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Horowitz and Hill got me through Intro to Electronics last year, even though it's 16 years out of date. The current de facto standard text (Sedra and Smith) just isn't nearly as good.
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Jan 15, 2008 16:10
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scholzie posted:God, I need an oscilloscope. I found one on ebay being sold as-is. It powered on but didn't have a probe so it couldn't be tested. But, it was a newish HP 4-channel scope, and it was $10. I was top bidder until FOUR SECONDS before the end of the auction when someone bid-sniped me. I hope that fucker just bought a broken oscilloscope. My Uncle goes around to government and school surplus auctions buying lots of old electronics, mostly consisting of old scopes and bench power supplies. He fixes up what he can, and sells the rest on ebay. Sometimes, he'll buy a crappy lot, but overall he's well ahead of the game. If you've got some time and skill with a soldering iron, it might be the way to go. It's a pretty sure bet that you'll find something decent under 100MHz. For anything else, you're better just hitting up ebay directly.
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Jan 17, 2008 15:31
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scholzie posted:This sounds like a good idea. The only problem I can find is that I probably wouldn't know what was broken on the scope if it didn't work. I'm handy enough with a soldering iron to fix it once I knew, but... yeah. Mostly he just replaces obviously broken components-- Busted Caps, broken CRTs, and so on. When you buy a pallet full of nearly identical scopes, you'll get enough spare parts to get at least a few working ones.
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Jan 17, 2008 17:57
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Phlegmbot posted:If I were actually trying to learn electronics from this thread, I'd be so drat confused. To be fair, a lot of other hobbyist sites and books and magazines aren't a lot better. I didn't start to truly understand any of the more complicated stuff (Transistors, etc.) until I started studying it in College.
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Jan 21, 2008 17:12
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Poonpalace posted:I'm taking "advanced lab" for physics and we are using The Art of Electronics by Paul Horowitz. Does anyone have any experience with this book? I have only taken some simple circuit design in a normal university physics class and I am a little worried because the book looks quite complex. This is actually the best textbook there is for electronics. It might look complicated, but reading through it, and with some additional "push" from your Lab TA or Teacher, you shouldn't have a problem at all.
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Jan 22, 2008 04:09
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Phlegmbot posted:You get the idea. Basically follow the curriculum of any first-year circuits course. My first-year circuits course included a moderate amount of physical electronics, and I think I'm a little better off for it. Although we didn't have to know anything terrifically in depth, just having some of the stuff worked out on the board helped a lot in conceptualizing a lot of stuff. One cool thing our teacher did was to bring in a giant inductor, and hook it in to a simple RL circuit with a cutoff in the middle. To illustrate that you couldn't change the current across an Inductor instantly, he threw the cutoff, and you could watch it arc across the several inch gap created. It was cool stuff.
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Jan 22, 2008 06:00
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SuicidalSmurf posted:Looking at the specs for this chip on digikey, it appears the supply voltage is between 4.75-5.25v. This will be switching 12vdc. Is there a similar chip with higher voltage capabilities or am I missing something? You don't want to be using logic chips to directly drive anything. They can only source so many mA of current, and sink only a little bit more (refer to your data sheets for the exact numbers). Connect to the rest of your device through a transistor or relay.
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Feb 8, 2008 00:13
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Cuw posted:I got my Jameco grab bags the other day and drat were the parts crappy. I recommend the Electrolytic grab bag without question but the TTL one was basically 40 line buffers and a few CMOS NAND gates. Nothing really worth it at all. The Analog IC bag was just a ton of poo poo that is basically useless. I'm not so sure I can recommend the grab bag for resistors. I didn't get a single resistor between 43 ohms and 2.2K ohms, and the vast majority (over 1/3rd) were 3.3K Ohm resistors. I didn't order the grab bag to get a bag full of the same resistor!
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Feb 26, 2008 03:45
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SporkOfTruth posted:As another example, some Mech. Eng. friends of mine had it as their textbook for their "Advanced Electronics" class, but they ended up using Google and another textbook (Sedra and Smith's Microelectronics, for the record) more often. Mind you, these people were not new to basic circuit analysis or design. They took the same first circuits class that I had to take and did reasonably well! The lack of depth I was talking about earlier actually made it harder for them to understand the concepts behind stuff like Schmitt triggers and various rectifiers, because it basically said "This is a blah, look at this graph to see what it does, here's some historical background." Couple that with a terrible professor (or trying to self-teach), and you're not helping yourself. I had a similar problem: My Electronics professor was absolutely terrible. The class text was Sedra and Smith, and paired with his poor instruction, it made absolutely no sense. I ended up supplementing with The Art of Electronics and Google, and ended up the better for it. I'm not sure if there's a single really good text for self-teaching out there, though.
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Apr 18, 2008 12:48
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Nubile Cactus posted:What's a good way to get into microprocessors? I'd like to get one of the cheaper Atmega chips to learn with, but I'm not quite sure what'd be the best introductory/cheapest way to learn how to program the chip. I've seen some programmers such as the STK500 (something around that I think) but I don't really want to spend $50 or $100 on this quite yet. If you don't want to work with a more all-in-one solution, the guides over at Sparkfun are great: http://www.sparkfun.com/commerce/hdr.php?p=tutorials Instead of getting the sparkfun programmer, I bought the USBtinyISP from Adafruit industries: http://www.ladyada.net/make/usbtinyisp/index.html
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Apr 20, 2008 06:03
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I have a question regarding servo motors. I recently discovered this website: http://leavemealonebox.com Essentially, it's a box with a single switch on it. When the switch is flipped, a hand comes out of the box, and turns the switch off, then disappears back into the box. He uses two servo motors controlled by a microcontroller to open the lid, and flip the switch back. The way the hardware is designed, it appears that the servos will move into a set position when a port line is placed at Logic 1, and return to their original positions when the port line is returned to Logic 0. I know quite a bit about Microcontrollers, but absolutely nothing about interfacing with motors or servos. How would I construct a device like that? Actually, is there a site out there for beginning robotics for people that aren't completely new to electronics? I'm a 3rd year EE student, so I've got a more than basic grasp of electronics, I just don't know anything about robotics.
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Apr 25, 2008 01:07
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I'm having some trouble figuring out how to interface a handful of 14-segment displays to a microcontroller. The micro I'm using has enough power to drive the LEDs directly, but there's no way I can sink the necessary amount of current through the micro to properly multiplex the display. Allegro made a current sinking driver chip at one time, but it has since been discontinued, and Maxim makes a chip that does a fantastic job of controlling the displays directly, but it's $15 a pop, and moreover hard to find. What are my options here?
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Apr 28, 2008 13:54
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Cuw posted:you can use a BJT or MOSFET low switch to dump the current. A very cheap 2n3904, i think they are $.02 a piece, can deal with 100mA current sustained and 200mA peak and still operate pretty well at 25MHz, although you aren't going to be switching anywhere near that speed. I can drive the segments fine from the Micro (or, in this case, a shift register to minimize port lines), but each segment is common cathode, so I could (theoretically) need to sink up to 300mA of current.
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Apr 28, 2008 21:32
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babyeatingpsychopath posted:I did a search on digikey for LED Driver, 16-channel, 100mA per channel, and found a couple of decent candidates looking like "IC LED SINK DRVR 16BIT". The data sheet shows a serial data in/out, output enable, failure sensing, thermal shutdown, and 16 outputs in a 24-pin package. $2.94 each. That's almost exactly what I'm looking for, but I need it to sink at least twice as much current. I think this will work: http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=260144
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Apr 28, 2008 22:50
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Cuw posted:well there are higher current BJTs, they go up to about 1A, for cheap so current shouldn't be an issue. The real issue will be wiring everything. Yeah, that's the trouble I'm trying to keep to a minimum. What I'd really like is a current replacement for the Discontinued Allegro UDN2595A, which does exactly what I need to have done.
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Apr 29, 2008 18:40
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Well, after several hours of re-teaching myself C, I finally have a working program to interface with an 8-bit parallel LCD display for an AVR ATMega 168. I bought a parallel display because they're $10 or more cheaper than serial displays, and I have a pile of shift registers laying around. I also got my sample order in from Maxim. For being a student, they sent me a couple segmented-display interface chips that retail $15 a piece for free, and according to the brochure they sent me, they'd be willing to send me 14 more. Maxim rocks.
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May 3, 2008 22:55
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Hey guys, I'd like to design an automatic drip-irrigation system for my garden. Unfortunately, I can't find any cheap source for small flow-meters or valves. Do such things exist? The sort of pressures and flows I'll be dealing with are seriously negligible, and accuracy isn't a big deal. Anyone have any ideas?
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May 27, 2008 20:17
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I've ordered there before. The shipping was a little slow because I got the cheapest shipping option, and she's pretty far away, but otherwise fantastic.
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Jan 10, 2009 21:02
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Paul MaudDib posted:I got a usbtinyISP from her before Chriastmas, it came in <1 week and I soldered it up. It's a great deal if you want a programmer. I'm kinda wishing I went for futurelec's programmer because it has JTAG, though. The futurlec programmer is just an avr ice clone, which can only do JTAG programming/debugging on a limited range of chips (Granted, this includes the popular 16x series). You can build it out of parts for less than $15, and buy a kit for under $20. I think I'm going to end up buying the AVR Dragon. I'd like to have JTAG debugging for the atmega 324P that I'm using for an upcoming project: Designing a "smart" power outlet that monitors power usage, and can shut off an outlet based on time/date settings, or power draw. This will all interface to a PC wirelessly.
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Jan 15, 2009 16:47
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PDP-1 posted:Does anyone know a good way to adapt a surface-mount chip to a DIP format? I found a programmable function generator (AD9833) that would be perfect for my current project, but it is a surface mount chip which makes it hard to breadboard. You could dead-bug the chip:  (Not mine, from: http://macetech.com/blog/node/23) Or buy something like this from SparkFun: http://www.sparkfun.com/commerce/product_info.php?products_id=494
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Jan 25, 2009 05:00
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I'm looking for an ultra-low cost wireless transceiver. I don't care about bit rate or range (as long as it's over 4 feet), just power consumption and cost. All I need to transmit is a simple on/off signal, and the closest I've come have been these guys from sparkfun: http://www.sparkfun.com/commerce/product_info.php?products_id=8948 But the transmitter and receiver are separate devices, and together they're both larger and more expensive than the rest of my project. Any ideas?
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Feb 16, 2009 21:47
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Cross_ posted:Since you mentioned FPGAs, I almost picked up one of these boards last year: I got this guy for Christmas: http://www.digilentinc.com/Products/Detail.cfm?Prod=BASYS&NavTop=2&NavSub=457&DetailType= I wish I had gotten the Nexsys, though, for all the extra IO. I'm having trouble thinking of neat projects, though.
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Feb 27, 2009 04:24
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ANIME AKBAR posted:Yeah I totally agree. My school offers a course in practical use of FPGAs where you use a dev board and learn to use VGA, rs232, keyboard and mouse interface, and eventually build a working calculator (most of the work is getting the VGA and keyboard working, from what I've heard). I'll certainly take it next semester. From what I know, you can use Verilog, VHDL, and also some neat state machine generators. Our VHDL class used a Xilinx 500k Gate chip, and culminated in... A device that would act as a 3 digit counter and 4 bit multiplier, output to 7 segment displays, with a mode switch between the two. Some of the abysmal failures of the course managed to take up 25k gates with that bad boy, though.
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Feb 27, 2009 21:44
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Nerobro posted:well there I go. Soldering again. I've been bickering with a rep from Seeed on another forum for a while now. He's somehow convinced that their rates for PCB fabrication are lower than Gold Phoenix's, which is flat out wrong. They sell some interesting products, but it seems like all the Chinese companies out there refuse to accept that they might not offer precisely what you need. I will probably end up buying that o-scope kit, though. I tried my hand at surface mount soldering for the first time the other day:   I bought this kit: http://practicalcomponents.com/boards/solder-practice-pc003.htm which comes with dummy components to populate the board. The kit was about $15. If anyone is interested, I'd be willing to buy a bunch and resell them, since Practical Components isn't really set up to take individual orders very well (especially not over the internet.)
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Mar 6, 2009 02:02
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clredwolf posted:Very nice job. I see a few little blobs here and there, but nothing too messy. On that PLCC on the bottom, I think having more heat and/or using a slightly bigger iron tip may help. The PLCC was the most retarded thing to solder. Looking at it under magnification, all the connections are electrically fine, and there are no solder bridges, but it's ugly. The rest was easy-peasy, though. I'll be soldering everything I can surface mount from now on.
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Mar 6, 2009 05:09
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Snaily posted:I would, if I could find a comparable devkit compatible with a low-power chip. As a hobbyist, price tag does mean quite a lot, unfortunately. Digilent has what you need: http://digilentinc.com/Products/Catalog.cfm?NavTop=2&NavSub=400&Cat=Programmable%20Logic Their Dev boards have a lot of "extra" stuff that draw power in addition to what you'd be using, but if you were actually implementing a design, you wouldn't have to include that. Even at full tilt, they don't draw a boatload of power. The C-Mod might be what you're looking for (or a similar product), although I don't know if it has the capacity for what you'd like to do. The Data sheet for the XC2C64 says it draws less than 100uA at all times.
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Mar 10, 2009 17:27
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hobbesmaster posted:My school takes care of that issue by having the worst teacher in the department always teach the required undergrad EM class. Hey, my department too. Moreover, the signals and systems course (Fourier transforms, Review of Laplace transforms, and pretty much every other precursor to DSP) is taught by a rotating cadre of visiting professors. The one I had got a grand total of 4 weeks into a 16 week syllabus by the time the semester ran out. Everything I know about Fourier transforms I was self taught, which pretty well kills my confidence for trying to take any DSP classes.
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Mar 18, 2009 18:11
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Hey guys, I know this is a long show, but I'm desperate: I'm having trouble discovering the Sparkfun's WRL-08469 Bluetooth-UART bridge device. (http://www.sparkfun.com/commerce/product_info.php?products_id=8469, based on the NXP BGB203). When I am able to discover it, the link is good, and the device works as expected. Unfortunately, this only happens sporadically, and I am at a loss to figure out why. I've got the WRL-08461 interfacing with an Atmega 324P. The module is the only thing on our board running at 3.3 volts, so we're running the TX(from uC)/RX(to Module) through a voltage divider, which appears to be working fine. The supply is very clean (less than 3mV ripple). We have the TX and RX lines connected appropriately to the Bluetooth adapter, as well as power and ground. PIO5 goes to an LED through a 330 ohm resistor into 3.3V. Reset is pulled high, and run through a debounced push button. No other pins are connected. We're trying to discover the device using 3 different bluetooth adapters on 3 different computers. When we ARE able to discover the device, all bluetooth adapters are able to discover the device, so the problem is definitely device-side. When we run "AT+BTINQ" on the device, we are able to see all the devices in the area, and AT+BTSDP works as expected for these devices. Entering data mode using "AT+BTSRV=1" does not result in the device being discoverable. "AT+BTSRV=1,"Serial Port", 000000000000, 0" does not result in discoverabilit. Using AT+BTCLT to connect from the adapter to a PC doesn't work either. The only thing that appears to work is pressing reset over and over until the device is discovered. At that point, the link is solid and reliable, and behaves as expected. I'm at a complete loss. Any advice is appreciated.
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Mar 28, 2009 02:55
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SnoPuppy posted:While I have never used this device, from reading the datasheet it sounds like it will enter the data mode whenever there is an active link. I would guess that it tries to set up a link on reset before it kicks over to command mode (hence why it works sometimes). The device enters data mode on reset, and the only thing that drags it back into command mode at that point is the escape sequence ("+++"). This works fine. Our wired communications with the device are rock-solid. The discovery problem persists even if we explicitly tell the device which server mode to enter (AT+BTSRV=1, "Serial Port", 000000000000, 0), which sets the device to become discoverable on RFCOMM port 1, advertising it's service as "Serial Port," and not give a drat about the host that attempts connection. We've been poring over ever single configuration option, restoring the settings to Sparkfun-default even. 4 days ago, wireless discovery and pairing worked flawlessly, and today, with the same hardware, same software and same settings, it doesn't.
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Mar 28, 2009 14:13
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Anyone have any advice for starting ARM development? Futurlec has some sweet ARM boards for next to nothing, and it's something I'd like to learn. (http://futurlec.com/ARM2103_Controller.shtml)
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Apr 10, 2009 01:48
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catbread.jpg posted:Not sure about the availability of a good toolchain for that. The documentation left me unclear as to how it's programmed. It seems like UART0 is used for ISP programming. Hold one of the GPIO pins low during Reset and the bootloader accepts programming through some method of encoding. The software that comes with it handles all that stuff. It's the toolchain stuff that's got me confused. What dev environments are reasonably up to date? I know IAR has a "kickstart" version which will program up to 32k for free (which would be fine for this particular uC). I tried installing Yagarto, but I got all sorts of quizzical errors (Probably relating to the fact that I'm running the windows 7 beta) when I tried to compile the sanity test dummy .c file. The latest stable version of WinARM appears to be 2 years old, unless I'm blind.
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Apr 10, 2009 14:23
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thepartypooper posted:I know I could just bit-bang it, or use another IO for the SS (which raises other issues as far as synchronizing it with the TX frame), but I figured maybe I'm overlooking something. Anyone have any experience using SPI with this part? I'm not experienced with the PICs at all, but most SPI devices I've encountered aren't really sensitive to timing delays between the SS and other lines, so you could probably use another IO for SS without any issues.
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Jun 19, 2009 11:57
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async1ronous posted:I have had a lot of luck with the inexpensive stations from https://www.circuitspecialists.com I happen to live down the street from them, but ordered one shipped to Texas as a Christmas present for my brother-in-law. He likes it as well. I bought a station from circuit specialists the same time a buddy bought the similar Hakko unit. There is no discernible difference between the two by any metric which matters. We aren't exactly soldering all day long, so I can't speak of long term durability, but I'm more than happy with my $35 saved.
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Jun 23, 2009 12:05
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Keebler posted:Alright, I think I may have made a rookie mistake here... Yeah, you'll need to hook the chip up to an external crystal to reprogram it. That, or use a high-voltage programmer to reset the fuses.
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Jun 23, 2009 13:49
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Mill Town posted:Also, to go with this, I'm looking for some thin, bright, cheap SMT LEDs. So far this is the best deal I've found, but it's a bit thick. Is there anything comparable that's a bit thinner? Honestly, the best source I've found for cheap LEDs is ebay. They'll take a little longer to ship, and the product description isn't very nice, but they are absolutely dirt cheap. I mostly buy through-hole LEDs, though, so your mileage may vary.
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Aug 7, 2009 13:25
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BattleMaster posted:Does anyone know of something like this that isn't such a ridiculous price? The important features are that it is in a DIP (SIP is cool too) package, runs at 3.3 volts and has a UART interface. I did a project using a module like this last year. The long and short of it is: No, there's no way to get a quality bluetooth module that interfaces via UART without shelling out some bucks. Even if you price out the discrete components, you're not saving a *lot* of money. The exception: Sometimes Chinese knock-off modules like this show up on ebay. I can't attest to their quality; We eventually broke down and purchased the sparkfun module. Another thing to note: These things are really particular about their power supply. The recommended power the datasheet mentions isn't just a recommendation-- any ripple over spec, no matter how tiny, and you'll start losing connections and other odd behavior.
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Aug 28, 2009 12:20
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I have a new project: I'm going to design a machine which can fill a case of beer bottles with homebrew. I figure I can scrounge parts from a printer or scanner to move the hose/nozzle assembly from bottle to bottle, and I'm going to use a solenoid and a pinch valve to shut off flow from the input bucket, but I'm having trouble figuring out how to stay on target with the bottles themselves. Measuring from the cases of bottles I have laying around, they're just imprecise enough that without some sort of intelligent bottle targeting, I'm just going to get beer everywhere. I'd like to avoid the mechanical complexity of a Z-axis moving the booze-extruder up and down (if I could do this, a simple mechanical funnel would do), but I can't think of any remote way of doing this that doesn't sound ridiculous. A small, cheap CMOS camera would be able to take a picture of the bottle, and a simple edge-detection algorithm would probably get me close enough to the center of the opening. Some intelligently placed IR sensors might accomplish the task, but if they're level with the beer bottles, I'm not sure how to guarantee that I don't bang the assembly into bottles. I need help brainstorming this one out.
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Nov 16, 2009 23:50
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ante posted:Could you make four intersecting bars close in on the neck of the bottle, locking it in place? That should probably centre it well enough to drop a funnel into it. I could, but I'd rather avoid the added complexity of something dropping town into the bottle. I don't have the skill or tools to create anything mechanically complex, but I am moderately confident enough in my ability to create something more complex logically.
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Nov 17, 2009 05:23
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Hillridge posted:Is the lack of precision due to the bottles themselves, or the case holding them? If the latter, just make a filling rig that locks them in uniform positions, or make it work more like a factory where the bottles are fed in one by one and you have to manually place them in the case afterward. Due to the case itself. I like the idea of a filling rig. I'd like to avoid the factory line feeling, since the point is to, at the very least, fully automate the most tedious part.
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Nov 17, 2009 14:36
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jailbait#3 posted:You do realize that you'll have a foamy mess if you don't have SOME sort of z-axis travel to insert a tube or filling wand, right? Just pouring the beer from a spigot will oxidize it and make a mess, especially if it's already force-carbonated. Definitely won't be filling the bottles with already carbed beer. Foam is going to be a concern, but I hope to be able to modulate flow rate so this isn't a problem. Also, after years of homebrewing, I'm not at all convinced that casual oxidation has any tremendous effect on a batch, of all the things that can't be controlled for in a homebrew situation, and even less convinced that the small drop into a 12 oz bottle is going to have any effect at all, let alone something readily detectable. I'm receptive to objective evidence to the contrary, but I've never read or experienced anything convincing. I really like the removable frame idea.
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Nov 17, 2009 17:45
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