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It pains me to see how much of a moron you actually are. Sorry, but anyone who figures out what resistances to use by mixing and matching until they hit the right one has no right correcting anything anyone says. But ok, let's go. SkunkDuster posted:Here we are talking about using a 12V supply to light up LEDs (first mention of 12V). SkunkDuster posted:Here is a 1/4W (250mW) resistor failing miserably in Scholzie's scenario (second mention of 12V): Ahem, SkunkDuster posted:You're right that at 12V and below in the 20-25mA range that a .25W resistor should be fine for whatever you are doing. When I mentioned using a higher wattage resistor or multiple lower wattage resistors, I was getting another project where I had to do that mixed up with some of the LED stuff I've worked on. I guess it's my fault that I replied to something you admittedly hosed up on. Let's flame scholzie! My original point still stands, considering most LEDs (go ahead and try to prove me wrong) run around 25mA at ~3V. I've personally never seen any normal LED running at 50mA within spec. This is clearly a special case. I've wired up hundreds of LEDs in my lifetime and have never needed higher than a 1/4W resistor. Since you said only care about hobbyists wiring blooooo LEDs into their PS2 controllers, you should be in agreement that 1/4W will be fine for everything you'll ever need. Sorry I didn't add a catchall clause for every situation using every voltage and every power supply ever. Ever. Yes, if you run a 3V LED on a 12V supply, dropping 9V across a resistor at 50mA, you will need a half watt resistor. (Btw, instead of running the circuit for 5 minutes and feeling it with my hands, which really can't tell if a resistor is too hot or not, I could do a 5 second calculation P = 9V*50mA = 450mW and know right away) SkunkDuster posted:
SkunkDuster posted:And some more poo poo that is dead wrong: Most people don't sit in front of their DC LED circuit and loving crank a variable resistor to change current. Once you pick a voltage drop and stick to it, the math falls in place. If you're going to sit here and try to argue semantics then you've got way too much time on your hands. We (real engineers, not pretend ones like you) model diodes as ohmic devices all the time and no one has died from it. Incidentally, you didn't supply plots, just a bunch of numbers. This is a true diode IV characteristic: See that nice straight line after the curvy bit? That's I/V. That slope is equal to 1/R (= S [edit: I means S as in Siemens, not S as in the graph's "S=10-4"). If you set your voltage well past the threshold, you do NOT have to worry about changing resistance. SkunkDuster posted:
SkunkDuster posted:I'd have to consult Schrödinger on that one. SkunkDuster posted:
SkunkDuster posted:Your math and formulas are dead on correct, but some of the stuff you have posted in this thread ranges from unclear to completely wrong. This is a great thread and I agree that SkunkDuster posted:so please take a couple minutes to look over your replies to make sure you are talking about the same thing the person you are replying to is (12V vs 5V) and your facts are correct (75mA PEAK voltage). SkunkDuster posted:I'm also looking forward to this: Can we move on now? Christ Almighty. scholzie fucked around with this message at 09:26 on Jan 11, 2008 |
# ? Jan 10, 2008 00:46 |
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# ? May 21, 2024 18:01 |
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Chalupa Joe posted:In my experience, 99.99% of the time where the Auto-router is used, you end up with a board that won't work properly (i.e. susceptible to EMI), as they're all variations on "Drunkard dragging a wet bit of string around". This is very, very true. Especially if you have switching power supplies, high speed traces or sensitive analog areas, your layout becomes as important as the actual schematic. I know some people might be put off at the complexity of doing a hand layout using free tools, but realize that even expensive software packages will probably still suck enough to make you do it by hand as well (I'm looking at you Mentor Graphics).
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# ? Jan 10, 2008 00:48 |
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Hillridge posted:A good thing to do to keep your iron tips fresh and shiny is to "tin" them before turning the iron off. Basically cover the whole tip with a big glob of solder and let it cool on there. When you need to use the iron again, just let it heat up and wipe off the solder on the sponge. quote:By heat gun I actually meant one of these guys: quote:
Well, I definitely need to upgrade something. Desoldering a single part can take me half an hour or more if it's stubborn and has a lot of leads. Thanks for the informative post! Mill Town fucked around with this message at 01:15 on Jan 10, 2008 |
# ? Jan 10, 2008 01:11 |
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Circumcision Hater posted:Well, I definitely need to upgrade something. Desoldering a single part can take me half an hour or more if it's stubborn and has a lot of leads. If you're having problems desoldering standard parts (meaning the cheap throwaway ones), I'd go ahead and solder them in with a bit more lead on the device side next time. That way, if you need to take them out you can just snip the part off (try to save as much as you can so you can use it again down the line). Then you can hold the board with some Helping Hands (see an earlier post), hold the lead with some pliers, and then heat the joint with the iron. The lead will pull right out, and you can then press some desoldering braid on the joint to clean up the excess solder. For more expensive or limited supply parts, you might considering using sockets rather than hardwiring the device in. This is especially useful with ICs and hard to find special order transistors (like new old stock germanium ones from the 60s). This has the added benefit of protecting the more sensitive devices from too much heat when soldering since you can just install them after you're finished applying heat. Lastly, if you find yourself doing a lot of prototyping, you'd be smart to pick up a Wire Wrap Gun. These will allow you to make some very strong connections with a perfboard, without making them permanent. You'll be able to fully test the device, then unwrap if necessary to fix anything. Bonus: once you've verified it's all working, you can solder right over the wire wrap if you don't care about it being messy. Now you won't lose anything in the translation from wrap to solder.
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# ? Jan 10, 2008 01:35 |
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Ok, tomorrow's moving day and unfortunately Time Warner is playing games with me and I might be without internet for a bit. Oh joy. I'll do updates when I return.
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# ? Jan 10, 2008 04:24 |
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Does this make me a bad person?
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# ? Jan 10, 2008 05:09 |
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No Jailbrekr, these make you a great person. poo poo, we could have a mspaint your favorite electronics principles thread in GBS and not get stuff as good as this.
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# ? Jan 10, 2008 05:40 |
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franc0ph0bic posted:Im just gonna throw this in - if anybody out there plays any for of amplified instrument (ie. electric guitar/bass, electric violin...) making simple circuits to modify the sound is very popular. I have made many different guitar effects, including distortions, delays, and modulation effects. There are many good beginner projects that are also very useful, and its a great way to learn electronics. This is the main reason why I'm interested. I've found numerous sites online that have board layouts for different effects but I have yet to find a source for the reason behind placement of resistors and capacitors. Obviously designing my own pedal would be a project for the extreme future but I'd like to at least know the theory behind the design and how each part affects the sound. Do you have tips or know of any resources to how they shape sound? Like how would you go about designing a delay from scratch?
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# ? Jan 10, 2008 05:51 |
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spencer for hire posted:This is the main reason why I'm interested. I've found numerous sites online that have board layouts for different effects but I have yet to find a source for the reason behind placement of resistors and capacitors. Obviously designing my own pedal would be a project for the extreme future but I'd like to at least know the theory behind the design and how each part affects the sound. Do you have tips or know of any resources to how they shape sound? Like how would you go about designing a delay from scratch? If you provide me with a schematic I might be able to analyze it over the weekend and do my best to describe it in stages with SPICE simulations and
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# ? Jan 10, 2008 06:50 |
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Jairbrekr posted:Does this make me a bad person? Needs more sex and explanation.
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# ? Jan 10, 2008 06:55 |
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Kahlua Bomb posted:Do you have any good resources for plans/parts/kits? Yes, but only for guitar/bass related stuff. A good place for kits is Build Your Own Clone (http://www.buildyourownclone.com/) which sells a few overpriced kits which are clones of commercial effects. http://runoffgroove.com is a great site for more original schematics, but they do not sell kits. http://www.tonepad.com is another great site like this. The absolute best resource is http://www.diystompboxes.com/ which has the most active and productive effects building forum available.
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# ? Jan 10, 2008 06:58 |
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async1ronous posted:Needs more sex and explanation. Ya, it was a real quick job and I wish I had put more effort like throwing in an xy graph that relates graph usage with faggotry.
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# ? Jan 10, 2008 08:05 |
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You need to write a book and put all these great diagrams in it, Jairbrekr. It could be called ELECTRONICS FOR FAGGOTS: HOLY TAPDANCING CHRIST LOOK AT THESE ELECTRONS.
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# ? Jan 10, 2008 19:39 |
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A lot of companies will give you free samples of parts. I have a bunch of PICs and a MEMS accelerometer at home that I got just by asking. Some sites even have a sample parts form you can fill out. As a hobbyist, you generally only need one-off parts, so it's a great way to keep your costs down, especially for more expensive bits like sensors and MCUs.
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# ? Jan 10, 2008 20:35 |
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Zenaida posted:A lot of companies will give you free samples of parts. I have a bunch of PICs and a MEMS accelerometer at home that I got just by asking. Some sites even have a sample parts form you can fill out. As a hobbyist, you generally only need one-off parts, so it's a great way to keep your costs down, especially for more expensive bits like sensors and MCUs. This is a good point. There are alot of free sample sites lined from this one= http://www.dutchforce.com/~eforum/index.php?showtopic=13348 Follow the rules and you will get alot of free stuff.
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# ? Jan 10, 2008 22:58 |
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Has anyone has an experience with these relatively cheap (~$200US) USB digital storage oscilloscopes? http://www.beigly.com/catalog/hantek-dso2090-oscilloscope-p-96.html I am thinking of getting one off eBay, however I would like to get some feedback from some people before I drop $200 bucks. I would be using this oscilloscope mainly for audio circuitry so the 40MHz bandwidth is more than enough! Thanks
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# ? Jan 10, 2008 23:31 |
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WilfBerT posted:Has anyone has an experience with these relatively cheap (~$200US) USB digital storage oscilloscopes? It can't do an FFT which probably can't be expected from any $200 scope but I really wouldn't buy a scope that couldn't do it. It's really nice to be able to see harmonic content of your output waveform especially in audio circuits.
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# ? Jan 11, 2008 00:25 |
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I love watching engineers engaged in debate
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# ? Jan 11, 2008 04:12 |
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WilfBerT posted:Has anyone has an experience with these relatively cheap (~$200US) USB digital storage oscilloscopes? I hate these things. They tend to be laggy and poorly featured. They work ok if you are just trying to automatically log some waveforms. But for interactive work they are kind of a pain. Really, you would be best served by getting a real scope off of ebay. An analog tek 7000 series mainframe scope can work pretty well. Or just save up 1000$ for a small tek scope. Or hit ebay every day and learn which scope are worthwhile and which are not. Instek can sometimes have cheap equipment as well. I kind of wish there was more of a market, an opensource scope kit would be nice.
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# ? Jan 11, 2008 05:44 |
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ValhallaSmith posted:I hate these things. They tend to be laggy and poorly featured. They work ok if you are just trying to automatically log some waveforms. But for interactive work they are kind of a pain. That is not entirely sure. We have some usb scopes in my labs that have no lag and have a slew of features present in more expensive in only the more expensive Tektronix. Things like FFT are a bit slower than an entire DSP based system like those in a good high end scope but still it functions well enough for basic measurements. Also the ability to dump data directly to excel is oh so nice, although you can do that with some of the newer cheap scopes anyway so it is a moot point. If you have an engineering school near you I recommend you check out their salvage store, whatever the hell they call it, mine had http://www.tek.com/products/oscilloscopes/tds1000_tds2000/index.html these for sale for like $50 a piece or something, of course they probably had the insides gutted about 30 times because of the silly freshman EEs killing them somehow(still not sure how to kill a scope but I've seen it done). Deals can also be had on craigslist pretty regularly if you live in a big city. I just started a class on DSP's and I can honestly say these are by far the most interesting things I have touched upon in any class ever. We are only a week into lecture and have already learned how to implelement relatively complex high order filters really easily. Digital ROCKS!
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# ? Jan 11, 2008 14:57 |
Can anyone tell me where I can get lead free solder paste? Like a few hundred milliliters of the stuff. And REAL MEN drive their LEDs with current sources.
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# ? Jan 12, 2008 11:37 |
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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. digikey.com or mouser.com should be able to hook you up.
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# ? Jan 12, 2008 16:12 |
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Cuw posted:Digital ROCKS! *sigh* ah well, maybe with everyone focusing on digital subjects these days, there'll be more jobs for us RF people.
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# ? Jan 12, 2008 16:23 |
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franc0ph0bic posted:Yes, but only for guitar/bass related stuff. A good place for kits is Build Your Own Clone (http://www.buildyourownclone.com/) which sells a few overpriced kits which are clones of commercial effects. http://runoffgroove.com is a great site for more original schematics, but they do not sell kits. http://www.tonepad.com is another great site like this. The absolute best resource is http://www.diystompboxes.com/ which has the most active and productive effects building forum available. I would like to add these sites too: http://www.commonsound.com/ mostly guitar/bass related but alot of the projects are able self oscillate and can be used with out either and the Tri-Wave Picogenerator is a great noisemaker. http://www.generalguitargadgets.com/ kits, layouts, schematics http://olcircuits.com/ sells kits of RunOffGrooves projects http://www.home-wrecker.com/ a sister site to RunOffGroove focusing on clones http://www.geofex.com/ One of the best sites that explain the theory behind what makes effects "tick" schematics, and project ideas too. http://www.smallbearelec.com/StoreFront.bok electronics supplier dedicated to the parts needed to build effects pedals with carrys some specialized parts that are hard to track down via other sites. I probably have more I need to sort through my bookmarks.
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# ? Jan 12, 2008 20:54 |
slackingest posted:digikey.com or mouser.com should be able to hook you up. Also I dig the new mosfet av.
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# ? Jan 12, 2008 22:40 |
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What do you guys think beginning electronics hobbyists would want in a power supply? I was thinking of offering free schematic and a kit. Is it better to just keep it as cheap as possible (under 10$) or give it some features that drive up the cost? I was thinking of something with a bare minimum of features right now. Also I want to keep the size down so it can fit in an altoids tin. I would ditch any display or controls in favor of a USB pic uC. This keeps costs down since you can get a PIC sample free from microchip. The power supply would be able to do 0-~15v depending on what type of DC wall wart you plug into it. Current limiting, but I think I will forgo remote sense to start with. Not sure how many outputs. Probably just 1. I figure the PIC, Op amps, regulator and transistors can be had for free. You can eat the altoids, so you just need to get a small kit of passive components and some connectors (banana posts, USB, wall wart power). So yea, 0-15v@1A, PC controlled, variable current limit. Think that would be a good hobby power supply? mtwieg posted:That was the first place I checked, but they don't have it (in reasonable quantities, at least). These guys have free 250g paste samples: http://www.smtsolderpaste.com/free_solder_paste.php ValhallaSmith fucked around with this message at 22:44 on Jan 12, 2008 |
# ? Jan 12, 2008 22:41 |
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Thumposaurus posted:I would like to add these sites too: Thanks for posting these! I have been interested in getting back into making electronics stuff, and I think this is exactly what I'd like to make. Tremolo effect stompbox incoming..... Edit: I'm pretty sure but I just want to make sure.... will most of these effect pedals while being designed for a guitar, still sound alright on a bass?
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# ? Jan 12, 2008 23:27 |
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They will be fine for bass, the only change you might want to make is the input/output capacitors. I forget which it is right now but increasing/decreasing them changes the amount of low end frequencies that get through. That is what is great about building them yourself you can tweak and tweak until it sounds perfect to you. The Commonsound Tremolo is a great one and not too difficult.
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# ? Jan 13, 2008 01:22 |
ValhallaSmith posted:These guys have free 250g paste samples: http://www.smtsolderpaste.com/free_solder_paste.php And as for your power supply, you might be best off rolling your own linear regulator. It's fairly simple and there's no need for digital stuff (unless you want a built in meter or something). I can post an example schematic if you want. ANIME AKBAR fucked around with this message at 02:04 on Jan 13, 2008 |
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# ? Jan 13, 2008 02:00 |
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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 |
# ? Jan 13, 2008 02:04 |
Jairbrekr would you be mad if I stole your gimmick and did a a minilesson on transistors? edit: poo poo, you did that already. Maybe I could do some example transistor circuits. ANIME AKBAR fucked around with this message at 02:57 on Jan 13, 2008 |
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# ? Jan 13, 2008 02:46 |
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mtwieg posted:Well poo poo, that looks great, thanks. I've built tons of those. What I'm trying to come up with is something very cheap for the hobbyist. The reason I would go with a pic or avr is because using one of those over USB is cheaper than adding in everything you need for a display, controls and switches. Plus I want to keep these at a very small form factor (altoid form factor). I've been reading up on synthetic instrumentation for a chunk of the day. I might draw something up that heads in that direction. Instead of a power supply you could basically build a DAC. Then if you want a voltage meter you add a ADC voltage module. If you want power factor correction/metering you add a shunt resistor, amp and another adc. Basically a very generic instrument set that performs most of the measurement on the PC. It would be USB 2.0 based so that would kind of limit things at times. USB has crappy latency. But 10$ per module isn't that bad I don't think. Most people don't need sampling in the ghz range. I think just making a 1khz DAC and a 1mhz adc would be a good start.
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# ? Jan 13, 2008 04:26 |
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mtwieg posted:Jairbrekr would you be mad if I stole your gimmick and did a a minilesson on transistors? FYI, it's not Jairbrekr's gimmick. His are pretty good though. There was a whole thread dedicated to explaining things with foul language. I was actually going to post the links that Thumposaurus posted above. They're great resources (especially geofex, if you're actually interested in learning HOW effects work). I used a fuzz face schematic from General Guitar Gadgets with matching germanium transistors purchased from small bear, and it came out pretty good. It has two volume knobs, though, because I messed up my wiring. I keep putting off the debugging because I've been happy with it as it is, but I guess it's probably a good idea to see what's wrong.
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# ? Jan 13, 2008 04:54 |
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Cyril Sneer posted:*sigh* we can work together to create the greatest things ever. The lines between digital and everything else are shrinking so fast that without a strong digital background I can't see how you really won't sink in the industry.
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# ? Jan 13, 2008 06:42 |
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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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*phew* finally back. I'll be working on the OP and cleaning up the drat LED project for ya. Also the reason I said to check the spec sheet in the LED project is that not every LED has the same voltage drop and current draw, esp. not high power LEDs. I could make a current-driven LED next using a BJT...would you enjoy that?
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# ? Jan 13, 2008 23:00 |
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Three-Phase posted: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. It is amazing how diverse the field of EE is. It gets even more diverse when you throw the C in there and do ECE. It really surprises me it hasn't broken down further at this point at most major colleges since there really is no way for anyone to be proficient in all of this stuff by the time they graduate.
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# ? Jan 13, 2008 23:28 |
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Cuw posted:It is amazing how diverse the field of EE is. It gets even more diverse when you throw the C in there and do ECE. It really surprises me it hasn't broken down further at this point at most major colleges since there really is no way for anyone to be proficient in all of this stuff by the time they graduate. I think that's the purpose of having CE and EE separate, but it's not a great seperation if you ask me. Digital stuff is absolutely everywhere and everyone in EE needs at least a little exposure to digital technology at this point. From what I count though, here are the EE 'disciplines': -Power Systems -Computer Systems -RF/Analog Systems -Signal Processing -Semiconductor Design -Optoelectronics and Photonics -Control Systems -Robotics -Bioelectronics And I'm sure I'm missing a few. There's alot of cross-breeding between those fields though, so maybe it's best that EEs not be split up? Cuw is right though, there's no way anyone can master 'Electrical Engineering' as a whole in 4 or even 6 years.
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# ? Jan 13, 2008 23:40 |
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Another item you guys might be interested in is Proteus VSM: http://www.labcenter.co.uk Basically in addition to being able to do spice simulation like the other simulators, it can also simulate a microcontroller at the same time. So you can setup complete projects and simulate them software and all before putting iron to solder. Definitely not free though.
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# ? Jan 14, 2008 06:26 |
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# ? May 21, 2024 18:01 |
ValhallaSmith posted:I've built tons of those. What I'm trying to come up with is something very cheap for the hobbyist. The reason I would go with a pic or avr is because using one of those over USB is cheaper than adding in everything you need for a display, controls and switches. Plus I want to keep these at a very small form factor (altoid form factor). I've been reading up on synthetic instrumentation for a chunk of the day. I might draw something up that heads in that direction. Instead of a power supply you could basically build a DAC. Then if you want a voltage meter you add a ADC voltage module. If you want power factor correction/metering you add a shunt resistor, amp and another adc. Basically a very generic instrument set that performs most of the measurement on the PC. It would be USB 2.0 based so that would kind of limit things at times. USB has crappy latency. The next logical step up from a linear regulator would be a switcher, which is what I think most good bench supplies use. But unless you're very concerned with load and line regulation, it probably wouldn't be worth the added complexity over a linear supply.
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# ? Jan 14, 2008 18:17 |