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armorer posted:Whichever switch that is, I didn't see it All DPST/DPDT switches I've ever seen work like that, where'd you see one that didn't?
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Oct 3, 2019 17:40
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Shame Boy posted:All DPST/DPDT switches I've ever seen work like that, where'd you see one that didn't? It wouldn't be double pole in any meaningful sense if it were electrically interconnected, it would be like a redundant SP
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Oct 3, 2019 17:55
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Shame Boy, did you ever end up getting Knoll's Radiation Detection and Measurement? Did you build anything cool? I remembered suggesting that book to you since I pulled it out while designing some preamplifier poo poo for my boss last week. Kind of curious if you did anything with it.
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Oct 3, 2019 17:57
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Shame Boy posted:All DPST/DPDT switches I've ever seen work like that, where'd you see one that didn't? I'm phone posting, but all the diagrams I saw in the datasheets I looked at (like, 5 or 6?) Showed either a single bridge or else connected grounds. I was expecting them to work like you're all saying though, so I was a bit confused by what I was seeing.
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Oct 3, 2019 19:54
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BattleMaster posted:Shame Boy, did you ever end up getting Knoll's Radiation Detection and Measurement? Did you build anything cool? Oh yeah I did, thanks! I haven't really gotten around to diving into it real deep yet but I've read bits and pieces and looked a few things up and I'm liking it so far. Most recently I was working on that proportional counter design I mentioned and the book + that circuit you posted a while ago for the preamp came in real helpful. I kinda cycle my projects out periodically though so I don't get burnt out / bored with them, as a result I haven't worked on it in a few months and it probably won't be completely finished for a while, but I enjoy the design/build process a lot more than just having the finished product so eh. Right now I'm working on a much quicker and simpler geiger counter design to build with a friend of mine who wants to learn electronics and soldering. She's always wanted some sort of radiation detector "that makes the traditional clicky sound" but also wanted the ability to connect it via USB to her computer for power/ data logging and stuff like that, so we couldn't really just use the ubiquitous MightyOhm kit. Plus I wanted something with each functional block clearly labeled on the schematic to make it easier to understand what's going on. It's really weird going back to all thru-hole parts after spending the last few years doing nothing but SMD, everything seems so goddamn huge now 
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Oct 4, 2019 03:56
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I'd love you to share whatever you have when you finish it. Did you end up getting a gas proportional tube or are you going with a PMT+scintillator or a photodiode detector? Do you have a design for the preamp yet? At my job I was asked to take a look at a preamp that seemed to be broken and when I opened it up I was surprised to see that it uses the same op amp that I picked out for my own design that I never ended up building. So at least I know I was on the right track. Here's the manual for it with the schematic so maybe it will be worth something to you for inspiration if you haven't built one yet. It uses the AD823 which was, when I looked on Digikey, the best JFET input op amp that came in a DIP package. A lot of preamps use discrete JFETs but I thought I could simplify things by using a JFET op amp and I guess you can I never ended up building it though, because I got distracted by work stuff and at work I get to use expensive-rear end Amptek A250 preamp chips, which is what I made the boards for last week. I'm doing an experiment with a new gas mixture so I need to set one up in a current-sensitive configuration instead of a charge-sensitive one to measure absolute gas gain (charge-sensitive is only really good for relative gain) so I had new boards made so I don't have to cannibalize the old ones. I'm pretty excited since I had this gas mix worked out on paper for a long time and I've been pestering my boss to find time to work on it. I'm hoping it works out and we can publish it, since it solves a few problems with a few different dosimetry experiments.
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Oct 4, 2019 10:13
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BattleMaster posted:I'd love you to share whatever you have when you finish it. Did you end up getting a gas proportional tube or are you going with a PMT+scintillator or a photodiode detector? Do you have a design for the preamp yet? Yeah I'll definitely post about it when I finally finish it, and I'm sure I'll have lots more questions about it to ask the thread anyway. I got a cheap new old stock soviet gas tube that I was hoping to get working first, though I also bought a few cheap Hamamatsu PMT's that I saw come up on ebay just 'cuz. When I was designing my high voltage power supply I explicitly built it in such a way that it could be used for either one since its output is nice and quiet and it's very easy to flip the polarity (since I know PMT's tend to use negative voltage, including the few I have). So far the only part I've settled on the design (and built a prototype) of is the power supply though, I've sketched out a few preamp ideas (mostly based on your JFET op-amp design) but not much further than that. Before I rotated off that project I was at the point where I was running LTSpice simulations of a few things, but I was kinda guessing as to what the input signal would look like so probably not the most accurate sim... I also did wind up building a photodiode + scintillator a while ago, but that wasn't really anything of my design, I just put together one of these kits: http://cosmicwatch.lns.mit.edu/detector BattleMaster posted:At my job I was asked to take a look at a preamp that seemed to be broken and when I opened it up I was surprised to see that it uses the same op amp that I picked out for my own design that I never ended up building. So at least I know I was on the right track. Here's the manual for it with the schematic so maybe it will be worth something to you for inspiration if you haven't built one yet. I think I already knew about that specific preamp (or at least another similar model made by that company) because I also got this book a while back which has a design for a preamp very similar to that one, which they explain was adapted from a Spectrum Techniques repair manual. I remember seeing it and going "oh hey wait a sec "BattleMaster posted:I never ended up building it though, because I got distracted by work stuff and at work I get to use expensive-rear end Amptek A250 preamp chips, which is what I made the boards for last week. I'm doing an experiment with a new gas mixture so I need to set one up in a current-sensitive configuration instead of a charge-sensitive one to measure absolute gas gain (charge-sensitive is only really good for relative gain) so I had new boards made so I don't have to cannibalize the old ones. I'm pretty excited since I had this gas mix worked out on paper for a long time and I've been pestering my boss to find time to work on it. I'm hoping it works out and we can publish it, since it solves a few problems with a few different dosimetry experiments. Neat, I'd definitely be interested in reading about it if you get it published. One of the things I was throwing around doing once I got a working system was experimenting with my own gas mixtures, since as far as I know you usually fill them around atmospheric pressure anyway so it wouldn't be too hard to make some kind of container that I can vacuum pump the air out of and refill with argon plus other stuff. Probably would leak out or get contaminated or something pretty fast but I'd think I could at least play with it for an hour or so before it needed refilling.
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Oct 4, 2019 15:14
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my vape box mod isn't working properly after a knock (got tipped over on its side on a hard table); won't heat up b/c it throws a faulty/missing atomizer error no matter what's screwed in (and i did verify that the atomizers im trying work correctly w other vapes). i took it apart and none of the major soldered connections to the terminals have popped loose, and I also used a multimeter to double-check that the path from atomizer wire to battery terminal isn't open at some point (and i dont think i'm accidentally making a connection across half the controller board or sth). can't find any instances of this happening to anyone else that didn't end with "buy another one" or "sometimes they just die", so no luck there. nothing's gotten me anywhere. any other ideas for what else i could screw around with or check before throwing in the towel and buying another one? only thing i can think of is putting a subohm meter together to check that the atomizers are as expected and that there's nothing else... untoward that jumps out at me in the heating circuit, but nothing actually looked like a problem from the (much less accurate) figures my harbor freight-caliber multimeter gave me Ambrose Burnside fucked around with this message at 19:10 on Oct 4, 2019 |
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Oct 4, 2019 19:05
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Ambrose Burnside posted:my vape box mod isn't working properly after a knock (got tipped over on its side on a hard table); won't heat up b/c it throws a faulty/missing atomizer error no matter what's screwed in (and i did verify that the atomizers im trying work correctly w other vapes). i took it apart and none of the major soldered connections to the terminals have popped loose, and I also used a multimeter to double-check that the path from atomizer wire to battery terminal isn't open at some point (and i dont think i'm accidentally making a connection across half the controller board or sth). nothing's gotten me anywhere. Hey I have some immediate experience with this, because I happen to have just been hacking on some old vapes. If I follow you correctly you're saying that the tank works on other vapes, and the vape works with other tanks, just not that pair together? That would be an odd one indeed. My first thought, given that it stopped working after a knock, would be that the coil broke. (One of the old vapes my buddy gave me needs a new coil, and I have some nichrome wire en route to make one for it.) In that case though it wouldn't work elsewhere either. If my following along statement was correct, the only thing I can think is that somehow the 510 connector isn't mating up right for that specific pair but it is mating for others. So maybe clean the contacts really well on both sides and make sure that the spring loaded part isn't stuck or something?
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Oct 4, 2019 19:12
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Sorry, no- it’s the box mod that’s the issue, i meant that i ruled out an atomizer issue by testing them with a vape that does work. I didn’t mention the big one, connectivity, whoops- i’m positive the connections are good, i hooked up the multimeter leads to either side and watched as i assembled it, the connections are solid both finger-tight and a little loose basically the box mod isn’t detecting that the heating circuit is closed regardless of whether it really is or not, and all of the common (as well as more involved) fixes for it aren’t panning out, and i wouldn’t know where to go w the electronics beyond verifying that the box mod is definitely lying to me
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Oct 4, 2019 19:36
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Ambrose Burnside posted:Sorry, no- it’s the box mod that’s the issue, i meant that i ruled out an atomizer issue by testing them with a vape that does work. I didn’t mention the big one, connectivity, whoops- i’m positive the connections are good, i hooked up the multimeter leads to either side and watched as i assembled it, the connections are solid both finger-tight and a little loose I see, and you've already torn it down and tested the obvious places on the circuitboard as well. Yeah in that case then I got nothing for ya, sorry. The error means there's a connectivity break somewhere... but it's anyone's guess where if you've tested all those things already.
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Oct 4, 2019 19:48
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welp, that's what i kinda figured. i haven't pored over the controller board too closely yet, just the big terminal joins that typically fail; we've got an apparently-decent inspection microscope at work, i'll throw it on there and poke around at the inscrutable SMD widgetboard for any loose contacts or failed joins there. i sure as poo poo wouldnt be able to fix it personally, but i bet there's a coworker who'd like to make $20 over lunch who could...
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Oct 4, 2019 20:08
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I'm working on figuring out this triangular signal generator And I have no trouble, other than not knowing what the resistor marked ROM does. Could someone clue me in? Thanks! 
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Oct 5, 2019 14:18
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It compensates for some problem with the specific opamp. I checked and it is in secton 4.12 of Art of Elecronics. Figure 4.55 is almost your circuit: H&H posted:E. Input bias current VictualSquid fucked around with this message at 15:25 on Oct 5, 2019 |
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Oct 5, 2019 15:22
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I'm wondering if there's any sort of existing modules that don't cost a fortune which can be used to give absolute position of a robot(something on the order of ~1cm or better resolution) within a bounded area, like a room or yard. Not really interested in mapping out the space like with a rotating laser rangefinder, just position reporting. I'm thinking something that uses radio/microwave triangulation from 3 or more fixed beacons? Maybe ultrasonics? Idk, maybe just an overhead camera would be a simpler idea though?
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Oct 5, 2019 22:26
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Lighthouse
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Oct 5, 2019 22:52
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a coworker took on a "forget-me-not" commission he's doing on the side- the client wants a physical-proximity-concerned watchdog timer/alert system utilizing two wirelessly-linked devices. The first device, the 'satellite', must be as small (ideally fitting in a tube of 3/4" diameter or less) and draw as little power in operation as possible, the other 'base' component just has to be "pocket/bag portable". In operation, it must perform a check sth like once every 1 to 3 seconds and alert the user if it the satellite cannot be located for several successive checks, or is too far away from the base; ideally a specific approx separation between the two would be the trigger, but an out-of-range trigger would also be acceptable. (the actual use application as i understand it is the client's child needing ot have an expensive medical device on their person and frequently losing it / forgetting it places; if this device successfully let the kid know he's forgetting his device on public transit just once it will have paid for itself and then some) - does this product already exist? it seems like fairly low-hanging fruit but i cant find any appropriate examples that have reached the market, but that's prolly down to my lovely googling as much as anything else if the above doesn't pan out: - what protocol is the best fit for this? coworker wants to go with BLE b/c the base component would need bluetooth functionality regardless to communicate with the user's phone, and the default typical connection range would be acceptable if not ideal irt sensitivity. i don't think the battery life would be all that hot if you stick a whole microcontroller in the satellite, not with the constant check-ins with the base, and the user can't really be depended on to keep the satellite part charged. I think RFID is the way to go but I know almost nothing about RFID systems, just that wikipedia says that passive tags with "a meter or two" of range aren't prohibitively expensive. Ambrose Burnside fucked around with this message at 23:38 on Oct 5, 2019 |
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Oct 5, 2019 23:36
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Is the client planning on using a smartphone as the base station with which the device will check in? As in, a phone in the possession of a child who frequently forgets and misplaces expensive things?  e: I don’t mean for this to come off as antagonistic. I work for a company which makes expensive wearables. We don’t make a product that does this per se but I’m at least aware of the challenges involved in making connected, small, battery powered devices, and those targeted to children without phones have particular connectivity vs battery life challenges. Buy the kid a carabiner. csammis fucked around with this message at 00:09 on Oct 6, 2019 |
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Oct 6, 2019 00:02
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BLE is definitely the best choice for the satellite to base station communication, and can be incredibly low power if the firmware and electronics are well designed. Using the strength of the Bluetooth signal won't be a perfect proximity measurement, or even a good one, but it'll sort of work. You can buy BLE beacons off the shelf.
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Oct 6, 2019 01:10
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Just put a Tile on it
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Oct 6, 2019 01:24
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VictualSquid posted:It compensates for some problem with the specific opamp. Thanks a bunch! I'll also get the book now.
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Oct 6, 2019 13:52
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Is there a small-volume components website online like Digikey/Mouser, but shipping from New England instead of West Coast? I need to buy some components quickly but I don't want to wait for the cross-country shipping. Closer to Boston the better.
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Oct 7, 2019 02:44
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Digikey ships from Minnesota, and it also gets to places in two days regardless of where, in North America. I frequently even order before 5pm and it gets to me in Canada before 10am the next day, it's pretty insane.
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Oct 7, 2019 03:15
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ante posted:Digikey ships from Minnesota, and it also gets to places in two days regardless of where, in North America. I frequently even order before 5pm and it gets to me in Canada before 10am the next day, it's pretty insane. Which shipper is that with? I'm sure I can't get away with the using USPS First Class but maybe Priority is decent enough.
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Oct 7, 2019 03:19
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I don't remember, just the regular one? It's even free after $100 or $200 or whatever
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Oct 7, 2019 04:56
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Zero VGS posted:Is there a small-volume components website online like Digikey/Mouser, but shipping from New England instead of West Coast? I need to buy some components quickly but I don't want to wait for the cross-country shipping. Closer to Boston the better. Arrow has free next-day shipping for all orders over $50 still so it doesn't super matter where it ships from 
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Oct 7, 2019 14:59
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Shame Boy posted:Arrow has free next-day shipping for all orders over $50 still so it doesn't super matter where it ships from Oh yeah, they have what I need but I'm $11 short of $50. What else is good to buy there? Is there such thing as like an in-line DC circuit breaker or resettable fuse for around 50v/50a? I have a lifetime of eutectic solder so not sure what other consumables I can think of.
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Oct 7, 2019 19:23
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Zero VGS posted:Oh yeah, they have what I need but I'm $11 short of $50. What else is good to buy there? Is there such thing as like an in-line DC circuit breaker or resettable fuse for around 50v/50a? I shoved the parameters into Octopart and it spat out this (and 4 other more expensive ones): https://www.arrow.com/en/products/w23-x1a1g-50/te-connectivity It's rated for 50A at 50VDC but it's also like 20 bux so
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Oct 7, 2019 19:54
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Zero VGS posted:Oh yeah, they have what I need but I'm $11 short of $50. What else is good to buy there? Is there such thing as like an in-line DC circuit breaker or resettable fuse for around 50v/50a? Nice buttons or rotary encoders, I always get like 2 or 3 whenever I do an order because you never, ever have enough of them when you want one all of a sudden.
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Oct 7, 2019 20:08
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Zero VGS posted:Oh yeah, they have what I need but I'm $11 short of $50. What else is good to buy there? Is there such thing as like an in-line DC circuit breaker or resettable fuse for around 50v/50a? I always enjoy having an assortment of potentiometers for tuning analog circuits (e.g. LED brightness) before nailing down permanent values.
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Oct 7, 2019 21:36
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Zero VGS posted:Is there a small-volume components website online like Digikey/Mouser, but shipping from New England instead of West Coast? I need to buy some components quickly but I don't want to wait for the cross-country shipping. Closer to Boston the better. Define "volume". You wouldn't happen to have a local electronics store, would you? Zero VGS posted:I have a lifetime of eutectic solder so not sure what other consumables I can think of. Wire, heat shrink, soldering iron tips, connectors, etc. kid sinister fucked around with this message at 22:00 on Oct 7, 2019 |
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Oct 7, 2019 21:57
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Hexyflexy posted:Nice buttons or rotary encoders, I always get like 2 or 3 whenever I do an order because you never, ever have enough of them when you want one all of a sudden. If you're buying rotary encoders on a whim, figure out if you want ones with or without detents. I made the mistake once of ordering ones that didn't have detents for a project where they were going to be user input hardware. Turns out they could out bounce my debounce filters and code if they were left in just the right position...which research subjects managed to do constantly. 
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Oct 7, 2019 22:03
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kid sinister posted:Define "volume". You wouldn't happen to have a local electronics store, would you? I'm well stocked on consumables, connectors might be a good idea. I bought a pile of Anderson Powerpoles a while back and I loving *hate* these things.It's like stepping on legos, but for your fingers instead. There's no room for error on the crimper, it is super hard to seat the clips, and the sparks upon connection will pit the tabs enough that it's really hard to reconnect them afterwards. One I use these up I'll switch to something like XT60 and never look back. edit: grr, so much for rush shipping, I requested an account on Arrow 5 hours ago and they still haven't replied. I can't check out as a guest either. edit 2: nevermind there's a difference between "myarrow" accounts and arrow accounts. loving tariffs though? First time I've ever been charged a tariff. On top of sales tax, added $10 to the $50. Zero VGS fucked around with this message at 01:24 on Oct 8, 2019 |
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Oct 8, 2019 00:26
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Dude. Digikey. I've also had bad experiences with Arrow.
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Oct 8, 2019 02:48
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Zero VGS posted:edit 2: nevermind there's a difference between "myarrow" accounts and arrow accounts.
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Oct 8, 2019 02:50
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I have a question. Something I need a tiny bit of help with. A little backstory: A couple of years or so ago I bought a Chinese 6J1 based tube preamp kit. I'm happy with it except for one thing. I sorely regret blindly assembling it, including the LEDs under the tubes. Recently I spotted another kit on sale for about AUD$6 so I bought it. It arrived today. I found a schematic online here: https://www.circuitlab.com/circuit/9vnehk/fever-6j1-tube-pre-amp-circuit/ It appears to be identical to the paper schematic that came with the first one. I don't have a scanner handy right now. Ordinarily I'd take them and their resistors to be totally deletable but tbqh I have a feeble understanding of how a decent chunk of this circuit works. So, can I get rid of the LEDs?
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Oct 9, 2019 23:10
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General_Failure posted:I have a question. Something I need a tiny bit of help with. I think so? It's technically a rectifier, but the current should be small enough that it wouldn't be a big impact on the rest of the circuit. Disclaimer: I'm not good at analog power electronics, so I'm working from what little I remember of first principles. Someone with experience should check.
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Oct 10, 2019 00:59
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KnifeWrench posted:I think so? It's technically a rectifier Yeah. That's where I'm a little uneasy. I mean I can see that it's running from the feed from the power diode, but I don't know if removing it will have any effect on the whole circuit, because it delves into a realm I'm unfamiliar with.
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Oct 10, 2019 01:47
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well you could replace them with diodes that don't emit light?
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Oct 10, 2019 02:07
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Splode posted:well you could replace them with diodes that don't emit light? Some sort of non-emissive light-emitting diode, you say?
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Oct 10, 2019 02:42
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