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First Time Caller posted:
This is the reason I switched entirely to SMD except for special cases, a little more precision required in assembly but a fair bit cheaper for otherwise identical designs. The ability to do double sided loadouts also helps a lot on board size.
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Sep 5, 2016 18:05
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And, honestly, with a bit of practice, SMD is way easier and faster because you don't have to keep flipping the board around or hold components on while you solder.
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Sep 5, 2016 18:44
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There's a few cases where PTH makes more sense; connectors are always more rugged in PTH, and linear voltage regulators take up more room and are more complicated thermally with SMD versions. I've used one or two 7805 D2PAK for hobbyist projects, but most of the time the through hole version is a better choice.
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Sep 5, 2016 18:57
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First Time Caller posted:* Check your footprints for hidden pins. Maybe this is a KiCad thing but you can set pins to 'Hidden'. People do this for VCC and GND most commonly. However in my design, VCC is 9V and I was using the net label 5V_PWR for regulated power via a 7805. Almost fried the shift registers until I realized why they were getting hot. I have never seen a case where hidden power pins made a design clearer and it falls apart in your situation. I just don't use them, ever. Same with splitting the power pins out of the part and putting them in the power section of the schematic. It just makes it harder to see what is going on. I think/hope both those practices are becoming relics of the past, it's stuff I see on schematics from 1988.
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Sep 5, 2016 18:58
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taqueso posted:I have never seen a case where hidden power pins made a design clearer and it falls apart in your situation. I just don't use them, ever. Same with splitting the power pins out of the part and putting them in the power section of the schematic. It just makes it harder to see what is going on. I think/hope both those practices are becoming relics of the past, it's stuff I see on schematics from 1988. Multi part symbols with a separate power block are super useful IMO, we try to do them that way whenever it makes sense at work. The signal flow and function usually becomes more clear with a nice clean symbol and all the power stuff down in the corner, very useful for logic gates and opamps. With opamps it's particularly useful since a LOT of people have built a board where they flipped the opamp symbol but forgot to flip the power connections (I know I've done it, though only for one home project). It's also basically required for large packages like DSPs and FPGAs. My most hated symbol is the monolithic quad opamp, it's easy to draw the symbol but any schematic drawn with them is guaranteed to be unreadable.
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Sep 5, 2016 19:09
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First Time Caller posted:
Another lesson I learned after getting my first boards back (which you can kinda-sorta see in that nixie gif) was remember to add loving holes for screws so you can actually attach it to things, I have no idea how i'm going to keep my nixie clock in one place now  e: there's like one spot with nothing but uninterrupted ground plane I could drill through, is that a terrible idea?
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Sep 5, 2016 20:18
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longview posted:Multi part symbols with a separate power block are super useful IMO, we try to do them that way whenever it makes sense at work. Those are fine, as long as it has a power block that makes it clear which part they are for. I was thinking of schematics with lone pins just hanging out by the DC-DC converter. I'll try to post an example when I'm at work tomorrow.
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Sep 5, 2016 21:22
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Parallel Paraplegic posted:
Be EXTREMELY careful around the dust you generate with any cutting or drilling. Get a good quality mask and vacuum thoroughly after you're done. Also make sure whatever you connect to is insulated or okay making intermittent contact to your ground. Or just get some dual lock, Velcro, or double sided tape and call it a day.
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Sep 6, 2016 02:43
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You can’t hold it in channels on two sides?
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Sep 6, 2016 03:01
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Platystemon posted:You can’t hold it in channels on two sides? That's how I'd do it with that layout. It's a pretty board, no need to punch holes for hardware. Hold it vertically for all to see. ::edit:: my bad, forgot whose board was whose. sharkytm fucked around with this message at 03:28 on Sep 6, 2016 |
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Sep 6, 2016 03:04
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KnifeWrench posted:Be EXTREMELY careful around the dust you generate with any cutting or drilling. Get a good quality mask and vacuum thoroughly after you're done. Platystemon posted:You can’t hold it in channels on two sides? I guess I should explain a bit more, it's actually four boards (each digit gets its own board, so they're modular and you can just replace the entire board if one blows), connected by edge connectors, that all have to be held flat against the bottom of the enclosure (which I'm making out of acrylic, but might make some of the case out of sheet aluminum just to try to do something about the massive amounts of EMI this thing's boost converter gives off) If they're not held tight enough down, the edge connectors kinda bend them a few degrees due to them not lining up quite right, which makes the digits crooked. Thanks for warning me about drilling though, I've drilled some unrelated copper clad FR4 before and had a vacuum running next to the drill press the whole time to suck the dust away but didn't think of a dust mask, hope I didn't just kill myself  sharkytm posted:That's how I'd do it with that layout. It's a pretty board, no need to punch holes for hardware. Hold it vertically for all to see. I agree this would work great for First Time Caller's board, but my nixie board needs to be horizontal, anchored to the bottom, because the tubes come up at a right angle to it for displaying vertically.
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Sep 6, 2016 03:16
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i want to control 3kW immersion heaters (on 16A/240VAC mains) using a microcontroller so far my spelunking in electronics has led me to some kind of relay or 2, since there's a "boost" coil that can be manually switched on, exclusively to the "off-peak" one that is switched on by a timer, usually. Both coils have thermostatic protection so they'll shut off once they hit the required temp, regardless of applied current. Is there a way that's intrinsically safe to ensure that when I press "heat" in homekit i don't burn down the building? How do you test these things w/o actually hooking them up to real loads? Thanks and god bless
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Sep 6, 2016 14:30
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Malcolm XML posted:i want to control 3kW immersion heaters (on 16A/240VAC mains) using a microcontroller What are these going to be used for? Also, are you sure that protection mechanism is meant for actual regular duty use and isn't just an emergency shutdown to prevent damage? I don't know if I'd rely on it to turn off the thing on a regular basis.
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Sep 6, 2016 14:41
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Parallel Paraplegic posted:What are these going to be used for? Also, are you sure that protection mechanism is meant for actual regular duty use and isn't just an emergency shutdown to prevent damage? I don't know if I'd rely on it to turn off the thing on a regular basis. It's my water heater and that's pretty much what it's been doing for the last 5 years. It has a lovely controller hooked up already that supports such things as daylight savings time and boost button support (TM) . The timer comes on for an hour and heats up the tank to the set temp and stops which usually only takes like 20min I'm in the UK so idk what regs there are
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Sep 6, 2016 15:09
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Well as someone pointed out to me a while back, DIY projects involving mains power is basically an insurance adjuster's wet dream and if it's even in the same room as a fire you might get screwed for it. However, there are premade UL/CE approved boxes that you can install and then control with an external signal wire, I'll dig one up in a sec e: something like this, though this one only controls a single load I think: http://www.ebay.com/itm/like/222186646833?lpid=82&chn=ps&ul_noapp=true You just want something that's a fully enclosed, certified module you just hook up and feed a data signal to, they make plenty of them for controlling electric heaters for HVAC and I'm sure water heaters too. It's literally just a relay in a box but it's a certified box! e2: Two of these might work better actually: http://www.ebay.com/itm/WHITE-RODGERS-24A01G-3-Relay-Electric-Heat/272325269614 Shame Boy fucked around with this message at 15:29 on Sep 6, 2016 |
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Sep 6, 2016 15:14
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Also in unrelated news, seeed is now selling an ESP that does wifi and bluetooth for $6-$7: http://www.seeedstudio.com/ESP3212-Wifi-Bluetooth-Combo-Module-p-2706.html e: Looks like it's sold out already, lol
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Sep 6, 2016 15:23
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Parallel Paraplegic posted:Well as someone pointed out to me a while back, DIY projects involving mains power is basically an insurance adjuster's wet dream and if it's even in the same room as a fire you might get screwed for it. noice i was gonna ask about insurance and CE and poo poo I'm loathe to gently caress around w/ that since i know just how dickish insurance can be but i want my cell phone to turn on my hot water 1hr before i get up 
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Sep 6, 2016 15:40
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Malcolm XML posted:noice i was gonna ask about insurance and CE and poo poo Also keep in mind that loving around with mains is probably one of those things you'd want an electrician to sign off on or do for you, though I'm really not up to speed on UK law or anything.
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Sep 6, 2016 16:34
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Question for anyone who uses the ESP8266 - I can't seem to get anything to run on my ESP-01 besides Blink. I think it's related to serial, whenever I try to use Serial.begin (I've only tried the Arduino environment so far, though I've tried loading it using various methods like platformio, Arduino IDE, etc) it goes into a reset loop that seems to be caused by the watchdog timer timing out after a few seconds. Anyone had this problem?
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Sep 6, 2016 17:50
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Parallel Paraplegic posted:Also keep in mind that loving around with mains is probably one of those things you'd want an electrician to sign off on or do for you, though I'm really not up to speed on UK law or anything. conveniently someone has done all that bullshit for me at a cheaper price than i could AND it should be CE rated: Secure SSR302
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Sep 6, 2016 18:48
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taqueso posted:I'll try to post an example when I'm at work tomorrow.  I remembered them not being labeled with the component designator, but they are. So I guess my only real complaint is that the power pins are on a different page than the rest of the parts' symbols.
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Sep 6, 2016 22:26
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The official Arduino schematic does that 
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Sep 6, 2016 23:57
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Malcolm XML posted:noice i was gonna ask about insurance and CE and poo poo Why does your cellphone need to do this. There are water heaters that have controllers that adapt to load schedules. Assuming your schedule is not alternating day and night shofts every other week.
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Sep 7, 2016 01:13
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I want to make some wifi-enabled mood lighting. The ws2812b light strips are 5v. Can I just throw some resistors on an esp8266 and call it a day? Run the strips at 3.3V? Just try to send 3.3V control to a 5V module? Is there a different setup that people would recommend? I'm fine with direct-from-china and whatnot, and speed of delivery isn't an issue. I will have 8-12 locations of 1-2m each, so I would like keep cost per unit down to something reasonable.
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Sep 7, 2016 02:42
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5<->3v3 level shifters are like 3 for a dollar on AliExpress. https://www.aliexpress.com/item/Fre...2654716503.html 10x 4-channel shifters on boards, so 40 bidirectional lines total, $2.80
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Sep 7, 2016 07:20
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babyeatingpsychopath posted:I want to make some wifi-enabled mood lighting. The ws2812b light strips are 5v. Can I just throw some resistors on an esp8266 and call it a day? Run the strips at 3.3V? Just try to send 3.3V control to a 5V module? I was going to tell you to check the specs on the strips, because a lot of 5V devices will count a 3.3V input as On. But, I took a look at the WS2812B datasheet and it will not when running at 5V. You want to check VIH and VIL to see what the input voltage thresholds are. On that datasheet, VIH is spec'd as '0.7 * VDD', which works out to 3.5V. But, it says acceptable VDD is 3.5 - 5V, so you could switch to 4V or something and the 3.3V input would work. Since this is just a personal project, you might find that 3.3V works for the control signal, or that 3.3V can power the strip even though it is out of spec. I don't think there is a chance you would hurt the strip giving trying either of those things a try. You can switch from one voltage to another in one direction pretty easily using a non-inverting logic buffer IC that has input thresholds that work with your source. If you don't want to wait for a shipment from china, you should be able to find something from digikey/etc for less than $0.50 at qty 1, but you'll have to pay shipping too. You can actually level shift with a variety of ICs, like logic gates (AND with one side tied high, OR with one side grounded, NOT gate and you reverse your uC's output, double NOT gate, etc) as long as the input thresholds line up. It gets a little more complicated if you want to convert in both directions on the same pin, basically you need a specialized IC that will either automatically detect the direction, or one where you control direction directly with a pin. If you are going from a higher voltage to a lower voltage, you need to also be careful not to exceed the maximum allowed voltage on the input to whatever you are using to level shift. taqueso fucked around with this message at 16:00 on Sep 7, 2016 |
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Sep 7, 2016 15:54
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taqueso posted:
That's still a pretty bad way to do it so I can see why you don't like it. Bonus points for putting the power connections and the part on different pages, we can technically do that with the multi part symbols but I've never seen anyone do it other than FPGAs.
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Sep 7, 2016 16:29
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MRC48B posted:Why does your cellphone need to do this. There are water heaters that have controllers that adapt to load schedules. Assuming your schedule is not alternating day and night shofts every other week. because i can
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Sep 7, 2016 17:54
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I will MASTER the INTERNET of THINGS
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Sep 7, 2016 17:55
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How do you figure out the needed current for a whole bunch of servo motors? Is there anything special youd need to think of or keep in mind?
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Sep 8, 2016 04:05
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If the manufacturer has a stall current listed, multiply that by the number of motors you've got and add 20%. If not, you could get an ammeter and stall the motor yourself and see what happens?
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Sep 8, 2016 07:41
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Thanks! I'm going to need like 500Amps
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Sep 8, 2016 14:10
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ekuNNN posted:Thanks! I'm going to need like 500Amps Fuse them and don’t stall them all at the same time?
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Sep 8, 2016 14:16
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ekuNNN posted:Thanks! I'm going to need like 500Amps ... So by a lot of servos you meant several hundred?
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Sep 8, 2016 14:46
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Parallel Paraplegic posted:... So by a lot of servos you meant several hundred? Yes, 670 to be exact. They don't have to do any hard work or anything though. I plan to control them by daisy-chaining 42 of these boards: https://www.adafruit.com/products/815
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Sep 8, 2016 16:02
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ekuNNN posted:Yes, 670 to be exact. They don't have to do any hard work or anything though. I plan to control them by daisy-chaining 42 of these boards: https://www.adafruit.com/products/815 Are there cases where they all have to move at the same time? Because you could software-limit the max number of servos moving at any particular moment to a reasonable number I guess. e: Though servos draw some current just to hold themselves in a fixed position under load too don't they... hrm
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Sep 8, 2016 17:32
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Parallel Paraplegic posted:Are there cases where they all have to move at the same time? Because you could software-limit the max number of servos moving at any particular moment to a reasonable number I guess. AFAIK that's for steppers; the servos that are usually paired with those boards are just DC motors with step down gears and a potentiometer for position sensing, so when it's not moving it doesn't draw any current.
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Sep 8, 2016 18:22
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I'm looking to build a set of Christmas lights to replicate the ones from Stranger Things. I did a ton of searching around for addressable lights and most of them would have required a ton of modifying and re-wiring to get them to look how I want them to, but I stumbled across a site selling ones that actually look like Christmas lights rather than just an LED strip light. http://www.environmentalled.com/RGB---C9-Opaque-WS2811-Pixels-50-Count-Black-Wire-p2279.html There seem to be a ton of resources out there for making arduino controllers for these things, but they almost all assume that you're familiar with working with Arduino, which I'm not. Because there are tons of libraries out there already for controlling the light strips, I feel like this should be a fairly basic intro to this type of thing, but I'm struggling to find any guide that actually lists out all of the hardware I'll need to make the controller. Realistically I want to be able to plug a computer into them and make a program to be able to turn on and off single lights in a set sequence. It would be nice if it didn't need to be plugged into the computer while it runs. Has anyone worked on this type of project before? Edit: I ended up ordering this starter kit and a 12V, 2A power supply for the lights themselves. https://www.amazon.com/dp/B01D8KOZF4?psc=1 Looking around some more it looks like I might really just have to wire the power supply positive to the lights, the power supply ground to both the Uno board and the lights and then run a wire from the Uno to the data wire on the lights. Is it really that simple? For reference, this is what I was reading. http://www.tweaking4all.com/hardware/arduino/arduino-ws2812-led/ rockcity fucked around with this message at 20:04 on Sep 8, 2016 |
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Sep 8, 2016 18:43
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Steppers will draw a constant current when holding position. A servo theoretically would shut off when it gets to the set point but often will overshoot,reverse direction, overshoot,etc causing it to jitter around the setpoint.
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Sep 8, 2016 18:47
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Parallel Paraplegic posted:Are there cases where they all have to move at the same time? Because you could software-limit the max number of servos moving at any particular moment to a reasonable number I guess. I'm actually planning to add a relay to switch off a row of servos/pixels if none of them need to be updated, because these cheap servos do tend to jitter like peepsalot says. And yes, I was wondering if I could just limit the update rate to one row of servos every x milliseconds to lower the amount of amps needed, but Ive found a good deal on aliexpress for 5v/300A power supplies so the point is moot now I guess Also I was wondering, those adafruit PWM boards say to just power the servos through the first board, but i cant imagine its good practice to daisychain 500A through these little boards? Should i just add in extra power/GND wires every n boards?
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Sep 8, 2016 20:31
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