hybridfree/eevblog-posts huggingface dataset:
EMF X2 caps ratings question - Page 1
Forum section: electronics / beginners

author: Bobson
author_rank: Regular Contributor
timestamp: June 06, 2024, 07:16:14 am
content: Got a box of Okaya 250V EMF caps. There are designations "1414 125V, 1283 250V". I understand that these are UL conformance ratings, but could not decide if I can use them as X2 caps with 230V line. Why UL 1414 125V rating?tia

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 07, 2024, 03:32:09 am
content: Can you show a photo?

author: Bobson
author_rank: Regular Contributor
timestamp: June 07, 2024, 04:59:14 pm
content: Here they are.

author: Gyro
author_rank: Super Contributor
timestamp: June 07, 2024, 06:21:11 pm
content: The UL etc. markings will cover things like flammability. Unless the package specifically includes the characters X/ X1 / X2 on it, it is not suitable for across-the-line mains use. X markings have specific meaning in terms of breakdown voltage, and most importantly, self-healing capability.Edit: Sorry, looking again at the photos, they do have an X ratings!

author: Bobson
author_rank: Regular Contributor
timestamp: June 09, 2024, 04:53:02 am
content: Found Panasonic ECQUV series datasheet with the same designations,https://industrial.panasonic.com/cdbs/www-data/pdf/RDI0000/RDI0000C291.pdf.It also states UL 1283 250V and UL 1414 125V. Strangely enough, UL 1414 does not deal with X2 type, only X1 and Y1/Y2, and states 125V only for double-insulated equipment without grounded chassis.My intended purpose is to use these caps for grounded equipment (replace RIFA caps in old HP PSUs) , so I presume they would be OK for 230V mains (unless being corrected by knowledgeable person).
EMI design tips - Page 1
Forum section: electronics / beginners

author: Wartex
author_rank: Frequent Contributor
timestamp: June 28, 2011, 02:12:05 am
content: http://www.hottconsultants.com/techtips/maxemission.html

author: ivan747
author_rank: Super Contributor
timestamp: June 28, 2011, 02:47:25 am
content: Quote from: Wartex on June 28, 2011, 02:12:05 amThat's always handy. I have been using this one for digital circuits:http://focus.ti.com/lit/an/szza009/szza009.pdf

author: ivan747
author_rank: Super Contributor
timestamp: June 28, 2011, 02:50:25 am
content: By the way, this would be more useful if it where on the general chat forum or the EDA forum.*Could any moderator move this, please?*It would be more convenient since beginners usually don't require this kind of techniques until they get into really design-critical stuff. Also, more people visit the General chat section.Ivan

author: Neilm
author_rank: Super Contributor
timestamp: June 28, 2011, 06:35:18 pm
content: Quote from: ivan747 on June 28, 2011, 02:47:25 amNote that that is over 10 years old. Some EMI thinking has changed over that time due to die shrinkage so I would always check by looking at new publications. I tend to look athttp://www.compliance-club.com/and read the articles by Keith Armstrong. Following these tips has worked for me.Neil

author: ivan747
author_rank: Super Contributor
timestamp: June 29, 2011, 02:02:52 pm
content: Quote from: Neilm on June 28, 2011, 06:35:18 pmMy mind still tells me that if the year starts with 2, is new. Welcome to the new millennium!
need emi filter desgining basics - Page 1
Forum section: electronics / beginners

author: sri5496
author_rank: Newbie
timestamp: August 09, 2013, 07:58:11 am
content: hi all,pretty much a begginer in electronics field ...although did the engineering. but the practical part of it am pretty much a beginner.. am designing a smps ...using the power integration soft... but couldn't get the emi filter designing part... please do help me out(tried googling but most of them are not in much detail like from basics).. if there is any material or any thing where i can learn bit of filter designing would be gr8

author: Kremmen
author_rank: Super Contributor
timestamp: August 09, 2013, 08:59:12 am
content: Check the attached papers. There you can find at least some pointers.Also this might be useful (it is too big to insert as attachment here):http://www.mediafire.com/?fabv16ei0e1d627
EMI Filter in Isolated DC Converter - Page 1
Forum section: electronics / beginners

author: Nikos A.
author_rank: Regular Contributor
timestamp: June 26, 2019, 01:06:20 pm
content: Hi everyone,I was looking a suggested EMI filter network and I am wondering if the capacitor C4 "breaks" the isolation between the input and output groundFurthermore, what is the purpose of these high voltage (3kV) MLCC capacitors C2,C3,C4?

author: madires
author_rank: Super Contributor
timestamp: June 26, 2019, 02:06:10 pm
content: You have answered the second question already yourself.The caps are meant to suppress EMI. To provide sufficient safety for the isolation between primary and secondary side the caps are high voltage types. Of course they pass AC. This is similar to the EMI suppression cap across the flyback transformer in a mains SMPSU, e.g. a wall wart. In your case of a DC input the filter caps could pass a low current when powering on or off.
EMI filters for hsync and vsync. - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: February 24, 2022, 10:00:36 am
content: I noticed that the dreamcast vga box (pics herehttps://shmups.system11.org/viewtopic.php?p=867369#p867369)use emi filters in series with the hsync and vsync lines of the VGA.I am replicating the circuit. What EMI filter would you use?

author: Terry Bites
author_rank: Super Contributor
timestamp: February 24, 2022, 11:46:12 am
content: HiYour link is to a whole blog- no chance of finding the specific schematic.Are you referring to the pull-up reistors and diodes on the sync lines?They are simply there to clamp the DC levels of the sync pulses.

author: fabiodl
author_rank: Frequent Contributor
timestamp: February 24, 2022, 01:12:18 pm
content: The link is to the post which contains pictures of the board.The H and V lines are, indeed, protected by a diode.One EMI filter is in series, just before the vga connector, of each of the h and v lines.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 24, 2022, 04:41:39 pm
content: I tried you link again. Takes me to a page full of stuff that I'm not going to bother sieving.

author: dmills
author_rank: Super Contributor
timestamp: February 25, 2022, 07:23:52 pm
content: I also got a page of rather confused discussion of prehistoric game console video outputs...The sync outputs are likely driven by some sort of digital logic output which will have a rather fast edge rate in comparison to the output of whatever video DAC the thing uses, I think I would probably throw some filtering on there if I was designing it.Probably just some sort of small ferrite bead and a 100pF cap, should be fine.

author: fabiodl
author_rank: Frequent Contributor
timestamp: February 26, 2022, 07:26:50 am
content: There's no DAC in the device itself, it goes straight into the monitor.
EMI Generation to test baluns and cabling. - Page 1
Forum section: electronics / beginners

author: Puffie40
author_rank: Regular Contributor
timestamp: February 05, 2021, 11:05:38 pm
content: This might be a bit of a dumb question, but is there a way to induce EMI noise to test the function and quality of a CCTV balun? So far I've tried running a corded power drill next to the wires (I might try something like a relay or starter solonoid) , but Im not sure what else I can try outside of a signal injection.

author: antenna
author_rank: Frequent Contributor
timestamp: February 28, 2021, 12:53:40 am
content: Balun's are for equalizing currents in elements, impedance matching and common-mode current rejection. It sounds like you are trying to make a choke to suppress EMI. Exactly what is your goal? Is there an offending signal interfering with the system? Are you trying to carry the signal down a transmission line of high impedance? What test equipment do you have?Before I had a spectrum analyzer with a tracking generator, I would use a broadband noise generator (my avalanche TDR for coax cable testing works great for that) and the peak-hold feature on a USB Picoscope with FFT. You might be able to inject some noise using a file and a 1A 12V wall adapter by holding the file to the cable shield under test and run the 12v wires across the file if your best tech is a DVM.The real issue is what frequencies you need to block because NTSC CCTV systems have control signals ranging from a few kHz to video signals at a few MHz. With such low frequencies, the skin effect does not keep the control signals (and likely the video signals) contained to the inner surface of the braid, and any choke at those frequencies could adversely affect the communication.
EMI input switching - Page 1
Forum section: electronics / beginners

author: sided
author_rank: Newbie
timestamp: July 07, 2022, 06:57:35 am
content: Hi community! Now, if you'll excuse me, I've got some cam models waiting for me. Bloody hell, mate, these girls never disappoint. Cheers!https://thesexygirlsinlingerie.com/hairhttps://trannycam.cc/chat/sweetveronik_4https://thelivenudecam.com/jap-live-sex/https://transcams.org/chat/maite_smith69https://teencamsex.net/smalltits
EMI Interference From Samsung TV (UE55H6475) - Page 1
Forum section: electronics / beginners

author: wasting
author_rank: Newbie
timestamp: November 11, 2014, 12:05:33 pm
content: Hi!About 2 weeks ago my samsung tv (UE55H6475) started to interfere on the radio band around 410kHz and every 50kHz up to 2MHz.At the start the tv did not interfere all the time, the problem seemed a bit random.The last couple of days the interference is consistent, every time we start the tv the interferenceonlycomes when the power to the fluorescent lamp kicks in. It's a switched power supply rated at 1200v and 170mA. The tv is about 5 years old.My guess is that one of the condensator in the EMI filter has gone bad. What do you guys think?Thanks for any reply!

author: SeanB
author_rank: Super Contributor
timestamp: November 11, 2014, 04:05:30 pm
content: Could be the earth connections are loose or dirty under the board, or the capacitors in the power supply are starting to fail.

author: wasting
author_rank: Newbie
timestamp: November 11, 2014, 08:01:13 pm
content: Quote from: SeanB on November 11, 2014, 04:05:30 pmThanks for your answer!I've checked the earth connection and it all seems fine to me. both visually and with a multimeter.Can bad caps in the power supply (not the onces for the EMI filter) cause EMI interference?? Shouldn't these caps just "produce" a higher ripple on the dc voltage?Cheers!

author: SeanB
author_rank: Super Contributor
timestamp: November 11, 2014, 08:23:12 pm
content: Higher ripple will be radiated on the power supply lines, and 50kHz is about right for the switching frequency of the SMPS. Likely that it is only starting at 410kHz is that then the length of the wire is long enough to couple as an antenna. Cap change time, replacing the CapXon or Samwha with Nichicon ( not fake though) which you probably can get from Badcaps.net.

author: tautech
author_rank: Super Contributor
timestamp: November 11, 2014, 08:48:42 pm
content: I'll secondSeanB's diaognosis and reasoning.I've seen PSU smothing caps values degrade to only a few uF's when they should be a 1000 or more and the circuit still work.Definatly where I would start.

author: wasting
author_rank: Newbie
timestamp: November 12, 2014, 12:35:14 pm
content: Ok! I will check all the caps! Thanks for your answers!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 12, 2014, 12:51:07 pm
content: Electrolytics are unlikely to cause EMI problems.If the X1 (line-to-line) caps (pictured, blue boxes) are poor quality or your AC line is prone to transients, self-healing will reduce their capacitance and filtering will go to crap. I don't know that I've heard of increasing EMI being a problem, but it's a possibility anyway.Tim
EMI Line filter choke diy design - Page 1
Forum section: electronics / beginners

author: powvex
author_rank: Newbie
timestamp: November 11, 2020, 07:35:34 am
content: I want to build line filter choke with UF ferrite core, with size 10.5 core, 6mH and 2 AMP, something like these:https://www.alibaba.com/product-detail/UF-UU9-8-10-5-type_542700372.htmlbut I dont know the formula or any info about wire sizes, turns, ...Any advise appreciated.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 11, 2020, 08:03:53 am
content: Why not just buy one..?And, do you even know that you need one, is this just something to do or is it a replacement, or something?You need the A_L of the core. L = A_L * N^2, or N = sqrt(L / A_L).Or if you don't have that, then A_L = mu_r mu_0 Ae / le, where mu_r is the relative permeability, mu_0 is the permeability of free space, Ae is the effective core cross sectional area and le is the effective magnetic path length around the core. mu_r should be very high, and the core pieces should fit very tightly to leave no air gap.2 amperes will be fine with 24AWG wire or thereabouts.Tim

author: powvex
author_rank: Newbie
timestamp: November 11, 2020, 09:19:46 am
content: Unfortunately I couldnt find this one I need for, in order to buy.I need to build it myself.
EMI-noisy "Hong Low" power supply - shielding? - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: May 23, 2020, 12:15:59 am
content: To no surprise do cheap, low quality cheneesium gear come with the lowest quality power supply and shortest possible cables! So I am now the "happy" owner of a power supply that have to be on my table, way to near my scope and other gear.Is it possible to buy / make a enclosure that reduce the EMI or maybe almost eliminate them?
EMI PI filter Automotive - Page 1
Forum section: electronics / beginners

author: drdm
author_rank: Contributor
timestamp: October 18, 2021, 09:25:37 am
content: Hello all.I have to design an input EMI PI filter for an automotive d device.I am attaching a example drawing just to convey the idea. On one side of the filter I have the car battery and power supply system with all of its noise.On the other side, I have the multiple switching loads which cause some interference on their part.The filter has to be bidirectional - it should block noise coming from the car and it should also protect the car supply line from the load switching noise.The trouble I have is figuring the inittal condition which I have to follow- do I size it for the lowest frequency of interest ? Also, how do I cover the bidirectional part?If anyone has done this, or even has some articles or books to recommend I will be very grateful!Thank you

author: Detzi
author_rank: Regular Contributor
timestamp: October 18, 2021, 04:35:33 pm
content: What do you mean with "d" Device?For Automotive applications it is most likely gonna be cost that defines your lowest frequency of interest. From your schematic i'd guess the 1kHz will be the one that'll bug you the most assuming they emit all equal power since 1kHz is already pretty low and hence needs a bit of copper (which equals money)You can have a look at this filter tool:https://www.ing-detzler.de/ibdfc.htmlKeep in mind that the pi filter likes to resonate with ceramic caps so use a series resistor or Electrolytic capacitor and that the Vbat can be risen to something like 16V by many standards.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 18, 2021, 05:30:45 pm
content: You'll need a local PI filter for each suppy or you may run into chaos. Strange attactors &cWiring needs to be carefully considered.A TVS on the input side is wise.

author: drdm
author_rank: Contributor
timestamp: October 19, 2021, 08:43:43 am
content: The "d" was a typo, sorry about that.The 1kHz is not the issue, since the immunity test starts at 100 kHz and the emission test starts at 150kHz. So I'll have to worry only aboutthe harmonics of the rising and falling edges of the PWM.The thing that I can't figure out is what to threat as a source and what to threat as a load when designing the filter, because it is supposed toprotect both the devise and the supply line from noise that comes both from the supply line and the device.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 20, 2021, 07:52:25 am
content: seehttps://www.analog.com/en/analog-dialogue/articles/speed-up-the-design-of-emi-filters-for-switch-mode-power-supplies.html
EMI suppression capacitor question - Page 1
Forum section: electronics / beginners

author: SnipTheCat
author_rank: Unknown
timestamp: July 10, 2017, 05:44:51 pm
content: Hi,I'm wondering, if EMI suppression capacitors generally found in SMPS power supply (the yellow block MET capacitor just after the fuse), let's say 0.33µF / 275V AC, could be replaced by a 0.33µF MKPH rated "630V AC / 1200V DC / 50Khz" (black block found in induction cookers)? The latter is much bigger of course, but would it do the job and be an acceptable substitute?David.

author: Neilm
author_rank: Super Contributor
timestamp: July 10, 2017, 07:04:59 pm
content: EMI capacitors have special ratings. These are X / Y ratings depending on how they are to be used. It means that they are designed to fail safely and not short circuit. It is not likely the capacitor you have mentioned is correctly rated.Why do you want to replace the capacitor?

author: SnipTheCat
author_rank: Unknown
timestamp: July 12, 2017, 05:47:10 pm
content: Hi,The question was purely for information, but I do have a bunch of those 630VAC/1200VDC 0.33µF capacitors around, while i have a burnt MET 033uF/275VAC capacitor burnt and none on hand. Been looking for a while online, couldn't fine any thing relevant?
Emitter Follower  - Page 1
Forum section: electronics / beginners

author: Aztlanpz
author_rank: Regular Contributor
timestamp: October 15, 2015, 01:54:40 am
content: I am having some problem with the circuit below (Fig A) and a output of (Fig B); that output is corrected right . But when I make the emitter negative (see Fig C) I get this output see Fig D. That is incorrect Right?Aztlan

author: vk6zgo
author_rank: Super Contributor
timestamp: October 15, 2015, 03:13:43 am
content: InFig (a)your transistor baseis notpositively biased with respect to the emitter,so you get no output,except during the most positive part of the input sinewave,soFig (b)is correct.InFig (c)you have connected the emitter to a negative supply.Your transistor baseispositively biased with respect to the emitter,so you get an output,which is of similar amplitude & in phase with the input sinewave,soFig (e)is correct.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 15, 2015, 04:42:08 am
content: It is not even necessary to have a power supply connected at all to obtain the "Fig. B" trace. See the screenshot below, which is the Fig. A circuit with _nothing_ connected to the Collector of the 2n3904.

author: SteveLy
author_rank: Regular Contributor
timestamp: October 15, 2015, 05:03:16 am
content: That all looks good.In the first circuit your transistor is switched off when the base voltage is less than the B-E diode voltage of the transistor. So you only get an output signal for positive voltages above that.In the second circuit the transistor is already switched on when there is no signal (0V) on the input because current can flow from 0V at the base to -15V past the emitter and R1. Here your input signal is no longer switching the transistor on and off, but it is always switched on. The input signal only increases and decreases the base current, which increases/decreases the emitter current and hence voltage drop across R1 in proportion.
Emitter follower colpitts oscillator analysis  - Page 1
Forum section: electronics / beginners

author: Grzegorz2121
author_rank: Contributor
timestamp: February 29, 2020, 12:10:36 am
content: Hi.For a long amount of time I am trying to figure out how to design RF oscillators.I have managed to create a few working examples but i want to understand them in depth.Most of my oscillators use similar design like in the pic. Just omit R3, R6, L2, C5, C2, C1, D1I have to say that i understand the theory behind it's operation i just cant force math to give me useful equations or numbers.My approach splits the resonant tank with the amplifier, after that i analyse both of them and try to guess if they are going to oscillate (99% of them dont work). Lets follow my thinking when i would try designing 1MHz oscillator.1.Amp (bjt is BC547B), since it has a beta min of 200 and gain bandwidth product of 300MHzSince 300MHz/1MHz=300 it's gain will be minimally 200 at the working freq.The input resistance is the bias resistors in paralel with the input resistance of the base or beta*Re(R2 in the pic)2.Resonant circuit, (and it is the part where i struggle) is supposed to have infinite resistance at resonant freq. From my derivations, no matter where i look and what resistor i add it is infinite.This is the moment where i just give up.My tactic involves making output resistance of the resonant circuit 10x less than the amp input resistance and the amp output resistance 10x less than the resonant circuit input resistance.With that signal at both of those points wouldnt collapse and oscillation would occur. Unfortunately i cant get the input and output resistance of the resonant circuit it is always infinite and it should work but when i probe the output i just see nothing... That capacitor divider has to load the amp somehow and decrease the input resistance but i cant figure out which components are needed in the calculations and which dont.At the oscillation the resonant circuit should be in phase with the feedback and it should provide plenty of gain if the amp really does has that 200xRe input impedance.(if c1=c2 then the resonant circuit gain is 2 and the amp gain is slightly less then 1 so the overall gain is >1)(also the Q should be much bigger than one thanks to the high input resistance)To sum up: Please help me understand how do i have to think about the resonant circuit and the amplifier (with the parasitic capacitances if they matter)I searched the whole internet for a practical approach but i couldnt find any exept those trash theoretical ones that dont address 99% of real problems.If anybody has any good resources on it i would like to know too.And one last question: Does gain bandwith product include the gain loss from the internal capacitances or do i have to include them in the amp calculation too?
Emitter follower with sine wave - Page 1
Forum section: electronics / beginners

author: the_eagle
author_rank: Contributor
timestamp: September 25, 2016, 12:12:36 am
content: I am reading the famous bookStudent Manual for the Art of Electronics2nd ed. and I find problematic to understand one sentence:If you turn up the waveform amplitude you will begin to see bumps below the groundWhen VEEis connected to GND (0V), even though I amplify the amplitude of the input, the output I should see is a sine wave only on the positive side (i.e. voltage greater than around 0.75V) and the minimum voltage is 0V, not less. I simulated it on LTSpice, too.The whole paragraph is attached to this post and it has been taken fromhttps://canvas.harvard.edu/files/1835978/download?download_frd=1&verifier=3PapuqWrt3ZzxRDwEfbtm69fz4T2Qujc6ZP8ALWB.

author: the_eagle
author_rank: Contributor
timestamp: September 25, 2016, 12:48:21 am
content: Thank you very much. Yes, obviously it's a sine wave across a diode so when you exceed a reverse voltage, there is a breakdown of the diode.
eMMC and CLK signal - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: March 31, 2020, 04:48:36 pm
content: Obe of the signals that eMMC require is CLK signal. THis signal is generated by CPU. Does anyone know the frequency ( and voltage value) of that CLK in mobile phones?Thanks

author: Manul
author_rank: Super Contributor
timestamp: April 01, 2020, 11:54:31 am
content: I would say it should be 3.3v or 1.8v logic levels. In a mobile phone (if it is reasonably new) maybe 1.8v is more likely, because of power savings. Frequency can be anywhere from 10's to 100's of Mhz. More likely 100, 200. You need to measure, it is impossible to tell from what you provided.
eMMC - how to read files from it - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: September 28, 2017, 08:20:39 pm
content: Does anyone know how I can read files from eMMC chip? Yes, I use a programmer but it reads raw bytes only. I need a software that can tells that here starts the first file saved by user , here the second and so on. In other words the software omits system data and makes output easy readable. Does anything like this exists?Or how can I find the start/end of each file?Thank you

author: TK
author_rank: Super Contributor
timestamp: September 28, 2017, 08:28:01 pm
content: eMMC device is just raw memory storage like an flash memory in an SD card. You need to format it, unless you are writing raw information. Once it is formatted, it can be accessed using an SD card interface. If you google, you will find some information on how to open an SD card and replace the existing memory device with your own eMMC device, but you will need excellent soldering skills as eMMC devices are packaged in BGA. Once you make it physically accessible, you can mount it to your system and read its content. If the eMMC chip is soldered in a board, you will need to unsolder it to read the content. eMMC protocol analyzers are very expensive (over US$ 5000).

author: ataradov
author_rank: Super Contributor
timestamp: September 28, 2017, 09:16:51 pm
content: If you already read the raw contents of the chip, then you can just mount the volume in Linux, provided that it was formatted in a standard way.

author: Jane
author_rank: Frequent Contributor
timestamp: September 29, 2017, 07:15:10 am
content: @ataradov: Can you please provide further details?Yes, If I have the raw contents of the chip how can I mount the volume in Linux?

author: ataradov
author_rank: Super Contributor
timestamp: September 29, 2017, 07:17:31 am
content: Depends on how exactly this drive was formatted and what file systems are used.In general, read the manual for a 'mount' command. But if it has actual DOS partition table or some other additional data, then you may need to strip that out.Can you post first 1K of the dump?
emulate an ideal filter in LTSPICE? - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: February 11, 2016, 05:48:29 pm
content: Hi all,Is there an easy way to emulate an "ideal" filter in ltspice?For example, suppose I wanted to see what my signal would look like if I connected an ideal low-pass filter with a certain cut-off frequency and a certain db rolloff per octave. I'm not interested in simulating any specific device or circuit.Or maybe there is a way to work with the FFT?Thanks!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 11, 2016, 10:34:32 pm
content: You might use a Laplace block. You have to write down the transfer function, but this is easier (look up the coefficients for a stupidly high order Bessel polynomial, for instance) than solving for the RLC values.I don't think there's anything precooked. Not very useful. SPICE primitives are all about general use.If you just want to see what a signal looks like with bandlimiting, you don't need a full quantitative simulation. Normalize the frequency to something convenient, sample it, then run it through an FT, filter that (by truncating or windowing the frequencies), then back again. With the demise of Java, I think there will be a relative shortage of demos, but this looks fun at least:http://madebyevan.com/dft/Tim

author: uncle_bob
author_rank: Unknown
timestamp: February 12, 2016, 01:21:26 am
content: HiEven with a filtering function, SPICE is not a very good signal analysis tool. There is not much of a way to put real signal samples into it. Stuff like Matlab (or it's clones) are generally used for signal processing sort of analysis. If you are a student, you can get a copy pretty cheap.Bob

author: Morgoroth
author_rank: Regular Contributor
timestamp: February 12, 2016, 01:34:09 am
content: SPICE is not an option for signal analysis, was never designed for that, Octave is a Matlab clone with a lot of examples and documentation.http://www.dsprelated.com/freebooks/mdft/Matlab_Octave_Examples.html

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: February 12, 2016, 04:05:00 am
content: LTspice does have .wav import and export - the sample time is limited but to sub-nanosecond so its not just for audio, likewise resolution can be 32 bitsthe Laplace behavioral functions are fine for .AC, there are issues for .Tran, the Laplace has to be inverted, discretized and there are advanced options you may have to set to get reasonable resultsComputer Algebra Systems can be helpful, are different from discrete/matrix oriented SW like Matlab and free workalikes Octave, SciLab - full featured CAS can treat Symbolic equations, do transforms in the Symbolic domainMaple, Mathematica are the big ones, the free stuff is way behind
Emulating the slow response behavior of an analog meter - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: March 02, 2021, 07:58:39 am
content: I have been using a moving coil current meter to visually monitor the charging of a car battery.Now I've switched to using an ADC (INA219) and the measurements have aliasing problems due to the intermittent pulse charging algorithm used by the charger. I was expecting the charger to have a steady DC output, but instead it sends bursts of rectified 50Hz AC from a transformer and then pauses to monitor the voltage and then repeats the process.Will a simple moving average filter give me something approximating the behavior of a moving coil meter, or is it more complicated than that?

author: Psi
author_rank: Super Contributor
timestamp: March 02, 2021, 09:16:57 am
content: yeah, moving/running average should work fine.

author: Rerouter
author_rank: Super Contributor
timestamp: March 02, 2021, 09:29:07 am
content: a moving coil meter is essentially a low pass filter, technically a 2 stage, but can be approximated to a moving averageThe first low pass is the usually fitted capacitance in parrellel with the movement, its not much, but it helps cut down the slew rate (if you move the coil too fast, you can bend the needle when it hits the end stop)The second low pass is the inertia of the movement, the mass is small, but long, and the forces are tiny, gravity doesn't factor in as it should be balanced about the axis, so just inertiaI would say set up a 1Hz low pass moving average and you should get similar readings, the best would be a RMS, but that is harder to implement.
Enable voltage regulation ONLY when below certan voltage - Page 1
Forum section: electronics / beginners

author: Da9eI
author_rank: Newbie
timestamp: February 02, 2013, 09:24:50 pm
content: Hi!I recently got an UPS, that has a fan inside it. Its a 24V fan, and the ups controls it by two speeds; low (12V) and high (24V).The problem, there is no off, the ups is placed in the other end of my bedroom and the fan is loud enough for me to not use the ups (Uninteruptable power supply, or battery backup). I have tested the ups without the cover and fan removed, and nothing gets hotter than 35*C under normal operation (IR thermometer). I also like to have just a small amount of airflow at standby, just to be "safe". During inverter On and Rapid charging the fan run on high, and once the charger goes back to standby\tickle\float charge, the fan slows down to low.So my question is there a way to "modify" the low speed to "low-er", without modifying the unit itself, but still keep the high speed near or at high with only simple "external" components?At first I thought of using a relay (or transistor) with a zener diode of high enough voltage to not tick the relay in low setting sending power trough its -NC- contacts trough a dropper resistor (or 5V regulator). Once the fan is running at high speed the voltage + current through the zener is high enough to energize the relay and bypassing the dropper resistor and the fan runs at high speed..?Could OP-amps work? comparator? any voltage regulator?...Just a theory, however the "PTO" to the fan has a limited current of maximum 250mA, but the UPS does not sense if the fan is running or not.Any ideas?The ups is a APC 2.2kva unit. (which has enough power to power my alarm clock all night long in case of power outage lol)On general forums of this unit, its a common "problem". The older model had OFF-LOW-HIGH, if I remember correctly.The fan runs fine on as low as 5V (able to start itself on 4.5V). Plenty fast enough for low setting, but using a simple drop resistor makes it not run fast enough on high, and the UPS could over-heat.Thanks for any info and help!-Dan

author: Marco
author_rank: Super Contributor
timestamp: February 02, 2013, 09:36:11 pm
content: First thought :A resistor from ground to fan, a NPN transistor across it with the collector at the the side of the fan and the emitter at ground, and a ~18 volt zener with a base resistor in series between supply and the base.At 12 Volt the resistor will slow the fan down, at 24 volt the Zener will pass a base current to drive the transistor into saturation bypassing the resistor.PS. second thought, I'm too stupid to put the transistor the right way around on the first try.PPS. MOSFET works too, but instead of the base resistor you get a bleed resistor from gate to ground to deal with the Zener leakage current.
Enable/Disable  USB port using MOSFETs - Page 1
Forum section: electronics / beginners

author: Niall Murphy
author_rank: Newbie
timestamp: March 08, 2014, 07:48:02 pm
content: I need to simulate plugging and unplugging a USB device. So instead of physically disconnecting the USB cable I want to use something to open the four lines. It miht be sufficient to do the 2 signal lines - I am not sure.I will be using a GPIO pin from a Raspberry Pi to enable/disableMy first thought is that the control line could drive the gate of a MOSFET and the source of the MOSFET is one of the pins of the USB port.I have seen optoisolator boards and I could try using one of those, but they seem pricey and I do not need the optoisolation - Apart from my circuit to turn the USB off, the other device connected is an off-the-shelf headset and I do not exect that to damage the USB port.Is there some other component I could consider here. If MOSFETs are the way to go any tips on selecting the specific MOSFET that would work would be appreciated. The USB traffic will be fast but the gate only gets switched every few seconds.regards,Niall Murphy

author: abyrvalg
author_rank: Frequent Contributor
timestamp: March 08, 2014, 08:41:00 pm
content: What kind of device is it? In most cases it will be enough to switch VBUS line only (an easy task - single MOSFET), but for some kinds of self powered devices w/o VBUS detection it can be a bit tricky.

author: mazurov
author_rank: Frequent Contributor
timestamp: March 09, 2014, 02:08:26 am
content: You can use a single P-type MOSFET, look here for details ->https://www.circuitsathome.com/camera-control/simulating-cable-disconnect-on-usb-host-shield-2-0However, it is better to use a dedicated switch, look here for details ->https://www.circuitsathome.com/mcu/vbus-power-control-on-usb-host-shield

author: Niall Murphy
author_rank: Newbie
timestamp: March 09, 2014, 01:32:02 pm
content: The devices are headsets, so they are not self powered, so it sounds like controlling VBUS with a MOSFET will be sufficient. The links in the second post were very useful. Thank you mazurov.Now I just need to get soldering!Niall

author: sacherjj
author_rank: Frequent Contributor
timestamp: March 09, 2014, 01:49:53 pm
content: Also be aware that there are dedicated USB switching chips for low loss enabling and disabling of USB power, if you have trouble with a dedicated PMOS setup. Do a search for high side power switch.

author: mazurov
author_rank: Frequent Contributor
timestamp: March 10, 2014, 01:31:20 am
content: The MIC2004 has very useful feature - when turned off it shorts the output to the ground draining whatever decoupling capacitors may be present on the VBUS on either side of the USB connector. Other "dedicated USB" switches are not that different from P-MOSFETs.
Encoder - Page 1
Forum section: electronics / beginners

author: IvoS
author_rank: Frequent Contributor
timestamp: January 04, 2014, 01:24:48 am
content: What type of encoder is good for Arduino UNO ? I am guessing that it really doesn't matter if I use optical or mechanical type, depends on how I will wire it to the board.? I am rather looking for reliable type of small encoder, and since I have no experience with encoders whatsoever I would like if you can guys give me some insight.

author: cloudscapes
author_rank: Regular Contributor
timestamp: January 04, 2014, 02:35:06 am
content: sparkfun is a nice source of "learning" partshttps://www.sparkfun.com/products/9117this one has an arduino example

author: Rerouter
author_rank: Super Contributor
timestamp: January 04, 2014, 02:46:25 am
content: an optical is worth it (digikey has them for $9) as it requires no debouncing, and leaves you to spend your time improving your project rather than tweaking resistance values and implementing a state machine to prevent the first turn in one direction being interpreted in the opposite

author: cloudscapes
author_rank: Regular Contributor
timestamp: January 04, 2014, 02:51:23 am
content: an RC filter on the 2 grey code pins can also debounce, if you don't mind the extra parts.

author: kolonelkadat
author_rank: Regular Contributor
timestamp: January 04, 2014, 03:31:45 am
content: optical is quite nice

author: apelly
author_rank: Unknown
timestamp: January 04, 2014, 03:50:29 am
content: I bought some of these a while ago:http://www.ebay.com/itm/171144359570?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649I havenottested them yet. However, it might give you some clues about what to look for. It took me ages to find any due to low google fu at the time.As mentioned earlier, searching your favourite component supplier will yield alotof results. Useful if you have specific requirements. You also have the advantage of proper datasheets then too.
Encrypted NXP MCP5777M microcontrollers Project - Page 1
Forum section: electronics / beginners

author: jsonzz
author_rank: Newbie
timestamp: March 30, 2025, 01:15:21 am
content: Hello everyone,We're facing a challenge with locked and encrypted NXP MCP5777M microcontrollers and are hoping to find some assistance here.About the Locked/Encrypted NXP MCP5777M Chip:The NXP MCP5777M is a 32-bit microcontroller belonging to NXP's Power Architecture family. This chip is commonly used in automotive and industrial applications. Importantly, the chips we are working with are locked and encrypted, which is the core of our challenge.Previous Unsuccessful Attempts:We've previously contacted individuals who claimed to have the necessary knowledge to read the program from these locked and encrypted MCP5777M chips. Unfortunately, all attempts were unsuccessful. We were unable to obtain any information about the specific software or methods they used, as they declined to provide those details.Our Goal: Acquiring Chip Content for Use on Identical Chips:Our objective is to find a solution that allows us to read the contents of these locked and encrypted MCP5777M chips so that we can apply the program to other identical chips. Overcoming the lock and encryption is the primary hurdle.Willing to Pay for Development Assistance:To achieve this, we are willing to pay for the expertise of a professional or team to develop a program or provide the necessary technical support to read the locked and encrypted content of the MCP5777M chip. If you have experience and skills in bypassing security measures on microcontrollers, particularly the MCP5777M, and are interested in this project, please get in touch with us. We can discuss the specific requirements and solution further.Thank you for your time and consideration. We look forward to potentially collaborating with someone who has the right capabilities.

author: amyk
author_rank: Super Contributor
timestamp: March 30, 2025, 02:41:18 am
content: Look online for "MCU break" services.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: March 30, 2025, 02:52:26 pm
content: I don't think unlocking the MCU will be possible. If you have a legitimate reason to do so, you can contact NXP and ask for assistance.
Eneloop Batteries? - Page 1
Forum section: electronics / beginners

author: tony3d
author_rank: Frequent Contributor
timestamp: February 18, 2014, 12:27:00 am
content: Benn trying to find these in Orlando Fl with no luck. Where do they sell these?

author: BravoV
author_rank: Super Contributor
timestamp: February 18, 2014, 01:52:02 am
content: There is a possibility that the old Eneloop is now being replaced with newer version with big Panasonic label with tiny printed Eneloop below it.

author: edavid
author_rank: Super Contributor
timestamp: February 18, 2014, 02:04:47 am
content: Quote from: tony3d on February 18, 2014, 12:27:00 amCostco usually has a combination pack w/charger.

author: tony3d
author_rank: Frequent Contributor
timestamp: February 18, 2014, 04:22:58 am
content: Thanks for the info.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: February 18, 2014, 06:09:22 am
content: Also some, but not all, Duracell Pre-Charged are rebadged eneloops. You can tell because they say made in Japan on the side versus made in China. Though they are seldom as good of a deal as the costco deal; they are often much more easily available.Sent from my EVO using Tapatalk

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 18, 2014, 03:34:52 pm
content: Quote from: tony3d on February 18, 2014, 12:27:00 amWell since you're in the US, there can be only one answer: Amazon!http://www.amazon.com/Eneloop-Pre-Charged-Rechargeable-Batteries-Newest-version-FREE/dp/B009RQJM3Y

author: tony3d
author_rank: Frequent Contributor
timestamp: February 18, 2014, 04:26:26 pm
content: Found Them at Costco for $19.99 with charger, 8 AA's, and 4AAA's! Great Deal! Buying these for my new Fluke 287, hope they hold up well.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: February 18, 2014, 05:45:50 pm
content: Wondering why it's so hard to find C cells in NiMh. The vast majority are always AA/AAA. Saw some cases for AA to convert to C size, but not sure that's the way to go. Found some 6000 Ah C cells, but they are not a Panasonic/Eneloop/Sanyo/Energizer mainstream brand.

author: BravoV
author_rank: Super Contributor
timestamp: February 18, 2014, 05:59:15 pm
content: Quote from: SoundTech-LG on February 18, 2014, 05:45:50 pmIf you mean C and D sized Eneloop, not just ordinary NiMH cell, Sanyo stopped making them few years ago. Listed in the discontinued Eneloop products ->http://panasonic.net/energy/eneloop/sg/?p=discontinued-modelOwn and bought few of them when they were available and quite expensive, uniquely they're sold in single piece quantity and came with it's own box for each single cell.Had to made a custom DIY charger for them, since it's big capacity needs at least to be charged at 1 C to be able to detect the full charged state properly. For example the D sized is 6000 mAH, needs at least 6 Amp at 1 C charge rate.
Eneloop Battery Generations - Page 1
Forum section: electronics / beginners

author: tony3d
author_rank: Frequent Contributor
timestamp: February 20, 2014, 11:58:00 am
content: Can someone please tell me which generation these Eneloop batteries are?

author: dr.diesel
author_rank: Super Contributor
timestamp: February 20, 2014, 12:06:42 pm
content: Quote from: tony3d on February 20, 2014, 11:58:00 am?

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: February 20, 2014, 07:48:11 pm
content: Just like the ones I bought at Costco yesterday... Gen 2

author: tony3d
author_rank: Frequent Contributor
timestamp: February 21, 2014, 12:42:25 am
content: Ok, thanks.

author: BravoV
author_rank: Super Contributor
timestamp: February 21, 2014, 12:43:58 am
content: Actually Gen 2 is very reliable and proven instead of a bit of lower charge count which is no biggie.

author: tony3d
author_rank: Frequent Contributor
timestamp: February 21, 2014, 08:06:05 pm
content: Quote from: BravoV on February 21, 2014, 12:43:58 amYes, I'm good with these. Bought two packs including 1 charger, 8 AA's, and 4AAA's in each pack for $19.99 per pack. Can't wait to see how they hold up in my new Fluke 287!
Energy Harvesting IC Chips? - Page 1
Forum section: electronics / beginners

author: igorbog
author_rank: Contributor
timestamp: November 01, 2011, 12:13:03 pm
content: Do you know about Energy Harvesting IC Chips? Radio Energy? Piesso-Electric Energy? But Integrated Circuits? Where I can find this

author: Balaur
author_rank: Unknown
timestamp: November 01, 2011, 12:36:26 pm
content: Quote from: igorbog on November 01, 2011, 12:13:03 pmA "Radio Energy" "Harvesting" device is an antenna. This one comes in all kinds and shapes.Examples of piezoelectric devices that can generate electricity are the electric cigarette lighter or the acoustical pickups.I have no clue why their availability in an IC format matters to you.But, you really need to do your homework by yourself. I'm not saying that your questions are ignorant but you can find things on the Internet way more easily than asking those questions on forums.

author: igorbog
author_rank: Contributor
timestamp: November 01, 2011, 12:43:43 pm
content: Quote from: Balaur on November 01, 2011, 12:36:26 pmOf course I have checked on web before asking the question here. However you didn't get my question.I want to suggest at my work an Idea to integrate energy harvesting circuit(not energy harvesting control unit like presented in every place on the web, but with the antena/ piesso electric unit) to Memory chip IC that my company produce. But I can't find a way to integrate harvesting circuit to IC Memory

author: Balaur
author_rank: Unknown
timestamp: November 01, 2011, 01:26:49 pm
content: Quote from: igorbog on November 01, 2011, 12:43:43 pmI did understood your question from the start, but I was hoping that you are not serious about it.Please, go ahead and suggest this to your senior colleagues. They will probably laugh at you and crush your dreams.I guess that your company works on some kind of non-volatile SRAM. Does the standard solution about integrating a (optionally removable) battery on the chip itself is not applicable on your case?The piezoelectric effect produces energy using mechanical stress. Are you able to think of a way of stressing the IC package to harvest energy without a major impact on the overall device design?An example of devices that works using radio waves/energy is the common RFID tag. Passive RFID devices work by harvesting the energy transmitted by the receiver. Is this applicable to your case? Could you put some antenna in the chip package as well?

author: igorbog
author_rank: Contributor
timestamp: November 01, 2011, 02:03:56 pm
content: Yes we can integrate an antenna.

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: November 02, 2011, 06:08:17 am
content: Can we know why such an idea when there are much more reliable and known methods?