hybridfree/eevblog-posts huggingface dataset:
Difference between TL1431 vs TL431 Programmable Reference - Page 1
Forum section: electronics / beginners

author: belzrebuth
author_rank: Frequent Contributor
timestamp: August 22, 2021, 12:19:42 am
content: I was repairing a switching power supply and noticed that it has a TL1431 installed where I would typically see a TL431.That part was faulty so I tried replacing it with a TL431 because I thought the extra "1" would be a manufacturer's deviation and not another part because I've never came across a TL1431 before.The power supply didn't output the right voltages though so I quickly turned it off and googled the part.From a quick glance at the datasheets I see a lot of common typical applications (the PSU I have here uses it as a reference with two resistor that set the output voltage).They're also both stated as "zener diode replacements" so either there's still a fault in the power supply or I haven't had a proper look at their datasheets.edit: It was a bad cap, so now voltages are correct! My question remains though..

author: magic
author_rank: Super Contributor
timestamp: August 22, 2021, 08:54:26 am
content: Absolute maximum ratings and recommended conditions are the same, specs are barely different and mostly overlap each other when unit to unit variation is considered.The main difference is that 431 is 2.495V nominal and 1431 is exactly 2.5V at the cost of marginally worse typical thermal drift. Good enough for a PSU either way.You could compare typical characteristics too but I doubt that the differences will be larger than those between TL431 of different manufacturers.

author: wraper
author_rank: Unknown
timestamp: August 22, 2021, 09:51:40 am
content: Quote from: magic on August 22, 2021, 08:54:26 amTL1431 is more precise, 2.5V +/- 10mV. But TL431 (from TI) is 2.495V B: 0.5%, A: 1%, Blank: 2%

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 23, 2021, 06:15:28 pm
content: There are some 100+ different variants of the "TL431"It is a very popular chip, made by many different manufacturers, and though they all have the same part number, there are slight differences in parameters.So you should get the datasheet from the actual manufacturer of your part and study that.And when changing to another manufacturer, study and compare differences.
Difference between two SRAMs - Page 1
Forum section: electronics / beginners

author: modernjack3
author_rank: Contributor
timestamp: September 03, 2018, 09:06:51 am
content: Hey guys,I am not sure if this is the right board to ask this question but for one of my school projects I have to buy some SRAM chips and I stumbled upon 2 possible candidates.I am not new to electronics and normally dont have any trouble with reading datasheets, even for rather complex parts.My problem is that one of them is less expensive than the other one and I cant put my finger on why that would be.SRAM 1:https://www.mouser.at/ProductDetail/870-61WV5128B10TLISRAM 2:https://www.mouser.at/ProductDetail/ISSI/IS61WV5128EDBLL-10TLI?qs=DfG0HhEx1UX7T0hBwcg54A%3d%3dThe latter SRAM is less expensive, seems to have the exactly same packaging & specs and has ECC.But the first one is, according to mouser, "newly released" - so how come they would release a "worse" SRAM for a higher price??It would be really cool if you guys could let me know if I am missing something major here?Thanks in advance, Jack

author: newbrain
author_rank: Super Contributor
timestamp: September 03, 2018, 09:20:32 am
content: I don't trust very much the "new" moniker on Mouser:The ECC SRAM's datasheet is dated 2011, the "new" SRAM's is dated 2009...At a first look, they seem to have the same timings, the ECC one declared current consumption for 10ns grade is lower.

author: KrudyZ
author_rank: Frequent Contributor
timestamp: September 03, 2018, 07:23:49 pm
content: Most likely the ECC part is built on a smaller process node, allowing them to hit the same performance at lower power with a smaller die which makes it cheaper.
Difference between voltages in a simple dual tracking supply - Page 1
Forum section: electronics / beginners

author: OscilloscopeSeeker
author_rank: Newbie
timestamp: April 22, 2025, 01:29:42 pm
content: Hi! I have built a simple dual tracking supply using LM317 and LM337. But I get a 0.5 volt difference between the rails. For example: +5 volts and -5.5 volts, or when potentiometer is in the minimum position, I get +1 volts and -1.5 volts.I played around with digital staff before, but I'm very new to to analog, and currently out of ideas what can be wrong.Things I checked:1. Checked the polarity of soldered diodes and capacitors.Everthing looks fine.2. Checked traces on the PCB for high-impedance areas and continuity at all.Everthing looks fine.3. Checked datasheets for possible sources for inaccuracies.The formula for the output voltage has an additional part that depends on the current of the control pin. However, the datasheet also states that the maximum current Iadj is 100 µA, so the maximum voltage drop in my circuit is 10 mV (R = 100 Ohms), which far less then 500 mV.4. Checked output of the AC-DC power supply.Difference less then 50 mV.Parts that I used:TI LM337TTI LM317ATMEAN WELL RD-35135 kOhm, 100 Ohm 0.1 % resistorsPanasonic 10 uF electrolitic capsVishay 2.2 uF tantalum capsYangjie 1N4002 diodes10-turn 5 kOhm potentiometer wired as reostat

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 22, 2025, 02:30:07 pm
content: This circuit doesn't provide for both an adjustable output and matching output. The potentiometer is used to match the outputs. Somewhere near the middle of travel the two voltages will be equal.I haven't taken the time to see what the nominal value would be. Another means would be needed to change the output voltage.

author: Ian.M
author_rank: Super Contributor
timestamp: April 22, 2025, 03:21:57 pm
content: See the note on trimming R1 or R5 to improve tracking. The tolerance of the internal reference voltages of your regulators is poor enough that the circuit may be seriously out of balance if they are at opposite extremes. Worst case you need approx. +/- 10% trim range if you trim a single resistor. Trim for equal currents through a DMM on mA, shorting ADJ to ground, preferably simultaneously, or with the opposing ADJ grounded.

author: OscilloscopeSeeker
author_rank: Newbie
timestamp: April 23, 2025, 09:39:19 pm
content: Quote from: Ian.M on April 22, 2025, 03:21:57 pmOh, I thought this note mean that I need to keep values as close to each other as possible (that's why I chose 0.1% resistors).The difference dropped to ~130 mV when I replaced one of them with 99.38 Ohms. It's the largest resistance deviation I found in my stocks, and... wow, I didn't think I would ever be upset that 5% resistors would turn out to be too precise
Difference in commutation of brushless motor against pole numbers - Page 1
Forum section: electronics / beginners

author: sean87
author_rank: Regular Contributor
timestamp: October 31, 2017, 05:26:35 pm
content: Hi all,I have a BLDC motor with HALL sensors. Datasheet reads the motor is 4 pole. Somewhere else it says "Number of pole pairs 2"...I assume they both mean the same thing???It also has 3 HALL sensors at 120°I have some code samples that are for a 6 pole motor. My question is, what would be fundamentally different in commutation of a BLDC motor in respect to the number of poles.

author: Brumby
author_rank: Unknown
timestamp: October 31, 2017, 10:34:21 pm
content: Quote from: sean87 on October 31, 2017, 05:26:35 pmThe pole count is a simple counting exercise.Poles tend to work inpairsgroups. A group of 2 is common.So 4 = 2 x 2 looks right to me.
Difference in how these two VSWR bridges work? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 05, 2017, 01:38:57 pm
content: Both seem to do a similar job in providing metering of forward and reflected power, but one which I am using has a trim cap to tune for zero reflected power into a 50 Ohm dummy load, the other, which I have not tried, seems to do it with a variable resistor. What are the pros and cons of the two types and how does the "resistive" one work for zeroing reflected SWR into a known 50 Ohm load please? Is the "resistive" one just dependent on zeroing for reflected on the value of the fixed capacitors of C15 and C16? And the other allows some adjustment of the tuning via the trim cap?

author: dmills
author_rank: Super Contributor
timestamp: January 05, 2017, 06:57:33 pm
content: They are essentially the same circuit, just one has adjustable zero for reflected power and one does not.The operating principle is to sum and difference the voltage developed by the capacitive divider with half the voltage developed across the current transformers load resistor, it makes for a poor sort of power meter, but the ratio gives a rather non linear indication of SWR.73 Dan.
Difference in Resistor Types - Page 1
Forum section: electronics / beginners

author: Anson
author_rank: Regular Contributor
timestamp: June 28, 2013, 05:33:14 pm
content: Does anyone have a good online reference for the uses of different resistor types? Why they are used and how important it is. I have been having a hard time finding anything that explains it really clearly. I have found several videos or article that tell you about the different types and a few that have a few basic explanations but nothing in great detail. Or explaining how important it is. Reason for asking is because I want to learn and also because I have a resistor I want to replace that I cannot find an exact replacement for. It's a wirewound precision .4 watt and I need to know if I can replace it with a metal film. Since I cannot find its value in wirewound without going to a lesser wattage. Or getting a New Old Stock replacement off Ebay which I really don't want to do.

author: Paul Price
author_rank: Super Contributor
timestamp: June 28, 2013, 05:54:02 pm
content: Metal film at the proper wattage should do just fine or function better than the wirewound you are replacing. You don't mention anything about the resistors value and in what kinda circuit it is being used..don't you think adding this information to your post would make any answer easier?

author: Unknown
author_rank: Unknown
timestamp: June 28, 2013, 06:06:00 pm
content: The bookAnalog SEEKrets(available asfree PDF, the author accepts donations on his website) contains an excellent description of the advantages of the various resistor types.Wirewound resistors used to be common for precision applications back when metal film was not yet common. A metal film of the same or better accuracy should work fine in that application. Metal film resistors have a fairly limited peak current handling, wirewound and especially carbon composite are superior in this regard. You will need to look at the circuit to see if any of these aspects are important.

author: Anson
author_rank: Regular Contributor
timestamp: June 28, 2013, 11:19:26 pm
content: Quote from: Paul Price on June 28, 2013, 05:54:02 pmSorry I was going to add that bit of info but my wife interrupted me (apparently she was in a hurry). The original is a precision wirewound 0.5% .4watt 24.9k in a range switching application on a power supply. This one is reading out of spec and I was wanting to replace it. My 8840a is reading it as 31.9k.

author: Anson
author_rank: Regular Contributor
timestamp: June 28, 2013, 11:21:19 pm
content: Quote from: alm on June 28, 2013, 06:06:00 pmThanks for the reference I will give it a good read.
Difference in Solid state relays  - Page 1
Forum section: electronics / beginners

author: haramberries
author_rank: Newbie
timestamp: May 29, 2017, 05:05:15 am
content: Hello,I'm pretty new to this sort of stuff. to give some context, am planning to make a switch panel for my set up.I want it to turn on things like my monitors, computer, amp, lamp all through a switch pannel. With the monitors, I didn't want to take it apart, so I wanted to do it though the power cable. After doing some research, I found these Solid state relays. I wanted to make a small circuit so I could run a switch to the panel without the whole 240V, and instead, use 5v USB power or something. I wanted some help in choosing a cheap SSR for the job, there are so many of them ranging from a few bucks to $60+.Any help would be appreciated.,Thanks

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 29, 2017, 05:21:19 am
content: Some SSRs will use a TRIAC as their switch element. The thing about them is they continue to allow current to flow until it reaches near zero, when they switch off. This is no problem for AC where the current goes to zero 50 or 60 times a second, but doesn't work for DC. Those use MOSFETs or some other switching elements.Also, there are a complex matrix of overpriced industrial SSRs, expensive but very good industrial SSRs, inexpensive but good industrial SSRs, cheap but not good industrial SSRs and knockoff SSRs of each of these. If you're a mass manufacturer you don't use any of these but rather implement the SSR design yourself.Also worth knowing is that the common failure mode of an SSR is to always power on. Make sure that is OK with your use.I think practically anything will work with what you're planning to control so far, but provide a link to which SSR your thinking of using and for what exact purpose for specific advice.

author: Seekonk
author_rank: Super Contributor
timestamp: May 29, 2017, 11:02:03 am
content: Also note that it is common for the AC modules to leak many milliamps and devices like LED lamps will not fully turn off or AC may still be present in the circuit.
Differences between 1W and 2W LED chips? - Page 1
Forum section: electronics / beginners

author: bitwelder
author_rank: Super Contributor
timestamp: March 07, 2017, 06:59:28 am
content: The straight question is: is there any visible or measurable difference to recognize whether a LED chip is rated 1W or 2W?The story behind: I bought on eBay some 'USB 2W LED spotlight'.Inside the metal case there is only the LED chip and a 6.8 Ohm resistor. Measured at the USB powerbank, it takes about 0.26 A and the LED seems to run at 3.2V, and 3.2 V x 0.26 A = 0.83 WSo... is there a way to find out whether that LED in reality is a 1W or a 2W chip? (with a non-destructive test)

author: Ian.M
author_rank: Super Contributor
timestamp: March 07, 2017, 07:36:42 am
content: It would need a 3.6 Ohm resistor to get anywhere near 500mA, from 5.0V supply which would be 1.6W, (assuming negligible increase in Vf), rising to 1.8W at the max USB Vbus of 5.25V. As 3.6 Ohm resistors don't cost any more than 6.8 Ohm resistors, the way to bet is that is is entirely fake and either uses a 1W LED or rejects from a 2W LED line.It would be possible to characterise the LED's Vf change with temperature, by heating it in an environment chamber, pulsing the current with a very low duty cycle (e.g 1/1000) to minimise self-heating, which would let you estimate the die temperature from the measured Vf for a steady state current the same as the pulsed current, then you could estimate if doubling the dissipation would damage the junction, but the odds are that it isn't worth the effort.If you post a good macro photo of the LED (+ PCB) on a graph paper background, so we've got the scale, someone with more experience with current LEDs than myself may recognise the package and be able to guesstimate the power from the die area.
Differences between Dimmable and Non-Dimmable LED Lights - Page 1
Forum section: electronics / beginners

author: Stonent
author_rank: Super Contributor
timestamp: March 04, 2016, 04:21:46 pm
content: I found a fairly decent looking non-dimmable bulb at Walmart for $2.17 each (60W Replacement bulb) and it is quite bright (almost think it could replace a 75W bulb)However they had dimmable ones that looked exactly the same but were nearly twice as expensive.I was wondering what internal differences there were between dimmable and non-dimmable LED light bulbs?

author: Belgarion
author_rank: Unknown
timestamp: March 04, 2016, 04:56:54 pm
content: Digikey has an article describing dimming, which also mentions that LED lamps might not dim properly using a standard triac dimmer.http://www.digikey.com/en/articles/techzone/2011/jul/dimming-leds-with-traditional-triac-dimmersBasically the triac dimmer chops the AC sine curve and if the LED circuit is not made to handle that it will behave oddly.

author: coppice
author_rank: Super Contributor
timestamp: March 04, 2016, 05:01:40 pm
content: Try using a traditional dimmer with a LED lamp using a RC supply and wait for the flames to appear.A triac dimmer causes massive harmonic content, and at those frequencies the impedance of the capacitor in the RC supply can be rather low.

author: Seekonk
author_rank: Super Contributor
timestamp: March 04, 2016, 05:39:48 pm
content: Your results may vary. I have a A19 LED lamp I dim for my dog to get down stairs with only a .05uf capacitor in series. With another one, that makes the LED flash. I think most of them will dim somewhat with standard dimmer if a .47uf / 100 ohm RC network is parallel with LED lamp.
Differences between hot air rework stations - Page 1
Forum section: electronics / beginners

author: vgamesx2
author_rank: Regular Contributor
timestamp: December 29, 2017, 11:55:33 pm
content: Alright so does anyone know what the differences are between the cheap rework stations? I already did a quick search and didn't find much but maybe someone on here can tell me. (since it barely costs any more, I figure why not go ahead and get a 2in1 station)So there are a few models on ebay, are they just user interface changes or is one actually better made and which would you recommend?8786D -https://www.ebay.com/itm/8786D-2in1-110V-SMD-ESD-Electric-Rework-Desoldering-Soldering-Station-Hot-Air/372117763576?epid=544440252&hash=item56a3f275f8:g:u2kAAOSwHoFXv-ei8586 -https://www.ebay.com/itm/2in1-SMD-Rework-Soldering-Station-Solder-Iron-Welder-Hot-Air-Gun-ESD-3-Nozzles/182754818711?epid=1637662164&hash=item2a8d093a97:g:eAIAAOSwAYtWGLRc898D+ -https://www.ebay.com/itm/Latest-2in1-SMD-Soldering-Rework-Station-Hot-Air-Iron-898D-11Tips-ESD-PLCC-OY/142405066420?hash=item212800deb4:g:RC0AAOSwlndZNLaxThere are a few more but they start to get into the $50+ range, so I'd prefer to keep it under $45.

author: mavu
author_rank: Contributor
timestamp: January 02, 2018, 03:57:31 pm
content: I am looking at a hot air rework station too, and have done a lot of looking around.The general consensus seems to be that they all kind of work.But have no temperature stability, no safety features at all, and kind of work until they don't or burn your shop down.I decided to not buy one and save money for a decent one.If 45$ is your budget, my guess would be to buy the one with a color you like mostI'd love to be corrected if I'm wrong here, so if anyone has one of those cheap hot air stations and likes it, please tell

author: piguy101
author_rank: Regular Contributor
timestamp: January 02, 2018, 08:19:35 pm
content: I've got one of the 858D clones for cheap. It works good enough to reflow boards and remove components. Safety wise, it's not great. The ground connection on it is soldered instead of crimped or bolted and I can set the temperature so high (>500C) that the nozzle starts to deform, but I never need it at such a temperature anyway. I usually leave it around 300C.

author: GreyWoolfe
author_rank: Unknown
timestamp: January 03, 2018, 12:21:02 pm
content: If you buy a 2 in 1, when something fails, you can't really use it to fix itself. Then there is the quality. As piguy101 said, they kind of work. I have a Yihua 858D that is so-so. Santa brought me a Quick 957DW. More airflow, better ergonomics with the fan in the case instead of the handle. The Yihua is now a spare. I also have very good soldering irons because I saved until I could afford them instead of get it now. Figure out how much use the tool will get and save until you can get something that works instead of kind of works. Buying separates is the way to go unless space is really at a premium.
Differencial probe 10x 1MHz using as8066 - Page 1
Forum section: electronics / beginners

author: Apollo1234
author_rank: Contributor
timestamp: January 26, 2024, 04:29:32 pm
content: Hy there.Recently i got challenged to build a differencial probe with 10x attenuation, 1MHz BW using a low cost op amp. I alreay unerstood the attenuator but im still stuggling with the op amp feedback compensation, i read some articles but cant quite understand what im doing wrong, can someone pls help me and explain what is going on? the hase goes like crazy and cant understand where is the problem

author: MarkT
author_rank: Frequent Contributor
timestamp: January 27, 2024, 09:40:22 am
content: I'd be worried by low CMRR with that circuit - it relies on very accurately matched R's and C's for the attenuators and the differential stage. I'd suggest using a differential 10:1 attenuator circuit at the very least.I don't think any compensation should be needed for your circuit, but it will need proper decoupling, and the output can't drive capacitive loads direct above 20pF, so 100 ohms on the output is wise.BTW layout is critical for wide-bandwidth amplifiers, you haven't shown this.

author: RFDx
author_rank: Regular Contributor
timestamp: January 27, 2024, 10:31:05 am
content: The screenshot of your schematic is way to small (and compressed) to be readable.

author: Apollo1234
author_rank: Contributor
timestamp: January 27, 2024, 05:19:09 pm
content: I appreciate your understanding. I've recognized the issues with the CMRR, and I plan to address them by incorporating 0.1% resistors and a trimpot into the circuit. I had difficulty understanding the correct operation of the circuit initially, but now that I've gained clarity, I'll take into account real-world imperfections and work on resolving them.It may take some time, but I intend to design a carefully crafted PCB and conduct thorough testing. If the results are satisfactory, I'll return to share the design files, in case you or others are interested in replicating it.Thank you for your valuable time and assistance!

author: berke
author_rank: Frequent Contributor
timestamp: January 27, 2024, 06:29:07 pm
content: Phase in grads

author: RFDx
author_rank: Regular Contributor
timestamp: January 27, 2024, 09:41:37 pm
content: Quote from: berke on January 27, 2024, 06:29:07 pm"Grad". Capital "G" and no "s" at the end.

author: bdivi
author_rank: Regular Contributor
timestamp: February 13, 2024, 09:27:50 pm
content: Already built one several years ago. Works well up until 10MHz. A switch selects between x10 and x100.
Different behavior of a Rigol DS2000 and MSO5000 oscilloscope - Page 1
Forum section: electronics / beginners

author: diwou
author_rank: Newbie
timestamp: June 28, 2020, 01:56:18 pm
content: Hello,I am currently experimenting a little with ripple measurement. I have a DS2302A and a MSO5354 from Rigol.I connected two Rigol PVP2350 probes (Differential probe for poor people) to it (The same in each case), both set to 1:1. The two oscilloscopes I have also (at least I hope so) set the same. And then put both channels together with "A-B".The actual result looks basically the same, at least in the snapshot.On the Rigol DS2302A it looks like thisAnd on the rigol MSO5354 so:However, there are always short outliers of this type on the MSO5354, but these do not occur on the DS2302A.At first I thought of interference that was interfering with the MSO5354, but not the other oscilloscope. These "interferences" are not regular either. Sometimes it happens every few seconds, sometimes it happens every 10 seconds, etc.So I just recorded a few frames. And here's the weird thing. When I run the sequence completely (i.e. press the play button), this "interference" comes up too. But not always at the same frame. So when I play the sequence, sometimes you see a glitch on 18 frames, sometimes 2 or 3, and always on different frames.And all this during the same recording.If I go through the frames one by one, then I don't see this "disturbance" on the individual frames. But when I switch from one frame to the next, it happens from time to time that this "interference" is visible for a short time, but then it disappears immediately.I could only make this "disturbance" visible via the PC by pressing "Print Screen" so often, until I could catch this phenomenon.On the DS2302A, I can't create this phenomenon. Either the problem is now sitting in front of the table, or the MSO5354 has a small computational problem.Many greetingsDirk

author: PA0PBZ
author_rank: Super Contributor
timestamp: June 29, 2020, 11:57:57 am
content: How about a short explanation for future reference?
Different currents sharing the same conductor - Page 1
Forum section: electronics / beginners

author: SirRage
author_rank: Contributor
timestamp: September 06, 2021, 07:27:26 am
content: This is an electrical fundamentals question.I'm guessing the reason why a continuity tester works on a live conductor is that electricity tries to complete its own circuit. So it doesn't matter that the conductor is powered, the multi-meter will try to complete its own circuit. This is probably an oversimplification of it but I want to wrap my head and round this principle a little better.So does that mean you can have different types of power transmitted over the same conductor? Sort of like how you can have different radio frequencies over a common airwave?

author: magic
author_rank: Super Contributor
timestamp: September 06, 2021, 07:38:50 am
content: Theoretically, yes, current flows in loops and the same piece of wire may be part of multiple loops. Then the current through that wire is the sum of all currents.In practice, there are at least two issues to consider.Firstly, conductors have resistance. If it's a long cable with 1Ω resistance and you shove 1A through it, there will be 1V across the ends. Other circuits sharing the conductor may or may not like it.Secondly, safety. If a conductor is part of some mains circuitand it breaks, you may suddenly see full mains voltage across its ends. So if you are monkeying with a continuity tester on mains circuits, that's not the smartest idea.

author: Shock
author_rank: Super Contributor
timestamp: September 06, 2021, 08:59:10 am
content: Don't use a continuity tester (or diode/ohms mode) on a live circuit. Good meters can withstand mains voltages on these settings but it's a fail-safe and improper use.

author: Ian.M
author_rank: Super Contributor
timestamp: September 06, 2021, 09:05:10 am
content: Not only that, but any voltage drop caused by current in the live circuit can cause the continuity tester or ohmmeter to give a false reading, so its not only dangerous, but also worthless to use a continuity tester or ohmmeter on a live circuit.

author: tszaboo
author_rank: Super Contributor
timestamp: September 06, 2021, 11:50:09 am
content: The issue is, CT doesn't work as expected on live circuits. For example, if you have digital logic, all the "High" logic levels are technically connected together, and if you stick a DMM on it, it's current will just go: DMM -> Lead -> Logic IC -> power supply -> Other logic IC-> lead-> DMMSo you will get false readings.
Different ground - Page 1
Forum section: electronics / beginners

author: chrischina
author_rank: Contributor
timestamp: May 15, 2016, 03:23:10 am
content: I am currently designing a system where there are different kind of ground in it: "normal" power ground, analog grounf, ground for sim card.How do you advice to connect all those ground on pcb ?Should I create one split plane for each ground and then have a single point of contact to link all those grounds ?

author: danadak
author_rank: Super Contributor
timestamp: May 15, 2016, 09:38:57 am
content: "Normally" you split grounds to minimize load current effects on analogmeasurements, or to achieve noise margins for logic circuits. Take a lookat these PCB layout application notes, they should help.https://www.dropbox.com/s/ruaf9booe17jk8n/PCB%20Layout.zip?dl=0Regards, Dana.

author: Neilm
author_rank: Super Contributor
timestamp: May 15, 2016, 04:27:10 pm
content: Based on my experience - splitting the 0V is the wrong thing to do unless you have safety issues or youREALLYknow what you are doing.Remember, current flows in a loop. I have seen (and had to fix EMC problems on) too many boards where people have followed the "one 0V for analog, one for digital" route and got it wrong. In almost all the cases - having a single 0V plane in the PCB fixed the problems. The common issue I found was that people used one power rail for the signal into an op amp, and a different rail for the power supplies for that op amp thereby creating many loops of current around the board.I have also seen boards that work on measuring very low currents (<1pA) that did not have a split 0V.

author: Kalvin
author_rank: Super Contributor
timestamp: May 15, 2016, 04:37:36 pm
content: You may find the following document and the concept of the return current useful:http://www.hottconsultants.com/pdf_files/june2001pcd_mixedsignal.pdf
Different IC Package types - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: March 18, 2025, 01:53:15 pm
content: What factors determine the package type of an integrated circuit (IC)?I’ve noticed that different components come in various package types such as SOIC, DIP, DFN, and QFN. What are the key considerations that dictate which package is used for a given IC?

author: jpanhalt
author_rank: Super Contributor
timestamp: March 18, 2025, 02:11:04 pm
content: Market.

author: squadchannel
author_rank: Frequent Contributor
timestamp: March 18, 2025, 02:25:37 pm
content: Board space, mechanically space, hand soldering or reflow soldering, availability, price, ease of routing, whether the footprint fits the PCB fab's manufacturing capabilities, etc.

author: Freshman
author_rank: Regular Contributor
timestamp: March 19, 2025, 12:37:43 pm
content: My question was like, why do manufacturers, or how do manufacturers decide what a certain device package should be?Suppose, let's take LDOs or switching regulator products. A manufacturer makes a lot of them. Some of the Regulators are QFN, while some are DFN, while some are QFP?What factors are being considered by the manufacturer that enables to finalize that a particular package would be right?

author: AnalogTodd
author_rank: Regular Contributor
timestamp: March 19, 2025, 01:04:29 pm
content: Market is the major driver. However, there are a number of other factors that will weigh in on how a manufacturer packages a part.Die size: the die must be able to fit in the package with appropriate clearances.Number of pins and pad locations on die: part controls/interfacing need to come out to separate pins. There needs to be enough room on the die to place all these pins with clearances from one bond to another. Sometimes it is smaller to use four sides for pins instead of two.Thermal characteristics: depending on the type of part, a good thermal path is needed to dissipate power. For example, an LDO dissipates power equal to roughly (Vin - Vout) * Iload. That power creates heat that must be dissipated to avoid operational issues.Current handling: bond wires from die to package pins cannot carry too much current before becoming a fuse. Often multiple bond wires are needed to carry full current for a part, and only a certain number of bond wires can be attached to a pin.Product performance: there are a lot of parts out now where overall performance is improved with appropriate packaging. Some switching regulators use two switches that run their current loops in opposing directions to lower EMI.Solderability and inspection capability: some customers want to be able to do visual inspections of solder joints, others are OK with occasional X-ray. Leaded parts allow for visual inspection of solder joints, QFN and DFN do not.Overall, a big driver is getting things into smaller size overall. It is nice to have a cell phone with as much capability as it has in your pocket as opposed to the huge items that the same thing would have taken 25 years ago.
Different PHY layer - Page 1
Forum section: electronics / beginners

author: vignesh_shan
author_rank: Contributor
timestamp: November 19, 2020, 05:22:52 am
content: Hi ,While reading the MII in wikipedia. i had doubt on what is PHY ?They mentioned different types of PHY means ? what? Can you please explain me with some examples.Thanks,VigneshM

author: radiolistener
author_rank: Super Contributor
timestamp: November 19, 2020, 05:40:05 am
content: Quote from: vignesh_shan on November 19, 2020, 05:22:52 amPHY is a physical layer. PHY controller provide you with ability to send some symbol over physical medium, also it can do link negotiation with other PHY controllers and some stuff like physical cable measurement and automatic tuning for the signal power.When you're using PHY controller, you're needs to implement entire protocol stack, include flow control and other things. PHY controller don't know about MAC address or protocol things. You're needs to implement all these things.Different types of PHY in the quote means different type of medium, for example:- radio link- coax cable- twisted pair cable- optical cable

author: S. Petrukhin
author_rank: Super Contributor
timestamp: November 19, 2020, 11:49:13 pm
content: The RMII level is a linear bit stream is transmitted in binary. PHY encodes this bit stream into a physical signal for some transmission medium.This can be different media: twisted pair, optical fiber, optical air channel, radio channel, etc.RMII saves you from having to take care of the transmission environment, leaving it to a specialized CHIP. Moreover, you can change the transmission environment without modifying the program by simply installing another physical layer module in the slot.
Different power supplies for UART device and CP2102 USB-UART module - Page 1
Forum section: electronics / beginners

author: NightMoth
author_rank: Contributor
timestamp: June 24, 2025, 06:14:12 am
content: Hello allI have attached schematic to illustrate my questionPlease can anybody confirm, is it OK to use different power supplies forCP2102 USB-UART module (powered from laptop) and UART device (powered from whatsoewer)?As far as I can understand, if they both powered from the same laptop - they will have same ground level and all should be OK.But if they are powered from different power sources, they may have different grounds, and both devices can be damaged.Does CP2102 chip have a feature that allows use different power supplies?I can't figure it from CP2102 chip datasheet by myself...I can't see any optocouplers on CP2102 based module.My CP2102 is this onehttps://1ohm.in/product/cp2102-usb-to-ttl-usb-uart-serial-converter-module-2/My uart device is PIC16F73

author: pqass
author_rank: Super Contributor
timestamp: June 24, 2025, 07:11:33 am
content: For it to work, you must connect PIC "GNDREF" to the CP2102 module GND pin; leave the Vcc's unconnected.BUTthen if one is un-powered, this causes problems in the other.That is, TX on the powered CP2102 module will feed voltage into an unpowered PIC RX pin.Or, TX on the PIC feeds voltage into the un-powered CP2102 module.Ideally, you'd put a driver IC that can stand its inputs being driven if un-powered. Similar to how a MAX232 (RS232-TTL driver) can be abused but that would be overkill in this situation.Optocouplers will work but are slow or have to bedriven at high currents(10s of mA) to square-up the output transistor. Or need specialized high-speed digital outputs.You could use a two-stage NPN (with collector pullup to Vcc of the RX side); can't just use one as that inverts the signal. Or similar two-stage PNP but pulled to GND. This works because you can safely drive a base (or gate) without having a collector (or drain) to an un-powered pull-up. The only difference with using NPN or PNP is the default output when the gate is open (ideally RX should idle HIGH). Although, an un-powerd TX source might turn on a PNP/PFET anyway. See attached and simulationhere.

author: Peabody
author_rank: Super Contributor
timestamp: June 24, 2025, 04:35:16 pm
content: Quote from: pqass on June 24, 2025, 07:11:33 amCould you have a single-stage non-inverting circuit by connecting TX to the emitter of the NPN, its base through a pullup to the TX Vcc, and RX to the collector, with a pullup to the RX Vcc? I don't think you have any gain that way, but it might still be fast enough. I haven't really thought it through, but I don't think there's a problem if either side is unpowered.
Different sata connector - Page 1
Forum section: electronics / beginners

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 19, 2013, 07:42:19 am
content: Hello, i am having trouble finding this connector whoch looks like a sata+ power connector but smaller?The connector below is the normal sata + power but the one above the the one in question. I hve had a look on google but i think im searching the wrong search terms :/ does anybody know the connector type?

author: M. András
author_rank: Super Contributor
timestamp: August 19, 2013, 08:13:14 am
content: mini sata or micro sata i dont know its name either but these terms will find it for you its for the 1.8" drives and ssd-s

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 19, 2013, 04:52:46 pm
content: thank you very much

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 24, 2013, 09:39:38 am
content: ive have been looking into it further and have found out that it is actualy a 'slimline sata' connector.im looking to print a caddy to fit in my disk drive space to be able to hot swap my portable disk drives into there but i need a custom adaptor to change it from the slimline to the normal adaptor.

author: metalphreak
author_rank: Frequent Contributor
timestamp: August 24, 2013, 06:46:42 pm
content: That slimline connector is used on all laptop dvdrom drives - I assume that is where you are installing it?Plenty of dvdrom to HDD adapters out there to fit a hard drive in place of the optical drive.

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 24, 2013, 07:58:29 pm
content: Its a portable hdd in its own case, so i need to make a custom adaptor so the connectors are in the correct place

author: IanB
author_rank: Super Contributor
timestamp: August 24, 2013, 08:10:14 pm
content: Watch out for signal integrity. Unless you use an e-Sata connection, a sata cable is not necessarily going to be reliable for longer runs outside a case without shielding.

author: Alana
author_rank: Frequent Contributor
timestamp: August 24, 2013, 10:19:08 pm
content: Have my SATA cables 1m from motherboard connections to top of my workbench and the only unreliability i noticed is mechanical deterioration of plugs on those cables.
Different sized resistors for same wattage? - Page 1
Forum section: electronics / beginners

author: HUTCOMINT
author_rank: Newbie
timestamp: January 20, 2016, 02:04:24 am
content: I just received a bunch of different valued resistors from different companies for a project. Looking at the resistors I see they are all different sizes, even though almost all of them are 1/2 watt. A lot of the 1/2 watts are what I formerly assumed were 1/8 watt size (at least at radioshack they used to be). I doubled checked the datasheets and they are the right size. Does the physical size for the wattage change with the ohm value or am I missing something here?

author: Brumby
author_rank: Unknown
timestamp: January 20, 2016, 04:20:15 am
content: Quote from: HUTCOMINT on January 20, 2016, 02:04:24 amNo.The wattage rating is an indication of the ability of the component to dissipate a certain amount of power and not get damaged.The power will be turned into heat, which then will spread through the component body (and down the leads) until it reaches the surface. The temperature that you get at the surface will be a function of the heat generated and the surface area available. A larger component will have a larger surface area, so the temperature will be lower than for a smaller component.So, if you build a component that can withstand higher temperatures, you can make them physically smaller and still handle the power.But they will get hotter.

author: IconicPCB
author_rank: Super Contributor
timestamp: January 20, 2016, 08:10:59 am
content: What Brumby said:"...So, if you build a component that can withstand higher temperatures, you can make them physically smaller and still handle the power..."Just be aware that some companies will specify component temperature at which [articular power is being dissipated and ensure the temperature does not exceed YOUR safe limits . For example will the PCB get discoloured?Will plastic bitsa fail at the localised elevated temperatures?
Different super capacitor question - Page 1
Forum section: electronics / beginners

author: luddite
author_rank: Newbie
timestamp: March 14, 2021, 12:11:05 am
content: Hi,I am posting fresh as I have found something else with this unit so want to ask a separate question as I think it is faulty. (Green-Cap 2.7v - 500f)I checked it tonight and it was now showing 1.0v so put it on my rockseed 305p to charge to 2.7vIt took a while and then starting counting up from zero, which surprised me because meter said 1.0v before charging, however when I tried again whilst it was charging it showed hardly anything, I also tried a on a uni-t ut61e and it was the same, each time I checked it would show for example .8v on power supply but .2v on meter, I continued to check and each time it was way down on actual volts on my Fluke than it was on the power supply.I stopped it at 2.6v and it showed 1.9v and was quite hot, it also won't stand up properly now as the bottom has bellied out, just like a bike battery does when a regulator fails.Is think I have a dodgy one, comments are most welcomeThank you

author: bsodmike
author_rank: Regular Contributor
timestamp: March 14, 2021, 05:47:14 am
content: Quote from: luddite on March 14, 2021, 12:11:05 amHi, that doesn't sound good, especially if it looks bloated; sounds like it has let out the magic smoke. Usually they go 'boom'.I'd suggest disposing of this and replacing it ASAP.Thanks!
different type of bench psu - Page 1
Forum section: electronics / beginners

author: Kirigozo
author_rank: Contributor
timestamp: January 06, 2014, 05:31:47 am
content: Hi folks,The usual approach to psu config is a current limited voltage source with all control on the high side. Why not invert the lot and have a voltage limited current source with control on the low side?I'm interested in making a self contained (internal battery) unit with voltage between 0 and 12 and current from 1mA and 1A. I've modeled parts of the circuit below and, for me, it has interesting possibilities. I have not bread boarded any of it and probably won't be able to for a month or two (life can be an obstruction).

author: WarSim
author_rank: Frequent Contributor
timestamp: January 06, 2014, 05:40:42 am
content: Took a very fast peek.Did you notice the LED will need to pass over 1A of current when used to supply 1A to the output?It would be an incredible waist of power and an expensive LED.I recommend a different method of controlling you power LED.Sent from my iPad usingTapatalk

author: Unknown
author_rank: Unknown
timestamp: January 06, 2014, 05:46:08 am
content: Quote from: WarSim on January 06, 2014, 05:40:42 amWhat LED?

author: WarSim
author_rank: Frequent Contributor
timestamp: January 06, 2014, 06:10:05 am
content: Quote from: Lurch on January 06, 2014, 05:46:08 amHmm my real quick look was too quick.Sorry, my bad.Sent from my iPad usingTapatalk
Different types of capacitors and when to use them? - Page 1
Forum section: electronics / beginners

author: Dan123456
author_rank: Regular Contributor
timestamp: November 19, 2023, 04:18:06 am
content: I was just pulling apart some old pc power supplies to steal the components (inductors, the big chonky capacitors, etc).It got me to thinking, how do I know which kind of capacitor I should be using and when (and why)?Obviously, I need to take into account the capacitance, voltage rating, etc. but say a data sheet says I need a 1uf cap, how do I know if I should use an electrolytic, a ceramic, a MKT or a “green cap”? And what happens if I use the wrong one?Same thing with electrolytic. How do I know when I should be using a low ESR vs a normal one?I know this probably isn’t something that can be explained to me in a single postI am more wondering if you guys know any good resources for me like an “all you need to know about capacitors” book or website or YouTube video series that I can go away and learn all this from?Or is this more of just an experience thing that you eventually just kinda come to know?Google is not being particularly helpful in providing me with answersA lot of sites seem to either mostly tell me what I already know (I.e. to select a cap you need to know the capacitance, select 1.4 times the voltage you need and these are the different types etc. - but not really when to use each one, or more importantly, why), or are so technical that I don’t understand a word of what they are sayingThanks in advance

author: Konkedout
author_rank: Frequent Contributor
timestamp: November 19, 2023, 04:22:56 am
content: This might help. Pretty basic:https://www.we-online.com/en/components/products/ABC_OF_CAPACITORS_EN

author: MarkT
author_rank: Frequent Contributor
timestamp: November 19, 2023, 10:28:27 pm
content: https://www.rfcafe.com/references/electrical/capacitor-dielectrics.htm