hybridfree/eevblog-posts huggingface dataset:
:: does element14 query always crash? (solved) - Page 1
Forum section: electronics / beginners

author: 3roomlab
author_rank: Frequent Contributor
timestamp: February 23, 2015, 11:51:36 am
content: as it always happens for me ... i wonder(solved : using separate browser (in my case : opera) slight java glitch. as it happens, the older opera 11.xx seem to be faster than firefox and chrome)

author: matseng
author_rank: Frequent Contributor
timestamp: February 23, 2015, 12:35:00 pm
content: Can't recall that I've ever seen that. I use the Malaysian version of E14, but my guess is that it shares exactly the same codebase as the Singapore version.A tip that might come in handy- I've setup "E" as a Search Engine shortcut in Chrome to search in element14. This is the URL I'm using:Code:http://my.element14.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=83&storeId=10188&gs=true&st=%sIt probably needs some more adjustments in addition to change the "my" to something else, but I suppose that it would be easy to figure out by looking at the URL after a normal direct search on the site.

author: David_AVD
author_rank: Super Contributor
timestamp: February 23, 2015, 09:20:47 pm
content: Do you have cookies enabled for E14 ?Some web sites will crash in spectacular ways when cookies are disabled.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: February 24, 2015, 05:41:41 am
content: i see, snooping cookie munsters ! thanks

author: adam1213
author_rank: Regular Contributor
timestamp: February 24, 2015, 11:29:01 am
content: this is an issue with element 14's website. Each time you visit a page element 145 adds the information on the page you have visited to a cookie. Eventually the cookie gets long enough that the request is too long. Solution: buy from another vendor / get element 14 to fix there site / clear the cookie manually. Note the key that gets long is likely bnTrail

author: 3roomlab
author_rank: Frequent Contributor
timestamp: February 24, 2015, 11:32:34 am
content: yea, im quite used to it crashing.it normally happens after about 10 steps into a detailed item search/filteringedit :: i think i will do an experiment, i will install opera browser, and use opera to browse e14 exclusively to see what happens.

author: adam1213
author_rank: Regular Contributor
timestamp: February 24, 2015, 11:50:38 am
content: Quote from: 3roomlab on February 24, 2015, 11:32:34 amIt will likely work for a while until the cookie gets too big again.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: February 24, 2015, 12:15:14 pm
content: the java is not happy lol
Does impedance affects chance of arc/corona discharge? - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: May 19, 2017, 12:54:53 pm
content: Imagine electrode that is connected to AC source that outputs sinewave at fixed voltage level.If the voltage gets high enough,arc or corona discharge will happen.I have read that maximum power transfer occurs when the impedance of source matches the impedance of load,I remember that voltage source doesnt like if its output impedance is higher than impedance of load becose the voltage at the load decreases as result.Impedance of free space is 120ohm,air is nearly same impedance as free space,for all practical purposes its same.My question is,does the output impedance of the AC source matters when it comes the value of threshold voltage at which arcing or corona happens?For example,our source with voltage X,is it possible,that at certain voltage level,arc will form if its output impedance is low,around 120ohm but dont form at the same voltage level that created arc previously at 120ohm if the output impedance is 10000 ohm? Does lowering the AC source output impedance from large values closer to 120 ohm decreases voltage threshold at which arc happens?

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 19, 2017, 02:48:24 pm
content: The impedance of free space is more like 377 ohms, not 120; the impedance of twisted pair as used in ethernet cable is close to 120 ohms.Maximum power transfer does, indeed, occur when the source and load impedance match, but this is not necessarily a desirable goal as it means that half the source voltage is dropped across its own internal resistance/impedance.The tendency for corona/arcing to occur at a given voltage depends mainly on the gap between the electrodes, of course, as well as the pressure of the gas (if any) and its tendency to emit secondary electrons. This is codified in an equation called "Paschen's Law" and it is surprisingly accurate for a wide range of gases, pressures and electrode distances (IIRC, it does break down - pardon the pun - at really tiny gaps). The graph produced is roughly in the shape of an inverted parabola with a minimum arcing voltage in the range of 1-10 Torr for most gases (where 760 Torr = 1 Atmosphere = 1 Bar (more or less)).Corona is, essentially, a low current (read: high impedance) "glow" discharge and as such won't be affected too much by the source impedance. Arcing, however, tends to be a much lower impedance type of discharge and so if the source impedance is too high then I would expect that arcing would stop almost immediately after it starts.
Does It Matter How I Connect LNG In This Power Splitter? - Page 1
Forum section: electronics / beginners

author: Boris_yo
author_rank: Frequent Contributor
timestamp: November 23, 2011, 03:52:38 pm
content: Does it matter how i connectNeutral,Live andGround cables in 2 socket power splitter? I want to connect wires to right socket which is conductor to left (or vice versa), but since Ground wire is perfect in length to connect to left socket, i don't want to mess with it and connect right away, however Neutral and Live cables connect to right socket because i just want to, so i was wondering if i can connect Neutral and Live in right socket with Ground being on left socket.Which of the following 3 variants is the perfect and which is safest or better both?

author: 8086
author_rank: Super Contributor
timestamp: November 23, 2011, 04:36:49 pm
content: Yes that is fine.

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: November 23, 2011, 06:24:51 pm
content: Electrically it makes no difference*. However, "Neatness counts" as they say. So I would recommend connecting all three wires to just one plug's terminals. That way you can clearly see the incoming lines go to one plug, then get extended to the other.(*As long as Live goes to Live, Neutral goes to Neutral, and Ground goes to Ground, obviously.)

author: IanB
author_rank: Super Contributor
timestamp: November 23, 2011, 06:39:12 pm
content: That picture does not look right. The white box looks like a wall mounted power outlet designed for fixed installation. As such the cable connected to it would normally be a solid core cable installed in a conduit or behind a wall. However, the cable you appear to be connecting looks like the end of a stranded flexible cable. This is the wrong kind of cable to be connecting to that box (the box does not have the right kind of screw terminals for flex and it does not have strain relief where the cable enters). Also the white box does not look like it is designed for use as a free-standing socket.I recognize that everyone in the world has been doing dangerous things with mains electricity for years, and thatmostpeople in the world have not electrocuted themselves or others by doing so, but you are scaring me. Please try not to kill yourself.

author: Boris_yo
author_rank: Frequent Contributor
timestamp: November 23, 2011, 11:39:42 pm
content: Quote from: IanB on November 23, 2011, 06:39:12 pmWhat is strain relief? This?I don't think it can be attached to wall. Here is bottom/behind look:

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: November 24, 2011, 06:53:30 am
content: Those undrilled holes in corners are actually for wall mounting
does my power converter have the correct voltages?  - Page 1
Forum section: electronics / beginners

author: blueagent004
author_rank: Contributor
timestamp: July 14, 2019, 03:19:23 am
content: my game console voltage: 100v, 47w, 50/60hzmy brand new power converter: AC 220v, 50w MAX, 50hzthe converter is for 100v game console to be used in local 220v socket here.i used to have an old one but i threw that one away and bought this new one.i bought the correct power converter right?

author: bdunham7
author_rank: Super Contributor
timestamp: July 14, 2019, 04:03:52 am
content: If you think the triac choppers are a POS, it can be worse. I've seen them simply use a rectifier.

author: blueagent004
author_rank: Contributor
timestamp: July 14, 2019, 10:55:09 am
content: i understand, thank you so much for helping me and sharing your expert knowledge!

author: Audioguru
author_rank: Super Contributor
timestamp: July 14, 2019, 02:39:56 pm
content: Why do they call it a "power" converter? it converts the voltage, not the power.The PlayStation is labelled NTSC which is the old American type of TV signals. It might not work with a modern American 4k TV nor European or Down Under TV.
does output current changes if capacitor is added - Page 1
Forum section: electronics / beginners

author: VickySalunkhe
author_rank: Regular Contributor
timestamp: September 25, 2017, 04:05:16 pm
content: does output current changes if capacitor is added in the circuitI used the multimeter with no load to check the current and got a reading of around 8amps from my power supplyBut after adding capacitor and connecting it to a load i was roughly getting 1amps

author: bjcuizon
author_rank: Frequent Contributor
timestamp: September 26, 2017, 05:57:33 pm
content: Quote from: VickySalunkhe on September 25, 2017, 04:05:16 pmDid you short the power supply with your multimeter set to amps? Maybe that's why you got 8 amps. But normally if you connect a cap on the output it should store more energy and discharge it later when needed.

author: innkeeper
author_rank: Unknown
timestamp: September 27, 2017, 12:39:12 am
content: i agree, something seems terribly wrong

author: Brumby
author_rank: Unknown
timestamp: September 27, 2017, 01:42:19 am
content: My initial reaction was that you have shorted the output of the supply with your meter on the Amps range, then added a load which only draws about an amp.Please check how you are using your meter!If you have done what Ithinkyou have done, making the same mistake on high energy circuits - such as mains - could cause your meter to explode.Using the current ranges on a meter requires more care and understanding than any other.

author: BrianHG
author_rank: Super Contributor
timestamp: September 27, 2017, 03:05:48 am
content: Show us your load circuit.For all we know, your load has a high frequency ripple in it which you meter may be responding to. The cap may filter out this ripple and be giving you the true reading.An example load would be a simple high current PWM led dimming circuit which doesn't have enough input filtering.
Does scope DC gain accuracy increase with Hi Res mode? - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: November 13, 2017, 06:16:52 am
content: I saw in datasheet of scopes from Keysight,Lecroy and R&S specification called DC accuracy,its usualy between 2% to 0.5%.8 bit scopes are around 2%,10bit 1% and 12bit 0.5%,I mean the real hardware resolution of the ADC.If I understand it correctly this spec tells how good is the scope at measuring voltage amplitude of signal,kind of like multimeter.This spec can be limited by either noise,non-linearity or resolution.My question is,can so called hi res mode,HD mode or eres increase the DC accuracy? I know that oversampling the ADC can decrease the noise,increase the resolution but does nothing to inherent non-linearity of ADC.Can these oversampling hi res modes help?I like the Lecroy hdo4000 becose it have 0.5% accuracy,I wonder if R&S RTO can match its DC accuracy,its only 8 bit 2% but it have 10 Gs/s ADC instead of 2.5 of lecroy so it can oversample 4x,will that increase the DC accuracy? What about Keysight S,can hi res mode increase the DC accuracy?
Does shorted highside VRM always killed the load? - Page 1
Forum section: electronics / beginners

author: Julian mustofa
author_rank: Newbie
timestamp: November 16, 2024, 01:23:43 am
content: Hi allNew beginners hereI just wondering if highside vrm shorted always kill the load even in split second?In my case i work on fixing shorted laptop GPU memory VRMI already replace all vrm toughand checked all resistance cameback normalBut still not sure if memory and memory controller inside the gpu core survived since 19V was going on this phase (even tough it just in split second)

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 16, 2024, 03:22:07 pm
content: I'm not sure what happened, but if you put 19V on the 3V3 rails there are a few options.1. You release the smoke from your low voltage chips.2. the 3V3 rails draws so much current that something in the power supply chain blows before the 3V3 side gets damaged3. Everything goes up in smoke together.

author: u666sa
author_rank: Frequent Contributor
timestamp: November 16, 2024, 04:00:00 pm
content: Quote from: Julian mustofa on November 16, 2024, 01:23:43 amYou have a chance hereA) VRM is dead, just one or two, but you replace all just in caseB) GPU is deadC) GPU and VRM is deadIt's all a guess. In case you guessed wrong, you don't get paid.So your real choice is either disable GPU and work on Intel, or let the laptop go as no repair.

author: magic
author_rank: Super Contributor
timestamp: November 16, 2024, 04:07:14 pm
content: AFAIK many of those controllers have overvoltage protection, which enables the low side and shunts high side's current to ground. Since the low side is usually beefier (due to higher duty cycle) and not all high side FETs necessarily fail together, this might save the load in some cases.But I have never repaired this kind of stuff so I don't know how often it works in practice.

author: Julian mustofa
author_rank: Newbie
timestamp: November 21, 2024, 01:53:53 am
content: Quote from: Doctorandus_P on November 16, 2024, 03:22:07 pmThe gpu memory vrm shorted into main 19VI found few memory was impacted by short and i replace itQuote from: u666sa on November 16, 2024, 04:00:00 pmafter working on it, 4 out if 8 gpu memory was faulty due to vrm short eventI replace it all. And fortunatelly memory controller inside core surviveQuote from: magic on November 16, 2024, 04:07:14 pmYep it has OVP and OCP circuit. But something i notice someone has deliberatelly removed 1 bat54cw diode and stick it to the board. I dont know the reason. I’am asumming the OVP and OCP circuit doesn’t work as should be when the short even happen. I’am gonna find out after gpu memory replacement was finally done
Does SiLabs CP2102 (USB <-> UART chip) support inverted TXD ? - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: October 30, 2013, 02:59:51 am
content: I know FTDI FT232R does, its just I can not find it in CP2102 datasheet, or maybe I'm too noob that I missed that while reading it's app notes ?Appreciate any experienced CP2102 users could give me a confirmation on this feature.I'm going to build a USB <-> IR adapter that will be used at my Fluke 287, it needs an inverted TXD, and currently at local CP2102 based adapter boards are plenty, while FT232R based are all gone OOS and have to wait for weeks.

author: Dave
author_rank: Super Contributor
timestamp: October 30, 2013, 03:10:06 am
content: Even if it doesn't support it, it takes just 1 transistor and 1 resistor to do it. Shouldn't be that much of a problem, right?

author: BravoV
author_rank: Super Contributor
timestamp: October 31, 2013, 01:25:41 am
content: thanks Dave.
Does ST MC Workbench implement Space Vector Pulse Width Modulation (SVPWM) ? - Page 1
Forum section: electronics / beginners

author: cadena
author_rank: Contributor
timestamp: April 07, 2020, 10:35:47 pm
content: Hi everyone,Could someone please help me know if ST MC Workbench implements SVPWM ? I have been looking at all features in the workbench but I haven't found any settings which allow tuning of the PWM algorithm. Thanks in advance.
does tempest server racks have a lifespan? - Page 1
Forum section: electronics / beginners

author: jorgeh
author_rank: Regular Contributor
timestamp: July 15, 2022, 07:39:31 am
content: HiI have a server rack that i acquire from the military and its a tempest. meaning it is RF shielded. I know like bulletproof equipment have a certain lifespan. does this type of filter have that aswell?Im asking to know if I can add that as a feature to the description of the article or it would be better to take those filters out and just sell the rack as is?.

author: Zenith
author_rank: Frequent Contributor
timestamp: July 15, 2022, 03:23:28 pm
content: This is pure guesswork, so see it in that light.If you are interested in Tempest, you do regular checks to make sure it still works. It probably rarely fails. You are not going to be looking for server cabinets on ebay, or in classified advertisements.If you are looking for used server cabinets on ebay, you are probably not interested in Tempest.What does this look like? Is it like a normal server cabinet, or is it like a bank safe?

author: Gyro
author_rank: Super Contributor
timestamp: July 15, 2022, 03:46:20 pm
content: It has things like conductive finger contacts around the door for emi screening. It's effectively a Faraday cage with filtering.

author: jc101
author_rank: Frequent Contributor
timestamp: July 15, 2022, 03:50:54 pm
content: Only really in that the standard change, or if a routine test shows up a problem.That doesn't look like a tempest (shielded RF) enclosure, this is the kind of thing that was Tempest rated from workplaces of old. But levels of shielding vary, depending on the environment and use etc.

author: jorgeh
author_rank: Regular Contributor
timestamp: July 15, 2022, 10:56:45 pm
content: Hi,no, I have a 40HE server rack that i got from army surpluss, I was just wondering if I can add that to the description of the article or its better to sell it as a regular rack?that is why i was comparing it to bulletproof material. I know after a certain time the material loose its effectivness. whith that meaning the if the EMI filters that are installed have a lifespan. although the label says backupserver, it had also some comms, the top has some antenna filters.i can make better pictures of the different filters, but I was just wondering if they have an utility life.it had some couple of old servers inside. dismmantling those servers were a piece of work, taped with copper band all inside.
Does the LM334 reference current source have a defined Rset range? - Page 1
Forum section: electronics / beginners

author: zdelarosa00
author_rank: Regular Contributor
timestamp: March 13, 2019, 09:37:24 am
content: Hello all!..I was looking in some videos for practical applications, and the TI datasheet, but there doesn't seem to have an specified resistor range.What it is defined is the operating voltage and the current limit of 10mA. So, if 40v is the max supply and 10mA the max set current, around 4kOhm?...That is actually my question. Because there is many many appication circuits and not all of them are exactly just references or plain current sources. So I was planning to make a component list and I want to know if I need a consideration for the set resistor value.Have a good day people, and thanks in advance.

author: newbrain
author_rank: Super Contributor
timestamp: March 13, 2019, 11:01:34 am
content: Rsetis independent of the supply voltage.Its value is given (in normal conditions) by Eq 3 on page 6 of thedatasheet.E.g. at 25° C == 298,15 K, for a current of 10mA, we have:10 mA = 227 uV/K * 298.15 K / RsetRset= 227E-6 * 298.15 / 10E-3Rset~= 6.8With Rset= 4000the current will be ~ 17 µA.Of course, one must be careful about power dissipation: with 40 V across the device and 10 mA through it, we have 400 mW.In a TO-92, at 180 K/W and 25° C ambient temperature, the "junction" will be at 180 * 0.4 + 25 = 97° C, exceeding the maximum operating temperature of an LM334 by 27 degrees (but what about Note 4?).

author: David Hess
author_rank: Super Contributor
timestamp: March 13, 2019, 02:26:32 pm
content: At the low end, 1 microamp requires a 68 kilohm set resistance.
Does the LM7912 have a built-in output protection diode? - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: February 19, 2021, 05:57:05 am
content: I heard that "the LM7912 has a built-in output protection diode" and so you don't need to add one between the input and output pins like you should do with the 78xx-series regulators.Is this true?The TI 78xx datasheet has a warning about "Shorting the regulator input" which is not present in the 79xx datasheet, but maybe the 79xx datasheet is an abridged version.Is this protection identifiable in the 79xx schematic?

author: bobbydazzler
author_rank: Regular Contributor
timestamp: February 19, 2021, 07:54:43 am
content: I can only see 2 diodes in the 7812 compared to 3 diodes for the 7912, claim looks to be true.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 19, 2021, 01:35:23 pm
content: You heard it on the grapevine or what? The man from TI says no. You need external diodes.Why would you risk it for 1 cent?https://e2e.ti.com/support/power-management/f/196/t/566228?LM7912-Ext-Diode-for-protection

author: magic
author_rank: Super Contributor
timestamp: February 19, 2021, 05:22:03 pm
content: There is a parasitic diode from the substrate (connected to -Vin) to every collector, including that of the output transistor.Whether this diode is sufficient to clamp reverse voltage to a value which is safe for the rest of the IC is another question, because substrate tends to be lightly doped and have highish resistance as a result.In absence of any concrete information in the datasheet, it's safer to include a diode.As for the man from TI, he quotes a sentence from the datasheet which doesn't seem exist in the datasheetThe other day I have seen a TI support drone mention thermal shutdown in LM723

author: ledtester
author_rank: Super Contributor
timestamp: February 19, 2021, 05:30:58 pm
content: Quote from: Terry Bites on February 19, 2021, 01:35:23 pmThanks for tracking this down - it reminds me to always read the fine print.The claim was stated in a video targeted at beginner synth builders. It was well done - except for this one claim made towards the end. His design only used a 1uF cap on the -12 rail, so he probably can get away without the diode - but not exactly for the stated reason.Quote from: magic on February 19, 2021, 05:22:03 pmIt's mentioned in the caption for Figure 2:https://www.ti.com/lit/ds/symlink/lm79.pdf

author: magic
author_rank: Super Contributor
timestamp: February 19, 2021, 05:38:28 pm
content: Right. So add the diode if you have more than 100µF on the output, simpleBTW, it's 10µF for the LM78 so that's still some improvement.
Does the NEO-M8T store configuration settings in internal flash? - Page 1
Forum section: electronics / beginners

author: Illusionist
author_rank: Regular Contributor
timestamp: May 19, 2019, 09:55:36 pm
content: I've read the datahseets and manuals until I'm crosseyed, and I still can't figure out decisively if I need an external memory on the NEO-M8T-0-00, or if it can save runtime settings/configuration to its internal flash. Or, if the flash is just for firmware updates.Most of the ready-made boards I see still have a memory chip, but not all.I only have one module to play with, and need to design the PCB for it, so I really need to know before I do.

author: wraper
author_rank: Unknown
timestamp: May 19, 2019, 10:02:15 pm
content: With flash it can do fast fix on satellites. Also it can do data logging.Quote

author: Illusionist
author_rank: Regular Contributor
timestamp: May 19, 2019, 10:20:24 pm
content: Quote from: wraper on May 19, 2019, 10:02:15 pmThat answers that then, thank you. I've also just found a note in the evaluation kit guide about saving the config to the SQI flash.
Does the ST version of the NE555 have a dead time on the outputs ? - Page 1
Forum section: electronics / beginners

author: Simon
author_rank: Unknown
timestamp: June 08, 2013, 02:08:39 pm
content: I need to drive a "push pull" type setup with an NE555 made by ST. but the datasheet say's nothing about any dead period between high and low to stop shoot through. Do i therefore assume there is none and that shoot through will occur unless i do something myself ?

author: edavid
author_rank: Super Contributor
timestamp: June 08, 2013, 03:09:38 pm
content: Are you talking about shoot through internal to the 555, causing supply current spikes, or shoot through in your external circuit?Anyway, all standard bipolar 555s are the same, and they have no dead time. CMOS 555s don't have dead time either, but they have less internal shoot through.

author: SeanB
author_rank: Super Contributor
timestamp: June 08, 2013, 03:51:35 pm
content: That is why there is the recommendation in the datasheet for the big 470uF or higher value capacitor connected to pins 1 and 8 right by the IC, as the output stages do have a lot of shoot through when switching. The CMOS versions suffer from this as well, but as the output devices are much faster the current spike is a lot smaller, and as well the larger threshold voltage on the devices and the quicker transition time of the output reduces it to a small value. The regular bipolar can have a 100mA plus pulse on the supply during switching, which often causes funny things if the supply impedance is high and the chip draws enough current to go into the indeterminate regions during the transition, often oscillating happily during switching or burning out.

author: edavid
author_rank: Super Contributor
timestamp: June 08, 2013, 04:00:51 pm
content: Quote from: SeanB on June 08, 2013, 03:51:35 pmWhat datasheet recommends 470uF? The TI datasheet shows 0.01uF.

author: SeanB
author_rank: Super Contributor
timestamp: June 08, 2013, 04:31:03 pm
content: Look athttp://www.doctronics.co.uk/pdf_files/555an.pdfpage 5 and you will see from 100n to 10uF recommended. Right next to the chip as well, and often the designers use 10 times bigger caps than needed.

author: Simon
author_rank: Unknown
timestamp: June 08, 2013, 08:47:07 pm
content: I was refering to dead times on the output to stop shoot through on my external drive transistors. I'll use a driver IC or other method
does the stall current of a dc motor change depending on polarity? - Page 1
Forum section: electronics / beginners

author: engineheat
author_rank: Frequent Contributor
timestamp: September 19, 2019, 02:58:27 pm
content: Hi,I'm connecting a AA battery to a small DC motor. I'd like to know from a theoretical standpoint if the stall current and the current when the motor spins can change depending on the orientation (polarity) the battery is connected to the motor. Also like to know if it can change in practice due to manufacturing variations.I'm doing some measurements with a meter but the reading are a bit unstable.thanks

author: Kleinstein
author_rank: Super Contributor
timestamp: September 19, 2019, 03:04:17 pm
content: The stall current should not depend on the direction, as the motor is not turning, so no directionfor not turning.The position of the brushes may not be symmetric. So some motors have a preferred direction. So the run current and speed can depend on the direction. However there are also motors that are symmetric for both direction - kind of a compromise for both.

author: Zero999
author_rank: Super Contributor
timestamp: September 19, 2019, 03:12:23 pm
content: To expand on the previous comment. When the motor is stalled, there's no back-EMF, so the only resistance present is due to the windings and brushes, which is independent of the supply voltage's polarity.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 19, 2019, 03:12:40 pm
content: To first order, no. There may be effects like stiction and commutator angle and such, but they should have only a small effect.Tim
Does the V3.1S have grounding issues ? Do you recommend fixing it ? - Page 1
Forum section: electronics / beginners

author: l3gi0n
author_rank: Regular Contributor
timestamp: September 20, 2021, 11:13:07 pm
content: Does theKSGER T12 V3.1Shave grounding issues ? Would anything happen if I don't fix it ?

author: james_s
author_rank: Super Contributor
timestamp: September 21, 2021, 12:04:53 am
content: What is a V3.1S? You really have to include more information if you want somebody to be able to give you a useful answer.
Does this air pressure difference module require some current control circuit? - Page 1
Forum section: electronics / beginners

author: Ineedtolearn
author_rank: Newbie
timestamp: April 27, 2022, 09:08:37 am
content: I have XGZP6897D air pressure difference module, runs on 5V. But I'm worried how to connect it to Arduino as the datasheet says: "Overload voltage(max.6.5Vdc) or current(max.5mA) may burn the ASIC and cause the sensor fail throughly." Do I need to control the current for it? If so, do I need to buy some IC for it or can I do it with analog components?Datasheet:https://www.cfsensor.com/static/upload/file/20220412/XGZP6897D%20Pressure%20Sensor%20Module%20V2.4.pdf

author: RoGeorge
author_rank: Super Contributor
timestamp: April 27, 2022, 09:15:54 am
content: Quote from: Ineedtolearn on April 27, 2022, 09:08:37 amThere's no need for extra protection measures, as long as you power and control the sensor with a 5V Arduino.
Does this Capacitor Look Like it's Ready to Blow Soon? Some sort of dust on top? - Page 1
Forum section: electronics / beginners

author: salil
author_rank: Regular Contributor
timestamp: August 06, 2014, 02:20:55 am
content: This is inside of aBESTK USB charging station. I purchased it on Amazon a while ago and I began to noticed that it was charging devices very slowly. It turns out some of the resistors for supply the data lines with the correct voltages had burned up.Anyway, I saw on Amazonthat some people were reporting some serious problems with this product overheating, so I thought I'd take a look to see if there's anything else that could be going wrong and I noticed one of the capacitors had what looks like some sort of beige dust on the top. I asked an electrical engineering friend (very non-practical type :p) but he says there's no way of tell if there's anything going wrong unless I desolder and measure every single one and have a full schematic of the entire product to reference (which I don't).Anyway,I've circled the capacitor in question, if anyone has any thoughts it'd be great to hear from you.Thanks.PS: There are two pictures of the same capacitor (and a neighboring one which does not seem to be physically deformed at all), my phone's flash is obnoxious so it may be a little hard to see everything in one photo or the other.

author: tautech
author_rank: Super Contributor
timestamp: August 06, 2014, 02:28:00 am
content: It looks VERY suspicious to me.Looks like leaking electrolyte.Best it be pulled and tested, then replaced.

author: retiredcaps
author_rank: Super Contributor
timestamp: August 06, 2014, 04:33:21 am
content: Quote from: tautech on August 06, 2014, 02:28:00 amI agree. It looks like dried up electrolyte.The vent suggests it might be United Chemicon capacitor. If it is a KZG series, they are known to be bad.
Does this chip look fried?? Beginner here! Thanks - Page 1
Forum section: electronics / beginners

author: Snakeboy
author_rank: Newbie
timestamp: June 09, 2017, 03:41:09 am
content: I opened up my LG 3D TV because it was turning itself off and on. I've read that chips like this can look burnt or discoloured if faulty..any advice appreciated!see attached pic. Thanks!

author: TimNJ
author_rank: Super Contributor
timestamp: June 09, 2017, 03:51:00 am
content: I would suspect a power supply fault, and not a chip like that.If it's turning itself on and off repeatedly, it might be in some sort of "hiccup" mode caused by a fault in the power supply. Usually, if something is shorted (or there is some sort of overload) in the switch-mode power supply, the PWM controller will effectively turn off the supply until the fault goes away and then restart again.First check if anything looks burnt, then check the output capacitors. See if they look visibly bad. If they look fine, they still might be bad. If you can, you should take them out of circuit and measure them with an LCR/ESR/multimeter. Might want to see if any power transistors look shot, or the diode on the secondary.

author: Chopsticks
author_rank: Regular Contributor
timestamp: June 09, 2017, 07:21:27 am
content: almost all tv's fails due to caps getting old/drying up. its a common thing and like he above post id check those first preferably with an ESR meter

author: CJay
author_rank: Super Contributor
timestamp: June 09, 2017, 08:50:41 am
content: Looks toast to me.Run your finger over the top and see if it's smooth.

author: ali6x944
author_rank: Frequent Contributor
timestamp: June 09, 2017, 06:05:32 pm
content: A good way to remove any confusion is to see the datasheet, input current section and try to measure the input current of the chip, if it is higher it is probably toast, I know it is hard in ur case and I don't expect u to do it, it is most useful in through hole packages because they are easier to test.

author: james_s
author_rank: Super Contributor
timestamp: June 09, 2017, 07:34:31 pm
content: It's very rare for parts like that to appear visually damaged. If it was blown up that badly the TV wouldn't work at all. Power supply issues are far more common, usually bad electrolytic capacitors and occasional collateral damage.
Does this look like a good device for charging supercaps? - Page 1
Forum section: electronics / beginners

author: JustMeHere
author_rank: Frequent Contributor
timestamp: September 03, 2019, 05:14:49 pm
content: https://www.digikey.com/product-detail/en/texas-instruments/LM66100DCKR/296-53541-1-ND/10273271Is this something you'd use to charge up a supercap when it's "on" then provide the normal reverse power protection a diode would provide when it's "off"?
Does this power selector circuit work? - Page 1
Forum section: electronics / beginners

author: Thane of Cawdor
author_rank: Regular Contributor
timestamp: July 12, 2020, 04:14:27 am
content: Hi,Just wanted to verify whether this circuit could work as a power selector (charge the battery and run the output from the input power line or run off battery power when the input power line is low) using an ideal diode.Would the enable pin need to be inverted on one of the sources to prevent reverse leakage current into the source/battery or will this setup work well enough?Thanks

author: Thane of Cawdor
author_rank: Regular Contributor
timestamp: July 13, 2020, 03:22:50 am
content: Update: the resistors in the diagram would be around 10-100K. The input power line should always be higher than the battery voltage - facilitating reverse bias condition on the inline battery ideal diode when powered up.

author: Peabody
author_rank: Super Contributor
timestamp: July 13, 2020, 04:01:37 am
content: I've never used those. It's not clear whether the load would automatically be powered by the highest voltage, which is what you need. Also, you can kinda do the same thing with a standard load sharing circuit - a P-channel mosfet, a Schottky diode, and a resistor.

author: Thane of Cawdor
author_rank: Regular Contributor
timestamp: July 13, 2020, 04:45:21 am
content: Thanks for that. I think the only concern with the load sharing circuit would be the much higher forward voltage drop across the diode at 500-1000mA. For the 'ideal diode' ICs these are quoted to be sub 100mV.Would inverting the enable pin input (with respect to the other) on one of the ideal diodes make it more like the load sharing circuit without the forward voltage drop perhaps?

author: kjr18
author_rank: Regular Contributor
timestamp: July 13, 2020, 09:41:42 am
content: Not really, Shottky diodes have smaller voltage drop than other, and it's not really important in this design, as voltage is boosted anyway to 5V. SB220 in this example has about 400mV @1A. Not so much i think.

author: Peabody
author_rank: Super Contributor
timestamp: July 13, 2020, 02:22:38 pm
content: In the load sharing circuit it's assumed the charging source is ultimately mains powered, so dissipating a little heat in the diode doesn't really matter. But the mosfet switches the battery with very little drop.If I read the datasheet correctly, you can have both ENables turned on all the time, and the highest voltage source will always power the output. I don't think you have to invert one of the enables because it says the diode has to be forward biased to conduct. So if V1 is higher than Vbat, then it would always power the output if it's plugged in, even if both diodes are enabled.It also says you need capacitors on input and output which you wouldn't need in the load sharing circuit. And there would be some current needed to power the diode logic when running on battery - a few microamps which you wouldn't have with the plain load sharing circuit.

author: Thane of Cawdor
author_rank: Regular Contributor
timestamp: July 19, 2020, 06:49:19 am
content: Thanks all for the responses
Does this schematic make sense? - Page 1
Forum section: electronics / beginners

author: Carbox312
author_rank: Newbie
timestamp: September 02, 2024, 10:53:36 am
content: Hi,I have a few power supplies/transformers with voltages around 17-20V, I decided to turn them into bench power supplies.The schematic is based on the diagram from this discussion:https://forum.contextualelectronics.com/t/alexs-linear-power-supply-build-log/1235I also added a preregulator from this topic:https://hackaday.io/project/4407-elbsupply-simple-linear-bench-supplyand removed the two operational amplifiers that doubled the ADC voltage. Instead of that, I plan to directly supply a 0-2.5V signal from the DAC.I'd also like to add an indicator for when the CC (constant current) mode is active. Would simply adding an NPN transistor controlled by the output of the U4 amplifier do the job? Additionally, while browsing for lab power supplies schematics online, I noticed that a few stability components might be missing (eg. antiparallel diodes at opamp inputs). Does this power supply have a reasonable chance of working properly?Thank you for all your answers!

author: MrAl
author_rank: Super Contributor
timestamp: September 03, 2024, 01:46:04 pm
content: Quote from: Carbox312 on September 02, 2024, 10:53:36 amHello,Taking a brief look it does look like it's got all the necessary parts for a linear supply with a switching power supply front end.It's got:1. Voltage feedback.2. Current feedback.3. Tracking regulator.4. Even has a constant current dummy load.You would have to test all those components to make sure they work as intended. That means making sure the individual sections work ok, and that also means making sure the transistors get the required gate drive when needed.I would assume you would do a simulation next anyway, and then also test the response speed. The response to an overcurrent would be an important thing to test. I mention this because I see U2 gate being driven with a 1k resistor, and Q3 gate being driven with a 10k resistor. Those two may need to be lowered quite a bit, but you could check that in a simulation before you bench test it. Bench testing is a must BTW as well as life testing under conditions of full load.You should also test to see that the tracking regulator keeps the output of the switcher at a reasonable voltage level for all outputs, and of course never goes too low.
Does this servo hack work by good fortune, or good design? - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: March 06, 2023, 05:47:19 am
content: To make a large servo motor they disconnected the motor inside a small servo then used the motor signal as the input to a high current motor driver and completed the feedback loop via a mechanical linkage from the large motor to the small servo arm.Presumably the circuitry inside the small servo was designed around the characteristics of the tiny motor originally used, however it seemed equally good at driving a much larger motor. Is that to be expected, or was it just good luck that it worked so well?
Does This Transistor AND Gate Work? - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: June 07, 2018, 08:23:51 pm
content: Hi,I've built a two-transistor AND gate. It's the first schematic in the link. When I set Voltage A to 0V and Voltage V to 5V, I get a Vout of 1.4V. This seems too high for what's supposed to be a zero value.These are the readings of my circuit. My Vcc is 6V.VA VB Vout0 0 05 0 00 5 1.45 5 4.2Is it missing a pulldown resistor?Thanks,Carlhttp://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/trangate.html

author: capt bullshot
author_rank: Super Contributor
timestamp: June 07, 2018, 08:49:01 pm
content: The output voltage is as one would expect. IMO still valid logic levels for a circuit running off a 6V supply,Because current flows through the 10k base resistor, the B-E junction into the 4k7 pull-down resistor. For better results, make the 10k resistors larger, e.g. 100k.

author: JS
author_rank: Frequent Contributor
timestamp: June 07, 2018, 08:54:56 pm
content: Usualy better to do a NAND and later a NOT, you have NOR gates in your link that whould do, just one transistor and don't even put the second resistor, unless you needed an OR gate following the AND.Propagation delay could be higher this way but you are probably not going to get high speeds with this circuit anyway.JS

author: Zero999
author_rank: Super Contributor
timestamp: June 07, 2018, 08:56:09 pm
content: That's because the base-emitter junction is conducting, passing current through.Yes, it's an emitter follower, so the output voltage is also always lower. than the input, which won't matter for a single stage, but it will be no good if more than two stages are cascaded. Some voltage gain is required. As mentioned above, a better AND gate can be built by connecting a NOT gate after a NAND gate. When the transistors are in common emitter configuration, there's plenty of voltage gain.

author: eev_carl
author_rank: Regular Contributor
timestamp: June 07, 2018, 08:59:53 pm
content: Thanks, the 100k resistors bring the Vout down to 200mV when only VB is on. With both on, Vout is 3.7V,

author: amyk
author_rank: Super Contributor
timestamp: June 08, 2018, 12:21:41 am
content: ...and now you know why RTL is almost nearly obsolete
Does this UVLO circuit work in the real world? - Page 1
Forum section: electronics / beginners

author: PeLa
author_rank: Contributor
timestamp: September 03, 2020, 08:51:37 am
content: Hi there,I've been struggling trying to figure out how to set up an UVLO for a 7 cell Lithium Ion Battery (max 30V, with a 21-22V cut-off).What "I" have come up with is pieced together from various different sources. I am a bit insecure about it. Something does not look right...The SPICE simulation looks ok to me (see below). It should turn off at around 21-22V.The N-channel MOSFET that I have chosen should be able to handle that the current (2-8A).Let me know, if this is complete horsesh** and doesn’t make sense at all.Cheers,Pete

author: PeLa
author_rank: Contributor
timestamp: September 03, 2020, 11:57:07 am
content: PS: Here's the design I tried to adapt.

author: Ian.M
author_rank: Super Contributor
timestamp: September 03, 2020, 12:24:49 pm
content: as there's no emoj for a reeking pile of s--t being circledby a dark cloud of flies.If you sim something in LTspice its generally a good idea to post the .asc file and if it uss non-standard parts, zip it it up with the 3rd party models and symbols required.See if you are quite so happy after adding:Code:.step temp 0 75 25to the sim!Also what about the approx 25W dissipation in M1 at max. load?

author: PeLa
author_rank: Contributor
timestamp: September 03, 2020, 12:33:55 pm
content: Thanks!Oops. Temperature... that's not gonna work. I don't think I need to attach the components after running the sim at different temperatures.Can you point me in a direction how to do undervoltage lockout of a 30V source in a less stupid way?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 03, 2020, 12:45:25 pm
content: The NMOS is a source follower, so it will always drop a few volts when "on".You need a low-side switch, or a PMOS and complementary enable (active low).Have you considered a battery management IC instead?Tim

author: PeLa
author_rank: Contributor
timestamp: September 03, 2020, 12:50:21 pm
content: Quote from: T3sl4co1l on September 03, 2020, 12:45:25 pmThanks. Battery Management IC. I believe that's the keywords I needed.Looking into them now. Also thank you for the explanation!
Does using differential ADC input at only pos. range halve adc bits ? - Page 1
Forum section: electronics / beginners

author: Spikee
author_rank: Frequent Contributor
timestamp: October 07, 2014, 02:48:48 pm
content: Hello,In a project of mine i'm using the MCP3428 - 4 channel 16bit delta-sigma adc to measure voltage. When using it in differential mode the range is -VREF to +VREF (vref is 2.048v).But i'm only using the 0-> +2.048V range in my circuitry (voltage is always positive). Is the usable amounts of adc bits now full scale / 2 ?So is my 18bit adc now a "usable" 8bit adc ?Datasheet:http://www.microchip.com/wwwproducts/Devices.aspx?product=MCP3428Circuit:(this is just a random opamp i chose)Edit:I think i found it , it is still 16bit full range. Only the sign bit changes.

author: German_EE
author_rank: Super Contributor
timestamp: October 07, 2014, 03:00:38 pm
content: You are close in your theory but there is a small error. If you have an 18-bit ADC with a +/- input and you only use the positive half then you have a 17-bit device. The device has a range from 00000 Hex to 2FFFF where zero is 1FFFF.

author: rob77
author_rank: Super Contributor
timestamp: October 07, 2014, 03:14:04 pm
content: just one note... half of 16bit is 15 bit not 8 bitso in fact you are halving the adc resolution, but to 15 bit not 8 bit.

author: Spikee
author_rank: Frequent Contributor
timestamp: October 07, 2014, 03:56:24 pm
content: Quote from: rob77 on October 07, 2014, 03:14:04 pm2^16 = 655362^15 = 32768you are rightQuote from: German_EE on October 07, 2014, 03:00:38 pmYou right, I missed that
Doing it the hard way:  Making a JK Flip Flop with transistors. - Page 1
Forum section: electronics / beginners

author: Pageygeeza
author_rank: Newbie
timestamp: January 11, 2014, 02:18:15 pm
content: I've been messing about with the idea of making a fully functioning JK Flip Flop from Transistors, (just because I can). I've got the logic sorted out and a rough transistor/resistor PCB layout. I'll leave the pics at the bottom.The thing is each logic gate consists of TTL, (so for a three input NAND there are three NPN transistors with 100k resistors for the inputs to the transistors and a 4.7k resistor from the positive side, with the output after the positive supply goes through the resistor.Both images have the same logical layout.Would this be good enough to construct the whole JK just from logic alone?