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PRADA SLUT posted:I suppose I don't need it, but I just output the entire thing and zip it to send off. it's just an extra step I need to remember. If you're using Altium, learning how to create an output job file (and having a go-to template) is a life-changing skill. My guess is the fab house got confused that you included a drawing for a keepout and made an incorrect assumption about why. quote:This was my thought, so it goes: PMIC > 100pF > 100n > IC ? Not sure where you're getting 100pF. That's tiny, and the datasheet you linked shows a much more reasonable 10uF. You want something big on the output of your power supply so it can absorb any surge demand that would otherwise dip your supply voltage. Otherwise, yes, the idea is correct. Sometimes larger ICs will also want a bank of larger bypass caps to smooth out larger swings, or multiple caps at different VCC inputs, but they'll usually say so in their own datasheets. In general, just take a salt shaker full of 0.1uF caps and go to town. The thing to remember is that a capacitor to ground is a rudimentary low-pass filter. The higher the capacitance, the slower it charges and discharges (i.e. lower corner frequency), but the more capacity it has to smooth out a higher magnitude perturbation. Smaller caps are better at filtering high frequency noise, but can't handle as large of a perturbation. So it's not uncommon to put some big caps in parallel with some small caps (smallest always closest to inputs) to handle a variety of different kinds of noise.
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Dec 11, 2021 01:59
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100pF was a typo, I’m following the data sheet for the two caps (and will add another by the input to the IC). For output I’m using Altium, I think I just marked “export visible” and let it rip. One other thing. If I have an antenna in the center of my board (or, not at the edge), should I extend the keep out to the edge or does it matter if have a “pocket” in the middle? PRADA SLUT fucked around with this message at 07:41 on Dec 11, 2021 |
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Dec 11, 2021 07:37
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An antenna in the middle is going to be suboptimal almost no matter what you do Also now my curiosity is piqued
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Dec 11, 2021 07:50
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https://twitter.com/Papapishu/status/1469390989211099145?s=20 now this, this i can get into
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Dec 11, 2021 12:33
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I've been thinking a lot about powering things with DC in the house. Especially if my next house (or god forbid, I get to build something) lets me put up as much solar as I want. Running DC wiring of any size around the house seems pointless, but I was wondering how far I could go with PoE, basically. If I run multiple CAT5e/6 to every room (like, literally ~4 runs to every room at least). Then using a main LiFePo battery bank off the solar you could power a PoE switch basically directly, or through a high efficiency buck/boost to the standard 57 volts. I could make some simple non-isolated DC/DC converter modules for PoE to power anything that runs off a 5-12v wall wart or USB. There are some pretty high efficiency converters with integrated switches that are pretty simple to use these days, and auto switch to a pulse skipping mode and the like when at low load. Also you could even do something like run RS422 over the two data pairs and do PoE over the others, so small micros could talk MQTT or serial back to a central raspberry pi for home automation integration, even though a regular PoE switch was doing the power part. I'm not sure total efficiency would necessarily be amazing, though I suspect most wall wart adapters other than maybe high end phone chargers are probably absolutely awful already. And it could limit the size of 120v inverter needed, and allow me to transition loads off to solar gradually even if the system wasn't large enough to make direct tie-in to the 120v system useful immediately.
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Dec 11, 2021 21:11
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I think maybe you were coming to the same conclusion as me by the end of your post, but, outside of it being cool, what do you gain from that strategy? You have Solar->PoE->wall wart voltage conversion stages. This is probably marginally more efficient than solar->AC->DC. The wires will also have marginally more DC resistance than AC impedance. At each outlet, you need a special PoE->5v(or 12V, or 3.3V, or whatever) converter, whereas you have a million cellphone chargers in that one drawer that everyone has.
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Dec 11, 2021 21:29
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ante posted:I think maybe you were coming to the same conclusion as me by the end of your post, but, outside of it being cool, what do you gain from that strategy? Probably a few partial things? 1) If I need a PoE setup anyway, and have a lot of cat5/6 run to all the rooms anyway, there's a bit of 'why not take advantage'. 2) It would let me start to run stuff on a smaller solar system without hard-wiring in a halfway solution or paying for an all-the-way solution right away. 3) I was intrigued by the pros/cons of wifi requiring an outlet for power vs PoE providing data & power wherever I might have a rj45. Obviously there's situations where either might make more sense. 4) Losing my goddamn poo poo every time I can barely fit 2 wall warts and 2 plugs on a power strip with 8 outlets. There may be nothing on earth I hate more than loving wall wart adapters that extend sideways instead of 'upwards' and even the skinny ones ALWAYS go the wrong direction so they block like 3 outlets minimum. I guess circling around from #4 there, I was thinking about, is there a better way to power all this DC poo poo than stupid loving 120v & wall warts everywhere. Either using USB for everything and USB hub power blocks (and then needing wifi for data) or PoE seemed like the only existing options I could think of. And as common as USB is I think making devices that draw more than 5W and use the weird standards isn't always super easy either. Like if I have some existing thing that draws 12v 1a, it's probably easier to make a PoE adapter for it than somehow powering it off USB. Rescue Toaster fucked around with this message at 22:27 on Dec 11, 2021 |
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Dec 11, 2021 22:24
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FWIW, my DC strategy around the apartment has been to drop a 12v and 24v psu of at least 10 amps on each floor and run 2 conductor cables terminated in DC barrel plugs as necessary. I have multiple ESP8266 units scattered around that act as dimmer controllers for LED strips and for temp/humidity sensors. They have buck convertors on them to drop to 5v as necessary for the microcontroller, and the LED strips run off the 12 or 24v directly. POE is only used on hardware that can actually make an ethernet connection back to the switch too, such as IP cameras and raspberry pi touch screens in kiosk mode showing home automation controller pages in chromium.
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Dec 12, 2021 00:28
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Where the gently caress is my wireless power transmission, I've been promised this for decades
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Dec 12, 2021 01:21
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ante posted:Where the gently caress is my wireless power transmission, I've been promised this for decades Nikola Tesla was about to unleash wireless power on the world, but Thomas Edison and his cabal of lizard men replaced Tesla with a clockwork elf and then destroyed the knowledge for wireless power.
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Dec 12, 2021 01:27
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everything on the planet runs on wireless power transmission
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Dec 12, 2021 01:29
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Sagebrush posted:everything on the planet runs on wireless power transmission Reductio ad absurdum implies that I can claim using a stick to turn off my lights is "remote control," too.
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Dec 12, 2021 19:03
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What the hell do I do with a fricking fog machine
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Dec 12, 2021 19:40
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ickna posted:FWIW, my DC strategy around the apartment has been to drop a 12v and 24v psu of at least 10 amps on each floor and run 2 conductor cables terminated in DC barrel plugs as necessary. I have multiple ESP8266 units scattered around that act as dimmer controllers for LED strips and for temp/humidity sensors. They have buck convertors on them to drop to 5v as necessary for the microcontroller, and the LED strips run off the 12 or 24v directly. My thinking was ethernet in the walls is cleaner and you don't have to run heavier gauge wiring for 12v. Plus if you do end up wanting ethernet at the location... bonus. In theory some things like lighting and such could be run at the nominal PoE voltage and no DC/DC converter if you could come up with a ~48v LED bulb/string. Basically my thought process was just focused on: If I have a large ~48V nominal battery bank for a solar system, is there an clean/interesting way to power specifically DC or other low-power devices around the house without going to 120v and back, and without making a mess of the house and wiring? If I already have PoE for cameras, wifi access points, etc... is there any sense doing something in parallel or just use PoE for everything? If I had lots of cat6 running everywhere, could that be taken advantage of for IoT devices or sensors that were too simple to warrant ethernet? Since you can swap out the 2 data pairs and do RS422 instead of ethernet but keep the PoE. Probably the next step is just try to buy a couple off the shelf PoE power adapters for 12/5/3.3v and see how awful they are, and maybe price out a small PCB for my own if I wanted to build some for kicks.
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Dec 12, 2021 23:02
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I don't really have an opinion on your plan for PoE everything but Rescue Toaster posted:If I had lots of cat6 running everywhere, could that be taken advantage of for IoT devices or sensors that were too simple to warrant ethernet? Since you can swap out the 2 data pairs and do RS422 instead of ethernet but keep the PoE. it's generally a bad idea to use one kind of cable/connector with a well-defined purpose in a non-standard way, because sooner or later you or anyone else who ever needs to interact with the wires are gonna forget that this is the Weird Line and try to plug a laptop into it or whatever and maybe blow something up.
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Dec 13, 2021 00:15
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Rescue Toaster posted:I've been thinking a lot about powering things with DC in the house. Especially if my next house (or god forbid, I get to build something) lets me put up as much solar as I want. Running DC wiring of any size around the house seems pointless, but I was wondering how far I could go with PoE, basically. If I run multiple CAT5e/6 to every room (like, literally ~4 runs to every room at least). Then using a main LiFePo battery bank off the solar you could power a PoE switch basically directly, or through a high efficiency buck/boost to the standard 57 volts. I suspect it pencils out like this AC/DC transformer losses are something like 15% on average, under 10% if you buy high end transformers. transformers cost N and are easy to replace, literal plug and play wall warts Putting DC in the walls is very expensive, you still have to put in high efficiency DC/DC transformers which are difficult to replace My guess is you just replace your high load devices with DC versions where available (washer/dryer, fridge, stove, AC, water heater) and then upsize your solar array by 20% to account for AC/DC transformer losses elsewhere The only time I'd go through the hassle of running 48v DC alongside/to replace 120v AC would be on like a van or boat or something which is like 8 outlets in an 8x30' space across a single plane (no two story+basement)
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Dec 13, 2021 00:37
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Shame Boy posted:I don't really have an opinion on your plan for PoE everything but Only tangentially related but I have nothing but burning hatred for people who use USB connectors in a non-standard way, especially if their use requires USB A to USB A cables.
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Dec 13, 2021 08:11
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babyeatingpsychopath posted:Reductio ad absurdum implies that I can claim using a stick to turn off my lights is "remote control," too. Yes.
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Dec 13, 2021 08:15
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BattleMaster posted:Only tangentially related but I have nothing but burning hatred for people who use USB connectors in a non-standard way, especially if their use requires USB A to USB A cables. Ah yes, DC widowmakers
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Dec 13, 2021 08:47
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How do you feel about people using cat5 for stepper motor <-> driver connections? Asking for a friend
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Dec 13, 2021 08:57
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My work somehow uses a proprietary directional cat 5 cable that is visually indistinguishable from normal cat 5 and the sockets are just normal cat 5 sockets and it drives me INSANE. Installers constantly mixing it up with normal cat 5 or not realising it's directional or trying to crimp it themselves like it was normal cat 5.
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Dec 13, 2021 10:40
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Crossover cables? I'm intrigued, how the gently caress do you have a proprietary cat 5 crimping pattern? My laptop in 2001 had auto sensing for crossover cables, but I doubt any modern hardware supports that since the last time i saw a crossover cable was about 2006 when I threw mine away
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Dec 13, 2021 10:51
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3. Pin-out In some cases it might be needed to make the cable at the location. Find below the pin-outs. Make sure to very carefully test the cable after crimping it. Self-made cables are very often the causes of very hard to diagnose problems. 3.1 Type A Function | Victron VE.Can side | Battery side GND | Pin 3 | Pin 6 CAN-L | Pin 8 | Pin 5 CAN-H | Pin 7 | Pin 4 3.2 Type B Function | Victron VE.Can side | Battery side GND | Pin 3 | Pin 2 CAN-L | Pin 8 | Pin 5 CAN-H | Pin 7 | Pin 4
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Dec 13, 2021 11:07
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petit choux posted:What the hell do I do with a fricking fog machine Same thing as any electrical device, watch some Big Clive about it  He loves smoke/fog machines and has tons of videos about them https://www.youtube.com/watch?v=bySTH6H_REs
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Dec 13, 2021 15:46
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any machine is a fog machine with enough volts
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Dec 13, 2021 15:47
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gonadic io posted:any machine is a fog machine with enough volts This kinda goes nicely with your AV
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Dec 13, 2021 19:03
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I was going through a box of cables someone threw out, and as if to mock me, there was a USB A to A cable in it. I wonder what cursed piece of equipment needed that? Or if they had tried to connect two computers together with it. The world wonders
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Dec 13, 2021 21:28
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The first USB device I designed needed one, back in 2011 or so I did not have a good grasp of the different roles of USB ports
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Dec 13, 2021 21:47
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I think you might be able to do it with USB3, but A to A on USB 1 or 2 would connect the power supplies of each computer to each other and you'll have a bad time.
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Dec 13, 2021 21:58
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Strange question, but we have an old fiber optic desktop xmas tree that uses a small weird 12VAC motor to spin a color wheel in front of a lightbulb. The motor burned out and I got a replacement, but it is 5rpm vs the original which was about 2rpm. Is there a way to limit that speed without lowering the voltage to the bulb? Would something as simple as wiring them in parallel and just a resistor on the motor leg work? This is assuming it can even run with voltage under 12vac. Simplist solution would of course be a 6vac wall wort, but the bulb is non dimmable. Motor is listed as 1-2W. Bulb is 10W.
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Dec 13, 2021 22:14
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I had to make an A-to-A cable to get two dev boards to talk to each other. One had a device mode but still only had a normal A socket. Of course both had hardwired 5v supply so I had to cut the 5v line in the cable otherwise.... boom. I think more than one board was lost to that.
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Dec 14, 2021 00:58
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I work on a thing now with an A to A cable. It goes from an internal pcba to an A to A bulkhead passthrough on the case. For whatever reason, AA bulkheads are more common than AB
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Dec 14, 2021 01:10
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Bulkhead USB connectors are frequently, bafflingly female A on both sides, necessitating an A to A cable to make it a functional connection. Edit: beaten. Left tab open too long.
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Dec 14, 2021 03:26
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BattleMaster posted:I was going through a box of cables someone threw out, and as if to mock me, there was a USB A to A cable in it. I wonder what cursed piece of equipment needed that? Or if they had tried to connect two computers together with it. The world wonders  Ok this is good timing cause I almost bought one of these yesterday... I have a raspberry pi with a USB hub attached to it and an Arduino acting as a USB HID device hanging off the hub. I was going to get this cable to hook up my laptop to the hub and see if I could communicate with the Arduino from my laptop without disconnecting the whole RPi/Hub/Arduino setup. Is... this a bad idea?
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Dec 14, 2021 04:43
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If the device is, for some god-forsaken reason, designed to work with a USB A to A then I guess it will work. If you're assuming it will work but don't know enough specifics about the hardware to properly judge whether or not it will work, then don't do it. If you don't know what you're doing, you risk creating a low-resistance path between two slightly-different 5V supplies that will cause a whole bunch of current to flow through the cable and, if it doesn't have good current limiting, you risk blowing a fuse or destroying hardware - or turning the cable itself into an ad hoc fuse. The only safe way to connect USB devices is to use standard cables (that is, a USB A (host) to B (device) cable) and devices that follow the standard properly.
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Dec 14, 2021 04:55
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BattleMaster posted:don't do it. If you don't know what you're doing, you risk creating a low-resistance path between two slightly-different 5V supplies that will cause a whole bunch of current to flow through the cable and, if it doesn't have good current limiting, you risk blowing a fuse or destroying hardware - or turning the cable itself into an ad hoc fuse. Hadlock posted:Ah yes, DC widowmakers
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Dec 14, 2021 05:08
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I design a lot of USB electronics, and sometimes some poo poo will just randomly smoke because we forgot that our debugger (on a different ground) was hooked up when we plugged USB power in or whatever
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Dec 14, 2021 05:09
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When I'm debugging my devices I always quadruple-check that my debugger is set to measure, not source, the voltage. Allegedly it has current limiting but I don't want to tempt that. edit: I built something a couple years back that needed USB passthrough bulkheads and the parts I bought were sane enough to use A on one side and full-size B on the other, like I'd expect. Anyone making ones with A on both sides don't know what they're doing but I guess I shouldn't be surprised that some people think that's a good way to do things BattleMaster fucked around with this message at 05:15 on Dec 14, 2021 |
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Dec 14, 2021 05:12
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Ok so the raspberry pi is hooked up to the upstream USB hub port and only devices are supposed to be plugged into the downstream ports. So even if the power wires weren't a concern, I don't think I could get a host on a downstream port to talk to a device on a different downstream port of the USB hub. Well, thanks to this thread, I can be pretty sure it wouldn't have worked without having to unknowingly risk my laptop and microcontrollers.  I had no idea there was all this semantic stuff involved with usb ports and sizes. I just thought they were randomly sized for spacing reasons. I found an article talking about the "roles" of different usb ports mentioned earlier. Intruiging.
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Dec 14, 2021 05:19
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Oh yeah, there are probably few too many USB connectors designed (I haven't even seen half of them in person myself), but they at least all have well-defined purposes in the standard - even if people don't always follow the standard. It's good you asked because yeah, that wouldn't have worked at best and would have caused damage at worst. That's why I'm so annoyed by people who don't follow the standard and leave dangerous cables on the store shelves or laying around for people to do ill-advised things with. So (standard) hosts with USB A ports can only ever talk to (standard) devices with USB B receptacles. There is only ever one host on the bus. There is never any situation where you can have a hub with multiple hosts on it at a time. USB On-The-Go allows role switching between host and device (commonly allowing a phone or tablet to be able connect to a computer to access the files on it, and be able to connect to devices like printers, card readers, etc. through the same port.) But it still only allows one host at a time on the whole bus, and the device will pick if it acts as a host or a device based on how it's plugged in. It also requires the use of a standard cable or adapter that has a full-size A receptacle on one side and a micro-B plug on the other. A hypothetical device that claims to support USB OTG and uses an A to A cable for the job is massively non-standard. My USB knowledge predates USB C so I don't know how it works if you plug two hosts together. I would hope that they made sure that while it wouldn't work, it wouldn't fail catastrophically either. But that would also require both devices to follow said standard 
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Dec 14, 2021 05:48
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