hybridfree/eevblog-posts huggingface dataset:
Interleaved active clamp flyback converter - Page 1
Forum section: electronics / general

author: Dipak_rathod
author_rank: Newbie
timestamp: November 18, 2019, 12:49:38 pm
content: As per the figure we provides a dc voltage as a input to the interleaved active clamp flyback converter block, provide a PWM signal to the MOSFET which is in interleaved block for switching purpose. PWM signal is generated by the microcontroller which has a fix frequency 57 KHz and 50 % duty cycle then we got a output like triangular waveform. actually we will need a output like a given figure so which type of PWM output will be provided to the switching MOSFET, so we got proper output of the interleaved active clamp flyback converter.

author: f4eru
author_rank: Super Contributor
timestamp: November 18, 2019, 05:12:41 pm
content: typically, a flyback needs a feedback loop to give out a given voltage.Your output wave may not even be possible under some conditions.What is the application, load condition ? What are you trying to achieve ?A schematic of your converter may be useful.

author: MagicSmoker
author_rank: Super Contributor
timestamp: November 18, 2019, 06:00:10 pm
content: It looks like the goal is to generate a waveform that an H-bridge "unfolder" can make into 50Hz AC without requiring duty-cycle modulation of the H-bridge.But why an interleaved active clamp flyback was chosen is beyond me. Also, the contents of the OP is unintelligible.

author: Dipak_rathod
author_rank: Newbie
timestamp: November 19, 2019, 11:32:16 am
content: First of all thanks for your kind response.....Now,im providing feed back to the flyback circuit by means of input current and input voltage.the application of my circuit is to just boost low voltage dc to a high voltage dc for inverter type application.but the shape of high voltage dc is like a only positive half cycle of ac signal (like an pulsating dc output of a full wave bridge rectifier).as mention in the posted figure..now in my schematic of interleave flyback converter only two main prats is there first part is a switching mosfet and other is flyback transformer.and also i need pwm signal from controller as per figure..to switch mosfet very fast with 57 khz frequency and specific duty cycle...now this the all about my schematic description..schematic is also available at on line just search on google "active clamp interleave flyback converter."..now about load condition:load condition is pure resistiveor connected to the high voltage dc load/dc bulb..now pls answer how to get my desired output as shown in figure posted...

author: MagicSmoker
author_rank: Super Contributor
timestamp: November 19, 2019, 01:44:45 pm
content: Quote from: Dipak_rathod on November 19, 2019, 11:32:16 amYou need to generate a haversine* reference for the active clamp flyback converter's control IC. Please don't tell me you are going to control the active clamp flyback with a MCU - that is a recipe for disaster even if you have extensive experience with SMPS design.* - the correct name for a half- or full-wave-rectified sine wave.
Power Tool 120V lithium-ion battery packs - Page 1
Forum section: electronics / general

author: Weston
author_rank: Regular Contributor
timestamp: November 18, 2019, 09:28:53 am
content: I am working on a portable tesla coil (which I will hopefully be finishing and posting in the next month or so) that runs a boost converter to ~550V. Power draw is relatively modest at ~ 500W. I was originally planning on using a bunch of hobby li-poly battery packs in series to supply ~100V to the boost converter.As the project got closer to completion I discovered that 120V lithium-ion battery packs for power tools exist and are a pretty good deal. None of the larger companies use 120V battery packs, but Redback makes a 120V line of power tools. The chainsaw kit, which includes a chainsaw, 120V 2Ah battery, and charger, is $200 new and someone is selling them for $100 as unbranded refurbs on ebay. I recently bought one of the refurbs to check it out and use if for my project. $100 seems like a great deal for a 120V ~240Wh battery and charger. I figured this information could be useful for other peoples projects. This find influenced me to try to fit my tesla coil built into the chainsaw, with the coil replacing the bladeAs a summary of the teardown, the battery pack contains 30 high quality Samsung INR18650-20R cells (https://lygte-info.dk/review/batteries2012/Samsung%20INR18650-20R%202000mAh%20(Green)%20UK.html), which are designed for powertools and have a 2Ah capacity and a 22A max discharge current. The battery pack contains some sort of BMS that I have not identified. The only terminals broken out on the pack are the power terminals, a 12V tap which is only used by the charger (if anyone has a clue what this is used for that would be great), a single thermoresistor, and a pin labeled "ID" which measures as 10K ohms. The company sells a higher capacity battery pack so I suspect this pin is just a 10K resistor and used to identify the pack to the device, I had difficult tracing it on the PCB without having to disconnect cells.The refurbed chainsaw I bought arrived in barely used condition, except for a plastic grill which was crushed. The battery measured at 1.92Ah from a full charge to a cutout voltage of 3V per cell at a 1A discharge current. I have a second chainsaw kit arriving next week as it costs less than a single battery.For those interested, here is the website listing for the new chainsawhttps://redbackpowerusa.com/product/electric-chainsaw/and here is the ebay listing for the refurbed chainsawhttps://www.ebay.com/itm/Refurbished-UNBRANDED-120-Volt-Cordless-18-Inch-Chain-Saw-Kit/293255475559.18650 cells are ~ $3+ each in small quantities, so $100 for a 30 cell battery pack, chainsaw, and charger, seems like a great deal. My only complaint is that the battery pack seems to use a fuse instead of an electric cutout, but that is minor. I hope others can find these useful in their projects. Let me know if you need any more info. Here are some photos:Top:Side / BMS:
Domestic scale inverter tests under simulated grid problem conditions - Page 1
Forum section: electronics / general

author: TimSmall
author_rank: Newbie
timestamp: November 04, 2019, 10:05:08 am
content: I thought this was a fascinating video from UNSW (who are down the road from EEV HQ in Sydney and have a world class department for solar PV and related tech).https://youtu.be/k0N2LT5Vmng?t=68They've tested 10s of (standards compliant) domestic Solar PV Inverters by subjecting them to simulated electricity grid problems events (ranging from minor grid disruption up to serious failures which risk large scale blackouts), to see whether they end up helping the grid to ride out the problems, or make the situation more serious (e.g. by disconnecting and making the generation short fall worse).Shows how difficult writing good standards are...

author: TimSmall
author_rank: Newbie
timestamp: November 04, 2019, 10:13:58 am
content: ... Looking at some of their simulated failures, it made me wonder how a lot of cheap power supplies would handle a 90 degree phase angle shift in the mains AC waveform.I wonder how many cheap PSU designers even know this can actually happen?The sort of problems they're looking for is similar in some ways to the South Australia blackout - which was caused by a storm taking out transmission lines, and then amplified by software at severy wind farm which had been wrongly configured to disconnect too easily during multiple faults instead of "riding-through".The difference is that it's easy to change the settings at a handful of large sites, but a bit more tricky upgrading firmware on thousands of inverters in people's houses.

author: dmills
author_rank: Super Contributor
timestamp: November 04, 2019, 07:19:28 pm
content: I remember the Germans having an issue as well with solar that would not provide the reactive power needed to clear faults and instead just dropped off line?IIRC It resulted in some changes to the standards.Regards, Dan.

author: Phoenix
author_rank: Frequent Contributor
timestamp: November 13, 2019, 10:31:10 am
content: Quite an interesting presentation from John Fletcher. His comments that the ride through requirements of 4777.2:2015 are vague mirror my experience when implementing controls on an inverter to meet it. I'm not sure why the product would do on a phase jump or sag as we didn't have a good programming AC source (site tests didn't demonstrate any misbehaviour that could be attributed to these events). Inverters might be sensitive to these events because they use similar mechanisms to detect island events (e.g. dF/dt). Poorly designed control loops may also have some instability.However, for a different company/product I'm working on I need to meet other global standards too (E.g. UL1741 IEEE1547, VDE-AR-N 4105). Everyone has different requirements - need to make sure it can do them all. With the correct default settings and correct configurability.
How to test 3 phase RCD - Page 1
Forum section: electronics / general

author: Markusjames
author_rank: Newbie
timestamp: November 11, 2019, 06:06:59 am
content: How do I test 400v 3 phase RCD? I only have one phase source.

author: Jeroen3
author_rank: Super Contributor
timestamp: November 11, 2019, 01:30:28 pm
content: Apply nominal voltage to pins with test resistor. Press button.Check manual for which side you must feed. This matters with some brands!Note that nominal phase-neutral is most likely less then 400v
Inductive charging with interfering object in close proximity - Page 1
Forum section: electronics / general

author: roman.isaikin
author_rank: Contributor
timestamp: November 08, 2019, 10:02:54 am
content: Hi!I'm looking for a way to sanity check an idea of inductive energy transfer. The problem is, that in close proximity of the coils should be a PMSM motor and there is a concern that it would heat up. Of course there would be additional losses and this is acceptable if not destructive.Power required is around 50-100W, outer diameter of the coils = 100m, inner diameter = 85mm.Is there a way to estimate power losses in neodymium magnets, iron and aluminium or it would be easier to just build a prototype?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 09, 2019, 06:04:10 am
content: Why wouldn't you put a ferrite shield behind the coil? Greatly increases transfer efficiency too.Tim

author: roman.isaikin
author_rank: Contributor
timestamp: November 09, 2019, 07:02:36 am
content: Motor will be connected to a wheel, that would go through the coils, so on the top side I can't put anything. Not a problem for the bottom side though.

author: MagicSmoker
author_rank: Super Contributor
timestamp: November 09, 2019, 10:27:25 am
content: Anything conductive in the path of the magnetic field will heat up from eddy currents - this is the principle behind induction heating, after all - and any permanent magnet will heat up from hysteresis losses because of the wholepermanentthing (ie - difficult to magnetize and demagnetize).I'm having a difficult time imagining what you are trying to do here, though.

author: Marco
author_rank: Super Contributor
timestamp: November 09, 2019, 12:09:24 pm
content: Intuitively I'd worry about resonances building up in the motor wire more.That said, yes just build a prototype.

author: roman.isaikin
author_rank: Contributor
timestamp: November 09, 2019, 12:12:37 pm
content: It is a miniature robot with hub motor and a wheel that goes through the top coil (placed regular motor in the picture, since I don't have 3D model of a hub one). Bottom coil is the charge station.There is also a possibility to place two pair of coils side by side with the wheel, away from conductive materials, but they would be pretty small (15x40mm).Actually if the motor coils would be able to receive some of the energy, it would be interesting to modify an ESC firmware to allow battery charging.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: November 09, 2019, 04:14:19 pm
content: Quote from: MagicSmoker on November 09, 2019, 10:27:25 amBut ferrite has high resistivity. There would be some heating though. Ferrite is used in high frequency transformers.
Question on Phase Measurements in Socket Power Meters - Page 1
Forum section: electronics / general

author: DJB263
author_rank: Newbie
timestamp: November 08, 2019, 03:42:32 pm
content: Greetings People.After years of watching Dave and hearing about this superior blog i thought i would try to tap into the venerable wisdom of the EEVbloggers.Many socket power meters these days clame to measure power factor (PF), but i dont understand how this is possible without a CURRENT PROBE which most of them dont seem to contain.it seems to me that in most AC socket power meters, current is measured by measuring the very small VOLTAGE drop across a shunt of small resistance through which the main current flows. This voltage drop then goes through a ADC and into a processor, which because of the known resistance of the current shunt and measured voltage drop CALCULATES a current, which is then displayed.However, when a capacitive or inductive load is attached it will force the voltage and current out of phase, hence the current and voltage will be out of phase in the current shunt also !! making the calculation wrong.Am I wrong? Do socket power meters accuracy measure phase between V and I, if so, how?

author: KaneTW
author_rank: Frequent Contributor
timestamp: November 08, 2019, 03:48:24 pm
content: The voltage drop across the shunt is proportional strictly to the current going through it. The common mode voltage is (mostly) irrelevant.https://i.kane.cx/VYT6tNhttps://i.kane.cx/VoFK2B

author: edavid
author_rank: Super Contributor
timestamp: November 08, 2019, 04:45:59 pm
content: Quote from: DJB263 on November 08, 2019, 03:42:32 pmThat word doesn't mean what you think it meansQuoteAll true.QuoteDoes not follow.QuoteYes, you are wrong. The instantaneous voltage and current are measured at a high enough sample rate that VA, power, and therefore power factor can be calculated with reasonable accuracy.
Please Review my Custom Voltage Power Bank - Page 1
Forum section: electronics / general

author: lganimys
author_rank: Newbie
timestamp: November 03, 2019, 07:13:02 pm
content: Friends,I have developed this lithium-ion battery bank that can be custom set to any voltage under 12V. It can deliver up to 6 amps.Please review this and send your valuable comments and suggestions.https://youtu.be/xeFokAu-39kGanesh

author: BravoV
author_rank: Super Contributor
timestamp: November 03, 2019, 07:24:43 pm
content: Rather than viewing the lengthy video, why not you just explain in details in writing here ?Soldering directly at Li-Ion battery's tabs will ruin it and not recommended as it posed fire hazard.Regarding efficiency, just don't trust the claimed number from those buck-boost converter you bought from AliExpress.
2 pin Synchronous rectifier - Page 1
Forum section: electronics / general

author: va3nth
author_rank: Newbie
timestamp: November 02, 2019, 02:28:51 pm
content: Just watched a video from diodegonewild and he discussed a (new to me) 2 pin synchronous rectifier. Thought it might be of interest.https://youtu.be/FND4CKTwABUChristopher

author: JohnnyBerg
author_rank: Frequent Contributor
timestamp: November 02, 2019, 02:49:02 pm
content: $0.21 at LCSC:https://lcsc.com/products/Diodes-General-Purpose_370.html?q=45R20Is China the country where the innovations come from??

author: va3nth
author_rank: Newbie
timestamp: November 02, 2019, 07:12:58 pm
content: Thanks for the link! Would be interresting to try these out, especially at that price point.Christopher
TO-247 package rupture energy? - Page 1
Forum section: electronics / general

author: MagicSmoker
author_rank: Super Contributor
timestamp: October 28, 2019, 06:50:33 pm
content: Does anyone have even a ballpark estimate of this in Joules? For example, to select a fuse with the rather more modest goal of preventing the downstream devices from exploding when a failure occurs, rather than protecting them completely.I've found some discussion of this for IGBT modules, but nothing on plastic package devices so far hence the post here.

author: mzzj
author_rank: Super Contributor
timestamp: October 28, 2019, 07:08:12 pm
content: I can't say how many joules exactly but its not that much. TO247 is brittle package with no elasticity anywhere so it cracks really easily. But you can select how big bang you want.1 Joule won't do much, 10J probably pops the package open, 100J is starting to get interesting and 1kJ gets you in the big bang category.

author: MagicSmoker
author_rank: Super Contributor
timestamp: October 28, 2019, 07:37:17 pm
content: Quote from: mzzj on October 28, 2019, 07:08:12 pmHeh, point taken... I suppose I should rephrase that cracking and/or a little pop is okay (and probably unavoidable, as you point out) but an outright explosion followed by the device turning into a plasma blowtorch is not.

author: james_s
author_rank: Super Contributor
timestamp: October 28, 2019, 07:41:53 pm
content: Generally the bulk filter capacitance all but guarantees a spectacular failure in power switching applications. A fuse after the bulk filter adds stray inductance increasing the likelihood of a failure.

author: MagicSmoker
author_rank: Super Contributor
timestamp: October 28, 2019, 07:58:45 pm
content: Quote from: james_s on October 28, 2019, 07:41:53 pmThat very much depends on the amount of dc link capacitance. If using film capacitors with high ripple current ratings and for 3-phase inversion/active rectification very little capacitance will be needed, hence total Joules stored might very well be insufficient to cause explosive rupture (though a rupture of some sort, to be sure). I am more concerned here about the grid supplying the fault energy.
MCP73831 - Charge Termination Current Ratio (or percentage) - Page 1
Forum section: electronics / general

author: Stash230
author_rank: Newbie
timestamp: October 31, 2019, 11:19:45 am
content: On the MCP73831 Lipo charge IC there is an option for setting the Charge Termination Current percentage to either 7.5% or 20%. This is a ratio of the charge currenttermination value to the charge current setting (set by a resister). This value determines when, after Battery Voltage is reached, the charging terminates. Does anyone have insight as to why you would choose one percentage over the other? It would seem that a 20% termination would end charge sooner, but at what cost regarding charge? Is it better for the battery to cut off the charge at 20% vs 7.5% ? Couldn't find answer on Microchip forum or datasheets. Details: 10k resister for 100mA charge on a 200mAH 4.2v Lipo.Thanks,Laurence

author: Siwastaja
author_rank: Super Contributor
timestamp: October 31, 2019, 01:03:59 pm
content: Lower percentage gets you a tiny bit more charge in the cell,A somewhat "typical" cell might be 97% full at C/5, or 100% full at C/20 stopping (C/20 is usually the manufacturer datasheet specification and hence, defines what 100% means).Personally, I would choose the higher terminating current. The difference in stored charge is likely very small - so is the positive effect on the cell lifetime -, but it's nice to see the charging finish more quickly. Pushing the last few percent in at very low currents takes the longest, it's an asymptotic decay with diminishing returns.Note that this choice is good to have because you may not be charging the cell at very high rate to begin with. For example, if you are charging at C/10 normally, then you'd ideally configure the stopping current to be 50% of charging current (for C/20)!

author: Stash230
author_rank: Newbie
timestamp: October 31, 2019, 02:34:56 pm
content: Thanks! That was my thinking and I just needed a little extra "confidence". Really appreciate your time SiwastajaLaurence
Idea for power supply running PIC micro on Battery Voltage - Page 1
Forum section: electronics / general

author: vasonline
author_rank: Contributor
timestamp: October 21, 2019, 03:17:37 pm
content: Hi,I am designing a power supply for my PIC micro 16F series to connectto my inverter (documented by manufacturer)I wil use rs232 communication and a few led's for status.I have around 20-30mA max power consumption at 5VI have a 24V battery bank. (solar charged)I would like to run it of my battery bank.The Battery voltage can vary from 20V (on the low side) all the way to 32V (absorb).The LM317 can handle these voltages.But it's a big voltage drop for a linear regulator.Should I go for a buck converter or would (another) linear regulator more appropriate?I do like the simplicity of a linear regulator...Greetings and thanks!
Good use converter dpsVVAA : dps3005, dps5005, dps5015, and so. - Page 1
Forum section: electronics / general

author: myf
author_rank: Regular Contributor
timestamp: October 17, 2019, 03:39:00 pm
content: Hi everybody,I use a converter dps3005, and I don't know if it is resistant to connection errors.(1) Must I mount diode(s) or rectifier (with 4 diodes) before its input if one day I confuse (+)wire and (-)wire ?Its case has a very small second converter for the fan. Is it protected against the switching of the power cables or not ?(2) I connect the dps3005 to my power supply by a 5.5mm x 2.1 (or 2.5mm) plug. It is a cheap power supply, it looks like laptop power supply.It's a 36V x 3A = 108W power supply.When I connect converter and power together I get a light spark, and my dmm display a current peak at 20A or 30A (peak measure from a ut-61e), One instant after the current decreases at usual values 100mA or 1A.A 3A fuse remains and doesn't burn, this time is too short. Maybe 10^-2, 10^-3, 10^-4 second...Can my power supply will resist to this (very short time-very high value) current peak ?Must I decrease this peak in order to keep this power supply ? I don't know how... must I put a little resistor in serie on the input wire ?It looks like current peak when a motor starts.(3) If I use 2 power supplies AC/DC 40V for 2 dps converters, then can I plug them is serial or in parallel ?Is it better to place one diode on each (+) output in order to prevent the current from "going up" in the converter ?Can I even use this unit with a diode in order to refill battery (at the right tension) ? 14.1V for pb (car battery), 4.2V for one lithium cell ?(4) It seems that linux sigrok can read/write? data from/to new dps.Is there short programs in Python that can read/write theses dps devices ? (in order to plot Volt-Ampere caracteristics)(5) I may buy a usb-dps even if I already have one without usb link, for electronic tips and refill batteries.I don't know which model I must choice ?(i) low current=5A - high current=15A(ii) low tension=30V - high tension=50V(iii) decrease tension only dps - with decrease/increase tension dph(iv) laptop power supply in plastic case - led power supply in metal case(v) 36V or 48V power supply(vi) 3A - 10A - 20A power supplyThere is 32x3=96 choices !Thank you very much for your advices...F. from France
wvc 1200 - Page 1
Forum section: electronics / general

author: enti
author_rank: Newbie
timestamp: October 10, 2019, 02:52:29 pm
content: Hai,A new WVC inverter 1200 watts , after one day it died on me.No warranty!!Outside 40 degrees Celsius, input about 900 watt, and probably too hot.I think there are two resistors’ and one diode burnt out.Questions. Is there a way off finding out wat the value of the parts are.Is overheating the reason of the failure. And can there me more parts damaged.And wat is the function of the broken parts.And most important, can it be repaired?Thanks, I hope the pictures can explain more than I can tell.

author: f4eru
author_rank: Super Contributor
timestamp: October 13, 2019, 07:37:18 pm
content: Quote from: enti on October 10, 2019, 02:52:29 pmWhy no warranty ? any product sold in EU has the manufacturer, reseller and importer as responsible. (are you hte importer ?)Quote from: enti on October 10, 2019, 02:52:29 pmSure. This is a part of a H-bridge. locate the opposite supposedly identical section, and reverse engineer those.- RLC meter for passives.- Google "SMD cookbook" if refs are visible on semiconductors- cheap "transistortester" can often detect the type of componentQuote from: enti on October 10, 2019, 02:52:29 pmseems to be mosfet driver or current measurement stuff.Mosfets are probably blown too.Quote from: enti on October 10, 2019, 02:52:29 pmYes, but why ?it's often not economically interesting, and if badly designed will explode again.I recommend changing for a better brand when the chinesium stuff explodes after one day, and has no warranty.Quote from: enti on October 10, 2019, 02:52:29 pmYepPS: tu habites ou en France ?

author: enti
author_rank: Newbie
timestamp: October 13, 2019, 08:00:00 pm
content: Warrenty NO. I did buy the inveter in May this year from a seller in Eastern Europa, using Amazon, I tried to contact seller via Amazon but according to Amazon I never did buy the inverter in May of this year, so the did not want to help me further. Thats that!Anyway, thanks for the info up until now.One thing I don't understand is this answer"""Sure. This is a part of a H-bridge. locate the opposite supposedly identical section, and reverse engineer those.- RLC meter for passives.- Google "SMD cookbook" if refs are visible on semiconductors- cheap "transistortester" can often detect the type of component"""""Can you please explain to me (H-Brige ) what it means and where i can find the identical section?I'm not a electronic nurt, I try to understand stuff, but please keep it simple!!Living in France?Yes, unfortunately!!!Thanks

author: f4eru
author_rank: Super Contributor
timestamp: October 15, 2019, 07:52:10 pm
content: Ah, je suis en AlsaceFor the H-bridge, as you cayn google H-bridge, you'll see it's typically made by two identiccal half-bridges.So you have a similar/same circuit on the opposite leg presumably, and you can reverse engineer this one by measuring it's known good components
Solar cell encapsulation - is hermetic sealing required? - Page 1
Forum section: electronics / general

author: OwO
author_rank: Super Contributor
timestamp: October 08, 2019, 06:17:29 pm
content: I've seen solar panels used outdoors (on rental bikes) that are resin encapsulated instead of glass, and in theory these aren't hermetically sealed (all resins pass moisture through), so what is the general consensus on whether this is a good idea?

author: Marco
author_rank: Super Contributor
timestamp: October 08, 2019, 06:21:57 pm
content: 3M think they can achieve a25 year lifetimewith polymer ultra barrier film ... they are the experts.

author: ejeffrey
author_rank: Super Contributor
timestamp: October 10, 2019, 12:19:12 am
content: It also really depends on the type of solar cell. That 3M report is based on encapsulating thin film CIGS, CdTe, organic and dye based photovoltaics, the later of which are especially water sensitive. Crystalline silicon is, I believe, considerably less sensitive to water than any of those technologies.

author: splin
author_rank: Frequent Contributor
timestamp: October 11, 2019, 12:50:37 am
content: Quote from: OwO on October 08, 2019, 06:17:29 pmWhat do you suppose the average lifetime of a typical rental bike is before it's stolen, damaged or destroyed (or at least the more delicate accessories such as solar panels)?If you get more than 2 or 3 years out of a epoxy encapsulated panel you are doing OK but they can last a lot longer depending on their exposure to UV, temperature changes, rain, frost etc.

author: thm_w
author_rank: Super Contributor
timestamp: October 11, 2019, 01:15:46 am
content: Cheap resin panels are garbage. The surface is easy to scuff and collect dirt, and very hard to clean easily (think if leaves or sap will fall on them). Could last from as little as 2 years to 5 years.Big Clive had some good experience with adding a layer of rtv silicone on top of the cell but we are still talking ~1 year time span so far.
CO2 neutralizing shipments - calculator? - Page 1
Forum section: electronics / general

author: Martin F
author_rank: Regular Contributor
timestamp: September 24, 2019, 12:11:56 pm
content: Hi all,We're considering to "CO2 neutralize/compensate" all our order shipments as part of a set of sustainability initiatives.While we naturally realize that this doesn't make the CO2 emissions disappear, we figure it would be better than not doing any offsetting.However, I've looked for quite a while to find any framework/methodology/calculators to help set this up in a semi-formal way.Do any of you know of others that have done something similar - and how it's been set up?And do you know of any sources regarding how much the CO2 emission would be for a basic parcel (FedEx envelope) being shipped from X to Y and weighing Z kg?Thanks for your inputs,Martin
Current and future battery technologies? - Page 1
Forum section: electronics / general

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 16, 2019, 03:22:25 pm
content: How are things looking on the battery technologies front these days? It has been some years since I had a good look. Back then, graphene was looking promising, and there was some promise in molten salt batteries. Now I am also seeing hemp batteries being worked on. Maybe someone here has kept up with this stuff and can offer some thoughts on current battery technologies and where things might be headed in the future.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 20, 2019, 01:00:37 pm
content: No actually manufacturable "breakthrough" technologies in sight AFAIK. A lot of press releases, as always. But you never know. One of them might be up to something.Breakthrough likely not needed, though. Li-ion optimization (series of "small breakthroughs" and micro-optimizations) has not slowed down, and energy density has reached around 290Wh/kg, demonstrating approximately 40% increase per 10 years (1998 - 140Wh/kg; 2008 - 200 Wh/kg; 2018 - 280 Wh/kg). Usage of expensive active material is still going down, don't have exact numbers but price per capacity is clearly dropping a lot faster then the energy density is increasing.AFAIK silicon is now being successfully used in the anode (not alone, but together with graphite/carbon).Future? Based on what I have heard, it's fairly safe to assume the current development still goes on until about 350-400 Wh/kg. Halving the price per capacity seems possible. This is something that will happen during the next 10-15 years. IMHO, these expected numbers (Wh/kg and $/Wh) enable almost 100% electric mobility, because even with the current numbers, we are already pretty close. It might not be enough for 100% revolution in aircraft, though. I guesstimate somewhere over 500-600 Wh/kg would be preferred for that. For limited range aircraft commute, in busy central Europe for example, the li-ion technology we see in the next 10 years could be acceptable.Any real breakthrough is possible, and would be a massive extra boost, but it's extremely hard to know based on press releases. Most (99.99%) lead to nothing, and there is a lot of competition from investor money.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 21, 2019, 05:24:12 pm
content: Siwastaja, are you familiar with Robert Murray Smith and his youtube channel? Some pretty interesting stuff over there.

author: FreddieChopin
author_rank: Regular Contributor
timestamp: September 21, 2019, 05:51:03 pm
content: Li-Po batteries with graphene coated electrolyte offer a promise to improve capacity.
Sine wave power supply vs. stepped - Page 1
Forum section: electronics / general

author: tony3d
author_rank: Frequent Contributor
timestamp: September 15, 2019, 08:38:39 pm
content: Hi All,Just wondering your thoughts on this. I bought a new Jackery 160 Lithium power Station. It’s very high quality build, but I elected not to buy the pure sign wave version because I intended to use it just for my Dew Heaters on my telescope. Now I’d like to also power the drive motors. Since this produces a stepped sine wave would there be a possibility of wacky mount tracking, or worse damage to the drive system?

author: MagicSmoker
author_rank: Super Contributor
timestamp: September 16, 2019, 02:34:19 pm
content: Who knows... In fact, it is likely that even the telescope manufacturer can't advise you here.If the telescope relies on the AC mains frequency for sidereal tracking then your battery + inverter system should work fine, as the frequency will be divided down from a crystal oscillator and so will have almost negligible drift/error from 60Hz (or 50Hz, for that matter). The "modified sine" waveform is really just a square wave with a peak value the same as the AC mains (e.g. - ~160-170V for 120VAC RMS) but a duty cycle of less than 50% so it has the same RMS value. Some power supplies - and certain kinds of AC motors* - really dislike this bit of chicanery, but there's no good way to predict that unless you have considerably more detail than the pictures you posted.* - in particular, permanent split capacitor, induction and hysteresis motors really need to be supplied by a sinusoidal voltage

author: Seekonk
author_rank: Super Contributor
timestamp: September 16, 2019, 02:39:30 pm
content: I would suspect that many adjustable heater controls are phase angle SCR type. These would have problems with MSW. Or it just might not matter the exact temp as this is just to get mirror hotter than ambient.
solar … parkbench? - Page 1
Forum section: electronics / general

author: Lux49
author_rank: Newbie
timestamp: September 12, 2019, 11:03:46 am
content: Hey EEV-Blog friends, I just registered and this is my first post ever.So we are on vacation with our school right now, in Ireland. Yesterday we did a little trip to Howth near Dublin. And well, look what we found in the harbour area!Seems like a park bench with wireless charging! Well a friend of mine put his phone on it and … nothing. Sure it supports wireless charging but that parkbench seems to be broken.I find it so funny that people come up with funny ideas like this and even make it to a final product. Actually, I don't think this is as bad of an idea as solar roadways, if it would work, that is.That being said, if anybody wants to investigate this further, please do so. I just don't have the time for it right now but I still wanted to share this with you guys. I'm really curious to find out more about it!What are your opinions on this?Greetings from Dublin!Lucy

author: john61ct
author_rank: Regular Contributor
timestamp: September 12, 2019, 05:13:10 pm
content: PR stunt, past its use-by

author: Seekonk
author_rank: Super Contributor
timestamp: September 12, 2019, 07:44:40 pm
content: Where are the connectors? Those black things on the side? That seems like the fail point for something like this out in the weather.

author: ruffy91
author_rank: Regular Contributor
timestamp: September 12, 2019, 08:57:40 pm
content: No connectors, it uses Qi charging.

author: chris_leyson
author_rank: Super Contributor
timestamp: September 12, 2019, 09:31:12 pm
content: Thanks Lux49 for posting that, I've often wondered when QI would make a public appearance because it works well unlike dumb ultrasound or RF schemes, but there we are, linear thinking engineers understand the difference between near field and far field. I expect near field charging will appear in the not too distant future in a cafes, restaurants or pubs etc.Webpage is herehttps://www.include.eu/steora/makes sense to make it solar powered.

author: paulc
author_rank: Contributor
timestamp: September 13, 2019, 10:32:39 am
content: Great idea, needs to be implemented properly.(Solar cells will be FREE from useless solar roads and walkways)
Switching regulator problem  - Page 1
Forum section: electronics / general

author: catalyst
author_rank: Contributor
timestamp: September 10, 2019, 10:26:04 am
content: Hello,I have a design about switching regulator. It will be operated with 12/24Vdc supply. I have designed a circuit in the light of datasheet of AOZ1284PI.I have set the output voltage to 5Vdc.But I have some problems about design. When I use a resistive load whose current consumption is approximately 2Adc or 1Adc, there is no response or output from AOZ1284PI.Also there is no response or output from AOZ1284PI even if there is no load.If there is someone who will check my design, could you please help me? The schematic can bee seen at attachment.

author: thinkfat
author_rank: Unknown
timestamp: September 10, 2019, 10:53:45 am
content: What's L3/D3 supposed to do? The switcher may not like a high inductance at it's VIN.Also what's the voltage at the EN pin? Maybe R8 is a bit too large to actually have enough current flow through the 3.3V Zener?EDITed for more remarks:You're running it at 1MHz switching frequency, on purpose? 22µH is then maybe a bit high for the main coil, also, as you step down from 24V to 5V, the duty cycle is going to be small and the ripple current is going to be high. The SRP1038A-220M is rated at 5A. How much are you intending to pull from the regulator?Note that the regulator should still output 5V even if the components are maybe not optimal.

author: catalyst
author_rank: Contributor
timestamp: September 10, 2019, 07:09:03 pm
content: Yes, the main reason why I use D3 is protection for reverse polarity. Also, the reason why I use L3 is to suppress ripple currents. I have changed the inductor value with 4.7uH instead of 22uH. There is no change unfortunately.

author: DannyTheGhost
author_rank: Contributor
timestamp: September 10, 2019, 07:42:00 pm
content: As stated above by another message, issue might actually be in EN pin circuitryIn general, for zener you need calculate your resistor according to its 'stabilizing current' (haven't found more exact words for this term yet; how much current zener diode must sink to hold its breakdown state). Typically - it's 20-30mA, so 120k resistor would be suited only if you have 200V+ input voltage. Try with 1k resistor.

author: MagicSmoker
author_rank: Super Contributor
timestamp: September 10, 2019, 07:56:15 pm
content: R8 should be more like 10k, not 120k, and switching frequency should be more like 200kHz, not 1MHz. Otherwise it should work as-is.

author: thinkfat
author_rank: Unknown
timestamp: September 11, 2019, 01:05:58 pm
content: Quote from: catalyst on September 10, 2019, 07:09:03 pmYou can't suppress the ripple current. The switcher must be able to source those amps or it ain't gonna work
Phase Dimmer Control using Triac - Page 1
Forum section: electronics / general

author: dinesh4761
author_rank: Newbie
timestamp: August 29, 2019, 09:59:53 am
content: Hello Sir/Madam,I am engineering student making phase dimmer control using triacThe schematic is as attachedWhat I have observed that many times attached circuit stop working due to failure of triacI am not sure is it because of di/dt or dv/dt failure. In order to avoid this I have used triac of much higher rating (10A) even though current needed can be as low as 1A.However the problem continues.I have observed that the failure is for transformer powered halogen lamp (inductive load?) and for ceiling fans.It works satisfactorily for incandescent lamps.Also I am sharing one more observation that if I connect glass tube fuse link in series with the load then the fuse blows.From the various information available I realized that I need to use choke / inductor to overcome this problem. Is that right?I need help to1. To find out the value of the inductor for 0.5A, 1A and 2A2. Is this a special type of inductor? if yeswish to know makeThank you in advanceDinesh

author: Kartman
author_rank: Contributor
timestamp: August 29, 2019, 11:59:12 am
content: The choke (inductor) limits the rise of current which is highest at 90deg turn on. You want a core material that is lossy with high frequencies, like the Amidon yellow/white material. The actual inductance required depends on your current. Usually 200uH upwards. There’s plenty of info on the web to determine your inductance and selection of core size/wire size/current etc.Using phase control for motors is tricky - due to the inductance the current zero crossing is different to the voltage zero crossing so you need to adjust your on and off timing carefully.

author: Circlotron
author_rank: Super Contributor
timestamp: August 29, 2019, 12:07:26 pm
content: What could be happening is if the conduction time of positive and negative half cycle are not exactly equal there will be some DC current flowing in the load. With a transformer or motor load they can easily saturate with the DC and then pull a much larger than expected current. This imbalance will not affect an ordinary light globe.
Too Many Amps? - Page 1
Forum section: electronics / general

author: Rickyroller5
author_rank: Newbie
timestamp: August 23, 2019, 02:02:30 pm
content: I have a Lepai audio amplifier that requires a 5V, 2A DC input "wall-wart."Can I use a 5V, 3A unit without damaging the amplifier?

author: Kleinstein
author_rank: Super Contributor
timestamp: August 23, 2019, 05:09:05 pm
content: The input specs of appliances is usually the maximum current they use, or the minimum current the power supply should be able to deliver. So the power supply should be at least 2 A, a more powerful supply is not a problem. A 3 A supply is absolutely fine.I would just be careful if more than some 20 A, if there is no suitable fuse in the supply. It would not damage the amplifier, but a short at the cables from the supply could cause a mess.

author: David Hess
author_rank: Super Contributor
timestamp: August 23, 2019, 05:25:23 pm
content: Quote from: Rickyroller5 on August 23, 2019, 02:02:30 pmYes, the current rating represents the maximum available current but the load will only draw the necessary current.

author: john61ct
author_rank: Regular Contributor
timestamp: August 23, 2019, 09:57:05 pm
content: Yes, 300A or 3000A doesn't matter.More is fine, less is not.
Solar panels as a sun screen - Page 1
Forum section: electronics / general

author: nctnico
author_rank: Super Contributor
timestamp: August 21, 2019, 06:03:21 pm
content: I'm wondering about how effective solar panels are as a sun screen. Has anyone with solar panels on the roof noticed a significant improvement in keeping the heat out of the home after installing solar panels?

author: Seekonk
author_rank: Super Contributor
timestamp: August 21, 2019, 06:19:50 pm
content: Solar panels make great outdoor patio covers. The trend now is to have very close fitting panels to the roof for cosmetics with very little air space. Neither good for the house or solar production due to heating. It doesn't matter because most people in solar are morons.

author: bdunham7
author_rank: Super Contributor
timestamp: August 21, 2019, 07:31:12 pm
content: Quote from: nctnico on August 21, 2019, 06:03:21 pmI actually checked this after mine were installed because roof and attic heat is a big deal here. The inside of the roof stays cooler a little longer when the sun starts, but by noon I couldn't tell any difference and the attic was as hot as ever. So while I'm sure it helps, it didn't seem significant. My panels are about 6" off the roof. If there were 100% coverage and ventilation under the panels, I'm sure that would make a difference, but I only have about 15% of my roof covered in panels.

author: john61ct
author_rank: Regular Contributor
timestamp: August 21, 2019, 07:32:11 pm
content: The heat output radiated out the back of the panels from the PV process is enormous.Need an airgap so convection removes that radiated heat output, for PV efficiency as well as reducing heat gain into the roof space.Dunno about Tesla-style "tiles" though.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: August 22, 2019, 01:30:57 pm
content: Quote from: Seekonk on August 21, 2019, 06:19:50 pmYour comments made since except where did the last sentence come from?

author: Simon
author_rank: Unknown
timestamp: August 23, 2019, 07:42:28 am
content: My house was just as hot after installing panels and i have as much as i can have by law in coverage.

author: nctnico
author_rank: Super Contributor
timestamp: August 23, 2019, 09:13:13 am
content: Thanks everyone for replying and thinking along!Quote from: Simon on August 23, 2019, 07:42:28 amThat doesn't sound like a solution then. I can cover about 50% of my roof surface because of the various obstacles on the roof and the size of the (cheap second hand) panels I have found.
Cherokee Power Supply Info - Page 1
Forum section: electronics / general

author: deepskyridge
author_rank: Regular Contributor
timestamp: August 17, 2019, 09:55:55 pm
content: I have a new Cherokee Power Supply, Model QS3J1ABD I got from Ebay recently, it has 5v 75a and 2 12v outputs. It works fine.I am looking for a datasheet or connection info as this was not included in the box.I have attached a photo of one end of the supply, I am interested in the 5 pin connector in the top left, also the 12 position terminal strip.ThanksGary

author: john61ct
author_rank: Regular Contributor
timestamp: August 17, 2019, 11:11:18 pm
content: Got bought out by Lineage, which got bought by GE Energy, long time ago.With GE collapsing, I think now part of ABB?Cherokee was good stuff, had a CAR2548 for 48VMaybe google using the power specs rather than part number.Or just get someone to put it through its paces on a test bench?
Two PSUs in series equals double the power? - Page 1
Forum section: electronics / general

author: croto
author_rank: Newbie
timestamp: August 16, 2019, 09:18:20 am
content: Hi everyone, I'd like to know whether two power supplies connected in series will double the power capacity of my circuit, for instance:I need 48V ~500W, but I have two 24V PSUs that will deliver 250W each. If I connect the two together I will have my 48V, but I'm not sure I will have the capability of delivering 500W.Some of my colleagues and I had a discussion and I reckon it does. Double the voltage, same current = double the power.Thanks everyone.croto

author: Ice-Tea
author_rank: Super Contributor
timestamp: August 16, 2019, 09:31:14 am
content: Indeed. But both supplies would need to be isolated (so they don't share a reference) and have to support their maximum voltage to be 48V above earth/ground/whatever.Example: if you stack 2 600V PSU's they may only support up to 1000V with respect to their chasis.

author: croto
author_rank: Newbie
timestamp: August 16, 2019, 10:00:27 am
content: Thanks Ice-Tea

author: digsys
author_rank: Unknown
timestamp: August 16, 2019, 10:27:33 am
content: It does have its "cautions" though - they should be of the same type / power etc - and preferably have a ~28V type of crowbar on each, as they won't necessarily start-up / shut-down / react to faults etc exactly the same way. It is often done though.

author: f4eru
author_rank: Super Contributor
timestamp: August 16, 2019, 10:58:29 am
content: The PSUs need reverse protection diodes in paralell with them.

author: john61ct
author_rank: Regular Contributor
timestamp: August 16, 2019, 06:28:44 pm
content: Watts = Amps * VoltsAmps gets double in parallel, voltage remains.Volts get doubled in series, amps stays the same.Power is Watts, and that gets doubled in either case.

author: nctnico
author_rank: Super Contributor
timestamp: August 16, 2019, 06:44:03 pm
content: Quote from: f4eru on August 16, 2019, 10:58:29 amThere is no need for that. The internal secondary rectifier diodes will do the same (assuming it is a switching PSU which is likely given the power level).