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Bad Munki posted:I realize the normal need for a resistor, but that significantly complicates the circuit in this case. The point is to not have anything more than is absolutely necessary. I guess maybe I could solder one in right against the LED and then use the resistor's remaining lead to contact the battery... Normally both of those things would be a risk with a bigger battery, but a tiny button cell like that has tens of ohms of internal resistance that let you get away without the resistor.
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Sep 23, 2011 00:55
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You are likely overdriving the LED, which means it will overheat and die. Not sure what the internal resistance of one of those batteries is, but you could easily check how much current the LED is drawing with a run of the mill multimeter.
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Sep 23, 2011 00:56
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Yeah, you certainly won't cause a fire or anything, but I'd bet that LED's lifespan will be pretty short. Totally worth testing, though.
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Sep 23, 2011 02:05
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In my random testing today (read: connecting one and leaving it sitting while I was playing with other stuff, and then making another and noticing any differences and swapping components to see what's what) it actually seems to be harder on the battery than the LED.
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Sep 23, 2011 02:08
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Bad Munki posted:In my random testing today (read: connecting one and leaving it sitting while I was playing with other stuff, and then making another and noticing any differences and swapping components to see what's what) it actually seems to be harder on the battery than the LED. yup. Lets say due to internal resistance, you're passing 20mA. The battery dissipates (1.3V*20)mW, and the LED uses (1.7*20)mW. Hwwever, LEDs convert energy to light at 50-90% efficiency, so it ends up producing less heat that the battery. 
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Sep 23, 2011 02:30
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Yeah, that's what I imagined, although neither even became warm to the touch. Oh, and I don't know if it was in the original picture or even matters, really, but it's a 3v battery.
Bad Munki fucked around with this message at 02:34 on Sep 23, 2011 |
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Sep 23, 2011 02:31
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Electronics: am I doing this right now, guys? Guys?? Seems to still be bright enough for my needs, so I guess I can work a 100Ω resistor into each one. That puts it down to, like, 6mA instead of the 30 it was at before. I've got some 200Ω ones I could use too. Bad Munki fucked around with this message at 03:31 on Sep 23, 2011 |
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Sep 23, 2011 03:28
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I want to know what that is for.
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Sep 23, 2011 05:38
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insta posted:I want to know what that is for. http://www.instructables.com/id/LED-Throwies/ Never seen these before?
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Sep 23, 2011 05:40
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Actually, no, that's not it, but...okay, I am a giant nerd. Maybe not physically giant, but I make up for it as follows: It's a bit of scenery for some tabletop gaming. The standing stone is made of pink foam core I had laying around. The LEDs were also in my stash, as are any resistors I opt to add. The picture doesn't really do it justice: in person, it looks pretty drat sick, as it lights up a lot better than the picture makes it appear. Roughly 1.25" tall, so as you can see, space is an issue. This weekend, I'll paint it to actually look like stone (that's just primer on there now.) (Ginger cleric was painted by a friend. Said cleric is played by an actual ginger.)
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Sep 23, 2011 05:49
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Here is maybe a better picture of the thing itself. Even this picture doesn't really nail it. You just cannot paint a glowing thing. With this, the darker the room gets, the more vibrant the rune becomes. Your eye can pick that up even in a fairly light room. You look at it, and you brain just goes, "Whoa!" It's neat, and the investment is pretty much nil. What I really want is to find 3v batteries in the 1.55v form factor. The 1.55v hearing-aid batteries are generally half the diameter but twice the thickness. Which, of course, would work perfectly in my case, since they would take up a volume much closer to that of the LED itself. I suspect I may be able to order such a thing online, but I haven't looked yet.
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Sep 23, 2011 06:05
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Huuuuge nerd. You could stack the 1.55v batteries in series to get the same-ish voltage in a different form factor
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Sep 23, 2011 06:18
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Ooh, that's true, not sure why I didn't think of that. That may be nice to keep in mind, even if it would increase the cost-per-monolith, although I bet I could find a cheap source for batteries in China or some such.
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Sep 23, 2011 06:23
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Double check this on Google first, but my buddy just told me a couple weeks ago that Energizer (or maybe it was Duracell) just uses those batteries stacked on top of each other to make AAs. So cutting open a AA is pretty much the cheapest way to get them. Edit: not AAs, these ones: http://www.youtube.com/watch?v=QxS38_u7Mnw ante fucked around with this message at 06:28 on Sep 23, 2011 |
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Sep 23, 2011 06:25
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ante posted:Double check this on Google first, but my buddy just told me a couple weeks ago that Energizer (or maybe it was Duracell) just uses those batteries stacked on top of each other to make AAs. So cutting open a AA is pretty much the cheapest way to get them. http://www.youtube.com/watch?v=s_8n2Qgguto
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Sep 23, 2011 06:29
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1,500 AAs? gently caress YES sign this goon up. I'm sure my roommate won't mind if I borrow his battery.
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Sep 23, 2011 08:15
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Bad Munki posted:I realize the normal need for a resistor, but that significantly complicates the circuit in this case. The point is to not have anything more than is absolutely necessary. I guess maybe I could solder one in right against the LED and then use the resistor's remaining lead to contact the battery... Decreased LED and battery life are the only real downsides. Instead of 10 years, your LED will last 10 days, and instead of 10 days of battery life, you'll get 1 day. As an aside, it is *really* fun to toss one of these LED throwies in a helium balloon and watch where they go. It's incredible how far off you're able to see them at night.
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Sep 23, 2011 12:21
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Bad Munki posted:Seems to still be bright enough for my needs, so I guess I can work a 100Ω resistor into each one. That puts it down to, like, 6mA instead of the 30 it was at before. I've got some 200Ω ones I could use too.
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Sep 23, 2011 13:18
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Bad Munki posted:http://www.youtube.com/watch?v=s_8n2Qgguto This reminds me of those Household Hacker videos some goon made a few years back. Best viewed knowing that at the time a lot of people thought these were legit. http://www.youtube.com/watch?v=tvGVir25EJc http://www.youtube.com/watch?v=GfPJeDssBOM http://www.youtube.com/watch?v=8m8fbnShPcw http://www.youtube.com/watch?v=0rA-zhTJuFU
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Sep 23, 2011 13:20
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ANIME AKBAR posted:If you look hard enough you can find LEDs with internal resistors built in. But I think they're usually meant to run off 5V. I imagine I could find such a thing on digikey; what sort of search parameters would I use to narrow it down?
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Sep 23, 2011 13:21
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Digikey apparently does carry some, but it's not a searchable parameter. I was able to find at least some by searching "5V led." Maybe you could look for "3V led" or "3.3V led." I sort of doubt you'll find anything specifically at lower voltages though. I would look for 5V LEDs that are rated for higher currents than you want and use them at 3V and hope they still light up.
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Sep 23, 2011 13:39
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I've been thinking and reading about power supplies and transformers and such a lot lately, and had a particular idea I was wondering if people could comment on. My idea is a sort of binary/digital variable voltage transformer. This can be viewed as an alternative to the variac that would not involve any wiper or moving parts. It's physically set up just like a normal transformer, with a primary coil, and multiple secondary coils, say for example 8 of them. Each secondary coil would a number of turns based on a power of 2. So 1,2,4,8,16,32,64 and 128 turns in each coil, or any multiple of those numbers. Then you can connect various coils in series and get whatever output voltage you want(with 8 bit resolution for 8 total coils, so ~0.5V steps for 0-120V for example). The connections between coils could maybe be done with solid state relays maybe for automation(as opposed to manually rewiring the coil terminals when you want to change voltage). Also the coils could be in different gauge wire, so that the coils with lower # turns could handle higher higher current at lower voltage, keeping overall power output capability roughly constant. Has this sort of thing been done before? Is there a reason this is a bad idea? Would solid state relays cause a lot of loss? Is there some other more suitable component for connecting the coils in series? Also I supposed you could do the same sort of thing on the primary coil for an even wider range of voltages, but maybe I figured I'd take things one step at a time. peepsalot fucked around with this message at 08:17 on Sep 24, 2011 |
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Sep 24, 2011 08:03
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Does anyone have experience with long strips of addressable LEDs? Basically this guy but hopefully I'll be able to find one for slightly cheaper. It's for a class project, and we're taking an audio source, dividing up the frequencies, and trying to get them to correspond to 'pulses' of certain LED colors. Problem is, this is the only strip that we've been able to find (and trust the manufacturer!). Any other suggestions? We've looked into EL Wire, but it doesn't support variable brightness, just on/off states, so it wouldn't be ideal.
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Sep 24, 2011 09:15
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DahtBard posted:Does anyone have experience with long strips of addressable LEDs? Basically this guy but hopefully I'll be able to find one for slightly cheaper. It's for a class project, and we're taking an audio source, dividing up the frequencies, and trying to get them to correspond to 'pulses' of certain LED colors. Problem is, this is the only strip that we've been able to find (and trust the manufacturer!). Any other suggestions? We've looked into EL Wire, but it doesn't support variable brightness, just on/off states, so it wouldn't be ideal. Honestly, $35 seems like a pretty good price. How cheap do you need it to be?
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Sep 24, 2011 15:17
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peepsalot posted:I've been thinking and reading about power supplies and transformers and such a lot lately, and had a particular idea I was wondering if people could comment on. If you're talking about transformers on the very high power side of things, then yes they will have transformers with secondary taps, though I'm not sure if they use continuous tapping (like in a variac) or manual tapping or solid state or whatever. I'd recommend checking out this thread for that kind of stuff. ANIME AKBAR fucked around with this message at 16:07 on Sep 24, 2011 |
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Sep 24, 2011 15:54
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ANIME AKBAR posted:This is a nice idea, but overall people have learned to deal with a wide range of available AC voltages on the load side of things. Many offline power supplies are specified to run off anywhere between 95-135VAC, or even 95-265VAC (with the addition of a little manual switch). So there's no real need to have your AC voltage perfectly calibrated in the vast majority of applications.
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Sep 24, 2011 22:27
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peepsalot posted:I'm talking about this for a sort of general purpose, versatile bench power supply for hobbyist, experimenting etc. quote:You could use it on big electromagnets, electrolysis, variable speed large motor, heating coils, whatever.
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Sep 25, 2011 05:17
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ANIME AKBAR posted:A lot of older linear benchtop supplies use line transformers with multiple secondary taps, which are usually selected with relays. Yeah the problem with that though is I've already got one of those.   I guess those were bad examples, and definitely didn't mean to limit the applications to just that. It would ideally be usable for all sorts of other applications including those that require specific voltages. Basically the idea would be "Think of anything that requires electrical power to operate." And to be able to say for the vast majority of those things, this power supply would be able to handle it. I guess this is the main power supply concept that's been bugging me. I feel like with today's technology everyone should be able to have their own low cost, high power, variable voltage, quality power supplies that could be used for drat near any application the feel like. Maybe(probably) the binary transformer implementation is not ideal for this sort of thing, but it was just one idea I had that I thought could be interesting. Maybe a switching mode power supply would be better. Maybe some other power supply technology that I'm ignorant of. The overall idea I have in mind is something with a programmable microcontroller at the heart, running open source code and all open hardware. With the actual circuit design being as simple and low cost/generic as possible, while offloading as much complexity as possible to the software side of things. It could be designed with minimal physical interface to keep cost/complexity down, basically a box with input terminals, output terminals, and serial port. No LCD display/knobs/etc, all control and monitoring done over serial. Some nice desktop applications that could interactively control the supply via serial could be developed. It wouldn't necessarily have to be hooked up via serial port all the time either. You could say load the "lead acid charging" program on to it and just let that program do its thing after disconnecting serial. I really want to make something like this but I fear my electronics design expertise will never be good enough to design myself. I am a software developer by trade with some experience with embedded development so digital circuits with logic gates and all that jazz makes sense to me, but the analog power stuff always throws me for a loop. I've been reading up a bit on SMPS design, trying to learn as much as possible. I was searching if there was an existing simlar project to this, and found these guys whom seem to be wanting a pretty similar thing to me. http://opensourceecology.org/wiki/Universal_Power_Supply/Research_Development It doesn't look like they've gotten anywhere as far as prototyping anything though. peepsalot fucked around with this message at 06:51 on Sep 25, 2011 |
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Sep 25, 2011 06:39
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taqueso posted:Honestly, $35 seems like a pretty good price. How cheap do you need it to be? Just as cheap as possible to be honest. We really have no problem with the price, as we feel things such as waterproofing really do make it a good deal. Mostly just asking a point of curiosity, as such a cool item seems like it what have more suppliers. No big loss!
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Sep 26, 2011 07:55
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peepsalot posted:I was searching if there was an existing simlar project to this, and found these guys whom seem to be wanting a pretty similar thing to me. There's a reason power supplies have pretty specialized functions. It's just cheaper and easier to work with them. I can't really think of any situation where you would be so uncertain about your power source and your load's needs that you couldn't throw together a couple inverters or rectifiers to get the job done.
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Sep 26, 2011 13:49
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Hey all, I'm working in a student radio station, and I'm kinda the go-to-guy for engineering. Since we're webcast, I mostly have to deal with software and basic audio engineering issues. I'm not much of a a really-in-depth electronics person. I've been put to the task of trying to get our on-air signal lights to work again, and I think I might have found a clue.  I know this is some kind of relay, but I'm not really sure what it may need to function. The +3 and -4 (Inputs) are connected to some speaker wire that is cut off - this makes me suspect it might be the connection I need. The other two leads are connected into some heavy duty building wire. It's pretty common for stuff to have been put into disuse and randomly abandoned. I wouldn't be surprised if this is what I'm looking for, but if I could get some ideas as to what this thing requires to trigger, I'd be more sure.
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Sep 27, 2011 22:23
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WrongWay Feldman posted:I know this is some kind of relay That is an SSR or Solid State Relay. In order to switch it on you need to apply a small amount of dc voltage. The label says 3-32 VDC so you should be able to apply that to it to get it to energise the output.
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Sep 28, 2011 00:45
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Looking at it awhile longer, I kinda realized that, now I feel dumb for asking. What about the level of Amps? Is there a level I need to worry about it being damaging, or in most cases, or do I fret too much?
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Sep 28, 2011 00:49
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The only thing that could be damaged is on the coil side assuming you aren't trying to switch 120VAC into something you shouldn't. SSRs probably shouldn't have low coil resistance, inductive kickback, or anything else scary.
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Sep 28, 2011 00:58
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Another quick question: Recommendations on a place to buy servos? We've looked around at various hobby stores, but we're not quite sure yet. The use of it is kind of interesting. I'm on my school's Baja SAE team (race dune buggies), and for the first time we have someone who is wheelchair-handicapped. We want to make sure everyone can drive (always a yearly goal), so obviously a physical pedals won't do it. We think the basic solution is going to be rigging up some racing bike-esque brakes handles to use as throttle/brake. They'll control a pot of some kind which some small chip will send as a reading to a servo that'll actually move the throttle switch. It really doesn't need that much power, but the thing needs to be able to handle a Baja race. We'll secure it down as best we can, but at the end of the day there will be some jostling. Any suggestions?
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Sep 28, 2011 06:23
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http://www.pololu.com/ is a popular choice, I don't have any experience with them, though. Fun fact: I just bought 300 ICs from http://components.arrow.com/products/ for like, $60 including shipping. And the package got here (Canada) in 48 hours over a weekend. Two days before my credit card transaction cleared.
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Sep 28, 2011 07:01
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Pololu and Solarbotics are great. Solarbotics can take a while to ship, though. They're located in Canada, and a lot of people I've known have packages held up in customs.
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Sep 28, 2011 13:08
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ante posted:http://www.pololu.com/ is a popular choice, I don't have any experience with them, though. Did they pack each IC in a three foot tube, with all of the tubes in a triangular cardboard box? Because that's how arrow always ships stuff to me, and it's loving annoying.
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Sep 29, 2011 05:05
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ANIME AKBAR posted:Did they pack each IC in a three foot tube, with all of the tubes in a triangular cardboard box? Because that's how arrow always ships stuff to me, and it's loving annoying.  RS shipped me this pile of 250 individually wrapped transistors (P2N2222As) once.
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Sep 29, 2011 15:41
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longview posted:
 Why would anyone do that?
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Sep 29, 2011 17:38
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