hybridfree/eevblog-posts huggingface dataset:
What foorprint/PCB copper does SMD resistor need to dissipate 1W? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 12, 2022, 09:51:36 pm
content: Hi,What footpring would this resistor need to be able to dissipate 1W?RCWE1020R332FKEAhttps://www.vishay.com/docs/20019/rcwe.pdfWe have three of them each dissipating 1W (500ww PFC sense resistor)...they are next to each other on the PCB, and are on bare minimum footprints, no thermal Cu pour or thermal vias.Vishay website gives no data for this resistor.

author: dmills
author_rank: Super Contributor
timestamp: November 12, 2022, 10:46:58 pm
content: Watch the derating curve on these, it claims to be ambient temperature but I think it is probably PCB substrate temperature.I would definitely be doing a few experiments, 3W in a (effectively) 1812 is a big ask and I am not at all sure I buy it.Also, running any component at 100% of rating? Really? This is the way to exploding streetlighting ballasts, a subject that I think you may have some expertise in!

author: Faringdon
author_rank: Super Contributor
timestamp: November 12, 2022, 10:58:42 pm
content: Thanks, i used to have a SMD power resistor App Note which showed how much extra copper pouring was needed round a 2512, 1W resistor , for it to be able to actually dissipate 1W without burning up...but i have lost it now.From what i remember, the 2512 needed to be on a two layer PCB, and in the middle of 2cm x 2cm of copper pour, on both top and bottom.....and to be thermally via'd to the bottom ones, and each pad directly connected to half of each side's copper.A 2512 is good for maybe 350mW if on minimum pads and at 40degc ambient, i think?

author: jonpaul
author_rank: Super Contributor
timestamp: November 15, 2022, 02:49:17 pm
content: avoid SMD hi power R, use TH, available in 2,5,10w and up.j

author: M0HZH
author_rank: Regular Contributor
timestamp: November 15, 2022, 04:54:26 pm
content: I use 2512 dissipating around 650mW each in some of my RF designs. One end is connected to a large copper pour on the top side and a heatsink on the bottom (3 vias connecting top and bottom). The temperature rise is quite low, maybe 15C above PCB/heatsink temp, they could handle ~2W I think.I also use a single 2510 zero-ohm to pass 600W of RF power at 50MHz into 50ohm load.

author: Faringdon
author_rank: Super Contributor
timestamp: November 16, 2022, 05:25:35 am
content: QuoteThankyou, this seems typical, ie, 2512 on min pads could not be used to dissipate your 650mW.
RM6 based offline flyback cannot pass mains isolation test? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 10, 2022, 05:48:02 pm
content: Hi,Do you agree, an RM6 based offline flyback for 115VAC cannot pass isolation testing of "2500VAC for one minute"?The secondary windings, when terminated to those pins, is too close... , ..basically, since the pins themselves are too close to the primary windings on the RM6 bobbin?RM6 BobbinB65808N1006D001https://www.tdk-electronics.tdk.com/inf/80/db/fer/rm_6.pdfDo you know of any list of standard ferrite bobbins which cannot pass "2500VAC for one minute"?

author: Kleinstein
author_rank: Super Contributor
timestamp: November 10, 2022, 05:56:47 pm
content: AFAIK the pins don't reach through to the winding side. So it should be possible to keep enough distance. Worst case consider potting with good dielectric strenght as a last resort - chances are you could get to the 20 kV range this way.

author: jonpaul
author_rank: Super Contributor
timestamp: November 11, 2022, 02:51:46 pm
content: We designd and shipped 7000 PSU in 1980s, based on RM6, RM8advise...avoid RM6 at all cost!delicate, not rated for line safety, pins breakUse modern shape with split bobbinj
Pure Sine Wave  Inverter ?  - Page 1
Forum section: electronics / general

author: Hundleton1
author_rank: Contributor
timestamp: November 10, 2022, 10:08:13 pm
content: Hi folks, this inverter unit in a power station is listed a pure sign wave model. What’s people’s thoughts on the output ?Not sure I’d class that at pure

author: KaneTW
author_rank: Frequent Contributor
timestamp: November 10, 2022, 10:58:43 pm
content: I'd consider it a pure sine wave if it's not worse than mains, i.e. 8% THD max.

author: Marco
author_rank: Super Contributor
timestamp: November 10, 2022, 11:05:45 pm
content: Is this loaded with anything except the scope?

author: Hundleton1
author_rank: Contributor
timestamp: November 10, 2022, 11:08:18 pm
content: Yea loaded at 50w

author: edtyler
author_rank: Contributor
timestamp: November 11, 2022, 02:53:12 am
content: What type of probing solution are you using?I see a waveform a lot like this when using a McSig differential probe set at too low a scale. If switched to the 700V scale, the waveform looks OK.

author: Hundleton1
author_rank: Contributor
timestamp: November 11, 2022, 07:54:58 am
content: Hold on, you may have hit the nail on the head. It was a Micsig Diff probe. I may have been on 50x actually. I can’t recall the levels for 50x.May be a schoolboy error here 🤔🤦‍♂️
Offline 115VAC, 3W Flyback, wound with 0.1mm enamelled copper wire? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 10, 2022, 05:59:58 pm
content: Hi,We have been given by a cust, an offline 115VAC flyback transformer, which is 20:1:1Core is TDK RM6, with TDK bobbin. (B65808N1006D001)Windings:Primary is 200 turns of 0.1mm enamelled copper wire (4 layers total, 50 turns per layer)Secondary is 10 turns of 0.1mm enamelled copper wire.Auxiliary is 10 turns of 0.1mm enamelled copper wire.The Sec and Aux are both 12VSec and Aux are bifilar wound in one layer, with evenly spaced turns across bobbin winding width.{PRI__SEC & AUX bifilar wound___PRI}Tape between layers.There is no margin tape so we know it wouldnt pass creepage regs....there is no room for margin tape with RM6 in this case. (for their prototype they didnt want to bother with margin tape/regulations as only they will touch it.)None of the enamelled copper wire of 0.1mm diam has any kind of voltage withstand spec eghttps://www.digikey.co.uk/en/products/detail/adafruit-industries-llc/3522/7393587?s=N4IgTCBcDaIKYDsCGBbOAbdcAmACAxgPYAOxcATrgO4CW5cIAugL5ADo you think it may suffer flashover.?..since the thinner is the ECW, the lower is its voltage rating...https://www.elektrisola.com/Attachments/TechnicalData/enamelled_copper_wire_english.pdf...this doc shows that Grade 1, 0.1mm ECW has a breakdown voltage of 500V....and the Drain voltage of the flyback will go up to just above 500V.If you buy 0.1mm ECW, you've no datasheet that shows what grade it is....such data does not exist for 0.1mm ECW.

author: jonpaul
author_rank: Super Contributor
timestamp: November 10, 2022, 06:05:23 pm
content: Bonjour, RM6 s a poor shape for modern design"Enamel" = 100s types need exact wire spec eg heavy nylease, single formvar, HPTZ.interlayer insulation?Please entire winding sheet of part.Jon

author: Faringdon
author_rank: Super Contributor
timestamp: November 10, 2022, 06:15:26 pm
content: QuoteBonsoir, Merci, Sorry cust wont let me post their work.I edited the top post to show windings configuration better.

author: jonpaul
author_rank: Super Contributor
timestamp: November 10, 2022, 07:57:21 pm
content: will fail strike/creep/VDE/UL/TUV unless SELV.Safety and liability suggest to decline the job or secure 10M$ liability abd E&O insj
Why RAM, rechargeable alkaline manganese, battery simply not available - Page 1
Forum section: electronics / general

author: abdulbadii
author_rank: Frequent Contributor
timestamp: November 10, 2022, 12:38:38 am
content: Why RAM, rechargeable alkaline manganese, battery not practical, ie. simply not available in marketOtherwise it's far so more useful as it is nominal 1.5V

author: james_s
author_rank: Super Contributor
timestamp: November 10, 2022, 12:42:35 am
content: I remember those being a thing for a while. They had a couple of major problems, one being they were only good for about 25 cycles, less if you fully discharged them before charging, next they required a special charger, and finally like other alkaline batteries they were prone to leaking. Modern day NiMH works just fine.

author: ejeffrey
author_rank: Super Contributor
timestamp: November 10, 2022, 03:15:30 am
content: Because low self discharge NiMH got common and cheap. Rechargeable alkalines batteries had a bunch of drawbacks james_s explained but were somewhat popular 15-20 years ago because NiMH had a charge retention of like a few weeks. These days the only thing to recommend them is the voltage compatibility, but in practice almost everything works with NiMH.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 10, 2022, 08:39:52 am
content: Quote from: abdulbadii on November 10, 2022, 12:38:38 amThere is nothing useful in "nominal 1.5V", because actual products do not work with nominal voltages, but actual voltage ranges.And it so happens that the actual voltage range of an alkaline cell is approximately [1.6V .. 0.9V], while the range for NiMH is approx. [1.25V .. 1.0V]. This means, any sensibly designed product must run down to 1.0V, in which case NiMH can be completely utilized. The only issue is in voltage-based battery indicators which show something like 50% and then suddenly run down at the end of discharge, due to the flat discharge curve of NiMH.
"Airborne" PSU details. - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 08, 2022, 06:08:13 pm
content: Hi,We have seen a spec for an Airborne PSU.....115VAC, 60Hz input.....VAC input can go up to 172.5VAC for up to 2 seconds. Max transient said to be 1kV.Its is a PFC'd Full Bridge with vout = 28V and 500W.The 115VAC input first has a fuse followed by an SMCJ180CA TVS. -Surely this TVS is a joke?SMCJ180CA trips anywhere between 180v and 220v, and has max surge current of just 5A, where its 292V......i mean , the 172.5VAC (243 Vpeak) is going to blow it, let alone the 1kV transient....We have been asked to bid for this work (take it to prod) ...but it looks like a "trick bid"...to see if we are dopes?The PFC uses a standad UF diode, and its switching frequency is set to 200kHz....this seems way too high even for 115VAC mains? (Have always kept ~500W PFC less than 100kHz in past).Do you get "Airborne" PSU's at 60Hz?...i thought they were all 400Hz?SMCJ180CAhttps://www.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_smcj_datasheet.pdf.pdf

author: m98
author_rank: Frequent Contributor
timestamp: November 08, 2022, 10:35:46 pm
content: This sounds like a PSU for a ground power unit. So not airborne, but used to power smaller aircraft on the ground, for example during avionics maintenance.

author: Faringdon
author_rank: Super Contributor
timestamp: November 09, 2022, 07:48:18 am
content: Thanks, in USA, (115VAC mains) is it common to run CCM Boost PFCs at switching frequencies of 200kHz?

author: jonpaul
author_rank: Super Contributor
timestamp: November 09, 2022, 09:59:30 pm
content: ask customer for intended environment and applicationsRFQ should include regulations compliance eg DO-160 FAA/USATransorb looks fine, wths your problem?j

author: coppice
author_rank: Super Contributor
timestamp: November 09, 2022, 10:13:22 pm
content: Airborne power is normally 400Hz. For commercial planes some power is converted to 50Hz or 60Hz for the passenger seats to plug in consumer electronics.

author: Faringdon
author_rank: Super Contributor
timestamp: November 10, 2022, 05:33:54 am
content: QuoteIts a 180V bidi TVS, (SMCJ180CA) and will have 60Hz mains of 240Vpk applied to it for 2 seconds. (who knows how many times)The mains is normally 115vac...but can got to 173vac for 2 seconds at a time.QuotePresumably a 500W PSU, with vout = 28vdc wouldnt be plugged into that?
Protection of gate drive on UC3854 PFC chip - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 08, 2022, 07:26:19 am
content: Hi,There is a post on EEVBLOG (this forum) about the recomendation by ti.com for a 3 Amp Schottky to act as protection for the pins of UC3854.I tried site:https://www.eevblog.com/forum/renewable-energy UC3854 PFC Diode protection....but cant find it,Really sorry to ask, but do you know where it may be?Here is the recomendation for 3 Amp diode..(PG 3)https://www.ti.com/lit/an/slua172/slua172.pdf?ts=1667878664966&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUC3854%253Fdcmp%253Ddsproject%2526hqs%253Dsw%2526Also wondered if same applies to UC2818...datasheet says it isUC2818https://www.ti.com/lit/ds/symlink/ucc3818.pdf?ts=1667892523730&ref_url=https%253A%252F%252Fwww.google.com%252F

author: Gyro
author_rank: Super Contributor
timestamp: November 08, 2022, 11:24:22 am
content: You didn't search very hard - a simple search for UC3854 broughtthemup in seconds...https://www.eevblog.com/forum/renewable-energy/diode-clamp-not-needed-for-uc3854-pfc-chip/https://www.eevblog.com/forum/renewable-energy/why-does-pfc-controller-need-large-protection-diodes/Maybe you're trying for 3rd time lucky.
Power Suplly Boschert INC XL60-3601 - Page 1
Forum section: electronics / general

author: oldiled
author_rank: Newbie
timestamp: November 06, 2022, 10:26:08 am
content: Hi guys,Try the electronics in a very good forum.I am looking for a circuit diagram for the Boschert Model XL60-3601 power supply from Boschert inc.Does the company still exist in the US? I believe the company was based in California around 1984.I have a (two) beautiful Kaypro 4/84 computers.With this calculator I learned my basic knowledge in the early days under CPM. I would like to keep a computer in its original condition.The second Kaypro 4/84 has a California dc power supply.Unfortunately, the circuit diagrams for these computers cannot be found anywhere in the world? He who seeks finds. Yes / Yes!I would be happy about an info.Greetings from GermanyKurt

author: kleiner Rainer
author_rank: Regular Contributor
timestamp: November 06, 2022, 10:59:55 am
content: Kurt,try bitsavers.org for information about historic computers, software and components.They have Kaypro service manuals:http://bitsavers.org/pdf/kaypro/There is also some info about Boschert:http://bitsavers.org/pdf/boschert/Software archive:http://bitsavers.org/bits/Kaypro/Have fun!Greetings,RainerBTW the "Vintage Computing" section of this forum is a better place for your request, it seems to me.
Full bridge 500W without PNP turn off? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 12, 2022, 09:34:03 pm
content: Hi,A cust has sent us a 500W Full bridge to bring up.Spec =Vin = 275vdc (with 58vpkpk ripple at 120hz)Fsw = 250kHzVout = 28vThey have used simple pulse transformer gate drive with no PNP turn OFFWhy did they not put in the PNP turn off?……its so much better and hardly any extra cost/components.Can you see any advantage of the non PNP turn off version?LTspice's and jpegs attached.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 12, 2022, 10:10:00 pm
content: The plain diode provides a negative gate voltage which allows a higher dV/dt without unwanted turn on.

author: Faringdon
author_rank: Super Contributor
timestamp: November 12, 2022, 11:04:56 pm
content: QuoteThanks, i ran the sims, and noted as you say, the negative voltage as you say.....thing is, at the point when spurious turn on happens....(ie just as the opposite leg fet turns on).....the gate voltage of the OFF_FET is pretty well zero volts....so that negative gate voltage is not there when its needed....you can see this by running the sims as attached (LTspice).The gate VGS turn off is massively quicker with the PNP turn OFF. Also, the VGS is zero volts when it should be with the PNP..without it..the VGS is getting uncomfortably high...i mean, still low, but higher than would want for an OFF state FET.
EcoFlow Power Kit Review and Teardown - Marco Reps.  - Page 1
Forum section: electronics / general

author: Black Phoenix
author_rank: Super Contributor
timestamp: October 27, 2022, 01:30:23 am
content: https://youtu.be/eVXz8k_cmGw

author: ataradov
author_rank: Super Contributor
timestamp: October 27, 2022, 02:51:45 am
content: I'm starting to hate this EcoFlow stuff with passion. Marketing is good when it is here and there, but when it overruns all the channels for weeks and months, you start to suspect that their stuff is not selling otherwise.
Converting a 10s LLC (TEA19161-based) charger to 12s - Page 1
Forum section: electronics / general

author: abyrvalg
author_rank: Frequent Contributor
timestamp: October 25, 2022, 12:22:52 pm
content: The story: several eScooter community members are trying to convert a Ninebot 5A 10s eScooter charger to 12s. The idea is to raise the output voltage 1.2x and lower the current limit by the same 1.2x to not exceed the original power rating. We’ve done that successfully on a smaller "traditional" flyback 1.7A charger (adjusting CC and CV setpoint dividers, replacing some output caps with higher voltage ones), but this bigger 5A one is based on a smarter TEA19161 resonant converter controller with many protection modes and it looks like we are hitting the OPP (over-power protection) for some reason I don’t understand (this is my first encounter with an LLC converter).What we’ve done already: identified and adjusted both CV and CC setpoint dividers (there is an AP4310 controlling CC/CV and driving the optocoupler feedback to TEA) and TEA’s OVP setpoint divider (it senses the output voltage from a small auxiliary winding). With 49.8V/4A (1.2x voltage, less than 1/1.2x current) settings the charger worked fine in the lower voltage CC region, but entered an OPP restart loop near 80% of the battery SoC. With the SoC closer to 100% (charged with a different charger) the charger resumes normal operation. We’ve tried lowering the CC setpoint even more and have found a stable operating point around 3.3-3.4A, well below our initial expectations of at least 4A.The next thing we’ve tried was OPP setpoint adjustment. There is no direct Watts setting, the Rsnsset resistor selects either "150%" or "200%" power limit (here I don’t understand what is the base value for these %), the original configuration is 150%. With the resistor changed to 200% the OPP doesn’t trigger anymore, we’ve achieved a stable 3.9A@50V with 215W primary side consumption - doesn’t look like something abnormally inefficient.TEA19161 datasheet says that OPP is triggered based on the resonant capacitor voltage measurement. Do we need to tune this part somehow (scale the cap?) to shift the normal operation range somewhere? Or just keep the 200% OPP setting? Or is that something hitting the transformer limits and we should forget about higher power and be happy at 3.4A?

author: Faringdon
author_rank: Super Contributor
timestamp: October 25, 2022, 08:41:55 pm
content: Yes, you cant do it with LLC so easily.To see whats happening when you connect a 12S...change the vout source in the attached LTspice sim to ~50V...and watch your charge current vanish.......in practice the LLC will try and reduce its f(sw) so that it can serve the higher voltage....but maybe it hits the end stop of the freq range.....so we woudl likely need to change the Cres so that we can achieve 12s...but then we may hit the overvoltage anyway.It woudl be good i mean, to be sure, we would need Lpri, Lsec Lres and Cres of the LLC converter , as well as the f(sw) when at max load on 10S, 5A...then we could simulate what youve got there.But yes, you are probably hitting Overvoltage with the 12S.
Want to use CAD to model complex multi-roof, solar array sun shine and shade. - Page 1
Forum section: electronics / general

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: October 23, 2022, 12:09:29 pm
content: I'm trying to help a friend who is embattled with solar quotes. He's got house with a terrible roof for solar in that it has hips and valleys everywhere which would require several separate banks of panels to achieve a significant output. The quotes are a bit inconsistent and we'd like to see a graphic representation of sunlight on, say, 4 different seasonal days.Shading isn't a consideration since house is two-story and the few trees that might cause problems can be pruned. But the house will rely on both a morning and afternoon facing arrangement.Looking for suggestions for websites or even a Linux program that could science this up a bit ourselves without necessarily turning the project into a PhD thesis.What do you think?

author: Ice-Tea
author_rank: Super Contributor
timestamp: October 23, 2022, 12:31:37 pm
content: 1) Sketchup allows for solar simulation I think?2) get optimizers. solves those issues.
Determination of SC and OC requirements when no SOA is available - Page 1
Forum section: electronics / general

author: insanoff
author_rank: Contributor
timestamp: October 16, 2022, 02:27:32 pm
content: Hello everyone!I want to build a single-phase DC/AC inverter based on STMicroelectronics PWD13F60 chip. Currently, I am considering how to design SC and OC protection. However, I am having difficulty determining the requirements.Below is the link to the datasheet. Unfortunately, the datasheet does not specify the SOA of the mosfets, but only some absolute maximum values at various temperatures. Although it mentions that the peak value is obtained based on SOA as well. But the actual diagram is nowhere to be found.I would like to know how in such a situation the requirements should be defined, for instance how long the mosfets can hold out at different currents. I can assume that the short circuit limit is around 1us. However, it is very difficult to define overcurrent conditions.Datasheet:https://www.st.com/resource/en/datasheet/pwd13f60.pdfProduct page:https://www.st.com/en/power-management/pwd13f60.html

author: Faringdon
author_rank: Super Contributor
timestamp: October 16, 2022, 04:01:37 pm
content: I dont believe any mosfet datasheet defines what you ask for.I think you have to use IGBTs, and just slow the switching frequency down to suit them.

author: jonpaul
author_rank: Super Contributor
timestamp: October 16, 2022, 04:14:50 pm
content: SOA was a spec from early BJT power transistors seldom used nowadays.:wtf:power FETS have different failure and dégradation mechanisms.read the IR, Siliconx and other power FET manufacturers app notes.Jon

author: insanoff
author_rank: Contributor
timestamp: October 16, 2022, 06:15:19 pm
content: Quote from: Faringdon on October 16, 2022, 04:01:37 pmBut the selected IC is what I really need. My requirement is only max. 1kW. For an IGBT I would also need a driver IC and much more technical knowledge.

author: insanoff
author_rank: Contributor
timestamp: October 16, 2022, 06:18:01 pm
content: Quote from: jonpaul on October 16, 2022, 04:14:50 pmI did not know it. I will try to find some application notes and study them.
How can i decrease initial acceleration on EV throttle ? - Page 1
Forum section: electronics / general

author: raamonkhan
author_rank: Newbie
timestamp: October 16, 2022, 06:44:02 am
content: Hi ,How can i change the acceleration on this throttle?Can i add a capacitor/resistor in order to decrease the quick acceleration when the throttle is barely touched. I want the bike to slowly creep a bit first before ramping up the speed . . it is difficult to manoeuvre the bike slowly when driving in confined spaces . . it jumps forward immediately even when the throttle is slowly twisted for a millimeter.The bike has a low and normal speed, but the initial acceleration on both speeds are the same . . .is there a way to restrict the initial voltage that goes from the 0-5V potentiometer (5k Ohm) ?Here is what the throttle and potentiometer looks like....attached.Thank you in advance !

author: Slh
author_rank: Regular Contributor
timestamp: October 16, 2022, 07:08:47 am
content: More details about the bike would be useful. What's the model? Do you have a wiring diagram for it? How about a manual?Does the throttle control torque or speed? Ie, if you hold the throttle at a fixed position does the speed change as you go up/down hills or does it stay the same?I've seen this sort of behaviour with motor controllers where they have a highish minimum duty cycle and fixed switching frequency. You get uncontrolled acceleration to say 5% of maximum speed. If that's the case then there's nothing that you can do about it.

author: raamonkhan
author_rank: Newbie
timestamp: October 16, 2022, 08:03:15 am
content: Hi Slh,It feels as if the speed stays the same if the the throttle is held in the same place , i cannot test it , as the tricycle is on a farm at the moment, in storage.We bought it brand new, to move compost and plants around in a garden on the farm, but it is very difficult to manoeuvre the tricycle slowly through small pathways and flower-beds as the slightest twist of the throttle shoots the tricycle quickly forward, although you then move at a slow speed.This is what i could find in the manual that came with the TailG Tricycle:It says in the manual hub-motor but it is a motor that is situated in the middle of the axle (equally far apart from the two rear-wheels, where the diff is, just an external electric motor that drives the axle shaft)Model:TL1500DZH-5ASee attached pics also.I hope this helps.

author: f4eru
author_rank: Super Contributor
timestamp: October 17, 2022, 07:06:01 pm
content: First thing to do would be to find out the brand/manufacturer of the motor controller.Often, they have a small configuration PC program you can download on their website (using google translate from Chineseand use to access and change parameters including acceleration/softness....
UCC28070 interleaved dual Boost PFC controller - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: October 14, 2022, 09:58:45 pm
content: Hi,In this thread, there is talk of problems with UCC28070...https://www.eevblog.com/forum/projects/bridgeless-pfc-controller/..post #5 mentions many people having trouble with UCC28070.Also, in this thread, an Engineer says he used UCC28070 with a Hall sensor instead of a CST.https://www.edaboard.com/threads/how-do-you-build-an-offline-isolated-multiphase-power-supply.309323/(Post #20)Also, the following thread in posts #3 and #6 suggests UCC28070 problems..https://www.eevblog.com/forum/projects/looking-for-a-pfc-preregulator-in-the-~1-5kw-range/Also, i had 2 of them blow up on me from ESD like damage.I actually think there is some issue with the use of the CST with the UCC28070, and that biasing resistors, and ramp circuits, (as in the app notes) are needed to "manage" the connection of the CST to the UCC28070 otherwise, problems can ensue.The thing is, the calculation of values for the biasing resistors is not given.Obviously they have got it right in their demo board, but thats for that specific case only.Without access to the ti.com forum myself..(you need a corporate email address to get on the texas forum) ..does anyone know of issues with the UCC28070?
From 1932: splicing a paper-insulated, lead-covered power cable - Page 1
Forum section: electronics / general

author: AlbertL
author_rank: Regular Contributor
timestamp: October 11, 2022, 02:04:48 pm
content: I wonder how many hours that process required:

author: Gyro
author_rank: Super Contributor
timestamp: October 11, 2022, 06:02:18 pm
content: I like the ladle to ladle tinning / soldering method. I bet that's harder than they make it look!

author: fourtytwo42
author_rank: Super Contributor
timestamp: October 11, 2022, 06:10:41 pm
content: This was still being done when I was a boy in the 50's, still completely hooked on the smell of molten pitchOr anything like it (Best Welsh steam coal comes to mind)

author: f4eru
author_rank: Super Contributor
timestamp: October 12, 2022, 09:38:59 pm
content: HV splicing ain't easy.today :

author: coppice
author_rank: Super Contributor
timestamp: October 12, 2022, 09:41:41 pm
content: Quote from: Gyro on October 11, 2022, 06:02:18 pmIts hard the first time, but once you get a little experience its pretty quick and easy.
Island inverter can be PWM or Phase-shift? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: October 02, 2022, 06:16:38 pm
content: Hi,We are doing an islanded inverter for use just with washing machines, fridges etc, possibly showers too......is it best to do it with PWM'ing...as in the attached LTspice....or Phase-Shift switching of each leg?Also, for a mains non-GT inverter, it looks like it'd best be done with SiC FETs, because you cannot avoid turning the top FET on when the bottom diode in the same leg is in full conduction...would you agree?...in fact, it makes you wonder how they did high frequency mains inverters before sic FETs were brought in?....maybe very low frequency and very staunched switching speeds?

author: dmills
author_rank: Super Contributor
timestamp: October 08, 2022, 12:38:53 pm
content: 'Modified sine wave' is what almost everyone did, to a greater or lesser extent.If you do it with say 3 rails or such you can actually get remarkably acceptable THD without any need for high speed switching on the output side.Granted, at 6+kW that may or may not be the sane approach...
Power bank recommendation  - Page 1
Forum section: electronics / general

author: james_s
author_rank: Super Contributor
timestamp: September 30, 2022, 05:05:32 am
content: I have a Iniu 20k mAh power bank that works well except for a serious flaw, I cannot find a way to disable the auto-power off at light/no load and this creates an annoying situation where my phone reaches fully charged and then buzzes as it detects the charger was disconnected, the buzzes again when the power bank detects something and turns back on. Anyone know of a specific model in this general size range? It's for a non-technical family member so I don't want to deal with hacks like plug in loads to defeat it.

author: Peabody
author_rank: Super Contributor
timestamp: September 30, 2022, 03:21:34 pm
content: You might look at the powerbanks made by Voltaic Systems. They are sold on Amazon. They specifically advertise as "always on". I don't know what sizes are available, but they are expensive as I recall.
UC3902 Load share controller needs more explanation? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 26, 2022, 06:32:06 pm
content: Hi,The UC3902 claims to be able to make independent SMPS’s load share when paralleled.However, the claim is somewhat contrived , as quite a lot of extra setup needs to go into it…..and things like external circuit trace resistance, maximum allowable sense resistor voltage, etc etc, are not explained out in the UC3902 datasheet or app notes. This is why so many UC3902 based load share circuits simply don’t work.The attached is an LTspice sim of whats needed to load share 3 linear regs….(SMPS sim takes too long).This is the way it must be done…not with UC3902 and no extras….with the sim you can verify the sense res and trace res.Is it time for UC3902 Apps docs to give the full picture needed to use it?UC3902 datasheet:https://www.ti.com/product/UC3902Note the sim has a ref voltage added to the sensed voltages, also has error amp vref window limiting....these are essential for the sharing, but not even explained in any of the UC3902 app notes.....if these factors are not tuned to the application...sharing doesnt happen....the UC3902 app notes fail to make this clear.
Using the EV to power the house. Peak/off peak energy price mitigation. Video. - Page 1
Forum section: electronics / general

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: September 22, 2022, 08:03:18 am
content: That's the idea. What do you think?

author: jonpaul
author_rank: Super Contributor
timestamp: September 22, 2022, 10:05:56 am
content: http://www.priups.com/

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: September 22, 2022, 10:10:51 am
content: Quote from: jonpaul on September 22, 2022, 10:05:56 amGood one.The fact that the site is written in HTML in this day and age gives all of us some hope.

author: f4eru
author_rank: Super Contributor
timestamp: September 26, 2022, 08:32:55 am
content: V2L : good for camping, or emergency power during a cutoff. Ford and Hyundai already have those. Please, OEMs, make sure this can be upgraded by SW to a synchronized system.V2H : simple paperwork (no feed-in into the grid) but complex on the regulation side, needs tight interaction between inverter and house power measurement device...non-interactive V2G : you profit from the battery directly, and feed-in when thee price of electricity is higher.Networked V2G : The Battery and charge management profits the grid operator (or VPP operator) -> That's the best combination to achieve on the long run, and technically simple, because the response time can be much slower, and it does not need any current measurement.There are two hardware flavors for all of those :- AC V2G/V2H -> costs <1k$- DC V2G/V2H -> costs >4k$The cost difference is so huge, because a DC based system has to install a dedicated inverter. An AC-based system uses the charger of the EV as a bidirectionnal inverter.Basically, all the startups doing DC-based V2G (often even based on the obsolete Chademo standard) are doomed to fail economically, because it just cannot scale over the level of early adopters.What we need is OEMs offering bidir chargers that could be synchronised to feed into the grid...No OEM has demonstrated that yet, and it's really a pity that Tesla does not push that...
Torroid cores for energy harvesting from the mains? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 28, 2022, 05:33:20 pm
content: Hi,Just noticed that digikey etc dont stock split powdered iron cores for clipping round house incoming line so that small amounts (~1W or so) of energy can be harvested from the mains.Do you know of any offtheshelf parts?Thes nano-crystalline cores are available but are not sold as "split".http://www.gaotune.com.hk/nanocrystalline-core/ring-core/nanocrystalline-current-transformer-core-17.html

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: September 28, 2022, 09:45:45 pm
content: Why would them?Also, as everybody knows, the amount of power you can extract depends on the load applied to the mains ring.What's the real problem that you are trying to solve?

author: Faringdon
author_rank: Super Contributor
timestamp: September 29, 2022, 09:13:46 am
content: its like in this device...https://youtu.be/7U9f4v1OAswIt gets all its power by harvesting from the mains.

author: jonpaul
author_rank: Super Contributor
timestamp: September 29, 2022, 10:28:47 am
content: "split toroid" is not stocked anywhere.Use UU or UI ferrite.Check Micrometals for Powdered ironJon
Boost PFC torroid inductor with more than one layer of windings? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 23, 2022, 07:12:06 pm
content: Hi,With Boost PFC's , using torroid inductors, would you say its normal practice to use a torroid (or torroid stack) that enables a single layer of turns to be used?...or is it common to have more than one layer of turns with such inductors?.....AYK, Proximity effect losses drastically increase as you use more than one layer of turns.

author: Wolfram
author_rank: Frequent Contributor
timestamp: September 23, 2022, 08:36:11 pm
content: Both are common. The RMS value of the ripple current fraction is usually an order of magnitude below the LF component, and the losses go with current squared. Even having a factor of ten higher AC resistance at Fsw compared to at 100 Hz, eddy current losses in the winding will only account for around a tenth of the total copper losses. The added copper of the second layer can often offset this, but whether it's worth the extra cost and hassle changes from case to case.

author: jonpaul
author_rank: Super Contributor
timestamp: September 23, 2022, 08:53:32 pm
content: Multilayer toroids increase shunt C and decrease SRF.more difficult to fabricant as Toroid winding machines must pass the shuttle through the center holeJon
Chinglish MPPT controller datasheet - Page 1
Forum section: electronics / general

author: pvc
author_rank: Newbie
timestamp: September 18, 2022, 07:45:16 pm
content: Hi! I am currently working on some diagnostic/control software for my MPPT solar charge controller. I am having difficulties deciphering whatever authors of this datasheet could possibly mean. Full document is availablehere. Parts marked in yellow are most troublesome. As non-native English nor Chinese speaker, it is quite confusing to me. Any help appreciated.

author: Vincent
author_rank: Regular Contributor
timestamp: September 19, 2022, 04:37:08 pm
content: The only one I'm fairly sure about is the last one. I believe D2D stands for "dusk-to-dawn".As for the rest... yikes.@D14, I assume 365 is one whole year?D12... percentage of rated voltage?Could D7 & D6 divide a certain period of time into respectively 6 and 5 equal parts?D3... maybe a timer that turns the load off after a fixed period?...my brain hurts now.
Check my reactance calculations - Page 1
Forum section: electronics / general

author: snoop33
author_rank: Contributor
timestamp: September 13, 2022, 05:20:42 pm
content: Head scratching this one. I'm counteracting the reactance of an inductor with capacitors and have computed the ideal capacitance and reactance delta which should lead the phase closest to zero.For human use, frequency is converted to kph.From the graph we can see the switch point is around the 17kph mark, that is, both sets of capacitors should perform about the same.In real-life it's way off, the switch point is 27kph.Coincidentally if I divide the inductance by half it's almost bang on at 26kph. Urm...Anything wrong with the calcs?

author: ahbushnell
author_rank: Frequent Contributor
timestamp: September 13, 2022, 11:17:23 pm
content: Quote from: snoop33 on September 13, 2022, 05:20:42 pmExcuse my ignorance. What is kph and which humans use that for frequency?Thanks for spinning me up.Andy

author: snoop33
author_rank: Contributor
timestamp: September 14, 2022, 07:36:00 am
content: Just ignore it.

author: Faringdon
author_rank: Super Contributor
timestamp: September 14, 2022, 10:33:27 pm
content: its just complex numbers.....if they are in series, then Z = jwL + 1/jwC = jwL - J/WcSo to get in phase you make the imag part zero.....so wL - 1/wC = 0

author: snoop33
author_rank: Contributor
timestamp: September 15, 2022, 02:34:50 pm
content: Sure, but that's not answering the question.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: September 16, 2022, 07:56:36 pm
content: Dumb question because I'm not completely familiar with your application.What's the real device and how did you measure the reactance at different speeds/frequencies?(about your factor of 2, w = pi*f, perhaps you missed one?)

author: snoop33
author_rank: Contributor
timestamp: September 17, 2022, 08:10:50 pm
content: The real device is a generator.I think you're asking how I know the calculated figures are wrong. Inductance is provided by the manufacturer. When the phase angle is closest to zero then LCR becomes R (ignoring some series resistance in the capacitors and inductor). By reducing R till MPPT is reached, when the two capacitance values give the same reading then that is the ideal frequency switch point (both phase angles are the same).The spreadsheet is attached, I can't see anything wrong with the calculations, so it remains a bewilderment.

author: snoop33
author_rank: Contributor
timestamp: September 18, 2022, 08:26:26 am
content: It's looking like they are correct, the issue is the inductance value supplied is incorrect.
Modifying battery in use on a day/night solar vent - Page 1
Forum section: electronics / general

author: SierraLima
author_rank: Newbie
timestamp: September 16, 2022, 03:18:44 am
content: Greetings everyone,So I live in a reasonably humid area and I own an enclosed trailer. The trailer has a Marinco N20804S solar vent w/ overnight battery (https://www.marinco.com/en/p/n20804s). I'm currently keeping it under covered parking when not in use which obviously means the fan on the solar vent isn’t circulating the air for long after I park it in the shade.I’m looking to modify it to be able to run for extended periods of time unattended as an addition to it’s normal capability. What I have in mind is to have a switch and an external battery plug that switches it from using it’s internal 2.5Ah 4.8V NiMh battery (https://www.marinco.com/en/p/n20890) and to be able to be powered by an external 20Ah (or more) 12V SLA battery. This large SLA battery will not be charged by the solar cells and I’ll charge it at home with a battery tender or something along those lines.According to the specs, the unit can run for about 24 hours on the internal 12Wh battery, so power draw is roughly 500mW. So with a much larger 240Wh battery it should run for about 20 days or almost 3 weeks. It’s a reasonable expectation I will tend to it every few weeks and recharge the large external battery so that should suit my needs.I thought about just using a much larger NiMh battery, but man are those things pricey. Even still I can’t find one with near that watt hour capacity at 4.8V so I’d realistically need to wire several large 4.8V NiMh batteries in parallel to get the endurance I need.I called the support people at Marinco and they wouldn’t divulge any technical details about the specs on the solar array, the fan motor or any of the electronics and they had no desire to help me modify the unit so I have very little to work with. I was initially thinking of maybe just connecting the SLA battery directly to the motor and circumventing the solar cells and charging/control circuitry but without knowing the specs of the motor, that doesn’t sound like a brilliant idea.Since I’m just a lowly software engineer and just an electronics hobbyist, I’m not 100% sure the implications of swapping not only battery chemistry but also voltage. So I figured regarding voltage, a simple 12V to 5V (close enough to 4.8V) DC transformer should do the trick. Since SLA and NiMh batteries don’t charge in the same way, my plan was to simply use a diode to ensure that even if there’s sunlight on the solar cells it can’t charge the SLA battery since the current can only flow one way, effectively eliminating this concern.Is there any reason this won’t work? Are there any factors I’m unaware of?Thanks,Omri
Using reverse recovery spike reduction inductor with PFC controller - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 14, 2022, 10:51:39 pm
content: Page 11, Fig 19, of the L4981 datasheet shows an reverse recovery spike reducer inductor (L2).If I use this circuit (which involves L2, D5, D6, D7, C14, R18) with the UCC28070A PFC controller instead, then do you agree, the L2 should go on the diode side of the Current sense transformer primary?L4981 datasheet:https://www.st.com/resource/en/datasheet/l4981.pdfUCC28070A datasheet:https://www.ti.com/lit/ds/symlink/ucc28070a.pdf?ts=1663195823926&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUCC28070A
SPD - Types and locations (consensus?) - Page 1
Forum section: electronics / general

author: 50ShadesOfDirt
author_rank: Regular Contributor
timestamp: October 29, 2022, 05:56:23 pm
content: Ignoring the source of my power (mains or solar), should I have a Type 2 at the load center/sub-panel(s) and Type 3's "in front" of (expensive) electronics? On the theory that SPD's are like "sponges", and more sponges would be better?From definitions I've found out there, Type 1 being the close-to-true "direct lightning strike" SPD, and Type 2 being the in- or near- the load center, and Type 3 being whatever made by whoever (SPD power strip, SPD block, etc.)Schneider Electric wants to sell Type 2's, but then with careful digging, they also have the blurb "recommend that you also have Type 3's". Thus, the sponge theory?On the Type 1, I'm assuming the absolute best protection is a well-built lightning rod and grounding system (buried ground rods/cables, trenching, etc. + lightning rods sticking up). Don't know how fast I could get to this ... but, can a true Type 1 be found and integrated?I think the Type 1 needs an "air-gap" system, to truly guard against a direct hit ... in addition to MOV's and whatnot.Will have a true ham shack one day, vs (not saying what I have right now) ... grounding would be very important here.Did I cover all the SPD needs?Comments?
Power supply "template" version needed due to component obselesence? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 09, 2022, 03:32:19 pm
content: Hi,When you get a consultancy to design a 2kW offline SMPS for you, do you get them to do an identical “template” version of it aswell? The “template” version is exactly the same components, but layed out in “open format”, so that all nodes can be easily probed. Also, the “template” is layed out such that all components can be easily removed and replaced….eg, transformer pins are not soldered in…the transformer is tied in with say fishing line, and the coils simply get terminated to PTHs in the PCB, so that they can be easily removed. Also, all FETs and diodes have there own easily removable heatsink, so they can be removed and replaced easily.Obviously, the “template” wont be any good for thermal testing, or EMC testing, but would be OK to say replace an obsolete component and check its basically OK at a first inspection.Any daughter boards are not put in sideways on, but are horizontal, (parallel to the main board) so that components can be easily probed on them….also, the daughter boards are easily remove/replaceable, since they are on PCB platforms, to which they solder just like a surface mount component. (the platform is soldered in to PTH’s on the main board.This “template” PSU is needed because any of the components may go obsolete/long-term-nil-stocked, and the consultancy is not likely to be instantly available to manage the replacement of the obsolete components.So do companies get such PSU “templates” made?

author: capt bullshot
author_rank: Super Contributor
timestamp: September 09, 2022, 06:07:36 pm
content: They'll make the "template" for you if you specify, order and pay accordingly, I guess.

author: fourfathom
author_rank: Super Contributor
timestamp: September 09, 2022, 06:21:49 pm
content: Sounds like a hack-job to me. Will you own the design and layout? If you aren't capable of developing the design initially, then how will you be able to make and test replacement parts and modules without the consultant looking over your shoulder? I can see modularizing certain sections of the design, but not as a separate test-breadboard.