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I built a board with eight purple LEDs hooked up to a CR2032 through 470 ohm resistors, and they were still lit up a month later, blew my mind I'd guess I'm discharging the battery way past the rated lifetime, combined with low current draw the entire time, makes for unexpectedly good results. But yeah, you should be fine for a while with the flashing light.
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Sep 26, 2018 18:52
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ante posted:I built a board with eight purple LEDs hooked up to a CR2032 through 470 ohm resistors, and they were still lit up a month later, blew my mind The only reason I'm a little curious as to the actual current draw is that it's a white flickering LED, so you're already pretty close to the forward voltage of a white LED with 3.0V and the flickering circuitry may or may not be drawing a bunch of current too... According to the page linked from the video, the forward voltage is 2.7V and the current (I assume max current but it just calls it "DC forward current") is 30mA. In the video, she doesn't add a resistor, just tapes the LED to the CR2032 and relies on its internal resistance to current limit. If I were you I'd definitely put a resistor in series with it, but the trick is gonna be finding a resistor that limits the current to a reasonable amount but still allows the flicker circuitry to run.
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Sep 26, 2018 19:01
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ate all the Oreos posted:If you have a multimeter you can check the current it uses (unless the current is too low to be measured by your multimeter, cheap ones might not be able to read it) and then calculate about how long the battery will last using the milliamp-hours rating of the battery. A quick google says it's 235mAh for CR2032's made by Energizer, which is probably not gonna vary much between brands. lol I'm here asking how long a masking-taped LED will be powered by a naked battery. You think I have a multimeter?  It's a CVS brand battery. I was going for cheap.
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Sep 26, 2018 19:40
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Mr. Powers posted:Also, as a note, I'm pushing this at work, but I want it to spread beyond. W.fl is pronounced "waffle". Keep this spreading across the electronics industries. Consider me converted.
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Sep 26, 2018 21:33
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I made a thing in college that had a single 5 millimeter orange LED powered by a cr2032, drawing like 10mA when I first turned it on. we put it in a display case, and I expected the battery to run out in a few days, a week tops, and that's what apparently occurred about three months later I happened to be walking by the display case after the building was closed, while all the lights were off, and I noticed a faint orange glow still coming from the device. Things couldn't have been drawing more than a tenth of a milliamp, but it was still going. Those coin cells apparently have very long tails
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Sep 27, 2018 03:57
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You can use a joule thief the drain the battery all the way. It will boost from a really low voltage. Not sure what the efficiency is like. https://en.wikipedia.org/wiki/Joule_thief
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Sep 27, 2018 06:01
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There's reason the 2N3904 and 2222A are still made, they have perfectly adequate performance, bandwidth etc. for what people use them for. And industrial inertia means those parts are at least triple sourced in almost any package you want, making them an extremely safe bet for long lived products. A lot of the specialized high performance bipolars are disappearing, try getting a 20V+ rated RF PNP transistor these days for example. Dual-gate MOSFETs are also sadly dying, I suspect Renesas is pretty much the only manufacturer that will continue making them since a ton of Japanese radio designs use them as cheap mixers and AGC amps but NXP is killing their models off one by one.
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Sep 27, 2018 16:29
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Yeah I absolutely have SOT-23 2N3904s scattered all over my desk, workbench, the cracks in the floor, probably stuck in my beard, etc. I should just buy a fuckin reel.
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Sep 28, 2018 03:49
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longview posted:There's reason the 2N3904 and 2222A are still made, they have perfectly adequate performance, bandwidth etc. for what people use them for. I got bit when ON Semi stopped making an oddball part: a PUT, specifically the 2N6028. I bought 400+ of them from Mouser and Allied, and then Central Semi started making them again... Whatever, I've got enough to last until the end of time with my consumption of 4-6/year.
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Sep 28, 2018 04:14
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sharkytm posted:I got bit when ON Semi stopped making an oddball part: a PUT, specifically the 2N6028. I bought 400+ of them from Mouser and Allied, and then Central Semi started making them again... Whatever, I've got enough to last until the end of time with my consumption of 4-6/year. wow pricy
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Sep 28, 2018 04:33
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I love hearing about oddball parts. What do you use them for?
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Sep 28, 2018 04:36
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shovelbum posted:wow pricy Hardly, I got 300 from Allied for $0.157/each. Under $50 to never have to worry about it again is cheap insurance. I think I paid under $.50 each for the 100 that Mouser had. Now, Central wants like $1.50/each. Aurium posted:I love hearing about oddball parts. What do you use them for? I can't get into the details, but it's used in a flyback converter circuit to generate 350VDC from 24VDC. It's an archaic design, but very reliable. The old version used a Neon tube... so at least we've moved beyond that.
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Sep 28, 2018 05:10
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sharkytm posted:Hardly, I got 300 from Allied for $0.157/each. Under $50 to never have to worry about it again is cheap insurance. I think I paid under $.50 each for the 100 that Mouser had. Now, Central wants like $1.50/each. Oh nice, ground floor. What do you guys buy by the reel for just "stock"?
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Sep 28, 2018 05:16
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You can buy a reel of resistors for like $50
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Sep 28, 2018 05:46
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Foxfire_ posted:You can buy a reel of resistors for like $50 Some of em are like 10 buckaronies for a reel! Hey if I want to put red LEDs in my beard to look satanic what should I do for wire, like beard colored wire wrap wire or is there a good multiconductor solution or what edit: I HAVE BINDERS FULL OF RESISTORS
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Sep 28, 2018 06:15
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shovelbum posted:Some of em are like 10 buckaronies for a reel! 26-28 gauge magnet wire, you don't need anything fancy or high current for a few LED's so just get stuff that's small and easily disguised and shaped
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Sep 28, 2018 06:17
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ate all the Oreos posted:26-28 gauge magnet wire, you don't need anything fancy or high current for a few LED's so just get stuff that's small and easily disguised and shaped yeah I did it with some 30ga kynar I think thats the best bet
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Sep 28, 2018 06:23
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What's the goon consensus on lead-free solder?
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Sep 28, 2018 17:27
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Sucks If you're not a production facility, just use lead. And don't lick it. Or at least, not chronically for thirty years
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Sep 28, 2018 18:12
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Lead-free is fine but leaded solder is nicer. It flows better, wets joints better, proves good joints by turning shiny, and uses gentler flux. Get the 63/37 eutectic mixture. However, those are all relatively subtle differences, and lead-free solder is perfectly fine for nearly everything. Consider that all of the electronics you've bought in the last decade or more are made entirely with lead-free. Note that lead-free solder is still allowed to contain a small amount of lead (up to 0.1% by law, probably more if you buy cheap stuff) so you still shouldn't eat it.
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Sep 28, 2018 18:28
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Kester eucetic all the way. Lead free never looks as good, and the higher temps are annoying to deal with for rework (like using desoldering braid).
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Sep 28, 2018 18:52
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63/37 eutectic with the least harmful flux u can find, because it's the flux vapors that are likely to gently caress you up
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Sep 28, 2018 19:04
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Even cheap 60/40 AliExpress lead solder is miles better than anything but the most expensive lead-free in my hobbyist experience.
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Sep 28, 2018 19:07
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Silver solder is nice and comparable in my experience, but expensive. Again, though, there is literally no reason for a hobbyist to go lead free. Just wash your hands, it won't hurt you.
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Sep 28, 2018 19:55
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The only people really at risk from lead exposure are kids, because even sustained exposure to minuscule amounts has big effects on their squishy child brains. If your kid likes to hang around and watch you / help you solder, make sure they wash their hands after and maybe get an air filter fan, they're pretty cheap. I have one because my wife hates the smell of flux smoke, and it works surprisingly well for what's effectively just "a fan with some carbon-y foam in front of it". And yeah as other posters pointed out the burning flux is, well, smoke. Breathing smoke is probably not great for you regardless of what the smoke is made of. It's a shame because I really like the smell of rosin flux burning cuz I grew up hanging around my dad soldering 
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Sep 28, 2018 20:49
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Yeah...my attitude to it is basically "smoke is smoke." Flux vapors aren't good for you, no, but if it's rosin flux it's literally just clarified pine tar, and a temperature-controlled iron isn't hot enough to vaporize lead (no, get out of here, Maxwell and Boltzmann!). It's not really any worse for you than standing around a smoky campfire. I'll deal with it. e: be careful though! some other fluxes are SUPER NASTY, particular the acid/chloride fluxes used in plumbing and such. you definitely don't want to be breathing that poo poo
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Sep 28, 2018 20:56
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I've only ever used 63/37. I'm glad I made the right choice. What's the safest flux? The literature is oddly unspecific, the categories overlap, and there are Opinions. e: Also it looks like carbon filters suck: Measurement of the Performance of Air Cleaners Against the Particulate Element of Rosin-based Solder Flux Fume. I'm still going to use one for the non-particulate stuff. Normal Barbarian fucked around with this message at 21:15 on Sep 28, 2018 |
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Sep 28, 2018 21:05
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ate all the Oreos posted:The only people really at risk from lead exposure are kids, because even sustained exposure to minuscule amounts has big effects on their squishy child brains. If your kid likes to hang around and watch you / help you solder, make sure they wash their hands after and maybe get an air filter fan, they're pretty cheap. I have one because my wife hates the smell of flux smoke, and it works surprisingly well for what's effectively just "a fan with some carbon-y foam in front of it". I'm obliged to throw in women who are pregnant or are likely to become pregnant soon in the lead exposure risk pool.
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Sep 28, 2018 21:47
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 Lead is dangerous? Hold my cigar.https://www.youtube.com/watch?v=jQ_85fp1avs
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Sep 28, 2018 22:26
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Collateral Damage posted:
hell yes i've been looking for this forever. i always want to show it when i'm demoing how to use bondo and students ask me if it's toxic "oh, sure it is. but hey, until we invented bondo, you just had to trowel on molten lead with a torch until all your teeth fell out"
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Sep 28, 2018 22:32
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"Well when they took th' mercury out of it it wouldn't work good" 
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Sep 28, 2018 22:33
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It's not like lead free solder is particularly hard to work with or anything. Hobbyist stuff is just as likely as commercial stuff to end up in a landfill leaching into groundwater, so use lead free.
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Sep 29, 2018 06:13
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Foxfire_ posted:It's not like lead free solder is particularly hard to work with or anything. Hobbyist stuff is just as likely as commercial stuff to end up in a landfill leaching into groundwater, so use lead free. Agreed. One of my colleagues always says "if you can't solder with lead free, you can't solder". It's really not that bad compared to leaded.
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Sep 29, 2018 08:05
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Splode posted:Agreed. One of my colleagues always says "if you can't solder with lead free, you can't solder". It's really not that bad compared to leaded. Easier to fry parts trying to hit lead free reflow temps with a DIY toaster oven or hot plate than a commercial oven.
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Sep 29, 2018 16:21
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If there's an easier, more durable and tolerant option, I'm gonna take it.
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Sep 29, 2018 16:49
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Queen Combat posted:If there's an easier, more durable and tolerant option, I'm gonna take it. Please, Think of the Children
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Sep 30, 2018 10:36
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I mean I think if all the lead waste generated by all the hobbyists in the world were to suddenly disappear it wouldn't even make a detectable dip compared to the background lead levels in landfills but I get your point.
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Sep 30, 2018 14:55
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lets go back to all through hole except this time everything is press fits and crimps
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Sep 30, 2018 22:58
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i have a weird amalgamation of electronics experience and Im ready to get into it now. i have a BA in computer science. its related to my current job and i like programming. when i was in college i studied abroad in australia and did lot of art/tech classes, one which was about electronic art. i learned to solder and hack items there. when i graduated college i moved to a random place and got a job as an electronics tech and learned to solder pretty well and worked on small boards a lot. (cell phones). i really want to get into electronics, and i recently moved places and am getting a solder station for myself during october. im looking for advice on how to get into electrical engineering/robotics. between high school and college i only ever took 1 physics class and electricity was like a week of info, so i know bare min about circuits. i have an arduino i can play with, and im willing to scourge used stores for cheap electronics i can manipulate. Ideally in about two years id like to get a degree in robotics, but i feel like i can start my passions now and maybe at least have a portfolio for entering school later. what should i read? what should i practice programming in (language?) ive seen python and C used a lot, i know C well but prefer programming in ruby. is everything you make functional? ive thought about playing with dumb stuff like making sex toys talk, but thats pretty shallow of an idea.
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Oct 2, 2018 00:20
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Why is that a shallow idea? You pretty much need a project, and that seems like a good start. Choose an Arduino variant that fits in your available space, and start googling how to hook it up to some sort of sound module or Alexa or whatever. I like the NodeMCU, because it's small, beefy, cheap, and has WiFi. Later you can also get a motor shield for it and Google how to hook that up, too
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Oct 2, 2018 00:54
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