hybridfree/eevblog-posts huggingface dataset:
Replacing unknown diode - Page 1
Forum section: electronics / beginners

author: taste_tester
author_rank: Regular Contributor
timestamp: December 01, 2022, 10:29:04 am
content: Hello,I need to replace a part which wasn't specified on a schematic, i'm not exactly sure what diode to use, is 1N4148 a safe bet to replace this? i don't think is a zener,i believe that Q8 shown, also not labeled in the schematic, is a 2SA1175 general purpose PNP.Kind regards

author: Circlotron
author_rank: Super Contributor
timestamp: December 01, 2022, 10:49:24 am
content: Yeah, I'd try a 1N4148. Fairly safe bet.

author: wasedadoc
author_rank: Super Contributor
timestamp: December 01, 2022, 01:33:38 pm
content: Are you sure it is faulty? In the electrical it is not doing a hard job which would increase its probability of failure.

author: connectTek
author_rank: Regular Contributor
timestamp: December 01, 2022, 11:29:30 pm
content: Looking at that photo I think you have way more bigger problems than the diode.The amount of corrosion is incredible.
Replacing usb micro connector - Page 1
Forum section: electronics / beginners

author: faust1002
author_rank: Contributor
timestamp: November 26, 2020, 09:34:46 pm
content: Hello guys,I am a beginner, who has no means of setuping a proper lab. That makes soldering, especially SMD components, hardly possible. I can still use some commercial services for that, for instance JLCPCB. I usually can get by with this. Unfortunately, JLCPCB in its component library doesn't have any USB connectors. This means that I would have to solder them on my own. The problem is that all horizontal connectors I found are SMD. Do you have any idea how can I replace them some other though hole component?To be fair, there are some connectors which have some pins through hole and some other SMD. This might help, but still I don't believe I would able to solder them.Kind regards

author: SilverSolder
author_rank: Super Contributor
timestamp: November 26, 2020, 09:39:25 pm
content: Quote from: faust1002 on November 26, 2020, 09:34:46 pmNonsense - all you need is a soldering iron (a Chinese Hakko copy for $30 is fine) and a pair of magnifying visors ($20).Then you just need some practice, which means watching a few videos on the University of Youtube, followed by actually soldering stuff.You'll be up to speed in no time, even a child can do it!

author: faust1002
author_rank: Contributor
timestamp: November 26, 2020, 10:07:11 pm
content: It's not about lack of skills / money / equipment, but lack of a proper space. I hardly have place for a breadboard and USB scope. Experimenting with a liquid metal and fumes (I have pretty ventilation system) in this environment sounds too risky.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 26, 2020, 11:56:41 pm
content: Quote from: faust1002 on November 26, 2020, 10:07:11 pmDo you have asthma or some other respiratory disease? If you crack a window open, the fumes from a small amount of soldering are completely tolerable... I even like the smell, personally, but that's probably just me!You could always use a little computer fan with a piece of activated carbon filter on it, if you think getting rid of the fumes is important?When I was 12, I was soldering in my bedroom with a Weller 100 watt gun that I bought for my newspaper round money... I had a piece of plywood that I used as a makeshift table on my bed or on the floor, or on my desk, depending on where was the least messy!Honestly, it has to be the simplest solution. No?

author: sleemanj
author_rank: Super Contributor
timestamp: November 27, 2020, 05:21:24 am
content: Err, you are going to have to solder the hypothetical through-hole connector just the same as you're going to have to solder the SMD one. Through hole mini (and maybe micro) USB exist but I would not recommend, pin pitch is small, SMD will be easier.Flux, soldering iron with a fine pointy tip (the pins can be hard to reach on some connectors), and fine solder.If you don't care about looks or board space, you could always just buy a load of USB breakouts and use them like modules you solder onto your board. Readily available from the usual chinese market places.
Replacing wet electrolytic caps with solid polymer in tube equipment - Page 1
Forum section: electronics / beginners

author: KlAndrew001
author_rank: Newbie
timestamp: April 11, 2020, 07:37:27 pm
content: In older analog equipment, such as tube radios/transceivers, could wet electrolytic capacitors (especially the smaller ones, which are more prone to drying) be replaced with modern polymer capacitors?The main uses of electrolytic capacitors in tube equipment (which I look for replacing) include:Cathode decouplingAudio couplingRF decoupling (eg oscillator circuits in a transceiver)And DC filtering, of course, but here are larger values at higher voltage ratings, harder to get with polymer caps.The objective is extending the life of the device by replacing components that have lower life expectancies with higher ones (in this case, replacing wet el caps with solid polymer caps)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 11, 2020, 08:42:39 pm
content: Sure, but why? Cathodes don't need impedances much lower than 1/Gm; coupling capacitors and bypasses don't need large values; and HV caps the same over again but at higher voltage ratings.You can get 105, even 125C and higher ratings, with 5000hr+ life, and you don't need to put the caps right beside super hot tubes and whatnot. Can always relocate replacements, especially since they're so much more compact than the originals...Plus, polymers degrade in a similar way, though due to moisture ingress rather than electrolyte outgress.If you want ~infinite lifetime, consider using the film-in-oil caps that are popular among some audiophiles. Very bulky, not going to drop into original equipment, but it will last. You might be able to get tantalums in that kind of size, but the price increases exponentially, and I suspect that the price elasticity is not as irrelevant as you seem to imply [by not mentioning cost at all in your post]...Tim
Replacment LED for a discolight - 60 watt 5x5 led array Eurolite - Im stuck - Page 1
Forum section: electronics / beginners

author: sebrassino
author_rank: Newbie
timestamp: May 05, 2020, 03:15:03 pm
content: Hi all,A friend of me has seen all his disco sound and light equipment stolen out of his storage. Very sad of course. But from other friends he got several basic replacement equipment. Wich is good to see. Between that stuff were 5 LED scanners. Eurolite's TSL-300. With several working, several with blown LED's.I did some investigation. Contacted suppliers via official ways. But replacements are not available. Or even unknown. Basically the device is obviously discontinued. I wanted to replace the leds so he can use the lights. Or sell as a working set so he can search something that suits his needs. But yeah, no results on the search. I couldn't even find a picture or obsolete part number.In the attachments are 3 pictures. One with the led mounted on the heatsink with just 1 array working. Two a "working" one with one dead array. Three the led taken out.So I did some measurements on the working ones. The supply is around 16-17 volt. Wich is the original power supply. no further details on that too. Except a part number of BS-D002.Although on that one array of the led is dead. So my basic calculations are 5x3=15 volt. under load. Maybe abit higher ofcourse. The wattage specified at 60 watt. The size of the led is 18x18mm.This led looks very similar to the wide spread cheap leds you find on alieexpress and ebay. But the arrange of the leds is different in these.How is this type of led called. Or how is the package called. Does anyone know a supplier that delivers these. Or do you have tips where to search. Ive searched on mouser/digikey and others but cant find it. Im stuck right now.Thanks a lot. Sebas
replacment LG TV Cap - Page 1
Forum section: electronics / beginners

author: dablac01r
author_rank: Newbie
timestamp: July 07, 2017, 06:30:17 am
content: The main capacitor on the power board burst. It is a Samyoung 550sv 120uf 460v I can not find this part anywhere can I use a 120uf 450v instead. If not can you help me locate a superior capacitor.

author: Zero999
author_rank: Super Contributor
timestamp: July 07, 2017, 08:34:35 am
content: Generally it's not a good idea to go for a lower voltage part. Try to find one rated to a higher voltage, if you can't get one rated for 460V.Another headache is matching the PCB footprint.You probably could get away with 450V but it won't last as long as one rated to 460V. Go for 105oC temperature rating if you can and as low ESR as possible.I've just quickly searched RS Components and they have lots of 120uF and 150uF (you can probably use a slightly higher value) 500V capacitors.http://uk.rs-online.com/web/c/passive-components/capacitors/aluminium-capacitors/?applied-dimensions=4292049087,4292049457,4292047454,4292049502,4294455094,4294465685,4293569694

author: BMack
author_rank: Regular Contributor
timestamp: July 07, 2017, 03:49:49 pm
content: It's not good practice to go lower voltage but it will work.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: July 07, 2017, 08:13:08 pm
content: If it's a simple rectifier then the cap will have about 1.5 times the RMS mains voltage on it, so for 240v anything over 400v rating will work. The exception is if it's a power-factor corrected PSU, when it might have a step-up Buck converter giving up to 450v at the reservoir cap. Those are not so common in TV sets though.Some 120v PSUs have a voltage doubler, but this identifiable by having two similar reservoir caps.

author: wraper
author_rank: Unknown
timestamp: July 07, 2017, 08:20:05 pm
content: 450V vs 460V is only 2% difference, so does not matter at all. Actual working voltage should be around 380-400V.

author: wraper
author_rank: Unknown
timestamp: July 07, 2017, 08:25:41 pm
content: Quote from: IanMacdonald on July 07, 2017, 08:13:08 pmThey are common, actually I'm pretty sure it's one of them.Quote from: Hero999 on July 07, 2017, 08:34:35 amSuch voltage rating difference by itself would make nearly zero difference. Manufacturer and series is what matters.QuoteAnd none of those would fit there. Other than capacitors in RS catalog are snap in or screw terminal type, unlike this cap with leads on this PCB, it also seems to be of very low diameter and high length type.
reporting error in TI TPIC6B595 datasheet? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: April 02, 2017, 02:04:10 am
content: I found an error on a the TI datasheet from 2015 for the TPIC6B595 shift register. This seems to be the latest revision of the document.Is there an official way of reporting datasheet errors to TI?Notice how the Pin Functions list says SRCK is 15 but it's actually 13.

author: Domagoj T
author_rank: Frequent Contributor
timestamp: April 02, 2017, 06:06:00 am
content: Nice catch. I've been using the little buggers for several years and haven't noticed it.Anyway:http://www.go-dsp.com/forms/techdoc/doc_feedback.htm

author: dentaku
author_rank: Frequent Contributor
timestamp: April 02, 2017, 12:43:29 pm
content: I just noticed that link is right at the bottom of the page of the .PDFThanks.
Repurpose an h-bridge as "double switch" - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: March 19, 2019, 09:32:13 pm
content: Hi,I have, in my "bin" some h-bridge circuits that are left from a previous project. These are not single ics, but made up with mosfets, and used to drive a 12V brush dc motor.Currently I have a project where I have to switch some leds on and off, meaning that when one is on the other is off and viceversa. These are either blue or white LEDs but the rest of the circuit is 3.3V logic (but I have a 12V power supply). In order toget rid of these extra partsput to use those already assembled h-bridges, I thought of the circuit in the schematic below, thinking that putting a resistor in series with both LEDs would "take" the most voltage drop, thus protecting the reverse biased led (there's always one when the bridge is active) from dying.Is this a sensible idea? If not, is it at least an ok reasoning (albeit not best)? If not again, where am I wrong?Thanks

author: viperidae
author_rank: Frequent Contributor
timestamp: March 20, 2019, 01:03:27 am
content: You don't need to worry about reverse voltage if you wire one led to each output and their other terminal to positive or negative via a resistor.

author: Brumby
author_rank: Unknown
timestamp: March 20, 2019, 01:54:36 am
content: I don't see anything basically wrong with your idea - but I would consider using H-bridge switching as over-kill.

author: Moriambar
author_rank: Unknown
timestamp: March 20, 2019, 07:09:55 am
content: Quote from: Brumby on March 20, 2019, 01:54:36 amThanks, indeed it is.
Repurposing LCD car DVD player faceplate screen? :P - Page 1
Forum section: electronics / beginners

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: December 28, 2013, 02:06:37 am
content: Trying to figure out if this LCD can simply be fed a video signal, but not really sure where to start....I'm wondering if the DVD_C_IN and DVD_Y_IN are a chrome/luma input...The AUX_L, AUX_R and AUX_CVBS run to an AUX input connector on the front panel.SCL and SDA appear to be for the serial touch screen.D+, D- and USB 5v are for a front USB port...Anyway! not the point... does anyone actually know what the IC used on this is?

author: amyk
author_rank: Super Contributor
timestamp: December 28, 2013, 10:37:50 am
content: According to Google, that would be a Terawins T101A. Datasheethere...

author: owl_uk
author_rank: Contributor
timestamp: December 28, 2013, 04:08:18 pm
content: CVBS is probably the one you're looking for. CVBS stands for something or the other, but its the same as composite video, i.e. the one you can feed from a single coax cable.

author: codeboy2k
author_rank: Super Contributor
timestamp: December 28, 2013, 10:23:04 pm
content: Quote from: AmmoJammo on December 28, 2013, 02:06:37 am... and that chip is a Terawins T101A Video Display Controller, which happens to have 9 CVBS inputs (!) and is switchable by the I2C lines (SDA, SCL)The Y/C lines also go to the chip.The datasheet is attached. (zipped, 2 part RAR files)...I had to split it (RAR) since the file size limit is 1MB per file and the datasheet is 1.3MBI had to ZIP the 2 RAR parts since the forum only allows ZIP upload, not RAR uploads directly.You can also get it here from Electrotanya, but you might need an account, thats why I attached it too.http://elektrotanya.com/terawins_t101a_video-display-controller.pdf/download.html

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: December 29, 2013, 11:42:18 pm
content: Thanks for the assistance, I shall look into this further.No clue why I couldn't find the datasheet :pMight need to modify this a bit...
Repurposing VGA CRT as composite monitor - Page 1
Forum section: electronics / beginners

author: karoru
author_rank: Regular Contributor
timestamp: May 28, 2016, 04:56:02 pm
content: Hey, I've got this old Datas CH-0423V VGA B/W computer display. It has nice, crisp picture and I'm wondering about repurposing it as composite monitor for my old gaming systems repair.Any ideas if that's doable easily? Most googling gives me some Chinese composite to VGA upscalers, but I really don'tcare about getting some fancy uber-cool resolutions and other nice features, I just want something to connect oldgaming system to check if it's working and if the picture makes any sense. I remember in the magic days of CRTtechnicians made some hacks to add composite to old TVs (with or without any concerns about things such as galvanicisolation, nothing beats making your VCR chassis hot by connecting it to a TV), but I wonder whether that's easilydoable on a semi-modern computer display (it has only VGA input)I know how to not kill myself with flyback and all the funny things inside, so that's not a concern.

author: helius
author_rank: Super Contributor
timestamp: May 28, 2016, 05:08:25 pm
content: For some reason, this question is coming up a lot, now.What signal does your monitor use? I tried searching but got no results in a language I can read.Normal VGA displays cannot display NTSC or PAL signals, the frequencies are out of range. The simplest approach I can think of would be making a "single line TBC" and turning the 60 fields/sec into 60 frames/sec with line doubling. The cheap Chinese upscalers may be using that approach.

author: karoru
author_rank: Regular Contributor
timestamp: May 28, 2016, 05:21:04 pm
content: Yeah it's normal VGA display, usually works in 640x480.This model was quite popular years ago in Europe but information about it is pretty nonexistent, even in my native language most info I can see are protocols from some companies/government agencies about putting them into trash - looks like it was some random OEM company that offered them and went off business long time ago - I've never seen that brand at normal person's home, just commercial environment (mine was connected to some biological lab equipment, spectrophotometer or something like that)Yup, thanks for pointing my brain fart - sync frequencies will be far off, it won't work as easy as B&W TV composite job:)I'll try to play around with idea of making some homebrew upscaling, to the point I'd be sure I can't beat 20$ aliexpress scaler.

author: helius
author_rank: Super Contributor
timestamp: May 28, 2016, 06:09:05 pm
content: The single-line doubling approach will work for most game consoles, since they have a vertical resolution of around 240 lines, and are not really using interlacing. But it won't work for real interlaced signals like video tapes; to de-interlace those you need to digitize a full frame.
Reputable sources of electronic kits - Page 1
Forum section: electronics / beginners

author: caffeinatedbard
author_rank: Regular Contributor
timestamp: September 30, 2011, 12:01:14 pm
content: I am looking to buy some electronic kits and found these guys on ebay. Can any one vouch for them or suggest more reputable ones?http://stores.ebay.com/nightfireelectronickits

author: Jimmy
author_rank: Regular Contributor
timestamp: September 30, 2011, 12:02:47 pm
content: http://www.sparkfun.com/

author: caffeinatedbard
author_rank: Regular Contributor
timestamp: September 30, 2011, 12:22:16 pm
content: Jimmy, thanks for the suggestion. I have used them before. The nice feature is their kits are well documented etc. I have bought their RS-232 level shifter board and some other stuff from them.If it helps, I am looking more for an electronicdesignkit that has a vanilla assortment of analog, linear, SMTs, through hole components. I could easily just go on digikey and spend sometime on there but wanted to support the smaller guys like the adafruits, and sparkfuns of the hobby industry.Thanks

author: johnboxall
author_rank: Unknown
timestamp: October 02, 2011, 09:39:23 am
content: www.jaycar.uswww.altronics.com.auhttp://www.minikits.com.au/http://www.oatleyelectronics.com/www.kitstop.com.auwww.evilmadscience.comhttp://electronics-diy.com/store.php?sel=kitsGeneral "kit stores" are becoming fewer, and those that are around tend to specialise in one particular area (e.g. Arduino shields, RF things etc.)

author: grenert
author_rank: Frequent Contributor
timestamp: October 02, 2011, 04:47:40 pm
content: Rainbow Kits has a horrible 1997-looking website, but nice kits (which actually provide some explanation of how they work, unlike some kits):http://www.rainbowkits.comSome of the kits are available from Jameco, if you happen to be ordering from them.

author: caffeinatedbard
author_rank: Regular Contributor
timestamp: October 03, 2011, 12:11:42 pm
content: Thanks for the suggestions guys. I must say @tronixstuff, you were right, general vanilla parts kits are becoming fewer. I had a hard time finding kits that didn't have a PCB included and that it wasn't targeted for some hobbyist platform (Arduino, PIC, etc.)

author: caffeinatedbard
author_rank: Regular Contributor
timestamp: October 03, 2011, 04:14:06 pm
content: I came across ladyada's wiki and found some very good information regarding different places to buy electronics. You might also want to check out her other pages.http://www.ladyada.net/library/procure/hobbyist.html
Request advices on a 18650 charger claims can revive batteries - Page 1
Forum section: electronics / beginners

author: Chen Li
author_rank: Newbie
timestamp: March 02, 2022, 02:14:33 am
content: Hello everyone,I recently found a Chinese brand Xtar claims their charges can revive 0 voltage batteries. But I really doubt, I know maybe they can charge the dead batteries with a couple ma and the dead batteries will have some voltage levels. But the capacity and esr will be awful either.Does anyone has chargers with same kind claims? And I really want get some advice cause I have bunch dead batteries 😂

author: sleemanj
author_rank: Super Contributor
timestamp: March 02, 2022, 07:52:52 am
content: 0v cells won't be worth dicking about with, just put into the battery recycling.1._v I have a few that have been brought back to live helpful lives for low current purposes.Anyway, any TP4056 (assuming we are talking about Li-Ion, not LiFePo4) will do the job, it's nothing special, just set it's current low, do it in a safe place, monitor to make sure it takes a charge, and then see how it looks for self discharge and capacity.
Request for a Ariston breadboard  - Page 1
Forum section: electronics / beginners

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: September 20, 2018, 01:14:43 pm
content: HiI was searching around ebay and i didn't find a breadboard branded Ariston like this:I have one and the thing about it is that it has screws underneath to secure the contacts and can be open to service metalic contacs or remove them to make clearence for higher voltages, like 230V, with back-to-back isolation transformer of course with 6VA power, since i don't wanna set it on fire.Were can they be found for sale? (Edit bad english) Or similar ones?

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: October 01, 2018, 10:47:07 pm
content: Hi here are some images of my breadboard with removed contacts to create gaps on the triac circuit in order to isolate them from the 230V ( isolation transformer ). They can be accessed by screws and taken out by a x-acto knife., rather than take double sided tapeI couldn't find any so far...

author: ebclr
author_rank: Super Contributor
timestamp: October 02, 2018, 12:53:56 am
content: This may solve your problemhttps://www.amazon.com/gp/product/B00TP0XVXO/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

author: Old Printer
author_rank: Frequent Contributor
timestamp: October 02, 2018, 01:42:16 am
content: Don't think I would want to handle a breadboard hooked up to 230 volts, or am I misunderstanding you?

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: October 02, 2018, 09:49:59 pm
content: It is not directly connected to mains 230V, but to a isolation transformer made by two 12VA back to back transformers. Removing the contacts inside the breadboard you can create gaps to grant better clearance and not relying on the double sided tape as isolator .. If i use a regular breadboard it will damaged the triac or the diac eventually.That's an neat board by the way, the 5eBoard. I can put some large caps well spaced.
Requesting EEV Discount code that works for TEquipment and Saelig - Page 1
Forum section: electronics / beginners

author: oldjim
author_rank: Newbie
timestamp: June 09, 2024, 05:05:15 pm
content: I hang out here but don't post often. I plan to purchase a Siglent SDS804X HD shortly and hope I can get the discount code from someone. I'm looking to purchase from TEquipment or Saelig. Any advice on one over the other in terms of the discount offered? Thanks. Jim

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 09, 2024, 05:59:49 pm
content: Do a bit of searching on the forum itself.I found this one, but it is an oldie:https://www.eevblog.com/forum/testgear/eevblog-members-discount-at-tequipment/msg2085649/#msg2085649Maybe there is more to be found.

author: aliarifat794
author_rank: Regular Contributor
timestamp: June 10, 2024, 09:56:05 am
content: Could not find any recent discount code for saelig.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 10, 2024, 10:46:12 am
content: This is basically the same link as pcprogrammer gave, but should take you to the last post, May, 2023:https://www.eevblog.com/forum/chat/special-price-for-eevblog-members

author: tautech
author_rank: Super Contributor
timestamp: June 10, 2024, 08:27:49 pm
content: Quote from: oldjim on June 09, 2024, 05:05:15 pmTHe Saelig code is only available on request as it is for members only.https://www.eevblog.com/forum/testgear/equipment-discounts-from-saelig/
Requesting i2c program for lpc11e36 microcontroller - Page 1
Forum section: electronics / beginners

author: kamalesh
author_rank: Newbie
timestamp: May 04, 2024, 09:17:44 am
content: Hello,I am new to this field. Actually, We are started working with lpc11e36 micrcontrollers.We successfully able to do the uart interface program with this microcontroller. But, for testing purpose, we have to do i2c program.I searched in many places and finally written one program for i2c.Now, After initializing the i2c, I checked with scope, there is no scl signal in scope. Program also stucked inbetween the progress and it is going to the event of i2c_wait.(particulary i2c_chipMasterSend function strucked).How to clear this error?Is there any other examples to move forward?Regards,Kamal

author: pcprogrammer
author_rank: Super Contributor
timestamp: May 04, 2024, 09:32:32 am
content: Hi Kamal,welcome to the forum. First of, it is not a good idea to use your email address as your login because it is displayed above every post you make. I reported it for you so the moderators can change it for you.Second, for better help post the code you made, so members can look at it and tell you what can be wrong.Here is a link to somecodegoogle showed when searching for "lpc11e36 i2c example code". It might not be for this exact microcontroller, but can be of help.

author: gnif
author_rank: Unknown
timestamp: May 04, 2024, 09:34:55 am
content: Displayed name adjusted anyway
Reset circuit? - Page 1
Forum section: electronics / beginners

author: Marsupilami
author_rank: Frequent Contributor
timestamp: June 03, 2023, 07:20:34 pm
content: Hi,What do you think this is doing? I'm really missing something here.This is a PCIe adapter board, and the input signal is the PCIe reset.I tried to reverse engineer based on the board:It would make a lot of sense IF resistor R4 was populated.But it isn't:What's even more interesting is that this is a similar PCIe board from another vendor, and it has a same looking circuitry but doesn't even have a location for what's R4 on the first one. You can see that the collector of Q2 and the base of Q1 is directly connected without anything else. There is no via visible from the other side either.(R5->R3; R3->R2)Did I misidentified the transistor as 3904? (Marking 1AM?)

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 03, 2023, 09:05:10 pm
content: It looks like they are taking about this type of Darlington Pair in this document. See the Sziklai Darlington section.https://www.electronics-tutorials.ws/transistor/darlington-transistor.html

author: Marsupilami
author_rank: Frequent Contributor
timestamp: June 03, 2023, 09:16:51 pm
content: Quote from: JustMeHere on June 03, 2023, 09:05:10 pmYeah, but that has one NPN and one PNP transistor, which makes sense. On this circuit, at least as far as the markings go they are identical.I'm starting to have the suspicion, that NVMe doesn't actually need the PCIe reset so it's always high, and on the purple board they did an easy DNP to set it, while the red board might be a knock off, and whoever copied the circuit had no idea what they were doing so they didn't add the optional of the R4 pullup, even though that makes the whole transistor thing moot. I don't know. It doesn't make much sense.

author: Benta
author_rank: Super Contributor
timestamp: June 03, 2023, 09:24:56 pm
content: Your circuit is a pull-up resistor (R3). That's it.

author: Marsupilami
author_rank: Frequent Contributor
timestamp: June 03, 2023, 09:38:46 pm
content: Here's another one. This time an M.2 form factor.The resistors are even have the same reference designation, and what do you know, R4 is populated.

author: Marsupilami
author_rank: Frequent Contributor
timestamp: June 03, 2023, 09:39:48 pm
content: Quote from: Benta on June 03, 2023, 09:24:56 pmThat's what I see too, but then why do they put the transistors there?
reset pin on attiny13a - Page 1
Forum section: electronics / beginners

author: m.m.m
author_rank: Regular Contributor
timestamp: June 27, 2014, 01:52:59 pm
content: I know it's a frequent question but I found no answer for my application. can I connect a switch to the reset pin of an MCU and connect the other side of the switch to +5v supply and use the reset pin as input without disabling reset or low voltage ISP? I wanted to make a tiny IR remote for the lights.

author: XOIIO
author_rank: Super Contributor
timestamp: June 27, 2014, 02:25:22 pm
content: I think you need to connect reset to ground, never used that chip myself though, but on everything I've using it is ground.

author: wraper
author_rank: Unknown
timestamp: June 27, 2014, 02:42:12 pm
content: You can't do that. So you must disable reset pin and use parallel or high voltage serial programming if you need to reprogram it. Otherwise it will work like normal reset and MCU will restart when you pull this pin to GND. What the point to connect other side of the switch to the +5V when you obviously can't pull down side of the switch which is connected to this pin.

author: wraper
author_rank: Unknown
timestamp: June 27, 2014, 02:49:35 pm
content: You can use attiny24 if want to keep low voltage ISP, It is very cheap and have 14 pins.

author: m.m.m
author_rank: Regular Contributor
timestamp: June 27, 2014, 03:32:34 pm
content: thank you both, nope I want to use this chip because of low pin count. can I add my desired code to the beginning of the program before the while (1) loop (for example send "turn off the first light" command) and connect the switch to ground in order to reset the chip whenever the switch is pressed and when is resets it restarts the whole program from the beginning and so turns it off?I also won't replace the batteries much.

author: XOIIO
author_rank: Super Contributor
timestamp: June 27, 2014, 03:47:02 pm
content: Quote from: m.m.m on June 27, 2014, 03:32:34 pmYes, reset is basically a power cycle for the chip.

author: jlmoon
author_rank: Unknown
timestamp: June 27, 2014, 03:55:08 pm
content: Microchip makes some small footprint parts that you can wiggle a pin tied to INT0 and it will wake the chip out of deep sleep mode, the 24F part comes to mind (current is nill in this mode) and then it will execute code within your wake up blocks.seehttp://ww1.microchip.com/downloads/en/DeviceDoc/39727a.pdffor the details..
Reset Pins on Counter IC - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: July 18, 2019, 11:41:45 am
content: Hi,I was wondering why there are two reset pins gated together on this IC. Wouldn't one reset pin be enough?https://www.ti.com/lit/ds/symlink/sn54ls93.pdfThanks,Carl

author: Gyro
author_rank: Super Contributor
timestamp: July 18, 2019, 12:56:31 pm
content: It enables you to tie them to the binary outputs to achieve different divide ratios (among other things).

author: kosine
author_rank: Regular Contributor
timestamp: July 18, 2019, 01:00:59 pm
content: Pinout looks the same as the 74LS93, some explanation is given on this page:http://electronicsclub.info/74series.htm"The counter is in two sections: clockA-QA and clockB-QB-QC-QD. For normal use connect QA to clockB to link the two sections, and connect the external clock signal to clockA.For normal operation at least one reset0 input should be low, making both high resets the counter to zero (0000, QA-QD low).Counting to less than the maximum (9 or 15) can be achieved by connecting the appropriate output(s) to the two reset0 inputs. If only one reset input is required the two inputs can be connected together. For example: to count 0 to 8 connect QA (1) and QD (to the reset inputs."

author: eev_carl
author_rank: Regular Contributor
timestamp: July 19, 2019, 11:41:28 am
content: Thanks for the link. It seems like these move in tandem for the reset function. Why not just one pin to bring the signal low like in a 555?Plugging Qb and Qd into the two resets turns the counter to a decade counter.
Reset signal - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: January 18, 2021, 06:25:24 am
content: When I need a reset signal, I usually use an RC (+ reverse diode in parallel with the R for fast discharge) and a schmitt trigger gate.Are there specially made ICs?Would it make sense to use a paduk microcontroller? Using a microcontroller seems an overkill, but at their price it'd be cheaper!

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: January 18, 2021, 07:01:02 am
content: Yes, please search for "reset supervisor" or just "supervisor". TI makes a number of them, eg: TLV840. Sometimes you can find them embedded in LDOs or buck converters.

author: fabiodl
author_rank: Frequent Contributor
timestamp: January 18, 2021, 10:20:03 am
content: Thanks, this is exactly what I was looking for

author: fabiodl
author_rank: Frequent Contributor
timestamp: February 15, 2021, 09:31:52 am
content: I need to add a manual reset signal as well. The TLV840M provides an input for such requirement.I would however be tempted to use this ICIMP809because it is way cheaper.Would the following configuration be ok(schematic in the attachment)?Does the pullup create problems, for instance in correctly measuring the voltage to the point it keeps resetting?The chip reports a current of 15uA, so I'd guess a 0.07V should not be a problem if the connected peripherals do not draw too much current

author: fabiodl
author_rank: Frequent Contributor
timestamp: February 15, 2021, 10:02:03 am
content: Sorry for self-replying, In case someone else has the same requirements I leave it for posterity.I found out the max811 and clones have the manual reset pin input,I'll go with that

author: S. Petrukhin
author_rank: Super Contributor
timestamp: February 15, 2021, 11:35:09 am
content: I use this scheme:
Residual-current device - Page 1
Forum section: electronics / beginners

author: bonzer
author_rank: Regular Contributor
timestamp: March 04, 2020, 01:36:15 pm
content: Hello everybody! Sorry if my question sounds too stupid but it's first time I study about this. I'm not interested in all the details about this type of interrupters but only some aspects. I know they are mainly designed for protection, to react for accidental human contact. Is it the only reason it is used? I mean humans make the current go to the ground so phase and neutral currents become different (enough) and this principle is used to make the attached schematic work. Meanwhile if we have an internal short circuit that isn't touched by human but is danerous for my device, it doesn't react in theory because those windings combined like that are transparent to differential currents equal in norm so it protects only human or from any other phase to ground contact but not from phase to neutral. To protect my device I should use a fuse or anyway a different structure for my current interrupter. Am I right?

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2020, 01:50:32 pm
content: If there's a short between phase and the earthed case, then it will protect the device, but you're right, a fuse is required to protect against fire from phase to phase or neutral overloads.Also note that a fuse isn't there to protect the appliance, but the cable. There are few things which are capable of protecting semiconductors inside the device. Slow blow breakers/fuses can protect motors from over-current and thermal fuses/bimetal strips can protect against overheating and fire.
Resistance Emulator Circuit Help - Page 1
Forum section: electronics / beginners

author: EEV FTW
author_rank: Newbie
timestamp: March 30, 2018, 02:04:33 am
content: I need some suggestion on the easiest way to either buy or build a circuit resistance emulator that output a resistance range of say 58k and 64k ohms. The circuit can't have a fixed resistance so it needs to vary. As far as the frequency of this changing, well faster than 1 hz.I was thinking of an LM555 timer or something along those lines, but figure someone here new of an easy way to do it with some cheap passive components (resistors, caps, ect). I'd like the circuit to run on say 20v so headroom of maybe 25 volts. I however can always buy a cheap dc buck converter to drop voltage if it helps circuit design.
Resistance is Futile  - Page 1
Forum section: electronics / beginners

author: nick.sek
author_rank: Regular Contributor
timestamp: May 19, 2012, 08:36:30 pm
content: Hey everybody, Just wanted to share the link for my new video -which goes over the struggles of students and there studies.Hopefully you enjoy it, and thanks for the support last week it meant a lot to me!This week's Episode:Last Week's Episode:Why I got into Electrical Engineering

author: IanB
author_rank: Super Contributor
timestamp: May 19, 2012, 09:19:54 pm
content: Thereis just a little typo that you might want to fix in your first sentence, by the way...Now I shall watch the video

author: nick.sek
author_rank: Regular Contributor
timestamp: May 21, 2012, 02:36:07 am
content: IanB, not only do you help me with my struggles in becoming an engineer but as a student in general! (Thanks for all your help)
Resistance measurement of a resistor parallel to a capacitor - Page 1
Forum section: electronics / beginners

author: nivek
author_rank: Contributor
timestamp: November 26, 2013, 08:50:47 pm
content: I apologize if this is a stupid question, just looking to clarify things in my understanding.I am trying to take a resistance measurement of a resistor, to see if it is still within spec or not. In this case, the resistor is installed parallel to a 47uf capacitor. In this case, it the resistor runs from the point attaching the positive side of the cap, and runs to the shared ground (Point-to-point wiring). What I am wondering is, will this capacitor's presence effect my resistance measurement? My initial thought is yes, as it would be "charging up", and using some of the current that the meter is putting out to measure the resistance.My thinking is this could cause the multi-meter to read low in this case (Until the capacitor theoretically became fully charged?) Am I completely off-base on this?

author: IanB
author_rank: Super Contributor
timestamp: November 26, 2013, 08:56:08 pm
content: Multimeters usually measure resistance by passing a constant current through the resistor and then measuring the voltage difference across the resistor. So if you wait until the reading has stabilized (when the capacitor is charged up) then the resistance reading should be accurate. (However, any leakage current through the capacitor could affect the resistance reading.)

author: nivek
author_rank: Contributor
timestamp: November 27, 2013, 01:38:43 am
content: Makes sense, thanks!

author: owiecc
author_rank: Frequent Contributor
timestamp: November 27, 2013, 08:11:29 am
content: You say it is installed parallel to a cap. What about other components? Isn't this RC connected to anything else? Measuring any components in circuit is very tricky.
resistance of different transformer windings? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: March 13, 2014, 02:00:06 am
content: I have this transformer from an old stereo that seems to have 3 secondaries. They're completely independent of each other too.The bleu-blue and red-red wires both connected to the circuit board to little B20S rectifiers plus each a single large-ish 25V cap and the Orange-White-Orange connected to a larger 205N rectifier and two 3300uF 35V caps so obviously the different parts of this system had different power requirements (tape, radio, turntable, amp etc.).Checking the AC voltage with my meter I getRED = 14.6VBLUE = 15.25Vorange-white-orange = around 17V per sideQuestion?I checked the resistance between the different windings and RED = 0.7ohm, BLUE = 1.2ohm, ORANGE-WHITE-ORANGE = 0.5ohm on each side of the center tap (so 1ohm total)Can the resistance tell me anything about this transformer?Why would the blue one be higher than the others?Even though it's a rather large thing, it's really 3 smaller windings in one package so would this mean that it's not as capable a transformer as something that just has ONE large secondary?

author: IanB
author_rank: Super Contributor
timestamp: March 13, 2014, 02:08:22 am
content: The resistances will tell you about the thickness of the wire used in the secondaries, and therefore about how much current each was designed to supply. Given that they all produce about the same voltage (and thus have a similar number of turns), you can assume to a first approximation that the available current is in inverse proportion to the resistance. So a 0.5 ohm winding can provide more than twice as much current as a 1.2 ohm winding.

author: dentaku
author_rank: Frequent Contributor
timestamp: March 13, 2014, 02:57:24 am
content: Quote from: IanB on March 13, 2014, 02:08:22 amGreat. At least it's just the blue one that measures higher than the others because it's the orange and white center tapped one that I'm interested in.I built an LM317 circuit on a breadboard and it supplies me with voltages high enough for what I need it for.I'm not sure how to test how much current the transformer is able to safely supply but I'm assuming it's more than the 1.5A the LM317/337 is rated for anyway.
Resistance reading - Page 1
Forum section: electronics / beginners

author: fixit7
author_rank: Regular Contributor
timestamp: May 16, 2019, 08:22:23 pm
content: I got a .50 reading for resistance using the 2K scale.Does that translate to 500 ohms?

author: magic
author_rank: Super Contributor
timestamp: May 16, 2019, 09:05:57 pm
content: Why won't you just test it with a known resistor?Probably it's 0.5k indeed.

author: fixit7
author_rank: Regular Contributor
timestamp: May 16, 2019, 09:12:12 pm
content: Thanks, I did not think of that.Yes it was 500 ohms.
Resistance seen by a capacitator - Page 1
Forum section: electronics / beginners

author: nikidi1992
author_rank: Newbie
timestamp: January 01, 2016, 02:06:23 pm
content: Do you know of any website or text that helps with explaining the resistence seen by a capacitator and if the capacitators are indipendent or not

author: Simon
author_rank: Unknown
timestamp: January 01, 2016, 02:07:38 pm
content: Are you refering to calculating the reactance of a capacitor ? you need to provide more information for us to help you
Resister sip network? - Page 1
Forum section: electronics / beginners

author: snipersquad100
author_rank: Frequent Contributor
timestamp: January 09, 2018, 09:57:25 am
content: Can anyone explain whats going on in this circuit concerning the 10k sip? It doesn't look right to me, why would the common pin be connected to VCC and connected to the pins on the 8515, that would just keep all the pins high all the time.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: January 09, 2018, 10:09:56 am
content: It's a pullup. It weakly pulls the UDN2981's inputs high in case the ATMega isn't pulling them low. For example, in RESET and until defined as an output, the PA0-7 pins are defined as inputs. This means they won't necessarily drive the UDN2981 inputs reliably during this time.

author: Yansi
author_rank: Super Contributor
timestamp: January 09, 2018, 10:27:39 am
content: No, that is not true.The pullups are there due to the fact that mega8515 is a direct pin compatible replacement for 8051 MCU. The 8051 MCU does NOT have integrated pullups on port P0 (the port A on the atmega). The 8051 P0 is only open collector outputs.However the schematic is still wrong, as the 10k pullups arenot enoughto drive the UDN2981, neither are the integrated ~50k pullups for the low side driver.As the Atmega has configurable symetrically driven totem-pole output stages, the pullups are pointless and shall be pull-DOWN instead to ensure it won't be lit whenever the MCU pins are floating high impedance. However the drivers already have pulldown resistors built in.Therefore when done properly, the drivers shall be isolated from an 8051 device using octal buffers like 74245. With the atmega MCU, it is fine as it is, if one replaces he pullup with a pulldown array.

author: snipersquad100
author_rank: Frequent Contributor
timestamp: January 09, 2018, 01:00:31 pm
content: Any chance you could draw a better schematic???

author: Paul Moir
author_rank: Frequent Contributor
timestamp: January 09, 2018, 10:15:13 pm
content: Quote from: Yansi on January 09, 2018, 10:27:39 amThanks, I admit this is a case of TLDRtD (Too Lazy, Didn't Read the Datasheets).
Resistive load for testing - Page 1
Forum section: electronics / beginners

author: sureshot
author_rank: Regular Contributor
timestamp: April 25, 2018, 08:03:28 pm
content: I was looking to put together a cheap and cheerful resistive testing load, using 50 watt power resistors. 6 x 2.7 ohm resistors, so just over 300 watts. I would plan to switch in 50 watt increments up to the maximum value.And I would use forced air cooled cpu heatsink, that can handle 150 watts each. So using two heatsink. Using relays to switch the loads in and out.Can anyone see anything wrong with this idea, it's not critical for tolerances or presicion, more a quick testing load instead of using halogen lamps as I've been doing.Thanks for reading, any feedback appreciated.

author: Jwillis
author_rank: Super Contributor
timestamp: April 26, 2018, 04:37:58 am
content: Really dependent on how many amps and volts you plan on pounding into those resistors.You can max the wattage of one of them with only 4 amps.You can use the chart below to figure out what your requirements are.

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: April 26, 2018, 05:39:05 am
content: Why not use lamps? I often use car lamps, 5W, 12W, 21W, 50W, 75W and 100W bulbs. They are made to handle the power and have PTC resistance kinda self regulating. Yes the load is slightly inductive.FWIW.

author: MosherIV
author_rank: Super Contributor
timestamp: April 26, 2018, 06:29:50 am
content: Need to check the relays can handle the current for the max power through the resistors.

author: sureshot
author_rank: Regular Contributor
timestamp: April 26, 2018, 09:50:59 am
content: Thank you for your replys. I've used lamps for a while up to 500 watts, there kind of all over the place strung together in parallel. The resistor idea was going to use an enclosure with meters. I had in mind 6 x 50 watt 2.7R power resistors, switched with 40 Amp automotive relays via a toggle switch on the relay coils.I'm thinking 2.7R is a bit restrictive for really just around 12 Volt testing. Its converted server power supplies i would be mainly testing. Having thought about it...6x 3.9R would give a better range from 12 - 14 Volts testing. Around 200 watts at 12 Volts and closer to 300 Watts at the 14 Volt level.I don't think 2.7R resistor coyld handle the 12 - 14 Volt Range.

author: Brumby
author_rank: Unknown
timestamp: April 26, 2018, 10:50:49 am
content: Doing power calculations can give you answers...At 12 V, a 2.7 Ω resistor will dissipate 53.3 WAt 14 V, a 2.7 Ω resistor will dissipate 72.6 WAt 14 V, a 3.9 Ω resistor will dissipate 50.3 WAt 14 V, a 4.7 Ω resistor will dissipate 41.7 W

author: sureshot
author_rank: Regular Contributor
timestamp: April 26, 2018, 06:43:12 pm
content: Yes I realised 2.7R is to close, and restricts the voltage I can test at. 3.9R is a bit better, although I will be a little off the 50 watts I'm after from each resistor.So 3.9R it will be, the cooling is adiqute for the load power.