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Chalupa Joe posted:Always on subscription only pricing is the main thing people are upset about, the standard licence is limited to 2 layers (it was 4), and routable area for the free version has been halved.  Why would anyone "upgrade" then? Why not run the previous version forever?Every time I've updated EAGLE, all I've seen is cosmetic changes to the UI...what substantive work are they even doing to it anymore?
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Jan 24, 2017 22:37
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From my limited experience in the last month or two, AutoCAD looks and feels and even has a similar business model to Adobe Acrobat the more I learn about it. Good lord.
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Jan 25, 2017 00:13
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I'll throw my hat in for KiCAD, in case anyone's on the fence. I don't have adequate experience with other PCB CAD software to warrant a comparison, but I've been quite happy with KiCAD caveat: If you're running in on Linux, the installation process is a bit of a pain in the rear end, but then it's pretty smooth afterward. I was actually able to cobble together some python code to edit the PCB files because they're plain text and now I can lay out LEDs, resistors, or other components that go into arrays using a spreadsheet program.  Speaking of board design, I've finally run into an issue with one of my boards I designed for my research where the answer isn't immediately apparent to me. I'm running three NXP PCA9685 LED controllers together on a board. Each chip is sinking up to 20mA on each of 16 pins (so 320mA, which is below the rated max of 400mA). I have a more than adequate PS (~8A max), and I have a 0.1uF ceramic cap between each chip's power and ground pins with reasonable trace management. My prescaler is set so that the PWM frequency should be 1526Hz, but I get flicker at visible frequencies whenever the PWM value is above a certain threshold (but not when everything's configured for full brightness, which is constant-on, or when I'm below a certain value). I expected that there might be some flicker when the PWM value was being changed, but I obviously don't have the correct decoupling solution and/or need a local bypass capacitor beyond the 10uF electrolytic cap I have near the PS connection. Any suggestions/best practices for revising the board?
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Jan 25, 2017 02:00
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Have an oscilloscope?
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Jan 25, 2017 03:29
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ante posted:Have an oscilloscope? I assume there's one floating around my lab somewhere. What should I be looking for?
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Jan 25, 2017 04:40
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poeticoddity posted:I assume there's one floating around my lab somewhere. What should I be looking for? It's like a TV with really complicated controls 
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Jan 25, 2017 14:31
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ate all the Oreos posted:It's like a TV with really complicated controls -_- I have used an oscilloscope before. What should I be looking for in the circuit's behavior?
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Jan 25, 2017 16:34
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I'm lost trying to find the manufacturer or part number of this cable and any mating connector for it. Have any of you guys seen this one before that can identify it?  
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Jan 25, 2017 18:23
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UberVexer posted:I'm lost trying to find the manufacturer or part number of this cable and any mating connector for it. Looks sorta like some kind of aviation connector but those usually have threads... (for example:  )What's it go to?
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Jan 25, 2017 19:00
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ate all the Oreos posted:Looks sorta like some kind of aviation connector but those usually have threads... It goes to a Nikon microscope nosepiece. I was originally thinking that it would be a Hirose connector, but it says made in China, and Hirose has nothing that matches this part.
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Jan 25, 2017 19:27
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poeticoddity posted:I'll throw my hat in for KiCAD, in case anyone's on the fence. I don't have adequate experience with other PCB CAD software to warrant a comparison, but I've been quite happy with KiCAD caveat: If you're running in on Linux, the installation process is a bit of a pain in the rear end, but then it's pretty smooth afterward. I was actually able to cobble together some python code to edit the PCB files because they're plain text and now I can lay out LEDs, resistors, or other components that go into arrays using a spreadsheet program. Have you tried setting different start/stop times for the different channels? Switching all those channels in at the same time could cause some weirdness. Edge case could be that you're seeing an interaction between the devices due to the clocks not being synchronized + a marginal power supply.
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Jan 25, 2017 19:31
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poeticoddity posted:-_- Anything that's not a square wave at the requested frequency. I'd run the duty cycle up and down slowly while looking at the waveform. It should look like this:  Perhaps the flicker is at 60Hz perhaps (AC frequency)?
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Jan 26, 2017 06:04
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poeticoddity posted:-_- Yeah, pretty much like the above. Tap into the signals and test your assumptions about what you think is supposed to be on the output.
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Jan 26, 2017 07:15
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I found this guy's master's thesis randomly googling around and started reading it and I'm 99% sure one of the circuit diagrams is completely wrong but I wanted to confirm I'm not just crazy. It's a programmable load circuit, thesis is here: http://udspace.udel.edu/bitstream/handle/19716/17371/2015_WangYingbo_MS.pdf?sequence=1 circuit:  I'm pretty sure the inverting input of the op-amp should be connected above the resistor, right? Because otherwise it's just referenced to ground... e: Nevermind I didn't catch that those two wires aren't actually joined there, they're just crossing Shame Boy fucked around with this message at 19:47 on Jan 26, 2017 |
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Jan 26, 2017 17:44
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I need help understanding audio numbers. I have a prop - a gun - that I want to have play a sound effect that I have in .wav format. I will be putting an Arduino inside it, an Adafruit Mini Sound Board and also one of Adafruit's 2.5W mono audio amplifiers. This is all running off a 9v battery, regulated through the arduino down to 5v output for the Sound Board and Amp. I have plenty of room inside this gun for a big-ish speaker. Like 35mm diameter round, max. Volume is my priority, as I want the noise this makes to be as loud as possible. How do I pick an appropriate speaker for all this? I don't properly understand Wattage and impedance to the extent that I know how to make an informed decision. Is something like this going to be appropriate to run on the circuit I'm building? Are there better options? Harvey Baldman fucked around with this message at 23:11 on Jan 26, 2017 |
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Jan 26, 2017 23:04
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ate all the Oreos posted:I found this guy's master's thesis randomly googling around and started reading it and I'm 99% sure one of the circuit diagrams is completely wrong but I wanted to confirm I'm not just crazy. It's a programmable load circuit, thesis is here: This is a great example of a poor circuit diagram, those wires didn't need to cross. The author should've just brought that connection lower Harvey Baldman posted:I need help understanding audio numbers. Your amplifier decides the noise more than your speaker does (mostly). Use a 4 ohm (or higher) speaker as that is what your chosen amp says it can handle. It's way more complicated than this and maybe someone will effort post about it but yeah just stick the biggest 4 ohm speaker you can fit in there and that should do the trick.
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Jan 27, 2017 01:29
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The amp will drive that speaker fine. It would be best if you have the speaker open to the air on one side and enclosed on the other. For this the size of the enclosure won't be too critical. For 35mm it wouldn't need to be very big at all.
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Jan 27, 2017 04:49
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ate all the Oreos posted:I found this guy's master's thesis randomly googling around and started reading it and I'm 99% sure one of the circuit diagrams is completely wrong but I wanted to confirm I'm not just crazy. It's a programmable load circuit, thesis is here: Umm that doesn't change the fact that there is no feedback. So it's wrong.
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Jan 27, 2017 05:23
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asdf32 posted:Umm that doesn't change the fact that there is no feedback. So it's wrong. Yeah I played with it in ltspice because I was still *pretty* sure that the op-amp is supposed to be measuring across the resistor because otherwise the resistor is pointless and figured out the right circuit from fiddling
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Jan 27, 2017 06:08
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drat if that's what counts as a Master's thesis then what am I even worrying about. edit: The schematic immediately following the incorrect one seems to have the correct feedback, and it is as you suspected it should be
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Jan 27, 2017 06:51
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BattleMaster posted:drat if that's what counts as a Master's thesis then what am I even worrying about. I'm not sure if this is the final copy or if he passed or anything, it was literally just the first or second google result and i'm like "oh a thesis probably has a lot of documentation and sourcing so it's a good place to lift design ideas from!" but now I'm having second thoughts  And yeah I didn't even notice that second diagram was there until after I figured it out on my own because I was so perplexed and fixated on it, oh well
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Jan 27, 2017 07:04
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Okay so I'm still sort of confused on how diode drop works in a circuit - specifically, is a diode dropping 0.6V with 1A passing through it going to dissipate 0.6W as heat, or is the voltage just, uh, disappearing using some kind of quantum semiconductor hole magic?
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Jan 27, 2017 17:33
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ate all the Oreos posted:Okay so I'm still sort of confused on how diode drop works in a circuit - specifically, is a diode dropping 0.6V with 1A passing through it going to dissipate 0.6W as heat, or is the voltage just, uh, disappearing using some kind of quantum semiconductor hole magic? Yes. .6 watts will be dissipated as heat. If it's a led some of that power would go to light.
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Jan 27, 2017 17:51
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Stabby McDamage posted:Anything that's not a square wave at the requested frequency. I'd run the duty cycle up and down slowly while looking at the waveform. It should look like this: If it's a relatively good scope it might have an FFT function which would make it pretty easy to see.
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Jan 27, 2017 18:27
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Aurium posted:Yes. .6 watts will be dissipated as heat. Ok cool, that's how I was 95% sure it worked but then I thought "but it's not a resistor since it doesn't obey ohm's law at all so my assumptions on power dissipation might not be correct either..." and got all confused. Thanks!
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Jan 27, 2017 18:39
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So I came across a nice little stepper motor from the air-pump for one of those "Sleep Number" beds that the matress was too old and grungy to replace or keep, and I'm curious how to determine how much current it might potentially output if I were to hook it up and give it a good spin.. And since I don't have a setup to easily wind it and measure it, I assume there is some math I ought to be using to figure this out first..? The only info on the motor is "G.S. Electric (General Service Electric?), 120V 60Hz." It's got a part number I can't find on google (which isn't a surprise because the mfr date on the motor is 1989) and I know the entire air-pump unit is 2.5W so I'm assuming I ought to be able to get a decent amount of current since it was sucking like 300W/hr, and I'm pretty sure it's burly enough (I mean it could easily inflate a king-size mattress with two adults on top of it for many many years and still run) to hook up to something and spin it up, maybe a little wind turbine or just a winch or pedal right now.. Enough to experiment with. Anyone care to tell me how stupid and wrong I am?
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Jan 28, 2017 00:30
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coyo7e posted:So I came across a nice little stepper motor from the air-pump for one of those "Sleep Number" beds that the matress was too old and grungy to replace or keep, and I'm curious how to determine how much current it might potentially output if I were to hook it up and give it a good spin.. And since I don't have a setup to easily wind it and measure it, I assume there is some math I ought to be using to figure this out first..? Well for one it's not a stepper motor if it's 120V AC, where'd you get the idea it was one?
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Jan 28, 2017 00:33
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Why would an air pump need a stepper motor anyway? I can't think of any reason you'd need to set the angle of the compressor blades.
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Jan 28, 2017 00:42
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ate all the Oreos posted:Ok cool, that's how I was 95% sure it worked but then I thought "but it's not a resistor since it doesn't obey ohm's law at all so my assumptions on power dissipation might not be correct either..." and got all confused. Thanks! Can't beat the laws of physics. Note that diodes stretch their current ratings a bit (but not so far that they're useless) so you might find, say, a 1A diode in an SOT-23 (usually good for 0.2w or so max) pack and wonder how it can handle ~0.5W and the answer is that it can't, or just barely can but probably shouldn't.
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Jan 28, 2017 01:05
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ate all the Oreos posted:Well for one it's not a stepper motor if it's 120V AC, where'd you get the idea it was one? 
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Jan 28, 2017 01:25
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I think that almost all electronically controlled brushless motors are variations on a step motor but a step motor is called that because the intent is to control it to stop at specific steps. E: AC Motors can also work on similar principles by using the alternating current to energize the windings in sequence. I could be completely wrong I'm not a motor expert I did implement a motor controller for a gimbal in an fpga once so all I know is from researching that. Murgos fucked around with this message at 02:48 on Jan 28, 2017 |
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Jan 28, 2017 02:44
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Murgos posted:I think that almost all electronically controlled brushless motors are variations on a step motor but a step motor is called that because the intent is to control it to stop at specific steps. DC motors sure, but this sounds like an AC motor unless there's some hidden circuitry we don't know about. It sounds like the only control would just be off or on, so it doesn't really need more than that. e: didn't get your edit 
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Jan 28, 2017 02:48
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coyo7e posted:oops, my bad. I thought it was a stepper because it's got a whole array of little guys that looked like magnets surrounding the shaft. That's the commutator, it's made of copper, not magnets. It's a brushed motor, those graphite blocks on springs are the brushes. Stepper motors are brushless and way different from that.
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Jan 28, 2017 03:00
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coyo7e posted:oops, my bad. I thought it was a stepper because it's got a whole array of little guys that looked like magnets surrounding the shaft. https://en.wikipedia.org/wiki/Universal_motor Universal, because you see them everywhere. Edit: If you can't use the motor for anything, take it apart and save the windings if nothing else. Enameled magnet wire is fun to play with, especially when it's thick enough to handle some decent current. Effective-Disorder fucked around with this message at 09:39 on Jan 28, 2017 |
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Jan 28, 2017 09:35
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So assuming I wanted to build a 1000base-X (Gigabit ethernet over fiber) media converter or switch (e.g. 2xfiber+some copper), are there any ICs that are suitable or would I be better off using an FPGA or CPLD? I know I can buy ready made converters and switches from e.g. TP-Link, but I'm curious since I couldn't really find anything designed for the job.
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Jan 28, 2017 12:24
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longview posted:So assuming I wanted to build a 1000base-X (Gigabit ethernet over fiber) media converter or switch (e.g. 2xfiber+some copper), are there any ICs that are suitable or would I be better off using an FPGA or CPLD? Buy something with a few sfp ports and plug and play
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Jan 28, 2017 15:10
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I have a little, old 9" CRT TV that I use to aim CCTV cameras and as a monitor for configuring our older DVRs. The problem with the dang thing is that you need the remote to switch between the tuner and the composite in port, the TV/AUX button, and sometimes if I haven't used it in awhile it defaults back to the tuner. Obviously this is a pain in the rear end because I have to dig out the remote and make sure it has batteries with some juice left in them each time to press one stupid button. Would it be possible for me to add that button to the case somehow so I can lose the stupid remote? Yes, I know how to safely discharge a CRT before working around them.
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Feb 1, 2017 21:24
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Edit: Literally the moment after I post my question post relating to DHT11, I solved it. I'm an idiot!
Fat Turkey fucked around with this message at 01:02 on Feb 2, 2017 |
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Feb 2, 2017 00:58
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kid sinister posted:I have a little, old 9" CRT TV that I use to aim CCTV cameras and as a monitor for configuring our older DVRs. The problem with the dang thing is that you need the remote to switch between the tuner and the composite in port, the TV/AUX button, and sometimes if I haven't used it in awhile it defaults back to the tuner. Obviously this is a pain in the rear end because I have to dig out the remote and make sure it has batteries with some juice left in them each time to press one stupid button. Would it be possible for me to add that button to the case somehow so I can lose the stupid remote? Yes, I know how to safely discharge a CRT before working around them. Do you ever want to use the tuner again? Without knowing the internals, it's easy to imagine the signal path from IR to input switcher being pretty opaque, but hard wiring the input to AUX might be pretty attainable. What you're asking is probably doable, but possibly a lot more involved.
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Feb 2, 2017 01:10
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kid sinister posted:I have a little, old 9" CRT TV that I use to aim CCTV cameras and as a monitor for configuring our older DVRs. The problem with the dang thing is that you need the remote to switch between the tuner and the composite in port, the TV/AUX button, and sometimes if I haven't used it in awhile it defaults back to the tuner. Obviously this is a pain in the rear end because I have to dig out the remote and make sure it has batteries with some juice left in them each time to press one stupid button. Would it be possible for me to add that button to the case somehow so I can lose the stupid remote? Yes, I know how to safely discharge a CRT before working around them. It'll be sending some sort of digital signal via IR, which then controls a bunch of stuff on the TV, probably. It's not like breaking out a single wire to a button. Hardwire the remote to power and tape it to the CRT? Arduino with an IR LED plugged into it sending the signal on button press? Arduino hooked into the signal path of input IR, bypassing the light stuff entirely. Those are probably your options.
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Feb 2, 2017 03:42
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