Electrical Engineering V2 - Developers

[QUOTE=chipset;44414226]Shift registers are trivial. [b]This[/b] [img]http://i.stack.imgur.com/oUDHL.png[/img] is black magic.[/QUOTE] Make sense that microstrips would be used considering the high frequencies which would plague housed components (I assume parasitic inductance is kept at a minimum with microstrips). This is the work of some EM wizards. [editline]31st March 2014[/editline] On an unrelated note, Atmel is having an [URL="http://app.snapapp.com/simplyavrcontest"]AVR Competition[/URL] for $1500. Just in case anyone would like a nice bit of competition or potential project money.

I've often seen 2n2222 mentioned as a "must have" for your parts bin. After spending about an hour reading about them I still don't understand why I would want one. [editline]1st April 2014[/editline] I've never used a transistor before so that probably doesn't help.

[QUOTE=Leestons;44416486]I've often seen 2n2222 mentioned as a "must have" for your parts bin. After spending about an hour reading about them I still don't understand why I would want one. [editline]1st April 2014[/editline] I've never used a transistor before so that probably doesn't help.[/QUOTE] The 2N2222A is such a flexible general purpose BJT because of its relatively low parasitic capacitance for VHF, solid HFE, good bandwidth product, and strong sinking capabilities, needless to say a flexible go-to transistor that's dirt cheap.

You're not having fun until you're using transistors! Find some basic transistor circuits on google and buy a few of the more commonly used ones in those examples. I would think that should get you understanding the basics of how to use and [B]destroy[/B] them.

[QUOTE=LoneWolf_Recon;44415666]Make sense that microstrips would be used considering the high frequencies which would plague housed components (I assume parasitic inductance is kept at a minimum with microstrips). This is the work of some EM wizards. ...[/QUOTE] But I don't think those are micro strips. Those are passives done with PCB traces. Unless passives done with PCB traces are called micro strips.

[QUOTE=Zero-Point;44415182]I'm going to be completely honest: I have no fucking idea what those things are or what purpose they serve. [url=http://en.wikipedia.org/wiki/Distributed_element_filter]And after a quick Google reverse-image search[/url], I'm still "HADURR!".[/QUOTE] When you get into frequencies so high, that the wavelength is about or less the size of the components you're working on, you can't use those components anymore. They will have too high inductances and capacitances, not to mention the hard to calculate parasitics which really do matter at that point. So, instead of fiddling with components, why not just use the parasitic properties of little strips of conductors in a controlled fashion? That way you get really precise and low values of inductance and capacitance, and it can all be calculated rather easily. For example, where 2 strips meet, you have a capacitor that almost looks identical to the classic 2-plate capacitor. Where the strip becomes really thin, you have an inductor. For example, in the middle of the image where you have a thin strip with 2 cones (they're capacitors) coming form them, you have something similar to this circuit: [img]http://www.electronicproducts.com/images2/fundamentals_inductors_5_jul2011.gif[/img]

Coil of EMP jammer (actually, 1 coil and 1 antenna), un-tested [IMG]http://i.imgur.com/1iDdJ4S.jpg[/IMG]

[QUOTE=Zero-Point;44415182]I'm going to be completely honest: I have no fucking idea what those things are or what purpose they serve. [url=http://en.wikipedia.org/wiki/Distributed_element_filter]And after a quick Google reverse-image search[/url], I'm still "HADURR!".[/QUOTE] It gets even crazier when you look at them doing it on silicon chips in 3d: [img]http://moodle.insa-toulouse.fr/pluginfile.php/2665/mod_resource/content/0/content/images/inductor.jpg[/img] And they even make self assembling coils at that scale (Microassembly of 3D MEMS Microstructures) [t]http://www.mie.utoronto.ca/faculty/cleghorn/projects/Microassembly/Microassembly-Examples/6-Loop-MicroCoil-Pic1.jpg[/t]

As my birthday arrive, I want to start fiddling with electronics. What do I need, what should I buy to start ?

[QUOTE=neroe23;44421011]As my birthday arrive, I want to start fiddling with electronics. What do I need, what should I buy to start ?[/QUOTE] start with a resonable power supply and a cheap oscilliscope. Oscilliscopes are good as they not only show voltage over time, but they work as reasonably good voltage meters, allowing you to see low voltages without another peice of £££ equipment at fairly reasonable accuracy. Also look out for surplus electronics on ebay. Try finding large boxes of components. ooor buy old equipment and salvage for more expensive parts (im looking out for channel mixers and amplifiers for heatsinks, power components and loads of potentiometers.

I home-brewed a breakout PCB for the 3 x 3 mm 20 QFN chips I'v got. Then I sat for an hour and thought to my self: Holy shit, I made a PCB at home with traces as wide as 2 strands of hair. Then came the time for soldering the chips onto the boards and I fucked everything up. First I tinned the PCB pads, then the pads of the chip, applied plenty of flux on the board, aligned the chip as well as I could and nothing happened. The chip just wouldn't realign. Sometimes it would just float away on the bubbles of the heated flux. Should I try ordering boards with soldermask or just forget trying to solder those tiny shits?

[QUOTE=alexaz;44421431]I home-brewed a breakout PCB for the 3 x 3 mm 20 QFN chips I'v got. Then I sat for an hour and thought to my self: Holy shit, I made a PCB at home with traces as wide as 2 strands of hair. Then came the time for soldering the chips onto the boards and I fucked everything up. First I tinned the PCB pads, then the pads of the chip, applied plenty of flux on the board, aligned the chip as well as I could and nothing happened. The chip just wouldn't realign. Sometimes it would just float away on the bubbles of the heated flux. Should I try ordering boards with soldermask or just forget trying to solder those tiny shits?[/QUOTE] Put a little blu-tac below the chip so it doesn't move.

[QUOTE=Chryseus;44421666]Put a little blu-tac below the chip so it doesn't move.[/QUOTE] But then how do I align it to the pins? The traces are 0.2 mm wide.

[QUOTE=nuttyboffin;44421063]Oscilliscopes are good as they not only show voltage over time, but they work as reasonably good voltage meters, allowing you to see low voltages without another peice of £££ equipment at fairly reasonable accuracy.[/QUOTE] could you recommend a cheap one? its more or less the only thing missing in my "starter pack"

[QUOTE=hanfer;44421748]could you recommend a cheap one? its more or less the only thing missing in my "starter pack"[/QUOTE] Since you are in Germany, I suggest you take a look around the German ebay. Look for a second hand analog if you want to go cheap.

[QUOTE=hanfer;44421748]could you recommend a cheap one? its more or less the only thing missing in my "starter pack"[/QUOTE] Define your max budget. [editline]1st April 2014[/editline] [QUOTE=alexaz;44421699]But then how do I align it to the pins? The traces are 0.2 mm wide.[/QUOTE] Carefully, very, very carefully.

[QUOTE=nuttyboffin;44422205]... Carefully, very, very carefully.[/QUOTE] Heh, even the slightest nudge sends the chip flying across the universe.

[QUOTE=hanfer;44421748]could you recommend a cheap one? its more or less the only thing missing in my "starter pack"[/QUOTE] An old analog is the cheapest quality scope your going to find. 10MHz bandwidth with two channels is enough for a beginner, 20MHz recommend.

[QUOTE=Chryseus;44422344]An old analog is the cheapest quality scope your going to find. 10MHz bandwidth with two channels is enough for a beginner, 20MHz recommend.[/QUOTE] I dissagree. You want to try get a second hand 50-100Mhz one, i managed to get 2 for £50 each. If you have the money, get a digital one, i know i will when i have the money.

[QUOTE=alexaz;44421431]I home-brewed a breakout PCB for the 3 x 3 mm 20 QFN chips I'v got. Then I sat for an hour and thought to my self: Holy shit, I made a PCB at home with traces as wide as 2 strands of hair. Then came the time for soldering the chips onto the boards and I fucked everything up. First I tinned the PCB pads, then the pads of the chip, applied plenty of flux on the board, aligned the chip as well as I could and nothing happened. The chip just wouldn't realign. Sometimes it would just float away on the bubbles of the heated flux. Should I try ordering boards with soldermask or just forget trying to solder those tiny shits?[/QUOTE] Most PCB manufacturers can't print soldermask inbetween QFN pads anyway, so there's that. The biggest mistake you can make with QFN is to apply too much solder. It will result in the device floating on the bubble of solder in the middle, so the pins can't make contacts. Soldering QFN at home is possible, and I've done it before, although it's way nicer and more reliable if you have a stencil.

[QUOTE=Chryseus;44422344]An old analog is the cheapest quality scope your going to find. 10MHz bandwidth with two channels is enough for a beginner, 20MHz recommend.[/QUOTE] Depends, I'd get at least 100Mhz, it comes handy if he will be doing microcontroller stuff or coils stuff I have 20Mhz analog oscilloscope and let me tell you, you will clearly see frequencies only at 4Mhz or so, because of sampling rate.

[QUOTE=nuttyboffin;44422205]Define your max budget.[/QUOTE] absolute max 100€ (~140usd)...but the less the better.

[QUOTE=hanfer;44430034]absolute max 100€ (~140usd)...but the less the better.[/QUOTE] Loads of second hand scopes on ebay. try to get one with an image of it working, or at the least a buy it now with a listing of scopes and no complaints but at least 5 sales.

These things are so useless but cute [t]http://i.imgur.com/hKlYVSA.png[/t] why did I buy two of these :v:

[QUOTE=scratch (nl);44439975]These things are so useless but cute [t]http://i.imgur.com/hKlYVSA.png[/t] why did I buy two of these :v:[/QUOTE] They'd make nice adapters for modules with dual-row headers

Does it even have traces or is it just a protoboard?

[QUOTE=Tw34k;44441627]Does it even have traces or is it just a protoboard?[/QUOTE] There's some small traces for power, but most of this is protoboard (Its included with Digisparks/stumps, which you can get from [URL="http://digistump.com/distributors"]their site and distributors[/URL])

Speaking of protoboard Do any of you gents have a good source on some decent pad quality perf/proto/strip boards that are moderately priced? I'm sorta getting tired of these ebay boards with what I'm assuming are glued on pads with how easily they flake off. Aww yeah, this hotness right here... [IMG]http://i.ebayimg.com/00/s/NDQ2WDU5Ng==/z/GR4AAMXQhpdRyG0u/$(KGrHqJ,!ogFHFg2YquBBRyG0tC96g~~60_12.JPG[/IMG] [url]http://www.ebay.com/itm/140765639135?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649[/url]

Finished soldering and wiring my Mr General robot! Although I think I need to take a look at the code instead of randomly uploading samples. [media]http://www.youtube.com/watch?v=arlKJsmM_e8[/media]

That's awesome, how much did it cost?