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Current through data lines will be negligible. To find current through the resistors, plug the voltage over both of them, and then total resistor value (in series!) into Ohm's Law.
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Sep 14, 2017 02:24
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 The wimpiest resistors you’re likely to use are good up to a sixteenth of a watt. Use the formula at 5:30 on the circle. No resistor with value of 400 Ω or greater will be forced to dissipate more than a sixteenth of a watt on a five‐volt circuit.
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Sep 14, 2017 03:18
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Great, thanks for the pointers. The resistors I was looking at are rated for 1/10th of a watt so they'll be good to go.
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Sep 14, 2017 03:37
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I asked this in the Arduino thread but there's been no ideas: I need to clock out data, basically OOK, at a certain rate for a certain length. I'm currently doing it by having a timer interrupt fire on the transition times and an ISR then changes the pin state or turns off the timer when all data is processed Is there a hardware peripheral that I can just say: here's the data here's the timing I need deal with it rather than consuming a timer ?
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Sep 14, 2017 15:58
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Malcolm XML posted:I asked this in the Arduino thread but there's been no ideas: SPISetClockDivider?
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Sep 14, 2017 22:10
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Welp, the pins on that micro USB connector are underneath the connector itself and have these teeny tiny resistors right next to them, so I can't reach them with the iron. What is everyone's opinion on dual iron/hot air soldering stations?
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Sep 14, 2017 22:39
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kid sinister posted:Welp, the pins on that micro USB connector are underneath the connector itself and have these teeny tiny resistors right next to them, so I can't reach them with the iron. The 852 clones? The design works well enough. Some are underpowered. Some have bad qc. That said I much prefer the stand alone 858 design, like Oreos linked. If you compare the cord you'll see it's noticably thinner. This is because the 852 style has a pump in the base and has to shove air down the hose, where as the 858 style has a fan in the hand piece. This makes the 852's cord much stiffer, and as the pump has to work much harder, it's also substantially louder. I haven't seen any combo stations using the 858 style yet, but they may be out there.
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Sep 14, 2017 23:56
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Not slow enough, the bit time for this is 500usec so like 2kbps Also I'm not limited to an Arduino it's just what I have lying around. On the raspberry pi I'm using the pwm hardware via pigpio's awg functionality which works but is really complicated
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Sep 15, 2017 00:03
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Malcolm XML posted:I asked this in the Arduino thread but there's been no ideas: Do you mean a UART? Is this just dumping bits? High-for-on, low-for-off with no other encoding? Extra clock lines? Some kind of RLL so you don't just have a huge number of off- or on-bits and maybe wonder if the line is dead/shorted? I think we need more information to make a call. Honestly, "consuming a timer" and "an ISR" is about as simple as digital data output gets.
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Sep 15, 2017 00:59
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Malcolm XML posted:Not slow enough, the bit time for this is 500usec so like 2kbps In that case, why not just bitbang? Does the timing have to be accurate while being slow?
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Sep 15, 2017 02:05
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Aurium posted:The 852 clones? The design works well enough. Some are underpowered. Some have bad qc. I was thinking about this one. Good or bad idea?
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Sep 15, 2017 04:09
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babyeatingpsychopath posted:Do you mean a UART? Is this just dumping bits? High-for-on, low-for-off with no other encoding? Extra clock lines? Some kind of RLL so you don't just have a huge number of off- or on-bits and maybe wonder if the line is dead/shorted? Basically it's using an RF transmitter to turn on and off at a certain rate (on off keying) that's currently aboit 2kbps Nothing fancier than that. Can't use UART since that had a specific packet format and this protocol I'm stuck using has a bizarro encoding that makes it basically necessary to bang it out.
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Sep 15, 2017 11:24
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If dedicated hardware is that desirable, you could just make your own out of a ATtiny85 or something. Serial in, bitbang out, maybe 10 lines of code?
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Sep 15, 2017 14:03
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kid sinister posted:I was thinking about this one. Good or bad idea? That's the handpiece style I prefer. There's a good number of reviews, and a decent star rating, so it probably won't arrive broken. Unfortunately it doesn't tell you wattage, but most don't. I don't see any real red flags, so it looks fine. No matter what one(or style) you get, check continuity between the metal bits of the hot air gun and the plug. They've been known to occasionally come dangerously wrong. (Shroud connected line voltage)
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Sep 15, 2017 17:22
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Aurium posted:No matter what one(or style) you get, check continuity between the metal bits of the hot air gun and the plug. They've been known to occasionally come dangerously wrong. (Shroud connected line voltage) Ground connected to hot??? What a shocking surprise! PS now that I've opened up my phone, fought with the micro USB's connector acting like a big heat sink for my iron and put my phone back together with just 2 out of 23 screws, the port charges again with every cable I got. I'm posting from it now actually. Sometimes technology is a mystery to me. I'm still ordering that hot air station and fixing this though. kid sinister fucked around with this message at 21:17 on Sep 15, 2017 |
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Sep 15, 2017 21:12
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Got an IC question: are there any chips that can be utilized (probably with a few external caps/inductors) to take an unregulated D.C. input voltage and generate a regulated +V and -V output? I am looking at building a very simple PWM inverter for demonstrating three-phase measurements on a power quality meter without needing a real three-phase power source. (I know I could also just take an offset PWM signal and use a high-pass filter.) Aside: I found that Digikey sells 4.5kV 3kA thyristors for only about $800 each.  http://www.pwrx.com/pwrx/docs/tdk4_30.pdf I'd love to construct a 4160V soft-starter that was run off a little Arduino. Of course you'd need a separate gate firing board you're not going to connect an IO pin directly to the gate. Three-Phase fucked around with this message at 14:28 on Sep 17, 2017 |
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Sep 17, 2017 14:02
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Three-Phase posted:Got an IC question: are there any chips that can be utilized (probably with a few external caps/inductors) to take an unregulated D.C. input voltage and generate a regulated +V and -V output? What is your power source? Your best bet would probably be a pair of switchmode converters, setup one as a regular, and one inverting output. If you need minimal power, you could have a railsplitter op-amp circuit, and a pair of linear regulators, one positive one negative. If you have 2 isolated voltage sources(batteries, transformer windings, even most power bricks), you can series them, declare the middle point ground, and go from there. You can use a single transformer based switchmode converter, with a center tapped secondary winding (or 2 in series). Lowest part count, considering that everything above is basically twin circuits. Down side is the large amount of work required to actually do this.
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Sep 17, 2017 16:44
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How crazy would it be to keep the gas shut off at the wall and just relight the pilot lights when you use it?
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Sep 17, 2017 17:37
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Corla Plankun posted:How crazy would it be to keep the gas shut off at the wall and just relight the pilot lights when you use it? I don't know where you are, but the gas valves (and water valves!) used for residential natural gas (and water) service in homes in the US aren't made to be used a lot. They will quickly wear out and begin to leak if you repeatedly turn them on and off. And due to housing codes you usually can't put in different [manual shut-off] valves,,,,, legally. For gas service, you can only use the ones specified. There are cheap solenoid valves that you light look into. Usually operate with 12v dc or 115v ac. Prices are $20 - $50. For natural gas I'd be inclined to go with one of the name-brand $50 ones.
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Sep 17, 2017 19:33
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If your hobby project involves gas then perhaps reconsider.
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Sep 17, 2017 22:41
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Don't rig up homemade stuff to a natural gas system
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Sep 18, 2017 03:20
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Aww, but a smoking loving crater is the best place to start a "goons pissing in the hole" story!
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Sep 18, 2017 07:57
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Stabby McDamage posted:If dedicated hardware is that desirable, you could just make your own out of a ATtiny85 or something. Serial in, bitbang out, maybe 10 lines of code? Yeah I might end up doing that but I was hoping that this was already a widely used peripheral that I had no idea about
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Sep 18, 2017 16:27
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The issue is, if 10 electrons fart and your Arduino / microcontroller reboots or does strange things while hooked up to your lighting or outdoor sprinkler, nothing much happens. If the same happens while hooked up to a gas system, you might asphyxiate or blow up your house/kids/cat.
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Sep 18, 2017 16:44
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Please make sure your homeowners insurance knows about this so they can cancel your policy early
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Sep 18, 2017 19:23
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Idk where the natural gas talk came from, but if you absolutely must homebrew something, please use a furnace ignition controller with flame rectification sensing. They aren't super expensive, and will prevent the gas valve from dumping gas into whatever enclosed space. The part number for the kit is Y8610U4001/U Or Honeywell makes a variety of controls that will be far more reliable https://customer.honeywell.com/en-US/Pages/Department.aspx?cat=HonECC+Catalog&category=Gas+Ignition+Controls&catpath=1.2.10.3
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Sep 18, 2017 23:06
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Also let me tell anyone that if you have to modify a gun to fit the bigger pew pew bullets in it make sure you only use certified pew pew bullets, and always wear safety glasses when you look down the barrel
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Sep 19, 2017 03:25
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Three-Phase posted:Got an IC question: are there any chips that can be utilized (probably with a few external caps/inductors) to take an unregulated D.C. input voltage and generate a regulated +V and -V output? If you only need moderate amounts of power and the output can have some ripple, you can get ICs that have a pair of charge pumps that'll generate +/- supplies from one DC input.
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Sep 19, 2017 05:36
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Three-Phase posted:Got an IC question: are there any chips that can be utilized (probably with a few external caps/inductors) to take an unregulated D.C. input voltage and generate a regulated +V and -V output? A pair of Buck or Boost convertors would work, and they only need a couple of external components if you use a decent controller edit: you'll need a scope though
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Sep 19, 2017 10:03
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I'm interested in learning some simple electronics, and have a project for myself. I was hoping to make a status LED that ties into my Nest thermostat (remotely). Basically just a blue LED for AC is running, green for AC on, but not running, orange for heat on, but not running, and red for heat is running. I was thinking of trying a Espruino Pico that my coworker recommended to help control the LEDs, but that's about all I know. I found that I can't get those statuses from IFTTT, so I'm not sure if I can use the Nest to get these statuses in the first place.
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Sep 19, 2017 16:45
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IUG posted:I'm interested in learning some simple electronics, and have a project for myself. I was hoping to make a status LED that ties into my Nest thermostat (remotely). Basically just a blue LED for AC is running, green for AC on, but not running, orange for heat on, but not running, and red for heat is running. I was thinking of trying a Espruino Pico that my coworker recommended to help control the LEDs, but that's about all I know. I found that I can't get those statuses from IFTTT, so I'm not sure if I can use the Nest to get these statuses in the first place. The Espruino has a triple threat of being really expensive, not so well known (limited community support), and way more power and complication than you need. I'd pick up an Arduino micro or nano clone or something similar. Don't pay more then tenbux or so, then you won't feel bad when you burn it. Buy a couple, and also some sensors, and then run through some tutorials.
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Sep 19, 2017 18:11
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Look into the ESP8266 boards, especially the nodeMCU. The form factor is similar, and will connect to the internet / nest. Here's an esp8266 based project that interfaces with the nest API https://github.com/jvsd/nest/blob/master/remote_temp.py
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Sep 19, 2017 19:27
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rawrr posted:Look into the ESP8266 boards, especially the nodeMCU. The form factor is similar, and will connect to the internet / nest. Yeah go with ESP since this almost definitely needs networking and networking an arduino (or leaving it hooked up to serial all the time) is a pain in the rear end and not really something worth doing your first time out
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Sep 19, 2017 21:02
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Are there any recommended kits or tutorials for an absolute loving total beginner? I've decided I want to get a soldering iron and maybe a dremel tool and gently caress around with weird robot poo poo alongside software stuff on a raspberry pi. I was looking into beginner arduino kits but might be go for one of those all in one kits that comes preprogrammed and you just have to screw it together and solder a few bits.
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Sep 21, 2017 04:21
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If I need 5V for my MCU, some sensors and leds, and 12V to drive a stepper motor (using a driver board like the DRV8825 ones), what would be the best power supply design? 1) Separate 12V and 5V switch mode power supplies 2) One 12V SMPS and step down to 5V with one of those step down dc/dc modules Having a separate power supply for the steppers seems like the most often recommended solution, but I'm not exactly sure of the reasons why. Is it because of the possible transients from the steppers?
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Sep 22, 2017 01:59
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rawrr posted:Having a separate power supply for the steppers seems like the most often recommended solution, but I'm not exactly sure of the reasons why. Is it because of the possible transients from the steppers? That’s why I would consider it. Yeah the transients may not be an issue and there are other ways of handling them, but separating the power supplies is a sensible precaution.
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Sep 22, 2017 02:23
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rawrr posted:If I need 5V for my MCU, some sensors and leds, and 12V to drive a stepper motor (using a driver board like the DRV8825 ones), what would be the best power supply design? Pretty much whatever is easiest. The separate regulation and filtering for your low voltage supplies is enough that it's pretty much never a problem. In typical applications stepper motors pretty much don't have transients the way normal motors do, they present a much more constant load. Unless they're manually spun, then they act as generators. They do act as a pretty heavy load though, so they can easily brown out an insufficient power supplies. The amps going down the motor feed wires is both high current and pulsed, which can easily cause interference on sensitive analog stuff. Separate power supplies won't help here though. Another surprisingly good option is no regulator for the motor supply. Stepper driver chips are current mode switching regulators, and will work just fine off unregulated supplies, provided they aren't too noisy, and have a low enough output impedance.
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Sep 22, 2017 03:22
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Stan Taylor posted:Are there any recommended kits or tutorials for an absolute loving total beginner? I've decided I want to get a soldering iron and maybe a dremel tool and gently caress around with weird robot poo poo alongside software stuff on a raspberry pi. I was looking into beginner arduino kits but might be go for one of those all in one kits that comes preprogrammed and you just have to screw it together and solder a few bits. The toy robot kits start out pretty cheap but the parts costs goes up fast if you want something bigger and stronger. rawrr posted:If I need 5V for my MCU, some sensors and leds, and 12V to drive a stepper motor (using a driver board like the DRV8825 ones), what would be the best power supply design? ... And a DC-buck will lose at least 2 volts, so you want a power supply at least 2 volts more than 5 volts. You can get wall warts and other power supplies in 9v outputs but the 12v ones are much more common and usually cheaper besides. I would get a 12v power supply for the MCU and a DC-buck to convert the 12 volts down to 7 volts, and then connect the 7 volts to the MCU. For BIG motors (nema 23 and 34) I prefer to have the motors on a separate power supply than the MCU, but the drivers you mention are dinky. For one nema-17 motor, I would probably just get a 5-amp 12-volt power supply and run everything off that. Put a fuse on the power supply cord and fuse it aggressively if you want to leave this thing plugged in all the time, or running all the time. The China power supplies USUALLY work just like they're supposed to, but they are very inexpensive. They are not bulletproof and if they are used hard now and then they do have meltdowns. A "good" (fail-safe) power supply will cost ~10X what the China ones do, for the same wattage.
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Sep 22, 2017 13:26
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Stan Taylor posted:Are there any recommended kits or tutorials for an absolute loving total beginner? I've decided I want to get a soldering iron and maybe a dremel tool and gently caress around with weird robot poo poo alongside software stuff on a raspberry pi. I was looking into beginner arduino kits but might be go for one of those all in one kits that comes preprogrammed and you just have to screw it together and solder a few bits. Frankly one of the best ways to get into it is to start by finding a project that really interests you, and then learn as you try to do that. You can certainly get an arduino starter kit or whatever just to play around with (and it is a good way to get a breadboard and a bunch of jumper wires and some little doodads) but without any real direction or drive you kinda just do the basic projects, go "eh that's neat I guess" and then move on. For me, my first project was a geiger counter kit. It just involved putting components on the board and soldering them, but it was really fun to figure out what was doing what, etc.
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Sep 22, 2017 14:30
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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. Someone recommended one of those useless box kits to practice soldering on and that seems like a good idea so that i can quickly have a goofy toy i made. I'm not really sure what kind of stuff is commonly done or possible with these things though.
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Sep 22, 2017 16:34
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