics / beginners

author: Maxwell-X
author_rank: Newbie
timestamp: October 25, 2018, 05:00:58 am
content: What do you call a person that works with electronics at the same level as an electrician would do electrical work ? and electrician has an job title named electrician so, would be electronics job title

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 25, 2018, 05:02:40 am
content: Quote from: Maxwell-X on October 25, 2018, 05:00:58 amI guess that would be "technician".

author: rstofer
author_rank: Super Contributor
timestamp: October 25, 2018, 01:31:30 pm
content: Electronics Technician or ET

author: Benta
author_rank: Super Contributor
timestamp: October 25, 2018, 03:18:14 pm
content: Quote from: rstofer on October 25, 2018, 01:31:30 pmJust make certain he doesn't want to phone home all the time, you'll get no work done.

author: bob225
author_rank: Frequent Contributor
timestamp: October 25, 2018, 04:39:11 pm
content: Electronics Technician - repairs itemsElectronics Engineer - sits in a office dreaming up ways to make the technicians job harderElectronics Design Engineer - sits in his own office looking smug, Barking ordersAfter spending thousands on a prototype that doesn't work, blames the Electronics Engineer who gets to plod through mountains of paperwork, The Electronics Technician figures out the issue in a few hours it just needs a bodge cap and wireThe Electronics Engineer tries to take the credit but fails, The Electronics Design Engineer gets a pat on the back from the CEO and a nice 10k bonus at the end of the year

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: October 27, 2018, 07:18:00 am
content: My Swiss parent company always described me, in English, as an 'Electronician', and my mech colleague as a 'Mechanician (I have heard 'mechanician used in the USA.)BT

author: Kalin
author_rank: Regular Contributor
timestamp: October 28, 2018, 12:51:05 am
content: The problem is, at least in Canada, there are many different skill and intelligence levels within the definition "electrician". Some design and implement controls and automation, Some plan and build power distribution projects, some are troubleshooting wizards, others hook up wires where they are told and bend pipe. That's the issue with titles and trying to define your scope of practice with a generic title. Just my 2¢Sent from my SM-G965W using Tapatalk
Jobs - Page 1
Forum section: electronics / beginners

author: mtc2629
author_rank: Contributor
timestamp: October 07, 2013, 01:27:02 am
content: What proper jobs are there in the electronics world

author: Dave
author_rank: Super Contributor
timestamp: October 07, 2013, 01:29:24 am
content: Making shit threads to satisfy the 5 post minimum to enter the EEVblog contest.

author: geraldjhg
author_rank: Regular Contributor
timestamp: October 14, 2013, 07:39:08 pm
content: ALL of them

author: fenclu
author_rank: Regular Contributor
timestamp: October 14, 2013, 08:40:22 pm
content: Quote from: Dave on October 07, 2013, 01:29:24 amYeah, curiosly they registered a week ago and have 6 posts, wonder what that could be about...

author: Zero999
author_rank: Super Contributor
timestamp: October 14, 2013, 08:58:37 pm
content: Quote from: mtc2629 on October 07, 2013, 01:27:02 amMaplin, RadioShack . . .

author: u271D
author_rank: Contributor
timestamp: October 14, 2013, 08:59:21 pm
content: Hey us new guys have to get our post count up some how

author: Dave
author_rank: Super Contributor
timestamp: October 14, 2013, 09:21:16 pm
content: Quote from: u271D on October 14, 2013, 08:59:21 pmIt was stated in the video that you need 5 QUALITY posts in order to enter. Posting shit questions and spamming the forum doesn't suffice. Dave will be checking the posts if you are drawn, and he will reject you if you don't meet the criteria.You can get your post count up by taking the time to read the threads on the forum and then write stuff that's actually relevant and other people find helpful. Writing useless bullshit will not get you any points.

author: JoeO
author_rank: Frequent Contributor
timestamp: October 15, 2013, 02:36:20 am
content: I can't wait until the contest is over.

author: rexxar
author_rank: Frequent Contributor
timestamp: October 15, 2013, 04:36:25 am
content: I am curious though, how do most companies work with EEs? Does your boss just say "We need a product that does X Y and Z, you have 6 months."?

author: robbag
author_rank: Contributor
timestamp: October 15, 2013, 06:33:17 am
content: Quote from: rexxar on October 15, 2013, 04:36:25 amI certainly hope the boss or company wouldn't go with that approach, that's the reason we have so many pointless devices out there. Developing an idea into a product then trying to find an application. You need to start with a 'need ' first that is based on the concept of operation then derive your requirements so you are not constrained to a particular solution enforced by the boss.
Johnson Millennium J250H by Digitech - Page 1
Forum section: electronics / beginners

author: spiritledd
author_rank: Newbie
timestamp: December 11, 2013, 01:23:53 am
content: I was wondering if anyone knows where I can get my guitar amp fixed ...it is a Johnson Millennium J250H by DigitechI live in Moscow Idaho USA ...but also willing ship it if I have to, thanks

author: donbosleymusic
author_rank: Newbie
timestamp: January 28, 2014, 01:04:47 am
content: I can repair your amp, depending on the symptoms. I know these amplifiers inside and out, and I have a video that demonstrates how to take the amp apart so that you could just send the necessary boards to me for repair, saving on the shipping costs and keeping the cost of a repair reasonable - I don't need your speakers or metal chassis to work on it. I can also walk you through what might be wrong with the amp depending on the symptoms and circumstances of how the damage occurred.Please contact me through the contact form on my website which is bosleymusic.com, and we can open a dialogue.
joining transformers - Page 1
Forum section: electronics / beginners

author: glinjik
author_rank: Regular Contributor
timestamp: March 21, 2022, 07:02:58 am
content: Hi not wanting to burn my precious transformer can someone tell me if this is correct, if I join terminal 3 and 9 and tap off 2 and 10 it should give me roughly 28v?its one transformer with 2 sets of identical windings

author: not1xor1
author_rank: Frequent Contributor
timestamp: March 21, 2022, 07:37:28 am
content: Quote from: glinjik on March 21, 2022, 07:02:58 amif there is no continuity between 3 and 9 (i.e. if they are really separated windings) just do it and measure the voltage between 2 and 10. If the phase is correct you get 28V otherwise less than 1V.
joints in ribbon cable - Page 1
Forum section: electronics / beginners

author: m4rtin
author_rank: Regular Contributor
timestamp: August 15, 2015, 01:47:07 am
content: I have a ribbon cable which has following joints and traces seem to switch side:What is the reason for those joints?

author: ataradov
author_rank: Super Contributor
timestamp: August 15, 2015, 01:56:24 am
content: It is possible that designers needed to have exposed ends on different sides of the cable and could not simply bend it over mechanically.

author: m4rtin
author_rank: Regular Contributor
timestamp: August 16, 2015, 06:53:32 pm
content: Quote from: ataradov on August 15, 2015, 01:56:24 amI see. I think you are correct. However, why aren't those traces conductive at both sides?

author: ataradov
author_rank: Super Contributor
timestamp: August 16, 2015, 07:09:21 pm
content: Why would they do that? You'd still need to have vias, but now your connectors also have exposed copper on both sides. And that's probably not what is specified in a documentation for the mating part.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 17, 2015, 01:36:50 pm
content: FYI, "ribbon cable" refers to a multi-conductor cable made from wires molded into a common (usually corrugated, so it can be cut easily) plastic insulator. What you've got there is FPC (Flexible Printed Circuit), or "flat flex", etc.Not to say you're wrong by calling it that (it does appear to be cabling, and is in the shape of a ribbon), just what the proper term is.Indeed, they could've chosen to put quite a lot more on there (including components and active circuitry!), but often this is not needed.The traces are not "conductive both sides" because the material is constructed much like ordinary PCBs are: a carrier film (made of Kapton, hence the gold color) has copper foil on both sides; is etched, drilled and plated; and sealed with a cover layer (again Kapton, but could be other kinds of solder mask).Tim
Jonard DP-140 cleaning, almost too embarrassed to ask - Page 1
Forum section: electronics / beginners

author: RichardM
author_rank: Frequent Contributor
timestamp: November 30, 2024, 12:02:46 am
content: I have both the DP-140 and larger DP-100 hand desoldering pumps. The larger DP-100 comes apart easily for cleaning but for the life of me I cannot work out how to open the DP-140. I fear I might break it. Anyone has experience with this pump? I am surely missing something simple.Cheers
Josephson Junction - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: September 01, 2018, 08:36:11 am
content: I tried to do some reading about JJ but it only confused me.1. How does it convert AC to DC and DC to AC?2. In terms of power,how efficient is this conversion?

author: exe
author_rank: Unknown
timestamp: September 01, 2018, 11:20:45 am
content: PHOOL BRIDGE RECTIFIER!11 Okay, I dunno. But wikipedia says something about "The DC Josephson effect". May be that's what people use?Are you making a DIY JJ?

author: Vtile
author_rank: Super Contributor
timestamp: September 03, 2018, 06:25:06 pm
content: Josephson Junction is a method that is used as Voltage Standard in standard labs. This is something you should ask from metrology section, theremightbe some people that actually have seen a such device is practice.

author: Tony_G
author_rank: Super Contributor
timestamp: September 03, 2018, 06:41:52 pm
content: Here is a paper on the JJA from NIST:https://nvlpubs.nist.gov/nistpubs/sp958-lide/315-318.pdfTonyG
Joule Thief from scratch - Page 1
Forum section: electronics / beginners

author: J4e8a16n
author_rank: Regular Contributor
timestamp: July 16, 2015, 03:56:34 pm
content: Hi everybody,Does the XL of the coil interfere with the DC current available from power supply throughout the coil?Can we consider the 2 coils as being in parallel even if the base coil has a resistor? It is to say for the same number of turnsthe two coils have 1/L1 + 1/L2 Henry?Does the current to the led come from the power supply, the coil or both of them?As the current goes in the coils, the flux climbs to 1.9 volt or more and discharge the current in the led whenthe transistor goes in saturation. In the first time constant, let's say there is .5 A and the led uses only 50mA,does the flux 'wait'?JP Daviau

author: J4e8a16n
author_rank: Regular Contributor
timestamp: July 17, 2015, 01:53:04 am
content: Quote from: AcHmed99 on July 16, 2015, 10:57:17 pm

author: J4e8a16n
author_rank: Regular Contributor
timestamp: July 17, 2015, 10:50:38 am
content: Thank you.
Joule Thief with Zero Voltage Depletion Tranny - Page 1
Forum section: electronics / beginners

author: Undweeber
author_rank: Regular Contributor
timestamp: August 14, 2019, 12:33:57 am
content: I’ve decided to revisit the topic of joule thief’s and while reading through some lists I’ve found some suggesting the use of zero depletion mosfets (transistors?).The explanation if I have understood correctly (tell me if I didn’t) — that depletion mosfet would be allow the joule thief circuitry to fire up at low voltages, for example my joule thief circuit required 1V to fire up but could stay on down to 0.4V, with depletion or zero volt depletion it would allow the circuit to fire up at lower voltages — HOWEVER there was some sort of disadvantage, cannot recall which one, but maybe the one where it cannot operate at higher voltages, so you’d then need two circuits with a logic switching mechanism to start the circuit with one and run it on the second one().If you can recommend one of those LED chip boost converter drivers — it needs to exceed capabilities of the simple joule thief, like automatically regulating resistance to provide constant voltage, and being able to fire up at low voltages ~0.5V and handle 2.7VGoal is to run it on supercapacitors, I just ordered a few 10F ones because my 350F was way too big.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 14, 2019, 02:59:08 am
content: Right, you can run a JFET oscillator from thermocouples (<< 1.0V). Depletion MOS may work as well. You can't really get any power from it though. Mainly because no one makes such a transistor wide enough to handle appreciable current.If we're talking batteries, it's less than pointless as the amount of energy remaining in the already-dead cell is minuscule. Ditto with supercaps; from 2.5V down to 0.7V, you've consumed fully 92% of the total energy.TEGs (including thermocouples, or Peltier modules in a thermal gradient) are somewhat useful*, and may generate low voltages in the process, for which a converter is required.You're better off using such a circuit for a bias supply, then using that to power a controller that does the heavy lifting with a conventional approach (e.g., controller IC + switching MOSFET + output diode).*Mostly if you happen to have access to a few pounds of Pu238 oxide pellets, as NASA does. RTGs are very robust and reliable power sources, if terrifically inefficient (a few percent or so). Of course, here on Earth you're better off, say, hooking up a Stirling or steam engine, or where fuel is involved, any of the usual types of combustion engine.Tim
JST connector cunfusion!  - Page 1
Forum section: electronics / beginners

author: Nikan
author_rank: Regular Contributor
timestamp: November 26, 2020, 03:58:47 am
content: Hi there,I am a little confused!I want to use two different connectors in my project.The JST PUD and the JST PA connectors.One uses the SPUD-001T-P0.5 inserts and the other one uses SPHD-001T-P0.5 inserts.I have searched for some proper dies for my crimper and found these (624 1325 3 01) from rennsteig.My question is that if I get these dies will I be able to crimp the spud as well? The manufacturer only makes these dies for the sphd and I think that it is possible to crimp both the sphd and the spud with them otherwise they would make the dies for the spud as well or am I just fantasizing here?Please clarify as I couldn't find enough information about the crimping section of these inserts.I will attach both datasheets.Ps. The datasheet calls for for two different dies, is it just to make more money or are there really differences in the crimping section of these inserts?Thank you in Advance!Best regards from Germany!

author: Nikan
author_rank: Regular Contributor
timestamp: November 26, 2020, 04:05:21 am
content: I am not able to upload the PDF, not able to upload this type of file even though it is a PDF and that should be allowed...Anyways,PA connectorhttps://asset.conrad.com/media10/add/160267/c1/-/en/001426228DS01/datenblatt-1426228-jst-buchsengehaeuse-kabel-polzahl-gesamt-6-rastermass-2-mm-pap-06v-s-1-st.pdfPUD connectorhttps://asset.conrad.com/media10/add/160267/c1/-/en/001426324DS01/datenblatt-1426324-jst-buchsengehaeuse-kabel-pud-polzahl-gesamt-8-rastermass-2-mm-pudp-08v-s-1-st.pdf

author: thm_w
author_rank: Super Contributor
timestamp: November 27, 2020, 10:37:04 pm
content: The PUD is a narrower diameter but other dimensions are the same. So it looks like it will work in that it will at least fit.Will it be an ideal crimp? no idea.The PUD official crimper is here:https://www.digikey.com/en/products/detail/jst-sales-america-inc/WC-PUD1/1989505

author: Nikan
author_rank: Regular Contributor
timestamp: December 09, 2020, 03:45:11 pm
content: Well thank you for looking it up! So I guess I'll have to get a crimper for that aswell, I cant affort a loose crimp.
JST connector for LIO - Page 1
Forum section: electronics / beginners

author: shaiss
author_rank: Contributor
timestamp: June 09, 2016, 06:40:50 pm
content: This is the JST connector of a lipo I have.Is this the male end?And is their a generic term used for these connectors? A standard pitch?I need to order male and female connectors and have a hard time finding these on ebay from China.Thank you all!

author: bson
author_rank: Unknown
timestamp: June 09, 2016, 06:45:52 pm
content: JST makes a huge number of different connectors. I'd use a caliper to measure it and then flip through their online catalog until I find it. It's a crappy flash program though, not sure why they can't just use a straightforward PDF.http://www.jst-mfg.com/product/pageview/connector_e/pageview.htmlEdit: oh, they do have PDFs, but they're useless for this since you need to know which series you're looking for.http://www.jst-mfg.com/product/series_pdf_e.php

author: Jeroen3
author_rank: Super Contributor
timestamp: June 09, 2016, 06:56:02 pm
content: I think those are SH series: (1mm pitch)http://www.farnell.com/datasheets/91630.pdfhttp://www.farnell.com/datasheets/2057212.pdf
JST-XH: intelligent way to remove connected cables - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: March 26, 2019, 09:33:23 am
content: Hi.Recently I printed a board and attached some JST-XH connector (to connect leds and stuff to the board). The problem is that, testing the boards, I have to connect-disconnect the cables many times and, unfortunately, the connection is so strong that it's very difficult to remove the cables and doing it many times puts a lot of strain both on the soldered connector and the cables attached to it.So, is there any intelligent way to do this in order not to have such problems? Since the soldered connectors come from amazon, while the cable connector comes from digikey, could it be a problem of this mismatch?Please if you have any suggestions tell me. Also if your suggestion is to change the connector types!Cheers

author: xavier60
author_rank: Super Contributor
timestamp: March 26, 2019, 11:09:38 am
content: I deal with tight connectors including flexiprint by oiling them.I use PAO compressor oil.I was going to suggest a Super Lube product but they are now dumbing down their data sheets by omitting chemical descriptions for their products.

author: zirconx
author_rank: Contributor
timestamp: March 26, 2019, 06:12:54 pm
content: They make grabs/handles/cases that go onto the connector to make it easier to remove. I've noticed some of mynicer lipo batteriescome with these already attached.https://www.ebay.com/itm/10PCS-JST-XH-Plug-Connector-Protector-Case-f-3-4-5-6-7-PIN-RC-LI-PO-Battery-Plug/172813536579
JTAG diy board for Lattice PLSI1024 - Page 1
Forum section: electronics / beginners

author: screemo
author_rank: Newbie
timestamp: January 16, 2020, 11:20:53 am
content: Hello,This is my first post, so excuse me if I sound like a complete newbie.I have a pair of old CPLD's that I need to program, one of them being a PLSI1024 from Lattice Semiconductor.My progress so far:1) Purchased one of the knockoff ispDownload cables (the HW-USBN-2A, which supports 5v devices).2) Built a small board with the 10-pin JTAG connector, PLCC-68 socket wired up on SDI/SDO/GND/VCC/TMC (also verified all connections are correct).3) Added a breakout connector on VCC/GND, so that both CPLD and (ideally) ispDownload cable could be powered at the same time.Now for the questions:1) ispDownload cable requires power from the programming board - I tried 5v/10mA (on ispVM it sees the cable on usb, but tells me that no power is found on the board side) - what voltage/amps does it require? (do I need two separate voltages to make this work?)2) There's mention of a decoupling cap in the documentation for older CPLDs, but as I understand this wouldn't prevent at least the ispDownload cable to be working.3) I might have missed the ispEN is required for the CPLD to enter programming mode ?Any pointers appreciated, as I thought it would better to ask someone here that are actually experts on electronics

author: screemo
author_rank: Newbie
timestamp: January 16, 2020, 12:33:08 pm
content: Turns out I simply didn't read hard enough.Found a great example of a DIY (ghetto ?) ressource (https://www.instructables.com/id/Ghetto-Programmable-Logic-CPLD-Development-Syste/). This shows that I do not have enough VCC / GND connected and also ispEN is required as I can read further down the docs.Also the ispDownload cable is apparently powered using 9VDC/200mA.Once I get it working, I will write my findings here - maybe it helps someone.
JTAG firmware extraction from and Insertion to PCI card. New and need help. - Page 1
Forum section: electronics / beginners

author: tomjal
author_rank: Newbie
timestamp: June 14, 2022, 03:52:47 am
content: Hi,Before I start, I need you guys to know that this is new and the first time for me to do this kind of thing, but I still need to do this anyway.Here's what I have:2x Lynx L22 PCI Audio Interface (Picture below with the 6 JTAG pinouts): 1 with bad firmware, 1 with working firmware)Altera USB Blaster 10 pins JTAG (Picture below): For the connector from board to PCSome dupont wires: to connect the 10pins to 6 pins JTAGUrJTAG software: for the firmware extraction and insertion.PSU with molex and PCIe to PCI adapter (Picture below): to power the boardAgain, please correct me if I'm wrong, I'm so new.Here's the steps I'm gonna make:1. I'm gonna power up the donor board directly using my PCI adapter and molex to the adapter.2. connect my USB Blaster 10 pins (Pinouts picture below) to the PCI 6 pins(Pinouts picture below). Also I'll put the extra pin out explanation below.3. Connect USB Blaster to PC and start UrJTAG5. Follow firmware extraction from this articlehttps://embeddedbits.org/2020-02-20-extracting-firmware-from-devices-using-jtag/6. Once I get the ROM, do the same thing to the bad PCI card but with insertion of firmware from the previous card.Pinouts from 10 to 6 pins:USB BLASTER > JTAG 6 PINSTCK GND TMSTDO VCC(TRGT) TDITMS NC TDONC NC TCKTDI GND GNDVIOI'm going to connect (obviously)TMS>TMSTDI>TDITDO>TDOTCK>TCKGND>GNDVIO>VCC (Is this one correct or should I just leave it open?)I think that's all for now. Thank you everybody!
JTAG for beginners :) - Page 1
Forum section: electronics / beginners

author: dds
author_rank: Contributor
timestamp: October 19, 2010, 07:07:07 pm
content: How do I find JTAG ports if they exist on a particular board? Should i probe points with multimeter or oscilloscope?Thanks.

author: djsb
author_rank: Super Contributor
timestamp: October 19, 2010, 07:25:43 pm
content: You could look for the data sheet for a particular device and look for the connections to the following pins# TDI (Test Data In)# TDO (Test Data Out)# TCK (Test Clock)# TMS (Test Mode Select)This should give you a good start.
JTAG Location Help - Page 1
Forum section: electronics / beginners

author: donna9
author_rank: Newbie
timestamp: September 25, 2017, 01:32:32 am
content: See attached photo for referenceI have the ZBT WG3526 router.There is no data sheet that i can find, nor is the manufacturer (ZBT) willing to help me...nice.Could one of these in the photo be the allusive pins for:# TDI (Test Data In)# TDO (Test Data Out)# TCK (Test Clock)# TMS (Test Mode Select)

author: cdev
author_rank: Super Contributor
timestamp: September 25, 2017, 04:01:19 am
content: https://wiki.openwrt.org/toh/hwdata/zbt/zbt_wg3526https://www.linux-mips.org/wiki/JTAG??

author: donna9
author_rank: Newbie
timestamp: September 27, 2017, 02:02:30 pm
content: Appreciated cdev ... i ended up spamming several more ZBT's sales engineers until one of them decided to contact their behind-the-scenes tech engineers (askign them to point me to where on this motherboard the JTAG lies since the wiki page says it has one). Besides getting back several more "go <bleep yourself" (paraphrasing) one did reply and told me the 3526 doesnt have one. So either this sales person is just being polite and blowing me off, or the wiki openwrt page (among other sites) are wrong. Since i cant know which, and it seems more likely the sales rep didn't actually ask i will just put this jtag adventure behind meSo as usual cdev thanks for your assist.

author: cdev
author_rank: Super Contributor
timestamp: September 27, 2017, 09:49:17 pm
content: Its likely either jtag or a UART (serial/console) port..Are you familiar with the Sigrok (http://sigrok.org) -compatible-cheap fx2 based logic analyzers?They are insanely cheap, some are as little as $8 on ebay..Look for "24 MHz logic analyzer"Make sure you get some probes with it.. some come with a cable and mini grabbers, some come with several cables..dupont cables, etc.

author: donna9
author_rank: Newbie
timestamp: September 27, 2017, 10:14:31 pm
content: Quote from: cdev on September 27, 2017, 09:49:17 pmHey that's very intersting! Thank you. I will grab one right now.
JTAG programmers/debuggers - I'm lost - Page 1
Forum section: electronics / beginners

author: miceuz
author_rank: Frequent Contributor
timestamp: April 03, 2014, 06:26:36 am
content: I can't really wrap my head around it - JTAG is an open protocol, yet there seems to be a multitude of JTAG programmers/debuggers advertised for specific chips.Say, there is Altera USB blaster and STLink - both of them talk JTAG, so I would expect both of them are able to program, say, NXP LPC ARM cores, but I have a suspition it is not so. Then there is an opensource one from Dangerousprototypes -http://dangerousprototypes.com/docs/Bus_Blasterwhich claims to be able to do all I want. Where is the catch?What I need is to be able to program any ARM core, maybe a CPLD and in general, be able to connect to a JTAG port on any board that has it. Is this possible or I do want too much?

author: han
author_rank: Frequent Contributor
timestamp: April 03, 2014, 06:49:47 am
content: if the money not a problem use something like XJTAGwww.xjtag.com
JTAG - Tag Connect doesn't require JTDI? - Page 1
Forum section: electronics / beginners

author: roogadget
author_rank: Contributor
timestamp: September 26, 2018, 05:54:48 am
content: http://www.tag-connect.com/tag-connect-pinout-specificationsI am using the tag-connect 6 pin and it does not use the JTDI. Can JTAG work without the JTDI input though?I can't find any resources on it

author: Jeroen3
author_rank: Super Contributor
timestamp: September 26, 2018, 07:14:10 am
content: JTAG cannot, but ARM Serial Wire Debug, Microchip ICSP, Silabs C2 or AVR ISP uses a lot less pins and often shares the JTAG pins on the chip.Minimum is 3 pins, ground, clock and data.Often its 4 pins, including Vdd sense (for logic level converters)Or 5, some chips also need RESET.

author: AndyC_772
author_rank: Super Contributor
timestamp: September 26, 2018, 07:33:05 am
content: Tag-connect is just a cable and connector; you can wire it up however you like.The pinout they're suggesting is for Microchip PIC, which uses a proprietary 6 pin debug interface that's nothing to do with JTAG.
Jump Starter power bank Blitzwolf BW-JS1 - burned IC battery charger - Page 1
Forum section: electronics / beginners

author: nessarx56
author_rank: Newbie
timestamp: June 04, 2022, 10:31:12 pm
content: Hello everyone, I'm new to the forumI have a problem with my Blitzwolf BW-JS1 starter / power bank. The device has crashed. I found a damaged 5V HT7550-1 stabilizer, but unfortunately it probably damaged the main battery charging IC, which has a short circuit on the power supply of pin 1 (GND) and 20 (VDD 5V). Unfortunately, it has no markings. It is package ssop20. Maybe someone has this device and could check the marking of this IC battery charger. I searched on google but couldn't find any matching IC.Thanks in advance and regards

author: m k
author_rank: Super Contributor
timestamp: June 13, 2022, 07:55:21 pm
content: My guess is that the chip is something very standard anyway.But since you don't need the board without the chip you can also start guessing.Package type can tell something, like bottom side and shape of pin 1 mark.