hybridfree/eevblog-posts huggingface dataset:
Need help in finding BBSRAM replacement (decoding & comparing two datasheets) - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: April 04, 2013, 01:24:04 am
content: Currently I'm looking for a possibility of a drop in replacement for the BBSRAM made by Maxim/Dallas DS1225Y with a F-RAM based memory made by Ramtron (Cypress Semi) FM1608-120-PG.Both datasheets are attached below at this post.I've checked both are pins compatible, also at the basic specification like the voltage rating and other basic operating conditions, its just I'm totally lost when it comes to comparing both at the AC timings and the logic conditions like for read or write activities.I tried but still quite hard for me to make a conclusion if this F-RAM is suitable , also to be honest I'm kind of worry if I missed crucial details as Dave loves to say "trap for young player".Appreciate any helps, thanks in advance.

author: BravoV
author_rank: Super Contributor
timestamp: April 05, 2013, 01:32:49 am
content: Damn, finally found it myself, apparently this cool F-RAM just can't be plugged in to replace the pesky BBSRAM.The DS1225Y only needs the Chip Enable (CE) pin to be enabled "once" for multiple read/write operations, while the FM1608 needs the CE to be "toggled" for every read/write, the memory address changed and latched on CE 's edge, not the state, what a bummer.

author: amyk
author_rank: Super Contributor
timestamp: April 05, 2013, 11:31:19 am
content: Have you looked at the STK12C68?

author: BravoV
author_rank: Super Contributor
timestamp: April 06, 2013, 06:07:07 am
content: Quote from: amyk on April 05, 2013, 11:31:19 amYes, I've looked into that as well, but worry the complication on the Autostore feature at power up or down sequence.Anyway, I've pulled the trigger on FM28V020-SG at Cypress Semi's store, after an intense reading and comparing them, even its 4 times bigger (32Kx8) vs (8Kx8), I'm planning to make a SOIC 28 to DIP adapter with a small DIP switch with 2 poles, soldered at the adapter for manually switching between 4 banks.Theoretically, this should last for centuries.PS : This thread actually related to my other thread ->Here
Need help in finding replacement capacitor for Pfaff 332 sewingmachine foot. - Page 1
Forum section: electronics / beginners

author: ErikS
author_rank: Newbie
timestamp: April 15, 2024, 10:49:25 am
content: My sewingmachine (Pfaff Model 332-260) suddenly started to continue running even with the pedal not pressed down. I took it apart and it seems that the capacitor is shorted, allowing current to always run through. The Info on the cap: EROID 0,05µF 250V~ -55*/+105* F1174PI have a donor machine of a slightly newer variant, but it has some extra components in the foot, though a similar capacitor. The info on that cap is: Typ 9748 sp 2 5 MHz 250V~ -20* +100* 0,05µF + 1,8MΩ (+a diagram of a cap and resistor in parallel)Could I use the donor capacitor? Or is it just better to buy a new one? In that case, what would be a good replacement? Note that the input voltage is 230V AC.

author: tunk
author_rank: Super Contributor
timestamp: April 15, 2024, 11:11:07 am
content: I had the same problem a couple of weeks ago with a Bernette sewingmachine (plus smelly magic smoke). It was a Rifa 0.1uF 250V~ X capacitor.Replaced with a salvaged 0.1uF 250V~ X2 capacitor. If it's across 230V,then I think it should be a X2 safety capacitor.

author: BeBuLamar
author_rank: Super Contributor
timestamp: April 15, 2024, 11:44:03 am
content: I think it would work fine if you simply remove the capacitor. But I would buy an new cap to replace.

author: ErikS
author_rank: Newbie
timestamp: April 15, 2024, 11:50:25 am
content: Quote from: BeBuLamar on April 15, 2024, 11:44:03 amThat reminds me I dont know what the cap does in this circuit. What does it do? From what I see it is shorted as soon as the pedal is pressed down one "step". (I dont know a lot about electronics btw)

author: BeBuLamar
author_rank: Super Contributor
timestamp: April 15, 2024, 11:53:58 am
content: I think it's a snubber to suppress the arcing when you release the pedal.
Need Help in Verification of PCB Design - Page 1
Forum section: electronics / beginners

author: paulcanon
author_rank: Newbie
timestamp: August 19, 2020, 02:38:23 pm
content: Hello All,i have started working on a IOT project and i have designed a Energy meter based on MCP39F511A IC from Microchip, i have followed their reference schematic and designed PCB based on only what i require. i have attached the schematic as well as PCB design and also the reference schematic, the problem im facing is, in refence design they have connected the Analog ground (Neutral in case of AC) to the Digital ground. it would be helpful if any of you can validate the PCB design.Thanks and RegardsPaul Canon
Need help interpreting current rating of LDO in datasheet - Page 1
Forum section: electronics / beginners

author: Jim from Chicago
author_rank: Regular Contributor
timestamp: October 04, 2021, 03:24:41 pm
content: LDO Datasheet:https://www.mouser.com/datasheet/2/308/1/NCP705_D-2317255.pdfThis LDO has a nominal output current of 500mA. Does this mean that it will always try to output 500mA? Or is this 500mA just the capability of the device, and it will only output however much current the thing its connected to wants to draw? I think it's the latter, but I just want to confirm this.

author: madires
author_rank: Super Contributor
timestamp: October 04, 2021, 03:37:03 pm
content: Yep, it's the latter. The LDO regulates the voltage, not the current.

author: Jwillis
author_rank: Super Contributor
timestamp: October 04, 2021, 03:42:10 pm
content: Note 5 Characterized when VOUTfalls 100 mV below the regulated voltage at VIN= VOUT(NOM) + 0.5 V.The chip is capable of more current but drawing more current effects the Voltage regulation .It sometimes called derating .

author: Jim from Chicago
author_rank: Regular Contributor
timestamp: October 04, 2021, 05:13:20 pm
content: Thank you
Solved: LED RGB led strip controller (odd blinking) - Page 1
Forum section: electronics / beginners

author: Wannes
author_rank: Newbie
timestamp: August 15, 2013, 01:25:16 pm
content: Hello,I made a controller for a RGB led strip, using 555 PWM circuit.schematic:https://www.dropbox.com/s/9usml232wdu96r5/Schematic%20RGB%20led%20strip%20controller.JPGIf I test each color control, it works as intended. But when i make a color combination, a odd flickering/blinking (fast, visible) appears. If i turn each color to the maximum the flickering disappears.Please help,Greetings Wannes

author: David_AVD
author_rank: Super Contributor
timestamp: August 15, 2013, 10:06:29 pm
content: As a pure guess, I'd say that your power (+12 and 0V) wiring is too thin or is routed in such a way that the LED current is affecting the PWM oscillators supply.

author: hlavac
author_rank: Frequent Contributor
timestamp: August 17, 2013, 10:50:08 am
content: You probably have problem with interference (the 555 frequencies are slightly different thus the relative phase is shifting) in combination with power supply that can not handle all three colors on at the same time (drops voltage).Try adding a beefy capacitor to your power supply input.Or change the design slightly to synchronize the phases of the PWM color channels.That way while it still suffers from the power supply sagging it will not blink.

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 17, 2013, 12:43:18 pm
content: I agree with the others that it sounds like a power supply issue but you might swap the 100nF cap on the trigger and threshold pins to one with a smaller value (22nF or 47nF, for example) to increase the PWM frequency. It is at about 120Hz now--whichshouldbe okay--but a higher frequency obviously won't hurt (to a point) and is an easy change to make to see if it is a factor or not.

author: Wannes
author_rank: Newbie
timestamp: August 27, 2013, 08:29:14 am
content: Problem Solved!Thanks for the help.Solved it by using a different capacitor (pwm freq.) for each color (100 nF 68nF 47 nF),Wannes
Need help looking for my next project - Page 1
Forum section: electronics / beginners

author: blewisjr
author_rank: Frequent Contributor
timestamp: July 11, 2013, 12:22:21 pm
content: Hello everyone,It has been a while since I posted. I am currently wrapping up my alarm clock project. Just a few more sync bugs to squash out after a small hiatus from the project. So now I am starting to look towards my next project to step up my learning even more. The alarm clock was a great learning experience for me and I learned a lot about PIC micro development in the process. I must say I think I am going to stick with the 8 bit PIC's for a while. The new XC8 compiler sports a nice 10% reduction in free mode code size making it much more manageable.So I am looking for my next project for the 8 bit PIC any suggestions as to what would be a good next step up from the Alarm Clock?

author: deephaven
author_rank: Frequent Contributor
timestamp: July 11, 2013, 12:27:05 pm
content: Propeller clock?

author: madires
author_rank: Super Contributor
timestamp: July 11, 2013, 12:59:52 pm
content: The PIC version of the Transistor Tester?
Need help purchasing cables - Page 1
Forum section: electronics / beginners

author: triwheeler
author_rank: Newbie
timestamp: June 04, 2014, 11:18:56 pm
content: I'm very new to doing anything with electronics so forgive the lack of nomenclature. I have a circuit bending project and I want to draw out all the connections that I've soldered to one device and bring them into a separate project box. Its all low current signal stuff.Does anybody have any suggestions on how to do this? There will probably be 20-30 different wires. I was thinking about heat shrinking a bunch of wires together but I'm worried it wouldn't be so durable.. afraid if the cable was tugged too hard one of the individual connections inside the device I'm modifying would come lose.Is there some kind of multi-cable with a header or something that i can set into both the original device and the project box to plug a cable into?Does this make any sense?

author: katzohki
author_rank: Frequent Contributor
timestamp: June 04, 2014, 11:30:56 pm
content: Ribbon cable is great for this kind of stuff. You can get the rainbow kind for color coding as well. It's always handy to have some around, just pull off any extra conductors you don't need. And yes, there are connectors specifically for these.Some with connectors:http://www.digikey.com/product-search/en/cable-assemblies/d-sub-cables/1573638?k=ribbon%20cableLots more:http://www.digikey.com/product-search/en?pv321=116&FV=fff40018%2Cfff8020f&k=ribbon+cable&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25
Need help reading transistor datasheet - Page 1
Forum section: electronics / beginners

author: robvanderveer
author_rank: Newbie
timestamp: January 12, 2014, 11:18:53 am
content: I was working on a project and found that an arduino signal through a 100k ohm resistor does not fully saturate my bc547 npn transistor, but a 1k resistor does.Where in the datasheet can i find the info that tells me to use the correct resistor to drive the base of the transistor?Edit: add link to datasheethttp://www.nxp.com/documents/data_sheet/BC847_BC547_SER.pdf

author: mariush
author_rank: Super Contributor
timestamp: January 12, 2014, 11:26:42 am
content: Determine the hFe of the transistor, then you can do the math.This video explains very well how to determine the resistor value:ps. Considering the transistor is 100mA max and the minimal typical hFe is 180 and the minimum hFe being 110, I would do the math for 1 mA going to the base.

author: KJDS
author_rank: Super Contributor
timestamp: January 12, 2014, 11:28:46 am
content: The parameter you need is Hfe and then use ohms law.So if the Arduino drives 5V and there is 0.7V on the transistor base, then that's 4.3V across the resistor. 100k resistor allows 43uA through, with a Hfe of 100 then that's 4.3mA of collector current. If you have a 10k in the base, you'll 43mA.

author: lewis
author_rank: Frequent Contributor
timestamp: January 12, 2014, 11:49:57 am
content: And because hfe varies widely with temperature, age, voltage, between identical transistors from the same batch and by phase of the moon, you'll want to half the resistor value calculated by the maths for reliable operation.Or, if the datasheet specifies a range of hfe, use the lower number to calculate the base resistor the reduce it further by 20%.

author: robvanderveer
author_rank: Newbie
timestamp: January 12, 2014, 11:52:02 am
content: Awesome! Thank you for explaining. Excellent video btw.

author: qno
author_rank: Frequent Contributor
timestamp: January 12, 2014, 02:16:02 pm
content: If you want to drive the transistor in saturation the situation changes.In saturation Vce is about 0.1 volt.With a grounded emitter this means the collector voltage is 0.1V.Your base is 0.7 volt.This means a part of your base current will leak to the collector and not contribute to the drive of the transistor.A rule of thumb is to use 10 times the base current you need for the collector current when calculating with the lowest HFE from the datasheet.One of the appendixes in The Art of Electronics discribes saturation in detail.
NEED HELP rf wireless oscillating electromagnet - Page 1
Forum section: electronics / beginners

author: jhelzer10
author_rank: Newbie
timestamp: June 23, 2018, 09:28:15 pm
content: Hello, i am new to electronics. I have a basic knowledge of electronic components and how they work. But i lack the knowledge of calculations and applying the right components with propper values.I have constructed a wireless oscilating electromagnet. Im using a 9v 555 pulse module to send data to a 433mhz rf transmitter. I have got this end of the circuit to function quite well. But the recieiving end not so much. The 433mhz receiver is 5v. So im using a 7805 voltage regulator to step down voltage from 9v battery. Then the data from the receiver is connected to a 1k ohm resistor then to the base of a tip120 darlington transistor. The reason im using a darlington is because i want as much current as possible flowing through the EM coil. Everything works i just have a few issues. I cant get a full range of adjustment of frequency with the 555 pulse module. Im not getting enough current through the coil. Sometimes the darlington transistor gets hot. And the permanent magnet and the EM coil make this god awful screetching noise when its pulsing. It sounds like a tuning fork and i can actually feel the permanent magnet vibrating at high frequency. Ive tried hooking up more 9v batteries in parralell to boost the current but then i have problems with overheating the transistor. I was under the impression that a transistor acts as an amplifier as well as a switch. So why is it that when i hook the EM coil directly the the batteries i get the amount of current i want. But when the EM coil in wired in the pulsing circuit with the same amount of batteries the strength of EM field is less? Shouldnt the darlington transistor amplify the current? I know there is alot that im missing. Would really appreciate any help i can get. Thanks!

author: Yansi
author_rank: Super Contributor
timestamp: June 23, 2018, 10:05:10 pm
content: Please start here:https://www.elprocus.com/freewheeling-or-flyback-diode-circuit-working-functions/Might help quite some bit.
Need help simulating an SCR in Simetrix - Page 1
Forum section: electronics / beginners

author: samadamsuk
author_rank: Newbie
timestamp: July 24, 2020, 02:14:52 pm
content: Hi All,I'm a complete newbie and I'm trying to simulate this circuit (http://www.zen22142.zen.co.uk/ronj/cots.html) in Simetrix, however as you'll see there's an SCR called TY1 and 'm unable to find either an SCR, a thyristor, or even a user defined part to do this.Any help massively appreciated.Samos
Need help sorting transistors - Page 1
Forum section: electronics / beginners

author: Cliff Matthews
author_rank: Unknown
timestamp: April 22, 2015, 09:43:19 pm
content: How should I categorize extra transistor stock - some of which are unsearchable or Jantx 1980's new-old stock?I bought a component tester to solve the problem (at least maybe..) from ebay (seller 1984yht888)So far, I'm sorting the TO92's and the bulk are NPN's I've put in 4 hfe groups:under 100100 to 400400 to 800over 800The component tester seems to be helpful, except uni-junction devices just show up as 2 diodes with fb drops over 1.2 volts.So I guess there's about 2000 devices to test - I just need pointers on organizing... and should I toss glob-tops with under 40 hfe?

author: Whales
author_rank: Super Contributor
timestamp: April 22, 2015, 09:50:32 pm
content: High-current transistors tend to have lower gains. Keep what you think will suit you -- if you can't find details on a device and you only have one of two, they're probably not much more than a curiosity.

author: Cliff Matthews
author_rank: Unknown
timestamp: April 22, 2015, 09:50:53 pm
content: A few more photos (to show the size of the job)

author: Cliff Matthews
author_rank: Unknown
timestamp: April 22, 2015, 10:00:19 pm
content: Quote from: Whales on April 22, 2015, 09:50:32 pmIs it a good idea to consider small, unknown transistors with really low-gain untrustworthy above 30v and useless beyond 1Mhz?

author: Cliff Matthews
author_rank: Unknown
timestamp: April 24, 2015, 07:22:46 pm
content: Finished! FWIW, it took about 5 hrs to test and sort averaging maybe 5 per minute (between breaks, and curious PDF lookups).I trashed older small NPN's with hfe under 20 and the ZIF looks beat-up, but it still works fine - a good ebay purchase in all.Post note: My dollar store 9v battery still has lots of life left, so eating batteries is not a concern.
Need help sourcing replacement capacitors in Australia - Page 1
Forum section: electronics / beginners

author: StarkRG
author_rank: Newbie
timestamp: May 07, 2019, 11:59:07 am
content: So I'm in the middle of restoring a couple of old Macs (a Powerbook 180c and a Mac 512ke). I've gone through and figured out which capacitors I needed, however when I went on to digikey to order them the shipping cost ended up being about the same as all of the capacitors I was buying (about $20). I'd rather not have to spend twice as much if I can at all help it. Of course, it doesn't help that I'm trying to buy in extremely low quantities (I think the most of any given item I need is six). Is there a source that ships to Australia for less than $20?

author: jeremy
author_rank: Super Contributor
timestamp: May 07, 2019, 12:05:55 pm
content: RS is the only one that will ship for free. element14 is $45 min for free shipping, digikey and mouser are $60 for free shipping.

author: digsys
author_rank: Unknown
timestamp: May 07, 2019, 12:49:36 pm
content: If you list the part details, someone may know where to find them locally.

author: beanflying
author_rank: Super Contributor
timestamp: May 07, 2019, 12:56:36 pm
content: Depending on how much SMD stuff you do or are likely to do Sample Books of components are not a bad way to go for passives at least. Add to them some small quantities of common ones when you are ordering from the usual named suspects works well for me.eBay auction: #132947942629Not a seller recommendation just a starting point and there is plenty of sellers.Through hole Capswww.rockby.com.auare a good mob.
need help testing if a water pump it fulty - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: December 09, 2014, 07:11:12 pm
content: I think the water pump my be faulty in my washing machine (as its not draining)I have removed the pump and done a continuity test on the two terminal and not getting a beep.(as in this instructional video)But, I'm getting a reading of 200ohm, so it not an open circuit?Any advice would be really appreciated, before I start ordering parts.

author: SeanB
author_rank: Super Contributor
timestamp: December 09, 2014, 07:29:08 pm
content: DC resistance will be around 200r, so it probably will not show continuity, but resistance. Most common fault is that the coil is fine but the magnetic impeller inside is worn and sticks in the housing. The coil, magnet and impeller are available as a spare part on their own, and just are a few screws ( 6IIRC) to remove and replace on the housing. There is a o ring seal that you need that will come with it, lubricate the seal with some soapy water to get it to fit, and put together.The kit cost me $15 last time I got one earlier this year, it fits a lot of washing machines.

author: peps1
author_rank: Regular Contributor
timestamp: December 09, 2014, 07:44:20 pm
content: just borrowed a variac to test the pump.....works fine.......now time to double check for blockages.

author: SeanB
author_rank: Super Contributor
timestamp: December 10, 2014, 06:22:59 pm
content: It might turn with no load or dry but with a head of water it will stall. If there is no blockage and the filter is clear with no coins in the piping or the rubber lines the replacement pump is needed. They tend to fail at around the 10000 wash mark, or after around 5 years.

author: BillyD
author_rank: Regular Contributor
timestamp: December 11, 2014, 01:00:25 am
content: Are you sure it's the pump? It's starting to sound like the problem is elsewhere. Does the machine stop and basically wait indefinitely for the drum to empty, which never happens?Anyway the things I would check include:- continuity of wiring from the controller to the switch- the water level switch, i.e. it may be incorrectly indicating that there is no water in the machine. Typically in a washing machine this consists of a diaphram switch triggered by a pressure hose connected to a low part of the plumbing, and is a fairly frequent point of failure.- the controller. It may have a burned out contact or relay.
Need help to find and buy a specific transistor - Page 1
Forum section: electronics / beginners

author: jotwerde
author_rank: Contributor
timestamp: July 19, 2018, 03:21:28 pm
content: Good day,As the title indicates I'm looking to buy a transistor online.Its package is an SOT-223 and it mostly looks like this (the F339 is written on the very bottom, in real):______________| ST e3|___|| | Z3M |___| | G|___||___|F339 |___|______|___|I figured the manufacturer is ST Microelectronics and it's from the Z3M line of products,but I couldn't figure out which product exactly.Does someone know which transistor (product number) this is and where online I can buy it?Thanks a lot in advance.

author: MasterT
author_rank: Frequent Contributor
timestamp: July 20, 2018, 03:06:14 am
content: Seems triak, 1A 600V, DS:https://www.st.com/content/ccc/resource/technical/document/datasheet/af/ee/c1/7b/df/8a/46/d7/CD00002268.pdf/files/CD00002268.pdf/jcr:content/translations/en.CD00002268.pdfMore to buy:https://www.digikey.ca/product-detail/en/stmicroelectronics/Z0103MN-5AA4/497-6630-2-ND/1040593Another maker:https://media.digikey.com/pdf/Data%20Sheets/ON%20Semiconductor%20PDFs/Z0103_107_109MN.pdf

author: jotwerde
author_rank: Contributor
timestamp: July 20, 2018, 05:41:13 am
content: Quote from: MasterT on July 20, 2018, 03:06:14 amFrom the digikey link I get that the product number is Z0103MN 5AA4, right?But when looking for this specific product at Mouser (was looking for pics to see what's written on the Z0103MN 5AA4), you can see that the stuff written on the Z0103MN 5AA4 does not match what's written on mine:https://eu.mouser.com/ProductDetail/STMicroelectronics/Z0103MN-5AA4?qs=sGAEpiMZZMuAO0%252bGuNbnQuRDQRofIrHFazvmU%252b7zUyo%3dIs that a problem? Does it mean they're not the same?

author: MasterT
author_rank: Frequent Contributor
timestamp: July 20, 2018, 10:44:20 am
content: Pictures are for reference only, don't worry. Info, that you should trust is in the manufacturers data sheet. In this particular case, first link to ST web-site, page 11 table 9 "Ordering information - Markings ". If is is still not clear, the ST customer hot line may be helpful.

author: jotwerde
author_rank: Contributor
timestamp: July 20, 2018, 11:10:05 am
content: OK, got it. Thank you very much for helping me out!
Need help to ID resistor - Page 1
Forum section: electronics / beginners

author: PSD
author_rank: Newbie
timestamp: May 11, 2025, 01:30:41 am
content: i think it's 2k ohm, but the end is buggered, i can't make out the last band(or first??)I see it as red-black-red-?

author: golden_labels
author_rank: Super Contributor
timestamp: May 11, 2025, 02:53:19 am
content: No worries. We all love poorly marked resistors, where you can’t tell which end is which.To my eyes it’s aligned to the left (←), so it will indeed be 4-band marking: red, black, red. 20 · 102= 2 kΩ.The fourth band seems to be very deteriorated gold, so 5%. If that was brown (1%), it would rather be a 5-band resistor: E96 series can’t be covered by 4 bands.If taking photos for color identification, it’s good to take them on white background. Unless it would lead to exposure issues. For example on white sheet of paper. Helps with color balance.What has happened to this poor thing?

author: PSD
author_rank: Newbie
timestamp: May 11, 2025, 03:42:52 am
content: thanks for the info. even in its sad shape it ohms out at 2k, so you're most likely right.this is from a 90's Ford truck ECM, the caps are notorious for failing. looks like they were replaced but I'm guessing the juice leaked on the resistor. the resistor is removed from the board in the picture but it lives under the choke looking thing and left of the blue cap. (or below the blue cap if your picture somehow turned 90 degrees like mine)

author: golden_labels
author_rank: Super Contributor
timestamp: May 11, 2025, 04:07:00 am
content: Looking at the first photo, I thought the brown spot on the right (→) is a piece blown out or burned. It seems just a mark of some kind, or dirt. If it measures 2 kΩ, I’d say it is fine despite all the stuff on the lead.Of course, since you already removed it, just replace with a fresh one. The point I’m trying to make, is that the failure is probably elsewhere. Unless solder joint on this one was the culprit.

author: PSD
author_rank: Newbie
timestamp: May 11, 2025, 04:50:22 am
content: yeah, I was thinking the same thing.I just don't see anything else wrong, will have to inspect it closer.

author: benj38
author_rank: Frequent Contributor
timestamp: May 12, 2025, 09:15:01 pm
content: If you look closely, you will see that the distance between the right-most two color bands in your image is slightly larger than the distance between the two left-most bands. In other words, the right most band is further apart from its neighboring band -- it is more "alone".This extra spacing is a common indicator used by manufacturers to signify that this is the last band, i.e., that you should start reading from the other direction.
Need help to identify a blown up component - Page 1
Forum section: electronics / beginners

author: nilocb
author_rank: Newbie
timestamp: November 13, 2015, 09:34:53 pm
content: Hello everyone, this is my first post in the forum so i would like to use the opportunity to thank Dave for his fantastic job... I've learned so much thanks to his videos, very inspirational !This being said, let's get to the point. I'm trying to repair a friend's car audio system which have been blown up by trying to jump start the car with reverse polarity... I guess it must be a diode or something but unfortunately i can't find any info from the markings. I can clearly identify the ST logo but i haven't been able to find a reference. Here is what i think i read :ST EMFPC451Pictures attached in case of i'm missing something.The car audio system is a Siemens VDO brand CD 70 NAVI for Opel/Vauxhall Astra H.The component fails short and blows the fuse each time power is applied to the unit.Thanks for your help.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 13, 2015, 09:39:57 pm
content: Quite possibly this...http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00000724.pdf

author: nilocb
author_rank: Newbie
timestamp: November 13, 2015, 09:47:49 pm
content: Well... that was fast... that was accurate... and it could have taken years to find this myself !Thanks a lot Richard, I will keep you posted with the results !

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 13, 2015, 10:31:02 pm
content: I just went to the ST Micro website and pasted MFP into the search box.It could have been a lot worse.I wish there were some comprehensive and authoritative central source for cryptic SMD labels.

author: JoeN
author_rank: Frequent Contributor
timestamp: November 14, 2015, 02:21:53 am
content: Quote from: Richard Crowley on November 13, 2015, 10:31:02 pmThis, but not as comprehensive as one might want.http://www.s-manuals.com/smd
Need help to identify a Samsung SMD Transistor - Page 1
Forum section: electronics / beginners

author: Wkar1722
author_rank: Newbie
timestamp: May 09, 2022, 08:40:34 pm
content: I would be more than grateful to anyone who could help me to identify this component.The attached picture is part of the inverter section for Samsung Power Board BN44-00200A, TV model LN52A650A1F. I have circled in Red the transistor I need to identify. I also have attached a picture of the actual board indicating where is mounted this component. Very close to the transistor is the reference (QI802) which is also referenced on the schematic.I don't have the service manual for this board, just schematic diagram.Thank you in advanceBill

author: edavid
author_rank: Super Contributor
timestamp: May 09, 2022, 09:00:59 pm
content: MMBT2907

author: Wkar1722
author_rank: Newbie
timestamp: May 10, 2022, 01:00:41 am
content: Thank you very much
Need help to identify a set of equipments - Page 1
Forum section: electronics / beginners

author: Walter
author_rank: Newbie
timestamp: November 22, 2014, 10:45:18 pm
content: Hello,For a project, I need to identify severals old electronics objects. I've allready found a lot but there I stuck.I've identified a HP 5475A Control Unit and HP 5466A Analog to Digital, but I can't find what is the keyboard at the right.This is a DC to DC converter, but I can't find the mark.Same for this Power Supply.Evans & Sutherland... is someone has ever heard?I think these things are power supplies, may be power regulators, I'm not sure... I don't found much devices with this kind of meters.I have no idea what these things can be...I hope you will be able to help me, and I apologize for the lack of information I have...
Need help to identify an smd Capacitor - Page 1
Forum section: electronics / beginners

author: mr6b
author_rank: Newbie
timestamp: August 15, 2014, 05:32:53 pm
content: Hello FriendsCan someone please help me identify an smd capacitor, what type is this1066K751

author: PioB
author_rank: Regular Contributor
timestamp: August 15, 2014, 05:35:04 pm
content: 106=10 microfaradLooks like a tantalum capacitor

author: mr6b
author_rank: Newbie
timestamp: August 15, 2014, 05:41:34 pm
content: Quote from: PioB on August 15, 2014, 05:35:04 pmThanks but why is 106 = 10uf ?

author: PioB
author_rank: Regular Contributor
timestamp: August 15, 2014, 05:43:34 pm
content: http://highfields-arc.co.uk/constructors/info/capacit.htmhere's an explanation I found off Google

author: PioB
author_rank: Regular Contributor
timestamp: August 15, 2014, 05:47:14 pm
content: The last digit is the exponent. So you have 10*10^6 picofarads

author: mr6b
author_rank: Newbie
timestamp: August 15, 2014, 05:52:11 pm
content: Ahh, Understands now , and second line on the capacitor is Volt , so if I'm correct the cap on the picture is 10uf/6V ?

author: mariush
author_rank: Super Contributor
timestamp: August 15, 2014, 05:56:07 pm
content: No, I don't think it's 6v.It's 10 uF , it's Tantalum. The K in 6K may be short for +/- 10% or the whole "6K" may code for a voltage rating, I can't tell for sure.Be careful because the mark there at the top of the image is the POSITIVE side of the capacitor, contrary to how electrolytic capacitors are marked.Also be careful of the voltage rating, because if the circuit voltage is higher than what this tantalum capacitor can support, it can explode or burn with actual flames, unlike electrolytics which more or less just pop up and make smoke.Some SMD components use that way of writing where the last digit is the number of zeroes .. ex 101 = 100 uF . You may also see something like 2R2 which is 2.2 ohm, another way of writing stuff (because dot may be too small to see)

author: chrisbrown
author_rank: Contributor
timestamp: August 15, 2014, 06:04:25 pm
content: See pg17:http://www.kemet.com/Lists/ProductCatalog/Attachments/254/KEM_T2005_T491.pdf

author: mr6b
author_rank: Newbie
timestamp: August 15, 2014, 06:08:16 pm
content: Quote from: chrisbrown on August 15, 2014, 06:04:25 pmUnderstands , I have a PowerPC card for an Amiga 1200 computer and 1 smd cap got knocked , so i have to replace whit an new cap , the PowerPC card runs on 3.3V,2.5V and 5V so if i get an cap that is rated 10V i will be safe
need help to increase bandwidth using seveal transmitter - Page 1
Forum section: electronics / beginners

author: EP3SK
author_rank: Newbie
timestamp: December 18, 2023, 12:30:17 pm
content: I am study Master of Communication system engineering. I have a question about a system structure. imagine instead of one digital data transmitter like nRF24L01 we used several of it and we split source of data ( divide ) data to several nRF24L01 to achieve more bandwidth . first of all , what is name of this technique? i know it wont be FDM , TDM or CDMA because any of these may used in each of nRF24L01. secondly if you may know any book or article explained this technique please advise it to me.

author: ramussons
author_rank: Contributor
timestamp: December 18, 2023, 02:36:29 pm
content: MCM - Multi Carrier Communication ?http://www.wirelesscommunication.nl/reference/chaptr05/mccdma/mcm1.htm

author: CaptDon
author_rank: Super Contributor
timestamp: December 18, 2023, 02:44:09 pm
content: I should think the answer will be in the texts of your studies? Are you self taught or studying at university? The difficult part is how you want to split the data stream and how you can put it back together again allowing for slightly different time delays (which could also vary with weather) between your two or more signal paths. Some sort of re-syncronizer may be needed at the receive end.

author: David Hess
author_rank: Super Contributor
timestamp: December 18, 2023, 02:49:33 pm
content: Seems like spatial division multiplexing.https://en.wikipedia.org/wiki/Spatial_multiplexing#Wireless_communications

author: EP3SK
author_rank: Newbie
timestamp: December 18, 2023, 03:36:53 pm
content: thanks . I will study it

author: EP3SK
author_rank: Newbie
timestamp: December 18, 2023, 03:40:58 pm
content: I study Communication systems at Semnan University , Iran . according to my tries , Analog device has a system for transmitting HD signals and it is very expensive . the link below :https://www.analog.com/en/education/education-library/videos/5445067129001.htmlthis device will cost over 250 USD , i was thinking instead of using expensive models , use nRF24L01 and divide streams in lower bit rate and combine them at receiver side .

author: EP3SK
author_rank: Newbie
timestamp: December 18, 2023, 04:17:50 pm
content: this link is about a system that multiplex data by itself in different carrier ( or antenna OFDM , TDM , FDM and so on) . but i am not going to interfere modulation process that is handed by for example several nRFL24L01. that means my data before entering to Modulators , is divided to several inputs of different of them that each may have any MOD types itself.
Need help to port a single transistor negative voltage regulator, from -15to-12 - Page 1
Forum section: electronics / beginners

author: workbench
author_rank: Newbie
timestamp: June 07, 2019, 09:23:46 pm
content: I have a schematic for a Negative Voltage Regulator.However, the plan assumes an input voltage of -15V.My power supply delivers only -12V.Can someone tell me which values I have to adjust?I think I have to change the values of R4 and R49. I do not know how to proceed.

author: MarkF
author_rank: Super Contributor
timestamp: June 07, 2019, 09:43:33 pm
content: You are already using a LM7812 regulator for the positive voltage.Just replace all the negative side with a LM7909. Or use a LM7809 and LM7909 for +/-9VDC.

author: workbench
author_rank: Newbie
timestamp: June 07, 2019, 10:16:41 pm
content: That's my plan too.I already ordered some. But they will arrive in a few days.I would like to test the circuit today.All I have here are resistors Zener diodes and transistors.

author: Zero999
author_rank: Super Contributor
timestamp: June 07, 2019, 10:33:54 pm
content: It's not a proper voltage regulator, but a potential divider (R50 & R49) with an emitter follower or buffer transistor (Q13).VOUT= R49*VIN/(R50+R47) - VBEVBEis the base-emitter voltage of the transistor, which will vary from 0.6V unloaded to around 0.8V, when it's passing a decent load current.The above formula gives around 9.4V fully loaded. Changing R50 to 1k8 should give a similar output voltage with 12V in.If you want to use the LM7809, then Q13, R50, R49, R4 and C4 will need to be removed. You might want to consider the LM78L09, which has a lower current limit of 100mA, which might be more suitable, than the 1A offered by the LM7809. Another option is the LM317L, which does require a couple of resistors, but gives better performance than the LM78L09.

author: mikerj
author_rank: Super Contributor
timestamp: June 07, 2019, 10:38:47 pm
content: R4 and R49 form a potential divider, and the transistor provides current gain. This means the output is a fixed fraction of the input so there is no voltage regulation i.e. if the input voltage changes, so will the output.The output voltage can be approximately calculated as follows:Vout = (R49/(R49+R4) * Vin) - VbeVbe is the base-emitter voltage of the transistor, which will be approximately 0.6v. Using the current values:10k/(10k+4k7) * -15 + 0.6 = ~-9.6vIf you aim for the same voltage with a -12v supply you need a divider ratio of:(-9.6-0.6)/-12 = 0.85You could change either or both resistors to achieve this, but you should keep the impedance of the divider similar or lower (impedance=R49 in parallel with R4)e.g. (10K/0.85)-10k = 1.76k so replacing R4 witk a 1.8k resistor would give you a very similar output voltage with -12v supply.Edit: Sorry, a bit late in posting this!

author: workbench
author_rank: Newbie
timestamp: June 07, 2019, 10:50:10 pm
content: thanks for the technical competence
need help to repair my boat - Page 1
Forum section: electronics / beginners

author: jacksole
author_rank: Newbie
timestamp: December 12, 2017, 01:32:57 am
content: Hi guys, IDK, if this is a right place to ask questions. I have a boat, something is wrong. I need a new solenoid valve coil I think. I searched online, find this thing is what I needhttp://www.solenoidsupplier.com/solenoid-actuator-rexroth-switching-solenoid-valves/, but I don't know where to buy it. Does anyone know where to find a dealer near Miami? Thank you guys.

author: nicalitz
author_rank: Regular Contributor
timestamp: December 12, 2017, 06:18:32 pm
content: Might be best to just email/call them and ask is they have any US distributors. From my experience, most Chinese companies would gladly ship to anywhere, so you could try that as well.

author: Belrmar
author_rank: Regular Contributor
timestamp: December 12, 2017, 06:57:31 pm
content: Could you describe your problem a bit better? A bit of context always helps
Need help underderstanding graph. - Page 1
Forum section: electronics / beginners

author: thermal
author_rank: Newbie
timestamp: April 06, 2013, 08:46:28 pm
content: New to using scopemeter. I made a measurement using the Fluke 124 connected to a 9 volt battery. I was expecting the graph line to be straight when connected but it looks looks a little jagged. Can anyone explain why ? Pictures of measurment attached.

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 06, 2013, 09:16:55 pm
content: If you digitize an analog value there will always be a rounding error, that is what you see on the display. And then there is noise, jitter, stability... What you see is perfectly normal.

author: thermal
author_rank: Newbie
timestamp: April 06, 2013, 09:21:39 pm
content: :-//Should I see the same jitter when the battery is not connected?

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 06, 2013, 09:29:53 pm
content: Quote from: thermal on April 06, 2013, 09:21:39 pmThey probably have a circuit that detects when the input is zero and then suppress the jitter.If you look at this official picture from Fluke:you see the same wiggle...

author: thermal
author_rank: Newbie
timestamp: April 06, 2013, 09:38:27 pm
content: How do I determine if the jitter is caused from the scope operation or a problem with circuit being measured ?

author: w2aew
author_rank: Super Contributor
timestamp: April 06, 2013, 10:53:44 pm
content: Quote from: thermal on April 06, 2013, 09:38:27 pmOne way that often works (but not always) is to change the vertical scale to a lower V/div setting. If the noise has the same variation in number of pixels, then it's probably the scope. If the noise occupies more vertical pixels at lower V/div settings, then it's likely your circuit.Averaging can be used to remove noise that is I correlated to the signal.

author: Simon
author_rank: Unknown
timestamp: April 06, 2013, 11:04:56 pm
content: If the scope is unconnected then chances are you will pick up a 50Hz sine wave (or a variation depending on circumstances) that comes from the mains supply, 60Hz if your in the US
Need help understanding a circuit - Page 1
Forum section: electronics / beginners

author: tomy983
author_rank: Contributor
timestamp: November 21, 2017, 09:47:39 pm
content: Hi, I found this instructablehttps://www.instructables.com/id/Multichannel-Wireless-Light-Dimmer/with a circuit for a trailing edge dimmer. I would like to replicate it but instead of two channels I would like to go for 12. I am far from decent so I intend also to post my modified schematics and pcb layout, once about finished.I understood all the working principle, but since I will have 12 channels I would like to optimize a little.This is the original schematic.https://cdn.instructables.com/ORIG/FP6/5RF8/J2MAORX6/FP65RF8J2MAORX6.pdfIn the instructable description the author states that each channel must have its own 12V supply to trigger the mosfets. I can't understand why.Is there a way to have a single 12 or something volts (the mosfets I plan to use hame max Vgs of 25V) supply for all of them?

author: Zero999
author_rank: Super Contributor
timestamp: November 22, 2017, 07:19:27 pm
content: Each MOSFETs must have an isolated 12V supply for the driver, because their sources float at different voltages. A pair of switched off MOSFETs will float at the mains voltage, whilst a pair of switched on MOSFETs will be closed to 0V.

author: tomy983
author_rank: Contributor
timestamp: November 28, 2017, 07:45:09 pm
content: Quote from: Hero999 on November 22, 2017, 07:19:27 pmThank you, it took a while but I understood what was wrong and also looked for a solution. I learnt something about mosfet drivers and also the insulated ones.I finally put down a schematic that I think might work. I also tried to simulate it and looks ok to me.I would like if possible your opinion on drivershttp://www.vishay.com/docs/83469/vom1271t.pdfand mosfetshttps://www.infineon.com/dgdl/Infineon-IPD50R380CE-DS-v02_03-EN.pdf?fileId=db3a30433ecb86d4013ed0a2ef580f38I don't know what to watch out for and read in several places that matching might not be as straightforward..Also I am not sure whether I should put a resistor across the gate driver output or not...To switch the leds of the gate driver I thought I might use a 16 channel constant current led driver, of which I set the current to 30mADoes it look ok?Thank you
Need help understanding a malfunction. VC Resonance Circuit of a VCF - Page 1
Forum section: electronics / beginners

author: workbench
author_rank: Newbie
timestamp: June 09, 2019, 01:01:06 am
content: I made a PCB for a diode ladder filter.The template was the YuSynth EMS clone.My problem now is that the filter is permanently oscillated as if the resonance pot were fully turned on,even if resonance is fully turned to the left.The voltage at the gate terminal of the N channel j-fets is in the correct range between -0.1V and -2.4V.The oscillation stops when I supply a negative voltage at RES-CV input.While the voltage is applied, the Resonace potentiometer behaves normally.I have already tried to reduce R31 to 220k without success.Can someone tell me where the problem lies?I attach the complete schematic in the appendix

author: Audioguru
author_rank: Super Contributor
timestamp: June 09, 2019, 01:34:08 am
content: Your opamp has no power supply so it will do nothing.The datasheet for the 2N3819 Jfet shows that when the gate voltage is only -2.4V then some of them will not turn off. All of them turn off when the gate voltage is -8V.

author: workbench
author_rank: Newbie
timestamp: June 09, 2019, 02:08:28 am
content: The supply for the opamp can be seen in the PDF. it is connected to + 12V and -12V.
Need help understanding a value in a datasheet - Page 1
Forum section: electronics / beginners

author: mattisafur
author_rank: Newbie
timestamp: March 13, 2022, 01:43:47 pm
content: Hi everyone,I'm making a crude high voltage diff probe using an INA217 instrumentation amp.I'm having an issue understanding it's supply voltage from it's datasheet:(Maximum)(Recommended)I can't figure out if they're meaning (+-)15V between it's supply rails or between each one and ground.I've tried checking TI's pdf on reading opamp specs but couldn't find an explanation on supply voltages. I also tried checking forum posts for similar questions but found nothing.does anyone know how to read suck supply voltages?Best regards,Matt.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 13, 2022, 02:06:45 pm
content: Each rail and ground.EDIT: Do a thought experiment. Assume you attach your voltmeter correctly and measure only between each rail. You see +30V. How would you know was as +15 and the other -15? They could be, for example, +25 and -5 or +30 and 0.

author: mattisafur
author_rank: Newbie
timestamp: March 13, 2022, 03:37:32 pm
content: Thank you!QuoteThat's a good point! I'll try thinking about scenarios like this one next time I won't understand some part of a datasheet.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 13, 2022, 04:16:57 pm
content: They are specifying minimum and absolute maximum for the supply rails eg 9 volts to 36 Volts total. Often referred to as supply span.So they are saying -4.5 0 +4.5 to -18 0 +18. Its not a good idea to run at the absolute max supply.Of course it doens't necessarily have to be centred around 0V, you could run from +5 and -9 if you like. Check your Vout vs Vcm plot to make sure the inst amp is inside its working range.

author: rstofer
author_rank: Super Contributor
timestamp: March 14, 2022, 12:43:49 am
content: A couple of things to be aware of: First, notice the limit on input voltages, 0.5V below the lower rail and 0.5V above the upper rail. Don't work outside these boundaries. Those are the MAX limits, there may be other restrictions that won't destroy the device but it might not give the proper output.Second, your datasheet screenshot doesn't show it but the datasheet should tell you how close to the rails the output can swing. In the good old days, a system with +- 15V rails might work over a range of +-10V for inputs and outputs.There will also be a limit on how close the inputs can swing toward the rails.See around 10:00 here:Here is a paper on 'phase reversal' where the output does weird stuff at various input levels:https://www.analog.com/media/en/training-seminars/tutorials/MT-036.pdfDave has some good op amp videos as does w2aew

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 14, 2022, 02:50:23 am
content: Hi,There is a typo on the INA217 datasheet:The difference between V+ and V- shouldalwaysbe positive. That is V+ more positive than V-.They show the difference as +/-, which is wrong.regards,Jay_Diddy_B