hybridfree/eevblog-posts huggingface dataset:
problem sensing off-grid inverter output voltage - Page 1
Forum section: electronics / general

author: Xtal011
author_rank: Newbie
timestamp: November 02, 2021, 03:46:17 am
content: Hello everyone. I am designing an off-grid inverter and recently run into a problem whil trying to sense the output voltage with a differential amplifier.The problem is that as soon as I try to sense the voltage at the output the retrieved waveform is totaly distorted. Is there any way to sense the output voltage witout distorting the waveform??Attached to this post are the images with the schematics and the waveforms simulated in OrCAD capture.To further clarify the voltage sensed (yelow waveform) will later be fed into an RMS to DC converter.

author: dtmouton
author_rank: Contributor
timestamp: November 02, 2021, 06:54:36 am
content: The one thing I picked up is that the ratio of the values of the resistors in your voltage divider is very large. In this case the capacitance of the resistors come into play. Google the phrase "frequency compensated voltage divider".

author: Xtal011
author_rank: Newbie
timestamp: November 03, 2021, 05:40:47 pm
content: thanks for the idea, later I will simulate it and comment on the result.Adding to this answer, i simulated it and it did not work

author: richard.cs
author_rank: Super Contributor
timestamp: November 06, 2021, 12:12:33 pm
content: Looking at your schematics V_OUT_N is bouncing up and down at 400 V pk-pk which is not at all suppressed by your unbalanced filter (VO_L- and V_OUT_N are the same net). That's a bad idea from an EMC perspective, but it also means that the voltage measurement circuit needs to have very good common mode rejection to measure it the differential voltage in the presence of that signal. Does the measurement circuit rely on a floating supply to work? Capacitance across the isolation barrier can upset that sort of thing.I think I would start by fixing the filter, it needs to change to avoid producing awful noise, but that will probably also help your measurement.Side note, it also makes a difference which switching strategy you use. One approach puts the PWM on all the transistors, and the other just PWMs one side whilst driving the other at a leisurely 50/60 Hz.

author: Circlotron
author_rank: Super Contributor
timestamp: November 06, 2021, 12:28:27 pm
content: Low tech would be an effective solution here. A very small mains stepdown transformer would do the trick very nicely. No need for tight resistor matching. No common mode problems. Ground referenced secondary voltage. What's not to like, besides being unfashionable maybe?

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 06, 2021, 06:32:03 pm
content: Standard power transformers are not very linear. That could be worked around by using the transformer at less voltage than it's designed for, such as a 240V transformer on 120V or a 380V transformer on 240V.
OverVoltage - Page 1
Forum section: electronics / general

author: Bobtone
author_rank: Newbie
timestamp: November 01, 2021, 09:27:29 am
content: Hi, all! any help on my project... i have turnned a fuel generator to fuelless generator now the output voltage goes over the voltage reqiured, which can cause damage to senstive electronic devices. Which circuit can make to be safe of this problem? The output should be 220v-230v 1kw...

author: Kleinstein
author_rank: Super Contributor
timestamp: November 01, 2021, 10:30:12 am
content: Using a seprate gnerator suggest that this is off grid and thus not locked to an external stable frequency. With many of the generators the ouput voltage depends on the speed the generator is driven. The motor usually has some speed control, also to keep the frequency about right (e.g. 45-70 Hz).In addition some generators have additional voltage regulation for a limited range, e.g. to compensate for the votlage drop under load. If the genrator is driven too fast, the votlage control may not be able to compensate.

author: Bobtone
author_rank: Newbie
timestamp: November 01, 2021, 11:29:16 am
content: I understand but i have found a circuit which can protect my loads. In addition to, this generator is well designed to produce voltage at the frequency of 50-60Hz and given a gear lever to control the voltage within 110v, 220v, 250v and 300v which is not present in my case. So, I'm pretty sure my prime mover is changing the speed according to my loading, i'll soon find a good solution to this when i find an ESC for my prime mover maybe.

author: f4eru
author_rank: Super Contributor
timestamp: November 01, 2021, 06:33:27 pm
content: What is a "Fuelless generator" ?

author: m3vuv
author_rank: Super Contributor
timestamp: November 03, 2021, 06:33:16 am
content: good point what the fuck is a fueless generator?,sounds like some bollox from a nutjob to me!!
Synchronous upgrade for  dps3005, dps5005 - Page 1
Forum section: electronics / general

author: geo999
author_rank: Contributor
timestamp: November 01, 2021, 05:29:19 pm
content: Hi,beginner question here,is it possible to convert the dps3005 and similar power sources to a synchronous version ?Meaning, to replace the diode with a n-channel mosfet and use irf 2104 half bridge mosfet driver to drive both mosfets from the original pwm signal.The need here is for a more efficient power supply to use in a battery powered project.Any thoughts on this one ? is there any meaningful benefit for this conversion ?Regards,George
High efficiency, high PF AC to low DC conversion? - Page 1
Forum section: electronics / general

author: Nominal Animal
author_rank: Super Contributor
timestamp: October 30, 2021, 11:02:18 pm
content: The question is, are there commonly used circuits that would convert 230VAC to say 5.15V at max. 2.1A at high efficiency (>90%) and high power factors (>90%)?Just out of pure interest (I'm a hobbyist, not an EE), I looked at typical circuits used to generate say a typical USB wall wart DC voltage (say 5.15 V, 2.1 A).TI Webench designs top at about 91% efficiency, and don't seem to have any kind of power factor correction.I don't actually need this for anything, I'm just interested in knowing where the technical limitations for mass produced items currently stand.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 30, 2021, 11:10:29 pm
content: I don't think there's any limitation, just that there's no point; CE doesn't require it below 50W or so.If you wanted to, you could reasonably well scale down a 100W adapter, with PFC, and run it at 10W. It may be a bit tricky on account of the low currents being a bit less effective at switching; the effect being, the dynamic range / responsiveness stinks more than usual, causing worse PF. But something's still better than nothing (i.e. straight rectifier and cap) so it might still be okay as far as satisfying your curiosity.Part of that also being energy lost in strays, which isn't such a big part of the total at scale, but may be relatively significant at this level. So, getting over 90% might be quite a challenge.Tim

author: nctnico
author_rank: Super Contributor
timestamp: October 30, 2021, 11:47:49 pm
content: In the past I have used a passive PFC circuit that uses a center tapped flyback transformer. Something along the lines described in these patents:https://patents.google.com/patent/US6005780A/enhttps://patents.google.com/patent/US5995383A/en

author: David Hess
author_rank: Super Contributor
timestamp: October 31, 2021, 02:38:24 pm
content: Power factor correction will not normally be applied at such lower power levels, so finding examples of it will be difficult.If you want to experiment safely, nothing prevents implementing power factor correction and a switching regulator after a 50/60 Hz power transformer to step down to 12 or 24 or whatever volts AC. Some older off-line switching power supply designs did exactly this.
Lithium Cell Inductive response - Page 1
Forum section: electronics / general

author: agganitk
author_rank: Newbie
timestamp: October 28, 2021, 12:17:43 pm
content: Hello ,I am working on BMS. I am working on timing of discharge mosfet switching off. If Switching off too fast, then mosfet might get damaged due to inductive response of cell.Does any one have data or guideline for L of NMC or LFP battery so I can calculate V from L dI/dt before I jump into real experiments.Thanks

author: Siwastaja
author_rank: Super Contributor
timestamp: October 28, 2021, 01:28:43 pm
content: Cells internally are well sandwiched "capacitors" with little inductance, most comes from the fact how external connections are placed; side by side, or from opposite ends? Then wiring between the cells, and finally the wiring exiting the pack to your circuit. Remember to use worst-case wiring if there is a possibility someone uses loose 5-meter cables all over the place instead of the 10cm nicely parallel stub you though everyone would use.You get close by simply modelling the battery pack and wiring as a wire loop of the actual pack geometry, assuming the inductance between + and - terminal is just caused by the distance of the terminals. Once you have the geometrical drawing, you'll find inductance calculators online.

author: mzzj
author_rank: Super Contributor
timestamp: October 28, 2021, 05:00:34 pm
content: Fairly easy task IF you don’t plan to implement short-circuit protection.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 29, 2021, 09:39:10 am
content: I didn't struggle with short-circuit protection. But it requires quite large MOSFETs and understanding of the SOA curves. And some capacitance and large TVS diodes because the avalanche ratings of even large MOSFETs are not that great.
Battery life and total throughput vs DOD - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: October 28, 2021, 02:12:39 am
content: A battery manufacturer might say a certain battery will last for 300 full discharges or 1000 partial discharges. In both cases the aggregate energy throughput might be similar. Ignoring time, is there some kind of more or less constant correlation between battery life and total Joules or Watt/hours throughput?

author: David Hess
author_rank: Super Contributor
timestamp: October 28, 2021, 03:22:50 am
content: No, because there are different wearout mechanism at play.Charging and discharging cause mechanical strain in the structure of the battery which damages the electrodes and separator. But independent of this in a lithium cell, the voltage across the electrolyte causes damage through electrolysis, so maintaining a high charge state damages the cell by itself. Supercapacitors have this problem also while lead-acid, NiCd, and NiMH cells do not beyond electrolysis of water which is reversible.

author: trobbins
author_rank: Frequent Contributor
timestamp: October 28, 2021, 10:29:08 am
content: Circlotron, that characteristic is what is generally seen for VRLA batteries designed for cycling and standby/cycling. At some level of standby application the performance of the battery degrades from age as there are not enough cycles in its life to reach end of service life from that aspect.For VRLA that effect may be compromised by cell variations/spread in a monobloc, or monobloc variations in a string, so there also needs to be a maintenance/monitoring effort to avoid those variations from prematurely ending the life of a battery bank in an energy storage system.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 28, 2021, 10:59:59 am
content: Assuming we talk about li-ion, you get a lot more throughput by limiting DOD. Say you get mere 500 cycles at 100% DOD. At 50% DOD, it's not going to be 1000 cycles, it can be well be 5000 cycles or even more. Details vary but this is the general pattern.
Flyback Transformer Selection - Page 1
Forum section: electronics / general

author: beginner43
author_rank: Newbie
timestamp: October 23, 2021, 08:09:45 pm
content: Hello there,The flyback transformer I shared the link of says 4-18Vin gives 400V output voltage. It has a 1:10 conversion ratio. What I don't understand is shouldn't Vout= Vin*Nps? So as you change the input voltage, shouldn't the output voltage increase? Sorry if this is a stupid question.https://media.digikey.com/pdf/Data%20Sheets/Sumida%20PDFs/13324-T087_Spec.pdf
restoring power myth? - Page 1
Forum section: electronics / general

author: vivi-d
author_rank: Regular Contributor
timestamp: October 15, 2021, 07:16:51 pm
content: Is it true that there is a danger to electronics when the power is restored after a blackout? Everyone I know seems to think that there is a large "surge" that happens when power is restored.What really happens?

author: coppercone2
author_rank: Super Contributor
timestamp: October 15, 2021, 09:25:49 pm
content: Yeah, this happened to me recently, when the power comes back it likes to blow up MOVs. I got a whole house surge arrester after I had to replace 4 power strips and a clock and something elseI don't know why but it seems that power up has regulation problems.. it might be beneficial to keep the breakers off until you know it stabilized. at least thats what I would like my house to do but its a little pricey for a once in 20 year occur aceand possibly it damaged appliances, i got a dehumidifier and portable AC with problems only 1 year of ownership (including the event).. not sure if it got touched by a surge or if it was just built really bad.. still need to investigate.

author: james_s
author_rank: Super Contributor
timestamp: October 15, 2021, 10:18:46 pm
content: There is a massive surge of demand as all of the motors in things like refrigerators try to power up all at once, so you can get some pretty nasty spikes and brownouts. It really is better to shut off what you can prior to power returning just to ease the load on the system. I've never had any equipment damaged by it but why risk it?Have you noticed the way the lights dim for an instant when an air conditioner, heat pump or in some cases even a domestic refrigerator kick on? Now imagine potentially thousands of those being switched on all at once.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: October 16, 2021, 02:53:41 am
content: We had a about a 30 second power outage and then after that our washing machine was showing a water level fault. So we called a repairman. And he showed me how to reinitialize the system to factory start and it worked fine. That was in the manual. Maybe I should have looked at the manual.

author: Faringdon
author_rank: Super Contributor
timestamp: October 17, 2021, 11:19:59 am
content: Yes there is a large inrush current surge into all the devices when the mains comes back on...charging up all the input capacitors.This high current puts a lot of energy into the stray inductance of the mains grid wiring....when the inrush stops, the energy is still in the stray inductance, so it causes an overvoltage spike to all equipments.If the mains grid wiring had zero stray inductance (impossible , i know), then there would be no bad surge problem when the power gets restored to the grid.By "grid", i mean the "national electricity supply system."
Suggestion for  NiMH AA cell charger/discharger - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: October 14, 2021, 02:37:08 am
content: I'm looking for a charger for AA NiMH cells that will charge each cell individually, and also do a discharge and capacity measurement before recharge. I have several other chargers, one a 15 minute fast charger that I don't think pumps them all the way up, and it's end of charge termination seems to vary a bit from cell to cell, e.g. the one on the rightmost position always gets charged maybe 30% longer than the other three. And have this cheap-ass thing that charges in pairs and sort of works but I'm not that happy with it, and the radio that these cells get used in has an internal charger but of course over a period of time the cells get all unbalanced. So... can anybody recommend something I should look at? Preferably under say USD$150 if possible.

author: IanB
author_rank: Super Contributor
timestamp: October 14, 2021, 02:50:14 am
content: My go-to for this has always been the Powerex MH-C9000. There is apparently an update with new packaging, although I suspect the insides are similar:https://mahaenergy.com/mh-c9000pro/

author: Berni
author_rank: Super Contributor
timestamp: October 14, 2021, 05:35:32 am
content: I have one of these cheep Chinese chargers:http://www.liito-kala.com/page92?product_id=6The company that makes them seams to be focused on battery stuff and they make plenty of different models with various features, they are pretty well regraded online and sell on all the usual channels like AliExpress Amazon etc.I use mine for NiMH AAs and AAAs along with 18650 cells. Works well, its simple to use, it autodetects the cell type, the charge current is adjustable, it displays the cell voltage and counts charge in mAh, can do a discharge test too. Only thing about it is that the button interface is a bit confusing and the battery internal resistance measurement feature doesn't really work (it still measures a good low resistance even on worn out cells)

author: Circlotron
author_rank: Super Contributor
timestamp: October 21, 2021, 08:42:45 am
content: Quote from: IanB on October 14, 2021, 02:50:14 amGot one yesterday. Looking good! The difference seems to be the new one doesn't have the charge/discharge X cycles option. Thanks for the suggestion.
Relay Welding - Page 1
Forum section: electronics / general

author: Revky27
author_rank: Contributor
timestamp: October 20, 2021, 12:29:49 pm
content: Hi All,I am trying to estimate the welding time and current of a relay. Does anyone have come across some usefull resources as I am finding it tricky to get any kind of resource or application note on this to get a best guess value.Thanks
hombrew battery pack charging wierdness. - Page 1
Forum section: electronics / general

author: m3vuv
author_rank: Super Contributor
timestamp: November 03, 2021, 06:18:59 am
content: Hi all,i have a homemade 13s/9p battery pack made with lithiun ion colbalt 18650 cells,it works fine but one cell group never seems to fully charge see pic,it works fine but just the one cell bank never seems to fully charge,the bms is set to cut off at 4.18v when charging, but as you can see one bank only gets upto about 3.9v ,other than that it seems fine any ideas ?

author: tunk
author_rank: Super Contributor
timestamp: November 03, 2021, 11:21:49 am
content: No expert on this, but I'm left with the impression that balancing can take a long time.Maybe you could try to charge that cell bank separately. And if it happens again, oneor more cells in the bank could possibly be bad.

author: m3vuv
author_rank: Super Contributor
timestamp: November 04, 2021, 07:57:23 pm
content: Well ive tried with the smart bms parameters set to charge balance also static balance,doesent seem to make any difference,the pack doesent self discharge well at least the groupe in question doesent,if there was a bad cell in the groupe i imagine that would happen or the battery temps go up ?.
Why is there reverse current on Forward Converter demagnetization? - Page 1
Forum section: electronics / general

author: ckrj21
author_rank: Newbie
timestamp: October 10, 2021, 04:28:21 pm
content: Hello,(no load and no demagnetization winding)for magnetizing the primary winding, the single MOSFET pulls the terminal to ground. Current starts to increase linearly together with magnetic flux inside the ferrite. Next the MOSFET is switched off and the gate is discharged, and the drain source voltage starts to rise. Once the body diode is in reverse bias the drain-source voltage drops back to ~0 V and a reverse current goes through the primary which discharges to 0 A right until the MOSFET is switched back on again.So at the transition from on to off of the MOSFET the current completly reverses, but the primary voltage stays mostly the same, since the current change is positive except at the transition.Now, to my understanding this is not right behaviour. The change of polarity after switching the MOSFET off should mean that the primary inductance has a reverse voltage but the current should still be positive and start discharging towards 0 A.How could there possibly be negative current?Since there is no demagnetization winding the core should saturate, could that explain the negative current? Could there be a problem with the measurement at the 3 Ohm shunt resistor at the source pin?

author: Faringdon
author_rank: Super Contributor
timestamp: October 10, 2021, 04:44:31 pm
content: Do you mean a single transistor forward?The attached LTspice shows one that doesnt give current like you show

author: ckrj21
author_rank: Newbie
timestamp: October 10, 2021, 05:03:07 pm
content: Thank you, LTSpice is very good and pretty much shows the exact same measurements.I forgot to tell you that I had no load and there is no demagnetization winding present.Doing that you get the same:So essentially it is just an inductor now. How can there be reverse current now? Yes there is a high reverse voltage briefly, but it is normally explained that the inductor acts like a source so it should increase the current?

author: ckrj21
author_rank: Newbie
timestamp: October 10, 2021, 05:23:09 pm
content: yeah ok it makes all sense actuallyIt was just confusing because I didn't expect the reverse voltage to be able to drive the current into negative values. It just looked like it jumped there. Thanks.

author: Faringdon
author_rank: Super Contributor
timestamp: October 10, 2021, 08:01:22 pm
content: OK thanks, here is the one tran forward with the demag winding , in LTspice, as attached.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 10, 2021, 10:04:01 pm
content: It appears you're in class E. The flux charged into the inductor, goes into the drain capacitance, which charges back into the inductor, recirculating the energy. No energy is consumed so the switch returns to negative current, then positive on the next driven cycle.Tim
lipo battery charger - Page 1
Forum section: electronics / general

author: merlinuk32
author_rank: Newbie
timestamp: October 17, 2021, 04:36:52 pm
content: hi all i would like to build my own charger for a nominal 72v full charged 84v lipo pack but i would like it to be able to charge with up to 60 amp and i would like it to have the ability to have its smprage going out to be controled via a micro controler any help would be nicei am thinking about a buck converter as the mane arcitecter but i cant seem to find a buck controler to do this taski would also like it to oparate based on constent current constent voltage both being able to be set by the micro controler

author: tonyh88
author_rank: Regular Contributor
timestamp: October 17, 2021, 04:50:18 pm
content: From the question I am just wondering if you have prior experience designing that kind power eletconics hardware because it is not trivial to build that charger.Also may I ask what this charger is for? 72V @ 60 amps is quite a lot of power. Some kind of E-Bike?I would suggest to look for something off the shelf if the goal is just to have something that works.If you are looking for a project to learn this can be a fun project but it won't be super easy

author: merlinuk32
author_rank: Newbie
timestamp: October 17, 2021, 05:23:01 pm
content: hi there no i do not have any exspariance with high power eletronics hightest i have delt with is 12v projectsand i would go off the shelf but its ether crazy exspensive or imposible to find documentatin on how the protocal is usedand yes its for a home built e trike with the battery pack about 11kw hence why i want a high power chargerand i am always up for a chanalge
HV Supply - Page 1
Forum section: electronics / general

author: beginner43
author_rank: Newbie
timestamp: October 06, 2021, 11:06:16 am
content: Hello there,I need 2500V output voltage and 1mA continuous, 16mA peak(duration 3us) output current in my circuit.Vin=24VDo I have to design my circuit according to 16ma? For example, can I use the product whose link I shared?If this product is not suitable, which topology or component would you recommend?

author: Marco
author_rank: Super Contributor
timestamp: October 06, 2021, 12:54:37 pm
content: You didn't share a linkHow often do those peaks occur? What kind of ripple can you accept?

author: bob91343
author_rank: Super Contributor
timestamp: October 06, 2021, 05:49:08 pm
content: Just use a microwave oven transformer.

author: Gyro
author_rank: Super Contributor
timestamp: October 06, 2021, 06:05:24 pm
content: Quote from: bob91343 on October 06, 2021, 05:49:08 pmNot really a suitable, or safe, suggestion when the OP is looking for a 2.5W supply!Quote from: Marco on October 06, 2021, 12:54:37 pmGood question. Short, low duty cycle peaks can probably be handled by the output capacitor.
Audio system pop - Page 1
Forum section: electronics / general

author: jeffjmr
author_rank: Regular Contributor
timestamp: October 12, 2021, 04:08:43 pm
content: Struggled to pick the right forum for this as it applies to a couple.My audio system exhibits a loud pop when virtually anything is cycled on or off in my house. And it is getting progressively worse.It started out when my AC compressor would start or stop, then slowly progressed to even a low wattage LED light if on the same CB.All my audio components either have RF line filters on their power cords or are plugged into either a noise filtered UPS or a bucking transformer with a filter. So this sounds like something more related to my mains electrical panel.Any ideas how to start troubleshooting this issue?Thanks,Jeff

author: f4eru
author_rank: Super Contributor
timestamp: October 13, 2021, 10:45:22 pm
content: isolate which component of the system is doing this.check the electrolythics inside for ESR

author: bdunham7
author_rank: Super Contributor
timestamp: October 13, 2021, 10:51:15 pm
content: Not to nitpick, but I think your forum choice reflects the wrong path!But maybe it will work out.What is the 'audio system' and under what conditions--i.e. what are you listening to--does it happen?

author: jeffjmr
author_rank: Regular Contributor
timestamp: October 15, 2021, 12:57:11 am
content: Yamaha V685 used as a preamp only. Dynaco ST-70 driving a pair of Altec Lansing A5X VOTTs.Matters not what I’m listening to. Happens with no program selected. Preamp on or off. Volume muted or not. All light switches, flat screen TV powered on or off makes the pop. Those are all on the same CB, but the AC compressor is not and it is the worst. So it is the tube amp that is picking it up. I can change receptacles but still the same CB. Going to get a long extension cord so I can be on a different CB but with the AC doing it I don’t expect a difference.Thanks,Jeff

author: bdunham7
author_rank: Super Contributor
timestamp: October 15, 2021, 01:09:14 am
content: OK, I assume the Dynaco and the Yamaha amps have two-prong cords? How is the system grounded--perhaps in more than one place? What other components are connected in any way to the system (even the powered off ones) and is there a cable (Cable TV, internet or antenna) going to the system at any point?If you think the pop noise is originating in the amplifier (whether it is at fault or not) then try disconnecting everything going to the amplifier except the speaker cables and power cord. And then try flipping the power cord and try to replicate the noise either way.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 15, 2021, 02:13:44 am
content: Have you tried connecting the speakers to the integrated amplifier in the Yamaha? The low level analog output is more likely than not just for a cheap way to add external amplifiers for audio in other rooms and it wouldn't take much noise pickup to really degrade the signal. Modern digital amplifiers are very good.For reference, truly high end analog audio is differential and there's a good reason for it.
The digital battery, what is it ? - Page 1
Forum section: electronics / general

author: abdulbadii
author_rank: Frequent Contributor
timestamp: October 01, 2021, 02:40:34 pm
content: Was given away a battery on which the "Digital battery" is printed mainly, so is "12V", with size almost 2/3 of AAA size and the same diameter or slightly more.So the question is what actually is the digital battery, what is its definition?

author: BrokenYugo
author_rank: Super Contributor
timestamp: October 01, 2021, 04:25:27 pm
content: Sounds like a regular off brand chinesium A27 battery, nothing actually digital about it.https://en.m.wikipedia.org/wiki/A27_battery

author: Gyro
author_rank: Super Contributor
timestamp: October 01, 2021, 07:33:23 pm
content: Quote from: abdulbadii on October 01, 2021, 02:40:34 pmIt's either leaking or it's not.

author: EPAIII
author_rank: Super Contributor
timestamp: October 10, 2021, 03:23:16 am
content: Just one more sales gimmick.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2021, 10:06:47 am
content: In late nineties, all headphones suddenly transitioned into "digital headphones".One could think this had something to do with replacing analog audio with digital comms, or adding some DSP, but this was not the case. It was just a trend word misused by most headphone manufacturers. It had to do with digital CD audio. i.e. portable CD players replacing the cassette "Walkmans".The same kind of marketing was seen in batteries, carry cases and whatnot when digital cameras were groundbreaking and trendy in early 2000's. Suddenly a simple bag could be transitioned into "digital". It's kind of refreshing to see such retro marketing 20 years later now.

author: Circlotron
author_rank: Super Contributor
timestamp: October 10, 2021, 12:01:31 pm
content: I put analog paper in my printer once. Messed it right up. Now I only use digital paper.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2021, 12:21:22 pm
content: That one has "kind of" point that it's optimized for use in digital printers (both inkjet and laser, which involves some compromises), at the expense of it not being optimal for writing with pencil. For a pencil, a tad rougher surface could be better.But the headphones have no "optimization" of any kind for such D/A signal source. In case of batteries, this "digital" titlesometimesmeans they are high-power cells because digital cameras were known to be power hungry. Unsurprisingly, before the digital camera era,camera batterieswere sold, and expensive. Even back then, charging up the flash capacitor took quite some peak current, cameras were used outside so possibly at cold temperatures, and you didn't want the camera to die during use. So these "digital" brands may be higher current, more expensive cells, compared to ones sold to be used in remote controls for example.But eventually, coming to 2010's, most digital cameras transitioned into rechargeable li-ion packs specific to the manufacturer. I haven't seen "digital" batteries in a while.
Can you buy inverter power modules? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: October 02, 2021, 01:16:49 pm
content: Hi,Can you buy single phase Inverter power modules for converting DC to UK/EU/USA/AUS mains AC?Eg like you can buy Vicor modules for DCDC, can you buy the same kind of thing, but an inverter?

author: Stray Electron
author_rank: Super Contributor
timestamp: October 02, 2021, 07:48:33 pm
content: Is that a serious question?If so, yes. Lots of people sell them and they've been available for many years. I bought this and plan on installing it in my truck. Mean Well TS-400-112F <https://power.sager.com/ts-400-112f-2719668.html>. I bought it brand new for about $85 on Ebay. The link above has a link to a complete data sheet.The newer Ford trucks have an optional 7200 Watt DC to AC inverter that's powered from a 2nd alternator (24 volt!) that's mounted on the engine. Some people have already used them to run their entire homes during an emergency.

author: Faringdon
author_rank: Super Contributor
timestamp: October 02, 2021, 07:58:15 pm
content: Thanks,but sorry, i was referring to just the power stage, eg like as in a vicor module, not the completed product.

author: Stray Electron
author_rank: Super Contributor
timestamp: October 02, 2021, 08:19:44 pm
content: Individual modules aren't common but I have seen exactly one. I don't recall who made it but it wasn't a common name and it looked like it was probably made for the military based on the markings on it. It was part of a test station made for some kind of military equipment and looked very similar to a Vicor module. It didn't work so I pitched it so I can't tell you anything further about it but IIRC the output was 400 Hz and the input was 28VDC.Mean Well makes complete units, have you checked to see if they sell just modules? OTOH I can tell you that based on the unit that I have that there's no wasted space inside of it so a "module" won't be much smaller. The only thing that might be possible to leave out is the AC outlet itself. If you just want the guts, your best bet would probably be to buy an OTS Mean Well or other commercial unit and take it out of the case and remove the bits that you didn't want.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 02, 2021, 11:26:24 pm
content: There are inverter boards that accept 380V or so DC and convert it to 240V AC.

author: Faringdon
author_rank: Super Contributor
timestamp: October 03, 2021, 02:37:05 pm
content: QuoteThanks, i must admit ive struggled to find them.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 03, 2021, 10:25:31 pm
content: Here's one:https://www.aliexpress.com/item/1005001450606013.html
Mosfet Turn on/off time - Page 1
Forum section: electronics / general

author: agganitk
author_rank: Newbie
timestamp: October 03, 2021, 03:52:00 pm
content: HelloI am trying to calculate mosfet turn on & off times. I followed attached vishay app note. At the end of app note, an example is given for calculation. I did calculation and all result are matching except high lighted one. I cross checked manytime my calculation but couldn't find any mistake. please let know where i am wrong.For example, I should get 197 ns in result but getting 472 ns.
Coping C surge current on AC jack pin of a device - Page 1
Forum section: electronics / general

author: abdulbadii
author_rank: Frequent Contributor
timestamp: October 02, 2021, 01:36:53 am
content: Is it true that some electronic products have C surge current on AC jack pin at power start suppressed simply by makeing it covered/sealed under silicon glue?

author: bob91343
author_rank: Super Contributor
timestamp: October 02, 2021, 03:53:42 am
content: C surge current? Maybe you mean capacitor. Suppressed with glue?I can't figure out what you are talking about.
Nickel Battery charger circuit - Page 1
Forum section: electronics / general

author: Saitama
author_rank: Contributor
timestamp: September 29, 2021, 07:10:35 pm
content: Hello! I really need a NiMH/NiCad battery charger and I want to make one. The problem is that I haven't really messed around with these kinds of batteries. I did a bit of research and I'm pretty sure it needs a Constant Current to charge properly, but from what I saw on the internet, most of the circuits are just voltage step-down converters and they use CV instead of CC. I know that I should make a proper circuit, but I don't have much parts on hand and I have to have it done by tomorrow. So what do you guys think? Do you have any suggestions?The whole thing is going to be powered from a USB power brick, so the input voltage is stable 5V.

author: geggi1
author_rank: Frequent Contributor
timestamp: October 01, 2021, 09:18:44 am
content: NiCad batteries is constant current charge.As far as i remember you are suppose to charge with 1/10 of the capacity.The charger curcuit can be as simple as a two transistor curcuit with a few resistors.Just google constant current circuit and you will find several.

author: Saitama
author_rank: Contributor
timestamp: October 01, 2021, 06:54:17 pm
content: Thanks for answering!I considered a constant current source, but I was a bit worried, because near the max capacity, voltage must be increased to maintain the current. I was concerned, that the higher voltage would damage the batteries.
18650 CHARGE CYCLE QUESTIONS - Page 1
Forum section: electronics / general

author: m3vuv
author_rank: Super Contributor
timestamp: September 26, 2021, 04:40:38 am
content: Hi all,when manufactures quote lion battery cell life in charge cycles,does a charge from say 50% to 75% count as a charge cycle,ie am i better off charging my batterys often to top them up or use them untill the lvc then charge?

author: Kleinstein
author_rank: Super Contributor
timestamp: September 26, 2021, 06:06:41 am
content: The charge cycle are usually from "empty" to full, so with essentially the nominal capacity at the start and than with fixed votlage limits. At least this is how it should be.As far As I understand it the cell suffer from getting very full and getting very empty. They kind of adjust the upper voltage limit to still get the wanted number of cycle. Cycling from 50% to 75% is likely much less stress, but only using 75% to 100% or 0-25% cycles may be nearly as bad as doing full cycles, at least for the parts effected by the extremes.As much as I understand it is better to no regularly charge / discharge all the way to the extremes. So more like aim for a 20% to 90% cycle, though at the low end one usually does not have so much control as one may need a nearly full charge at some points. So one may have to recharge sometimes even if still at 50% or 70%.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 26, 2021, 06:16:16 am
content: Cycle life is regarding full cycles between 100% and 0%, using the standard charging and discharging conditions like current, stopping condition etc. specified in the datasheet.Partial cycles have the tendency of wearing out the cell much less than expected from the amount of charge transferred. For example, if a cell is rated for 500 cycles 100%-0%, using it only between 70%-20% (i.e.: depth of discharge is 50% instead of 100%) increases number of such cycles way beyond the expected 1000 cycles, can be 5000-10000 cycles for example.There are other factors too, for maximum cycle life avoid charging at low temperatures (optimum would be somewhere around 30degC), and limit charging current near full. For example, if you have to fast charge at 0.8C, instead of running at 0.8C all the time, charge at 0.9C until 4.0V then at 0.6C. Small optimizations like that can have big difference.But all the exact details depend on the actual cell pretty much. Even given the same cathode chemistry, different manufacturers have their own different secret sauces which behave differently.

author: wraper
author_rank: Unknown
timestamp: September 26, 2021, 06:54:10 am
content: To maximize life, it would be preferable to not discharge below 20% and not charge above 80%. Charging above 85-90% is worse than discharging to 0 (if you don't leave it in discharged state for long).
Fluxgate current sensor without equal saturation of core in both directions? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: September 25, 2021, 12:27:55 pm
content: Hi,What if the schem on fig3, page 3 (of the below) is done without the compensation error amplifier , U2?Fluxgate current sensor:http://www.cpdee.ufmg.br/~troliveira/docs/papers/Induscon_2018.pdfThis article was sent to us by our Chinese associates, who are offering us ferrite nanocrystalline cores so we can do this.The article , and its predecessor, has been known to me, and mutiple of my previous companies, for the past 15 years, and the article , and its predecessor, has been freely available on the web for >15 years.

author: David Hess
author_rank: Super Contributor
timestamp: September 25, 2021, 06:50:24 pm
content: Quote from: Faringdon on September 25, 2021, 12:27:55 pmThe compensation balances the flux in the core to zero where linearity is maximum because the core is acting as a null detector. Operating this way, the gain and linearity of the core is removed as an error term.
Battery powered truck - Volta - Page 1
Forum section: electronics / general

author: woodchips
author_rank: Frequent Contributor
timestamp: September 16, 2021, 09:43:44 am
content: Just reading Machinery Market and they have a short article about the Volta Trucks new Volta Zero battery powered truck.It is 16 tonne, two axle, so that must be the maximum vehicle weight.How much of that is vehicle, how much batteries and how much payload? No answers in the article.It is interesting reading road tests etc on battery cars, and their weight. Some are as high as 2.5 tonnes. Is this really feasible? A diesel 16 tonne truck has a payload of, what, 8 tonnes? If you then have to take ? tonnes off for batteries?It is described as a city truck, so not hacking up and down the motorways but even so a 10 hour day driving in a city requires, what, about of energy and hence batteries. Is is a hybrid, doesn't say.Seems to me that battery power fits well into a certain percentage of vehicle use, but the rest it doesn't. Has anyone got an electric car and tows a caravan or trailer? And not just down the road but from the south to the north of the UK on holiday, or delivering items.
BMS CHARGING CHECK - Page 1
Forum section: electronics / general

author: agganitk
author_rank: Newbie
timestamp: November 05, 2021, 08:51:24 pm
content: To check current thorugh BMS, I have 3000W power supply and Dummy Resistive load. I succesfully checked DISCHARGING currents as per attached diagram.But to check CHARGING, I am not sure. Should I use another aux supply to powerup BMS for CHARGING checking? Just afraid of equipment getting damage. Should I add diode in aux supply for protection?
IRG4PC50UDPBF discontinued - Page 1
Forum section: electronics / general

author: aless2056
author_rank: Contributor
timestamp: September 14, 2021, 01:11:29 am
content: Guys, I don't know if you know the equipment for the treatment ofplastic film for corona effect, called corona treatment.This equipment is an H Bridge formed by igbts transistors and in the H bridge, we have a transformer that raises the secondary voltage to about 10KV and applies an electrical discharge in a plastic film to make the impression afterwards.I have equipment that uses the IRG4PC50UDPBF, this item has been discontinued, can someone help me find a replacement for it. I tested some and they worked, but there is a condition in which a leakage of 10KV can occur and in this leakage current, I have the current transformers that monitor the current and prevent burning by cutting the trip. With the IRG4PC50UDPBF I never had a burning problem, but with the replacements I tested, they all burned in this condition.Can someone tell me a replacement for the IRG4PC50UDPBF, it doesn't have to be from the IR, it can be from another manufacturer?
bms app - Page 1
Forum section: electronics / general

author: m3vuv
author_rank: Super Contributor
timestamp: September 13, 2021, 11:00:49 am
content: Hi all i have a 13s smart bms,i think its made by ltt i think,the bt app is the one with the elephant on it,i cant pronounce its name its chineese,if ppl are familiar with it,can anyone tell me the minimum android version it will work on?,ie ics gingerbread ,oreo etc,tia.

author: m3vuv
author_rank: Super Contributor
timestamp: September 13, 2021, 11:01:59 am
content: Surley to god someone can answer this the app is called xiaoxiang.just need to know the lowest android version to use as i have an old galaxy gt-i9100 running a custom rom running android version 8.1.0,trouble is tho,gps dont work with this rom/android version,and it eats the battery,so need to know what phone to replace it with and the lowest android version etc,have emailed james@lithiumbatterypcb.com,thats the tech support for the bms,basicaly the tech support cant understand english and are as much use as tits on a bull!!.TIA.
TL431: Calculation of r & c for tl431 feedback loop in dc dc converter - Page 1
Forum section: electronics / general

author: Arb32
author_rank: Newbie
timestamp: September 12, 2021, 01:10:36 pm
content: Hi I was designing a dc dc converter using LM5030I was using tl431 and pc817 for designing feedback loopI know two resistors r5 and r3 are used to set the voltagebut i have seen in many places c1 r2 and r4 are used, they are related to something type 2 compensatorI am a newbie to this and the materials available over the internet are confusing ,can anyone tell why there resistor capacitors are used and how to calculate them

author: iMo
author_rank: Super Contributor
timestamp: September 12, 2021, 04:15:06 pm
content: https://www.onsemi.com/company/news-media/blog/innovation-forum/single-capacitor-is-enough/

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 13, 2021, 04:34:47 am
content: I would rather have the R+C in the design, and simply set the resistor to zero if it isn't needed. Relying on the supply resistor, makes some assumptions about the supply voltage and ref/LED currents which may not be true in general (for any output voltage).And won't apply at all, for designs where an aux supply powers the feedback circuit, jointly or independently of the regulated supply -- that "fast lane" path simply doesn't exist in such a case. (This is particularly relevant for high output voltages: dropping ~10mA to feed the LED, would require a zener or other regulator to avoid overvolting the TL431, and would be a huge waste of power at 100V+. An AS431I or TLV431 may be helpful (lower minimum regulating current), but running the opto at lower current also makes it slower, and more noise sensitive.)Somewhat aside, sometimes a capacitor from REF to GND helps stability -- this being primarily related to RFI coupling into the pin, which is rectified by internal circuitry, shifting the operating point. Up to 220pF is usually enough to deal with that, without affecting the control loop much.As for calculating values, meh, 10nF + 100k is a good starting point for most designs. Step load testing is the surest approach. Exact values are hard to predict, as the transfer function of the system isn't easy to determine (and may simply not exist, in the case of poorly stable, hysteretic or chaotic systems).Tim

author: PKTKS
author_rank: Super Contributor
timestamp: September 13, 2021, 07:53:30 am
content: I have seen a lot of these...Most designs use the 3 pole type 3 compensation networkAnd even some exotic ones add a capacitive zener somewhere..The paper is a good reading although type 2 networks are less frequently i never ever found non compensated 431 at least type 2Paul
Datasheets for Duracell Alkaline Ultra D Type & AA Type - Page 1
Forum section: electronics / general

author: thelearner
author_rank: Contributor
timestamp: September 07, 2021, 06:52:04 am
content: Hello,Does anyone have datasheets for the following batteries from Duracell?1. Duracell Ultra Alkaline AA Batteries2. Duracell Ultra Alkaline D BatteryProduct Links1. Duracell Ultra Alkaline AA Batteries -https://www.amazon.in/dp/B014SZOORC/?cstrackid=103c188f-36e9-425d-8929-fac8be987509&tag=duracin0e-212. Duracell Ultra Alkaline D Battery -https://www.amazon.in/dp/B014SZPBM4/?cstrackid=fdc41b33-4ecb-4d4a-a74f-cdcce0a26c40&tag=duracin0e-21TIARegards,thelearner