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Stan Taylor posted:I mostly just want to have a crafty hobby, but I'd like to eventually make a device that would trigger when my cat does something and take a picture and upload it to either a twitter account or email ot to me or something. maybe add a laser pointer or treat dispenser to goad the cat into doing cute stuff. One of those useless box kits does sound like a fun starting project and from what I understand they're pretty easy to make so yeah go with that. As far as your cat sensor, you could probably make that with a raspberry pi and the camera attachment (there's software that will let you trigger when the camera detects movement), then point it somewhere the cat likes. Once you get that working it's pretty easy to add other things to the r-pi later so if you wanna rig up some kind of laser pointer wiggler or something you can add it, etc.
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Sep 22, 2017 16:40
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Quick question. In the usual solar powered LED garden string lights, like the Xmas, Halloween etc ones, is the little control board in the solar unit just used for light sensing / light power control or is it also used for charging somehow? I've got so many wrecked solar lights around. I just want to do something silly like connect a 0.9+v -> 5v buck converter to to it (because I have one) and run an esp8266 as a meshnet node maybe for no real reason that I can think of. I might set it up to wake up occasionally and send the current battery voltage to something. See how long it can last.
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Sep 25, 2017 03:31
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I'd just like to say thank you to everyone that helped me decide on a hot air/iron combo station and fix my phone! I almost feel spoiled now that cords don't wiggle and fall out, let alone restoring USB connectivity. No, scratch that. This soldering station is better. After only using irons before, I really feel spoiled that I can just select a temperature and the tool can reach it in seconds! Why was I screwing around with just an iron before? I wish I had this thing back when I had to reattach a TNC lug to a wifi router board.
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Sep 25, 2017 04:00
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General_Failure posted:Quick question. In the usual solar powered LED garden string lights, like the Xmas, Halloween etc ones, is the little control board in the solar unit just used for light sensing / light power control or is it also used for charging somehow? Pull one apart and post up pictures
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Sep 25, 2017 04:57
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kid sinister posted:I'd just like to say thank you to everyone that helped me decide on a hot air/iron combo station and fix my phone! I almost feel spoiled now that cords don't wiggle and fall out, let alone restoring USB connectivity. No, scratch that. This soldering station is better. After only using irons before, I really feel spoiled that I can just select a temperature and the tool can reach it in seconds! Why was I screwing around with just an iron before? I wish I had this thing back when I had to reattach a TNC lug to a wifi router board. Moving from a crummy basic low-end Weller to something that can actually measure accurate temperatures and reach them quickly was absolutely like night and day for me too, yeah. Glad your project went well buddy 
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Sep 25, 2017 05:24
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General_Failure posted:Quick question. In the usual solar powered LED garden string lights, like the Xmas, Halloween etc ones, is the little control board in the solar unit just used for light sensing / light power control or is it also used for charging somehow? BigClive has pulled apart tons of solar lights and if i remember correctly all the ones that just used NiMH batteries (so pretty much all of them) just had the solar panel strapped right to the battery and trickle-charged it, because you can beat the poo poo out of NiMH without hurting them.
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Sep 25, 2017 05:25
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General_Failure posted:Quick question. In the usual solar powered LED garden string lights, like the Xmas, Halloween etc ones, is the little control board in the solar unit just used for light sensing / light power control or is it also used for charging somehow? Bigclivedotcom has a bunch of solar light hacking/teardown videos on Youtube, might be worth checking out. https://www.youtube.com/watch?v=VAsyVk0ZIqQ https://www.youtube.com/watch?v=yHJOFIb32XY
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Sep 25, 2017 05:27
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Neat! Thanks. No matter how hard I stared at the schematic of the solar controller and the board I just couldn't work out what it did with the battery, because whatever it was passed through the controller first, but was on the other side of the inductor to the LED(s). I cobbled together something out of a string light one a little while ago. It managed to power the buck converter for about 10 seconds with no load lol. I really should order a slightly larger solar cell from AliExpress or something. It's just for messing around so it's no big deal. I'm mostly just using broken things which I'd otherwise throw away anyway.
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Sep 25, 2017 06:38
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ate all the Oreos posted:BigClive has pulled apart tons of solar lights and if i remember correctly all the ones that just used NiMH batteries (so pretty much all of them) just had the solar panel strapped right to the battery and trickle-charged it, because you can beat the poo poo out of NiMH without hurting them. Yep. I've taken apart a bunch of those things for projects in the past, and it's usually just the solar cell, a diode, and the battery all soldered together, and sometimes some kind of very simple comparator dealy that turns the LED on when the solar cell voltage drops below some point. No charging logic. A little 3x3" solar cell can't provide enough current to damage a NiMH battery anyway.
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Sep 25, 2017 22:03
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The cheap-rear end microwave radar thingies can't measure distance, can they? I want something to measure how far a person is from the sensor, but ultrasonics wouldn't work very well either at these distances, up to 4-5m. It's just for dicking around so I wouldn't want to spend more than a few bucks which makes this tricky 
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Sep 27, 2017 10:37
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mobby_6kl posted:The cheap-rear end microwave radar thingies can't measure distance, can they? I want something to measure how far a person is from the sensor, but ultrasonics wouldn't work very well either at these distances, up to 4-5m. It's just for dicking around so I wouldn't want to spend more than a few bucks which makes this tricky Laser rangefinder?
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Sep 27, 2017 17:31
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Stabby McDamage posted:Laser rangefinder? Last time I checked, even the ones of those advertised as being built down to a price for hobbyist use were running into the low-$100 range. Measuring short distances with lasers requires pretty clever fast sampling stuff from what I understand so it's still up there. Shame Boy fucked around with this message at 17:50 on Sep 27, 2017 |
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Sep 27, 2017 17:46
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If you only need one of them and they don't have to be super accurate, maybe buy a lovely used Kinect from a pawn shop or ebay and do something in software? I've actually been meaning to play around with the one I got second hand for $20 for a while but I can't really think of anything too interesting to do with it
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Sep 27, 2017 17:49
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ate all the Oreos posted:Last time I checked, even the ones of those advertised as being built down to a price for hobbyist use were running into the low-$100 range. Measuring short distances with lasers requires pretty clever fast sampling stuff from what I understand so it's still up there. Maybe you could try to hack one of the hand-held units like this, some of which are dirt-cheap on ebay now. You could also look at nicer ultrasonics -- there are ones better than the two-eyed HC-SR04 that you see everywhere. More broadly, could you share your end-goal? Maybe there's another sensor or trick that could work instead.
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Sep 27, 2017 19:09
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Stabby McDamage posted:Maybe you could try to hack one of the hand-held units like this, some of which are dirt-cheap on ebay now. Huh I had no idea these existed, neat
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Sep 27, 2017 19:19
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mobby_6kl posted:The cheap-rear end microwave radar thingies can't measure distance, can they? I want something to measure how far a person is from the sensor, but ultrasonics wouldn't work very well either at these distances, up to 4-5m. It's just for dicking around so I wouldn't want to spend more than a few bucks which makes this tricky Sharp makes an IR rangefinder that works 1 - 5.5 meters: Sharp GP2Y0A710YK0F Long Range IR Distance Sensor. Seems to be around $20 depending on where you buy it, which might be more than a few bucks, but it's easier than having to hack a thing.
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Sep 27, 2017 19:47
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Stabby McDamage posted:Maybe you could try to hack one of the hand-held units like this, some of which are dirt-cheap on ebay now. They're available in retail stores for under $100 too now. http://www.sears.com/craftsman-accutrac-laser-measuring-tool/p-00948277000P?plpSellerId=Sears&prdNo=1&blockNo=1&blockType=G1
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Sep 27, 2017 20:05
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You're looking for a time of flight sensor. https://www.adafruit.com/product/3317
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Sep 27, 2017 20:09
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Ok, thread, I'm looking for a speed sensor. I've got a motorcycle that's vibrating all my hall effect stuff to death, so I would like some kind of doppler sensor. Are there cheap ones? Speeds are normal vehicle speeds, say 0-100mph. babyeatingpsychopath fucked around with this message at 22:39 on Sep 27, 2017 |
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Sep 27, 2017 22:31
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babyeatingpsychopath posted:Ok, thread, I'm looking for a speed sensor. I've got a motorcycle that's vibrating all my hall effect stuff to death, so I would like some kind of doppler sensor. Are there cheap ones? GPS would work for that depending on the accuracy you need
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Sep 27, 2017 22:44
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If you were looking at rotations before, why not a tachometer?
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Sep 27, 2017 23:00
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JawnV6 posted:If you were looking at rotations before, why not a tachometer? Getting the rotational input is tricky. I have to get from a wheel to the speedo. I have no direct connection to the wheel. There's an rear end-ton of vibration. The environment isn't very friendly with whatever is on the road. Hall effect sensors work OK, but when I ride down a dirt/gravel/bumpy road, then even the best mounting solution for the sensor (rigid and close) rattles all over the place. If I had something designed for this, it'd be far easier, but I'm trying to retrofit something from 1976 when technology didn't exist yet and transistors were exciting enough that they were worth mentioning in the marketing. Would GPS work well enough as a direct replacement for a speedo? Is speedo lag a problem? How about the odometer function; wouldn't it be worthless in a tunnel or, as is found around here, under heavy trees in the rain?
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Sep 27, 2017 23:14
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Alternating white black stripes being detected by a light sensor of some kind? Like a laser tachometer?
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Sep 27, 2017 23:57
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babyeatingpsychopath posted:Ok, thread, I'm looking for a speed sensor. I've got a motorcycle that's vibrating all my hall effect stuff to death, so I would like some kind of doppler sensor. Are there cheap ones? Doppler will probably be very unreliable since it would only give you good speed readings when pointed at something stationary that you're driving right towards. The ground is basically flat and will most likely give you a very noisy reading and other vehicles are usually stationary relative to your vehicle. But you can definitely get cheap 10 GHz Doppler radars if you want to play with one, just search for Doppler radar on ebay. Range will normally be very poor though. Sagebrush did a similar thing earlier this year by tapping off the ignition circuitry to get a tachometer reading and something else to get the speed - I think that bike had a speedometer, and with tach+speed a gear estimate could be made). If you can figure out what gear the bike is in (maybe hall effect would be easier to mount then?, or make something to detect gear change and direction and keep track of the gear in software?) and make a tacho then a speedometer should be fairly easy. Comedy option: Use an accelerometer and just integrate the output.
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Sep 28, 2017 06:46
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babyeatingpsychopath posted:Getting the rotational input is tricky. I have to get from a wheel to the speedo. I have no direct connection to the wheel. There's an rear end-ton of vibration. The environment isn't very friendly with whatever is on the road. It's a '76 Gold Wing, right? Shouldn't that have a cable drive from the front wheel? My '88 Hawk GT uses a cable drive, and this is what I designed. It works perfectly up to 95mph indicated, and theoretically (electrically) should work up to 280~ mph but I haven't been able to test that yet.  Mostly 3D-printed parts, one bearing, a C-clip, and a machined aluminum threaded piece to screw onto the stock cable (M12x1mm thread, very strange and hard-to-find -- I would have liked to just cut up a bolt but had to make it on a lathe instead). The cable spins a rotor with a small rare-earth magnet glued into it and the hall effect sensor stuck into the side reads the pulses. I haven't had any problems with vibration or noise. Note that you want to use a sensor with some built-in hysteresis. The bevel gear drive in the front wheel has a ratio of 3:8 and my front wheel has a circumference of around 1800mm, so that works out to around 4300 RPM/70Hz at 100mph. Well within the scope of what a simple microcontroller using interrupts can handle. I'm not sure what you are trying to accomplish with a doppler sensor -- reading the speed of the road going by or something? That sounds like an incredible headache. IMO the reasonable ways of getting speed on the motorcycle are: 1) GPS module - easy - accurate at moderate to high speeds - mostly software, no bike mods needed - can be slow to update - lost signal = no data - odometer not particularly accurate 2) glue magnet on front wheel, mount sensor on fork - accurate measurement of speed and distance - instantaneous updates, quite reliable - requires new wire run and modification to wheel - sensitive to dirt and muck 3) do the thing I did with a custom cable drive - same advantages as above - not affected by dirt and muck - doesn't require any modifications to bike - requires more design work + machining - a little bulkier There are plenty of other ways you can think of to do this, like optical sensing on the sprocket, or a combination of a tachometer and a gear indicator, but I think they all have far more problems than just sticking a magnet on one of the easily accessible spinny parts. Sagebrush fucked around with this message at 07:28 on Sep 28, 2017 |
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Sep 28, 2017 07:07
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Sagebrush posted:I'm not sure what you are trying to accomplish with a doppler sensor -- reading the speed of the road going by or something? That sounds like an incredible headache. IMO the reasonable ways of getting speed on the motorcycle are: 1) Ruled out because of your reasons 2) Is currently in the process of not working 3) has a broken cable drive in the front wheel hub, which is why i ditched the cable in the first place. The hub is ovaled out so the gears don't engage so the bit that should turn the cable doesn't. I could pretty much pay someone to follow me and radio my speed to me for the cost of a new front hub. 4) It's a shaft drive, so no sprocket. Maybe I just need a far far more robust mounting solution than a 2" piece of 1/4" thick aluminum angle bolted to the fork with a pair of m6 bolts.
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Sep 28, 2017 11:08
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babyeatingpsychopath posted:Yeah, a doppler sensor mounted to the bottom of the bike should just read the road surface going by. Seems very straightforward, electrically. I haven't done it, but I've always considered tapping the final drive and using a hall sensor to read the gears turning. That in combination with something like a SpeedoHealer should work. However if you're gonna do this you might as well just fix the loving front hub. They're not that expensive are they? I mean I bought a whole 76 GL1000 for like $300. Honestly your best bet is still probably a good phone mount. Use a GPS speedo app and be good to go. e: oh poo poo this isn't the motorcycle questions thread.
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Sep 28, 2017 19:46
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Thanks everyone. There definitely a couple of workable options I haven't considered before, and if I were to do this seriously then $30-50 wouldn't be a huge deal. What I'm trying to do is just determine how far away a person is standing from my gadget. A simple distance measure obviously has its downsides such as only detecting the one closest person in a narrow zone but would've been good enough for a prototype. A machine vision solution would probably be best but also kind of overkill at this point.ante posted:You're looking for a time of flight sensor.
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Sep 28, 2017 21:08
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GnarlyCharlie4u posted:e: oh poo poo this isn't the motorcycle questions thread. Yeah, so this is the electronics thread, and now I just want a doppler sensor for no reason at all, with no application in mind whatsoever, that can measure from 0 to 50m/s, resolution .5m/s, distance 1m. If anyone knows of a prebuilt solution for less than $50, or individual parts for less than $20, chime in.
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Sep 28, 2017 21:42
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mobby_6kl posted:Thanks everyone. There definitely a couple of workable options I haven't considered before, and if I were to do this seriously then $30-50 wouldn't be a huge deal. What I'm trying to do is just determine how far away a person is standing from my gadget. A simple distance measure obviously has its downsides such as only detecting the one closest person in a narrow zone but would've been good enough for a prototype. A machine vision solution would probably be best but also kind of overkill at this point. For that price you could opt for a slightly better ultrasonic sensor: https://www.pololu.com/category/78/sonar-range-finders The '0' models have fairly wide beam angles, to boot.
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Sep 28, 2017 21:52
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OK I found the peripheral i needed, the ESP32 has a "RMT" thing that lets you set up a waveform with bit times and such Now to debug w/o an oscilloscope ;_;
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Oct 1, 2017 20:59
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I have a rice cooker that uses a CR2354 cell to keep the clock going when the power is off. The battery has died. The existing cell is one with spot-welded tabs that is soldered onto the PCB:  I've broken off the welds and I was hoping that i could drop in a standard button cell and epoxy it into place, but that didn't work Can I use one of these and solder wires onto the tabs? 
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Oct 1, 2017 23:30
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spog posted:I have a rice cooker that uses a CR2354 cell to keep the clock going when the power is off. The battery has died. RIS reveals they’re the same chemistry so it will work. Make sure you physically secure it because you don’t want it just hanging by the wires.
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Oct 1, 2017 23:55
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Malcolm XML posted:OK I found the peripheral i needed, the ESP32 has a "RMT" thing that lets you set up a waveform with bit times and such The MicroUSB port came off my ESP32 board about a week ago. Couldn't save the connector. The pins were brittle and snapped when I tried to straighten them. On the bright(???) side my Raspberry Pi Zero is dead and the port looks the same. It's my fault for forgetting my rule. Always, always give the solder a touch up on the connectors of module boards, and if possible superglue the drat thing to the board too. My ESP32 board is one of those ones that takes an 18650 battery on the back. It's functionally useless for mounting on anything but makes a good project board for experimenting with.
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Oct 3, 2017 02:58
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General_Failure posted:The MicroUSB port came off my ESP32 board about a week ago. Couldn't save the connector. The pins were brittle and snapped when I tried to straighten them. On the bright(???) side my Raspberry Pi Zero is dead and the port looks the same. It's my fault for forgetting my rule. Always, always give the solder a touch up on the connectors of module boards, and if possible superglue the drat thing to the board too. I learned the hard way after my academic advisor snapped multiple micro USB connectors off of prototype equipment that you always get the ones that have 4 mechanical stabilization pins because the two pin versions just torque around the axis between the pins and no, I can't just "stick it back on" after you've torn the pads off of the board. That being said, if you have something with an iffy mechanical connection, my recommendation would be to use a copious amount of a 2-part epoxy after covering all entrance holes to the connector with tape because it's much thicker than super glue (which I've also tried) and provides far more structural support. That being said, if you're not certain about the conductive properties of an epoxy you want to use in this application, mix up a small amount, let it cure, and check the resistance with a multimeter.
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Oct 3, 2017 04:53
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Platystemon posted:RIS reveals they’re the same chemistry so it will work. Thanks, much appreciated.
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Oct 3, 2017 14:41
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Can anyone recommend me a decent pre-assembled 12V Class-D / T-amp / whatever you want to call it that I can get soon or immediately? I wanna build a little boombox to take camping next week and I don't really have time to order parts and build one. Bonus points if it does bluetooth. Edit: I know Lepai makes a ton of stuff but I have no idea what is good and what isn't. GnarlyCharlie4u fucked around with this message at 23:20 on Oct 3, 2017 |
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Oct 3, 2017 23:13
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This is 12v 3a and works great with a chromecast audio to my non-audiophile ears.
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Oct 3, 2017 23:38
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Tres Burritos posted:This is 12v 3a and works great with a chromecast audio to my non-audiophile ears. I'm usually super picky about my stereo quality but somehow I doubt that jamming to tunes while super drunk in the middle of the woods is going to require the utmost in audio fidelity. Can y'all recommend anything a touch more powerful? I've got my eyes on a number of Amazon purchases for next day delivery but I have literally no idea which ones are proven legit and which ones are complete bullshit. Edit: basically I'm gonna have a dozen 12v UPS batteries that I can wire in any configuration to feed this amp and probably only need it for about 24h of operation. Also some reviews say it's good up to about 30v but still sounds like poo poo. I can't find much else beyond that. GnarlyCharlie4u fucked around with this message at 05:23 on Oct 4, 2017 |
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Oct 4, 2017 05:02
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poeticoddity posted:I learned the hard way after my academic advisor snapped multiple micro USB connectors off of prototype equipment that you always get the ones that have 4 mechanical stabilization pins because the two pin versions just torque around the axis between the pins and no, I can't just "stick it back on" after you've torn the pads off of the board. When buying things from China one does not always have the choice of parts used. Rule of thumb is they will use the worst drat connectors available. Also *gasp* how did you guess it was the two stabilisation pin type? I was "lucky" in that the soldering was so poor the only loss from the board was part of one of said pin's pads and the trace stub for the N/C pin. On the rest the solder just separated from the connector. Sadly I think I'll end up scrapping that ESP board. It has some strange behaviour when supplying power through VCC and the data through RX and TX (and 0v through GND of course). I can't quite diagnose it and don't care enough to try. I might see if I can get a small pack of micro USB connectors on AliExpress though to have a shot at the connector at some point. quote:
Interesting. I wouldn't have considered epoxy. I mean I've tried both epoxy and superglue in a similar yet totally unrelated circumstance and the epoxy did last longer. It was to hold the latches on the quarter windows on my car. For some idiotic reason the latches are adhered to the glass. Adhesives just don't work long in Australia. Epoxy lasted longer for sure. Short term superglue held better. So well in fact that at one point it took some glass with it. Back on topic. I received a couple of adjustable buck converters today that I ordered a while back. Variable output voltage and input can vary between above / below output. When I get around to it I'm going to try one out with the solar car trickle charge panel I have. I want to connect it to one of the USB power banks. No real reason. Just because. My little experiments with the garden light panels worked too, considering the poor state they are in. One is a lightly modified string light solar unit which I just moved the output wires to the battery. No lights attached. The other is a little stranger. I have a small panel from the top of a solar bug zapper. It's in poor condition but I managed to get some voltage through it with some new wires in a different location. The panel has been attached to the remains of a little single garden light which takes an AAA cell. I'm feeding the solar cell through it's builtin IC too. The only reason I'm doing it is I haven't seen a single design where the + of the panel connects to the battery +. It always goes via the IC. It's all just pointless goofing around, but why not. I've always had an interest in solar but never really explored it.
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Oct 5, 2017 02:10
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