Filtering switching noise with ferrite beads and linear regulator - Page 1
Forum section: electronics / projects

author: ramicio
author_rank: Regular Contributor
timestamp: April 29, 2013, 03:05:21 pm
content: I need to take the 12 volt rail from a computer PSU and get 5 volts of clean DC out of it. 500 mA is what it will be seeing. I have been researching this, but I cannot find any examples. How do I choose a ferrite bead? How do I know what value capacitors to put on it? I am going to be using a LM2940 LDO regulator.

author: KJDS
author_rank: Super Contributor
timestamp: April 29, 2013, 03:24:14 pm
content: What frequency is the PSU switching at?

author: ramicio
author_rank: Regular Contributor
timestamp: April 29, 2013, 03:25:12 pm
content: I have no clue, nor do I have the equipment to measure it. It should be a very broad range, since what I am making will outlast the computer it's going into. Let's assume 10 kHz to 100 kHz.

author: free_electron
author_rank: Super Contributor
timestamp: April 29, 2013, 03:49:51 pm
content: I have to build a ladder, but i don't know how long ot needs to be and i also have tools ..You'll have to experiment then....Modern computer psus go up to 500 khz and beyond....But there is not only yhr hf noise. What about the ripple ?I would first filter using a big inductor with an iron core. That will stop a lot of garbage and dampen ripple. Then a big fat capacitor shunted by a few small ones.Then a good linear regulator followed by another output filter.In order to dimension that filter i need more i formation about the load...Is it something that switches ? Something linear ?

author: ramicio
author_rank: Regular Contributor
timestamp: April 29, 2013, 03:55:34 pm
content: I just don't know. I don't have the equipment nor money to experiment building circuit after circuit until I get something that works, and then have it be able to work in another future setup with a different switching frequency.The load is an LED audio spectrum analyzer. All the maker said is that I need something capable of delivering 500 mA. He's very closed about the design and I'm not impressed with the fact that it doesn't have FFT, but some digital potentiometer to act as RC filters to get the frequency bands. The thing's own power supply is faulty and creates random spikes that he says can be fixed by removing that supply and powering it with a linear supply.

author: SeanB
author_rank: Super Contributor
timestamp: April 29, 2013, 05:23:32 pm
content: 5V at 500mA is easily done just using a 7805 on a heatsink, about as big as the ones inside the supply you are using. Filter is a 1R- 2R2 5W series resistor in the 12V line, and a 1000uF 25V capacitor after it. Right at the regulator input and output you have a 100-470n ceramic sisc capacitor, and a 100uF 16V capacitor at the output right near the regulator. This will work well for most loads and will have about the best low cost noise performance. You can use your LM2940 in place of the 7805, just note that the output and input capacitors must be low ESR types, generally most 105C electrolytics will do here.

author: ramicio
author_rank: Regular Contributor
timestamp: April 29, 2013, 05:27:04 pm
content: What is this filter resistor you speak of and how would 5 watts be enough?

author: SeanB
author_rank: Super Contributor
timestamp: April 29, 2013, 05:32:49 pm
content: Big white wirewound ceramic resistor, the common one you see all around you in equipment.Like here

author: ramicio
author_rank: Regular Contributor
timestamp: April 29, 2013, 06:28:12 pm
content: I know what those are, I just wondered how it's a filter and I had no idea what 1R or 2R2 meant. And how would 5 watts be enough?

author: c4757p
author_rank: Super Contributor
timestamp: April 29, 2013, 07:11:26 pm
content: Google "RC filter".1R, 2R2 = 1 ohm, 2.2 ohm.How would 5 wattsnotbe enough? I don't see the problem. P = I2R.

author: SeanB
author_rank: Super Contributor
timestamp: April 29, 2013, 07:18:02 pm
content: RC filter, resistor value is anything between 1 ohm and 2.2 ohms, as they will work without getting too hot with 500mA through them. Will actually handle 1A, but then the resistor will be running at around 100C above ambient. Will drop around 1-4V across it, but then again otherwise you will be dumping this as heat in the regulator itself.

author: Unknown
author_rank: Unknown
timestamp: April 29, 2013, 09:19:33 pm
content: Assuming the noise is switch mode derived, just the use of an iron toroidal-core, with common-mode winding should stop the problem... e.g.http://www.emo.org.tr/ekler/5730ca725508e90_ek.pdf

author: free_electron
author_rank: Super Contributor
timestamp: April 29, 2013, 09:25:56 pm
content: Quote from: ramicio on April 29, 2013, 06:28:12 pmGive it up. This is beyond you.You have :- no money to experiment- no equipment- no tools- no clue what 1r or 2r2 stand for on a resistor- only vague description on what it is you have to doyet you bash a design because 'it doesn't use fft'I suggest you seek a different hobby. Basketweaving is popular these days ...Topics like this make my hair curl...

author: AndyC_772
author_rank: Super Contributor
timestamp: April 29, 2013, 09:36:55 pm
content: I agree completely, this project is the blind leading the blind. Even if you do come up with something that works, it'll be by chance, and probably won't be working for the reason you think it is. You've not even mentioned grounding, which I strongly suspect is at the root of your problem.A PC power supply switches at anything from 50kHz upwards, but that's before you consider by far the most important aspect of the noise which is the RF component of the switching spikes. The true noise bandwidth will extend from a few Hz (coming from the switching jitter and instability in the control loop) up to hundreds of MHz, and no single technique works across that entire range.You need to knowwhatnoise is affecting the circuit,whereit's coming from, andhowit's coupling into the circuit in a way that actually affects its operation. Only then can you determine whether a filtered supply from the PC will even make any difference. Sorry to be blunt, but speculation and guesswork isn't going to solve this one quickly or easily.

author: ramicio
author_rank: Regular Contributor
timestamp: April 29, 2013, 10:05:00 pm
content: Quote from: free_electron on April 29, 2013, 09:25:56 pmHey, don't comment if you have nothing to say. I don't have an oscilloscope, how does that mean I have no tools? Sorry I didn't understand what 1R or 2R2 meant when someone could have just said 2.2 ohms. I've never seen anyone use that terminology before. Yes, I know a capacitor and a resistor are an RC filter, I just didn't glean that because I parsed the sentence as English, not electrician. I'm a hobbyist, not a professional. Why isn't there a middle finger smiley?Everyone else, you've been helpful and patient. Thank you. I'm new to this area of "the hobby." The only information I've found on this was some Jim guy talking about a ferrite bead. vlf3 helped by posting a nice article that gives examples.

author: c4757p
author_rank: Super Contributor
timestamp: April 29, 2013, 10:14:23 pm
content: Quote from: ramicio on April 29, 2013, 10:05:00 pmJust because it's a harsh opinion doesn't mean it's nothing to say.QuoteIn the same way that if you lacked a wrench you could not change a tire with string, chewing gum and wishful thinking. That is the tool for this job.QuotePay more attention. It's quite common. The resistors themselves are likely to be marked that way.QuoteYou know a cap and a resistor form an RC filter, you were told to use a cap and a resistor and even told that it would be a "filter" and you didn't recognize that it's an RC filter?QuoteBecause the correct response to constructive criticism is "Thank you", even if you don't like the answer. Reality is under no obligation to be nice. The only place for "fuck you" is in jest or in response to a complete asshole, and nobody here is joking or appears to be an asshole.

author: ramicio
author_rank: Regular Contributor
timestamp: April 29, 2013, 10:23:28 pm
content: His entire response was that of an asshole's, with his assholish basket weaving BS. His criticism was not constructive, it was "go away because you're too poor to afford this hobby."

author: marshallh
author_rank: Unknown
timestamp: April 29, 2013, 10:29:36 pm
content: I have received verbal whacks upside the head, proper response is to actually address the issues instead of having hurt pride... Suck it up and take the opportunity to teach and better yourself

author: c4757p
author_rank: Super Contributor
timestamp: April 29, 2013, 10:30:31 pm
content: I thought the basket weaving comment was a joke, but either way it doesn't make a difference. Even if it was meant to be an insult, one insult doesn't invalidate everything else somebody says. "Go away because you're poor" wouldn't be very nice, but unfortunately things cost money. You can't do some things without an oscilloscope, and whining that you're too poor for one isn't going to make those things doable without it.

author: TerminalJack505
author_rank: Super Contributor
timestamp: April 29, 2013, 11:24:38 pm
content: Quote from: ramicio on April 29, 2013, 06:28:12 pmI'm guessing this is that "Jim guy" you are referring to:That's the late Jim Williams. You'd do well to following any advice Jim gives regarding electronics. He's very well respected. Here's theapp notehe refers to. At the very least read appendix A.It sounds like you just need to do a little reading on ferrite beads. Manufacturers will always have material to helpmake a saleyou out. Don't know who manufactures ferrite beads? Guess who does: Digikey, Mouser, etc. I bet Digikey even has a Product Training Module on ferrite beads. (Here's one.)All you probably need to worry about is choosing beads that have the proper current handling capability. Basically beads designed for DC power supplies as opposed to bead designed for signals, for example.The only other characteristic you might need to worry about is the ferrite's impedance at 100MHz. I'd just pick one around 200 ohms and be done with it. Put these in your circuit as described by Jim (figure 4 of the app. note) and this will be about the best you can do considering you have no test equipment.

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 02:42:21 am
content: I'll look for a scope at some point. I'm not in a hurry with this project.

author: AndyC_772
author_rank: Super Contributor
timestamp: April 30, 2013, 06:14:49 am
content: Quote from: TerminalJack505 on April 29, 2013, 11:24:38 pmMany ferrite beads are quoted @ 100 MHz, and in many cases the manufacturer's data sheet includes a plot showing the impedance across a much wider frequency range. The proper way to choose one requires knowledge of the noise frequency that actually exists and which is causing the problem - for example, following a trip to an EMC lab.If the product is an audio spectrum analyser, it might be sensitive to audio frequency noise (where no ferrite bead will have any useful effect whatsoever), or it might be affected by much higher frequencies. There's no way to know without experimentation.

author: veryevil
author_rank: Unknown
timestamp: April 30, 2013, 10:05:15 am
content: This may be a silly question but why can you not use the 5V rail on the computer PSU? Why does it have to be the 12V rail?

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 06:28:39 pm
content: Quote from: veryevil on April 30, 2013, 10:05:15 amBecause the circuit needs a clean 5 volts DC. I don't know any way of starting from 5 volts, cleaning it up, and getting 5 volts back out.

author: c4757p
author_rank: Super Contributor
timestamp: April 30, 2013, 06:29:36 pm
content: Quote from: ramicio on April 30, 2013, 06:28:39 pmA giant LC filter? Lots of L, lots of C, and good quality C (bypass with small ceramic types). That's how it was done in the old days. I have an ancient function generator (vacuum tube days, before simple linear regulators) that manages to get nearly perfect DC straight off the rectifier with only two 56uF capacitors, because it has one bigass choke between them.

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 06:33:28 pm
content: Too late. I already ordered the circuit board that will be supplying this power and it's tied to the 12 volt line. This thing already has some kind of LC crap already and it's flawed...causes random spikes on different bands every few seconds.

author: c4757p
author_rank: Super Contributor
timestamp: April 30, 2013, 06:33:53 pm
content: Since huge inductors are hard to come by these days, you can use the primary of a spare mains transformer with the secondary left open. That will easily be upwards of 1H, depending on the transformer.

author: c4757p
author_rank: Super Contributor
timestamp: April 30, 2013, 06:34:48 pm
content: It's not flawed, it's "good enough". Those spikes were OK to the designers so they left them. A well designed LC filter will easily strip those out.

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 06:35:09 pm
content: This is all going into a 5.25" empty CD drive.

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 06:37:04 pm
content: Quote from: c4757p on April 30, 2013, 06:34:48 pmIt's not "good enough." They occur with nothing even being input to it. He even said it's a flaw that he intends to fix in another revision. I've almost had it with this whole project. It would have been nice to know how inaccurate it was before purchasing it.

author: c4757p
author_rank: Super Contributor
timestamp: April 30, 2013, 06:41:16 pm
content: I'm a bit confused - aren't you trying to get the spikes off the rails from a PC power supply? That's what I meant - I thought you were talking about the internal filters in the power supply. If it's the filters on some add-on board that aren't filtering anything, I'd agree, it's probably a poor design. Still, an LC filter is the way to go, you just have to do it right. In fact, it's probably the only thing that can keep up with those spikes - they'll go right through a voltage regulator because they're too fast.

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 06:45:21 pm
content: No, the  spectrum analyzer has a fault in its own power supply that causes spikes to be randomly displayed every few seconds. I am trying to give a clean power supply and bypass its own power supply. I guess I will do an LC filter and then a regulator.

author: c4757p
author_rank: Super Contributor
timestamp: April 30, 2013, 06:49:02 pm
content: Quote from: ramicio on April 30, 2013, 06:45:21 pmOh, that's just awful.Is it at least a separate module and not integrated into the main board? If so, try adding chokes inline with the wires. You might have luck with a common mode choke (both power and ground on the same core).

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 06:52:53 pm
content: It's just a small IC and some capacitors and an inductor. I am just removing them all and feeding it with 5 volts from the supply I am making. As I said, it's too late now to just do some simple choke stuff. A related board I made and ordered has the output tied to the 12 volt line.

author: ramicio
author_rank: Regular Contributor
timestamp: April 30, 2013, 06:58:01 pm
content: I'm noticing these inductors don't have much of a current rating.EDIT: I do have a bunch of these larger common mode chokes around I can pull off of scrap boards.

author: ramicio
author_rank: Regular Contributor
timestamp: May 01, 2013, 12:03:26 am
content: I took some toroidal common mode chokes off a scrapped PSU I have. I tried the small one with a smallish (220µF) capacitor and there are fewer spikes. I'd imagine with the larger choke and a larger capacitor, like 2,200µF or 3,300µF, it should be perfect. I have no idea what the values of the chokes are.

author: c4757p
author_rank: Super Contributor
timestamp: May 01, 2013, 12:11:21 am
content: I don't think a larger capacitor is going to help much. What you need to do is shunt the large capacitor with multiple small, good quality capacitors (I'd say maybe 100pF, 10nF, 100nF ceramic). As for the choke, it's hard to say that a larger one will have a higher value - it could be just a higher current rating. It's really hard to judge the value of an inductor by looking at it - the core material has ahugeeffect. I've got some toroids that will give me as much inductance in two turns as some entire small wound inductors...

author: free_electron
author_rank: Super Contributor
timestamp: May 01, 2013, 12:37:30 am
content: Quote from: ramicio on April 29, 2013, 10:05:00 pmAre you sure ? Using an R and a C one can make a highpass , lowpass bandpass, differentiator or integrator.. depends on how they are connected...Saying an Rc is a filter is like saying 'it's a vehicle'.. ok. but what kind of ? a bike ? a train ? a car ?QuoteOuch. Both Bob and Jim are now preparing to unleash an electronstorm that will wipe out all the data on your harddisk...You say that spectrum analyser thingy shows 'spikes'. you also say its made with an ic and some LED's. LM3914 ?who says the spike comes in through the power supply? if that cable that brings in the signal picks up a spike along the way it may very well come in that way. fidgeting with the power supply doesn't do any good then.the lm3914 needs a high and a low reference. i'm assuming you use gnd as low reference. how do you make high refrence. (please don't say using a potmeter derived from vcc... ) there should at least be a zener or an active regulator there.... with appropriate bypass capacitors.other thing : how do you feed the analog signal in ? is it properly biased. i'm assuming it comes in through a coupling capacitor. did you provide clipping diodes there ? it is possible if a peak is coming in the input couping capacitor gets charged in such a way that on a further change of the input it actually overloads the lm3914... pusing input above vhigh of an lm3914 gives very weird results ....Make a nice metal box , make a nice PCB , use feedthrough cap for power in , followed by a nice choke-capacitor lowpass filter, followed by a 7805 with some ceramic caps around it. make sure the case is grounded to the board ground.Use an input circuit with a lowpass that only lets audio go through , use a shielded cable, maybe a common mode choke there and keep that input line away from noise generators such as the choppers on the motherboard.There. Happy now ? now you have some more constructive criticism. But i stand by my earlier remarks.You are gunning blind for a problem that may not even be there. it's like trying to hit a black cat in a dark room , blindfolded... and the cat may not even be there...It is a bad idea to blindly make a board , slap on some parts and then cry that it doesn't work. it's even a worse idea to raise the middle finger if someone tells you your approach is wrong and that there are easier hobbies.... like basketweaving ( that was a joke by the way )and that's all i'm going to say about that.

author: c4757p
author_rank: Super Contributor
timestamp: May 01, 2013, 12:41:59 am
content: Quote from: free_electron on May 01, 2013, 12:37:30 amOh, it's definitely there. Andnotthere, simultaneously in a superposition of - oh wait, you saidroom...

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 02:22:05 am
content: Quote from: free_electron on May 01, 2013, 12:37:30 amI didn't have anything to do with making the spectrum analyzer. It's powered by a ATmega64. It uses a digital potentiometer to get the various bands. The spikes are an admitted fault from the person who designed/made it. It's not noise from the audio source. It happens with nothing connected to the input. He won't explain the problem in detail. It's a fault on this specific revision.It's all going in a gutted 5.25" CD drive, but I might just bend up a piece of thin aluminum plate instead.

author: David_AVD
author_rank: Super Contributor
timestamp: May 02, 2013, 02:33:44 am
content: OMG this thread is entertaining and disturbing at the same time.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 02:49:36 am
content: Quote from: ramicio on May 02, 2013, 02:22:05 amIf I had to make a diagnosis, I'd say the design's probably retarded. Not "retarded" as in "that paint color's retarded, I don't like it", but more as in "it's going to hurt itself, put it out of its misery". Why are you averse to modifying it?QuoteSubdiagnosis: He doesn't have a damned clue what the problem is. Not even a hunch.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:15:37 am
content: Quote from: c4757p on May 02, 2013, 02:49:36 amAverse to modifying what? I have to come ask for help in designing something to clean up noise in a power line, you think I could actually do something like design and code a spectrum analyzer? I told ya it was retarded. I don't even know why someone would think of using a digital potentiometer to be varied very fast to get bands instead of using some open source FFT library. Just about all LED spectrum analyzer kits have done something like switching between frequency filters to feed a bar graph driver whose output goes through a column selection section. This thing has 20 columns and 20 rows. That would be 40 bar graph drivers. It would probably work flawlessly and not have a visible refresh rate pulse to it, but the circuit would be massive thanks to the 3915 being only through-hole DIP. It would also need 401 signals to interface between boards instead of 40. It was a choice between a fast response and low accuracy or high accuracy and something that would probably not be so responsive on an ATmega64.He likely does have an idea, he is just very closed and secretive about the design and source of the thing. It was not there in previous revisions. It's a product for the guy, not a project. He also likely didn't tell me because it would just go over my head anyway.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:18:17 am
content: Not to be rude - but you don't even have an oscilloscope. How do you even know the noise is from the power supply? Hell, for all we know the spikes are being generated in software by an erroneous algorithm. You are likely to be barking up the wrong tree.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:21:48 am
content: Because it's not noise. It's a single spike that occurs every few seconds. The guy said to use a linear supply and bypass the one on the board. If you think this is all wrong, go to youritronics.com and try to get it out of him what the deal is.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:26:26 am
content: To me thatreallysays it's not on the power supply. What power supply has sub-Hz spikes?? Spikes over 100kHz, sure, but below 1 Hz? Nope. I'm guessing it's a stupid software error - some buffer is overflowing periodically, the watchdog timer is expiring, he forgot to bang his head on the desk at just the right angle before coding - whatever, but Ihighlydoubt a "spike every few seconds" is coming from the power supply.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:27:55 am
content: The go over there and tell him that he's full of it.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:33:05 am
content: Quote from: ramicio on May 02, 2013, 03:21:48 amQuote from: ramicio on May 02, 2013, 03:27:55 amIf you cannot get a straight answer from him yourself, you should not bother to do this. Why are you even doing it, anyway?I'm trying to help you figure this out because I wanted to help you. I really couldn't be bothered to go tell this guy how much he sucks, and I doubt he'd give me any more information than he'd give you. I've got much more interesting problems to work on. You've reached a dead end unless you can get this guy to move his ass and fix his design, and I'm not going to keep dancing around his inabilities for you.Ipromisethis isn't power supply related. No power supply hiccups like that. But there's no more I can do for you at this point.

author: oPossum
author_rank: Super Contributor
timestamp: May 02, 2013, 03:44:09 am
content: Info from the mfg:http://www.youritronics.com/forum/post2626.html#p2626Quotehttp://www.youritronics.com/forum/post2633.html#p2633Quotehttp://www.youritronics.com/forum/post207.html#p207Quote

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:48:34 am
content: There it is. I forgot he said that, it was so far back. And it actually does spike during audio being played. One nice thing about this was that he told me about this spiking crap after I paid.If it was from the onboard SMPS switching modes, why would it happen with a completely different supply with that whole thing removed? He's basically stated that he has no interest in improving this thing other than this spiking issue, despite almost 3 years ago saying there is going to be a version 3 with FFT. There is someone else who basically makes the same thing, but with FFT, but it's one giant board. That won't work for me. And in the videos the thing seems pretty slow. Since it just sits there in the video, I have no idea if it's the camera that is slow or the device.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:52:45 am
content: Why does anyone do anything? Because they want to. I want an LED audio spectrum analyzer in a 5.25" drive bay that has fast, fluid response.

author: Niklas
author_rank: Frequent Contributor
timestamp: May 02, 2013, 05:49:25 am
content: I checked the picture of the PCB available at:http://www.youritronics.com/forum/download/file.php?id=92&mode=viewThere can be stability issues with SMPS circuit, up in the right corner, related to poor layout with long traces. A workaround can be to remove the output inductor L1 and to patch in an LM7805 with proper bypass and buffer capacitors. Ceramic (X7R) or film 100nF in parallell with 100uF electrolytic on both the input and the output of the LM7805. In the attached picture the patch wires are shown but not the capacitors on the voltage regulator.Perhaps the TO220 package of the LM7805 can be thermally connected to the large copper fill on the LED display board for heat sinking?

author: KJDS
author_rank: Super Contributor
timestamp: May 02, 2013, 07:56:23 am
content: Run it off a battery. If that cleans it up then it's a power supply issue

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 12:55:55 pm
content: I don't own any batteries.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 01:16:37 pm
content: If you won't even buy a battery then we're back to "string, chewing gum and wishful thinking", and if you can't afford a battery you're not going to make this work no matter how much you'd like to. That's like saying "here's $5, how can I build a spaceship?"

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 01:18:12 pm
content: Quote from: ramicio on May 02, 2013, 03:52:45 amDesign it yourself. You'll learn a hell of a lot more that way.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 01:18:26 pm
content: Stop making assumptions. I don't own any batteries because I find them useless. The only portable electronics I use is my phone. Everything else I like to be corded.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 01:20:56 pm
content: I wasn't making assumptions, I was listing a possibility so I wouldn't have to come back and address it if it turned out correct.Quote from: ramicio on May 02, 2013, 01:18:26 pmYou've now been proven wrong, as we've found a use for them, so go buy some.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 01:22:46 pm
content: Quote from: c4757p on May 02, 2013, 01:18:12 pmI can't learn it, therefore I don't want to learn it. If I have to ask how to design a simple filter, do you really think I could learn to code some microcontroller? I bought into the PIC thing thinking there would be tutorials that were easy, but it was beyond me. I had to pay someone to write me a program to do a simply on/off with a button.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 01:25:25 pm
content: Quote from: ramicio on May 02, 2013, 01:22:46 pmQuoteDo you know what a "beginner" is?? Of course there are things you don't know! Stop being lazy and keep trying! Fuck, do you think I was born knowing about electronics and programming?You need to pick up a book. That's the only way you're going to solve your problems. And if you had to pay someone to write you a program to "do on/off with a button" you're not even trying.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 01:28:22 pm
content: These things arehard. I have years of experience with both (more experience with programming, actually) and that's how I can see solutions to problems like this.Go work your ass offand get the experience! No, you're not going to have this done today. Probably not this year. Such is humanity, I'm afraid; you can't just lay your head on a textbook or your computer screen and expect the knowledge to embed itself into your brain through osmosis. There are no 'easy' tutorials because programming isn't easy.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 01:35:29 pm
content: It's not about being a beginner. I know the limitations of my intelligence, and this is not something I will ever be able to do. I am not unrealistic in this regard. I don't waste my time with things I am naturally not good at. It's not about knowing something, it's about being able to understand it. Again, making more assumptions like "you're not even trying." Some people are born with artistic abilities, and some people are born with technical abilities. A person who can't draw or paint will never be able to learn to do so. Their brain is just not wired for it. I can tell you that I am not intelligent enough to understand how to do this. I absolutely cannot pick up a book and learn things. I failed every area in school that required me to read something to learn it. I only learned anything by hearing it being broken down by another human. I am not being lazy.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 01:41:08 pm
content: Quote from: ramicio on May 02, 2013, 01:35:29 pmYou do not.QuoteSome people would call this "effort".QuoteProve it. You brain does not have wires. It is conditioned by your prior experiences. You can recondition it, it's justreally hard. Doing really hard things when they need to be done is the sign of not being lazy.QuoteThen the sources you had did not explain it in a way you understood. Find others.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 01:53:09 pm
content: How do I not know the limitations of my intelligence? You're getting downright insulting.I don't waste my time with stuff I am not good at because I know the end result will be far from my standards, so it's not worth doing. It's all or nothing with me. I would rather channel my effort into things I am good at. Some people might call this sound logic. The world is too full of people lately who think they are good at something but actually such at it because trendy yuppies have taken control of society and criticism is taboo as long as there is sound effort. Natural talent is now ignored and people are taught that they can be great at something by merely putting in the effort.I don't need to prove anything to you. If you can't understand this through observation in every day life, then you just aren't looking. Some people are good at math, some people suck at it. Numbers are a certain way of thinking and people who don't understand it cannot have it taught to them no matter how good the teacher is or how they try to alter the interpretation of it to fit the student. Some people are artists, some are not. It's the way the brain is wired to be able to coordinate hand movements to what the eye sees. You cannot be taught how to be an artist. Some people can remember trivia and other other useless knowledge, and some people can't remember the name of the person they've just met.I looked at many sources. It had nothing to do with how it was explained, it's that my brain does not operate in the manner required to be a programmer.

author: KJDS
author_rank: Super Contributor
timestamp: May 02, 2013, 01:59:10 pm
content: Quote from: c4757p on May 02, 2013, 01:20:56 pmSo I've come up with the perfect way of identifying if it's the power supply that's the issue and the OP won't spend the price of a beer on some batteries, but it's our fault for not designing a circuit for him to do something but we don't know what it needs to do.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 02:02:44 pm
content: It's already been quoted here that the designer knew it was the power supply on the thing. I didn't ask anyone to design me a circuit. If I would have you would see offers being made to pay people to do so. I wouldn't have to buy just batteries, I would have to also buy something to put them into. It's not about money, it's about practicality. I don't own any method transportation, so I would have to order such things and pay for shipping.

author: free_electron
author_rank: Super Contributor
timestamp: May 02, 2013, 02:45:27 pm
content: The designer of that board has given a solution. Get a 7805 regulator , wire it up as shown and it will work. A 7805 cost 0.5$.The designer also gave an explanation. The switching power supply he designed is faulty. The core saturates and this collapses the output voltage for a short moment. Most likely the atmel keeps running but the analog portion goes crazy and this shows up as a glitch. Anyway.Get a 7805 , wire it up as shown and it will work.No kind of filtering before the regulator can help as the problem is in the regulator backend.And dont come with excuses as i dont have money i do t have transport i dont have yadadayadayada. You got this spectrum analyser and you have a computer . So you have money to buy those and you managed to get them at your place which implies a form of transport.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:01:15 pm
content: Quote from: ramicio on May 02, 2013, 01:53:09 pmEvery word of that was utter bullshit. Your brain can be trained to operate that way, just as anybody's brain can learn to be an artist. Youcanteach somebody to be an artist. You cannot teach somebody whodoes not care, which is, I suspect, the cause of this common misconception. You refuse to learn, so you will not learn. And yes, I am getting insulting, because I'm getting impatient.You have a problem and a solution, implement it and you're done. But stop expecting everybody to solve your problems. You're not incapable of learning this stuff. If you don'twantto bother with it I can understand, but don't try to do it, then refuse to do the actual "work" part of it.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:01:52 pm
content: I'm most likely just done with this project. The fact that this thing does not have fine bands puts me off. It basically just goes up and down with beats. It's basically a VU meter repeated to 20 columns. Look how the thing acts with a steady 1 kHz tone played to it. Not only does it register on all bands, but it bounces from a steady tone.http://youtu.be/FqhcEvGjE84I would take it upon myself to make something better myself, but as I said before I am just not capable of it and it would cost me too much money. It would only make sense for me to make something to produce and to profit from, but it's such a niche and expensive thing that it's not worth pursuing. I have a feeling this guy just did this for some school project and decided to make some extras and sell them. If it was a serious product he wouldn't make statements indicating that it's not worth his time and money to improve it.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:02:37 pm
content: Quote from: free_electron on May 02, 2013, 02:45:27 pmOnly slightly off topic - any idea why this would happen every few seconds? I don't think I've ever seen a DC-DC converter that saturates its core just occasionally on that sort of time scale.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:06:25 pm
content: Quote from: ramicio on May 02, 2013, 03:01:52 pmThat's bad.QuoteI'm not going to keep telling you you can do it, because you don't seem to believe me, but if you change your mind, I think your idea of doing it with FFT was solid. A dsPIC microcontroller has all the facilities you need to do this at audio frequency. It will not be an easy project for a beginner, but it is definitely doable.

author: oPossum
author_rank: Super Contributor
timestamp: May 02, 2013, 03:10:30 pm
content: Quote from: c4757p on May 02, 2013, 03:02:37 pmPossibly beat frequency between regulator glitch and ADC sampling. The ADC would have to sample at just the right time to see the power supply glitch that is likely quite regular.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:11:32 pm
content: Quote from: ramicio on May 02, 2013, 02:02:44 pmHow does food get to your kitchen? I'm going to assume you don't slaughter your own cows? Use that method to acquire batteries.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:12:15 pm
content: Quote from: oPossum on May 02, 2013, 03:10:30 pmAh - good point. I forgot there's no oscilloscope here to show the true glitch frequency.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:26:41 pm
content: Quote from: c4757p on May 02, 2013, 03:01:15 pmYou're just spouting a bunch of trendy new age nonsense. Every person is born with strengths and weaknesses. You cannot teach a person to be an artist, but a person can be educated on forms of art. It's not even really education, it's just a person seeking what previous artists they find inspires them. No amount of teaching is going to make a person who can only draw stick figures into some kind of Michelangelo. Your kind of thinking is why art is turning into crap. We have people who suck at what they do because their mommies and daddies never told them that they have no talent. They are just taught that all that matters in life is being happy. It's blind optimism and it's a mental illness. Well, spending time of stuff I do not understand and therefore can't perfect sure doesn't make me happy, so I spend time doing things I do understand, and therefore enjoy. I am logical. I don't purposely go around frustrating myself. Only masochists constantly invite pain and frustration into their lives. I have been on this earth long enough to know what I am good at and what I suck at.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:32:28 pm
content: Just because I can walk to a store a few blocks away for food does not mean there is a place that sells electronics stuff withing walking distance. Having to pay for shipping for a battery holder and a 7805 is not a good use of money.Yeah, FFT is a good idea, but it's not doable for someone like me who lacks the intelligence to get it done. I suppose an actual retarded person could learn to be a rocket scientist?

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:35:09 pm
content: I will admit that I could probably do it, but not from scratch. I would have to start with someone's else code.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:36:38 pm
content: Quote from: ramicio on May 02, 2013, 03:35:09 pmOf course. Nobody here invented the entirety of electronics and programming in a void.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 03:59:01 pm
content: Quote from: ramicio on May 02, 2013, 03:32:28 pmYes, because that's exactly the same thing as saying someone who's already demonstrated a casual understanding can improve.QuoteAre you trying to be a twit on purpose to back up your "I'm too stupid" argument? Who needs a battery holder? Tape some wires to a couple 1.5V cells. I'm sure they have them. 4.5V will be enough, and I'm sure you can find some broken piece of crap somebody's giving away to rip a regulator out of if you insist on a full 5.0V.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 03:59:58 pm
content: Could you recommend where to start regarding the dsPICs? Are they powerful enough to get this done with a very fluid refresh like a visualization you would see on a music player program on a PC? If I could get away with it speed-wise, I would probably go with more bands and resolution. Maybe 32x32, if that's sane. If not, 32x16 would be good.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 04:12:07 pm
content: Quote from: ramicio on May 02, 2013, 03:59:58 pmYes. The dsPIC33F, which I recently used, goes up to 40 MIPS. That means you can fit in 1250 instructions for every single sample at a 32 kHz sample rate. Even some very inefficient code should have no problem running a real-time FFT at that rate.QuoteThedatasheet. (Well, the specific one for whichever device you end up using.) There's a lot there, you'll want to sit down with a good, large cup of coffee and have a couple reads through it. That will give you an idea of its capabilities.Then get one. If you can get an affordable development board for it, do that, otherwise you'll have to roll your own. It's not really complicated, a dsPIC is a long way from an FPGA or something. You'll need to run it at 3.3V, not 5V - trap for young players. You can use anything that can program PICs to program it (PICkit is reasonably affordable), and the software is free from Microchip. Start small - get it to flash an LED, and then get it to read analog values from the ADC.QuoteYou can do 32x32 with that chip.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 04:15:01 pm
content: Here's a dev board for $30.It needs the chip itself and an external programmer. Their official programmer costs $100 but it can be made to work with a PICkit instead, I'm sure. (Disclaimer: I've never used it. I started with my own board for that chip.)

author: baljemmett
author_rank: Unknown
timestamp: May 02, 2013, 04:22:06 pm
content: Quote from: c4757p on May 02, 2013, 04:12:07 pmThe Microstick II (or "Microstick for dsPIC") might be worth a look -- about $30 from memory -- it's a combined USB programmer and breakout board for the 28-pin DIP dsPIC / PIC24 / PIC32 devices, and includes a selection of PICs to get you started (including a dsPIC).

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 04:32:11 pm
content: Awesome! Comes with the chip, built-in programmer - very nice. Yes, I recommend that too.

author: free_electron
author_rank: Super Contributor
timestamp: May 02, 2013, 04:32:24 pm
content: I dont get it.. A 7805 is obviously too much trouble to fix the thing we already spent money on. Everything else is too complex but we are going to throw oodles of money on a devkit , programmer and invest time and money making a new one. You will need to buy led's and other electronics, make a pcb and more. This will also cost money....All that to have some blinkenlights in a computercase ? That thing doesn't even serve a real purpose.It's not a piece of testequipment.. .all it does is blink leds on a music beat...Upsidedown world ...

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 04:38:46 pm
content: Quote from: free_electron on May 02, 2013, 04:32:24 pmNot just to have blinkenlights, to learn how to make blinkenlights. They're just as electronic as any other project a beginner could embark on.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 04:39:34 pm
content: I do already have a PicKit 2. The dsPIC33 looks to be what I need if I were to do 32x32.It's not about too much trouble to fix it. The power supply is only part of the problem. The main problem is that it's just a flashy piece of crap with no real accuracy. The problem is that itdoesjust blink to the beat of music, so it's not that much of a spectrum analyzer. Free_electron, you just need to unsubscribe from this thread if your input is just going to be that this doesn't matter because it's just blinking lights in a computer case and that it serves no real purpose. How did you learn about electronics? I'd imagine by making "pointless" little trinkets and working your way up.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 04:40:23 pm
content: Quote from: c4757p on May 02, 2013, 04:38:46 pmYou get it. While it may not serve some purpose in a lab environment, it's something that DOES serve a purpose by teaching me and making my computer look cool.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 04:48:52 pm
content: Quote from: ramicio on May 02, 2013, 04:39:34 pmHe is somebody you should listen to. Maybe points of opinion like "it's not worth the effort" can differ, but he knows what he's talking about with electronics.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 05:20:48 pm
content: 362 pages. That will take urns of coffee.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 05:29:06 pm
content: I see our misunderstanding - I call that a "cup". Takes me about 30 min to finish.

author: ramicio
author_rank: Regular Contributor
timestamp: May 02, 2013, 06:01:24 pm
content: I'm sitting here going off on tangents in my head and I realized I could do a 32x32 display with only 10 IO pins, so I don't need one of these huge QFP chips.I spoke too soon. I don't think any binary decoder exists that keeps the lesser values low. They just output a single line.

author: free_electron
author_rank: Super Contributor
timestamp: May 02, 2013, 08:58:54 pm
content: Quote from: c4757p on May 02, 2013, 04:38:46 pmYou misinterpreted what i wrote.When i suggest a 0.5$ solution in the form of a 7805 that is considered too much trouble...Yet embarking on a fairly complex bit of fft code and a led matrix scanni, building a new led matrix , learning how to write code, get a dspic , make aboard for the display .. That is not too much trouble...Especially after the ranting about 'not being avle to learn programming'.That's the bit that doesn't make sense to me....I'm all for learning and tinkering with electronics. But the amount of 'lip' we got in this topic when trying to suggest even simple thing like a lowpass filter or the 7805 ... It just makes me wonder.Every other post we were met with : i don't have ( pick your choice ) money, tools, transport, knowledge, skill, brains ...Yet, there was money and transport to get this nonfunctional 'hood ornament' in the first place.And now we are embarking on something that will require tools,knowledge and brains as well..What's goingto be next ? I live in the jungle and there is no electricity ?There will be soldering involved... You will have to construct that 32x32 array of led's. either design you own board or do it on perfboard. You cant do that using two planks of wood and three nails...Now, on a more constructive note.If you wantto keep the pincount low: do the column addressing using a shiftregister. Just clock a single 1 around. I would make shift registers out of 74574's. the pins are neatly in order.Tie the clk lines together. Connect the q0 to D1, Q1to d2 and so on. The last q7 goes to d0 of the next one.Now all you need is two cpu pins. Set one pin low and give 32 pulses on the clk line. This erase whatever is in the registers. You only do this at startup. Now you make the pin high , give one clock pulse and make the pin low. This makes q0 of the first 74574 high. Ever new clock pulse moves this bit one position. After 32 clocks you have scanned the entire array.The way the pins are ordered in a 74574 makes it very simple to construct the shifter.You can connect the outputs of the 74574 to uln2803 and drive all the currentyou want.So you can scan the array woth two pins in horizontal direction.For the vertical you could do the same approach. There i would double buffer. Meaning i follow the shifter by a latch. I transfer the shifter contents to the latch using the same clock edge that progresses the scan shifter.With 5 or 6 pins you can control the array.Hook that into an interrupt handler driven from an internal counter and you don't need to think about it.The fft generates 32 numbers ( one for each column) the int handler simply reads them one by one and advances the scan counter. Every interrupt you update one column. This will give you plenty of computing throughput.

author: Bored@Work
author_rank: Super Contributor
timestamp: May 02, 2013, 09:14:28 pm
content: Did you consider that you are being trolled?

author: cwalex
author_rank: Frequent Contributor
timestamp: May 03, 2013, 03:00:51 am
content: Quote from: Bored@Work on May 02, 2013, 09:14:28 pmI reckon that is probably the case. Just in case it isn't, to the OP, if you find that programming and electronics is "too hard", I don't think calling yourself "not intelligent enough" is necessarily true. If you think that a few months of tinkering, reading and experimenting it too much work then you probably just picked something that you aren't really interested in.I know I have hit that wall with a few subjects that sounded like a great hobby or subject to pursue only to find that once I reached the details I wasn't interested enough to spend the required amount of time to learn the fundamentals of the subject or just realised that I didn't find it as interesting as I initially thought I did.You can't take on a project like this as a goal if you aren't prepared to spend hundreds and hundreds of hours reading, tinkering and experimenting on the way to the goal and you have to enjoy the process of getting to the goal as much or more than achieving the goal otherwise it would be like torture getting there or someone else will have to do all the heavy lifting for you and you will just be "painting by numbers".If you are prepared to work hard and show it, you will find a lot of help here on the forum. If not then you will not feel very welcome I suspect.

author: c4757p
author_rank: Super Contributor
timestamp: May 03, 2013, 04:01:07 am
content: Quote from: Bored@Work on May 02, 2013, 09:14:28 pmNo, and despite how much of an ass I'll look like if I'm wrong, I still don't think that's the case. The quick switch of attitude from "I'm an idiot who can't learn anything" to "I'm ready to learn something" is odd, but perhaps more the mark of confusion than trolling.

author: ramicio
author_rank: Regular Contributor
timestamp: May 03, 2013, 01:01:11 pm
content: I don't troll (if trolling is just going around arguing for the sole purpose of trying to get a reaction). I'm just a deeply-troubled individual. Thanks for the patience.