hybridfree/eevblog-posts huggingface dataset:
Step Back Adjustable Output Converter - Controlled via Arduino - Page 1
Forum section: electronics / general

author: 2X
author_rank: Frequent Contributor
timestamp: April 14, 2021, 10:12:46 pm
content: Hello,I want to change the voltage of an output between 5V-12V (with max output currnet 7A). Does anyone knows if there is a chip switching regultor that has a pin where according the voltage that the arduino will set on this (or with a PWM - variable duty cycle) pin will change the output voltage? Every regulator that I find have the FB pin which has two resistors where the value of them will set the output voltage. One other solution it will be to create a back converter with a mosfet, inductor, capacitor and schottky but I saw that is not so simple. There is any calculator that will calculate what will be the values of the inductor and capacitor according the output voltage and current or because I don't want extreme precision on the output voltage and ripple there is any manual or site that will show how to select the right components with a "practical way"?

author: ledtester
author_rank: Super Contributor
timestamp: April 14, 2021, 11:14:15 pm
content: QuoteCheck out this page:https://www.fischl.de/dcdccontrol/
Dave bait: Debunking Microgym ? - Page 1
Forum section: electronics / general

author: PinheadBE
author_rank: Regular Contributor
timestamp: April 08, 2021, 10:18:08 am
content: What about this ?https://www.thegreenmicrogym.com/the-story-of-the-upcycle-eco-charger/

author: f4eru
author_rank: Super Contributor
timestamp: April 08, 2021, 07:13:51 pm
content: A bit expensive, but why notThey could have put the rectifier in a housing, and proper connectors on the cables.
What light bulb is this? - Page 1
Forum section: electronics / general

author: mvno_subscriber
author_rank: Regular Contributor
timestamp: March 23, 2021, 09:36:01 pm
content: First, sorry if this is in the wrong forum -- it was the closest my late evening brain could find.I discovered this light bulb lying in a crate of old vacuum tubes. It seems to say 110v 500W, which to me seems incredibly bright. Does anyone recognize this? What would it have been used for, and how was it made?My wife wants me to turn it into a lamp, it's quite pretty!

author: Bud
author_rank: Super Contributor
timestamp: March 23, 2021, 09:50:05 pm
content: This lamp will grant you a healthy electricity bill. Just saying

author: emece67
author_rank: Frequent Contributor
timestamp: March 23, 2021, 09:53:42 pm
content: .

author: Gyro
author_rank: Super Contributor
timestamp: March 23, 2021, 09:54:40 pm
content: It looks like a projector lamp - multiple filaments, closely spaced for good optical performance with a condenser lens.In a projector, it would have been fan cooled. Clean the glass before you use it - dirt and fingerprints cause localised heating.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 23, 2021, 10:01:44 pm
content: Looks like a projector bulb, similar tohttps://www.lightbulbs.com/product/ge-13355/?source=MicrosoftPPC-ProductAds&msclkid=eaa0cbd235b718634e2bab8851400881&utm_source=bing&utm_medium=cpc&utm_campaign=Product%20Listing%20Ads%20(LB)&utm_term=1100402329651&utm_content=All%20Products%20-%20Bid%20in%20Product%20Groups

author: daniel444
author_rank: Regular Contributor
timestamp: April 02, 2021, 06:01:11 am
content: try it on an old welding AC transformer they put out about 50v voltsyou can often find them discardedit should last longer on that voltage

author: tunk
author_rank: Super Contributor
timestamp: April 02, 2021, 10:11:13 am
content: And if you have a bench PSU, you could try 30Vdc.If it works and it's too bright, an 18-20V laptop PSU.
3-phase 380V from single phase 220V  (2kW bidirectional)  - Page 1
Forum section: electronics / general

author: Elmar
author_rank: Contributor
timestamp: April 01, 2021, 07:22:44 am
content: So I'm running a15kW bidirectional power supplyin a test setup that is running on 3 phase power.I'd like to be able to use this setup in places where I only have access to 230V single-phase outlets and don't have access to 3-phase power. I'd be ok with running it at lower power in this case, 2kW. I've talked with the supplier and they told me that the device definitely needs 3 phase power in order to operate, even if you use it at lower power ratings.So I'm looking for a 2kW bidirectional 220V 1-phase <--> 380V 3-phase converter, does anyone know if these exist?It's part of a setup that I'm mostly using for testing DC-DC converters where I'm supplying 2kW of power with the SM3300 power supply and then I'm sinking this power in the SM15K bidirectional power supply. Both of these devices can be connected to 3 phase power so I'm guessing I could also get away with a ~100W unidirectional 220V 1-phase --> 380V 3-phase converter but this feels tricky.I was wondering if anyone here has suggestions for me.

author: Nauris
author_rank: Regular Contributor
timestamp: April 01, 2021, 04:13:07 pm
content: I would first try quick solution with regular VFD fitted with output sine filter and brake resistor, step-up autotransformer on input and extra bus capacitor.

author: Berni
author_rank: Super Contributor
timestamp: April 01, 2021, 04:21:53 pm
content: The easy way is a rotary power converter.Take a 3 phase async motor, connect it to the 3 phases, connect the 220V single phase across two phases. Spin the motor by hand in one direction then plug it in. Once its gets up to speed turn on your gear. Works for bidirectional too.Slight improvemenr is to add a starting capacitor to the last phase so that the motor can start on its own, might also need a soft start resistor since it will pull a hefty amount of current on start up.
UPS 250L x 100Hx 90W max? 100 watts 240V - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: April 01, 2021, 01:17:17 am
content: Looking for a standby UPS that will fit in the above space. It has to go inside an existing piece of equipment. Anyone know of such a thing?

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 01, 2021, 02:13:19 am
content: Assuming those measurements are in mm, it shouldn't be too difficult to build a battery pack out of 18650s and have enough space left over for some power management circuits.

author: Circlotron
author_rank: Super Contributor
timestamp: April 01, 2021, 02:50:15 am
content: That's true, but I'd rather find something that is off the shelf. That approach also avoids me having to take responsibility for fire and electrical safety. Much better for some organisation that has all the relevant certifications. This is for 100-200 units per year.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 01, 2021, 04:17:36 am
content: If 12V will work, there are packs designed to connect in line with an existing 12V power supply.

author: Circlotron
author_rank: Super Contributor
timestamp: April 01, 2021, 07:15:28 am
content: Internally the system works on 30 V DC but will probably be okay with a bit lower than that. There is also a small supply that powers a control rail on the board so it’s messy to supply two different DC rails, one 24V or so and the other maybe 5 V. Easy to have one supply on the main side. Probably a DC to DC converter on the main side would be quite okay but I want to keep away from mains for voltage isolation issues. I’ve worked in the switch mode power supply industry the past and I know firsthand all the things you have to deal with to make it absolutely safe.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 01, 2021, 01:54:08 pm
content: 7S or 8S would be about perfect for 30V (7S a bit low at about 28V, 8S a bit high at 32V), then use buck converters for the 24V and 5V rails.
Brushed Generator output made safe for electronics? - Page 1
Forum section: electronics / general

author: vikisonline
author_rank: Contributor
timestamp: March 23, 2021, 09:23:17 pm
content: I have an 8kW brushed backup generator.It has a THD of 25% and I don't want to run my electronics on that.I got an Tripp Lite LC1800 which is a type of automatic transformer, and a 250W isolation transformer.I have tried using both. The chart below is the FFT of unfiltered generator output compared to output on the LC1800.There is a nice main peak at 60HZ vs the weird wide bar unfiltered.You can see the output is much nicer on the LC1800 but my UPS still refuses it. Same with my isolation transformer.Is there anything that can be done to further clean up the line, beyond going to dc and getting a sinewave inverter or buying anexpensive UPS that can handle generator outputs?Lastly I'm a sucker for not doing math by hand. Is there any open source/free software that can calculate THD from a csv waveform?
Current measuring on two buses - Page 1
Forum section: electronics / general

author: Eugenijus
author_rank: Newbie
timestamp: March 16, 2021, 07:29:06 am
content: HiIs it possible to measure the total current on two buses (using current transformers) together with one ammeter.The current is too high to use one bus , so two buses in parallel for the same phase .If possible- how to connect secondary windings of transformers ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 16, 2021, 02:57:46 pm
content: What would you want to display? The sum of both currents? What kind of sum, vector or RMS?If they are in parallel and presumably the currents are in phase and everything, why can't a bigger CT simply be used?CT secondaries can be wired in parallel, when the phasing and harmonics are the same. Use a smaller burden resistor, of course.Tim
Which offline flyback transformer is cheaper to produce?... - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: March 11, 2021, 06:40:22 pm
content: Which is more expensive and takes more production effort?...1..Flyback transformer with 2 layer primary….tape is put over the first primary layer, then 2nd layer over that tape, then secondary coil.2.. Flyback transformer with 2 layer primary, secondary is interleaved between the 2 primary layers.

author: f4eru
author_rank: Super Contributor
timestamp: March 11, 2021, 11:46:34 pm
content: The one that is produced in China is often cheaper.
Neutral Grounding of Isolation Transformer in Solar Energy system - Page 1
Forum section: electronics / general

author: quinton226
author_rank: Newbie
timestamp: March 04, 2021, 03:34:26 am
content: Hi every one! I am designing the solar energy system in Hong Kong.I shall follow the schematic from Power company to build up my system. But there is an question,"Why shall I need to have a neutral earthing at invertor side??What is the Advantage???"I find some answer in google with "NEUTRAL GROUNDING AND ITS ADVANTAGES" but I don't think it's the best answer, since there drawing is motioned in secondary side and for general transformer not specific for "Isolation Transformer". they are the follow:https://top10electrical.blogspot.com/2014/09/neutral-grounding-and-its-advantages.html(I) Voltages of the healthy phases do not exceed line to ground voltages i.e. they remain nearly constant.(II) Since the Fault Current will be higher and the MCB can be easy trip.do anyone know the Advantage of this?

author: f4eru
author_rank: Super Contributor
timestamp: March 04, 2021, 06:10:15 am
content: not having the complete system floating around, which would:- stress randomly the surge protections and various insulation- randomly fail panel insulation monitoring- in case of nearby lightning, induced voltage can destroy the system.....Do you need this insulation transformer at all ?Modern systems and most grids do not need this.

author: floobydust
author_rank: Super Contributor
timestamp: March 04, 2021, 06:53:29 am
content: OP, you double posted in Projects, I will move my reply here.The transformer neutral is grounded for electrical safety. The reason for this is if the transformer fails with a short-circuit between primary and secondary, there is a danger.If it was a distribution transformer, let's say for 11kV to 240VAC, a short in the transformer would try to connect the 11kV to the 240VAC side.With no secondary neutral connected to earth-ground, the secondary would float up to at most 11kV for the 240VAC output, which is very bad.Most distribution transformers are not 1:1 for voltage. The PV system is 380V but the building/switchyard might be 600V.Your paper says the "isolation transformer is recommended by Techical Guidelines". I'm not sure what it's for, other than keeping out any grid imbalance.

author: quinton226
author_rank: Newbie
timestamp: March 04, 2021, 07:30:32 am
content: Quote from: floobydust on March 04, 2021, 06:53:29 amTHANKS! this isolation transformer is 1:1 since in hong kong, all building must run in 380V system."isolation transformer is recommended by Techical Guidelines", i have read the guideline but talk less about this transformer.https://www.emsd.gov.hk/filemanager/en/content_299/TG_Grid_Connection_Renewable_Energy_Power_Systems.pdfthe Guidelines from Power company is more than this guideline. And i think the answer "The transformer neutral is grounded for electrical safety. The reason for this is if the transformer fails with a short-circuit between primary and secondary, there is a danger." is also a reason. THANKS!
1.5V AA & AAA  form factor: LiIon w/integrated regulator & NiZn - Page 1
Forum section: electronics / general

author: Howardlong
author_rank: Super Contributor
timestamp: February 17, 2021, 05:35:53 pm
content: Does anyone have any experience or comments about these cells which seem to be fairly commonly available online such as on Amazon?I've been using both in a handful of devices that suffer from intermittent current peaking (e.g, labelling machines with motors and hand controllers with force feedback or VR) and they seem reasonably OK.The drawback of the LiIon w/integrated regulator is that they stick solidly at 1.5V until the underlying LiIon drops to a certain level and then there's nothing, so battery gauges are useless. It may also be that different brands need different chargers.The NiZn has a higher native voltage (~1.65V) but does have a discharge curve, although it won't be fully compatible with a gas gauge designed for alkaline dry cells. These need compatible chargers, but chargers between brands should be compatible for cells with similar capacities. NiZn capacity and voltage is also very temperature dependent.Both are currently expensive, but possibly reasonable alternatives for when NiMh aren't compatible, and especially for devices which die when the current peaks on alkaline cells.

author: oPossum
author_rank: Super Contributor
timestamp: February 17, 2021, 05:52:47 pm
content: I have been using LiFePO4 (IFR) 14500 (AA size) cells as a replacement for AA alkaline. They are 3.2 volts so a dummy cell is required for each pair of cells. Can't be used with anything that takes an odd number of cells. Their capacity is quite a bit lower than NiCd, NiMH or alkaline partly due to the need for the dummy cells. Their ability to deliver current when required is very good. The flash for my camera charges up faster than it does with alkaline or NiMH. Flashlights shine brighter and more consistently. Overall I really like them despite the limitations.

author: ataradov
author_rank: Super Contributor
timestamp: February 17, 2021, 06:18:50 pm
content: Here is a recent review of a bunch of AA rechargeable batteries.
Solar Charge Controller - Connection Order - Page 1
Forum section: electronics / general

author: @rt
author_rank: Super Contributor
timestamp: February 09, 2021, 10:41:20 am
content: Hi,I thought this was the most appropriate area for my question. It’s a camper setup with PV panel, controller, and SLA battery.Almost every charge controller of this type on the market has the same connection order in it’s instructions, and marked on the unit itself.To connect:1) Plug the battery into the charge controller, 2) Plug the load into the charge controller, and 3) Plug the PV panel into the charge controller.Then this order is reversed to disconnect everything.I believe the reason for plugging the battery in first, is so the controller can initially read what voltage it is.I want to use loads such as lights that can be switched on and off, and other small devices that aren’t always on.Does anyone know why the load would have to be connected second in this sequence?The load output of the charge controller has over-current protection, and probably low voltage shutoff too,so although connecting loads directly to the battery seemingly solves the problem, it doesn’t really answer the question

author: richard.cs
author_rank: Super Contributor
timestamp: February 09, 2021, 11:05:09 am
content: I suspect the time timing of connecting the load is completely unimportant, what matters is ensuring the solar input is never connected without the battery already being present. Likely it can't keep the output voltage in a safe range without the battery there, so may be damaged or cause loads (if connected) to be damaged.
How long are Li-Ion batteries safe to use? - Page 1
Forum section: electronics / general

author: niino
author_rank: Contributor
timestamp: February 14, 2021, 12:13:11 pm
content: I have some very old Li-Ion battery packs from 2004-2007. They have been properly recharged every 6-12 months to avoid deep-discharge over the years, and still have enough capacity to be usable. However, I am worried about them aging over the years e.g. by slowly decomposing components - independent of other issues like deep-discharge and loss of capacity caused by many charging cycles. Is age itself a safety concern?

author: Siwastaja
author_rank: Super Contributor
timestamp: February 14, 2021, 12:45:39 pm
content: Of course, battery safety has made some improvements since 2004, and aging is a component in safety.If the device works with them properly showing decent capacity, there should be no significant concern.You can look it from the opposite angle as well; the fact the cells are still in good working order is a proof they are originally of high quality.By unnecessarily recharging the cells every 6-12 months based on beliefs originating from other battery chemistries, you have significantly compromised the cell life though. If the packs have survived despite that for over a decade, they are very good cells.Li-ion is best stored long term between about 20-50% state-of-charge and it does not self-discharge at that charge level, meaning it doesn't need maintenance charging.Badly designed battery management systems may discharge the packs though in which case some "management cycling" may act as a band aid to keep the cells non-overdischarged, and possibly balance them back from the imbalance caused by such improper management systems.The management systems have improved, some laptop packs from the 2005-2010 era are really bad, basically they just self-destruct even though the cells would be just fine without the faulty BMS.Look for bulging, excessive heating, voltage drop under load, low capacity and similar warning signs.

author: madires
author_rank: Super Contributor
timestamp: February 14, 2021, 12:48:53 pm
content: For long term storage charge Li-ion batteries to about 50%. More athttps://batteryguy.com/kb/knowledge-base/how-to-store-lithium-based-batteriesorhttps://batteryuniversity.com/learn/article/how_to_store_batteries.
Feedback loop calculation for monolothic control based Buck? - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: January 28, 2021, 07:05:42 am
content: Hi,This is a question no one can seemedly answer..We are trying to calculate the open loop small signal feedback loop transfer function for an LT3680 based buck converter.As you know, this is given by the [Power stage transfer function] x [Error amp transfer function] x [Modulator transfer function].The Equation 2A-5 in the attached gives the [power stage & modulator transfer function]. However, it contains the term “R/Ri”.How can we find out what Ri is for the LT3680?(Ri is the FET source sense resistor; R is the load)LT3680https://www.analog.com/media/en/technical-documentation/data-sheets/lt3680.pdf

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: January 28, 2021, 08:12:14 pm
content: I only gave a quick look at the application note you attached , so I probably missed something.Where's that equation, I couldn't find it?The internal blocks all have their transconductances defined, isn't that sufficient to derive what you need? (albeit with different units)

author: Terry Bites
author_rank: Super Contributor
timestamp: January 29, 2021, 04:14:48 pm
content: I cant see what eqn. you are referring to in this datasheet.

author: ocset
author_rank: Super Contributor
timestamp: January 30, 2021, 10:54:43 am
content: The equation 2A-5 is in the pdf attachment called "227". (top post)QuoteUnfortunately not, the transconductance parameter called "current mode power stage" comprises the modulator and power stage. However, they dont say what inductor value was used for this (or what output cap value). So it cannot be used to calculate the "open loop small signal transfer function" of the Buck converter

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: January 31, 2021, 06:55:55 pm
content: Ah my bad, I didn't see the attachment, only the link to the application note.Can you post more of that book chapter so we can try to follow along the derivation of that expression?
Low Voltage Buck controllers which provide "hiccup" style output s/c protection? - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: January 23, 2021, 02:31:09 pm
content: Hi,We need to do a Buck for 12V to 5V at 3A load.We also need output short circuit protection.Do you know why no offtheshelf chips (for Buck) exist which provide “hiccup” style short circuit protection as in the attached? (we had to use an extra discrete circuit here with a 555 timer)The hiccupping reduces the power dissipated in the diode when output is short.(LTspice sim and pdf schem attached)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 23, 2021, 05:33:02 pm
content: I've used several that do... often to my consternation. Which ones have you tried, that don't?Edit: on the LT3995 specifically, it doesn't look like it has it, but it might be easy enough to wire around the PG and SS pins. It also performs current and frequency foldback at low V(FB). Probably there is a sister product with the same design with a hiccup fault function.Tim

author: ocset
author_rank: Super Contributor
timestamp: January 23, 2021, 06:29:50 pm
content: Thanks, ive checked out all analog.com low voltage buck controllers, and none have hiccup mode.I dont think such exists in any company.As you know, AC/DC PWM controllers almost all have it..outside that , it is really rare...im checking through Renesas and ti.com etc, but no joy yet.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 24, 2021, 07:38:54 am
content: I think the problem is in nomenclature, and poor searchability of switch mode control ICs.I'm quite sure a significant part of buck ICs do what you want, but I'm not sure how to easily find them, either.I would go through all ICs (sorted by price or availability, for example) and look at each datasheetcarefullyuntil I find one which does what I want. Yes, this is slow, it often takes a full day of work to find the IC that does X while satisfying all other requirements you have.I think I have had the opposite requirement, needing to find a buck IC thatdoes notgo into either hickup or latched failure mode, just output roughly controllable constant current, and boy it was difficult to search.

author: ocset
author_rank: Super Contributor
timestamp: January 24, 2021, 05:45:16 pm
content: Thanks yes, even harder is to find a dcdc power module which fits your requirements...egOurs is as followsSMPSVin = 9-20VVout = 5VIout = 3AOutput must be short circuit protected.Output must be clamped to 3A (or go into hiccup if it goes >3A)
We need NiZn ferrite common mode choke but cannot find it? - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: February 07, 2021, 11:08:14 am
content: Hi,We have a radiated emissions problem at 80-200MHz.Therefore , we need to use a common mode choke rated for those frequencies in the output of our SMPS.This means it must be made of NiZn.But the offtheshelf common mode chokes dont specify what ferrite they are made of.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 07, 2021, 01:26:52 pm
content: For the high frequencies one may get away with 2 seprate inductors / ferrite beads: the high frequency material has low µ and is thus not so prone to saturation. The coupling is kind of needed to avoid saturation with the relatively high inductance to filter out the lower frequencies.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 07, 2021, 05:28:10 pm
content: have you triedhttps://www.coilcraft.com/en-us/tools/common-mode-choke-finder/#/searchWhy does it have to be this particular ferrite?What current does it need to carry?

author: iMo
author_rank: Super Contributor
timestamp: February 07, 2021, 06:33:00 pm
content: Ferrite NiZn material 43 works till 250MHz as EMI suppressor. Cheap as well.

author: dmills
author_rank: Super Contributor
timestamp: February 07, 2021, 06:50:12 pm
content: Yep, a 43 mix ferrite is very standard for small RF transformers in the HF and low VHF region, should be fine for this.

author: mairo
author_rank: Unknown
timestamp: February 08, 2021, 11:23:47 pm
content: Wurth Electronics has lost of varieties, even NiZn. I have theirs kits which help alot during 'difficult' pre-complience work.https://www.we-online.com/catalog/en/WE-CMB-NIZN
Witch lipo charger to choose? - Page 1
Forum section: electronics / general

author: ElectricPower
author_rank: Frequent Contributor
timestamp: January 19, 2021, 09:52:16 am
content: I want an good and powerful lipo charger that can charge at least 3S. More is better, but 3S is minimum. I know it is many out there to choose from.I have looked at folowing chargers, but i do not know witch to choose:- ISDT P30- HTRC T240 Duo- Sky RC B6I want an good and safe charger for an beginner. Easy to use etc. Price is not an big issue, but i do not want to buy the moon og course

author: ElectricPower
author_rank: Frequent Contributor
timestamp: January 20, 2021, 12:36:57 pm
content: No one?

author: HB9EVI
author_rank: Frequent Contributor
timestamp: January 20, 2021, 07:02:37 pm
content: For years I'm using the iMAX B6 Charger, which is equal to your Sky RC B6.So far I had to replace once a small power FET (IRF7811) otherwise it runs flawlessly.I'm also using it for NiMh and Pb batteries, everything works fine with it

author: faraday
author_rank: Regular Contributor
timestamp: January 20, 2021, 08:58:52 pm
content: Me too iMAX B6. Does not have noisy fan like most other chargers.
PFC sometimes doesnt make sense for offline power supplies? - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: January 17, 2021, 10:49:30 pm
content: If an offline power supply is drawing 2W of power virtually all the time, then why does it need PFC?I am working in a project consultancy doing work with an electronics contractor, ultimately for a big customer.The consultancy is making an offline 240VAC SMPS which after being installed, will firstly charge up a 24V battery at 5A for 3 hours. Then it will simply sit there for the next 10 years drawing about 2W of standby power, as the equipment continuously monitors some safety valves which should be actuated in case of emergency. The 24V battery also needs to be kept topped up with a “float” charge, but this is only part of the 2W standby power.As such, is there some clause in the EN61000-3-2 standard which we can invoke in order for us to avoid using a PFC stage?I mean, our average power draw is so low that surely a PFC stage would not be mandated for this?A PFC stage, for 3 hours of useage above 75W in 10 years doesnt make sense?Surely some clause in the regs exists saying that a simple offline SMPS can be used here?....ie no PFC front end?

author: f4eru
author_rank: Super Contributor
timestamp: January 18, 2021, 06:28:03 am
content: There are some exceptions.You'll have to find out if one of those applies to your product, but ultimately, if you need to sell it in EU(or many other countries), you often have to.One simple thing to do with a charger, is to modulate the charging current in phase with the 100Hz.Another solution is to reduce charging current to stay just under 70W
low voltage(3.7v) high current(135A) short circuit protection - Page 1
Forum section: electronics / general

author: benyB
author_rank: Newbie
timestamp: January 10, 2021, 03:14:42 am
content: I am making multiple 8 x parallel(lithium iron 18650 3.7v 3400mA) battery packs that should be under 100Wh capacity.The individual cells are not protected for over current. there for my ebike.Each x8 cell pack will need some kind of short circuit protection >100A , 135A ( 500w )The x8 cell pack has no BMS.I don't need charge voltage protection as the x8 cell packs will be connected together in series to make one large 36v battery that will have a BMS.I'm trying to design a modular battery that is designed to come apart.I need some protection against the small packs shorting out and going into thermal runaway ( catching fire ) !Should i used an existing battery protection IC and a few mosfets to increase the power ?It seams battery protection IC's monitor mV drop rather than detect current with with a shunt?I could calculate volt drop of a 500W draw on my 8xbattery pack and set the IC to trigger enough mosfets to switch off for 3.7v 500W maybe ?But I get a feeling this is way over complicated?If possible I want to avoid having a full BMS in each battery (they are just 1 large 3.7v cell ) and another BMS to control the 10 batteries hooked up in series !can anyone point me to a design that could achieve the low voltage high current protection ?How about a massive thermistor? is that even slightly safe?Its for an E-bike that can draw up to 500W peek

author: f4eru
author_rank: Super Contributor
timestamp: January 12, 2021, 08:37:13 am
content: strange inefficient design.Why ?

author: Siwastaja
author_rank: Super Contributor
timestamp: January 12, 2021, 09:15:50 am
content: By Kirchoff laws, same current flows through all cells in series. If you cut the path anywhere, no current can flow. As a consequence, current measurement and overcurrent (including short circuit) protection is done once, on the pack level.Possibility of current taking alternative routes is prevented by good mechanical design.If you try to come up with a design where each series element is separately protected "for modularity", the cost and complexity will blow through all roofs. Such protection needs to handle the full pack voltage, after all, so single-cell integrated solutions won't work. Just don't do it.

author: f4eru
author_rank: Super Contributor
timestamp: January 12, 2021, 07:53:58 pm
content: and also a lot of connectors at low voltage and high current in the path without reason is wasterful from both financial and ohmic losses points of view
Battery capacity tester which can dump energy into another battery - Page 1
Forum section: electronics / general

author: Freesurfer
author_rank: Regular Contributor
timestamp: January 09, 2021, 03:38:31 pm
content: I have a bunch of used lead acid batteries that are of the same model/capacity rating, but they have been pulled from different environments so some variation is to be expected. I have arranged them in several series strings, and then paralleled these strings for extra capacity.The problem is that when putting these batteries in series, the weakest battery in that string determines how much power I can consume from that string. For example one string when discharged may have 11.8 - 11.8 - 9.00 - 11.8V.When charging, it may be the other way around - 13.8 - 13.8 - 14.9 - 13.8V. Obviously the one battery is in worse shape than the others. But trying and failing is very time consuming so I'd rather fully charge all the batteries, run a test and then arrange them into the setup accordingly.But since I do not have mains here and need to charge from a generator, it would be nice with a battery capacity tester that would dump its discharged capacity, into another battery instead. I have seen such testers demonstrated on youtube before but can't find any appropriate one. It would be nice if it is a somewhat beefy tester. The batteries are 12V/86Ah

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 09, 2021, 06:18:44 pm
content: A boost converter module that supports current limiting will do what you're looking for.

author: capt bullshot
author_rank: Super Contributor
timestamp: January 09, 2021, 06:26:36 pm
content: You might check these battery chargers used for model aircrafts / cars / boats. Many of them are intended to be supplied by a standard car battery. Usually they support all common battery types. Most of them should have options for charging lead-acid batteries, most of them should have a "discharge battery" function and some might have the ability to dump the discharged energy into their input (if a lead-acid battery is connected), especially if they offer high discharge currents.
What defines a 'N70 size' battery?  - Page 1
Forum section: electronics / general

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: January 10, 2021, 04:34:03 am
content: I was looking at this..https://www.projecta.com.au/power-management-products/12v-portable-power-station-suits-n70-batterySearched around and I can find lots of things that house a 'N70' battery and many batteries that claim to be 'N70' in size, but I cannot find an actual specification for N70.Closest hint found was an Alibaba ad which has 70Ah mentioned.https://fjdouble.en.alibaba.com/product/1354453264-213715563/N70_12v_car_battery_specifications.html

author: beanflying
author_rank: Super Contributor
timestamp: January 10, 2021, 04:44:45 am
content: In Oz it is sort of the old defacto Landcruiser sized battery either an N70 or the slightly more gutsy N70Z. It is a more a dimensional or physical size thing than a CCA or Capacity thing.https://www.batteryworld.com.au/N70T-Yuasa-Deep-Cycle-Batteryhttps://www.batteryworld.com.au/N70ZZB-MF-Power-Glide-Maintenance-Free-Battery
Full Bridge driver datasheet showing incorrect synchronous rectifier drive? - Page 1
Forum section: electronics / general

author: opampsmoker
author_rank: Regular Contributor
timestamp: January 03, 2021, 06:03:24 pm
content: Hi, would you agree that the drive waveforms for the lower bridge fets and the synchronous fets on page 15 and 16 of the ISL6752 datasheet are mostly totally incorrect?....Fig 19 is actually correct, but its on a “knife edge”, there being no delay between switching of the lower bridge fets and synch fets. But its “basically” correct, since each synch fet is on for its relevant bridge fet’s on-time, and also for the “freewheel” time.Fig 20 and Fig 21 show each synchronous fet being ON when either left or right side lower bridge fets are on, and this is incorrect.ISL6752 datasheet:https://www.renesas.com/eu/zh/document/dst/isl6752-datasheet
Buck inductor V vs I - Page 1
Forum section: electronics / general

author: mikeinfodoc
author_rank: Regular Contributor
timestamp: December 26, 2020, 06:21:24 pm
content: I have seen this formula for Buck circuitwhile switch is on and inductor current is increasingVL=L * diL/dtIs there a similar simple formula for when switch is off and inductor current is DEcreasing?

author: ahbushnell
author_rank: Frequent Contributor
timestamp: December 26, 2020, 06:37:05 pm
content: Quote from: mikeinfodoc on December 26, 2020, 06:21:24 pmYour formula works for both cases. VLis the voltage on the inductor. When the switch is on the voltage on the inductor is Vin-Vout, When the switch is off the voltage on the inductor is -Vout.

author: opampsmoker
author_rank: Regular Contributor
timestamp: December 26, 2020, 09:16:59 pm
content: and here is free LTspice sim of buck for you so you can see it all happeningLTspice is free

author: Siwastaja
author_rank: Super Contributor
timestamp: December 31, 2020, 01:15:44 pm
content: It's not a formula for "buck circuit", it's an universal formula whichdefinesthe correspondence of time, inductance, current, and voltage. Hence, it is always true. You can use it to analyse any switch-mode topology, or any circuit containing inductance.For analysis, I recommend you re-draw the circuit schematic twice: separately for the main switch on and off states, drawing the switch and the diode either on (straight line) or off (gap), making it easy for you to label the voltages at nodes, and draw the path the current flows. Then apply the formula.
Will NFETs stay OFF when they  are not driven OFF? - Page 1
Forum section: electronics / general

author: opampsmoker
author_rank: Regular Contributor
timestamp: December 08, 2020, 11:28:06 pm
content: Hi,In the attached Back-to-back NFET circuit, the NFETs are initially turned off by the minus 3v source…but then the switch opens and the gates are just left floating. Will the NFETs stay OFF?....or is there a chance that background electromagnetic fields could induce them to come ON?LTspice sim and PDF schem attached

author: oPossum
author_rank: Super Contributor
timestamp: December 08, 2020, 11:34:58 pm
content: YesNoMaybePut a resistor between gate & source to keep them off.

author: David Hess
author_rank: Super Contributor
timestamp: December 09, 2020, 05:04:21 pm
content: Quote from: opampsmoker on December 08, 2020, 11:28:06 pmInternal and external leakage may gradually charge or discharge the gate voltage turning the FETs on or off.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 09, 2020, 06:08:00 pm
content: Theywilleasily float to interesting levels.It's an absolute must to drive it. Drive impedance should be far less than the leakages combined. A few hundred kOhm pulldown will almost always work.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: January 03, 2021, 02:43:15 pm
content: Fun experiment:Take a breadboard, a MOSfet to switch some load (simplest: LED with resistor) and add a (mostly for protection) resistor (1M or so) to the gate.Then touch the 1M resistor with one hand, and with the other hand alternatively touch GND and the power rails of the breadboard.

author: opampsmoker
author_rank: Regular Contributor
timestamp: January 03, 2021, 03:29:12 pm
content: QuoteThanks, ill do this when i get back to the workshop.I presume the FET turns on and off when either the rail or gnd is touched. (and thus the led goes on/off)What i hope is that when i touch the rail to turn the fet on.......then take finger off the rail, then hopefully the fet stays on for a long time.{EDIT: ie, because the fet's gate to source leakage current will (hopefully) be very very low, such that the undriven fet stays on for a long time}And hopefully this will be the case when the SISS40DN FET is used.{EDIT: Ditto the case for the fet being in the un-driven OFF state....ie, hopefully it stays off, and doesnt get induced on by anything in the atmosphere, other than the charged finger touching its gate again}EDIT: In the target application, there will not be any pull down resistors allowed.

author: janoc
author_rank: Super Contributor
timestamp: January 03, 2021, 04:14:47 pm
content: Hum, wasn't this dude designing switching power supplies for lighting before? This is a sort of question a newbie would ask ...

author: BravoV
author_rank: Super Contributor
timestamp: January 03, 2021, 04:17:13 pm
content: Quote from: janoc on January 03, 2021, 04:14:47 pmYep, seems like he sort lost in the thing called "pull down" in mosfet's ABC lesson for noob, while whining how to beat China switching power supply industries.
How do you  calculate  the inductor value in a HiperPFS-3 Boost PFC design? - Page 1
Forum section: electronics / general

author: opampsmoker
author_rank: Regular Contributor
timestamp: December 28, 2020, 01:25:32 am
content: Hi,Suppose you are doing a Boost PFC for 205-250VAC input, 400V output and 250W power.Then the way to find the inductor value is to get the switching frequency. Then you design a Boost converter for the Static case of Vin = 205*sqrt(2), and Vout = 400V and Pout = 2*250W. Using the equation Vout/Vin = 1/(1-D) , amongst others, one then assess’s what inductor value gives you the tolerated level of inductor ripple current. Thus you get your inductor value.….However, one cannot do this with the HiperPFS-3 controller, because you have no way of knowing what the switching frequency will be.There is a graph on page 7 of the HiperPFS-3 datasheet (Fig9a) which shows switching frequency at mains peak for various mains input voltages….but it does not give switching frequency for 205VAC. Also, Fig9a must only be relevant for a particular value of Vout, but fig9a does not say what this vout value is.So how do you calculate the needed Boost PFC inductance value for HiperPFS-3?HiperPFS-3 Boost PFC controller datasheet:https://ac-dc.power.com/sites/default/files/product-docs/hiperpfs-3_family_datasheet.pdf
Using lower DC voltage in the sets - Page 1
Forum section: electronics / general

author: vinlove
author_rank: Frequent Contributor
timestamp: January 03, 2021, 01:27:08 pm
content: Hi AllJust wondering, if using lower DC input voltage than what is indicated by the manufacturer of the sets such as RF amps, Active Antennas and HF Radios etc. For exmple, if it is to be used with 12V DC, can 9V DC input be used without causing any stress to the sets? I would think higher DC input such as 16 - 20VDC will definitely cause stress to the sets and shorten their lives.But lower DC voltages??? What do you think?

author: bob91343
author_rank: Super Contributor
timestamp: January 03, 2021, 10:23:25 pm
content: Usually not. There are always exceptions. Performance may be compromised, however.

author: vinlove
author_rank: Frequent Contributor
timestamp: January 05, 2021, 10:03:57 am
content: On the old receivers and RF amps, using lower input DC voltage gave quieter reception, so I have been using 9VDC for 12VDC input.I am also using 6V DC for 9V DC input for my old Sangean radio. The freq, display is a bit dimmer, but the reception is quieter with the lower DCV input.

author: vinlove
author_rank: Frequent Contributor
timestamp: January 05, 2021, 01:47:33 pm
content: Quote from: bob91343 on January 03, 2021, 10:23:25 pmCould you please elaborate more on the exceptional cases? Thanks

author: bob91343
author_rank: Super Contributor
timestamp: January 05, 2021, 10:36:18 pm
content: Sometimes lower voltage causes operation in an undesired mode, such as when there is a step up power supply (oscillator) or a regulator that uses a discharge tube.

author: vinlove
author_rank: Frequent Contributor
timestamp: January 06, 2021, 10:33:24 am
content: Would it actually cause damages on the power supply or regulator? If yes, what sort of damages are to occur onto which parts? The reasons for the damages?

author: bob91343
author_rank: Super Contributor
timestamp: January 06, 2021, 08:02:37 pm
content: I can't answer your question because each unit is different. I suspect it's possible to cause damage but beyond that I don't know. Operating in an odd mode can cause all sorts of strange things.

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 06, 2021, 08:19:09 pm
content: To elaborate from Bob’s answer: because the differences in circuitry one cannot possibly provide a “one size fits all” answer.The best is for you to experiment with the equipment and set up you have and perform measurements.Use a good variable power supply.
NSW "Empowering Homes" Solar/Battery Loan Offer - Page 1
Forum section: electronics / general

author: Halcyon
author_rank: Unknown
timestamp: December 24, 2020, 05:12:45 am
content: For those living in the state of New South Wales (Australia, not Austria), you might have heard of a scheme that was being trialled in the Hunter Valley area earlier this year. This has now been expanded (rather quietly I might add) to the following areas:BathurstBlayneyBlue MountainsCabonneCentral CoastCessnockDungogHawkesburyKempseyLake MacquarieLithgowMaitlandMid-Coast RegionMid-Western RegionMuswellbrookNewcastleOberonOrangePort MacquariePort StephensSingletonTamworthUpper-HunterWalchaIf you live in these areas, check outhttps://energysaver.nsw.gov.au/households/solar-and-battery-power/empowering-homes-solar-battery-loan-offerThe NSW Government are offering interest-free loans for up to $14,000 for a PV and battery system, or $9000 to retrofit a battery system to an existing PV array.I've already got a 5 kW system but have taken advantage of the $14k and added a second system in addition to batteries. The feed-in tariff on this plan is alsomuchbetter than the crappy 9.5c/kWh they currently give you. The FIT is based on demand and the price that's paid back to you is live. When I spoke to the guys from Sunbank Solar on the phone today, they mentioned that over the last few days, the FIT was as high as $2.34/kWh and the low was somewhere in the ballpark of 20-60c/kWh. Apparently in some places when demand is very high, the FIT can be more than $10/kWh. Regardless, they guarantee a minimum FIT of 6c/kWh. I would be surprised if most people with moderate power needs don't end up with a credit at the end of each quarter.However, if you want to you can also elect to stay with your current electricity provider.I did the maths based on my usage and system and I worked out that the solar upgrade + battery should pay itself off in no more than 4 years.
Powdered iron torroid  inductors...calculating core loss and inductance? - Page 1
Forum section: electronics / general

author: opampsmoker
author_rank: Regular Contributor
timestamp: December 21, 2020, 11:41:55 pm
content: Hi,Was just trying to follow Mag-Inc website’s guidelines on calculations for a 650W Boost PFC inductor….https://www.mag-inc.com/Products/Powder-Cores/Kool-Mu-Cores/PFC-Boost-DesignHowever, they base the calculations on the fact that they say that peak inductor current at 85VAC is 8.48 Amps.However, surely it should be more like 12 Amps (as the attached LTspice simulation shows).Does anybody have any good guides on how to calculate core losses for powdered iron torroid inductors? Also, how to calculate the inductance for a given number of turns and with a given DC Bias?
Boost converter LED driver and non-minimum phase instability - Page 1
Forum section: electronics / general

author: rt54321
author_rank: Newbie
timestamp: November 23, 2020, 02:53:35 am
content: Greetings All! Control theory conceptual question here. I've attached a schematic for reference.I'm trying to wrap my head around using a boost converter to drive a string of 10 LEDs with a constant current of about 100mA.In the diagram, Vout will be somewhere between 28 and 30V (I have used a bench supply to drive the LED string for testing). Input voltage is ~9V from a wall wart. The idea is to use an MSP430 to sense the current through the Rsense resistor, and adjust the PWM duty cycle of M1 to close the loop around the LED current.--> I am NOT directly controlling the output voltage of the boost converter - I'm controlling the output current. Do I need to worry about the converter's non-minimum phase behavior?

author: opampsmoker
author_rank: Regular Contributor
timestamp: December 20, 2020, 12:07:59 pm
content: Yes you do....here is a boost converter led driver in the free download ltspice simulator.You can fiddle with the feedback compensation components and see how you go if you wantYou can also change vin to your 9v...change the sense resistor etc, and fit it out for your situation. Get back if you have problems.Also attached is quik start guide to LTspice
PowMR MPPT Controller - Not 60A as advertised - Page 1
Forum section: electronics / general

author: cpuerror
author_rank: Regular Contributor
timestamp: December 18, 2020, 08:00:15 pm
content: These are sold as 60A MPPT controller at reasonable prices but they are not. The actual power output to the battery is more like 40-44A max and get really hot in the process.Perhaps the MakeSkyBlue ones are better after all?

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: December 18, 2020, 08:09:22 pm
content: Everybody lies.