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I like automotive inline fuses. Cheap and easily available. Doing waterproofing properly is pretty tricky, so I guess try all sorts of different things. Heat shrink is flimsy and gets small holes really easily, I'd probably use a silicone tube instead.
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Dec 28, 2015 18:48
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ante posted:I like automotive inline fuses. Cheap and easily available. ante posted:Doing waterproofing properly is pretty tricky, so I guess try all sorts of different things. Heat shrink is flimsy and gets small holes really easily, I'd probably use a silicone tube instead. EDIT: Hotglue. I meant hotglue. Skyscraper fucked around with this message at 19:46 on Dec 28, 2015 |
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Dec 28, 2015 18:55
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SandBox posted:looking on http://www.marsport.org.uk/smd/mainframe.htm Yeah "81B" is probably the correct interpretation as all other permutations don't seem to correspond to any real parts. But this one is also in the SOT23 packaging while the one on the board appears to be DO-219AB, so, yeah, what the hell.
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Dec 28, 2015 19:45
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Skyscraper posted:I really like the design of this kind of thing if that's what you mean. I see the fuses are 1-20 amps, but I don't know a lot about electrical fires, what's a good fuse to use that will always stop fires, but is unlikely to overload in most applications? Whether something starts a fire depends entirely on the wire/trace gauge of the circuit. The fuse should be sized to open below the safe carrying capacity of the circuit. Google for th capacity of wires or traces.
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Dec 28, 2015 20:19
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asdf32 posted:Whether something starts a fire depends entirely on the wire/trace gauge of the circuit. The fuse should be sized to open below the safe carrying capacity of the circuit. Google for th capacity of wires or traces.
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Dec 28, 2015 20:40
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Skyscraper posted:Oh, yes, I understood that. Unless I'm extra confused, when shorts occur, current draw can increase significantly, which is often responsible for overloading the carrying capacity of a circuit. I'm trying to find a good rule of thumb fuse to use that will blow when the current has increased past what would be sensible for most applications not involving moving parts. I know the correct answer will be "use a fuse with a carrying capacity similar to the expected draw of the circuit" but I'm looking for a rule of thumb that is good enough to use for safety for testing and prototyping. Rules of thumb: 80% of the capacity of your wire. If your wire can sustain 10A, get an 8A fuse. Alternatively, 120% of all non-motor loads + 150% of all motor loads. The fuse will pop if something goes drastically wrong in the circuit, but not under normal conditions. babyeatingpsychopath fucked around with this message at 01:07 on Dec 29, 2015 |
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Dec 29, 2015 01:03
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Skyscraper posted:Oh, yes, I understood that. Unless I'm extra confused, when shorts occur, current draw can increase significantly, which is often responsible for overloading the carrying capacity of a circuit. I'm trying to find a good rule of thumb fuse to use that will blow when the current has increased past what would be sensible for most applications not involving moving parts. I know the correct answer will be "use a fuse with a carrying capacity similar to the expected draw of the circuit" but I'm looking for a rule of thumb that is good enough to use for safety for testing and prototyping. It's obviously application specific so there is no great answer. 1A or 3A or 5A covers many general processing/control applications in 3.3V-12V. Though note that modern regulators and DC-DC converters as well as most outputs on modern IC's are self limiting and tolerant of shorts. In this case your fuse may never blow and therefore isn't adding a ton of value. It's worth having overcurrent protection in a system to prevent cascading failures (I.E. prevent a short on board B from bringing down board A), but in that case you need fairly accurate current limits (less than board A supply but more than board B's draw). I'd also take a look at "resettable fuses" (PTC's). For low voltage applications they are decent, though not as ideal as you ever want them to be (look at littelfuse).
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Dec 29, 2015 02:50
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babyeatingpsychopath posted:Rules of thumb: asdf32 posted:It's obviously application specific so there is no great answer. 1A or 3A or 5A covers many general processing/control applications in 3.3V-12V. Also, you're right, Littelfuse fills all kinds of fuse-related needs.
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Dec 29, 2015 18:04
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Is there a whole lot of difference between the ignition coil on a car and an induction coil? A project I am working on requires a working spark plug.
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Dec 29, 2015 21:52
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DreadLlama posted:Is there a whole lot of difference between the ignition coil on a car and an induction coil? A project I am working on requires a working spark plug. As far as I know an ignition coil is a type of induction coil. Although I'm also pretty sure they call the coils in induction furnaces the same thing when they're obviously not so maybe I don't know what I'm talking about at all. As far as getting it to work I know I don't know what I'm talking about and would probably just try and scoop the whole system out of like some small engine or scrapyard or something. I went and looked up both on Wikipedia and they know more than I do so this is basically a worthless post I guess.
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Dec 29, 2015 23:46
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DreadLlama posted:Is there a whole lot of difference between the ignition coil on a car and an induction coil? A project I am working on requires a working spark plug. Do you actually need an automotive spark plug, or just a spark ignition source?
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Dec 30, 2015 01:17
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Just an ignition source. edit: SniperWoreConverse posted:As far as getting it to work I know I don't know what I'm talking about and would probably just try and scoop the whole system out of like some small engine or scrapyard or something. This is something I'm considering but a complete automotive system requires a working alternator and a feedback control circuit which varies the strength of the electromagnet according to the needs of the battery. I have no idea how said control circuit works. Although it is my intention to do as you say and pull something out of a scrapyard, I need to shrink my shopping list. Right now it just says, "get car stuff for the sparker" and I need to narrow it down or this is going to get expensive. DreadLlama fucked around with this message at 01:53 on Dec 30, 2015 |
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Dec 30, 2015 01:38
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DreadLlama posted:Just an ignition source. BBQ piezo
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Dec 30, 2015 02:04
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That's Plan B. edit: The project is experimental. It is probable that I will be fiddling with needle valves when trying for ignition. I don't want to have to be hammering on a piezoelectric igniter as well. DreadLlama fucked around with this message at 02:13 on Dec 30, 2015 |
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Dec 30, 2015 02:09
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Gas cooktop igniter?
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Dec 30, 2015 02:32
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Take it into a more lawnmower direction? Probably also don't want to be pulling ripcords while messing with valves, but idk, you could maybe rig up something like an old singer-style foot pedal. Sounds retarded, right? But the magneto in a lawnmower shouldn't give a gently caress if you had batteries or circuits or nothing. It'd probably be a huge pain in the rear end to manually turn it or w/e, but if you had just an external motor where you could dial the speed that could maybe work? Making your own engine reminds me of those old silent movie dudes who had to go out and physically crank the propeller to get the engine started on their bullshit gyroaerodyne that would never work. Wait, if you're considering using piezo how would you even get it to run past like half a stroke? Are you talking about some kind of next-level-DIY crazy rear end turbine or something? If you're building a tank or jet please livestream killdozer2.0 in GBS instead of making us look at the news.
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Dec 30, 2015 02:47
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DreadLlama posted:Just an ignition source drat, I was gonna suggest this, but they no longer sell it: https://www.sparkfun.com/products/retired/11218 with something like that, you only need to make a simple spark gap (with a couple of steel nails, for example), since you probably don't need it to last for millions and millions of cycles. EDIT: Look for a gas grill "spark generator" powered by a AA battery. There seem to be a lot of choices for those, and it's probably exactly what you want. You could even get a gas grill spark gap too, probably. EDIT #2: a hot surface ignitor would probably work for certain applications too, as long as you have a power supply or battery that can supply enough power. https://www.sparkfun.com/products/11694 Slanderer fucked around with this message at 03:16 on Dec 30, 2015 |
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Dec 30, 2015 03:08
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Slanderer posted:drat, I was gonna suggest this, but they no longer sell it: quoting myself because too many edits: this might be everything you need for electronic ignition- you just need to supply a grounded steel chassis that you are making the spark against, i think: http://www.amazon.com/Weber-Battery-Electronic-Collector-67847/dp/B007I77BHI/ EDIT: to be clear this ISNT a piezo ignitor Slanderer fucked around with this message at 03:25 on Dec 30, 2015 |
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Dec 30, 2015 03:19
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Slanderer posted:drat, I was gonna suggest this, but they no longer sell it: http://www.banggood.com/DC-3_6V-6V-To-400KV-Boost-Step-Up-Power-Module-High-Voltage-Generator-p-915426.html
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Dec 30, 2015 03:23
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SniperWoreConverse posted:Wait, if you're considering using piezo how would you even get it to run past like half a stroke? Are you talking about some kind of next-level-DIY crazy rear end turbine or something? If you're building a tank or jet please livestream killdozer2.0 in GBS instead of making us look at the news. How did you know? There's a lot of youtube needed to back this up so I'll start with a summary. I plan to pyrolyze a quick growing nuisance shrub (Zanthoxylum americanum) and turn its products into electricity and tractor fuel. Wood contains long hydrocarbon chains. If you break the chains apart you can use the products in the same way as you use fossil fuels. On Pyrolysis: Animated/theory: https://www.youtube.com/watch?v=kI7s6IRpOHA Built/practical: https://www.youtube.com/watch?v=Zzv6fIDsNwM Important note: While some people will tell you that you strictly need Type-Y Faujasite or everything will explode and be terrible, you can actually just use crushed flower pots as a catalyst. https://www.youtube.com/watch?v=ZYyKUePdC2Y I've already located most of the parts I need to build the gasifier. But I can't get at them until Summer. In the meantime I'm researching the turbocharger. I need to get one turbocharger spinning off woodgas, as per the following video: https://www.youtube.com/watch?v=E-8BX7dUk5c And then I'll need the intake half from a second turbocharger eating the exhaust gas from the first, with an alternator attached to it instead of the exhaust half of the turbo as is traditional. math (I'm very grateful to colinfurze for supplying the following ratios so that I don't have to find them myself:) code:In the meantime I have to figure out how to ignite the turbo. I'm inclined to use car parts. I'll be using an alternator and car battery at minimum, so it makes sense to me to use junkyard parts as they're likely to be compatible. However, that said: ante posted:http://www.banggood.com/DC-3_6V-6V-To-400KV-Boost-Step-Up-Power-Module-High-Voltage-Generator-p-915426.html Does that thing work? It's in my price range.
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Dec 30, 2015 03:46
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I think someone was playing with one in this very thread and killed it pretty quickly, just like that SparkFun guy. I also have one that I haven't plugged in yet. Should be lots of youtube videos on them, too. But yeah, it creates a reliable arc. I guess you if go easy on it, you probably won't burn it out.
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Dec 30, 2015 04:46
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Yeah the last time those high voltage supplies were posted in this thread a bunch of us bought some (off ebay, for like $3). I still have mine and it still works, but I doubt it's robust enough to work as any sort of igniter. I mostly just use it for making cool sparks and throwing off corona discharge, and even then I use it really infrequently 
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Dec 30, 2015 05:15
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I have a friend with an old, old 3-phase welder from the 60's, he loves the heavy old lug and think it works better than any modern inverter. However now it went and blew up and he's having a hard time finding a spare. It's this diode that's the hangup: http://americanmicrosemi.com/information/spec/?ss_pn=S3AN125 I've asked these guys above for a quote with shipping to Finland, but it struck me that it could be useful if one could find an equivalent diode of another make that is more common. This is the only site on the internet I've found that sells this. But I don't know enough about electronics to know where to find an analogue to this part. or even if one exists. Any electronics experts here?
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Dec 30, 2015 05:53
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DreadLlama posted:Is there a whole lot of difference between the ignition coil on a car and an induction coil? A project I am working on requires a working spark plug. Yes. It is, though there are several other things that an induction coil refer to, that are completely different, like for an induction forge, induction stoves, and inductive chargers. That said, a car ignition coil is a transformer. It has a low impedance primary that you drive at some lowish voltage, and highish current and it's secondary puts out a high voltage at less current. They're actually quite easy to drive if all you need is sparks. All you need is a power transistor, I'm going to pick a TIP147, on the grounds that I've seen it successfully used, and some pwm source. A 555, 2 transistor oscillator, an opamp, or a uC would all be fine. You'd also want a diode to protect the power transistor. Pretty much any diode here would be fine. And that's it. To start and stop your sparks you'd just start and stop your PWM signal. If you only wanted one spark, in theory you'd just need one rising or falling edge to go though the primary. Though if you're trying to light something, there's no reason to have just one spark. https://www.youtube.com/watch?v=QkcsKOdzkQI
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Dec 30, 2015 05:57
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His Divine Shadow posted:I have a friend with an old, old 3-phase welder from the 60's, he loves the heavy old lug and think it works better than any modern inverter. However now it went and blew up and he's having a hard time finding a spare. It's this diode that's the hangup: From your link and post: code:Important qualities are: Output current: 150A or higher Reverse voltage: 240V or higher And, uh, that should be it. Drilling down the categories on Digikey, sorted by price: http://www.digikey.com/product-detail/en/IDW100E60/IDW100E60-ND/2337940 http://www.digikey.com/product-detail/en/VS-150EBU04/150EBU04-ND/446538 http://www.digikey.com/product-detail/en/150KR60A/1242-1202-ND/3927567 Totally different form factor on all of them, and a pretty big difference in price, but the $2 one should actually be fine.
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Dec 30, 2015 07:12
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ante posted:From your link and post: It had a peak surge current of 3.3kA which seems like it might be important in a welder, that was the spec that I was having trouble meeting when I was looking around. I found a few but you could only order them in batches of 10 and they were $50 each
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Dec 30, 2015 07:18
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Parallel Paraplegic posted:It had a peak surge current of 3.3kA which seems like it might be important in a welder, that was the spec that I was having trouble meeting when I was looking around. I found a few but you could only order them in batches of 10 and they were $50 each Good call. The third link I posted is good for 3.7kA half sinewave, so we're still good! And ten of the $2 ones in parallel would work, too 
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Dec 30, 2015 07:29
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I will shortly have (another) very old camera meter that requires 1.35Vs to operate accurately and is intended to be used with 625 size cells. Now you can get 1.35V zinc-air batteries in this size but it's a pain in the butt since it's not like local places will have it. But I have heard of people making some sort of adapter to drop the voltage of more common 1.5V button cells down to 1.35V. How the gently caress do I pull that off? I was thinking of a diode that would have a voltage drop of .15V, but gently caress if I can find one. ed: quick update, looks like the silver oxide batteries (which are preferred over alkaline for these meter adapters) put out 1.55V, so I need to drop it by .2V. Parts Kit fucked around with this message at 09:13 on Dec 30, 2015 |
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Dec 30, 2015 09:09
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ante posted:Good call. The third link I posted is good for 3.7kA half sinewave, so we're still good! Is it important that the rectified current is specified as DC? I saw there was 150A and 150A(DC) to choose from when applying filters, and this welder wants to output power in the form of DC .
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Dec 30, 2015 09:11
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His Divine Shadow posted:Is it important that the rectified current is specified as DC? I saw there was 150A and 150A(DC) to choose from when applying filters, and this welder wants to output power in the form of DC . Nope, shouldn't matter. Parts Kit posted:I will shortly have (another) very old camera meter that requires 1.35Vs to operate accurately and is intended to be used with 625 size cells. Now you can get 1.35V zinc-air batteries in this size but it's a pain in the butt since it's not like local places will have it. But I have heard of people making some sort of adapter to drop the voltage of more common 1.5V button cells down to 1.35V. How the gently caress do I pull that off? I was thinking of a diode that would have a voltage drop of .15V, but gently caress if I can find one. A diode should work. It's not the best solution because it won't be super consistent at different currents, but I guess with battery-tolerant systems, it should be okay. http://www.digikey.com/product-search/en/discrete-semiconductor-products/diodes-rectifiers-single/1376383 Lots of options with 200mV forward drop there. Better would be to use a LDO regulator: http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-voltage-regulators-linear/2556290
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Dec 30, 2015 12:54
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Holy smokes got a quote for the diodes, 75 dollar a piece and a whopping 126 dollars in shipping. I think it's better to sell the welder for scrap, he got it for free after all.
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Dec 30, 2015 16:49
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His Divine Shadow posted:Holy smokes got a quote for the diodes, 75 dollar a piece and a whopping 126 dollars in shipping. I think it's better to sell the welder for scrap, he got it for free after all. Wire up a buttload of parallel 3A generic diodes. I have about 700x 1N5407 diodes, you want some?
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Dec 30, 2015 20:27
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There's still this option, much cheaper which is being investigated now: http://www.digikey.com/product-detail/en/150KR60A/1242-1202-ND/3927567
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Dec 30, 2015 20:32
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Are there any bench tools or multimeters you guys would recommend with nice connectivity options? I want something that can be connected to a computer or a smartphone with software for easy datalogging, using the full graphics display, graphing samples over time, etc. I know a lot of multimeters have serial out, but jfc what is this, the 80s? Are there things with more modern options such as bluetooth, wifi, USB? Doesn't need to even have its own display. I guess I'm looking for this sort of thing basically http://www.ni.com/virtualbench/buy/ Except my price range would be more like 1/10th that thing.
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Dec 30, 2015 21:33
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peepsalot posted:Are there any bench tools or multimeters you guys would recommend with nice connectivity options? I want something that can be connected to a computer or a smartphone with software for easy datalogging, using the full graphics display, graphing samples over time, etc. It's not a multimeter, but for a connected logic analyzer, I'm a big fan of Saleae Logic. Get the beta version of the software -- it's got lots more features and is pretty stable.
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Dec 30, 2015 21:42
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KnifeWrench posted:It's not a multimeter, but for a connected logic analyzer, I'm a big fan of Saleae Logic. Get the beta version of the software -- it's got lots more features and is pretty stable. Actually I tried a logic pro at work a while ago and all it did was crash. I submitted 4 or 5 bug reports, all different modes of crashing, and sent it back. Its a piece of poo poo.
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Dec 30, 2015 22:49
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peepsalot posted:Actually I tried a logic pro at work a while ago and all it did was crash. I submitted 4 or 5 bug reports, all different modes of crashing, and sent it back. Its a piece of poo poo. I've got a logic (the older one) and it has been rock solid and a great tool. Zero problems with it.
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Dec 30, 2015 23:24
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peepsalot posted:Actually I tried a logic pro at work a while ago and all it did was crash. I submitted 4 or 5 bug reports, all different modes of crashing, and sent it back. Its a piece of poo poo. Weird. I've been using a logic pro at work for months. The only crashes I've had were when the computer goes to sleep while it's connected (on a Mac). Sorry to hear your experience sucked.
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Dec 30, 2015 23:27
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ante posted:A diode should work. It's not the best solution because it won't be super consistent at different currents, but I guess with battery-tolerant systems, it should be okay.
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Dec 31, 2015 01:44
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peepsalot posted:Wire up a buttload of parallel 3A generic diodes. I have about 700x 1N5407 diodes, you want some? Diodes don't parallel well. They have a negative relationship between temp and voltage drop which creates a hogging effect with runaway temperature and destruction.
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Dec 31, 2015 01:58
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