hybridfree/eevblog-posts huggingface dataset:
Quadrupole in CRT - what's its purpose and how does it work? - Page 1
Forum section: electronics / projects

author: gmayer
author_rank: Newbie
timestamp: May 12, 2024, 08:58:38 am
content: Hi there,I'm working on an oscilloscope from around the late 70s/early 80s with a Thomson CRT inside. This CRT uses quadrupoles which I've never heard of before. I understand that they are a part of the electron optics, but I couldn't find anything about how they work and affect the beam/deflection compared to a non-quadrupole tube. I can fix the scope without understanding that, but I'm just interested... Any information/hint is welcome :-) .Cheers, Max

author: Njk
author_rank: Frequent Contributor
timestamp: May 12, 2024, 09:21:05 am
content: First google hit:Using magnetic quadrupoles in cathode‐ray tubeshttps://www.tandfonline.com/doi/pdf/10.1080/15980316.2002.9651898

author: gmayer
author_rank: Newbie
timestamp: May 12, 2024, 09:53:26 am
content: Thanks! That's a good starting point even thought it's probably not magnetic in my case.P. S.I swear I did some research before posting this. I can't believe I missed that!

author: David Hess
author_rank: Super Contributor
timestamp: May 13, 2024, 06:08:38 am
content: Tektronix published general details about quadrupole lenses:https://w140.com/tekwiki/images/0/0f/Tek_forum_report_5.pdf
Qualcomm QuickCharge 3/4/5 Interface Specification - Page 1
Forum section: electronics / projects

author: horvat.kamca
author_rank: Contributor
timestamp: April 28, 2021, 08:50:38 am
content: I'm a bit curious about how QuickCharge 4 and 5 works. Unfortunately, I was not able to find quickcharge specification. The only thing I found is reference to these documents in TEA19051BTK datasheet. Qualcomm® QuickCharge™ 3.0 Interface Specification — 80-NH008-2, revision K; Qualcomm®, August 1, 2017 Qualcomm® QuickCharge™ 4 Interface Specification — 80-NH008-3, revision D; Qualcomm®, August 1, 2017Can you point me to where these documents can be obtained?

author: TimNJ
author_rank: Super Contributor
timestamp: April 28, 2021, 12:52:51 pm
content: Pretty sure these are closed source, need to sign NDAs etc. On the contrary, USB PD is all out in the open.
Qualification Test MIL-STD-810F FOR AN EQUIPMENT  - Page 1
Forum section: electronics / projects

author: rakeshm55
author_rank: Regular Contributor
timestamp: March 25, 2013, 07:34:26 am
content: Hi,I am required to conduct Vibration test , High - low temperature (storage and operating) on an equipment.For the test unit, do I need to perform ESS (Environmental Stress Screening) prior to forcing the device to undergo the above tests???For Vibration test On page 514.5 - 2 of MIL-STD-810Fwww.gd-itronix.com/upload/pdf/MIL-STD-810F.pdf1.2 (e) states the same if I am not wrong.But I could not track the clause on high or low temperature tests.But I believe we need to perform ESS before quality test because all the device will undergo ESS before deploying in the field.Am I interpreting correctly??Please help me....

author: KJDS
author_rank: Super Contributor
timestamp: March 25, 2013, 07:54:05 am
content: It's been a while since I looked at Mil std 810, but from what I remember,:-If you are going to ESS each production unit before shipment then it either needs to be done before you do you tests or you need to prepare a case for not doing it for your customer to approve. It will always be easier just to do the ESS.Storage and operating temperature, and thermal shock if applicable should be in the equipment specification.Other things I've learnt from doing these over the years.Always have at least one spare equipment. Take a lot of spare test cables, plugs sockets, wire, a soldering iron or two and schematics of everything you're testing. If you're taking some custom test equipment then take two sets if possible.Take a good book, or preferably two, especially for the temperature testing. There's usually a lot of waiting time.

author: Chris Peterson
author_rank: Newbie
timestamp: March 25, 2013, 12:41:48 pm
content: ESS is assumed to be done by the manufacturer, so it comes before all other MIL-STD-810 tests if you are the manufacturer. I teach -810 classes and this is a very common question. If you have any other questions please don't hesitate to ask.
Quality Audio Recording for Video Make 5$ Wireless lav Mic for DSLR - Page 1
Forum section: electronics / projects

author: Kedar264
author_rank: Regular Contributor
timestamp: November 29, 2017, 06:18:06 am
content: Hi EveryoneRecording quality audio for video on dslr can be tricky. If you set auto gain on significant amount of hiss noise will recorded in audio . This problem makes it essential to use high quality expensive external mic .some cheaper alternatives like 1$ lav mic on ebay are worth it but they are not wirelessSo here in this video im going to make wireless lav mic with just 5$.https://youtu.be/Esp2KAbylR8And also you can make spy bug from thishttps://youtu.be/ZBjmpc3AXVQBeyond that if you know any better solution share it here , Thanks for your time.

author: b_force
author_rank: Super Contributor
timestamp: November 29, 2017, 03:39:09 pm
content: On the FM band, lol so everyone around you can pick it up as well.I doubt if that's even allowed in EU and USA.I believe there are other little modules, maybe even with bluetooth.However, it's still not ideal, since you will hear a lot of cracking and moving noises if you move to much.What I noticed is that most youtubers don't spend any time to some simple and basic audio editing that can improve your audio an awful lot.

author: dashpuppy
author_rank: Regular Contributor
timestamp: November 30, 2017, 06:32:49 am
content: Quote from: b_force on November 29, 2017, 03:39:09 pmAgreedI personally use a external recorder and then sync the audio. FM wireless mic = noise & will pick up lots of other crap too!

author: mikerj
author_rank: Super Contributor
timestamp: November 30, 2017, 08:20:04 am
content: Quote from: Kedar264 on November 29, 2017, 06:18:06 amSomeone's been watching ElectroBOOM
Quality Bench Supply recommendation (Requirements: 48V/1A). - Page 1
Forum section: electronics / projects

author: John_ITIC
author_rank: Frequent Contributor
timestamp: November 12, 2015, 12:40:38 am
content: I'm working on debugging a large board a client sent to me. Unfortunately, the board doesn't power up because the voltage rail collapses once the board starts to draw power. It looks like the bench supply rail collapses some 18V and takes some 5ms to recover from the current spike and, by then, the board has reset. This keeps happening twice per second.I now have one of these bench supplies:http://www.circuitspecialists.com/programmable-bench-power-supply-csipps55t.htmlThe manual states "response time" but I'm not sure how to interpret the specs; there is no spec that states voltage regulation as a function of positive current step.Can anyone recommend a bench supply that handles at least 0-48V output / 5A? I'd like one with current requlation. Ideally, a good brand with quality regulation.Thanks,/John.

author: John_ITIC
author_rank: Frequent Contributor
timestamp: November 12, 2015, 02:08:00 am
content: Quote from: AcHmed99 on November 12, 2015, 12:54:21 amGood idea; I added some 3000 uF and the issue went away. The board now powers up.

author: elements
author_rank: Newbie
timestamp: November 13, 2015, 10:01:37 pm
content: Proper decoupling of the IC's should be checked
quality IEC cables for the lab? cable managment (replacement for mains outlet) - Page 1
Forum section: electronics / projects

author: sarepairman2
author_rank: Frequent Contributor
timestamp: January 31, 2016, 07:02:13 pm
content: What is a manufacturer of quality IEC cables? I am looking to redo my lab and I thought it would be nice to get some quality IEC cable. I use a mixture of random shit sourced from random sources and I would like to standardize, and use nice cable management techniques too.The thick bundles of IEC cables I have running from the outlets near the floor to equipment high up drives me nutsim thinking to make some kind of other connector (deutsch?) to IEC cable out of it, then make distribution boxes per shelf. Like make my own junction boxes on each shelf. It would make cable management easy. I don't see the need of american style outlet connectors to run my test equipment on. They are designed to be cheap for mass production and shit, not to connect the pinnacle of what man has made.Do you have connector recommendations for 120VAC mains that are low profile, and have strain relief? and are bulkhead mountable. and not too expensive. and locking.am willing to pay for thinner more expensive cables if they exist.

author: nctnico
author_rank: Super Contributor
timestamp: January 31, 2016, 09:33:08 pm
content: I have been using slotted cable trunking to keep all the cabling in check. Below a picture I took when replacing my desktop:

author: sarepairman2
author_rank: Frequent Contributor
timestamp: January 31, 2016, 10:15:49 pm
content: Interesting. However it is too clunky for me. I think I will go with deutsch connectors into custom made power strips.How about the actual cable material/manufactureing style? Insulation types, brands etc.
Quantel RamCorder - Page 1
Forum section: electronics / projects

author: topsy1
author_rank: Newbie
timestamp: September 29, 2017, 07:05:05 pm
content: Hello there,I have a working V-Series Paintbox and I'm trying to get the peripheral Ramcorder working.I am wondering if anybody here has experience with the Ramcorder and can recommend any diagnostic testing I could do? I am using standard SDI connectors and I believe everything is connected. The paintbox is able to ingest the output of the Ramcorder and control it but only garbage frames appear.Does anybody have any knowledge of the Ramcorder and what diagnostics it might have? The Paintbox has serial rs232 output so it's possible to get diagnostics out of this port. Although the Ramcorder has 2 serial ports neither seem to output anything for a terminal.All internal cards seem powered and green LED's are illuminated on each. There doesn't appear to be any superficial damage but I have only very limited electronics knowledge in order to test components.Dexters Lab, who has posted here previously about his many Quantel endeavors (and made some extraordinary progress in understanding these machines), has helped enormously in getting my Paintbox working. But we are both somewhat stumped by the Ramcorder!Any thoughts or suggestions most welcome,t
Quarter Inch Jack - Looking Fot Patent - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: March 15, 2015, 03:59:23 pm
content: I am looking for the original patent on the quarter inch jack plug, as originally used on telephone equipment. I know that the design is very old and this means that there are some difficulties in finding the document I want, it may not have been scanned.Please can someone with more experience of the patent system assist?German_EE

author: free_electron
author_rank: Super Contributor
timestamp: March 15, 2015, 05:29:42 pm
content: you mean the three or four ringed , long plug with the little 'ball' at the end ?i believe those are called bantam plugsgoogle-fu 'bantam-plug patent'http://www.google.com/patents/US4975087

author: Pjotr
author_rank: Frequent Contributor
timestamp: March 15, 2015, 05:54:26 pm
content: Quote from: free_electron on March 15, 2015, 05:29:42 pmThat file is from 1990A 1-minute Google search on "telephone jack" brought up this":https://books.google.nl/books?id=EaVSbjsaBfMC&pg=PA51&dq=telephone+jack&hl=nl&sa=X&ei=c8cFVdymBsv2Up-rg4AB&ved=0CDEQ6AEwAg#v=onepage&q=telephone%20jack&f=falseBut not the patent itself

author: Fraser
author_rank: Super Contributor
timestamp: March 15, 2015, 06:03:16 pm
content: More detail or picture needed as there are several generations of the 1/4" plug as has been stated.I have used telephony patch cables with the smaller tip connection and of course most are familiar with the more common 1/4" headphone jack.Please advise which version you are interested in.Aurora

author: calexanian
author_rank: Super Contributor
timestamp: March 15, 2015, 06:22:34 pm
content: Many of those original designs that got adsorbed by AT&T when they bought up the independent phone companies, and those of bell labs were just made directly public and were never patented as an agreement with the government. You will find lots of patents with improvements to the "phone plug and jack" as is its proper name, but most likely not find a true original patent that establishes the standard for that was in the public domain in the national phone system. Lots of interesting literature about the relationship Ma Bell had with the government and the public. Just try to find the earliest one you can. It will most likely be an "improved phone jack" type patent most likely from bell labs.

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 15, 2015, 07:00:59 pm
content: Following the history of telephone patents in the Google archives well into the mid 1800s, all the patents I found seem to take for-granted the existence of what we call the common 1/4 inch "phone plug".

author: cosmicray
author_rank: Frequent Contributor
timestamp: March 15, 2015, 11:36:18 pm
content: The photo on this page (of a 1890's Viaduct 6-line switchboard) may be showing plug of this type.http://www.telephonearchive.com/phones/switchboard-pbx/viaduct-wall-switchboard-phone.htmlI saw another picture, reportedly dated 1879, of a similar type arrangement. Unless the telegraph system used them, it would be unlikely to be much earlier.
Quarterwave microstrip directional couplers - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: January 02, 2016, 05:01:32 pm
content: Just wanted to check if I understand this process correctly, or if I've forgotten something stupid:Say we want a -20dB coupling factor, 50 ohm system impedance.So we get the even and odd impedances Z0e = 55.28 ohms and Z0o = 45.23 ohms.Obviously the electrical length of the system is a quarter wavelength, for the given PCB dielectric permittivity (will calculate later).But how do we calculate the actual widths and gap spacing of the coupler for those required impedances - are there any online tools that can calculate this (like there are various websites around for ordinary microstrip/CPWG impedance calculation?) I don't have ADS or any similar expensive software available.

author: mathias
author_rank: Regular Contributor
timestamp: January 02, 2016, 06:15:48 pm
content: Check out TXLine, it might have coupled microstrip on board.

author: KJDS
author_rank: Super Contributor
timestamp: January 02, 2016, 06:23:28 pm
content: If you want to calculate it yourself, thenhttps://fenix.tecnico.ulisboa.pt/downloadFile/3779573460329/design%20of%20coupled%20microstrip%20lines.pdfProvides all the equations you will ever need, and quite a few more that you won't. Eq 66 onwards for coupled microstrip.It's probably worth finding a copy of Sonnet Lite, if only to get the end transitions verified. It's also worth remembering that unless you do something fancy that stops the microstrip being true microstrip you won't get more than about 18dB of directivity.
Quartz clock movement  specifies CZ battery, not alkaline? - Page 1
Forum section: electronics / projects

author: rickthegeek
author_rank: Newbie
timestamp: February 09, 2021, 11:18:53 pm
content: Hi!Long time lurker, first time poster!I have a project where I am going to be placing a quartz clock module (the thing that has the battery and turns the hands around), and the module I have ordered says do not use Alkaline, it specifies the older carbon-zinc battery. The description says that alkaline (or rechargables) will damage the unit.Why is this? I've never heard of alkaline batteries causing damage, other than leaks...Here is the link:https://smile.amazon.com/gp/product/B07K5QT287/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1Tnanks!Rick

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: February 09, 2021, 11:26:35 pm
content: I don't see where it says that. It does say "(Please use Carbon or Low Eletric Current Batteries)" and in the Q&A, a lot of people say they use alkaline.I suspect they are advising against using rechargeables, as here:https://frankenmuthclock.com/blogs/news/best-batteries-for-your-battery-operated-clock.

author: CaptDon
author_rank: Super Contributor
timestamp: February 10, 2021, 02:29:32 am
content: When alkalines die they will most assuredly start to leak. Generally the clock will stop working long before the leak begins, BUT every time I have run across an abandoned clock that used a single AA alkaline the battery had already began leaking!!!! I have been through about 5 of them since the beginning of the new year. Going around to our empty offices (Now that the piece of crap company I work for does all the drafting in India and most of the design in China and they all suck!!!) and taking down all of the dead clocks with dead leaking batteries!!!

author: rickthegeek
author_rank: Newbie
timestamp: February 10, 2021, 09:19:02 pm
content: Well, I've always used the basic won-hung-lo alkaline batteries, the store brand, or the Amazon basic batteries, and I generally only look at the back of the clocks in my house twice a year when the time changes occur. I've never had an alkaline battery leak in a clock that I know of.I have never looked closely but is it even possible to find the older CZ style batteries in stores?(Personally, I like the clocks that plug into a special recessed wall outlet but I haven't seen any of those sold in a long time! I still see the outlets in houses, often with a battery clock hung over it!)

author: tooki
author_rank: Super Contributor
timestamp: February 10, 2021, 11:09:53 pm
content: Quote from: rickthegeek on February 09, 2021, 11:18:53 pmHuh? The last product image says to use carbon or alkaline.
Quartz crystal frequency is wrong - Page 1
Forum section: electronics / projects

author: RealJavabot
author_rank: Newbie
timestamp: November 04, 2023, 07:09:44 pm
content: Hello, I’m working on a pcb using the nrf52832, and the OS (Zephyr) crashes whenever I try to use bluetooth. This is due to some error implying timing issues. I have the dev board, and measuring the crystals on there gives wildly different frequencies than on my pcb. See below:I attached an image of the PCB.frequency (Hz)peak (mV)low(V)my board X131.3M66-56my board X232.3K13.6-13.6dev board X133.3M54-55dev board X233.3K20-24.8My theory is that this is caused by poor pcb design. I started with the reference design and tried to build around it. Maybe not enough vias leading to parasitic capacitance skewing the frequency too much? Please let me know if you have ideas.

author: RealJavabot
author_rank: Newbie
timestamp: November 04, 2023, 07:15:57 pm
content: Nevermind, the caps for the quartz crystal have pads that aren't connected.

author: miket6000
author_rank: Contributor
timestamp: November 04, 2023, 07:38:24 pm
content: A very quick skim showed at least 4 nets that are not routed. If you had run the DRC it would have shown you these. Given the time for loop backs and having the boards manufactured again (in this case you can just bodge it, but that won't always be the case) DRC is always worth running just before you generate your final Gerber's.
Quartz heating tubes - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: March 01, 2025, 08:04:51 am
content: Good morning (o;Have a Ninja 8-in-1 pizza oven here which has in total six quartz heating tubes...The top three have a marking stating 240V/650W and show a resistor value of around 86R.Lower three have a marking of 240V/335W and are connected in parallel, but show a resistor value of 142R.Are there any special precautions to take care with those Quartz IR heating tubes or can I just assume those are just a resistive load?

author: coppercone2
author_rank: Super Contributor
timestamp: March 01, 2025, 08:13:51 am
content: resistance might change with temperature but its only really a problem with certain ceramics like MoSi2 (or is it something else that sound similar?), which have a really low resistance when their cold and get high resistance when their hot, or some microwave suceptors that need pre-heating before they work like heating elements when exposed to microwaves, and some of those elements have a issue with some chemicals at high temperatures (i.e. they will like literarly burn up if you run it in a non - vacuum at high temperatures, or be incompatible with certain gases like nitrogen. bI believe the rule of thumb is something along the lines of, if your oven gets hotter then maybe 1300 degrees Celcius, and usually involving a vacuum chamber, you might have to do something special.and some heating elements that get real hot don't like DC, because the magnetic field makes them sag and bend (again, this is kiln stuff)you got 'easy mode'

author: davorin
author_rank: Unknown
timestamp: March 01, 2025, 08:49:27 am
content: I guess those tubes are just regular IR quartz tubes found also in those cheap room heaters...Basically a heating resistance inside an inert gas for reaching higher temperatures...and just saw that on the original PCB the bottom three tubes are just switched on/off by a relay.Hooked up one tube to my isolation transformer, though that can't go up above 1.6A....but resistance seems to be kinda constant:I definitively need more measurement and power supply gear (o;

author: davorin
author_rank: Unknown
timestamp: March 01, 2025, 09:18:04 am
content: Okay..did a first run with just one tube...starts at around 625W@230V AC and goes down to 615W.Waiting to cool down and do a second run with two tubes and measure the temperature profile again.

author: davorin
author_rank: Unknown
timestamp: March 01, 2025, 10:25:00 am
content: Now with two top 650W tubes.....the odd curve at the end did come from when I was playing with the convection fan (o;Seems two tubes are enough as it meets the 100W per liter...but there are still four more as a reserve....
Qucik question aboyt USB and SD Card EMI Protection  - Page 1
Forum section: electronics / projects

author: Twistx77
author_rank: Regular Contributor
timestamp: May 03, 2016, 10:18:00 am
content: Hi,I have a doubt about were to place a IC for EMI protection. I'm using a TPD4E0001 because is not that expensive and is really practical. My doubt arrises from the fact that the datasheet shows a picture were they place the IC between the USB connector and the resistors for the lines. I would normally place the TPD after the resistors so the resistors limit (at least a bit) the current.What do you guys think is the best practice?http://www.mouser.com/ds/2/405/tpd4e001-534314.pdfçThank you.

author: ConKbot
author_rank: Super Contributor
timestamp: May 03, 2016, 12:02:32 pm
content: As I understand it, lowering inductance is important, as a long trace can build up more energy during an esd event, so the clamp has more work to do.Its also important to have a resistor between the esd diode clamp and your i/o getting protected. The diode may only clamp the io to 6-20v (depending on the diode clamping voltage) a resistor between the clamp and the io limits how much current can flow through on-chip protective diodes to survivable levels. 20v is a lot easier to limit then 20kv with a resistor.

author: Twistx77
author_rank: Regular Contributor
timestamp: May 03, 2016, 09:23:47 pm
content: Quote from: ConKbot on May 03, 2016, 12:02:32 pmThanks. If I understand correctly you suggest to put the resistor close to the IO which is what I'm doing now, and just after that the clamp. The problem is that in the datasheet as you can see is done with the resistor after the ESD diodes so I'm not sure know what is the best way to do it.Anyone else has a suggestion?
query about a product - Page 1
Forum section: electronics / projects

author: Ronan Keets
author_rank: Newbie
timestamp: September 15, 2015, 11:56:24 am
content: hello all,I am trying to replicate the PCB design shown as an image in the below link. I have looked at the device datasheet and understand the device itself fairly well. However I have never done any high power PCBs before and needed to know are there any special things that I have to account for when designing PCB that can handle 10A or so currents. I read something about impedance controlled PCBs etc, do I need those for this? Also where can I get such PCBs made in the US, at a lower cost.http://www.ensembletech.in/portfolio-items/prototyping-dual-h-bridge-drive-for-under-water-rov/

author: nctnico
author_rank: Super Contributor
timestamp: September 15, 2015, 11:59:35 am
content: No need for impedance matching. Google for a PCB trace width calculator and enter the currents into it.

author: Ronan Keets
author_rank: Newbie
timestamp: September 19, 2015, 10:36:00 am
content: thanks will look to it ..
query about a product - Page 1
Forum section: electronics / projects

author: Mark Webber
author_rank: Newbie
timestamp: September 01, 2015, 07:25:34 am
content: Hello All,I am looking for a product like this, a break out board that I can use either with Xbee like modules or the Chinese HC type BT modules. Basically I am looking for a board that combines a FTDI IC and has options to use either of these types of modules. The link is from an Indian manufacturer, looking for something like this in the US. TIA.http://www.ensembletech.in/portfolio-items/prototyping-usb-to-multi-protocol-wireless-converter/
Query on RF LNA saturation? - Page 1
Forum section: electronics / projects

author: rfengg
author_rank: Regular Contributor
timestamp: March 03, 2023, 03:07:44 am
content: All,Need your advice on query regarding RF LNA saturation?I have a wideband RF LNA with specs of 20dB gain from 10Ghz to 30Ghz with a max rated output of 11dBm.When I input a clean RF sine into the LNA at 24Ghz, the LNA output works great and gives me exactly 10dBm o/p with -10dBm input (i.e. a gain of 20dB)However, when I feed the LNA from a wide band RF mixer which is driven by an LO of 18GHz @5dBm and IF of 6GHz @0dBm, the maximum RF output I get @24GHz even after considering all losses due to cables, is only 6dBm. (gain of 16dB).Increasing and decreasing the LO and IF levels does not help in increasing the 24GHz output.If I remove the LNA and measure the mixer output on a spectrum analyser alone, the RF output is indeed -10dBm.The mixer also outputs the LO of 18GHz and IF of 6GHz, as well as 12Ghz and 24Ghz as well as additional frequencies due to intermodulation, so is this why the output saturates at 6dBm or is there something else I should worry about?I am trying to convince myself that if the data sheet says the LNA max output is 11dBm with 20dB gain , this is valid only for a pure tone with no harmonics. If we drive the LNA with many tones, then the total output may be 11dBm but you obviously cannot expect all tones to get a gain of 20dB.....what do you all think?The specs of the mixer as per the data sheet look fine otherwise.......

author: moffy
author_rank: Super Contributor
timestamp: March 03, 2023, 03:43:13 am
content: Modulation of an 18GHz carrier by a 6GHz signal gives equal parts 12GHz and 24GHz, the 24GHz should be only 1/2 the output, if 100% modulated, if less than 100% you also have the left over carrier signal.
Quest for a tiny display; repurposing projector LCD's? - Page 1
Forum section: electronics / projects

author: Bendba
author_rank: Regular Contributor
timestamp: June 14, 2018, 12:36:35 pm
content: Hi,start laughing, I came up with another silly idea.Does anyone have ever re-purposed a LCD projector's display "chip"?I have been looking for a while for a very small video display for a virtual reality kind of project. The most comfortable to stare at for a long time that I found so far (within my budget anyway) is CRT viewfinders. The pixelation of digital displays is pretty painful to stare at. And it seems that there isn't any small, high definition displays easily available, else than smart phones.But in projectors, they manage to fit crazy resolution displays on tiny LCD's. I pulled apart a few projector with a three monochrome 1280*1024 LCD's measuring only 18mm diagonally.The thing is, I can't seem to find any datasheets for them (why would I?).Does anyone know if there is any kind of standard? I'm expecting some type of LVDS system.I don't know if I didn't search for the right thing or if there just isn't anything out there about it. If nothing is out there, it's probably not worth it.Any info would be helpful.Thanks

author: smoothVTer
author_rank: Regular Contributor
timestamp: June 19, 2018, 02:41:14 pm
content: Its true; small, high-def displays are not very common. There are however a few players in the market.eMagin is one such vendor that makes microdisplays of HD and UHD resolutions. Be ready to pay $500+ per each display.Another is microOLED. Price points are similar.
opamp questions - Page 1
Forum section: electronics / projects

author: arh8080
author_rank: Newbie
timestamp: April 27, 2016, 04:35:20 pm
content: Hi, Does anyone know how this circuit working?

author: Zbig
author_rank: Frequent Contributor
timestamp: April 27, 2016, 04:37:48 pm
content: While browsing the forum, looking at the post subjects, how many of them say "Question"? Why is that, what do you think?

author: max_torque
author_rank: Super Contributor
timestamp: April 27, 2016, 06:18:28 pm
content: Quote from: arh8080 on April 27, 2016, 04:35:20 pmANSWER: Yes
Question about 3V3 <=> 1V8 level shifter - Page 1
Forum section: electronics / projects

author: cmumford
author_rank: Contributor
timestamp: February 21, 2021, 01:22:45 am
content: Hi there:I'm using a 3.3V to 1.8V level shifter for the first time to communicate with a 1.8V chip via I2C. The level shifter is theTI LSF0204D. I probably screwed up soldering the incredibly tiny BGA chip, but before I attempt to fix that I took a look at the I2C traffic.Attached is a capture of my initialization message. The first two rows (chan 1&4) are the 1.8V I2C signals coming out of the level shifter, the second two rows (chan 2&3) are the 3.3V I2C signals. I see two things that are odd:The 1.8V SCL signal trends up about 0.3V, and then returns to it's prior levels.It seems to produce a negative voltage (i.e. below the 4 indicator on the left).I am using 100Ω pull-ups on the 1.8V side of the LSF0204D (seeschematic) as per the datasheet (section 10.2.1.2.1.1). My scope can decode both sets of signals just fine, but I'm not sure if this will be understood by my 1.8V chip (LM8330).Does my 1.8V I2C signaling look OK, or might it be the cause of my issues? I've tried both 100KHz and 400KHz speeds and neither talk to the chip.thx everyone.
Question about a product existing for a camera microprocessor  - Page 1
Forum section: electronics / projects

author: avb284782235
author_rank: Newbie
timestamp: November 22, 2022, 01:30:31 pm
content: Hello, sorry I’m advance if this is not the right section to post the question. I am looking to combine ntsc signals from at least 2-4 cameras, and have them combined/ superimposed together to have one output with low latency. Specifically, I am trying to combine 4 ntsc signals from 4 cameras with telephoto lenses, spaced out to have the right framing where the image borders intersect, and have a processor join these images together into a seemingly higher resolution image than just one camera has by itself.My goal is to use 4 flir lepton sensors with ntsc output breakout boards, and have these ntsc analog outputs combined via some sort of microprocessor to have one low latency output that can be used to go to an analog video transmitter. Thank you in advance.

author: donmr
author_rank: Regular Contributor
timestamp: November 22, 2022, 03:53:17 pm
content: First, NTSC signals are ANALOG so you will need some A/D converters. These typically run at about 12 MHz so you won't be using the converters in common small micro-controllers.Second, look at the amount of data that needs to be processed (width * height * frames_per_sec * number_of_channels). That will tell you how many pixels need to be handled each second. Then look at how many operations the algorithm needs. Depending on this number you might conclude that you need a *very* fast processor or some custom logic (like an FPGA).And of course to output NTSC you will need to convert back to analog again.Once long ago people did this kind of operation all in analog with some tricky circuits.Once a bit later you could buy A/Ds and D/As specially made for NTSC & PAL signals. I don't know if any of those are still available.

author: inse
author_rank: Super Contributor
timestamp: November 22, 2022, 04:33:49 pm
content: You are looking for a genlock device
Question about an amplifier for a sensor coil - Page 1
Forum section: electronics / projects

author: dimkasta
author_rank: Regular Contributor
timestamp: April 10, 2017, 12:14:28 am
content: In one of my projects, I have to get the input signal from a sensor coil wrapped around the moving magnet of a BLDC motor.The coil is ~5.5 Ohms, has a centre tap and gives a signal of around 2mV at 50-70HzWhat I want is to setup an amplifier to get the signal into 5V territory so that I can sample it with an ADC.What I was looking at is something like INA128, INA111 or ina121 instrumentation opamps and hook up the coil with its centre tap to ground to provide the bias return. Although I would prefer something that would work directly with single supply voltage to avoid extra stuff.I would appreciate any suggestions before I pull the trigger on some samples and start goofing around on the breadboard.Thanks in advance

author: Kleinstein
author_rank: Super Contributor
timestamp: April 10, 2017, 04:45:41 pm
content: With just a single supply you would need to have a DC bias somewhere in the middle, to be inside the input common mode range of the INAs. This could be just a divider at the supply. For the output the ref input of the INA would need to be set to about the center of the ADC range, usually from a low impedance source, like a divider, buffered with an OP.An alternative solution would be using just OPs instead of an INA. AC coupling like describes by blueskull would be the easier way.
Question about analot meters and specifications - Page 1
Forum section: electronics / projects

author: zaoka
author_rank: Frequent Contributor
timestamp: September 11, 2013, 08:03:56 pm
content: If I meter is rated 50uA does it mean if I supply 50uA current that it should make full deflection?

author: madires
author_rank: Super Contributor
timestamp: September 11, 2013, 08:11:01 pm
content: Simple answer: yes!
Question about apparent power of transformer - Page 1
Forum section: electronics / projects

author: namster
author_rank: Regular Contributor
timestamp: September 01, 2019, 01:49:47 pm
content: an example of a 250 Watt Isolation Transformer Design was given in the transformer and inductor design handbook ,i don't understand why the apparent power was calculated by summing the Primary Power and charge Power ?

author: IanB
author_rank: Super Contributor
timestamp: September 01, 2019, 03:23:45 pm
content: They are basically saying that the primary winding has to handle the total power and so does the secondary winding. So the total apparent power "seen" by both windings inside the transformer is the sum of the input power and the output power.I don't quite understand this, but that is what they are saying.

author: Benta
author_rank: Super Contributor
timestamp: September 01, 2019, 05:00:10 pm
content: What they're saying is, that secondary power is 250 W to the load. This is a design specification.Primary power is 263 W.You're supposed to allocate the winding cross-section areas accordingly to ensure equal power sharing. As the core material is also mentioned, you should probably add in magnetizing current for the primary calculation.

author: namster
author_rank: Regular Contributor
timestamp: September 01, 2019, 06:49:33 pm
content: @Benta that's itafter some research it appeared that the apparent Power is calculated in a way that we chose the right Core geometry Kg which allows the equal power sharing
Question about cable internet interface  - Page 1
Forum section: electronics / projects

author: Excavatoree
author_rank: Frequent Contributor
timestamp: February 11, 2020, 01:05:14 am
content: This is a long shot, I know. I'm in the US, but I suspect that similar devices may be used elsewhere.I have what's known as "cable TV, with internet." There is an appliance that connects to the RG6 cable, and connects to my network router, as well as my POTS. (telephone)I had a problem, so I was checking the connections, and I got a shock from the shield of the cable. I thought it was a problem with my "drop," or maybe one of my Televisions, but it turned out to be the first thing I checked - the internet appliance.When it's sitting there, with nothing connected except the power, there is 30 volts AC on the shield connection of the RG6 input. It's high impedance, as with my body touching the connection, it drops to 10 volts. Of course, when my grounded cable is connected to it, it's at zero, but with my cable cut (the reason for the problem) I had that 30 volts on all the cable in the house.Is that sort of thing normal. or is my device defective. The technician that diagnosed the cable break in my yard had no idea, and was in the "well, it works, so don't worry about it." camp. "We really don't measure any voltages" he said.For those not in the US, US cable companies are know for their HORRIBLE customer service, and the inability to speak with anyone who knows anything. All I can get is "check your connections" and " We'll send someone out." Well, they did that, and he didn't know either.

author: ejeffrey
author_rank: Super Contributor
timestamp: February 11, 2020, 01:14:45 am
content: That's pretty much true for any ungrounded appliance with a switch mode power supply. The culprit is the class-Y capacitors required for EMI shielding. There will be one from each power line (live and neutral) to the enclosure ground of the unit. They form a voltage divider that gives you ideally half the supply voltage (i.e., 60 volts)when open circuit, but can be less if there is any leakage to ground.In a grounded power supply that leakage current would be conducted to ground, but without that it just floats at half the supply. Its normal and not really anything to worry about from a safety perspective although it can be a cause of equipment damage when you hotplug connections to a grounded instrument.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 12, 2020, 09:33:28 am
content: Hi, we have this question almost weekly.https://www.eevblog.com/forum/projects/voltage-on-ground-of-powersupplies-normal-or-not/
Question about calculating Junction temperature and where you take the PCB temp? - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: November 25, 2024, 03:37:56 pm
content: I wanted to see how other folks are calculating junction temperatures. In the past, I have used the surface board temperatures, the ThetaJC and the ThetaCB to calculate the junction temperature. Recently, I saw where instead of using the surface board temperature, they are using the mid-point internal temperature. For example, if the PCB uses 12 layers, then the temperature of the 6th layer is used as a reference. Using this temperature leads to higher ThetaCB because the reference is the 6th layer instead of the surface layer.is there anybody out there that is using the mid-point layer as the reference for the board temperature? What has been you experience. I welcome any feedback.RB
Question about creating a LIB timing file for a mixed-signal hardmacro  - Page 1
Forum section: electronics / projects

author: emm386
author_rank: Newbie
timestamp: September 03, 2024, 06:04:06 pm
content: Hi all, I'm trying to manually write a liberty timing file (.LIB) for a mixed-signal hardmacro shown above. There are four outputs for this mixed-signal hardmacro: deserialized data (DESER_OUT[0~11], CLK_OUT, and RST_OUT). For the following digital RTL to be free from any timing violation, I need to come up with fairly accurate timing models for this hardmacro. While I was working on the LIB file, I've encounted few questions that I could not answer myself, so decided to get some help from this forum.The tricky part of this setup, in my opinion, is that the pin direction of both CLK_OUT and RST_OUT are set to output. Because of this, I have quite a bit of confusion since most of examples in liberty user manual does not cover this type of scenario.Q1: For DESER_OUT, shall I have two timing description, one with CLK_OUT being related_pin, and the other with RST_OUT?Q2-1: One of the important timing information here is the skew between rising edge of data and rising edge of CLK. One method I am about to try is setting the CLK_OUT as related_pin for DESER_OUT bus, and then come up with LUT for cell_rise and cell_fall based on the simulation results. Do you think this is a reasonably good approach?Q2-2: Do I also need to do the same thing for CLK_OUT and set its related_pin to RST?Q3: When RST is high, DESER_OUT and CLK_OUT are forced to go to low (0). when RST is low, then DESER_OUT and CLK_OUT are active and starts toggling. In this situation, what is the most appropriate timing_sense value for DESER_OUT when its related_pin is RST? is it supposed to be positive_unate? negative_unate? or non_unate?Q4: what about timing_types? What would be the most appropriate timing_types for all three signals?Q5: are cell_rise, cell_fall, rise_transition, fall_transition good enough for timing description in general?Any feedback/comments would be really appreciated !
Question about crystal mentioned in Daves video - Page 1
Forum section: electronics / projects

author: laejf
author_rank: Regular Contributor
timestamp: September 12, 2020, 09:27:34 am
content: In Daves tear down of the DT71 tweezer he noticed a crystal on the board but said it was not a crystal oscillator because of the big pad. What is such a crystal for if not an oscillator?Video at timestamp:https://youtu.be/DTdycgOalG4?t=932

author: Phoenix
author_rank: Frequent Contributor
timestamp: September 12, 2020, 09:55:56 am
content: A crystal would need to be connected to a separate oscillator circuit to produce a clock. This crystal is probably connected to the microcontroller on the other side of the PCB. The microcontroller will have the oscillator circuit inside.I would interpret Dave's comments that it's not a "cystal oscillator" as not having the oscillator circuit built in. These need 3 pads (power, clock, ground) - and can often have 4 pads (e.g. enable or N.C) because they are square.

author: laejf
author_rank: Regular Contributor
timestamp: September 12, 2020, 09:58:17 am
content: Oh i see. Thank you!
question about feedback loop gain measurement - Page 1
Forum section: electronics / projects

author: analogRF
author_rank: Super Contributor
timestamp: August 09, 2019, 02:42:42 pm
content: I would like to do some experiments on measuring feedback loop gain in amplifiers and power supplies but I am new to this particular topic.I only have function generators and oscilloscopes (separate).If I understand correctly, the purpose of the injection transformer is just to isolate the ground of the function generator that injects a smallsignal to the control loop via the injection resistor (e.g. 50 ohm) and also isolate any DC offset from the function generator, right?If so, my question is what if I run my function generator from an isolation transformer (instead of the wall plug) and then directly connectthe output of the function generator (with zero DC offset and small signal like 10mVpp or so) to the injection resistor in the loop? It seems to methere would be no need for a wideband injection transformer?EDIT: maybe noise or 50Hz interference would be problem?

author: Audioguru again
author_rank: Regular Contributor
timestamp: August 09, 2019, 03:47:11 pm
content: What is an "injection transformer" or an "injection resistor"?An amplifier circuit has its negative feedback directly connected to it and its input is directly connected to its signal source by a shielded cable that shields against 50Hz and other interference.

author: David Hess
author_rank: Super Contributor
timestamp: August 09, 2019, 04:06:39 pm
content: The problem with isolating the function generator is that considerable common mode capacitance to Earth ground still exists.I have gotten adequate results by just AC coupling the signal generator with a capacitor at the injection point.

author: analogRF
author_rank: Super Contributor
timestamp: August 09, 2019, 04:28:40 pm
content: Quote from: David Hess on August 09, 2019, 04:06:39 pmHow, if the fgen ground is not fully isolated? it shorts the bottom of the injection resistor to the groundwhere one channel of the scope is also measuring at that point

author: David Hess
author_rank: Super Contributor
timestamp: August 09, 2019, 04:46:54 pm
content: Quote from: analogRF on August 09, 2019, 04:28:40 pmThe grounds are in common. The signal is injected as a current through the series resistor and the capacitor removes the DC component. If that is not sufficient, then I build a current mirror into the circuit to drive the feedback node with a high impedance.

author: magic
author_rank: Super Contributor
timestamp: August 09, 2019, 09:05:21 pm
content: I certain cases like opamps it is possible to build a test circuit which makes the amp amplify its own error signal so that it can be compared with the output on a two channel scope.
Question about Flash memory components: are there chips with Serial AND Parallel - Page 1
Forum section: electronics / projects

author: jvcastel
author_rank: Newbie
timestamp: October 05, 2022, 09:01:46 am
content: Greetings to all fellows at EEVblog,I'm interested into en EEPROM replacement, that is to take out an EEPROM and put a Flash memory instead. I saw that ther are several Flash memory devices that are pin compatible with the old 27CXXX Memory IC's and PCB designs to do this also. Now my question goes onto this: are there Flash devices than could be programmed as a serial device either via SPI or I2C and read as parallel memory by the host System? That way the host reads it as an old EEPROM but could be programmed by a Microcontroller if needed? Am I dreaming of something that doesn't exist? I appreciate your comments on this. Thanks!

author: macboy
author_rank: Super Contributor
timestamp: October 08, 2022, 05:43:51 am
content: Parallel FLASH with JTAG can usually be programmed over JTAG, but it's difficult and slow.