hybridfree/eevblog-posts huggingface dataset:
XTAL connection question. - Page 1
Forum section: electronics / projects

author: kvresto
author_rank: Regular Contributor
timestamp: January 21, 2015, 07:22:27 am
content: Hi Everyone.Every now and again I find myself asking a question on something I would never have thought about ordinarily. This is one of those days. I’ve included 2 pics of an SMD xtal (12Mhz), each connected to my CPU in a different configuration, and my question is,.. are there any pro’s and cons on which may be the best configuration, or doesn’t it matter?Thankskv

author: okaresz
author_rank: Newbie
timestamp: January 21, 2015, 05:31:24 pm
content: In my experience it does not matter much. Of course you try to match the lengths of the XIN and XOUT traces, but I just made a mistake and forgot to do this in my recent design (see attached picture), but it works fine. At these relatively low frequencies this is not so crucial.(R55 is just a series 47R to prevent XTAL from possible overdrive). The important is to keep the crystal close to the MCU.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2015, 08:36:20 pm
content: So what's the difference?BTW, the vias are too close to the pads, and will absorb solder paste. Not really any point in using via per pad anyway, these are modest impedance, limited bandwidth traces. Length doesn't matter (as long as it's not obscenely long), grounding doesn't matter.Tim

author: okaresz
author_rank: Newbie
timestamp: January 21, 2015, 10:26:22 pm
content: I have full tenting on the vias, so solder mask covers them, they came back from reflow just fine. But yeah, if someone wants to be on the very safe side, leave a larger distance from the pads, like in kvresto's layout.

author: voja
author_rank: Contributor
timestamp: January 21, 2015, 11:29:21 pm
content: Oscillator I/Os are analog signals, so you should avoid placing them close to long digital signal tracks, as they could be inductively coupled. It is also good practice to put the ground track around the Xtal and its tracks. Some ICs even have Xtal pins surrounded by Gnd pins.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 21, 2015, 11:34:57 pm
content: As pointed out, placement orientation doesn't matter much. But you have routed signal traces in parallel to the crystal traces. Noise from that traces impairs the phase noise of the oscillator. In most applications it is not that important but if you need a "clean" oscillator it matters. Best is to surround the xtal traces with ground copper as much as possible and keep noise away from your xtal traces.Voja said the same

author: kvresto
author_rank: Regular Contributor
timestamp: January 22, 2015, 03:27:39 am
content: Thanks everyone for your good advice, much appreciated.cheers
XTAL load caps to VCC - Page 1
Forum section: electronics / projects

author: matseng
author_rank: Frequent Contributor
timestamp: January 04, 2016, 03:36:50 pm
content: I'm currently soldering up an old Z8671 on a perfboard and the XTAL pins are next to the VCC pin instead of GND as is the more commonly placement of more modern MCUs.Since it is a perfboard I don't have a nice ground plane that I just can attach the load caps to so I'm thinking of hooking them up to VCC instead of running a wire away to GND further down. From my limited theoretical knowledge I remember that a ideal voltage source should have zero resistance meaning that VCC and GND would basically be the same from the caps point of view. In practice inductances and other crap comes to play ofcourse.I have a decoupling cap put inside the 40 pin socket so hopefully that will keep the reactance between VCC/GND down a bit.Of course this is non-kosher and not a best practice, but do you think it will work? Or I'm I just making a fool of myself for even considering trying this?

author: tggzzz
author_rank: Super Contributor
timestamp: January 04, 2016, 03:52:53 pm
content: The key points are:inductance (wire = ~1nH/mm) and the voltage transients caused by changing currents in the inductor. Do the calculaton for V= Ldi/dtwhat the oscillator uses as a reference voltage for its voltage threshold. Some are a fixed fraction of Vcc-Gnd, others are a fixed voltage relative to (usually) Gndwhat clock jitter can be tolerated in your applicationYou can always suck-it-and-see, and you can always minimise problems by minimising the effects noted above. Personally I would run dedicated wires from the capacitors to the relevant Gnd pin.

author: retrolefty
author_rank: Super Contributor
timestamp: January 04, 2016, 03:59:37 pm
content: I've seen it used and said to work, I just haven't tried it myself.
XTR117 VREG 4mA limit - Page 1
Forum section: electronics / projects

author: negativ3
author_rank: Regular Contributor
timestamp: April 03, 2025, 08:07:53 am
content: Hi all,See the attached circuit which works except for one thing. The max load on the VREG pin of the XTR117 limits connected device driving. At the moment the setup draws ~7.5mA which sags the 5V REG to about 4.795V which then affects DAC output and resistor calcs.I am using it like this because it separates the mcu side from the 4-20mA loop side, allowing me to utilise a nice TFT, RTC and SDCard reader all at 3V3.One thing I've looked at are the I2C resistors as increasing those to 22k still allows 100kHz standard i2c comms, which is what i'm using. This drops those pull-ups to 0.227mA vs 1.06mA each max current when being pulled low but the DAC and Isolator still put me over 4mA budget. The DAC is actually quite good at 0.4mA by the datasheet but the isolator is of concern. Are there any 5V compliant I2C Isolator options which are very low current? Am I effectively limiting the current with my 22k pull-ups? It does state the minimum current of 0.5mA on side 2 of the isolator, so I guess I cannot see device current consumption above the I2C consumption if the device itself has any when I2C is idle!Appreciate your time.AndyEdit: R7 should read 1.25K as offset bias, not 125k.
Xtreme Electronics Lab - Page 1
Forum section: electronics / projects

author: nebulix
author_rank: Newbie
timestamp: March 31, 2014, 01:50:33 pm
content: G'Day Dave and forum members. I'm Duncan up in Canada. Absolutely love the webcasts. Didn't know there was somebody else out there into this stuff.I got my first soldering iron at age nine. I've been at it all my adult life, and moreso these days.In addition to aduinos and all the modern stuff, my specialty is refurbishing vintage tube audio. Some stuff you can see at my fledgling website herehttp://nebulix.com/xtronix/Also, my Xtreme Electronics Lab video series is under development. It will never be as clever as Dave's show, but still worth a try.My first series is entitled Vaccum Tube Boot Camp. 40s trailer here:http://nebulix.com/video/?p=28All the best and look forward to exchanging ideas with you all.Duncan McAllisterVE3DMC
XtremeUSB chip heat when idle - Page 1
Forum section: electronics / projects

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: March 15, 2014, 04:05:36 pm
content: I have this chip in a USB audio device. When the device is powered up I noticed that the external area where this chip is located was hot. The device was not in use. When I opened the device there was a heat sink on this chip, the heat sink has a gray material, like a tape, stuck on it and there was some thermal paste on the chip. The heat sink and gray tape was loosely attached. I'm going to take some temp readings and see if there's any temp difference when I connect this device to the pc with a usb cable. I'm going to look more closely at the power supply.
X/Y Rated SMT Capacitors - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 20, 2016, 09:53:06 am
content: I stand corrected, there are in fact X and Y rated SMT chip capacitors! They are understandably on the long side. Which puts them in the danger zone for PCB assembly and reliability -- large capacitors get more leverage against the electrodes, and more chance of fracturing. But anyway, here they are:http://www.digikey.com/product-search/en?FV=ffec7ee6There's also SC series from Johansen Dielectrics, and ECK series from Panasonic that are molded plastic lead frame types, bizarrely enough.The 2220 size Murata GA3 / GF are seen in the latest video (#842) with the R&S HMO1202 series teardown.I'll have to see about appnotes. In the 'scope, they are placed over slots (which is even worse for strain on the parts!), which maximizes creepage and clearance lengths (limited by package). This might not be required, but it will definitely help, especially as crud (flux, dirt, moisture ingress) trapped under the parts will really cut into reliability/safety, even if the standards don't account for situations like that (the Murata ones at least talk about IEC60950 compliance, which is often used in commercial and medical applications).In the 'scope, of course, the little board they're on is firmly mounted to a stiff chassis panel, so no board flex to worry about, and if anything they'll be even more reliable (the extra flex allowed in the board, due to the slots, will allow for differential expansion). This isn't really a strategy you can use in just any PCB though. So I don't see THT versions going away, ever, but in the odd place you can really use an SMT, it's an interesting option.Tim

author: pmbrunelle
author_rank: Regular Contributor
timestamp: January 20, 2016, 11:22:41 pm
content: Seems like it would need to be very much of a niche application...I don't see a slot below a capacitor significantly affecting the thermal stresses (small cutout in a large plane), though the slot would locally kill the bending stiffness of the board (bad).This kind of part makes me ask WHY???

author: tautech
author_rank: Super Contributor
timestamp: January 20, 2016, 11:39:55 pm
content: Quote from: pmbrunelle on January 20, 2016, 11:22:41 pmThe obvious (to me) would be properly designed walwarts and the like where compactness is paramount.
XYM Microcomputer (6502) North Sydney TAFE - seeking Information - Page 1
Forum section: electronics / projects

author: xjordanx
author_rank: Contributor
timestamp: April 29, 2023, 12:55:52 am
content: Hi Everyone,Before I went to USQ, I did my Associate Diploma at North Sydney TAFE, where some legendary teachers (Brian Webster, John Beckett, Dennis Fox, David Bowskill et. Al.) had designed and built their own 6502 based systems for teaching us about microcomputer architecture, design and programming.When I started there in 1992, they were still using a 6502 based single board computer, named "XYM" (an homage to the KIM series which were horrendously expensive in Oz in the 70s and 80s). Along with it, they had a DOS program that was a neat combination of Text Editor, VT220 Terminal Emulator, 6502 Assembler and Debugger called "XED".I am glad I kept my "WYM" 65C02 student board from the second class, as well as the study guides - they contain the full schematics and user guide for XYM and XED, and the full source code for the "WYMSTART" ROM monitor on the Student board (WYM).What they DIDN'T include was the XYM ROM monitor source code (it included several things not available in the WYM Student code). And I cannot locate the XED.exe development software for DOS.If anyone here (I'm certain there are a few) who also studied EE at North Sydney TAFE (or were on staff there) and may happen to have copies of those items, or a working XYM with the EPROM, please do get in touch as I am working to reproduce the design as a matter of posterity and interest to the retro-computing community Bil Herd and I have been cultivating. I'd really, really appreciate any help, knowledge, data!Thanks,Ben J.
Xytronic 988D solder controller modification? - Page 1
Forum section: electronics / projects

author: wildstar87
author_rank: Newbie
timestamp: October 28, 2021, 05:55:31 pm
content: I've been mulling this over for a bit. I have a Xytronic 988D, which is a decent station, but I'd like to mod it, to basically use either a Unisolder, or KSGER or similar controller.I want to be able to use either the Hakko T12, or JBC 210/245 handles, so I can use quickly swappable tips, and possibly use a desoldering gun from ZD-915, or the original Xytronic DIA-60 that is already on station. The soldering iron side seems basically the same as the Hakko 907/Clones, though I'm not sure if the pinout and thermocouple are the same.The soldering iron side seems straightforward enough, it's more the desoldering side that I'm having a harder time figuring out how to implement. Since it already has transformers, and vacuum pump built into it, I thought modifying 988D would be a good upgrade of the station.Basically I'm trying to find out if the Unisolder or KSGER/Quicko will support, or can be modified to support the desoldering gun/handle. I know the Unisolder is supposed to be able to support two handles, but it's hard to find information on this, and crawling an almost 400 page thread to find this info has been difficult. The main sticking point that I can see, is setting up desoldering side for temp measurment/adjustment, since there is little information on desoldering handle calibration/requirements. The vacuum switch trigger is simple, I can just leave that connection to the original controller. I know for the KSGER type, I would have to get two controllers, one for the soldering and one for the desoldering side, but again the same issues with that.It would also be great for it to be able to be used with the original handles as well.Any help/suggestions would be greatly appreciated. Thanks!If there is some other sub-forum that this would better be posted to, let me know as well.
Y2 capacitors downstream of common mode choke in offline SMPS - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: July 29, 2018, 03:03:49 pm
content: Hello,We have seen a report detailing that Y capacitors in an offline SMPS should be placed upstream of a common mode choke. (as in the attached schematic)However, I always thought that it was better if they were downstream of it. If one only has two Y capacitors, then surely they should best be placed downstream of the Common mode choke, as in page 4 of the following….Do you agree?Page 4 shows Y capacitors downstream of common mode choke…http://www.ti.com/lit/ug/sluu263c/sluu263c.pdf

author: floobydust
author_rank: Super Contributor
timestamp: July 29, 2018, 08:41:42 pm
content: It depends on which direction the EMI is going, through a filter.To attenuate mains EMI from entering a piece of equipment, Y caps after CM choke.To attenuate SMPS EMI from leaving a piece of equipment, Y caps before CM choke.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 30, 2018, 12:24:21 am
content: Generalizations are utterly meaningless in EMC. All that can be analyzed is each special case.Try it both ways and see which one works best. During layout, place both footprints.Tim

author: ocset
author_rank: Super Contributor
timestamp: July 30, 2018, 05:06:52 am
content: Quoteso to pass an emc test we need them upstream..to pass an immunity test we need them downstreamwould you agree?
DIY Segway - Page 1
Forum section: electronics / projects

author: El_Zog
author_rank: Newbie
timestamp: August 23, 2011, 09:11:21 am
content: a

author: bearman
author_rank: Regular Contributor
timestamp: August 23, 2011, 12:10:10 pm
content: Great work. I am impressed. Both with your project and your english.Congrats on completing your education.B

author: saturation
author_rank: Super Contributor
timestamp: August 23, 2011, 12:24:46 pm
content: Good job! It took Kamen years of research to come up with the Segway, and could do it on your own is great. Its hard to believe it 10 years old now, and his walking wheelchair is still not in the market.I'm impressed that Segway is still not as popular as it could be, its probably so way ahead of its time. It reminds me of when the car first came out.http://en.wikipedia.org/wiki/Segway_PT

author: almoehi
author_rank: Contributor
timestamp: August 23, 2011, 01:43:51 pm
content: Hi Hugo,well done. I especially like the electronics part.I was planning on starting something equal in the near future. As I don't have access to a workshop to do the mechanical stuff I hope I will get I done nevertheless.Cherrs,Armin

author: Milacron
author_rank: Contributor
timestamp: August 23, 2011, 03:28:37 pm
content: Quote from: saturation on August 23, 2011, 12:24:46 pmI've used a Segway on two different occassions and loved it. But they are rather expensive and not very portable in an average car. The alternative I prefer is an electric scooter by GoPed. This is not the cheap Chinese ones like one might see, but a proper off road capable one, made in USA, with Lithium Ion models capable of a range as much as 24 miles. And yet small enough to pick up and carry in the trunk of most any car (except my Miata)The Segway has the advantage of being able to stand still of course, but the wheel base being wider than your body does make manuvering thru crowds problematic. On the GoPed, your effective width is the same as it normally would be. FWIW, GoPed also offers gasoline and propane models....but the electrics are so quiet I prefer that.

author: El_Zog
author_rank: Newbie
timestamp: August 23, 2011, 03:36:14 pm
content: Quote from: almoehi on August 23, 2011, 01:43:51 pmThanks ! Mechanics is really a pain in the ass, as you can see for me, it's quite rubbish but it works, but maybe not forever... If I fin someone with the proper workshop i'd like to make something better.

author: Milacron
author_rank: Contributor
timestamp: August 23, 2011, 04:22:02 pm
content: I don't know who was first at a DIY Segway, but this guy is the first I remember back about 2006..http://tlb.org/scooter.htmlApparently its all the safety features of a real Segway that are the hardest part to duplicate.

author: ciccio
author_rank: Frequent Contributor
timestamp: August 23, 2011, 07:28:37 pm
content: Bearman and the others are not the only ones to be impressed.Me too...Congratulations.Keep up with the good work and let us know about all the details of the project.
YABSa: Yet another bench Supply (version A) - Page 1
Forum section: electronics / projects

author: Jebnor
author_rank: Regular Contributor
timestamp: October 05, 2013, 05:41:31 am
content: I've been working on my new bench supply. I've successfully created a positive supply which has <5mVpp Noise at 12V, over a current range from 0 to 1.2A.I use no ICs. Thought anyone? Is there anything I'm missing?

author: BravoV
author_rank: Super Contributor
timestamp: October 05, 2013, 06:28:44 am
content: Not an expert, just a thought, since that D6 1N4148 diode is series with the zener forming the voltage reference, that D6 tempco is about -2.1 mV per celcius, isn't that will affect the output stability ? cmiiw

author: Jebnor
author_rank: Regular Contributor
timestamp: October 05, 2013, 06:47:35 am
content: Quote from: BravoV on October 05, 2013, 06:28:44 amOh, Probably... Everything else is temperature compensated, as far as I can tell, so why skimp on the most important part.I have a bunch of the 1N4742a's around, I could select one and adjust the current source so that it is above 12V and then use RV1 to fine tune.

author: codeboy2k
author_rank: Super Contributor
timestamp: October 05, 2013, 08:06:46 am
content: Quote from: Jebnor on October 05, 2013, 06:47:35 amI thought it was obvious... the zener's reverse biased and thus it's tempco is approx +2mv/C... the diode D6 being forward biased is approx. -2mV/C... the two tempcos cancel each other out and this stabilizes the voltage ref over temperature.

author: BravoV
author_rank: Super Contributor
timestamp: October 05, 2013, 08:10:35 am
content: Cool, thanks guys.

author: quantumvolt
author_rank: Frequent Contributor
timestamp: October 05, 2013, 10:55:41 am
content: Very nice. I like it all discrete. Matching transistors for current mirrors and diff amps is for the dedicatedQuote from: codeboy2k on October 05, 2013, 08:06:46 amThere is more to it. The tempco varies with Zener voltage. So for example to make a decent 9 V temp compensated voltage it is common to use a 7.5 V Zener and 2 small signal PN diodes in series. Here is a decent short read:http://www.techlib.com/reference/zenertempco.htm

author: Jebnor
author_rank: Regular Contributor
timestamp: October 05, 2013, 02:00:13 pm
content: Quote from: codeboy2k on October 05, 2013, 08:06:46 amTurns out I may have accidentally did something better.Quote from: quantumvolt on October 05, 2013, 10:55:41 amAnd now, to run down the zener Diode temperature compensation rabbit hole.Thank you all.

author: Jebnor
author_rank: Regular Contributor
timestamp: October 05, 2013, 02:17:23 pm
content: Probably more than you wanted to know about Zener Diodes (127pg):http://www.onsemi.com/pub_link/Collateral/HBD854-D.PDF
YADYRTC (Yet another "Do you recognise this connector") - Page 1
Forum section: electronics / projects

author: Cerebus
author_rank: Super Contributor
timestamp: August 29, 2018, 05:29:18 pm
content: Does any recognise this connector:The face is about 5mm square.The usage is as a DC supply input to Nikon digital cameras. Perhaps it's a proprietary part, perhaps it's a generic commercial part. I have a very occasional need to power one of my cameras for a long time and I'd rather opt for wiring a suitable connector up to a bench power supply than have yet another single use power supply cluttering up the desk drawer that has become home to the collection of these in my household.
Yaesu FT-221 repeater shift - Page 1
Forum section: electronics / projects

author: christopher iles
author_rank: Regular Contributor
timestamp: June 14, 2014, 04:43:08 pm
content: Hello,Has anyone done a repeater shift mod on one of these radios? I have one and would like to have the repeater offset facility. I also intend to install a ctcss board to inject the sub-audible tone into the modulator.I want to do the repeater mod for UK repeaters.Thanks in advance,Chris.P.S. If anyone has a mutek front end for this rig for sale, I'd be interested.

author: Fank1
author_rank: Regular Contributor
timestamp: June 14, 2014, 11:12:53 pm
content: I don't know what the shift is in the UK but:From my manualfor the 146.5 band the crystal is X210 the correct frequency would be 14.200 MHz minus the shift in KHz divided by 9for the 147 band the crystal is X211 the same formula but 14.255 MHz
YAESU  RF PIN DIODE L709CER: WHERE TO GET? - Page 1
Forum section: electronics / projects

author: g6ypk
author_rank: Newbie
timestamp: December 29, 2013, 12:35:54 am
content: Hi folks. I'm in need of 4 RF PIN diodes - type - L709CER - this to repair my Yaesu FT-7900 dual band transceiver. This is D1072 & D1073 on the main pcb and would like to keep two for spare.I have found them on the Internet, but only in reels of 1000 plus. None are to be found on ebay.Will swap wife for two diodes, and for four I will throw in mother in-law and her gerbil.Any help? Tony ( g6ypk1@yahoo.com )

author: xrunner
author_rank: Super Contributor
timestamp: December 29, 2013, 12:55:29 am
content: I take it you tried calling Yaesu parts dept. I've ordered from them before.

author: AG6QR
author_rank: Frequent Contributor
timestamp: December 29, 2013, 05:33:07 am
content: I don't know where to get them, but Alan, who posts as w2aew on this board, recently did a repair video of a Yaesu FT-7800, where he found those diodes were defective in the radio (they used a different part number on the 7800, but the function was the same). He replaced the diodes with the L709CER diodes used for the FT-7900, after looking at the schematic of the FT-7900 radio.As I recall from the repair video, he was able to get four of them, but I don't recall whether he mentioned his source. If it's not obvious after watching the videos, you could send him a private message.The thread about the diagnosis is here. You may want to look at Alan's YouTube channel for the follow-up where he discusses replacing the diodes.https://www.eevblog.com/forum/projects/repair-video-yaesu-ft-7800-dual-band-vhfuhf-fm-transceiver-part-1/Just for curiosity's sake, did your radio show the same symptom? Was your diagnostic process similar to his?

author: KJDS
author_rank: Super Contributor
timestamp: December 29, 2013, 10:31:08 am
content: Can you post up a schematic and a photo of the circuit? If so I'll suggest an alternative that is readily available.

author: w2aew
author_rank: Super Contributor
timestamp: December 29, 2013, 04:12:55 pm
content: FWIW, I ordered the parts directly from Yaesu.

author: The_Penguin
author_rank: Regular Contributor
timestamp: December 31, 2013, 05:46:53 pm
content: Quote from: w2aew on December 29, 2013, 04:12:55 pmIt's been a number of years now, but I've ordered direct from Yaesu as well (Cerritos CA, if I remember correctly) and had good service.
Resistors: Yageo RC2512 vs Fojan FRC2512 - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: April 18, 2025, 03:12:33 pm
content: Does anyone have any thoughts on the differences between the following two brands of cheap 1kOhm 5% 2512 100ppm resistors:Fojan FRC2512J102 TSYageo RC2512JK-071KLAlso Uni-royalI can't really spot any substantial differences between the two (moisture resistance maybe?)The Yageo is poorly stocked by LCSC and costs twice as much. I feel that I need to choose a "more Asian" brand of resistors that is better stocked for cheap/low tolerance variants.I trust Yageo, and have never heard of Fojan, but stock levels and prices suggest that they possibly sell a lot of resistors on LCSC.The Fojan says it has a rubidium oxide resistive layer (which might bemoisture sensitive). Yageo uses a "a noble metal imbedded  into a glass substrate". (what noble metal, silver? is that why sulfur tolerant resistors are a thing?). Supposedly the entire thing is hermetically sealed so the internal construction should not matter.

author: TimFox
author_rank: Super Contributor
timestamp: April 18, 2025, 04:38:50 pm
content: I assume that “sulfur tolerant” refers to the terminations, not the internal resistance layer.If a silver-alloy terminal corrodes to silver sulfide (normal “tarnish”) before installation, it becomes unsolderable.The specified “shelf life” for SMT components normally refers to how long the components can be out in the air before soldering.

author: Haenk
author_rank: Super Contributor
timestamp: April 20, 2025, 05:13:51 am
content: It's sold by LCSC, and they offer a comprehensive datasheet - I'd say that's really good enough for a standard part with your stated low specs, can't really go wrong there.Yageo is quite a huge and known company, so they can charge more than a obviously China-oriented smaller company.

author: phil from seattle
author_rank: Super Contributor
timestamp: April 20, 2025, 05:40:33 am
content: I've use Yageo and Uni-Royal brand resistors in several products built in the 1000s. Have not had any failures from them. Though, I wouldn't expect to.2512 is pretty big, what are you building that needs that size of 1K resistors? At 1K, 1W is going to take a mighty high voltage, well above it's rating.
Yagi antenna balun problem - Page 1
Forum section: electronics / projects

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: May 27, 2021, 07:39:35 am
content: Hi folks,I am making a Yagi antenna from scratch with a folded dipole.I need to make a balun to match the impedance of the almost 300ohm dipole to 50ohm transciever and to Valance the output.Since It will be a SOTA i thought I could use a piece of rg58 c/u to make a 4:1 balun.The problem Is that I cant match the piece of coax.I've made the math by hand, using a calculator but nothing.Is a 1/2lambda piece of coax but I cant match It.I am checking the S11 with a VNA that I calibrated with its ecal.Any suggestion?Edit:As load I am using a decade resistor (measured with a ESR Meter its almost non inductive nor capacitive)

author: HB9EVI
author_rank: Frequent Contributor
timestamp: May 27, 2021, 09:50:31 am
content: what frequency are we talking here?you might try the calculator for the DL6WU yagis which use folded dipols:https://vk5dj.com/yagi.html

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: May 27, 2021, 10:06:24 am
content: 144MHz

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: May 27, 2021, 12:42:03 pm
content: Quote from: HB9EVI on May 27, 2021, 09:50:31 amI've done another One.This One doesn't seen that bad no?Almost -19db on 144-146

author: HB9EVI
author_rank: Frequent Contributor
timestamp: May 27, 2021, 04:07:16 pm
content: then let us know, which one you built; I'd be interested, though I avoid folded dipoles on VHF for my projects

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: May 27, 2021, 06:32:48 pm
content: Quote from: HB9EVI on May 27, 2021, 04:07:16 pmPain in the cheeks to feed?
Yagi antenna with collinear as driven element? - Page 1
Forum section: electronics / projects

author: Delta
author_rank: Super Contributor
timestamp: December 29, 2015, 11:38:13 pm
content: I stumbled on this on t'internethttp://www.thingiverse.com/thing:19548As I understand it, the driven element in a Yagi is normally a dipole, but I think that these standard WiFi antennas are actually collineas. Would this work at all?I ask, as I am looking to build some simple antennas for a 2.4 GHz video link. I only need a small amount of gain and directivity, so it doesn't warrant a big 24 element Yagi from eBay (and I don't want to be directing a powerful beam at my house in case it upsets my home WiFi (even if I pick my channels carefully). I may struggle to efficiently feed a home-made Yagi given that dipoles have 72 ohm impedance, and I assume the Tx had 50 ohm output impedance. I had looked at building a cantenna, but if this bodge up can give a few dBs of gain then it will be simple, cheap and ideal.But can a collinear driving a Yagi work at all?Cheers!

author: Howardlong
author_rank: Super Contributor
timestamp: December 30, 2015, 12:02:26 am
content: Possibly but if you only want 10dBi of gain or so, you only need half a dozen elements and a decent properly made antenna designed for the job.The Cantenna, if it's the same one originally published about 15 years ago, made from a Pringles container, is bullshit, its dimensions are too small to act as waveguide at 2.4GHz, and it's questionable as to how the outer of the coax ever connected. There may be more recent designs of course.I did a ton of work on 2.4GHz antennas in about 2000-2001, shortly before the band became ubiquitously used for WiFi. I'd recommend being careful of internet claims, much of the "work" in this area has little if any fact behind it.Kent Brittain is the go to guy for this stuff, he lives and breathes it. Take a look at his PCB antennas, for example 10dBi from a PCB antennahttp://www.wa5vjb.com/pcb-pdfs/Yagi2400.pdf
Yamaha AS-701 phono input capacitance? - Page 1
Forum section: electronics / projects

author: hifinerd
author_rank: Newbie
timestamp: April 21, 2024, 06:10:16 am
content: I have a Yamaha AS-701 integrated amp (same as 801 except the DAC). Some MM phono cartridges are picky about the maximum capacitance; Audio Technica cartridges are said to work best with C at or below 200 pF. I didn't want to order the service manual just for this. Do any of you know the exact phono preamp input specifications? Thanks in advance!

author: moffy
author_rank: Super Contributor
timestamp: April 21, 2024, 07:23:18 am
content: The RCA shielded cable should be the source of most of the capacitance.

author: hifinerd
author_rank: Newbie
timestamp: April 21, 2024, 11:49:33 am
content: I have a very low capacitance set of phono interconnect leads. I was hoping someone here had a service manual and could look up the specs or look on the schematic.

author: CaptDon
author_rank: Super Contributor
timestamp: April 21, 2024, 04:08:00 pm
content: schematic download online?

author: wasedadoc
author_rank: Super Contributor
timestamp: April 21, 2024, 04:24:02 pm
content: The Service Manual is available online. Gratis from at least one source.
Yamaha PM2000 direct out help/question - Page 1
Forum section: electronics / projects

author: mkiijam
author_rank: Regular Contributor
timestamp: April 11, 2023, 05:28:14 am
content: IC 10 seems to be the best place to pull the direct out, but I have a couple of questions / issues that I need some help with.1. I've whipped up a little THAT 1646 circuit, but then realized that I need (according to the THAT applications engineer) need to allow for maximum current draw against a short to ground which is 80mA. This is a 32 channel desk, and there is NO-WAY I wanna put that extra load on the Yamaha PSU. Now, maybe realistically the added circuits would never see that kind of current draw?2. So then what about just adding another cap (470uf-ish?) and a transformer directly to the output of IC 10? Would the cap and TRX interact with the PAN control in some weird way?3. Nothing's free in waterworld. How do I know how much extra current is pulled from IC 10 to drive a transformer? Just as simple as DCR and RMS of IC 10's output?Thanks guys.
YAMAHA YST-SW80 Home Sub Woofer Do I keep blowing it through ignorance? - Page 1
Forum section: electronics / projects

author: modz786
author_rank: Regular Contributor
timestamp: November 27, 2019, 11:58:08 am
content: YAMAHA YST-SW80 Home Sub WooferHi Guys and Gals )))this sub has two choices of inputs, RCA or direct Amp input with speaker out terminals.Im wondering does it have a max amp input rating that it can handle because I cant find anywhere what the Max input watts from an Amp should be ?The output transistors keep blowingIm a newbie in the forum so can i publish a link to the schematic service manual here?Cheers!

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 27, 2019, 01:51:29 pm
content: Just replace the whole amplifier board with a fairly cheap class D module?

author: modz786
author_rank: Regular Contributor
timestamp: November 27, 2019, 04:12:03 pm
content: Class D, its a last consideration if fault not cured.The volume is reduced as it still works but doesn't sound nice.When the replacement pair of Transistors arrive I will scope the board this time
Ye Olde Cable Lacing Knot - Page 1
Forum section: electronics / projects

author: graybeard
author_rank: Frequent Contributor
timestamp: April 23, 2020, 05:48:46 am
content: In this 3 minute video I demonstrate a quick, easy, and very effective cable lacing knot. It is much quicker than many of the examples you will see and works great.It was shown to me by Scott Wood who was the Senior Engineer in the Display Electronics Department which was part of Radar Systems at the Hughes Aircraft Company when I worked there in the late 1970s.I have passed it on to many young engineers and technicians over the years and I thought you would like to know it as well.

author: Cubdriver
author_rank: Unknown
timestamp: April 23, 2020, 06:50:21 am
content: Great tip - thanks for making and posting the video. I need to get some lacing tape and try this out. I think another big advantage to lacing is that (especially for slender harnesses) it is much less bulky than tiewraps with their gripping heads. The heads of even the smallest zip ties will often be nearly as big as the cross section of the harness if it's only a few small gauge wires.-Pat

author: MarkF
author_rank: Super Contributor
timestamp: April 23, 2020, 12:48:26 pm
content: This is the knot I was taught for Navy sonar simulator cable runs(time 1:00 to 2:00 then cut. No running knot):

author: Paul Moir
author_rank: Frequent Contributor
timestamp: April 23, 2020, 03:42:44 pm
content: Another advantage is for cable management at elevated temperatures. A roll of nomex lacing tape is pretty inexpensive compared to PEEK wire ties.Is the only reason to do a running knot is that it's faster?

author: Wimberleytech
author_rank: Super Contributor
timestamp: April 23, 2020, 06:53:56 pm
content: Lol...great. In the last stage, you form a bite. If you do not pull the working end all the way through but stop part way, then tighten from the standing end, you have a "Highwayman's Hitch." A Highwayman's Hitch is a quick-release hitch so that when the sheriff is chasing you out of the saloon, you can release your horse and high-tail it out of there, lickety split!Of course...your application has no use for a quick release!!I learned just the other day that the Highwayman's Hitch is also called a Spanish Running Noose as well.I like knots...so there!

author: Wimberleytech
author_rank: Super Contributor
timestamp: April 23, 2020, 06:59:51 pm
content: Quote from: MarkF on April 23, 2020, 12:48:26 pmConstrictor knot is far better than the Clove hitch. It is as easy to tie and does not require those extra overhand knots to secure it.Nice cable management technique.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: April 23, 2020, 08:26:27 pm
content: Anyone not wanting to watch those videos can refer to NASA-STD-8739.4, chapter 9.(or IPC-WHMA-A-620C)

author: graybeard
author_rank: Frequent Contributor
timestamp: April 28, 2020, 07:55:44 pm
content: Here is a photo of the completed power supply harness I was working on in the video. Click on the image for a full resolution version.Chris
Yes ... another ESR meter. - Page 1
Forum section: electronics / projects

author: taiteki
author_rank: Contributor
timestamp: April 17, 2014, 06:22:21 pm
content: Hi! i am working in an ESR meter. I will use in circuit meter.I hope someone could help me in a cuestion.The voltage over de capacitor under test is 75 mV Vp, 150mV Vpp.In the case of an 1N5822 (Von = 0,115 V) works fine.Can i increase the voltage, or 150mV is ok?Thx! and sorry for my english.

author: w2aew
author_rank: Super Contributor
timestamp: April 17, 2014, 06:56:14 pm
content: Small mistake in your schematic? Looks like you have the op amp inputs reversed. If you're getting enough sensitivity/resolution with the small drive, then there's no reason to increase it. One difference between this design and others I've seen is that your test signal applies a bipolar signal to the capacitor, which will momentarily change the polarity on electrolytic caps. Many other designs use a unipolar squarewave drive signal so that the capacitor under test doesn't get reverse biased.

author: taiteki
author_rank: Contributor
timestamp: April 17, 2014, 08:03:44 pm
content: sorry ... fixed.Yes there are a reverse biased. I will search about that.I hope that don´t affect the capacitors.the ESR only can measure form 0,02 to 3 ohm.thx!, Fran.

author: dannyf
author_rank: Super Contributor
timestamp: April 17, 2014, 08:19:58 pm
content: QuoteThe only capacitors that are sensitive to reverse polarity are tantalum and super caps. Tantalum, even when briefly exposed to reverse (DC) polarity, can be damaged and often time go into flame / explode.
Yet Again, What is this connector?  circular 4 pin, and miniature non-threaded  - Page 1
Forum section: electronics / projects

author: LaserSteve
author_rank: Super Contributor
timestamp: April 04, 2023, 10:53:25 pm
content: On an Ophir Laser Power Meter sensor.... and readoutOphir disavows all knowledge of this older model, made before the company was sold.Thanks for any help in Advance...Searching for a good friend...Thanks,Steve

author: Benta
author_rank: Super Contributor
timestamp: April 04, 2023, 11:05:21 pm
content: Might be LEMO.

author: helius
author_rank: Super Contributor
timestamp: April 04, 2023, 11:17:27 pm
content: Quote from: Benta on April 04, 2023, 11:05:21 pmOr Fischer, or Hirose, or Souriau. A lot of these circular connectors look alike.See if there is a number or logo on the shell or the insert/insulator.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: April 05, 2023, 01:10:02 am
content: Does it have lugs for a bayonet lock? Please give dimensions!

author: htassell
author_rank: Unknown
timestamp: April 05, 2023, 02:11:15 am
content: Looks like Hirose HR10 series to me. Possibly HR10A-7P-4P would be the mating connector?https://www.digikey.com.au/en/products/detail/hirose-electric-co-ltd/HR10A-7P-4P-73/1095440

author: ajb
author_rank: Super Contributor
timestamp: April 05, 2023, 02:52:44 am
content: Looks very much like a Hirose HR10A, and the keying appears to match theHR10A-7R-4SB(73).

author: Terry Bites
author_rank: Super Contributor
timestamp: April 05, 2023, 11:36:21 pm
content: I think its HR10 series too, but check the dims.Don't say Hi rose unless you want to sound silly. He, Ro-Se!Loads of Chinese knock -off versions.
yet another clock : axial bulbs based design - Page 1
Forum section: electronics / projects

author: kelvak
author_rank: Newbie
timestamp: March 19, 2015, 07:35:06 pm
content: Hello to everyone.This is going to be my very first post so, please, forgive me for any initiation rite I probably have missed. I haven't seen any "new user presentation" topic so please allow me to do so here.I am a graduated engineer, not in the field of electronic design though. I have always had a particular interest on electricity, electronics. For nearly a decade I have been reparing various electronic devices such as hifi amps, radio cars, PSU, TV, electronics toys, radio receivers, guitar amps... But until very recently I was not into electronic design.My very first project was completed a few weeks ago, it was a small "pulse-to-DTMF" module based on atmega328 needed to make an old S63 Socotel phone work again on modern adsl "boxes".I decided to register to the EEvblog forum to share with you my second project : an axial bulbs clock, based on Atmega328 and RTC DS1307, using multiplexing (74595) and ULN2003 darlington arrays to drive the lamps. Lamps are 12V, 50mA axial 4*19mm. For now, it is still build on a prototyping board. I plan to make a real PCB manufactured so it would look a bit less "how are you doing"kelvak

author: Zero999
author_rank: Super Contributor
timestamp: March 19, 2015, 08:30:00 pm
content: Looks good.I bet it uses quite a lot of power though.

author: rdl
author_rank: Super Contributor
timestamp: March 19, 2015, 08:56:33 pm
content: I like it. It has a nice sort of "retro" look.If you find the DS1307 a bit lacking in accuracy, check out the DS3231 or others in that family.

author: kelvak
author_rank: Newbie
timestamp: March 19, 2015, 09:12:04 pm
content: Thanks!Thanks for the DS3231 advice. Actually I was a bit concerned by the accuracy at first, however I thought I would replace the crystal in case of unacceptable temporal drift. For now, I use a standard 32.768kHz "one-hung-lo" xtal which surprinsingly stick to my time reference (about 1s/day drifting which is, imho, acceptable).I would definitely go for the DS3231 in any future improvement.Concerning the power consumption, I feed it with a 9V/2A power pack, so I can limit the bulbs (12V) wearing. The clock consumes about 10-15W and has the brightness of a few candles put together : that also increase that warmy vintage look
Yet another current sink design - Page 1
Forum section: electronics / projects

author: exodia
author_rank: Contributor
timestamp: June 05, 2012, 12:23:16 pm
content: HelloI'm building a current sink which will be used to charge a big capacitor at a constant current.i'm shooting for 150 VDS@4AMosfetsi'll be using the FDA38N30 from fairchild, 4 of them so about 1A from each. The parts have a DC curve so this is not only a switching mosfet.Sense resistori'll be using 0.1 ?, that will give a voltage drop of 0.1Volt at full current, also for 1A at output i'll be needing 0.1 volts to provide to the Source and sense resistorNow come the tricky part the opampI'm thinking of using a TLV2374, The offset voltage is max 6mv, it's Rail to Rail which is more than good for my case. Now to tell you the truth i don't know what else should i pay attention for Opamp selectionThe circuit i'm gonna use i took it from a TI paper

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 05, 2012, 01:54:34 pm
content: Must be a big capacitor, what's it for?Why does it need constant current charging?I am not sure what your circuit is for, it's going to need a bit of surgery to get 150 volts out of it.By my calcs.the positive input will be 100u * 10k = 1 volt.therefore the negative input will be the same, assuming we are in the op-amp normal working range and the voltage on top of R2 will also be 1 volt.??

author: Kibi
author_rank: Unknown
timestamp: June 05, 2012, 10:31:20 pm
content: quote author=exodia link=topic=8765.msg118090#msg118090 date=1338898996]I'm thinking of using a TLV2374, The offset voltage is max 6mv, it's Rail to Rail which is more than good for my case. Now to tell you the truth i don't know what else should i pay attention for Opamp selectionThe circuit i'm gonna use i took it from a TI paperI used the TLV2374 in my design. It works fine for me.https://www.eevblog.com/forum/projects-designs-and-technical-stuff/dave's-dummy-load-with-extra-features/msg104682/#msg104682

author: exodia
author_rank: Contributor
timestamp: June 06, 2012, 11:32:26 am
content: Quote from: HackedFridgeMagnet on June 05, 2012, 01:54:34 pm

author: hlavac
author_rank: Frequent Contributor
timestamp: June 06, 2012, 11:54:50 pm
content: With cap discharged there will be 150W of power loss on each MOSFET, can they take it? Heat sinks and all?Instead of linear design maybe use one of these specialized PFC preregulator ICs? They basically do what you want (soft start), and do it with correct power factor loading on the AC input...

author: hlavac
author_rank: Frequent Contributor
timestamp: June 07, 2012, 12:26:07 am
content: As a postapo alternative solution, take an old electric 600W hot plate and connect it in series between the bridge and supercap and you are done
Yet another digispark clone! - Page 1
Forum section: electronics / projects

author: bootfetch
author_rank: Newbie
timestamp: October 11, 2013, 05:39:56 am
content: Hello,Here is my attempt in cloning Digispark - its still on the board design phase and i still need to get some funds to paypal for the fab but heres how it looks right now.I changed the layout so that it can go with most breadboards and added a little prototyping area.please leave comments on it thanks

author: matkar
author_rank: Regular Contributor
timestamp: October 11, 2013, 07:20:38 pm
content: One thing jumped into my eyes right away. I don't like those two vias in front of the D+ and D- USB connection pads. It doesn't matter if solder mask is covering them. Eventually the solder mask will wear off and you risk making data connection before power is applied to the system which could cause latchup.

author: bootfetch
author_rank: Newbie
timestamp: October 14, 2013, 01:45:39 am
content: Quote from: matkar on October 11, 2013, 07:20:38 pmGot it! Ill change that! Thanks!
Yet Another DIY JBC - Page 1
Forum section: electronics / projects

author: blueskull
author_rank: Unknown
timestamp: July 20, 2017, 09:31:06 pm
content: Being inspired by a few YouTube EE bloggers, I decide to build my own JBC T470 controller.However, I don't intend to use the same structure used by everyone else (triac controlled mains xfmr).My goal is to build a small, portable T470 controller that occupies very little space, it better not be bigger than my FX888D.So, some details of implementation must be different. Here I used a high frequency half bridge converter to regulate power.Since the bus capacitors on both sides are very low compared with the rated 250W power, the heating element effectively sees only rippling mains frequency AC, therefore PFC is not needed while PF can still be very high.Also due to the bus capacitance is very small, and the RC/LC constant is far below mains frequency (yet considerably higher than switching frequency, 200kHz), so I can still skip mains cycles to read thermocouple voltage accurately.The UI is a 2002 character SPI OLED module from Newheven and a rotary encoder with push button. Auxiliary power supply is a Traco 5V power module with very low standby power consumption.