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ante posted:Make your own x-ray machine That would be a pretty useful project actually, as long as it was made safely. This guy acquired an x-ray tube head http://www.youtube.com/watch?v=Qrni6AkEeV and made some neat photos. I don't think he was very safe about it though.
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Apr 20, 2010 04:52
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King Nothing posted:Yeah, basically think of something you want to sense (humidity, light, temperature, sound, whatever) and something you want to do in response. Potentiometers (pots) are useful, tri-color LEDs are fun. I usually keep stock of common things. I have a general kit of various axial components, resistors, caps some regulator ICs. Also supplies like FR4, wires, solder etc. Basically stuff that will work for any prototype. https://www.danscloseoutsandspecialdeals.com , allelectronics.com and https://www.goldmine-elec.com are cheap if you want to stock up on misc parts.
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Apr 23, 2010 07:37
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ANIME AKBAR posted:Okay, not precisely electronics, but we just finished off our devices for our MEMs class. Interesting, was this something built in house or was it sent off to MOSIS?
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May 2, 2010 08:47
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Looks like TI's site is unfucked again. 4.30+free shipping. Probably going to be a delay in getting one though. They seem to be a wee bit popular.
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Jun 23, 2010 06:01
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Corrupt Politician posted:Can anyone give me advice on connecting a surface mount chip without a PCB? I have this somewhat obscure op amp that only comes in a 20-PSOP package, and I want to connect it to a power supply I'm building, but all the surface mount soldering tutorials I find online involve soldering to a custom PCB with a designated slot for the chip. I just want to be able to connect this thing to a breadboard. Here's a picture of the chip: Two ways you can go about it. Flip the chip upside down and hot glue it to a piece of copper clad. Solder small wires to the pins. Then take a razor blade and cut some of the copper clad away so you have isolated pads for the wires to connect to. Otherwise if you can be precise plop the chip down, mark where copper should be missing between the pins and cut that away. Heating the area you want to remove works pretty well to delaminate the copper once you make the cuts. Really unless you absolutely have to use something else just buy a stack of FR4 off ebay for less than the price of a couple adapter boards. You can just cut and hack that to make almost anything you need. Throw those tired old bread boards and vector boards out.
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Jul 17, 2010 10:25
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Hurricane human being posted:Would something along the lines of baking soda work to neutralize it? Kind of worried about the sludge too because it really doesn't seem like it should be tossed directly into the garbage. Yes, Just be sure to add it slowly until the PH gets above 7. You can throw the sludge safely away, or save it till there is a local "hazardous" material collection. The copper ions are fairly poisonous in solution. But once they are insoluble salts its not so bad.
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Sep 9, 2010 12:07
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Unparagoned posted:It's a breadbord. I currently have a nice resistor burn mark on my finger. I've had it on ice for the last few hours. I just thought there might be a better way. I dunno, maybe hold your finger over it for a second without touching it to see if its blazingly hot. I think most people over 8 have figured this out. Otherwise many multimeters support thermocouples. Or get one of those IR temp sensors.
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Oct 18, 2010 23:37
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riichiee posted:- 12V Lab Power Supply. For spice I just use ltspace. Works good and has a decently sized community in case something goes wrong. People are going to suggest bitscope, picoscope, etc for oscilloscopes. Ignore them. Either troll craiglist/ebay for something useful or just buy a normal one. Rigol and the chinese makers have low end scopes at around the 300-400$ mark. That gets you 1 gig/sample which is probably 5X the sample rate of the headless scopes. For power you could just make something out of an old ATX power supply. As long as your projects can take a little noise. I don't see a soldering iron on there. But knock offs of Hakko products are fairly popular. Buy a box of FR4 off ebay or locally. Its fantastically useful stuff to have around. Also get a dremel or equivalent for hacking it up. I use a dremel and FR4 to make quick circuits. Works especially well for switching power circuits since solderless breadboards have big capacitance issues. As far as ICs and other stuff to get. Just keep an eye out for decent assortments of parts. The surplus sites like electronic goldmine or Dan's deals can have good deals sometimes.
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Nov 18, 2010 22:01
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Unparagoned posted:What's wrong with picoscope? The one he is probably looking at runs at only 200Ms/s. Thats good for around 20Mhz signals. In the future it will be a limiting factor as you continue with electronics. Just pony up the extra 100$ for a real scope. Low end rigols can be patched to 1G/s@100 Mhz. And Tekways are currently being hacked to 1G/s@200 Mhz. The tekway might actually be hackable to a higher sample rate as well eventually. Plus you don't need a PC to use it. 100$ difference.
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Nov 19, 2010 03:59
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Anyone know a good source for small super cheap displays? I'd like something 2-3" square. Monochrome, LCD or whatever technology is cheapest. Probably need 100 of them. Nothing fancy but places seem to want 10$ per part for even the bottom of the barrel. I'd be willing to use surplus stuff if I can get enough.
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Nov 23, 2010 05:19
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Thanks for the display suggestions guys. Might get one of them. Anyone else enter that Renesas design contest with the free devkit? Finally got mine in via fedex. With the almost 900 page hardcover book included I think it might actually be a better deal if they just gave you a wifi kindle with all their documents on it. ValhallaSmith fucked around with this message at 18:49 on Nov 29, 2010 |
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Nov 29, 2010 17:45
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Frobbe posted:y'know, if you had told us about it when there was still devkits available to get, i bet more people would've entered It was pretty widely advertised. There was a thing on most of the major "maker" sites, eevblog, etc.
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Dec 1, 2010 22:25
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crabrock posted:I'm currently trying to teach myself how to make circuits and solder and what not. I've done a few tutorials and kits from sparkfun, and feel like I have the super very basics down (but am still quite overwhelmed--this stuff is hard!). Assuming this means you want your circuit to be off if it isn't receiving enough voltage. You want a voltage regulator with a low voltage cutoff. Or use a switching chip to do it. crabrock posted:Problem 2: All capacitors leak charge. I believe TVs and such that have very high capacity capacitors have high value resistors across them to drain them off within 15 minutes. Thats probably changed with newer TVs. crabrock posted:Problem 2.5:
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Dec 5, 2010 03:10
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Krenzo posted:I'm trying to do time of flight stuff: send out a single pulse from a transmitter and time how long it takes to reach the receiver. I have several FPGAs and have built a test circuit that can time the travel time of a square pulse through a wire to within about 100 picoseconds (I'm planning to reduce the noise to get a more accurate timer). The next part is to construct a UWB transmitter and receiver to replace the wire that the pulse travels through. However, the difficult part I'm having to deal with is figuring out how I'm going to troubleshoot any problems I may encounter with such narrow pulses (ones that will register in the >3 ghz range). To even be able to see the pulse with an oscilloscope would take a very expensive one. I'm currently trying to ask electrical engineer grad students at my school to figure out if the university has any fast scopes I could get some time with. I hate the idea of getting into this project and not have any concrete feedback as to what's going on, ie if things are really operating how I planned them to. Why do you need UWB? Or do you plan on scanning through specific frequencies? One thing you might consider is just using dirt cheap DBS LNBs for your transmitter and receiver. It would be easier than building a UWB from scratch and have less need for a high speed RF scope. http://www.youtube.com/watch?v=vDyo_OQFdAc is Jeri Ellsworth's take on modifying a LNB.
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Dec 5, 2010 11:28
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crabrock posted:Thanks to whomever tried to help me, I made a little bit of progress but I'm still not really sure how to do what I want to do. I thought maybe some pictures would help. Is this just to do it or do you have an application in mind? This is basically a switched capacitor LED driver. There are versions that flash LEDs at various speeds as well.
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Dec 7, 2010 09:21
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Corla Plankun posted:I can build a communications circuit of some kind, OR I can simulate something in the design program of my choice. I was thinking about simulating some kind of interesting network topology/protocol like multiple-base wireless reception or something. If it were me, and well being me, I'd go for something like setting up a audio frequency link between two computers using GNU radio and the computers sound cards. Then I'd hook up a noise generator/frequency generator/arb and a competing gnu radio audio source. Then you can use this to demonstrate the effectiveness of various encodings and filters.
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Mar 30, 2011 13:48
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Weatherproof posted:Here's a bit of a weird one: Vero boards have much less capacitance than bread boards. Your circuit was stable on the breadboard because of that. Touching it is adding enough capacitance to keep it stable like on on the breadboard. http://users.ece.gatech.edu/~lanterma/sdiy/datasheets/opamp/audio_circuits_ne553x.pdf is an app note for audio circuits using that chip. You need to put a 22pf or so cap between pin 8 and 5 more than likely to keep it stable.
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Apr 22, 2011 09:24
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Weatherproof posted:Thanks so much, that makes sense! I'll give it a go tomorrow when I'm back in the lab and will report back. Yea, just a bog standard unpolarized ceramic is fine.
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Apr 22, 2011 10:17
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Krenzo posted:So who here is knowledgeable about high bandwidth scopes? I'm in need of a scope with at least 5 GHz of bandwidth. I looked at renting one, but it seems like buying an older one off of eBay may be better. I see Tektronix 11801C scopes (with sampling head included) going for slightly cheaper than what it would cost to rent a newer scope. What sort of signals are you trying to look at? There is a bit more to it than just bandwidth. What sample rate? What sort of triggering. Etc. For example, the scope you are looking at has an analog bandwidth of 50Ghz max. But it only has a sample rate of 400Khz. ValhallaSmith fucked around with this message at 12:22 on May 6, 2011 |
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May 6, 2011 12:19
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Krenzo posted:I see there are copper boards you can buy that have photosensitive coating already applied which you expose to get your design onto the board. Is there a way to coat a plain copper clad board with that material to avoid paying $20/board? Yep, a ton of products out there. Not all of them liquid. You can get a dry resist that laminates on as well. http://www.genesismt.com/products makes AQ 3000 which seems to be popular. Needs to be dip or spun. Otherwise you could get a spray can of positiv 20, but its really finicky. Or dry film. If you are not doing ultra tiny pitch parts dry film might work for you.
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Jul 6, 2011 07:42
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