|
Cory Parsnipson posted:Huh, that's weird. Why did they lay out a whole board if they didn't need half of the components? OP said it was a demo unit, so it looks like they didn't bother putting in a speaker, a battery, some clock setting ability, and maybe some other stuff, based on the silkscreens
|
#
?
Jun 5, 2021 04:06
|
|
|
|
| # ? May 29, 2024 10:28 |
|
|
petit choux posted:They wanted to save on floor demos. It's a big retail chain, they did a short run of a few hundred probably. Also it's designed to only play a few seconds of like 4 pieces of music and then shut down. ante posted:OP said it was a demo unit, so it looks like they didn't bother putting in a speaker, a battery, some clock setting ability, and maybe some other stuff, based on the silkscreens Ahh gotcha. I missed that chunk of text in the middle.
|
|
#
?
Jun 5, 2021 04:27
|
|
|
I’m bored at work and currently vivisecting an ancient Nokia Tracfone. I have extracted the electret mic capsule.  I’m used to seeing these with discreet solder pads. I’m assuming the center is positive and the outer perimeter is the ground. Marsupial Ape fucked around with this message at 05:16 on Jun 5, 2021 |
|
#
?
Jun 5, 2021 05:13
|
|
|
Marsupial Ape posted:Edit: Ok, I found a legitimate AC-to-AC variable transformer. I'm not going to buy it, but I am now emotionally satisfied. Now, I'll shut up about it. Shame Boy posted:a variac (kinda bulky and expensive for what you're trying to do but it'd work), If you like Variac, how about Scariac? Marsupial Ape posted:I’m bored at work and currently vivisecting an ancient Nokia Tracfone. I have extracted the electret mic capsule. Assume all you like. Without a datasheet, it's literally as good as guessing. Two pads? 50/50 shot. There's literally no reason for one to be one or the other; the OEM of the device could pick whatever polarity they want because they commissioned ten thousand of the things, so they write the specs.
|
|
#
?
Jun 5, 2021 10:59
|
|
|
babyeatingpsychopath posted:Assume all you like. Without a datasheet, it's literally as good as guessing. Two pads? 50/50 shot. There's literally no reason for one to be one or the other; the OEM of the device could pick whatever polarity they want because they commissioned ten thousand of the things, so they write the specs. "These giant heat sink tabs are always ground, right?" Later on... "Why is nothing working but everything getting really hot?" -- me, as a young engineer
|
|
#
?
Jun 5, 2021 13:58
|
|
|
babyeatingpsychopath posted:If you like Variac, how about Scariac? Well, the outer ring is touching the aluminum body of the capsule, making it the best candidate for ground. edit: while I'm at it about electrets, I'm going to be fabricating some stereo (dual capsule) lavaliers for my brother, today. These will be powered by the plug-in power of his DSLR and other recorders. Normally, I just just joint the positive and negative directly to the capsules and that's fine. Is there anyway I can introduce a passive equalizer or bias into the connection with a resistor and cap? Marsupial Ape fucked around with this message at 15:58 on Jun 5, 2021 |
|
#
?
Jun 5, 2021 14:28
|
|
|
While I wait for the final parts for big microphone build to come in, I’ve decide to put together a Frank’s Box. For those of that aren’t TurboNerds that grew up listening to Coast to Coast AM, a Frank’s Box is a device for communicating with ghosts and aliens and poo poo. Basically, it’s a radio that has had it’s auto-scan function to never stop, hitting on active frequencies for only a moment. You ask whatever extra planar entity you intend to contact a question, turn on the Box, and whatever random loving words the scan lands on is your answer. It’s very stupid and I want to say I made one. Here is an online retailer’s page for their DIY Ghost Box kit. They are dumb enough to show the individual circuit boards. It’s a very simple design using inexpensive Chinese parts from eBay. I have already identified them all and there’s maybe 20 bucks of parts, there, and they’re selling it for 100 GBP. Yeesh. Anyway, if anybody has an design insights or suggestions for more appropriate parts (I’m pretty sure that pulse circuit is not optimal), I’d appreciate it.
|
|
#
?
Jun 7, 2021 06:21
|
|
|
Marsupial Ape posted:While I wait for the final parts for big microphone build to come in, I’ve decide to put together a Frank’s Box. For those of that aren’t TurboNerds that grew up listening to Coast to Coast AM, a Frank’s Box is a device for communicating with ghosts and aliens and poo poo. Basically, it’s a radio that has had it’s auto-scan function to never stop, hitting on active frequencies for only a moment. You ask whatever extra planar entity you intend to contact a question, turn on the Box, and whatever random loving words the scan lands on is your answer. It’s very stupid and I want to say I made one. LOL no. Just checking in to say I'm getting a resistor substitution box, and probably getting one for capacitors too, with an eye to eventually circuit bending some of these cheap keyboards I've got lying around.
|
|
#
?
Jun 7, 2021 06:34
|
|
|
petit choux posted:LOL no. We’ll see how much you laugh when the Ascended Masters give me the winning lottery numbers. Or I start selling them to local ghost hunting groups. But, yes, I also ordered a collection of common passive components, too. I need to do more bread boarding so I can actually understand circuit diagrams.
|
|
#
?
Jun 7, 2021 06:41
|
|
|
Improvements: LFO with a fart
|
|
#
?
Jun 7, 2021 07:03
|
|
|
Marsupial Ape posted:We’ll see how much you laugh when the Ascended Masters give me the winning lottery numbers. Or I start selling them to local ghost hunting groups. At the rate you're going you're going to be an ascended master yourself pretty soon, or at least compared to me. That's okay, I'll have one more bright mind to ask my dumb questions of as I take poo poo apart.
|
|
#
?
Jun 7, 2021 16:04
|
|
|
petit choux posted:At the rate you're going you're going to be an ascended master yourself pretty soon, or at least compared to me. That's okay, I'll have one more bright mind to ask my dumb questions of as I take poo poo apart. Thank you for the compliment, but that is not the case. I have a bad habit of diving in to deep to a new subject and then working my way back to the beginning.
|
|
#
?
Jun 7, 2021 22:49
|
|
|
Not sure if this is the right place to ask this question, but I'm having some electrical interference issues at my new house playing guitar. I'll try to explain this as succinctly as I can. I get loud humming/distorted noises through my guitars pickups, when I play at my PC in the corner of the living room. My PC, router/modem/TV are all right there. This was never an issue at the old house. The light switch on that wall goes to my ceiling fan, which also has a light dimmer, which might be part of the culprit here. Turning the light on/off doesn't affect the noise though. However, turning all my electronics off does make about 90% of the noise go away. If I pick my guitar up and move to the other side of the living room, the noise also goes away. It also seems to be all the electronics causing the noise equally that are plugged into that side of the living room rather than just one specific piece of equipment. Will running an extension cord and plugging my electronics up to an outlet on the other side(I can plug an amp in this outlet and play without the noise although if I sit down at my computer the noise comes back which is why I know it's my guitar picking it up and not coming through my amp or anything) probably help? I know you can line the guitars control cavity in copper foil, but I'm not sure if I'll have to remove all the electronics to do that, which would be a giant pain in the rear end since I have several guitars. If I wrapped a piece of cardboard in foil and kind of attached it to my desk to block the power strips/modems/outlets from my guitar would that make any difference? This got recommended in the Guitar thread, would it likely help if I used it instead of a regular power strip for my electronics? I know cutting my electronics off helps, and I know my electronics by themselves didn't really cause any issues before moving here, so plugging them into this might clean up some of whatever the issue is. https://www.sweetwater.com/store/detail/SS6Block--furman-ss-6b-6-outlet-power-strip Drunk Driver Dad fucked around with this message at 23:03 on Jun 7, 2021 |
|
#
?
Jun 7, 2021 22:54
|
|
|
I'm no expert in guitar electronics, but since you seem to be picking up electrical noise in a way that you didn't experience before you could have a broken ground connection somewhere. If you just moved to a new house and the problem suddenly appeared the ground break may be in the outlet itself which would be a good thing to know about. If you use an extension cord to run your amp off of another plug (ideally one far away and not on the same circuit that you're using now) does the noise go away when you play it near all of your electronic stuff? That would be a pretty good clue that the issue is in the outlet. I wouldn't advise a non-expert to go sticking multimeters into the wall plug without training, but if you Google "outlet ground tester" you can find some commercial outlet testers for pretty cheap. If that does end up being the problem you'd want to get an electrician to come fix it for you because it means that nothing else plugged into that outlet is grounded either.
|
|
#
?
Jun 7, 2021 23:20
|
|
|
Is your guitar cable properly shielded? A faulty or unshielded mic/instrument cable will act as an antenna around sufficiently strong EM fields.
|
|
#
?
Jun 8, 2021 00:46
|
|
|
PDP-1 posted:
Drunk Driver Dad fucked around with this message at 02:08 on Jun 8, 2021 |
|
#
?
Jun 8, 2021 02:04
|
|
|
Marsupial Ape posted:Is your guitar cable properly shielded? A faulty or unshielded mic/instrument cable will act as an antenna around sufficiently strong EM fields. I'm not sure, but I have 2 guitar cables and it doesn't make a difference which one I use. It seems to just be my guitar picking it up from what I can tell.
|
|
#
?
Jun 8, 2021 02:05
|
|
|
Does your guitar have a humbucking pickup or a dual-pickup switch position? If it does and it doesn't significantly cut down on the noise you're getting I'd start looking for broken wires under the pick guard.
|
|
#
?
Jun 8, 2021 02:45
|
|
|
Drunk Driver Dad posted:I'm not sure, but I have 2 guitar cables and it doesn't make a difference which one I use. It seems to just be my guitar picking it up from what I can tell. I've done a little Googling and forum browsing, so this is not from my own experience. What appears to be happening is that your computer and possibly monitor are putting out an EMF field being picked up my the wires and magnets in your guitar's pick ups (like a radio). This field is usually only has a radius of 4-5 feet and can easily blocked by your body. That's why when you turn in your chair the buzzing goes away. Computer cases are poorly shield, so you can drape your computer in copper foil or shield your guitar. Hope this is the fix.
|
|
#
?
Jun 8, 2021 02:52
|
|
|
Stack Machine posted:Does your guitar have a humbucking pickup or a dual-pickup switch position? If it does and it doesn't significantly cut down on the noise you're getting I'd start looking for broken wires under the pick guard. So I have a few guitars, they all do it. The one with active pickups does it less, but that's to be expected compared to the one with passive pickups. So guitars aren't faulty or anything. Also it's not just my monitors or computer case themselves, I've had these guitars and computer for a while and it was fine until I moved, it's something with this house 100%. It might be because there's a dimmer on that circuit or something making the electrical signal more noisy than usual. I'm going to get one of those power strips like I linked earlier and hopefully that will cut it down. Also I'll try an extension cable and seeing if plugging my electronics into that other outlet will help. Drunk Driver Dad fucked around with this message at 03:00 on Jun 8, 2021 |
|
#
?
Jun 8, 2021 02:57
|
|
|
Drunk Driver Dad posted:So I have a few guitars, they all do it. The one with active pickups does it less, but that's to be expected compared to the one with passive pickups. So guitars aren't faulty or anything. Hell, get wacky. Try using the extension cord to plug the computer and monitor into an outlet across the room.
|
|
#
?
Jun 8, 2021 03:15
|
|
|
Does the buzz get louder or quieter if you, while holding the guitar, touch the computer case? If it changes at all this might be a grounding issue. Adding a power strip with extra filtering will probably help whether or not it is, but getting the guitar amp and computer both connected back to the same high-quality ground at one point is a good start.
|
|
#
?
Jun 8, 2021 04:36
|
|
|
Marsupial Ape posted:What is generally considered the standard magnification and diopter for soldering work? I need a magnifying lamp bad. A page late but eBay has these clip on lenses for phones that rule pretty hard for soldering. I like them because I can set the phone on a tripod and then set the board at the right height and it’s really fast and easy to make adjustments of my phone tripod
|
|
#
?
Jun 8, 2021 05:31
|
|
|
Drunk Driver Dad posted:Not sure if this is the right place to ask this question, but I'm having some electrical interference issues at my new house playing guitar. I'll try to explain this as succinctly as I can. I get loud humming/distorted noises through my guitars pickups, when I play at my PC in the corner of the living room. My PC, router/modem/TV are all right there. This was never an issue at the old house. The light switch on that wall goes to my ceiling fan, which also has a light dimmer, which might be part of the culprit here. Turning the light on/off doesn't affect the noise though. However, turning all my electronics off does make about 90% of the noise go away. If I pick my guitar up and move to the other side of the living room, the noise also goes away. It also seems to be all the electronics causing the noise equally that are plugged into that side of the living room rather than just one specific piece of equipment. Yeah, get one of those little outlet testers if you haven't already, see if your power actually has a ground fault. Offhand that sounds like your culprit. One other thing you might try is if you have a UPS around, try powering your amp momentarily on the UPS with it unplugged, and if you don't get that noise it should tell you something about your wall power. I also purchased a couple of those Furmans you linked, I think they help keep the noise out of your signal, always a good thing for making music. Also, there are these little isolation transformers you can get if you really must, they don't cost a whole lot. I used to go to a work site occasionally that had a police radio dispatch next door, the RFI would wreck my speech recognition. I either used one of those or just ran on battery all day and charged up during lunch. Of course my power draw wasn't that great and I don't know what those things can handle but I'm seeing some with much higher capacity than the little portable one I had. petit choux fucked around with this message at 13:06 on Jun 8, 2021 |
|
#
?
Jun 8, 2021 12:04
|
|
|
I tried touching my pc, along with just touching other things. Didn't affect the noise at all. I'm thinking it's not a grounding issue then. I still suspect the dimmer switch in my ceiling fan, since it's on the same circuit my electronics are plugged into. Still haven't gotten an extension cord yet to test out other outlets.
|
|
#
?
Jun 8, 2021 22:14
|
|
|
Yeah I'm leaning toward noise coming from wiring now. The fact that it doesn't change when you touch things screams "magnetic" (as opposed to electrical, the noise can get in through an electric field like a capacitor or magnetically like a transformer), and magnetic coupling is all about the shape of the current path (romex good, knob-and-tube bad) and the harmonic content of the current going to your appliances (dimmers, LED lamps and computers: bad, resistive loads good, but also typically more current so possibly also bad). Filtration will knock some of the harmonics down on that current waveform going into the computer which should help, but you can't add that power strip to the dimmer circuit, so maybe play with the lights off? Taking load off of the wiring near your desk and running an extension cord to somewhere else might help too, but it's not really good fire-wise to just leave extension cords in long-term service.
|
|
#
?
Jun 8, 2021 22:39
|
|
|
If running it off an extension cord from a different circuit (or sticking it on a UPS to completely isolate it from mains) makes it better, it's a conducted noise problem, which is easier to fix than radiated. You may be able to brute force it with clip on ferrites cleaning up the incoming power.
|
|
#
?
Jun 8, 2021 23:41
|
|
|
I fabricated a BootLegMic for my brother, this morning. He didn't ask for one, but I made it and now he has it. I wasn't able to test its ability to reduce distortion, but it recorded fine when I plugged it into my Zoom H1n (so the circuit works!) Just another step on my path to perfecting a DIY lavalier mic. Still have to find a better electret mic capsule.  Finished product is protected with heat shrink tubing. Marsupial Ape fucked around with this message at 00:12 on Jun 9, 2021 |
|
#
?
Jun 9, 2021 00:02
|
|
|
Did some more testing. So turning the lights off doesn't "fix" the problem, but turning the lights on/off does make the noise make some weird sounds as the lights come on and off. That power strip thing I linked that reduces noise also has a long cable, I could get it AND plug it into another outlet. Would that be a fire hazard like running an extension cord though? Drunk Driver Dad fucked around with this message at 02:16 on Jun 9, 2021 |
|
#
?
Jun 9, 2021 02:04
|
|
|
Really as long as the cord isn't being stepped on or rolled over with a chair or something and is kept visible/easy to see if it's fraying either is mostly OK, but the power strip has one less connector that could remain half-pulled-out for years without being noticed so it's more-OK.
|
|
#
?
Jun 9, 2021 03:27
|
|
|
Not saying go out and buy this, but this is what I used to use at one or two worksites that had issues with noise from the electrical system messing up my speech recognition:  And BTW, is there other stuff on the same fuse in other rooms that you haven't examined? You are probably onto something with your light, you could always try putting an incandescent bulb in, that may make a noticeable difference.
|
|
#
?
Jun 9, 2021 04:41
|
|
|
Trick ghost hunters into ‘investigating’ your ‘haunting’. They’ll be waving enough EMF detectors around that you should be able to pin down your source. poo poo…I should make an EMF meter.
|
|
#
?
Jun 9, 2021 04:46
|
|
|
Marsupial Ape posted:poo poo…I should make an EMF meter. That's pretty much what a Software Defined Radio is
|
|
#
?
Jun 9, 2021 14:31
|
|
|
Marsupial Ape posted:Trick ghost hunters into ‘investigating’ your ‘haunting’. They’ll be waving enough EMF detectors around that you should be able to pin down your source. Actually an EMF meter's a great idea for a project. From what I understand there's nothing too complicated in them and you wind up with a thing that's real entertaining to play with. Could probably even find some example schematics and try designing one yourself if you feel up to it and want to learn what all the parts are. Forseti posted:That's pretty much what a Software Defined Radio is Oh yeah, also get an RTL-SDR and a cheap antenna to play around with some time if you haven't already. They both can be had for dirt cheap and it's just darn novel being able to sweep across a huge swath of the radio frequency spectrum and see all the weird poo poo you can find. Like you can use it to look at the "shape" of FM radio broadcasts, which really helped me conceptualize the whole "frequency modulation" thing. It becomes a lot clearer when you're watching a spectrum chart of an FM channel roll past you on the screen while listening to it at the same time, suddenly you see how the signal changes based on what you're hearing and suddenly it becomes a hell of a lot more obvious how "changing frequency" can encode the sound.
|
|
#
?
Jun 9, 2021 14:50
|
|
|
Working on a project where I want to read 20 sensor outputs "simultaneously". The outputs are all slowly varying DC, and I figure a sampling rate of ~2 Hz per sensor should suffice. My thinking was to use a 24-pin analog mux controlled by an MCU to iterate through each channel (at about 40 Hz). In looking at spec sheets, I'm surprised how high the on resistances are -- like 100ohms or more. I don't really know where I'm going with this, other than to say I thought this was weird.
|
|
#
?
Jun 9, 2021 19:05
|
|
|
Cyril Sneer posted:Working on a project where I want to read 20 sensor outputs "simultaneously". The outputs are all slowly varying DC, and I figure a sampling rate of ~2 Hz per sensor should suffice. My thinking was to use a 24-pin analog mux controlled by an MCU to iterate through each channel (at about 40 Hz). In looking at spec sheets, I'm surprised how high the on resistances are -- like 100ohms or more. I don't really know where I'm going with this, other than to say I thought this was weird. Standard old-school CMOS switches are like that, you can get higher performance ones at a cost. For high voltage use (i.e. +-15 V) the ADG45x is a good choice, there are also low voltage variants with similar performance. I actually built (professionally) a 32 channel system capable of 14/16 bit operation with 600 Hz per channel a few years ago where I used 4x ADGxxx muxes (5 V variants, can't remember which). Note that the on resistance is typically non-linear with signal level, which causes non-linear distortion, especially if you have any loading on the output. My suggestion: if you have more than one ADC, you can split the design into e.g. 3x8 bit muxes with 3 ADCs to speed up the sample rate or give longer acquisition times. Take special care with allowing sufficient settling times when changing channel - IIRC you should wait for at least 10x the slowest RC time constant of the circuit to get a ~16 bit accurate result. You can do a lot less settling for e.g. 12 bit resolution. The fix for all your settling time and on-resistance issues is often to use a fairly high speed buffer opamp right after the mux. This means your mux output loading is low, resulting in low distortion, and fast settling. Slew rate may be more important than actual gain-bandwidth here. This opamp will also provide a consistent low impedance ADC drive, meaning you can run the ADC faster without sacrificing accuracy. Also note: there will be some leakage between channels, if your source impedance is low this is typically not a factor. If the source impedance is high then you would need to buffer it before the mux (which is a huge pain for a 20 channel system). And obviously ideally you should include a low pass filter per input with a cutoff below nyquist (adding an input cap also reduces the effects of charge injection when changing channels). Consider oversampling and filtering digitally.
|
|
#
?
Jun 9, 2021 20:10
|
|
|
Cyril Sneer posted:Working on a project where I want to read 20 sensor outputs "simultaneously". The outputs are all slowly varying DC, and I figure a sampling rate of ~2 Hz per sensor should suffice. My thinking was to use a 24-pin analog mux controlled by an MCU to iterate through each channel (at about 40 Hz). In looking at spec sheets, I'm surprised how high the on resistances are -- like 100ohms or more. I don't really know where I'm going with this, other than to say I thought this was weird. Dominoes fucked around with this message at 02:22 on Jun 10, 2021 |
|
#
?
Jun 9, 2021 20:18
|
|
|
Shame Boy posted:Actually an EMF meter's a great idea for a project. From what I understand there's nothing too complicated in them and you wind up with a thing that's real entertaining to play with. Could probably even find some example schematics and try designing one yourself if you feel up to it and want to learn what all the parts are. I’ve been looking and there are a ton. I may go full art project and put on in a enclosure with an LED strip indicator and clicker that rise with intensity. Paranormal investigators have a who cargo cult mentality when it comes to scientific measuring devices (if I have enough high end EMF recorders and audio recorders, surely the ghosts will come to me!), so there are a bunch of DIY resources.
|
|
#
?
Jun 9, 2021 20:41
|
|
|
longview posted:Standard old-school CMOS switches are like that, you can get higher performance ones at a cost. For high voltage use (i.e. +-15 V) the ADG45x is a good choice, there are also low voltage variants with similar performance. Hmm, lots of things I hadn't thought about - thanks!
|
|
#
?
Jun 10, 2021 02:55
|
|
|
|
| # ? May 29, 2024 10:28 |
|
|
Fyi. New and so far, great book and website in electronics design, geared towards product development: http://designingelectronics.com/
|
|
#
?
Jun 10, 2021 15:58
|
|