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mtwieg posted:Can anyone tell me where I can get lead free solder paste? Like a few hundred milliliters of the stuff. Right on. Here's a place I bought LEDs from: http://www.superbrightleds.com/ LEDs of every color. Be sure to check the datasheet - not every LED has a forward voltage drop of 1.4V, and not all of them have a 10mA draw. This is particularly true of much larger, more powerful LEDs (aka the "1 watt" or "Luxeon" LEDS). For instance, the RL5-WW7035 (warm white LED) on SBL, it has a 3.2V drop and a continuous forward current rating of 30mA. If you do get those large LEDs (1 Watt and higher) be sure to attach them to a heatsink - if you don't they can burn out. SPICE and Circuit Simulation Find the student version of PSPice. I think I'll make a little tutorial on simulating circuits in PSpice (that doesn't suck). Three-Phase fucked around with this message at 02:19 on Jan 13, 2008 |
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Jan 13, 2008 02:04
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Cyril Sneer posted:*sigh* From what I've seen, digital and RF go hand in hand. Especially when you're talking about things like CE testing for noise immunity. I work with bigger stuff, where you need to make sure different cables are separated. (Like not running an unshielded twisted-pair carrying a 4-20mA signal right next to a massive 500kmcm cable that can cary 600 amps. - That's a class-4 versus class-1 if I remember correctly, and without shielding they would need to be a meter or so apart.)
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Jan 13, 2008 14:44
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mtwieg posted:
I love their Capacitor Comparison Chart. "Ghastly" temperature stability.
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Jan 16, 2008 01:03
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Horowitz and Hill
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Since we're all talking about LEDs, I'll have to show you the circuit and implementation I'm working on. I'm transforming a Petzl zoom headlamp to operate three superbright LEDs off of two "C" cell batteries. To do this I've constructed a regulated boost converter. I'm going to work on the protoboard today.
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Apr 6, 2008 13:56
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nouia posted:Finished the triple CREE headlight. The hardest part was just making all those connections inside the aluminum housing. Wow, very bitchen' headlight. Powerful. Those LEDs have come very far - I remember getting some of the 1-watt Luxeon stars when they were pretty new and showing them to some professors who were amazed by the light output. - I must also comment that I've looked through the little "articles" and tutorials here - they are very well done and a lot of thought has gone into them. Explaining tricky concepts in understandable terms is a valuable skill. Three-Phase fucked around with this message at 04:58 on Apr 12, 2008 |
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Apr 12, 2008 04:44
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I just want to make sure I'm correct here, as far as the best/worst ways to turn variable X voltage into steady Y voltage (DC): WORST (Efficiency wise) -Resistor network -Zener diode -Linear regulator -Switching regulator BEST (Efficiency wise) I was talking to someone doing some military applications and they had to use linear regulators because the switching regulator risked making too much noise. Oh, and here is the Petzl Zoom regulated LED retrofit I cooked up:    It runs off of AAs or C batteries. The current pull at 3V is approximately 100mA. It has a boost converter that switches the input voltage up to around 9 volts, which powers the two sets of three LEDs (and a small resistor.) A current source would have been a better approach, but with precise control of the output voltage I could use a very small current limiting resistor to waste little power. Also with the regulation it will maintain the same brightness for awhile then drop off as the battery dies. If you want something pretty, this isn't for you. But it's solid and functional. Three-Phase fucked around with this message at 01:24 on Apr 15, 2008 |
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Apr 15, 2008 01:16
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mtwieg posted:Now for something different: Switching supply theory Just one note - you really want a Schottky diode for this sort of supply. Normal diodes have a voltage drop of around 0.7, while a Schottky diode has a much lower voltage drop. Still, excellent writeup.
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Apr 23, 2008 04:07
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Ok, I need some help from the PIC pros here. I got an ICD2 programmer from my pop. Installed it on my computer, it seemed to run OK, then it went to hell quick. This is an image of the offending device.  In my opinion, this device is a complete hunk of poo poo. There's a ton of weird driver voodoo-hoodoo with it, like these pre-install and cleaning utilities. Plus it's finnicky about power connections and soforth. My dad had issues with it as well on a separate computer, so I'm doubting it's a solo issue. Now this is what I want to do - program PIC chips on my computer. I have a 232 port and a USB port. I liked Microchip's IDE, and the PicKit 2 prototype board. I need something like this, without needing that shitpuck programmer. UPDATE! Doing a careful removal/reinstall appeared to get the thing working... for now. If it doesn't "break" again I'll improve this device's review from a "complete hunk of poo poo" to "crappy". Three-Phase fucked around with this message at 16:53 on May 12, 2008 |
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May 12, 2008 16:37
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babyeatingpsychopath posted:I have a PICkit2 programmer and "PICkit 2 Low Pin Count Demo" demo board that work flawlessly. I got the PICDEM board, I like that since you can program a wider variety of PIC chips. I'm catching onto the nuances of the PIC pretty well. I've made a little LED-stroby program. Had some difficulty with an A/D input thing - I think I was moving too fast and need to cover the initial stuff a bit better. Having worked with an 8051, this is pretty much the same, with some different nuances and commands.
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May 13, 2008 04:12
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Delta-Wye posted:or it was really conductive to learning. So what's he currently working on? Heck with this piddly "milliamp" crap too - I'm thinking about doing a useful primer on power electronics in this thread. (120V stuff, not the good stuff in the kV/kA range.) Three-Phase fucked around with this message at 11:23 on Jun 17, 2008 |
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Jun 17, 2008 11:18
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Jonny 290 posted:Small signal stuff is neat but I think that working with high current and/or voltage is an interesting and worthy challenge. It's one of the main reasons that I am investigating converting a crotch rocket to electric - I want to build the motor controller myself. Something about PWM'ing 80 amps at 48 volts makes me RRRRRR. It'd do-able. I'm used to using large SCR "pucks" for switching AC. Except we're talking about maybe 1000 or so amps. You can get different AC signals with lower RMS voltages, as well as creating DC with variable voltage levels depending on how you hook up the SCRs. If you wanted to be really fancy-schmancy, you could hook up some sort of speed transducer, have a feedback loop, and have cruise control.
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Jun 19, 2008 22:41
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Bush is a QT posted:Using his knowledge of transformers he went to the dump and made a transformer out of scrap. He went door to door trying to sell it until he finally sold one. Then he made another and sold it. And so on and so fourth. The really cool part is that he constructed the transformer in an ISO-9001 certified dump. Mr. Powers posted:Why would someone buy a transformer from a door to door salesman? You know, I've been meaning to get a transformer for my apartment. Except for some NEC issues and the fact that The Illuminating Company outright refused to run a 4160/2400V drop to my apartment. Three-Phase fucked around with this message at 02:56 on Jun 25, 2008 |
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Jun 25, 2008 02:53
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ChaoticSeven posted:Can anyone tell me which would be more accurate at maintaining a constant temperature in an incubator environment (chicken/quail eggs) while dealing with ambient temperature swings? Trying to decide between using a proportional thermostat or putting together a controller using a PID, RTD sensor and a solid state relay to control the heat source. Also it should be known I know jack poo poo about electronics and I'm stumbling along trying to figure out this poo poo with Google and leaps of faith. http://auberins.com/index.php?main_page=product_info&products_id=3 That might be a nice little device - the only thing is I'm concerned about the potential for loss if you make a homebuilt PID controller. The cool thing about this one is that it also has alarm functionality in case the temperature starts to get dangerously low. Wire a thermocouple into it - it'll use this to measure the temperature. Then you can buy a little SSR and use that to control a heat source.
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Feb 24, 2009 02:22
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Boy, you guys ought'a have seen what we were doing - 200kVA UPS system, some really serious silicon. (IGBT rectifier/inverter). This thread's cute with all your little milliamps... 
Three-Phase fucked around with this message at 14:52 on Mar 27, 2011 |
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Mar 27, 2011 14:01
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Skinny Bins posted:Hey ElectroGoons, Skinny, instead of using discrete counters, have you considered buying a microprocessor like the PicAxe microcontroller or a Basic Stamp and doing the counting and stuff in software? Having a single device handle the input, output, and logic would probably be the simplest solution. Are you familiar with Basic or C programming? If so, with a little studying you could probably program one of these. If you wanted to do more fancy stuff, you might need a multiplexer chip or some other add-ons. ANIME AKBAR posted:In the next month we're going to be finishing off a couple interleaved 25KW PFCs. I don't think I ever want to work at a higher power level. It becomes more of a mechanical problem (heatsink design/laminated bus machining/cabling harnesses) than an electrical problem (more silicon/ferrite/copper). It just takes all the fun out of it. I remember getting SCR modules from that same company, I think they were around 3000A. As far as bigger stuff goes - ABB Megadrive. Up to around 100,000HP at medium voltage, higher on request. Water-cooled for larger systems. They have a Megadrive at one of the NASA facilities that's a 135,000 HP synchronous motor. I've seen ABB's "smaller" drives that are in the 15,000-HP area at 13kVAC. Three-Phase fucked around with this message at 23:40 on Mar 27, 2011 |
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Mar 27, 2011 19:50
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ANIME AKBAR posted:See, the only thing I could see worthwhile about those kind of power levels would be if you started using old school rectifiers, like ignitrons and thyratrons and other cool poo poo. An arc rectifier the size of a schoolbus. Probably would look like something out of a video game you'd have to blow up at the end to win.
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Mar 27, 2011 22:01
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Ok, got a basic project idea, a little unorthodox. I want to make a sort-of homemade security monitor. I'm thinking a microcontroller with the following inputs: 1. Temperature 2. Motion detector (movement in past 24 hours) 3. Light level Now there are two ways to get that data to me: 1. Ethernet connection to my router, have the device somehow send e-mail every X hours or when something significantly changes 2. Have a RS-232 connection from the microcontroller to a modem As far as the modem goes, I'd just make a long-distance call to my apartment, and have the microcontroller initialize the modem on boot (send a command that specifies 9600 baud, parity, answer on the first ring) and just wait for me to phone home to it. After initializing, the microcontroller would just send text data to the RS-232 port every 10 seconds or so. Would either of these approaches work?
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Apr 17, 2011 15:09
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Sorta' wanted it to be standalone, I don't like leaving my PC on for extended periods when I'm away.
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Apr 17, 2011 22:04
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Master Stur posted:And here's the final product! I jumped in my chair a little. You might want to consider a breadboard. Or submitting it to a museum as a modern art project.
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Apr 30, 2011 03:51
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Uhm that looks really bad! This is actually the 4th attempt at soldering this sucker so that should speak for how talented we are. But how does it perform?
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 ELECTRICAL PROBLEMI've got this friend Rocky at my apartment complex. He's this WWII vet with an old television. It's got a HD/LD converter connected with a wallwort, and a pair of rabbit ears running into the converter. Today, when I touched the rabbit ears to try and adjust them, I received a shock. It was the "finger touching a hot pan" sort of shock, not one of these "oh poo poo I'm going to die call 911 turn it off turn it off turn it off" kind of shocks. However I had my Fluke volt-alert, and when I held it next to the whole antenna arrangement it sang from about 1/4th of an inch or closer. It looks like the shield is either energized or is holding a charge. I'm still wondering what the hell caused it. I did notice that the set is really old and has a two-prong plug. Could the set have the frame grounded to one of the prongs? I've heard of older appliances that have done this, and supposedly those things can be dangerous. I'm wondering if the TV has some kind of ground connection or is trying to ground via the antenna? I'm typically much better at solving electrical problems on much larger equipment - I usually don't deal with little appliances and the like.
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Jul 14, 2012 00:47
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babyeatingpsychopath posted:Those voltalert things go CRAZY for HF. On some 2.4V/200mA LED drivers at 30kHz, mine will beep from a few inches away. I know 30kHz isn't HF, but the detector is usually an inductor tuned for 60Hz, so that's pretty high frequency, considering. True, very true. 4160V at 60hz also makes it ring from a few inches away. Not sure about 13800V. Not going to try and find out. 
Three-Phase fucked around with this message at 01:24 on Jul 31, 2012 |
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Jul 31, 2012 01:21
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Heat Question! This is more of a communications/general electronics thing: I have a Motorola SB6180 cable modem. It works great, but I've noticed it gets pretty hot at the top of the case. The metal back section where the plugs are are lukewarm, the cables are cool, the wall-wart is warm (but not excessively so), but there's a considerable amount of heat coming out of the cable modem. It is NOT hot enough so that it cannot be uncomfortably held. But it's a lot more heat than my DSL modem (the piece of poo poo that it was) put out. I'm not sure yet if the heat level is constant or depends on how much data is being received and transmitted. I've read reports of people with Motorola Surfboards running the gambit from "cool" to "very hot". There are no obvious signs of a malfunction, like the modem locking up, connection problems, or anything like that. No melting plastic or magic smoke smells. I was talking to my dad, and he thought the DSP in the modem might be generating the heat. I've seen elsewhere mentioned that the cable tuner circuit can run hot. Any ideas as to what specifically will be creating all the heat in the modem? There is a reasonably-sized heatsink near the top, so I've deduced that's where the heat is coming from. It's about one square inch, and the fins are arranged so there should be a nice chimney-effect as far as cooling goes when the unit is placed vertically.
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Apr 16, 2013 00:36
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longview posted:DSP, line drivers for the cable output (basically a medium size radio transmitter), internal power supply. Really the only way to tell is to pop it open and try feeling around! Is there a reason you want to know or is it just curiosity? It just seems to run so much warmer than all my other electronics. I talked to some other people and my understanding is that there are a lot of newer devices that are in smaller, higher-power packages, so devices potentially running very hot are not that unusual. (I know my WD TV HD gets fairly hot as well.)
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May 25, 2013 13:24
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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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