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Stabby McDamage posted:Do you plan to do a build log somewhere? It would be cool to have a deep dive of a nice, professional-looking project. I might do that after we update it a little bit. The cabling/electronics organisation is a bit of a messy nightmare at the moment because we just had to get it working in the tight deadline and there's over 2km of servo cable involved  We'll re-organise it and update some things so it will be easier to move it to other expositions and stuff in the coming weeks.sharkytm posted:That'll do it. The servo heat is handled by the water, for sure. Do you happen to have an ammeter on it? I'd be interested to see how much it draws during a full black->plastic image switch. I'll bet it's a lot less than you planned, because the servos are not working at max load. I don't have a reading of the whole thing working, but I did test it with a single servo, and it peaks at about 400mA when quickly moving up and down, with about 750mA if you stall it, so for safety I aimed for 1A per servo.
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Nov 6, 2016 15:51
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Jamsta posted:So I keep burning out DC fans, specifically sensored 12v CPU/case fans from PCs when I connect them to my variable DC supply. https://www.youtube.com/watch?v=_3mCpblX7zs To answer your questions: plausibly, and sure. Even 18 V will take a while to overheat the windings. Before that, the hall effect sensor may not be happy with the overvoltage, which could be what happened here.
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Nov 6, 2016 15:54
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Jamsta posted:So I keep burning out DC fans, specifically sensored 12v CPU/case fans from PCs when I connect them to my variable DC supply. So you're saying that the fan is rated for $voltage and you are intentionally putting in $voltage*1.33 and they are burning up, huh  (the windings should be fine, but the motor controller might be a lot more delicate. could be things going on like a voltage divider bringing the 12v supply down to 3.3v to run some kind of logic, and by overvolting the whole thing to 16v you've brought that supply up to 4.4v, which is certainly enough to burn it out. etc)
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Nov 6, 2016 20:46
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Sagebrush posted:So you're saying that the fan is rated for $voltage and you are intentionally putting in $voltage*1.33 and they are burning up, huh Assumptions were my mistake  I had assumed the tolerances wouldn't be so strict, and until I saw BigClive's recent teardown of a computer fan I assumed it was a big dumb motor, with no active electronics. Knew I was doing wrong, but now I'll be more careful.
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Nov 7, 2016 00:20
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Jamsta posted:Assumptions were my mistake I first learned they actually had stuff inside them when I realized you could completely stop them and they'd sit there not trying to run for a second or two and then try to spin up again which is a real neat feature
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Nov 7, 2016 05:33
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So I have a big hunky solenoid that requires ~1.6A at 12V to actuate and I would like to run it off of (ideally) a single 18650. It's only going to actuate for about a second or two, like once or twice a day tops (more like once a week) so i don't think it's too much to ask for ~6A from a good 18650 considering vape dweebs can pull tens of amps out of them. So far I have tried two different boost converters, the most powerful being this one: https://www.amazon.com/gp/product/B00UR5K4AE/ It freaks out and just blinks a bunch and twitches the solenoid. If I use it with two 18650's in series, it works fine, so it's clearly capable of delivering the power, just not from something that low voltage. My questions are: - Is there a boost converter that can actually do what I want? Does it cost $infinity dollars? - Can I modify this boost converter to do what I want? I tried loving around with a less powerful one by putting on a new, faster diode and changing the inductor for a few different values, and it seemed to increase the output a little but not enough. - If no to the previous two, is it at all safe to use two 18650's in series, including charging? Everything I've read says "god no" so I assume that's the answer, unless there's a way to make it safe.
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Nov 7, 2016 18:52
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ekuNNN posted:Thanks guys That's really cool. I guess the grease was enough to waterproof for the shallow depth they operated at (at least for some period of time) without adding too much extra resistance to any moving parts? I'll have to keep this in mind for this project I have in mind for the future, thanks!
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Nov 7, 2016 19:46
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ate all the Oreos posted:So I have a big hunky solenoid that requires ~1.6A at 12V to actuate and I would like to run it off of (ideally) a single 18650. It's only going to actuate for about a second or two, like once or twice a day tops (more like once a week) so i don't think it's too much to ask for ~6A from a good 18650 considering vape dweebs can pull tens of amps out of them. So far I have tried two different boost converters, the most powerful being this one: Are you accounting for inrush current?
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Nov 7, 2016 20:03
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rawrr posted:Are you accounting for inrush current? From the batteries? I'm not entirely sure if I have the tools to actually measure that, but I tried multiple high-discharge 18650's in parallel (i actually have a few of the vape dweeb kind) so unless the thing is trying to draw something like 300A the problem is with the boost converter. If you mean from the boost converter itself, what would solve that - a chunky, low-value resistor in series with the solenoid?
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Nov 7, 2016 22:30
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ate all the Oreos posted:So I have a big hunky solenoid that requires ~1.6A at 12V to actuate and I would like to run it off of (ideally) a single 18650. It's only going to actuate for about a second or two, like once or twice a day tops (more like once a week) so i don't think it's too much to ask for ~6A from a good 18650 considering vape dweebs can pull tens of amps out of them. So far I have tried two different boost converters, the most powerful being this one: This thing says the display doesn't like to work with less than 4 volts. Lithium charges at 4.2 volts, but nominal cell voltage is less than that. Either way you can't expect much at that threshold. Rawrr is right to point out that the inrush current is probably going to be too much for the boost to provide. You want a big capacitor somewhere between your 12 V bus and the switch to the solenoid. This will provide the charge to handle the initial inrush current, which at time zero from flipping the switch is basically a short circuit prior to the establishment of a field interacting with the armature. The holding current is your ~1.6 A. Don't forget to account for the fact that switching off the solenoid will create some inductive kickback. There should be a power resistor and a diode in parallel with the solenoid coil to dissipate this safely.
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Nov 7, 2016 22:32
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Effective-Disorder posted:This thing says the display doesn't like to work with less than 4 volts. Lithium charges at 4.2 volts, but nominal cell voltage is less than that. Either way you can't expect much at that threshold. Yeah the screen blinks out but I figured that's just due to the way the circuit is arranged (probably powering the screen from a linear regulator) and the voltage across the battery drops to ~3.6 but it seems to try to power the solenoid, like I said it clicks and twitches a bit. Effective-Disorder posted:Rawrr is right to point out that the inrush current is probably going to be too much for the boost to provide. You want a big capacitor somewhere between your 12 V bus and the switch to the solenoid. This will provide the charge to handle the initial inrush current, which at time zero from flipping the switch is basically a short circuit prior to the establishment of a field interacting with the armature. The holding current is your ~1.6 A. Don't forget to account for the fact that switching off the solenoid will create some inductive kickback. There should be a power resistor and a diode in parallel with the solenoid coil to dissipate this safely. Thanks, I'll go ahead and see if a capacitor makes a difference. I've got the safety circuitry in place for the inductive kickback already, learned that lesson a long time ago after frying something
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Nov 7, 2016 22:38
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This isn't really the thread I was looking to find to ask this specific question however, here goes... I'm looking for a Kill-A-Watt style watt/hour meter however, the one I've got right now only goes to a single decimal in total kw/hr, and I'd like one that's accurate to at least 3 decimals places and which can still be plugged into standard american appliance outlets. I looked around online and it was more effort than I expected to find something as simple as that out, so I figured someone in here has probably tried and tossed a few and might have some experienced opinions. I am using it specifically and mainly for energy auditing, because I'm taking some classes on home energy auditing and I'm still using pretty simple tools and calculations but would like something better than this loaner kill-a-watt, to figure out just how much something uses over a certain period when its demand fluctuates, etc.. Bonus points if there's a way to set it to ONLY record how much flow goes through during a timed period (I dunno, an on-device timer, or a cheapo device which can plug into a laptop to program, I'm assuming), and if it's less than like $50 because I'm just a poor student coyo7e fucked around with this message at 02:53 on Nov 8, 2016 |
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Nov 8, 2016 02:50
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coyo7e posted:This isn't really the thread I was looking to find to ask this specific question however, here goes... I'm looking for a Kill-A-Watt style watt/hour meter however, the one I've got right now only goes to a single decimal in total kw/hr, and I'd like one that's accurate to at least 3 decimals places and which can still be plugged into standard american appliance outlets. I looked around online and it was more effort than I expected to find something as simple as that out, so I figured someone in here has probably tried and tossed a few and might have some experienced opinions. Watts are joules/second. Watts represent power, that being energy/time. You're thinking of (kilo)watt • hours, which ultimately add up to a certain number* of joules of energy. Since most electrical power costs an average of around 12 cents per kilowatt hour in the US, dividing beyond that doesn't tell you much about cost unless you're scaling out a bit. That's probably why you won't quickly find consumer devices that measure power consumption beyond a certain precision. People typically take the average power and integrate, while you want to get real time consumption history. I did a quick search and found some leads you might find useful: https://hackaday.com/tag/kill-a-watt/ Chances are you're going to need to do something like whatever hackery they're doing to do your data logging, or find a product that offers logging on the level of a smart meter or some-such. I really should have done something like that for my senior design project, with IoT and crap. I might have a job by now if I wasn't so set on building toys. Oh well. Ultimately, if you can find a cheap power measurement tool with a digital bus, you can hook up a micro-controller and send the data somewhere so that you can get charts of consumption in real time. Or you can buy something that already does that. I don't know about stuff that already does the latter, but I can tell you that other people have done the former as seen in the link. Edit: * 1 kWh = 1000 x 1 J/s x 60 s/m x 60 m/h x 1 h = 3,600,000 J Effective-Disorder fucked around with this message at 03:57 on Nov 8, 2016 |
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Nov 8, 2016 03:47
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Well adding a (really big) capacitor helped, it actually retracts now, but the force it retracts with is pretty weak and even a slight amount of friction keeps it from retracting. If I up the boost converter to 20V the capacitor's charge seems to be enough to forcefully yank the solenoid back but that's a good 8V above what it's supposed to be driven at. Like I said previously, the whole thing seems to work fine if I can just double the input voltage. Anyone know where I can get a lithium ion series battery that doesn't, uh, explode
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Nov 8, 2016 05:56
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ate all the Oreos posted:Well adding a (really big) capacitor helped, it actually retracts now, but the force it retracts with is pretty weak and even a slight amount of friction keeps it from retracting. If I up the boost converter to 20V the capacitor's charge seems to be enough to forcefully yank the solenoid back but that's a good 8V above what it's supposed to be driven at. Like I said previously, the whole thing seems to work fine if I can just double the input voltage. Anyone know where I can get a lithium ion series battery that doesn't, uh, explode The solenoid probably won't have problems being driven at 20 V if you're only using it every now and then. What ultimately kills a solenoid is a short circuit, when the insulation between turns in the coil breaks down and current can jump across turns. Heat can cause the insulation to break down. Heat is a function of current and resistance. Ultimately, you need a certain amount of current to produce the required magnetic flux to yank the armature. Regardless of whether that's coming from a boost module at "20 V" or just 3 or 4 lithium cells in series, the force you need will always be a function of the current through the solenoid. Given that it's a cheap boost converter made by whoever, for all you know the "20 V" is actually 12 V output and the boost converter is a piece of crap to begin with, unless you've actually taken measurements. Either way, your solenoid will probably not fail before the questionable boost module. If you're really concerned, invest in test equipment. Acceptable multimeters and infrared thermometers are attainable for $20 a pop. Edit: Also, you can haze the makers into giving you better answers, since they know how they built the thing. I can't see poo poo under the heatsink in the photo. http://www.droking.com/forums/forum/voltage-regulator-support/ Effective-Disorder fucked around with this message at 06:53 on Nov 8, 2016 |
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Nov 8, 2016 06:48
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ate all the Oreos posted:Well adding a (really big) capacitor helped, it actually retracts now, but the force it retracts with is pretty weak and even a slight amount of friction keeps it from retracting. If I up the boost converter to 20V the capacitor's charge seems to be enough to forcefully yank the solenoid back but that's a good 8V above what it's supposed to be driven at. Like I said previously, the whole thing seems to work fine if I can just double the input voltage. Anyone know where I can get a lithium ion series battery that doesn't, uh, explode How big is this “really big” capacitor? I ask because I considered suggesting “add a shitload of capacitance”, but then I did the mental arithmetic for how much I thought you’d need (hundreds of mF), and capacitors of that size are kind of big and pricey. Back‐to‐back sketchy boost converters would probably work (each multiplying the voltage by the same factor), if the lithium cell can handle the increased inefficiency. Platystemon fucked around with this message at 07:00 on Nov 8, 2016 |
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Nov 8, 2016 06:52
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Effective-Disorder posted:The solenoid probably won't have problems being driven at 20 V if you're only using it every now and then. What ultimately kills a solenoid is a short circuit, when the insulation between turns in the coil breaks down and current can jump across turns. Heat can cause the insulation to break down. Heat is a function of current and resistance. Ultimately, you need a certain amount of current to produce the required magnetic flux to yank the armature. Regardless of whether that's coming from a boost module at "20 V" or just 3 or 4 lithium cells in series, the force you need will always be a function of the current through the solenoid. Given that it's a cheap boost converter made by whoever, for all you know the "20 V" is actually 12 V output and the boost converter is a piece of crap to begin with, unless you've actually taken measurements. Yeah I have plenty of test equipment lol. The boost converter absolutely is a piece of crap but it does seem to be outputting the voltage it claims it's outputting, at least until the solenoid is connected and it starts struggling. I know that the solenoid force is driven primarily by current but that can't be the only thing right? I tried putting a high current at a lower voltage through it thinking maybe I could ignore the converter altogether and it didn't budge. Didn't even start trying to move until around 6V.
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Nov 8, 2016 06:55
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Solenoids are ohmic, so you need enough voltage to flow the required current to produce the requisite force. But it's not as simple as just measuring the resistance of the coils. When a solenoid is active, the impedance is a combination of both electrical resistance and magnetic reactance, and mostly the latter. There are equations to calculate the effective impedance of a solenoid based on the coil parameters and the input voltage; that will tell you what voltage you need to hit some level of force. I can't remember them, but you can look them up online.
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Nov 8, 2016 07:13
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ate all the Oreos posted:Yeah I have plenty of test equipment lol. The boost converter absolutely is a piece of crap but it does seem to be outputting the voltage it claims it's outputting, at least until the solenoid is connected and it starts struggling. I know that the solenoid force is driven primarily by current but that can't be the only thing right? I tried putting a high current at a lower voltage through it thinking maybe I could ignore the converter altogether and it didn't budge. Didn't even start trying to move until around 6V. Magnetic field strength is driven by current (and solenoid length/turns, but that's fixed). How much field (thus current) you need depends on the force you need your solenoid to exert. You'll see a difference over time as the armature moves, or if you pull on it, and so on. What Sagebrush says applies heavily here. Did you measure the current and voltage simultaneously during your test? Like, using two meters? Your boost converter is a piece of crap, but if you set it for 20 V and it works, then it will work until the boost converter shits the bed. I think this is a better solution for you than dealing with charge balancing and multiple cells, unless you have some kind of aversion to burning a cheap boost converter if that even ever happens with whatever intermittent use you have in mind. There are ways to go if you want to increase your battery voltage by adding cells, but I think it's a waste of time if you already have a solution that isn't releasing magic blue smoke yet. Effective-Disorder fucked around with this message at 07:36 on Nov 8, 2016 |
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Nov 8, 2016 07:32
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Effective-Disorder posted:Magnetic field strength is driven by current (and solenoid length/turns, but that's fixed). How much field (thus current) you need depends on the force you need your solenoid to exert. You'll see a difference over time as the armature moves, or if you pull on it, and so on. Well it's ultimately going in a box and being shipped to a friend so I'd rather it not die immediately or catch fire. I'm fine with getting a better boost converter (though I'm not really sure where to get it or how to know if it's not crap) or a pre-assembled battery pack that can handle charging for me. I found this on Amazon, meant for self-heating winter coats which are apparently a thing: https://www.amazon.com/Gerbings-Gyde-Spark-extended-Battery/dp/B01LXTP2A7 I'd rather get something that's not $50 though.
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Nov 8, 2016 07:37
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Sagebrush posted:Solenoids are ohmic, so you need enough voltage to flow the required current to produce the requisite force. But it's not as simple as just measuring the resistance of the coils. When a solenoid is active, the impedance is a combination of both electrical resistance and magnetic reactance, and mostly the latter. Ah ok, figured it was some kind of equivalent resistance situation going on, thanks.
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Nov 8, 2016 07:39
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ate all the Oreos posted:Well it's ultimately going in a box and being shipped to a friend so I'd rather it not die immediately or catch fire. I'm fine with getting a better boost converter (though I'm not really sure where to get it or how to know if it's not crap) or a pre-assembled battery pack that can handle charging for me. I found this on Amazon, meant for self-heating winter coats which are apparently a thing: https://www.amazon.com/Gerbings-Gyde-Spark-extended-Battery/dp/B01LXTP2A7 The battery is usually what causes horrible fires. Still, don't trust anything you read on Amazon is the lesson, I guess. If it was me, I'd take pains to make it catch fire under controlled conditions first, so that I know where and when that happens before I trust any of my friends with it. Unless, of course, I wanted to set my friends on fire, which seems like a bad thing. The total power output of the converter as you've laid it out doesn't seem to exceed the claimed maximum for the converter, but you do get a voltage drop under load, which suggests that the converter is having trouble keeping up. We've seen some suggestions: 1. Add more input voltage with a battery pack. 2. Cascade boost modules. 3. Just up the output voltage setting and let it handle the drop as best as it can. You've tested out #3, and it seems to have worked so far, so my suggestion was to just keep testing #3 and save your money until you see how that goes. But, it now seems that you might set your friend on fire. So, perhaps you are to rethink your plans? I can't give you enough advice to absolutely ensure you don't set your friend on fire, so in the end my advice is to do nothing, and avoid any chance of setting anyone on fire. Either way, good luck to you.
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Nov 8, 2016 08:15
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I'd just get two 18650's in series in one of these holders. In fact, having a number of 18650s in series in a holder is how I power almost all my nonsense nowadays.
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Nov 8, 2016 17:07
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Stabby McDamage posted:I'd just get two 18650's in series in one of these holders. In fact, having a number of 18650s in series in a holder is how I power almost all my nonsense nowadays. Yeah I have plenty of 18650 holders like that (though with mine you have to explicitly wire the two together so it can be either series or parallel) but isn't that dangerous to charge? Is there a good solution for charging something like that or am I going to have to ship my friend a little battery charger too so he can take the batteries out and whack em' in the charger periodically? Can I do something weird like normally have the batteries independent and charge them separately using two different charging boards, then use some MOSFETs or a relay or something to put them in series for actuating the solenoid?
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Nov 8, 2016 17:15
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Just get 4 batteries: an in-use pair and an on-charger pair. You can get 2- or 4-bay chargers for 18650s cheap on ebay; each bay is a separate charge/status circuit, so they're easy to use. You leave the charger plugged in somewhere, and every once in a while you just swap em.
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Nov 8, 2016 21:21
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I have come up with a better idea that I didn't think of because I am An Idiot: I bought a less powerful solenoid that should still work fine but require half the amps 
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Nov 8, 2016 21:28
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ate all the Oreos posted:I have come up with a better idea that I didn't think of because I am An Idiot: I didn't think of that either, and I put my pants on the same as anyone else: One leg on my head, and the other on my arm. Either way, your conclusions were basically on par with mine, as far as possible steps to take. I think you have your head put on at least as straight as I do, if that's saying anything positive. I'm not a genius, and I have never stayed at a Holiday Inn Express. You're obviously not an idiot. An idiot would have used a car battery from the word 'go'. Hopefully your new solenoid works well. Just out of curiosity, what are you trying to do with the solenoid anyway?
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Nov 8, 2016 22:07
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Effective-Disorder posted:I didn't think of that either, and I put my pants on the same as anyone else: One leg on my head, and the other on my arm. Either way, your conclusions were basically on par with mine, as far as possible steps to take. I think you have your head put on at least as straight as I do, if that's saying anything positive. I'm not a genius, and I have never stayed at a Holiday Inn Express. You're obviously not an idiot. An idiot would have used a car battery from the word 'go'. It's going to be the latch on a ~mystery box~ that can be unlocked remotely (like very remotely, I'm putting a GSM modem in it because i had one laying around I was playing with a while back so why the gently caress not ) and then after that I guess it will just be a regular box with a fancy latch
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Nov 9, 2016 00:57
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So, I'm wondering if I hosed up. I'm putting in some under cabinet lights, so I purchased these: https://www.amazon.com/gp/product/B005GL5R56/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1 I needed a transformer that was compatible with Insteon 120v dimmers, so I went with this: http://www.mouser.com/ProductDetail/Mean-Well/PCD-25-1400A/?qs=%2F%252bo%2FYLy8OFqTElfaZLVxRg%3D%3D It seems to work fine, but I noticed the LEDs get really hot (after being on for about an hour, they got up to 180F). Checking with a meter, they're getting about 17 volts. Did I screw up by getting a 12-18 volt power supply, or are these meant to be driven at 17V? They're self-adhesive so I just stuck them to the underside of the cabinet... did I need a heatsink?
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Nov 10, 2016 03:04
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Yup, you screwed up. They're 12V only, because they have onboard resistors to limit current. If you give them more voltage, it all turns into heat. I'm not sure what product you could get that would let you dim them with a commodity dimmer - I've only down it with actual LED strip controllers (or a custom circuit involving a MOSFET and a microcontroller). EDIT: They make in-wall dimmers specifically for 12V LED strip, but you'd still need a separate 12V DC PSU, which would run into and out of this dimmer to the strip itself. Not sure if that's what you want. Example.
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Nov 10, 2016 04:24
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It looks like that Mean Well power supply he bought has a variable output voltage. Page 4 of the data sheet says you need to put a Triac based dimmer on the input in order to adjust the output voltage and even gives some model numbers of dimmers which will work.
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Nov 10, 2016 05:07
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DethMarine21 posted:It looks like that Mean Well power supply he bought has a variable output voltage. It's 12-18v. This is the 8-12v version which covers the useable range of those led strips.
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Nov 10, 2016 06:05
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Has anyone seen any project that would allow one ESP8266 to reflash another? I'm having trouble googling the concept... Basically we're programming ESP8266's using the Arduino IDE in C for remote sensor applications, and we'd like to be able to update their firmware with a second "rescue" ESP8266.
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Nov 10, 2016 16:53
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MisterOblivious posted:It's 12-18v. This is the 8-12v version which covers the useable range of those led strips. Thanks, that looks like exactly what I need! I'm not too worried about dimmer compatibility, the one I have seems to dim fine with the Insteon dimmer I have.
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Nov 11, 2016 01:12
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Stabby McDamage posted:Has anyone seen any project that would allow one ESP8266 to reflash another? I'm having trouble googling the concept... Report back if you find anything, that's a good idea. There already exist OTA bootloaders (good Google term), but chances are you know that. They require your program to take up less than half of the available flash memory, though, which is a deterrent. If you don't find anything, you can port the important parts of the ESPTool to C++. https://github.com/espressif/esptool/blob/master/esptool.py It shouldn't be particularly hard, just a lot of work, which is an unnecessary pain in the dick if something already exists.
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Nov 11, 2016 02:14
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ante posted:Report back if you find anything, that's a good idea. Thanks. I saw the half-flash OTA method, but it seemed complex, and I'm trying to avoid complexity, as students are the ones doing this work.
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Nov 11, 2016 05:23
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I also have a combination physics/electronics question. I put an accelerometer on a turntable (literally a record player) and recorded acceleration. What I expected to see is a small near-constant acceleration due to centrifugal force, but instead I see a sine wave with the same frequency as the turntable's rotation rate (plus a slight constant offset, which I'm interpretting as the centrifugal force). I have no idea where the sine component would come from, except perhaps for an idiosyncracy of the accelerometer module maybe? Anyone have any idea there? To be clear, the sensor is rotating along with the turntable, not translating in a circle (in which case I'd expect the sine wave). Stabby McDamage fucked around with this message at 05:29 on Nov 11, 2016 |
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Nov 11, 2016 05:26
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Stabby McDamage posted:I also have a combination physics/electronics question. if the turntable is belt driven the belt may be acting as a spring. e: nevermind I misread and thought it was oscillating during the spin-up, which is where I would expect a belt to possibly contribute a sine component. e2: oh wait i got this riddle. the turntable is not level with respect to earth's gravity e3: comedy option, its turntables all the way down peepsalot fucked around with this message at 05:45 on Nov 11, 2016 |
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Nov 11, 2016 05:32
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Stabby McDamage posted:I also have a combination physics/electronics question. Okay, getting the obvious out of the way: you're not measuring z, are you? You could be seeing periodic imperfections/imbalance.
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Nov 11, 2016 05:43
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Are you only looking at the x dimension, the scalar magnitude of the xyz vector, or all 3 component vectors? Maybe if the record was tilted you'd see the total fluctuating as gravity moves around.
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Nov 11, 2016 05:49
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