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PDP-1 posted:Also remember that the pins on the microcontroller have a maximum current rating. For an Arduino Uno the internet says it's 40mA (0.040A) max, 20mA continuous, and that all the pins on the chip together shouldn't draw more than 200mA. This only applies if you're driving the LEDs directly off the microcontroller. So each of the 8 outputs on the 74HC574 that is being used to control 8 annode columns can handle 25mA, but the whole chip can only handle 50mA. That leaves 6.25mA for each column of 8 LEDs. Which is fine, but they said they ended up going with resistors of 100ohm at 5v. It looks like they used blue LEDs like I am which have a forward voltage of 3v. Unless I'm missing something here that would mean they would be pulling 160mA.
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Aug 6, 2023 18:55
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Bad Munki posted:So this is working out great! Thanks to this thread, my project has officially entered a "live and operational" phase! Full accounting here: https://forums.somethingawful.com/showthread.php?threadid=2734807&pagenumber=127#post533717530
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Aug 6, 2023 19:12
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Oh, you want more drive current? Throw out the 74HC574 and use these instead: 74FCT374. You will need to swap some pins going from 574 -> 374, but they are functionally compatible.
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Aug 6, 2023 19:28
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Stolen… Op Posted it in the osha thread
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Aug 7, 2023 03:54
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namlosh posted:Stolen… While I wouldn't recommend doing this at home, in some circumstances it's not totally crazy. Tesla coils (I think that's what they are sitting on) operate at such high frequencies that a phenomena called the 'skin effect' takes over from how current flows in normal DC wires. Basically Maxwell's equations kick into high frequency mode and the current flows on the outside edges of a conductor, be that copper wire or a human. I work at a university physics lab and we have a Tesla coil that was built by two of my now retired colleagues who were notorious high voltage geeks. We use it now for school group demos, we start out showing the sparks it throws off, then light up a fluorescent light bulb at ~1 meter distance, then talk about how Tesla wanted to transmit power wirelessly but how it couldn't work efficiently because we set up one antenna close to the coil and one in the back of the room and feed them both into an oscilloscope that shows how fast the fields drop off. For the final bit of the demo we try to explain that out Tesla coil is operating at super high frequencies, unlike the power sockets in your wall at home, so don't try this yourself... and then stick our fingers into the sparks causing our fingertips to light up like some kind of nerdy sith lord. It feels like someone is snapping a mildly taut rubberband onto your finger tips, but the skin effect keeps the current flowing on the outside of our bodies away from our nerves and internal organs. I never would have agreed to try it if one of the old volthead engineers hadn't done it multiple times in front of me. It's a good demo, but your fingers stink afterward since the sparks burn whichever part of your epidermis they happen to land on. Anyway, enjoy these dudes in chain mail armor playing around with an even bigger set of Tesla coils: https://www.youtube.com/watch?v=3FpjcOWwiI4
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Aug 7, 2023 04:37
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It has nothing to do with the skin effect, but with the fact that your nerves and muscles do not respond to frequencies of 100khz-3MHz, the average tesla coil working frequency. Even if there's skin effect in the very imperfect conductor that is the body, you should definitely feel the current impacting all the more superficial nerve endings and nociceptors in your skin. Either way, you can get nasty burns from it. I had a little oopsie with a 15w radio transmitter's loop antenna which started to have tesla coil aspirations. Tuning cap flashed over to my finger while tuning it. Didn't feel it until things started heating up, i had a little crater in my finger tip for months.
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Aug 7, 2023 09:23
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I’m trying to avoid a wall wart in my greenhouse project, as I’m currently looking at scope creeping a Pi Zero into the mix. Don’t need a ton of power, don’t want to mess around with mains voltage, or worry about isolation transformers or whatnot. So based on googling, it looks like my best bet would be to get a little board mount power supply, and go from there. Looks like the zero wants 5V@1.5A max, so I’m thinking a unit like this would work fine? https://www.digikey.com/en/products/detail/mornsun-america-llc/LD10-23B05R2/13531052 5V, 2A max, fully enclosed, through-hole, and just a couple cubic inches, which would easily fit within the greater enclosure. Am I on the right track here?
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Aug 8, 2023 06:02
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Bad Munki posted:I’m trying to avoid a wall wart in my greenhouse project, as I’m currently looking at scope creeping a Pi Zero into the mix. Don’t need a ton of power, don’t want to mess around with mains voltage, or worry about isolation transformers or whatnot. So based on googling, it looks like my best bet would be to get a little board mount power supply, and go from there. Is there any other low voltage on your project? A buck converter works fine for a Pi Zero eddiewalker fucked around with this message at 07:34 on Aug 8, 2023 |
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Aug 8, 2023 07:32
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Technically yes, but it’s the power for some lights, which this will be dimming and/or turning off by way of the dimmer control line on the light’s power supply itself. Otherwise, nothing but 120. So, effectively no, no consistently available low voltage.
Bad Munki fucked around with this message at 16:07 on Aug 8, 2023 |
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Aug 8, 2023 16:04
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bit of a long shot but does anyone here have any experience with the altera usb blaster (the FPGA programmer) or more specifically the cheap clones from ebay/aliexpress?
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Aug 9, 2023 15:09
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I would blow Dane Cook posted:bit of a long shot but does anyone here have any experience with the altera usb blaster (the FPGA programmer) or more specifically the cheap clones from ebay/aliexpress? I use an Altera USB blaster occasionally at work, but have never used the ebay clones. What's your question?
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Aug 9, 2023 18:07
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I was able to install the driver and get it recognized by windows easily enough. But I have not been able to get it to show up in the quartus prime programmer software. Tried different computers. Even tried linux. I am now trying to get another one to try.
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Aug 10, 2023 04:02
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I would blow Dane Cook posted:I was able to install the driver and get it recognized by windows easily enough. But I have not been able to get it to show up in the quartus prime programmer software. Tried different computers. Even tried linux. I am now trying to get another one to try. I'm not at work right now, so I can't check the configuration. Also, I'm not sure what Quartus we use, but I don't think it is Prime. With whatever version of Quartus we use, it doesn't have the Altera as an option - just select USB. I think that even though we are connecting through JTAG, we select Active Serial (instead of JTAG) and it works. I don't know or understand the communications protocol at all, but I hope that maybe gives you a couple things to try.
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Aug 10, 2023 04:21
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I'm going to try to get my hands on another one and give that a try.
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Aug 10, 2023 05:26
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Is there a better alternative to Eagle these days? I'm not trying to do anything wild, I just need to make a schematic & PCB for like a dozen components. It's been long enough since I used Eagle that it's a good time to consider learning alternatives for this project.
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Aug 11, 2023 03:49
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I don't know if it's better, but I used Kicad recently and the process was pretty smooth from schematic, to PCB and ordering.
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Aug 11, 2023 03:51
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I haven't used Eagle but yeah, another vote for KiCad. It's the only one I've used for my hobby work over the years and KiCad 7 is pretty drat good.
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Aug 11, 2023 03:56
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I prefer KiCad to Eagle at this point, with the caveat that I jumped off the Eagle train at around 7.0 or wherever they went to subscription-only mode. KiCad <4.0 was kind of bad, then v5 got acceptable and v6 got actually good. KiCad v7 has a lot of quality-of-life improvements that make doing normal stuff a lot easier. Autodesk announced that they are gonna kill off Eagle as a stand-alone product within the next year. It's getting rolled into Fusion 360. e: Apparently June 7, 2026 is the end of the line for Autodesk Eagle support. PDP-1 fucked around with this message at 04:51 on Aug 11, 2023 |
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Aug 11, 2023 04:48
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I'll also pile on to Kicad. I switched years ago as I didn't like that Eagle wanted you to pay even for something like four layers, which is fairly basic these days (especially given how fancy the chips you can buy on Digikey/etc. are). It felt close enough to Eagle, which I had already decided was terrible anyway, but since it was also free Kicad had many more features. Only issues I ever had with Kicad were the fact it appears to support the "SpaceMouse Compact" and I happened to have one plugged in, and it apparently has a lot of bugs in that area as it'll just crash at random even if you're not using the SpaceMouse, and every major release I have to update all my files as every component for whatever reason gets broken, but at least that's easy enough to fix.
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Aug 11, 2023 05:05
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My only problem with kicad is that it's missing a lot of the quality of life features I'm used to in Altium. But other than that, it's excellent.
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Aug 11, 2023 05:17
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Altium has a free version and a one-time “Pro” version that’s only missing like advanced DFM and high speed features. If you want the Altium QoL
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Aug 11, 2023 05:55
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As a long time Altium user - avoid it if you can. It is a bloated, buggy mess. It's very powerful but it's not very intuitive and has decades of features interacting in... Interesting ways. KiCAD is a much cleaner experience, and I'm really hoping it gets a few more QoL features added and eventually kills Altium in industry.
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Aug 11, 2023 06:14
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So far so good with KiCad, seems pretty straight forward and SnapEDA exports parts for it, which helps greatly. Navigating the interface is way more comfy than Eagle, seems to come a lot quicker and I'm dodging fewer extra systems that I don't want to care about than with Fusion's nonsense. Is there a way I can align parts on a PCB based on a feature? That is, I'm putting a 2x20 pin header on my board so I could slap a Raspberry Pi Zero on there as a daughterboard, I'd like to line the pins up so I can place some through holes for standoffs at the far end. I just added the Pi to my schematic and laid it over top, I got it lined up what appears to be perfectly by just adjusting the grid and shifting it until it looked right, and now I can place some holes beneath the Pi's holes, but it'd be cool if I could just say "center this pin on that pin"
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Aug 11, 2023 06:36
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For stuff like that I just got the diagram for the part I wanted to mate with, worked out the important numbers, and made really sure they were in the right place on KiCad. Occasionally I even made it a part (like a really big connector with pins all over the place) to make sure I didn't mess it up at the PCB end, if it was complicated, though annoyingly the Kicad footprints can't do cutouts or something like that (though I think it's planned to be fixed). There might be a better way. I've also done the opposite, and import Kicad's 3D model into Fusion 360, which worked okay. Wish I could figure out FreeCAD though, it is not to Fusion 360 what Kicad is to Eagle/etc.
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Aug 11, 2023 06:44
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Realizing that the 2x20 pin header would stand the Pi far enough off to comfortably fit 100% of my other components directly underneath it was cool, though, if I go with SMD, which I might as well if I'm having a board made. Gonna make this thing tidy as heck.
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Aug 11, 2023 06:45
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I've got some 24V DC multicolor LED tape on a dimmable controller that works via common-anode PWM. It works fine, except whenever I'm using a camera the PWM causes that flickering banding effect when the lights are dimmed beyond a certain point. Can I just slap a capacitor across it to smooth that out or is that gonna break the controller?
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Aug 11, 2023 20:44
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Shame Boy posted:I've got some 24V DC multicolor LED tape on a dimmable controller that works via common-anode PWM. It works fine, except whenever I'm using a camera the PWM causes that flickering banding effect when the lights are dimmed beyond a certain point. Can I just slap a capacitor across it to smooth that out or is that gonna break the controller? IIRC it's the strobe rate of the lights interacting with the frame rate of the camera. From a camera perspective you can usually change the frame rate on the camera so that they aren't lining up. If you have a cheap camera you can instead try adding more light to trick the system into using a faster framerate, but if you're filming LEDs of course you probably have a certain scene in mind. Capacitor I don't think will do anything, it's not flickering due to power delivery (I think).
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Aug 11, 2023 20:47
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VelociBacon posted:IIRC it's the strobe rate of the lights interacting with the frame rate of the camera. From a camera perspective you can usually change the frame rate on the camera so that they aren't lining up. If you have a cheap camera you can instead try adding more light to trick the system into using a faster framerate, but if you're filming LEDs of course you probably have a certain scene in mind. The flickering during the dimming specifically is due to it spending more time off than on in the PWM cycle, you can reduce that a bunch by either dimming less (so it spends more time on than off, and so the chance of the camera catching it during the off time is lower) or presumably by smoothing out the waveform so it never actually turns all the way off. However thinking about it some more I'm not sure a capacitor would actually help for common-anode setups... And yeah you could eliminate it entirely by messing with camera framerates... for a single LED strip, but I have more than one, on independent controllers, that are almost certainly running at different frequencies and completely out of phase.
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Aug 11, 2023 20:52
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If you're putting the capacitor in parallel with the LEDs themselves at the output of the PWM controller (not at the supply of the controller like I think VelociBacon is assuming) it'll ruin the dimming effect because while the PWM switch is open the current will just come from the capacitor instead. The best way to dim LEDs without flicker is regulating the current.
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Aug 11, 2023 21:04
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Stack Machine posted:If you're putting the capacitor in parallel with the LEDs themselves at the output of the PWM controller (not at the supply of the controller like I think VelociBacon is assuming) it'll ruin the dimming effect because while the PWM switch is open the current will just come from the capacitor instead. The best way to dim LEDs without flicker is regulating the current. Oh right the controller will just supply more current when it's on because it's not constant-current to begin with won't it, hm ok. Well does anyone know any Zigbee RGB WW CW LED tape drivers that use current regulators instead of PWM lol 
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Aug 11, 2023 21:09
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 Mount one of these to my board for pretty low-current 120VAC, or just solder directly? It’ll be going from that (through a fuse on L) to a fully enclosed transformer that outputs 5V@1A max. No I don’t plan on having to disconnect the wires, like, ever.
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Aug 11, 2023 22:05
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Depending on how the circuits of the LEDs are set up, you could just make a rudimentary buck converter between the PWM signal and the LEDs.
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Aug 11, 2023 22:06
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Shame Boy posted:Oh right the controller will just supply more current when it's on because it's not constant-current to begin with won't it, hm ok. No, they won't exist. More expensive PWM drivers will have a higher PWM rate and work better with cameras. Your cheapo guy probably uses 500 or 1000Hz, which is fine for human eyes, but bad for camera equipment. Search on Ali for a decoder that can do 5kHz or 10kHz, both should be readily available. Alternatively, use 100% duty cycle on yours to eliminate the flicker, then whack a beefy resistor in line to drop the intensity. Adding a cap, as mentioned, won't do what you want to do
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Aug 11, 2023 22:52
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Bad Munki posted:
Never solder wires directly to a pcb. These days, consumer devices like TVs use connectors internally. Only the cheapest consumer junk and toys solder wires directly.
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Aug 12, 2023 02:50
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I made a 'flicker eliminator' for a photographer friend. It's just a bridge rectifier and filter cap inside an outlet strip. Most LEDs bulbs are flicker-free running on 170V DC. e: this is not a solution for PWM/shutter aliasing
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Aug 12, 2023 02:55
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ryanrs posted:Never solder wires directly to a pcb. These days, consumer devices like TVs use connectors internally. Only the cheapest consumer junk and toys solder wires directly. I will admit that a fair portion of my design sense probably comes from tearing apart the cheapest consumer junk and toys. Plus, Wago levers are just great always.
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Aug 12, 2023 03:04
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namlosh posted:Stolen… I worked with large tesla coils back in university. The reason the guy in the middle isn't shrieking in pain is because he's holding a wire in his hand which is connected to the topload. The little wire is a far better conductor than his body (even at high frequencies) so all the current passes through it instead of him. If the other end of that wire were severed for just a second... he probably wouldn't be dead but he'd likely suffer some nerve system damage and subcutaneous burns wherever the arcs decided to form on him.
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Aug 12, 2023 18:29
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Splode posted:As a long time Altium user - avoid it if you can. It is a bloated, buggy mess. It's very powerful but it's not very intuitive and has decades of features interacting in... Interesting ways. Now eagle is basically a dead end. If there's a version of Eagle which meets your needs, and you can use it without cloud/subscription garbage, then by all means keep using it. I still fire up 6.60 for small jobs. If not, KiCad seems like the hands down winner. Every time I try and teach myself KiCad I get hung up on how they handle libraries. Symbols and footprints in different libraries.... what.... gently caress it, next weekend. On the other hand, KiCad adding ODBC database support is potentially game changing. However I've found very few examples of people using it so far, and it looks like actually setting up requires a great deal of effort, and expertise in SQL/database stuff, which I don't have. But if the community continues to invest in developing database support (and BOM management), I could see a lot of small companies switching over from Altium or whatever.
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Aug 12, 2023 18:49
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I’m pretty happy with KiCad so far. I’ve just been grabbing symbols and footprints from SnapEDA, some of my parts only have either a symbol or a footprint there, so either I’ll have to learn the kicad editor or, more likely, I’ll just pick variations on those parts that are fully specced on Snap 🤣
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Aug 12, 2023 18:59
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ANIME AKBAR posted:I would say this about every large eCAD software I've ever used. What makes me laugh is when "big name" CAD software also comes with some random schematic/PCB tool. Fusion 360 has one, Solidworks bundles a cut down version of one they sell separately I think, all the reviews say they're terrible. Why would you want to use the electronics software that randomly came with your overly expensive 3D CAD app?
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Aug 12, 2023 21:29
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