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Called it
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Nov 28, 2023 22:30
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Bad Munki posted:Called it You snuck into my house and put it there after I checked it twice just to get forum points you scamp 
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Nov 28, 2023 22:32
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longview posted:Yeah I guess I could have gotten a picture of the other side, it's a hinged blade-connector thing for coplanar board-to-board use. It's pretty likely that there is no corresponding connector for that and it's an integral punch down block for solid wire - we have something similar in canadian telecom called bix blocks 
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Nov 28, 2023 22:42
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Just spent 2 hours diagnosing a reversed capacitor. Turns out, when you rush to replace an out of stock component, you should really go look at the footprint to make sure the pins are the same. Who knew?! Surprisingly, there is no damage to the battery or the board. Even that capacitor seems fine.
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Nov 29, 2023 23:27
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Following up on my "is there a passthrough thing that just splits the ground out of an outlet and nothing else" post: the actually smart cable guy was here to fix something the idiot cable guy hosed up a little while ago and while he was here I asked him about it, and not only did he know exactly what I needed, he had one in his truck and gave it to me for free: https://tiitech.com/product/442c/  It's a passthrough outlet meant to ground coax systems, but as you can see it also just has a plain old screw terminal at the bottom left there so you can run a grounding wire out of it too. Thanks a ton, smart cable guy!  e: They also make one that seems like it's a bit smaller and just has the grounding terminal without the coax, mostly mentioning in case I need to refer back to this post later for something else: https://tiitech.com/product/442/ Shame Boy fucked around with this message at 06:19 on Dec 2, 2023 |
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Dec 2, 2023 06:16
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PRADA SLUT posted:Anyone tried throwing a benchtop kit together in a pelican case or similar to make a portable lab?
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Dec 2, 2023 09:42
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Well finally it's working, my 4A 0-230V variac. I still haven't gotten the ammeter and voltmeter (analog panel meters) but I needed it working because it's time to start the christmas lighting.
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Dec 2, 2023 14:23
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His Divine Shadow posted:but I needed it working because it's time to start the christmas lighting. We're going to see this yard on YouTube, aren't we?
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Dec 3, 2023 22:18
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Oh it's not that impressive. This is just my first try with american lighting. Planning on getting more with time to get the whole roof, really like C9s. lovely that nothing like this exist in euro land but eh I can get around that as you see. Just two 25ft strings so far. My shed in the background is running on 230V led with replaceable lamps, but I've put in a capacitive dropper in an IP67 enclosure to dim it a little, it only draws like 20 watts. So some 230V stuff exists, but not proper C9s, just big round lamps and the wiring is extremely bulky commercial stuff that's meant to be outside forever. Gonna order some tru-tones, maybe see if I can get something straight from china.
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Dec 4, 2023 08:36
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Anyone recommend a radar module I can integrate into my own PCBs? I want to build a speed gun that can measure a small objects velocity out to ~50+ feet ideally, a baseball. I've got some idea of the devices out there but it's often difficult to figure out which devices are intended for detecting/calculating velocity versus just sensing movement in general.
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Dec 12, 2023 02:36
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Popete posted:Anyone recommend a radar module I can integrate into my own PCBs? I want to build a speed gun that can measure a small objects velocity out to ~50+ feet ideally, a baseball. I was gonna recommend one of SEEED's radar units since I've used them for closer-range proximity sensing stuff before and they worked real good, but the one I could find that best meets your requirements only goes out to 10m and is also out of stock anyway: https://www.seeedstudio.com/Grove-Doppler-Radar-BGT24LTR11-p-4572.html Here it is without the onboard microcontroller, cheaper but also out of stock and with the same range: https://www.seeedstudio.com/Millimeter-wave-Doppler-radar-SYH24A-p-4392.html
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Dec 12, 2023 04:08
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Popete posted:Anyone recommend a radar module I can integrate into my own PCBs? I want to build a speed gun that can measure a small objects velocity out to ~50+ feet ideally, a baseball. InnoSenT INS-3331 24 GHz doppler radar module You talk to it over a serial UART. It sends back approaching/receding, m/s, signal strength and maybe a couple other things. It's pure doppler, it can't sense distance or angle. I doubt it can detect a small object at 50 ft. It would probably see a car, though. This radar sensor is designed for sensing room occupancy and controlling automatic doors. It is over-engineered for occupancy sensing, but it's not nearly as cool as the tech in e.g. automotive 77 GHz safety radar modules.
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Dec 12, 2023 04:17
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If you have some control over the environment, you could instead roll your own ballistic chronograph using a couple optical sensors
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Dec 12, 2023 04:46
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Garmin LIDAR-Lite v3HP $150 Straight-line lidar distance measurement (like a laser tape measure). 1cm resolution, 2.5cm accuracy, range to 40m. 1 kHz measurement rate at 10m, somewhat slower at longer distances. The fast update rate should let you compute speed. e: hmm, probably can't track a baseball
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Dec 12, 2023 05:17
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Can we expand it to a full 3D volumetric lidar system? How much are those, like $50,000?
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Dec 12, 2023 05:30
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What the gently caress, I work for Garmin in core engineering and I had no idea we sold components like this 
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Dec 12, 2023 05:34
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Most expensive I2C peripheral I've ever bought, ha ha. I should really do something with it since it's been sitting on my desk for like a year. e: Shame Boy posted:Can we expand it to a full 3D volumetric lidar system? How much are those, like $50,000? Lots of Velodyne stuff on ebay for $500 - 1,500. ryanrs fucked around with this message at 06:04 on Dec 12, 2023 |
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Dec 12, 2023 05:57
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Thanks for the recs, I will need to dig into them more to see if any match what I'd like to do. I am currently considering these ICs as well. Anyone see reasons why they might not be suitable? Infineon BGT24: 24 GHz Transceiver https://www.digikey.com/en/products/detail/infineon-technologies/BGT24MTR11E6327XUMA1/4759574 Infineon BGT60: 60 GHz Automotive Transceiver https://www.digikey.com/en/products/detail/infineon-technologies/BGT60LTR11AIPE6327XUMA2/15648396 Accion A121: 60GHz Pulse Coherent Radar https://www.digikey.com/en/products/detail/acconeer-ab/A121-001-T-R/17883300 Texas Instruments AWR1243: 76GHz Automotive Transceiver https://www.ti.com/product/AWR1243 I was leaning towards the Infineon chips as they seem much simpler than the TI. The TI might be better suited but it's a 161 pin BGA which would be a pain for me to layout/solder. Popete fucked around with this message at 06:39 on Dec 12, 2023 |
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Dec 12, 2023 06:35
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ryanrs posted:InnoSenT INS-3331 24 GHz doppler radar module This chip only tracks up to 34 km/h which is too slow even if it could pick up a baseball. I think I have to move up to at least a 60 GHz transceiver.
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Dec 12, 2023 06:51
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If you are literally measuring speeding baseballs, something like Bushnell Velocity Speed Gun might be best? I wonder what kind of antenna is inside?Popete posted:I think I have to move up to at least a 60 GHz transceiver. Negative. I think even 10 GHz doppler radar can clock pitches. Like those old gunnplexer + coffee can designs?
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Dec 12, 2023 08:33
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Well that's kind of the point of this project. I wanted to get a Pocket Radar but have been balking at the price ($300) and figured "hey maybe I can make my own for less?".ryanrs posted:If you are literally measuring speeding baseballs, something like Bushnell Velocity Speed Gun might be best? I wonder what kind of antenna is inside? I guess the issue I've been running into is I can't get a clear answer from datasheets what the feasible range and detection size is for a given IC. Also if they are subtle for velocity calculation. There's lot's of chips out there for simply detecting a persons presence or highly accurate short range distance for parking a car but I haven't come across an obvious answer for something to track a fast moving small object. Popete fucked around with this message at 09:26 on Dec 12, 2023 |
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Dec 12, 2023 09:22
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The answer to "can I make my own for less?" is almost always no. Even if you consider your own time to be worth $0 an hour.
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Dec 12, 2023 09:30
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Popete posted:Well that's kind of the point of this project. I wanted to get a Pocket Radar but have been balking at the price ($300) and figured "hey maybe I can make my own for less?". you're going to run into the "sorry this is for missiles" barrier pretty quickly.
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Dec 12, 2023 09:32
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Put replacement dimmable LEDs in my old floor standing halogen lamp. The small one works OK, but the top lamp (RS7) doesn't dim correctly, mostly flickers a bit before working normally at full strength. Also when it's turned off it looks like this: The dimmer circuit has two potentiometer/switches, one for each light. The circuit only works on the live wire, one input and two outputs labeled 60W and 300W. Neutral is tied together for both lamps and always hooked up. Based on what I have read the dimmer circuit is a leading edge dimmer and it probably doesn't work for the upper lamp because it expects a lot more current draw to function properly. What can I do here? I was wondering if I could put a suitable high wattage resistor in parallel with the top lamp to increase current draw, maybe that would make the dimmer work more as intended, maybe also help with the leakage current. e: Looks like I'd have to dissipate like 30 watts to get the dimmer to function properly so eh lets not do that. I think perhaps an alternative dimmer is needed. His Divine Shadow fucked around with this message at 17:42 on Dec 12, 2023 |
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Dec 12, 2023 09:38
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Cojawfee posted:The answer to "can I make my own for less?" is almost always no. Even if you consider your own time to be worth $0 an hour. Yes I realize the actual answer is to just buy a radar gun but this is more of a fun project for myself and I won't be surprised if I end up spending more than the actual commercial product costs. Splode posted:you're going to run into the "sorry this is for missiles" barrier pretty quickly. That's the crux of the problem I'm trying to resolve. How do commercial radar guns do this?
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Dec 12, 2023 09:43
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If you're balking at $300 for a finished unit, then hooboy, you're in for a shock when you try to get 10GHz impedance controlled PCBs
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Dec 12, 2023 16:55
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IMO, if you had all the electronics already built and debugged, then $300 is a reasonable budget for building the enclosure (couple revisions of 3D printed plastic parts).
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Dec 12, 2023 17:45
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Popete posted:That's the crux of the problem I'm trying to resolve. How do commercial radar guns do this? https://www.youtube.com/watch?v=JabrKQuMlB8 tldr: MACOM MA-7801 24 GHz gunnplexer + horn antenna e: To explain a bit, a Gunnplexer is an old-tech microwave device, based on weird diodes and precision machined metal cavities. All the RF stuff happens inside the gunnplexer module. The output signal is audio frequency and can be processed with op-amps and such. Use a microcontroller to measure the output frequency (proportional to speed). The reason you won't see radar chips with precise distance/detection ranges is because that's all in the antenna design. Or in the case of integrated on-chip antennas, they're only for short-range use. ryanrs fucked around with this message at 18:31 on Dec 12, 2023 |
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Dec 12, 2023 17:55
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Cojawfee posted:The answer to "can I make my own for less?" is almost always no. Even if you consider your own time to be worth $0 an hour. Ain't that the truth. You're not buying parts in the thousands to get that sweet, sweet quantity discount like the big boys can afford.
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Dec 12, 2023 18:39
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Gunnplexers are especially hard to get. I don't know why, but at least during my lifetime, the premier source of gunnplexers for ham radio and other hobby uses is scavenged from old equipment (police radar guns, etc). I've never seen them at general electronics distributors like Digi-Key or Mouser. Even places like Down East Microwave only had them sporadically. I don't think a MACOM gunnplexer and matching horn antenna, even on ebay, will be much cheaper than the $110 for the Bushnell radar gun. e: oh hey, Digi-Key does stock gunnplexers. Costs $54 tho. ryanrs fucked around with this message at 05:58 on Dec 13, 2023 |
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Dec 12, 2023 19:00
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Cojawfee posted:The answer to "can I make my own for less?" is almost always no. Even if you consider your own time to be worth $0 an hour. I'm currently in month 9 of my project to automate my roller blinds - I've spent at least $200 and pretending I didn't use the project to justify buying a 3D printer. I could've bought almost exactly what I wanted for $80, finished (though it would've been using very sketchy Chinese software and of questionable quality). My wife pointed out something important though when I was annoyed about having to purchase yet another motor - hobbies cost money and time, and that is kind of the point.
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Dec 13, 2023 00:53
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I'm confused about how the voltage rating of BNC connectors work. The connector specs say 500-600 volts (and usually specifies AC RMS not DC) but a lot of radiation detector equipment uses them up to 1200 volts DC or so just fine. Is it because they use DC and that's less prone to arcing? is it because of the high source impedance (typically > 1 Mohm?) Is it because of crane operator syndrome (as in the specified rating is 1/2 to 1/3 the actual design rating so people feel safe operating in what is meant to be overhead when they probably shouldn't?)
BattleMaster fucked around with this message at 15:49 on Dec 13, 2023 |
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Dec 13, 2023 13:02
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BattleMaster posted:I'm confused about how the voltage rating of BNC connectors work. The connector specs say 500-600 volts (and usually specifies AC RMS not DC) but a lot of radiation detector equipment uses them up to 1200 volts DC or so just fine. Is it because they use DC and that's less prone to arcing? is it because of the high source impedance? Is it because of crane operator syndrome (as in the specified rating is 1/2 to 1/3 the actual design rating so people feel safe operating in what is meant to be overhead when they probably shouldn't?) Are you sure the specific connectors used in those detectors are the ones with 500-600 V ratings? High-voltage BNC connectors are definitely a thing.
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Dec 13, 2023 14:58
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Stack Machine posted:Are you sure the specific connectors used in those detectors are the ones with 500-600 V ratings? High-voltage BNC connectors are definitely a thing. The "high-voltage BNC connectors" you're thinking of are probably actually either MHV or SHV connectors, and I'm certain BattleMaster knows what those are cuz they taught me what they were in the first place 
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Dec 13, 2023 15:29
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Yeah, "high-voltage BNC" is a phrase that is sometimes used to refer to MHV. And it doesn't give the right idea either - BNC males can mate with MHV females but that's not actually intended, and this and other safety issues with MHV is why SHV was created. How do I know I'm not dealing with MHV connectors here? Because in spite of the unintended mating compatibility they actually look different enough that you can visually distinguish them if you know what they are meant to look like. Actual honest-to-goodness BNC connectors intended to mate with real BNC connectors are something I've never found with a higher voltage tolerance but lots of G-M counters use them even though they operate at higher voltages than the connector is rated for.
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Dec 13, 2023 15:48
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I meant ~1.5kV by high voltage, not multiple kV like MHV. I didn't survey datasheets or anything but I know I've seen 1.5kV BNC leads advertised. Sure that doesn't leave any margin, but you mentioned it's high impedance so the consequence of a breakdown is that it doesn't work not that it burns down.
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Dec 13, 2023 19:25
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That got me curious so I went to go find one and came across this: https://au.element14.com/mh-connectors/bncccl1mrg58/test-lead-1m-1-5kv/dp/3153502 1.5KV RMS and both the listing and the PDF drawing just say "BNC", so in conclusion who the hell knows
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Dec 13, 2023 19:35
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Outside of the world of sketchy test lead vendors the highest operating (vs dielectric withstanding) voltage Amphenol seems to offer for BNC jacks is 1kV RMS. Assuming that's for sine waves that suggests you could get to 1.4kV DC without striking an arc. They're not advertised for DC so someone using them for that would have to do their own qual, but it kind-of adds up. I guess what I'm saying is that, if 1kV RMS is the best rating that can be had in BNC I believe both of these are factors: BattleMaster posted:Is it because they use DC and that's less prone to arcing? is it because of the high source impedance (typically > 1 Mohm?) DC because there is no sqrt(2)x-higher peak voltage to worry about and the high impedance because it limits the amount of damage an arc could do if it did manage to form. Stack Machine fucked around with this message at 08:13 on Dec 14, 2023 |
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Dec 14, 2023 08:02
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Be aware there are lots of "voltage ratings". Working/operating voltage, dielectric strength, breakdown voltage, dielectric withstand, etc. Coax connectors can be especially weird. Working/operating voltage is sometimes actually based on temperature rise, assuming a matched load (and also depends on frequency). In a couple cases (for cable-mount connectors only) the voltage ratings were based on weird cases like a worst-case VSWR and forward power.
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Dec 14, 2023 20:54
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So I did a survey of BNC connectors, and even among just Amphenol BNC connectors there are datasheets* that don't list the voltage rating at all, a bunch that list 500 VRMS, some that list 1000 VRMS, and some that list 1500 VRMS. So clearly I didn't do a thorough enough survey. *by "datasheet" I mean they all are one-page drawings of the parts and recommending mounting if applicable, but sometimes they have a list of figures in the corner and sometimes they don't.
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Dec 15, 2023 14:06
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