hybridfree/eevblog-posts huggingface dataset:
Question on Buck Converters - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: June 03, 2020, 08:22:42 pm
content: I've been trying to design a power supply with an ultra wide input range (90-690VAC) and low output power (48V, <10W). As isolation is not required in the application, I was trying to come up with a buck converter. However, I've found out that buck converters are not practical for wide input ranges due to duty cycle limitations, and that flyback is a better alternative for wide input ranges. Has anyone faced this kind of dilemma?For example, considerthis application note from ST.They are designing a buck with 600VAC max input voltage. I'm trying to see if I could adapt this design for 690VAC input maybe adding an external FET in series to increase voltage rating. But again, I've been told from several manufacturers that a buck would not be a good choice for this wide range because the limitations chips have in terms on duty cycle.

author: ogden
author_rank: Super Contributor
timestamp: June 03, 2020, 09:41:42 pm
content: Quote from: Red_Micro on June 03, 2020, 08:22:42 pmWhat's the reason for you to think that several manufacturers are wrong and only way to find right answers is public forum where anybody can tell you virtually anything?

author: langwadt
author_rank: Super Contributor
timestamp: June 03, 2020, 10:12:07 pm
content: use a tapped inductor to increase the duty cycle?

author: ogden
author_rank: Super Contributor
timestamp: June 04, 2020, 02:39:08 pm
content: Converter IC used in said appnote has burst mode operation that solves "buck problem". Look at 230VAC input "no load" waveform, check burst frequency. If you are fine with resulting ripple and audible artefacts of burst mode, then your search is basically over.

author: David Hess
author_rank: Super Contributor
timestamp: June 04, 2020, 08:51:51 pm
content: Duty cycle limitations apply to all switching regulators operating in continuous conduction mode. Discontinuous conduction mode gives more flexibility but has other drawbacks.4:1 is typical for wide input range converters but 8:1 is feasible with the typical compromises in efficiency because the power semiconductors have to tolerate both high current and high voltage.
Question on current sensor sampling - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: October 12, 2018, 02:15:47 am
content: I'm using this current sensorTLI4970-D050T4located at the emitter leg of a power IGBT. This transistor is being switched at 10 kHz. How do I choose the convenient sampling frequency for the sensor? My bandwidth is 18 kHz. The IGBT is used in low side switching application to control a DC motor. How fast should I sample the current to get valuable information?
Question on custom boot loader implementation - Page 1
Forum section: electronics / projects

author: WillHuang
author_rank: Contributor
timestamp: October 25, 2017, 02:52:24 am
content: Hi all,At the moment, I'm reinventing the wheel and learning how to write a custom boot-loader. The development board that I'm using is the nucleo-f411re. With the boot-loader, I'll also build custom flash utility that will be used to flash the application image to the target board. I hope to use the raw binary file generated from Keil's fromelf.exe executable as the image to download instead of the intel .hex format files.My question is: Am I correct by saying that I am able to write directly to the flash sector(s) using the binary file without any sort of decoding? For example, if my main application starts at address 0x08008000, then every binary-based image data that I received should be directly copied to the start of 0x08008000?Thanks for the responses!

author: krho
author_rank: Regular Contributor
timestamp: October 25, 2017, 04:36:05 pm
content: Yes, the final bin file has all offsets calculated to the one you defined in your linker script, so you just start writing starting at that address.
Question on DC motor current measurement - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: October 31, 2018, 12:53:53 am
content: I have a previous thread about this, but I dropped the topic for a while. I'm using this current sensorTLI4970-D050T4located at the emitter leg of a power IGBT, which is being switched at 5 kHz.It's a low side switching configuration, i.e, motor at the collector leg. The sensor has the default parameters according to the datasheet. I'm thinking of triggering an external GPIO interrupt every rising edge of the PWM signal, and sample the current at this point. Do you think it's a good idea?

author: MasterT
author_rank: Frequent Contributor
timestamp: October 31, 2018, 01:31:49 am
content: Probably not a good idea. Fastest response time is 57 usec, period of the 5 kHz PWM is 200 usec, though at the best sensor could capture 30% PWM and up. What is more problematic, current is not a linear function, and slow sigma-delta adc is no-go with exponentially rising current. So, I'd say - no.

author: XaviPacheco
author_rank: Regular Contributor
timestamp: October 31, 2018, 01:50:43 am
content: The thing is that I'm trying to sample the current only when the transistor is ON. Do you suggest a better way?

author: MasterT
author_rank: Frequent Contributor
timestamp: October 31, 2018, 02:01:29 am
content: Better is SAR adc. Sensor is shunt or hall, someting like acs712. What is uCPU, does it have an adc?

author: XaviPacheco
author_rank: Regular Contributor
timestamp: October 31, 2018, 02:05:03 am
content: Quote from: MasterT on October 31, 2018, 02:01:29 amI can't change the sensor for now.

author: MasterT
author_rank: Frequent Contributor
timestamp: October 31, 2018, 02:25:52 am
content: Quote from: XaviPacheco on October 31, 2018, 12:53:53 amTriggering is correct approach with SAR adc, to ensure time stamping of the measurements relatively to PWM pulse. Here is different things, sensor has internal adc (slow sigma-delta) and filter, so it does sampling all the time, there is no trigger. Request over SPI is getting already processed data, and measurements is gonna to be erroneous with PWM.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 31, 2018, 05:37:25 am
content: There really should be an internal triggering path in your STM32 ADC & timer peripherals, but if not, using external GPIO interrupt of course works as well, as you describe.

author: XaviPacheco
author_rank: Regular Contributor
timestamp: October 31, 2018, 02:16:09 pm
content: Quote from: Siwastaja on October 31, 2018, 05:37:25 amTo read the sensor, I should pull CS low, read SPI data, and pull CS up. So, I'm receiving a digital signal, not an analog signal. That's why I'm not using any ADC in the uC. I came up with also connecting the PWM to a GPIO and trigger an interrupt to read SPI when rising edge of the PWM signal to avoid reading when the transistor is OFF. I was not sure of this approach. I'm simply going to test it.
Question on Linear Technology AN12. - Page 1
Forum section: electronics / projects

author: hamster_nz
author_rank: Super Contributor
timestamp: October 27, 2018, 10:41:36 am
content: I'm looking at the TXCO design inhttps://www.analog.com/media/en/technical-documentation/application-notes/an12fa.pdf,and see something I don't understand.In figure 6, is the 100k resistor on the Collector of the transistor supposed to be there? (see attached image)What does it do? On a breadboard it actually works of the collector is connected to 5V, but not with the 100k....

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: October 27, 2018, 03:46:42 pm
content: That almost has to be a typo. Probably wanted 100 ohms or so.

author: floobydust
author_rank: Super Contributor
timestamp: October 27, 2018, 05:29:06 pm
content: Strange, it's 100R in the Oct. 1985 version with 30k/100k for the data slicer.edit: From rare goldmine, 1990 Linear Applications Handbook, in a time before pdf's and the Internet became a thing, it is 100R with 100k/100k but 0.01uF for the data slicer.Something is changing part values around, I've seen three different versions.

author: glarsson
author_rank: Frequent Contributor
timestamp: October 27, 2018, 06:46:36 pm
content: Why is the AN calling it a TXCO? Also a typo or a different reality?

author: hamster_nz
author_rank: Super Contributor
timestamp: October 27, 2018, 06:57:07 pm
content: Quote from: glarsson on October 27, 2018, 06:46:36 pmIn the to left of the schematic there is a thermistor that generates a 0-4V signal that is used to nudge the XTALs frequency.

author: hamster_nz
author_rank: Super Contributor
timestamp: October 27, 2018, 06:59:14 pm
content: Quote from: floobydust on October 27, 2018, 05:29:06 pmHummm... 100 ohm makes sense...Thanks for checking this!

author: glarsson
author_rank: Frequent Contributor
timestamp: October 27, 2018, 07:04:26 pm
content: Quote from: hamster_nz on October 27, 2018, 06:57:07 pmYes, but that makes the design a TCXO, not a TXCO. Whatever that is.

author: hamster_nz
author_rank: Super Contributor
timestamp: October 27, 2018, 09:13:41 pm
content: Quote from: glarsson on October 27, 2018, 07:04:26 pmOh dear! I didn't see that...Maybe they let an intern update the appnote?
Question on Resistor Voltage dropper values for VCC supply of LED driver IC - Page 1
Forum section: electronics / projects

author: aaj
author_rank: Newbie
timestamp: March 14, 2022, 11:00:07 am
content: Hi,So I was designing the PCB for a 10W LED driver with the AL1676 controller(datasheet attached). From the datasheet, the application circuit shows that the driver takes its VCC supply through R1 and R2. The max value for VCC is 18V out of the approx 381V mains after rectification. Can someone help me figure out the formulas/calculations for these resistor droppers and for the value of capacitor C3.The Evaluation module(attached) shows the values of the droppers as R2=R3=180k. The IC uses Startup Current: 100µA, Operation Current: 170µA (5KHs Switching) which means with 180K*2 and 170µA, they should be dropping only 61.2V out of the 381V supplied to it. So 319V is available at the VCC pin when it can handle only 18V. How does that work!!

author: Ian.M
author_rank: Super Contributor
timestamp: March 16, 2022, 08:53:41 am
content: Did you see the Zener symbol in the block diagram to the right of 'Vcc management', labelled 'Vcc Clamp'? Later on it says the typ. clamping voltage is 15.5V.However the datasheet appears rather deficient as it doesn't specify a max. clamping current so all you can do is blindly use the dropper values from the eval board.
Question on using to similar Switchmodes output wired in series...  - Page 1
Forum section: electronics / projects

author: peteb2
author_rank: Regular Contributor
timestamp: May 01, 2020, 11:27:05 pm
content: I know doing it’s not a best practice & some makers state in their datasheet the procedure to use series connections, or don’t as the situation goes... In the climate of having spare time to hand I’m finishing off projects while using up pieces & parts to hand.I have a main circuit that needs a diet of ordinary regulated 12Vdc but we also have to run a couple of fans that sadly are both 24V. I have two identical 12V XP ECS100US12 SMPS units both capable of 8.3A, way beyond what will ever be needed current wise.The fans are switched by the circuit using a good ole TP122 Darlington. The XP datasheet makes no reference to series connecting their ECS devices.The fans are gutless for airflow on 12V so just wondering if I am up for a dummy award if I series the XP modules for the fan 24V only but take the o/p from one XP module for supply the main circuit? Of course I need to watch out on 0V connects & references to GND for electrical safety...XP data sheet:https://www.xppower.com/portals/0/pdfs/SF_ECS65-130.pdf

author: peteb2
author_rank: Regular Contributor
timestamp: May 02, 2020, 11:21:54 am
content: Scratch that previous meandering description. All sorted... i've used one 12V psu to supply the circuit and the 2nd unit now has a simple dc boost converter to make 24V at around 300mA for the two fans.All good...
Question regarding Laptop charging using cordless electricity - Page 1
Forum section: electronics / projects

author: arto
author_rank: Newbie
timestamp: February 04, 2015, 09:57:22 am
content: Hello!Sorry if this is the wrong folder - my first post up here.I have a laptop which eats 19V 4,74A (90W max). Let's say I have a wireless power transfer system which can deliver up to 100W (19V 5,26A). When I try to power up the laptop from bench power supply, the current fluctuates constantly from about 1,5 to 3,5A depending on the laptop CPU load. The problem is that my power transfer system resets/stops working every time there is this rapid current change (due to safety mechanisms), though it works perfectly in CC mode or when the laptop is being charged when turned off (with current at around 1.5A). Same issues with 70W rated laptop.I was wondering if there is any way to stabilize the current between my system and the laptop - since it could easy charge with 4.74A as long as it is constant current.Thank you!

author: amyk
author_rank: Super Contributor
timestamp: February 04, 2015, 04:00:26 pm
content: A big capacitor.

author: arto
author_rank: Newbie
timestamp: February 06, 2015, 07:22:11 am
content: Thanks!But will it actually drop even more power or how big should it be?Or is there any other solution?

author: Kjelt
author_rank: Super Contributor
timestamp: February 06, 2015, 08:39:08 am
content: Obviously your labsupply is not the right tool for this load.Why not spent $25 on a compatible laptop PS? Or if your laptop does not have the difficult three pin dc jacks (communicating with the PS about the power like Dell and HP) you can buy any second hand laptop PS , going for $10 on ebay

author: arto
author_rank: Newbie
timestamp: February 06, 2015, 09:04:58 am
content: Thanks!The problem is not with the lab supply - it works fine, I just use it to see the load current behavior. The problem is that my wireless power transfer system can supply enough power for laptop but only when the current is stable. In this case, as I mentioned, the laptop draws 1,5 to 3,5A which fluctuates according to CPU load.

author: tszaboo
author_rank: Super Contributor
timestamp: February 06, 2015, 10:32:55 am
content: Quote from: arto on February 06, 2015, 09:04:58 amHow much is the coupling between the wireless chargers?I saw mobile chargers having "glorious" up to 0.5-0.7 coupling...

author: arto
author_rank: Newbie
timestamp: February 08, 2015, 02:27:36 pm
content: Any other ideas? Anyone?

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 08, 2015, 02:46:07 pm
content: Quote from: arto on February 08, 2015, 02:27:36 pmYou haven't really given us any useful information to work with, only symptoms.The best we can do is to advise you to go back to the drawing board and invent a more stable scheme.
Question regarding the checksum byte of the AM2302/DHT22 sensor - Page 1
Forum section: electronics / projects

author: Kalcifer
author_rank: Regular Contributor
timestamp: May 07, 2022, 09:58:51 pm
content: So from thedatasheetfor the AM2302, it says that the checksum is the sum of each byte of the sent data.For example with received data0000 0010 1001 0010 0000 0001 0000 1101 1010 0010 (the last byte being the checksum)you'd get0000 0010+ 1001 0010+ 0000 0001+ 0000 1101-----------------1010 0010 (matches the checksum byte)What I'm curious about is what happens with the checksum byte if there is an overflow in the sum? I could see something like that happening if there was 25.5% humidity, and 25.5C:0000 0000+ 1111 1111+ 0000 0000+ 1111 1111--------------1 1111 1110As you can see, there is an overflow, so the checksum is no longer a byte in size. How would this be sent as a checksum byte? Would the sensor just send the least significant byte, and ignore the overflow bits? I can't find any information in the datasheet about this.

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 07, 2022, 10:25:14 pm
content: You get 8-bit, always, the rest is discarded.The checksum of 0xFF+0x01 would be 0.1111 1111+ 0000 0001= 1 0000 0000Chk: 0000 0000

author: bson
author_rank: Unknown
timestamp: May 07, 2022, 11:18:51 pm
content: Sometimes the checksum can't be 0 and it rolls over from 0xff to 0x01.
(solved) question reguarding old style ceramic capacitors (dogbone?) - Page 1
Forum section: electronics / projects

author: whitevamp
author_rank: Regular Contributor
timestamp: July 21, 2016, 03:44:49 am
content: so i was hoping that someone here wiser then me, and possible a grey beard. might be able to help me out on this question.so i have a bunch of these old style capacitors ( or that's what i think they are, if my googlefu is not failing me. ) that from looking appear to be called dogbone ceramic style capacitors.is this correct.PS: yes i have tried to measure them but they are too low for my meter to read.

author: firehopper
author_rank: Frequent Contributor
timestamp: July 21, 2016, 08:17:00 am
content: they may be resistors too..

author: MagicSmoker
author_rank: Super Contributor
timestamp: July 21, 2016, 10:17:25 am
content: Yes, that is an old "dogbone" style capacitor. Scroll down this page to translate the color code:http://www.pmel.org/Handbook/HBpage26.htmEDIT: upon looking at that page more closely I can see it might be difficult to understand since the stripe order legend is messed up. This page has a less-than-sharp reproduction of a color code decoder but it is more intelligible:

author: whitevamp
author_rank: Regular Contributor
timestamp: July 21, 2016, 02:12:02 pm
content: thank youfirehopperandMagicSmoker
Question related simple step-up converter for 2 x AA battery  - Page 1
Forum section: electronics / projects

author: Frank_MV
author_rank: Regular Contributor
timestamp: March 03, 2021, 07:07:26 pm
content: Hello experts,I have already posted my question here:https://www.eevblog.com/forum/embedded-computing/step-up-converter-for-arduino-battery-operation/But I'm not sure if this is "embedded-computing" the right subforum and unfortunately my question still remains unanswered, so I'll put it here again, since there are also blogs about step-up converters here.Thanks,Frank
Question to other AADE LC meter owners - Page 1
Forum section: electronics / projects

author: SmallWalrus
author_rank: Contributor
timestamp: February 28, 2012, 11:16:57 pm
content: Hi all,I have just ordered for myself a kit for AADE's LC meter, and was reading through the instruction manual to get a hang of what's involved to get it together.One thing I noticed as I was going through the parts list is that the design consisted of a pair of 2 capacitors, C2a and C2b, of which the total capacitance is vital to the operation of this thing.I was actually considering swopping the capacitors out for some higher quality ones Wimas, but I guess I won't be able to do it now.I don't like a tool that I don't understand how it works, it seems like the meter will potentially go "off" calibration after some time (http://www.cliftonlaboratories.com/aade_l_c_iib_meter_review.htm), and since I am assuming Neil is also a fairly old gentleman, it might leave me with a meter that I am unable to troubleshoot or recalibrate in the future!Does anyone know the mystery behind the values of C2a and C2b? How are their values determined?

author: T4P
author_rank: Super Contributor
timestamp: February 29, 2012, 11:22:52 am
content: *referring to the majority on diystompboxes*Why is everyone so arse-filled to the face to change any caps straight away to Wima's ?Does it guarantee instant performance increase ? NO !You don't know how the circuit works and you don't know how ESR affects , why would people want to change to wima's ?So don't unnecessarily immediately grab a wima cap !Prove me in ways a wima cap is better then the equivalent , other then ESR obviousity .

author: wkb
author_rank: Super Contributor
timestamp: February 29, 2012, 01:34:38 pm
content: Quote from: Dave.S on February 29, 2012, 11:22:52 amThat, and I find it kinda 'typical' at best to compare a high-end bench meter with the AADE DIY unit. You can probably buy like 20 to 100 AADE units for the price of that HP kit. Of for the price of one of those reference caps shown in that report.Use it for what it is intended and you are OK. I homegrew an AADE-like LC meter myself, and it works OK enough.If you are into metrology go work at NIST and steer clear of DIY meters like this
Question: What makes triacs fail - Page 1
Forum section: electronics / projects

author: Raj
author_rank: Frequent Contributor
timestamp: September 22, 2018, 04:26:00 pm
content: I've seen many triacs failing short after very long use period under medium currents. What makes them go bad all of a sudden? Is it preventable?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 22, 2018, 04:30:46 pm
content: Overvoltage I would guess.Tim

author: SeanB
author_rank: Super Contributor
timestamp: September 22, 2018, 04:43:57 pm
content: Triacs are some of the most reliable semiconductor devices around, in my experience the only thing that kills them for sure is overcurrent. Generally that comes from incandescent lamp loads where the lamp goes short circuit as part of the failure mode, before blowing open circuit, and this current pulse blows the triac out. Another is them running hot for long periods, and cooking themselves, or being subject to thermal cycling for long periods and the die detaching inside, again cooking it, here the poor heatsink accelerates this, running the device through massive stress cycles. If it is getting hot enough to discolour the SRBP board they will eventually fail, and if it is getting hot enough to crystallise the solder even sooner, very common in light dimmers that run at near smoking temperature at part output.They also can go insensitive, and need more than the rated must trigger current to turn on, or go leaky from gate to the common terminal. Another is very high dVdt pulses applied to unsnubbed devices, partly turning the device on and then part of the die runs very hot carrying the load current briefly, causing the device to eventually go short circuit.Otherwise they always want to turn on, so they limit energy in them well, shifting it to the load side. Voltage spikes just result in unwanted triggering, so they are to a large part insensitive to this, but the fast spikes can kill them, as they simply cannot turn on fast enough.To keep them with a long life just run them cool, add a snubber ( even those that say snubberless benefit from this) across the device, and add current limiting inductance to keep the fault current within the ratings for single cycle, and drive with enough gate current ( not the minimum gate current, but the typical current, avoid the max current as that causes heating on die) to turn them on fast and hard.
Questions about 34970A, modules, and relay lifetime ... - Page 1
Forum section: electronics / projects

author: mossygreen
author_rank: Contributor
timestamp: January 25, 2021, 09:57:44 pm
content: I have a 34970A and 2 34901A modules that I purchased about 12 years ago as my employer was folding. The things have sat idle in indoor conditioned space since that time. I am about to do a little test and got to looking in more detail at what I had. Everything powers up, passes self tests, responds to GPIB commands, thermocouples give "correct" readings, etc.Fundamentally I'm trying to understand what to expect w/r to relay lifetimes in this application. Reading the manual and datasheet give some info, but I lack the practical understanding of what unloaded vs. very lightly loaded means, etc. The plots of the impedance of the relays are very steep so it looks like things could just fall apart in the span of a few thousand relay switch cycles. However, I don't see people talking about cycle counts for used modules, etc.The mux itself and one of the two modules was used in some thermal testing. Using the SCPI interface I get this for the DMM's relay counts:2667053,1424003,2667338The more lightly used module gives this for the channels:2874293, 2874291, 2874264, 1, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0and this for the other relays within the module:0, 0, 0, 0, 2874285, 017 of the channels have no use but three have ~2.8M cycles on them. If these were used for thermocouples and RTD's, am I likely okay for a while for the same kind of usage?I can see some diagrams in the service guide with a suggestion as to how to disassemble a 34901 module and there are part numbers for the relays. Is that something people do themselves, or do most people trade-in their used modules and get refurbished ones?How long do the internal DMM relays last? Is their aging just calibrated out?Any guidance appreciated ...

author: CaptDon
author_rank: Super Contributor
timestamp: January 26, 2021, 03:24:29 pm
content: We have a large number of these HP acquisition units where I work. Some have been in constant use for at least a decade. It seems our most common failure is loose connections and sometimes having to pull the module out and plug it back in which I will guess is only to breakdown oxidation at the edge connections. There was always a concern about 'dry switching' with less than 10ma of current flow but I think the internal relays use some sort of wiping action to get around dry switching since we never really seem to have any problems even with thermocouples which have microamps of current flow.
Questions about Allan Variance for INS ( Gyroscope, Accelerometer ) - Page 1
Forum section: electronics / projects

author: ammjy
author_rank: Regular Contributor
timestamp: March 31, 2019, 03:37:37 pm
content: Hello, EEVBlog peoples !Always Thanks you for your help.in this moment, i should calculate the Allan Variance from logging data of INS to estimate error.i recorded Gyroscope and Accelerometer, Temperature datas for 97 minute without any movement.and now i following Matlab reference to obtain Tau-sigma graph.(https://kr.mathworks.com/help/fusion/examples/inertial-sensor-noise-analysis-using-allan-variance.html)Sampling time is 97.1061 minute. (from 91.98 sec till 5918.346 sec)Total number(length) of data is 836185.but, i can't understand what is aFs.Anyone know about it ?i attached screenshot of page.(That page support Example for that. but, unfortunately, my student version Matlab 2017b has not that example... )Please, let me know !

author: awallin
author_rank: Frequent Contributor
timestamp: March 31, 2019, 03:53:48 pm
content: Fs is the sample-rate, and its inverse t0=1/Fs is the time-interval between data points.

author: ammjy
author_rank: Regular Contributor
timestamp: March 31, 2019, 03:59:39 pm
content: Thanks you for your time, Awallin.then, might be i can use recorded time data to sample rate FS !Regard,ammjy

author: awallin
author_rank: Frequent Contributor
timestamp: March 31, 2019, 04:29:53 pm
content: Quote from: ammjy on March 31, 2019, 03:59:39 pmt0 = "recorded time 97mins" / "number of data points"Fs = 1/t0

author: ammjy
author_rank: Regular Contributor
timestamp: April 01, 2019, 05:53:47 am
content: Good day, Awallin !thanks to, i got result.i appreciate for your kind help, again !
Questions about bench setup... - Page 1
Forum section: electronics / projects

author: DaveHardy
author_rank: Regular Contributor
timestamp: March 29, 2013, 02:24:08 am
content: Hey, I just started a new job this week and figured out that my bench was completely floating today; there is no ground return path. Is this safe or customary in the industry? What is the point of setting up a bench like this?

author: nanofrog
author_rank: Super Contributor
timestamp: March 29, 2013, 04:17:52 am
content: Where are you located?Have you asked your employer about the specifics (perhaps there was a particular reason and the ground was disconnected)?It's not as safe (easier to blow your equipment if it's floating and/or injure you), and from what I've seen/understand, not customary in the US at least (wouldn't expect it to be in other parts of the world either).Assuming you're in the US, How old is the building?I ask, as the NEC passed outlet grounding (ground the metal box) in October 1958. So if the building is old enough and hasn't been updated, ground won't be present in the receptacle at all. If it's 1959 or newer, there may have a loose ground connection in the structural wiring (assuming it wasn't intentionally disconnected).
Questions about British Telecom modular plugs - Page 1
Forum section: electronics / projects

author: ledtester
author_rank: Super Contributor
timestamp: July 10, 2021, 09:17:57 pm
content: The Vernier Labquest devices use British Telecom (BT) modular plugs for connecting sensors to their data acquisition devices:https://www.vernier.com/til/5457and they refer to them as "BT Analog (Right Hand)" and "BT Digital (Left Hand)".They sell pre-made cable assemblies:https://www.vernier.com/til/818but I'd like to make my own.My questions are:- Does anyone know of a source for these modular plugs?- Can I use a BT Analog plug in a BT Digital socket if I snip off the retaining clip? (Of course I'll have to find another way to hold the plug in.)- How would I go about creating a custom cable assembly once I have these plugs? Is it just like with RJ11 plugs -- i.e. there are grooves for the individual conductors and then you crimp? Is there a special crimping tool I need? I have cheap RJ11 crimping tool.- I found this US ebay listing for "BT 631A BABT/BRITISH TELECOM 631A CONNECTOR":https://www.ebay.com/itm/142653287218Are these what Vernier calls the "BT Analog (Right Handed)" plugs? I'd like to find a source for both the left-handed and right-handed plugs.Thanks!

author: nfmax
author_rank: Super Contributor
timestamp: July 11, 2021, 09:16:58 am
content: The 'analogue' connector is the one currently used in the UK analogue phone system, the 6-pin variant of which, I gather from Wikipedia,https://en.wikipedia.org/wiki/British_telephone_socketis called the BT631A. The 'digital' variant is much less commonly used, and is called the 630A. The 4 pin variants of theses connectors are exactly the same size & shape, but have only 4 contacts populated: they are types BT431A & BT430A. You will need a special crimping tool, or a die set for a suitable universal tool, to fit them to your own cable. It may be simpler to but ready-made phone leads and 'adapt' them. I found a selection of BT631A leads at Farnell (part of Newark)https://uk.farnell.com/w/c/cable-wire-cable-assemblies/cable-assemblies/telephone-cables?connector-to-connector=bt631a-plug-to-bt631a-plug|bt631a-plug-to-bt631a-receptacle|bt631a-plug-to-rj12-plug. I also found suppliers for both types of connector, searching using the connector type number, mostly UK-based as you would expect.

author: ledtester
author_rank: Super Contributor
timestamp: July 19, 2021, 06:24:57 pm
content: Thanks! I ordered some cable assemblies from Newark and it seems they will ship them from their UK warehouse at no extra cost. Not only that, but the Newark price is even cheaper than than the Farnell price!Moreover, my order contained items split between the US and UK and I was just notified that my US items have already shipped. That's quite a bit of service for only $10 in shipping!

author: Gyro
author_rank: Super Contributor
timestamp: July 19, 2021, 07:17:33 pm
content: I wish it worked that well in the other direction!
Questions about  Critical conduction mode PFC controllers - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: November 16, 2017, 11:17:43 am
content: Hello,In light load, BCM boosts go to high frequency.This should be limited by the controller.Why does the L6562 datasheet not give the minimum off time?(its a fixed off time controller)L6562 datasheethttp://www.st.com/content/ccc/resour...CD00003316.pdf------------------------------------------------------------------------------------------Page 16 of the L6562A BCM Boost PFC controller datasheet states that a bias winding is not necessary for the L6562A.....and a simple “RC method” can be used instead...........why does it say that the ‘RC method’ even works when the mains peak voltage is just below the output voltage?......why bother to state this?, i mean, why wouldn’t it work in that situation?......and even if vout was lower than mains peak, ...so what?.......would that mean that the "RC method" would not work?...and that a bias winding would be needed?L6562Ahttp://www.st.com/content/ccc/resour...CD00151385.pdf------------------------------------------------------------------------------------------------------The following st.com application note shows an L6562A being operated in simple constant off time mode..........This allows us to have a settable maximum operating frequency.....so no matter how light the load goes, the operating frequency does not get ridiculously high.I cannot understand why they only offer this use of the L6562A as a sort of aside....i mean, its clearly better than the “usual” Critical conduction mode method of operation. Why is constant off time mode not the main method of control for the L6562A?L6562A in constant off time mode App note.http://www.st.com/content/ccc/resource/technical/document/application_note/dd/ab/71/7a/f9/cc/43/c2/CD00195418.pdf/files/CD00195418.pdf/jcr:content/translations/en.CD00195418.pdf---------------------------------------------------------------------------------
Questions about LM2596 Buck Converter - Page 1
Forum section: electronics / projects

author: ElectricPower
author_rank: Frequent Contributor
timestamp: November 20, 2019, 06:16:23 am
content: 1. I have read that its possible to add heat sink to LM2596 to make it give som more current output. Is this a simple task to do? If yes...how?2. I have an power adapter from an old laptop that gives 20V and 4.2amp. Can i safely connect it to LM2596? I know that max theoretical output still is 3amp (theoretical) but can i use that adapter anyway?

author: wraper
author_rank: Unknown
timestamp: November 20, 2019, 06:57:01 am
content: Are you talking about very cheap fake LM2596 modules from China?

author: ElectricPower
author_rank: Frequent Contributor
timestamp: November 20, 2019, 06:58:43 am
content: I think so... ibought it frem AliExpress. It is an LM2596S (with LED display). I think it cost me 1.20$.It is this one i ordered:https://www.aliexpress.com/item/32825777330.html?spm=a2g0s.9042311.0.0.3fe34c4dQxQQSZ

author: wraper
author_rank: Unknown
timestamp: November 20, 2019, 07:25:06 am
content: Then it has nothing to do with real LM2596. They work at much lower frequency and actual specifications are not known.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 20, 2019, 07:27:10 am
content: Try it. If it blows, you're out a buck and a counterfeit chip.Tim

author: ElectricPower
author_rank: Frequent Contributor
timestamp: November 20, 2019, 07:47:55 am
content: I see.But generally... can i connect a power adapter with 20v. and 4 amps as input til this converter? I suppose it's okey as long i do not uses that power in the other end?
Questions about load compensation circuit - Page 1
Forum section: electronics / projects

author: Warsp
author_rank: Contributor
timestamp: April 14, 2025, 08:58:06 am
content: Hi all,While looking for sample circuits to reference while designing my adjustable load, I came across this constant voltage controller in the HP 6060 manual. I understand the basic idea of what it does: it outputs a voltage that makes the magnitude of the negative voltage feedback signal equal the programming voltage by making the sum of the two equal 0V, but I have a few questions about the compensation capacitors and resistors.1. Why were these components needed? I know that a single capacitor and resistor could be used to remove unwanted frequencies and to control how fast the opamp responds, but why did the HP engineers decide to use so many components. Was this to improve phase or gain margins?2. How did they choose these particular values? If this is a compensator circuit used to improve phase and gain margins, did they already know what poles and zeros they needed, or did they just pick ones that seemed about right?3. Couldn't the 6 compensation capacitors and resistors be simplified down to a single capacitor and resistor? How does using multiple make a difference?I am currently trying to design my own constant voltage load, so I would like to know if I should put something like this in my design. Thanks!

author: Someone
author_rank: Super Contributor
timestamp: April 14, 2025, 09:57:30 am
content: This is an old trick for loop compensation where you can push the 90 degree phase shift to a much higher frequency, at the cost of a slightly slower roll-off.

author: David Hess
author_rank: Super Contributor
timestamp: April 14, 2025, 11:03:18 am
content: Single pole compensation would result in 90 degrees of phase lag, leaving only 90 degrees total for the operational amplifier's phase margin. The network implements an integrator with 45 degrees of phase lag and 3dB per octave of roll-off, increasing the phase margin by 45 degrees to better handle difficult loads.
Questions about low voltage differential amplifiers (100-200MHz) - Page 1
Forum section: electronics / projects

author: Plasmateur
author_rank: Regular Contributor
timestamp: December 28, 2016, 04:02:34 pm
content: I need quite a few differential amplifiers for a project I'm working on.+/- 100 volts100-200MHz bandwidthI need them for what is shown in page two of the following pdf:http://plasma.physics.ucla.edu/papers/Everson-RSI-Bdot.pdf, as well as higher voltage applicationsI started looking at simple diff amp configurations such as what is shown here:https://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Op-Amp_Differential_Amplifier.svg/280px-Op-Amp_Differential_Amplifier.svg.pngBut it appears something like this probably wouldn't work for the frequencies I need as I noticed the DIY differential probe designs have capacitors incorporated into them. I'm not sure as to why this is the case.Could anyone point me in the right direction?
Questions about modding a BGA rework station. - Page 1
Forum section: electronics / projects

author: Spork Schivago
author_rank: Frequent Contributor
timestamp: July 06, 2016, 11:20:24 pm
content: Hello,I have a need to mod my rework station. It has an infrared preheater and then hot air for the BGA component. I'm replacing the ceramic heating elements. The new ones have shorter wires. Could someone tell me if I could safely move these junction type boxes a bit closer? I've already moved one so I could wire up some new IR heating elements, but I have to move more. I think in the end, I'm going to have to move all of them. I drew a red box around them so you'd know what I'm talking about. All they seem to do is actually allow a wire to be connected to one or more wire(s). So, what do you guys think? Safe to move them a little closer to the heating elements or no? Thanks!
Questions about power selector switch MAX14714 - Page 1
Forum section: electronics / projects

author: bhj99
author_rank: Contributor
timestamp: January 25, 2025, 05:48:49 pm
content: Hello, I am currently working on a PCB design that will potentially connect with a mezzanine board. One of my requirements is that this host PCB should be able to source or sink current for the 3.3V power rail to/from the mezzanine. I am thinking about using the MAX14714, since the datasheet claims bidirectional power paths (i.e. if host sources 3.3V the switch will select from IN1 (or IN2) to OUT and if the mezzanine sources 3.3V then the switch will operate from OUT to an IN1 (or IN2) path depending on the how the Enables are configured).Some questions I am hoping to get some insight on:1. Is this a correct understanding on how the MAX14714 could operate?2. If there's a situation where there is 3.3V power delivered to the OUT pin and there is power on IN1 (also at 3.3V) but IN2 is 0V and both EN1/EN2 were low (both enabled), how would the MAX14714 operate?Appreciate any help with this. Thanks!
Questions about rectifiers - Page 1
Forum section: electronics / projects

author: okest
author_rank: Newbie
timestamp: November 16, 2017, 07:18:08 am
content: Hello,I need to create an variable voltage power supply(AC->DC) with output from around 3V to around 50V(around those voltage levels) and nominal max current of 7A(so i was thinking maybe rating the supply for 10A would be good enough).I was thinking of using variable autotransformer with 1500VA rating and a KBPC5010F 1000V 50A diode bridge and using caps to filter the output a little. Since the variable autotransformer steps would be too steep i think(adjustable from 0-250V) i was thinking of using another transformer with like 230V->110V feeding it straight from variable autotransformer. What problems would i run into and do you have any suggestions on what should i do before i go buying stuff and finding out the hard way?

author: jaycee
author_rank: Regular Contributor
timestamp: November 16, 2017, 08:39:49 pm
content: An autotransformer would provide no isolation from the line voltage, and would be incredibly dangerous to use as a bench supply

author: jaromir
author_rank: Unknown
timestamp: November 16, 2017, 08:59:14 pm
content: Quote from: jaycee on November 16, 2017, 08:39:49 pmThat's why the 230->110V transformer proposed by OP would help. With both voltage range, as well as isolation from mains.

author: Ian.M
author_rank: Super Contributor
timestamp: November 16, 2017, 09:09:25 pm
content: Better a 230V to 55V transformer. A bridge rectifier feeding a capacitor only delivers 2/3 the DC amps of its AC RMS input current, so for 7A out, you need a minimum of a 10.5A transformer secondary, which at 55V is 578VA, a 600VA transformer will have a little margin. Use a 110V output transformer and it will need to be 1200VA which wlll be a lot more expensive. Also the lower voltage gives you more control range.

author: Cyberdragon
author_rank: Super Contributor
timestamp: November 16, 2017, 09:20:55 pm
content: Why on Earth do you need a 50KW rectifier for a 350W power supply?!That seems incredibly excessive. Or am I misunderstanding something...

author: Ian.M
author_rank: Super Contributor
timestamp: November 16, 2017, 09:29:55 pm
content: Well if you've got it sitting on the shelf . . .. .

author: Gyro
author_rank: Super Contributor
timestamp: November 16, 2017, 09:31:03 pm
content: Quote from: Cyberdragon on November 16, 2017, 09:20:55 pmIt's not a 50kW rectifier. It's a 50A rectifier with a reverse standoff of 1000V. You wouldn't describe a 1N4007 as a 1kWdioderectifier.Admittedly it is a bit high rated - not excessively so for OP's original idea of 0 - 250V. Obviously for a 0 - 55V as suggested by Ian.M the voltage rating could be dropped to, say, 200V and the current to maybe 20A (if it's going to be driving a capacitive load).
questions about Savonius turbine.  - Page 1
Forum section: electronics / projects

author: fantis1337
author_rank: Contributor
timestamp: March 10, 2016, 05:49:09 pm
content: I'm building a Savonius turbine from scratch in my next ten week course which starts two weeks from now. I'm wondering if anyone here has experience they would like to share?The turbine does not have to meet any specifications regards to power or anything like that but it has to look nice since it's going to be on show at some point. I was thinking of doing the scoops out of 4-6mm acrylic and having as much of see-through as possible. When it comes to the power generation should I be directing the rotation directly by gears or by belt?As you can probably see I have no idea what I'm talking about but I have the first two weeks to do research and I'd take some input so I know what i'll be looking for when it comes to it.
Questions about TI TSW1400EVM Error 5000 on HSDC Pro - Page 1
Forum section: electronics / projects

author: ZhongJun
author_rank: Newbie
timestamp: June 16, 2024, 03:26:27 am
content: I have TSW1400EVM evaluation board and a AFE58JD48EVM evaluation board from Texas Instruments,and I connected them together to use it.IMG_4014.jpg(4445.98 kB. 3956x2505 - viewed 48 times.)But Error 5000 occurred when I used TI High Speed Data Converter Pro to update the firmware of AFE58JD48.IMG_4012.jpg(2834.32 kB. 4032x3024 - viewed 38 times.)I have searched the solution of this issue on the TI E2E website but didn't solve my problem.I'd like to ask if anyone had meet this problem,and we can discuss the solution.
Questions on high-speed USB & HDMI design (TMDS,CML,LVDS,PCIE, etc.) - Page 1
Forum section: electronics / projects

author: byte
author_rank: Contributor
timestamp: November 12, 2021, 03:25:28 pm
content: Hello,I'm currently planning a complex (for me) hobby project. This will be my first time creating a design with highspeed differential and USB / HDMI signaling.I have some questions if someone who has experience will be so kind to answer. (And yes, I've spend hours and hours researching this myself, but still have these questions)HDMI (TMDS) uses CML for the differential pairs. But what standard does USBC (Superspeed, superspeed+) use?Do alternate modes change the signaling standard used in usbc? E.g. with DisplayPort alt mode, does it use the superspeed signaling standard* or the Displayport signaling standard?My understanding is the thunderbolt 3.0 alt mode passes through 4 PCIE 3.0 lanes over TX1,TX2,RX1,RX2. I assume these each become bidirectional, but again, does it use the PCIE 3.0 signaling standard or superspeed standard*?Are there any ICs out there to take a bi-directional differential link and split it into two unidirectional differential pairs? My application is a specialized fiber transceiver for USB/HDMI and I'll need to convert the bidirectional D+/D-, SBUS+,SBUS- and PCIE alt mode lanes to unidirectional.I have and can only afford a 1Ghz/10GS scope. Are there any USB/HDMI compliance testing labs in the US that are affordable for a hobbyist to verify designs?* By superspeed standard, I mean the signaling itself e.g. CML,LVDS,etc. I'm not that worried at the moment about serdes scrambling and encoding schemes. For now I'm just trying to figure out how to design the physical interface.Thanks in advance!

author: byte
author_rank: Contributor
timestamp: November 20, 2021, 05:25:06 pm
content: Any one worked with these high speed standards?
Questions on JLCPCB - Page 1
Forum section: electronics / projects

author: criznach
author_rank: Newbie
timestamp: July 30, 2018, 05:38:17 pm
content: I've ordered a few things from JLC with decent results and am looking to try a more complex, PCB artwork design. I'll need routed, curved outlines and some slots. And I'd also like to be able to hand-solder some SMD LEDs on the board's edge. So I have some questions...It looks like 2mm is their routing width based on their capabilities page. Can they do smaller, and/or does it cost more? I was hoping to make some 1.6 (or so) slots for joining boards. If I can only get 2mm, I'll wiggle or zig-zag the slots to make 1.6 fit tightly.If I ignore DRC errors, can routing go through a copper pour or pad? I'd like large-ish pads at the slot edges for joining boards together at 90 degree angles.And again, ignoring DRC errors, can I cut plated holes (both round and oval) in half with the edge routing layer? This is how I planned to edge-mount SMD LEDs.If I omit the solder mask over an area on both sides, does the PCB material appear brownish? It's hard to tell from the boards I have with full solder mask.Thanks!

author: innkeeper
author_rank: Unknown
timestamp: August 04, 2018, 03:00:43 pm
content: think that's a question best asked directly to JLPCB.If you get an answer from them, please post. It is good information to know.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: August 04, 2018, 03:56:42 pm
content: QuoteThat sounds like it is not really a DRC error in the eyes of the manufacturer. Even in most PCB tools you can turn that off so it is not a error by for example connecting the pour or pad to the same net as the routing so it no longer counts as a 'short'.QuoteDo you mean over copper or over bare substrate? Substrate is usually FR4, and I don't think JLC can do anything else (at least not for their cheap 2 dollar boards). It should look like any other FR4, and will be something similar to this:Source:http://www.gar-fond.com/english/unclad-fr4.htmlAs for the other two: You should contact the manufacturer on this.